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Home My WebLink AboutMiscAltmann Oliver Associates, LLC I'< l I~"' .", /,"-( ,lT 11,11 i, 111 \I \ '},'-.\( 11 I January 21. 2016 Rocale Timmons City of Renton 1055 South Grady Way Renton, WA 98057 Via email REFERENCE: Whitman Court FPUD -LUA14-000295 SUBJECT: Baseline Monitoring Report & As-built Plan Dear Rocale: AOA F nYi n ,nm l' n t,il Planning & l .and.scap<' .\re hi tl'ct ure AOA-4540 This report documents the baseline conditions for the approved Whitman Court Final Buffer Enhancement Plan dated 9-26-14 following plan implementation. The attached As- built Buffer Enhancement Plan dated 1-21-16 depicts as-built conditions along with the location of vegetation sampling transects and photo-points to be used during the 5-year monitoring period. 1.0 PROJECT SUMMARY The project is a planned urban development consisting of a commercial site to the north and 39 residential units. Scope of this plan includes portions within Tract A including the trail, fence and plant installation as depicted on the approved plan set referenced above. Existing previously planted buffer enhancement outside of the planting locations are part of the previously approved NGPA for the Ribera Balko Short Plat recorded on 4/9/2009. However, those areas will be monitored along with the new buffer enhancement plantings as part of the conditions of approval of the project. 2.0 PLAN MODIFICATIONS The buffer enhancement plan was implemented over the last few month. essentially per plan. We reviewed the project numerous time during and after implementation. Following were the few changes made during construction: 1. The buffer enhancement area was expanded by 1211 sf on the north end due to the extent of invasive removal resulting in the addition of 8 trees and 25 shrubs in this area. Rocale Timmons January 21. 2016 Page 2 of 7 2. The previous buffer enhancement (discussed in Section 1.0 above) was expanded by 1128 sf due to a larger extent of previous planting then previously realized. 3. Some additional plants were installed in the previous buffer enhancement area to the west and south of the detention pond totaling 75 shrubs. 4. The entire planting area was mulched continuously rather than in rings and seeded as we've recently found this course of action to result in higher recruitment of native species and less competition with grass and herbaceous plants, while still providing excellent erosion protection of the underlying soils. 5. A short block wall was installed at the base of the interpretive lookout area, adjacent the surrounding split-rail fence to stabilize the lookout and to provide clearer views into the wetland and stream. 3.0 VEGETATION SAMPLING TRANSECT DATA Three permanent 100' long by 10' wide vegetation sampling transects were established during our 10/23/15 baseline monitoring assessment. During monitoring events woody vegetation coverage and species diversity will be evaluated through use of the point- intercept sampling methodology within each of these sampling locations. Survival will be measured by counting live plants in the fall of each year and deducting them from the total installed. Herbaceous cover will be visually estimated. Following is the transect data and plant species composition from the baseline assessment. 3 1 TRANSECT DATA Transect fl %Woody % Herbaceous % Survival % Noxious Weed Cover Cover Cover 1 13.92 0.00 100.0 trace 2 14.25 0.00 100.0 0.00 3 6.92 0.00 100.0 0.00 Averal!e 11.69 0.00 100.0 0.00 Required at NA NA 100.0 0.00 baseline 3.2 SURVIVAL DATA 3.2A Transect 1 Transect one contained the following woody plants at baseline for a total of 3 trees and 12 shrubs: 1 big-leaf maple (Acer macrophyllum) 1 Sitka spruce (Picea sitchensis) 1 western red cedar (Thuja plicata) 4 salal (C,aultheria sha/lon) 1 black twinberry (Lonicera involucrata) 1 Pacific ninebark (Physocarpus capitatus) 3 rose (Rosa sp.) 1 snowberry (Symphoricarpos a/bus) 2 evergreen huckleberry (Vaccinium ovatum) Rocale Timmons January 21, 2016 Page 3 of 7 3.28 Transect 2 Transect two contained the following woody plants at baseline for a total of 6 trees and 9 shrubs: 2 vine maple (Acer circinatum) 1 big-leaf maple (Acer macrophy/lum) 1 western hazelnut (Cory/us cornuta) 2 Douglas fir (Pseudotsuga menzeisii) 1 western red cedar (Thuja plicata) 3 tall Oregon-grape (Mahonia aquifolium) 6 evergreen huckleberry (Vaccinium ovatum) 3.2C Transect 3 Transect three contained the following woody plants at baseline for a total of 3 tree and 7 shrubs: 1 western hazelnut (Cory/us cornuta) 1 Douglas fir (Pseudotsuga menzeisii) 1 western red cedar (Thuja plicata) 1 Pacific ninebark (Physocarpus capitatus) 1 salal (Caultheria shallon) 2 red currant (Ribes sanguineum) 3 rose (Rosa sp.} 4.0 PERFORMANCE STANDARDS The monitoring and maintenance program will be conducted for a period of five years, with quarterly reports submitted to the City of Renton for the first year after construction acceptance and annual reports submitted for Years 2-5. The primary goal of the mitigation plan is to increase the buffer functions over current conditions. To meet this goal, the following objectives and performance standards have been incorporated into the design of the plan: 4.1 Objective A Increase the structural and plant species diversity within the mitigation area. 4. lA Performance Standard for Obiective A Following every monitoring event for a period of at least five years. the mitigation area will contain at least 8 native plant species. Following each monitoring event, there will be at least an 80% survival rate of all initially planted tree and shrub species or equivalent replacement of a combination of planted and re-colonized native species. 4.18 Status of Performance Standard A at Baseline At baseline, 25 native plant species were present at the site with 100% survival rates. 4.2 Objective B Limit the amount of invasive and exotic species within the mitigation area. • Rocale Timmons January 21. 2016 Page 4 of 7 4.2A Performance Standard for Objective B After construction and following every monitoring event for a period of at least five years. exotic and invasive plant species will be maintained at levels below 15% total cover in all planted areas. These species include. but are not limited to. Scot's broom. Himalayan and evergreen blackberry. reed canarygrass, morning glory. Japanese knotweed. English ivy. thistle, and creeping nightshade. 4.28 Status of Performance Standard B at Baseline At baseline. invasive plants were well below the threshold. 5.0 PHOTOS FROM ESTABLISHED PHOTO-POINT LOCATIONS During the baseline monitori ng event six photo-points were established that will be monitored throughout the five-year performance monitoring period. The photos. whose locations are depicted on the attached as-built p lan. will be taken throughout the monitoring period to document the general appearance and progress in plant community establishment. Review of the photos over time will provide a semi-quantitative representation of success of the planting plan. Following are the photos taken during the baseline review. Photo-point 1. View loo king south Photo-point 2. View looking SW Rocale Timmons Janu ary 21. 2016 Page 5 of 7 Photo-point 3. View looking west Photo-point 4. View looking west Photo-point 5. View looking east Photo-point 5. View looking west Roca le Timmons January 21, 2016 Page 6 of 7 Photo-point 6. View lookin g south 6.0 MAINTENANCE RECOMMENDATIONS The following items need to be completed during the ongoing maintenance visits in March. May. July and October of each year to ens ure continued success of the mitigation areas. 1. Remove all invasive/non-native vegetation through hand-grubbing. Cut back encroaching blackberry along non-enhanced areas adjacent to th e mitigation planting area. 2. Remove any garbage and other non-organic debris from the site. 3. Install and act ivate irrigatio n system by April 1 per approved irrigation plans. Set fl ow to run V2" twice weekly June 15 -September 30. Winterize by October 31. 4. In the fall of 2017 all dead plants will be replaced with th e same species or an approved substitute species that meets the goal of the enhancement plan. Plant material shall meet the same spec ifications as originally-installed material. Replanting will not occur until after reason for failure has been identified (e.g., moisture reg ime, poor plant stock. disease. shade/sun cond itions . wildlife damage. etc.). Replanting shall be completed under the direction of the AOA. 7.0 SUMMARY & MONITORING SCHEDULE Overall. the site i s performing well at the time of construction. With proper o n -go ing m aintenance th e site should establish successfully. The next long-term monitoring event is schedu led for l ate April for the first quarterly review followed by subm ittal of a summary report to you. In the fall of next year, we will conduct the plant mortality assessment to determine if any additional plantings will need to be install ed prior to su bmittal of the third quarterly report to the City. Quarterly reporting will continue through January Rocale Timmons January 21. 2016 Page 7 of 7 2017. After Year 1, monitoring and reporting will then continue annually with reports submitted to the City annually in January through at least Year 5 (January 2021). We would like to receive written approval of construction and this report by the City as soon as possible. Should you have any questions. please call me at (425) 333-4535 or email me at simone@altoliver.com . Sincerely, ALTMANN OLIVER ASSOCIATES. LLC Simone Oliver Landscape Architect Attachments: 1. Sheet ABl of 1 -As-built Buffer Enhancement Plan cc: Paul Ebensteiner, Troy Bean, Jeff Lind -via email Associated Earth Sciences, Inc. D ~~c----i~ LU ~ t!:_J ~ Serving tlie 'Pacific Northwest Since 1981 December 16, 2013 Project No. KE130602A Lozier Development, LLC 1300 114'' Avenue SE, Suite 100 Bellevue, Washington 98004 Attention: Subject: Mr. Paul G. Ebensteiner Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Whitman Court Townhomes 351 Whitman Court NE Renton, Washington Dear Mr. Ebensteiner: 0 ;; r, ~., I. / < ' ,; ' I. , i ' iVI f-1,li ' We are pleased to present these copies of our preliminary report for the referenced project. This report summarizes the results of our subsurface exploration, geologic hazards, and geotechnical engineering studies, and offers preliminary recommendations for the design and development of the proposed project. Our report is preliminary since project plans were under development at the time this report was written. We should be allowed to review the recommendations presented in this report and modify them, if needed, once final project plans have been formulated. We have enjoyed working with you on this srudy and are confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions, or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland Washington Bruce L. Blyton, Senior Principal BLB/pc KE13D602A2 Projccls\20130602\KE\ WP Kirkland 425-827-770 I • Everett • Tacoma 425-259-0522 253-722-2992 www.aesgeo.com {Jeoteclinica{'Engineering Water '.Resources 'Environment a{ ..'Assessments ana '.Remediation Sustaina6{e VeveCoyment Services §eoCogic ..'Assessments Associated Earth Sciences, Inc. Serving tlie 'Pacific Nortliwest Since 1981 Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report WHITMAN COURT TOWNHOMES Renton, Washington Prepared for Lozier Development, LLC Project No. KEI30602A December 16, 2013 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS, AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT WHITMAN COURT TOWNHOMES Renton, Washington Prepared for: Lozier Development, LLC 1300 114th Avenue SE, Suite 100 Bellevue, Washington 98004 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 December 16, 2013 Project No. KE130602A Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Project and Site Conditions I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazards, and preliminary geotechnical engineering studies for the proposed Whitman Court Townhomes project. The site location is shown on the "Vicinity Map," Figure 1. The approximate locations of exploration pits completed for this study are shown on the "Site and Exploration Plan," Figure 2. Logs of the subsurface explorations completed for this study are included in the Appendix. 1.1 Purpose and Scope The purpose of this study was to provide geotechnical engineering design recommendations to be utilized in the preliminary design of the project. This study included a review of selected available geologic literature, excavation of six exploration pits, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow ground water. Geotechnical engineering studies were completed to establish recommendations for the type of suitable foundations and floors, allowable foundation soil bearing pressure, anticipated foundation and floor settlement, pavement subgrade recommendations, and drainage considerations. This report summarizes our fieldwork and offers preliminary recommendations based on our present understanding of the project. We recommend that we be allowed to review the recommendations presented in this report and revise them, if needed, when a project design has been finalized. 1.2 Authorization Our work was completed in general accordance with our scope of work and cost proposal dated November 8, 2013. This report has been prepared for the exclusive use of Lozier Development, LLC, and its agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. 2.0 PROJECT AND SITE DESCRIPTION This report is based on review of a conceptual site plan prepared by GMS Architectural Group. The project, as we understand it, consists of the construction of multifanrily residential housing, with associated access and parking, at the existing property located at 351 Whitman December 16, 2013 ASSOCIATED EARTH SCIENCES. INC. JPUpc -KEJ30602A2 -Projects\20JJ()(j(J2\KE\WP Page 1 Whitman Court Townhomes Renton, Washington Subswface Exploration, Geologic Hazards, and Preliminary Geotechnica/ Engineering Report Pro;ect and Site Conditions Court NE in Renton, Washington. In addition to the proposed housing, a bank building is planned for the northernmost portion of the site. We understand that previous grading activities have occurred at the subject site, including the construction of a storm water pond, and that the existing pond is currently under consideration to provide storm water storage for the currently-proposed project. Also, we understand that infiltration of storm water is currently under consideration for the area of the proposed bank at the north end of the site. The subject site encompasses three parcels (King County Parcel Nos. 5182100020, 5182100021, and 5182100022) totaling roughly 5.13 acres in size. The site fronts the south side of NE 4'" Street and the west side of Whitman Court. The topography of the site is generally flat-lying to gently sloping downward to the west and south, and is currently vegetated with grass. A wetland, delineated by others, is located along the western portion of the site. The southern portion of the site extends eastward, up a moderate slope, along the southern boundary of an adjacent post office property. The subject site appears to have been previously developed, with a storm water pond at the southwest portion of the site and utility stub-outs extending onto the site from Whitman Court. 3.0 SUBSURFACE EXPLORATION Our field study included excavating a series of exploration pits to gain subsurface information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Our explorations were approximately located in the field relative to known site features shown on the topographic site plan. The locations of the exploration pits are shown on Figure 2. The conclusions and recommendations presented in this report are based, in part, on the exploration pits completed for this study. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, interpolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. December 16, 2013 ASSOClATED EARm SCIENCES, INC. JPUpc -KEJ30602A2-Projects\20130602\KElWP Page 2 Whitman Court Townhomes Renton, Washington 3 .1 Exploration Pits Subswface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Pro;ect and Site Conditions Exploration pits were excavated with a track-mounted excavator. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by a representative from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of selected applicable geologic literature. Because of the nature of exploratory work below ground, interpolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. 4 .1 Stratigraphy Fill Fill soils (soils not naturally placed) were encountered at the locations of exploration pits EP-1 through EP-4 to depths ranging from 2 to 5 feet below the ground surface. Fill encountered generally consisted of loose to medium dense silty fine to coarse sand with gravel. The encountered fill generally included scattered organics, wood debris and, at exploration pits EP-1 and EP-4, other assorted debris, such as plastic pieces, concrete and rubber. At EP-1 through EP-3, the fill was underlain by a 6-inch-thick buried topsoil layer. The exact extent and depth of fills can vary widely over short distances. Fill is also expected in unexplored areas of the site. Due to their variable depth, density and organic content, we recommend that the existing fill soils be evaluated at the time of foundation excavation to determine the suitability of the existing fill for foundation support. Vashon Recessional Outwash At exploration pits EP-5 and EP-6, and below the fill at EP-1 through EP-4, Vashon recessional outwash sediments were encountered, extending to a depth of 7 .5 feet below the ground surface at EP-6, and beyond the depths explored of 8 to 12 feet below the ground surface at the remaining exploration pits. The outwash sediments were deposited by meltwater streams flowing from the receding Vashon glacier approximately 10,000 years ago. The December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL/pc -KEJ30602A2 -Projectsl20130602\KEIWP Page 3 Whitman Coun Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Repon Project and Site Conditions outwash material consisted primarily of a medium dense, moist to wet, fine to coarse sand with gravel, gravel beds, and varying amounts of silt. This unit is generally suitable for support of light to moderately loaded foundations and for pavement subbase when properly compacted as discussed in this report. Vashon Lodgement Till Sediments encountered below the Vashon recessional outwash at EP-6 generally consisted of very dense silty fine to medium sand with gravel. We interpret these sediments to be representative of Vashon lodgement till. The Vashon lodgement till was deposited directly from basal, debris-laden glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. The high relative density of the unweathered till is due to its consolidation by the massive weight of the glacial ice from which it was deposited. The Vashon lodgement till extended below the depth explored. 4.2 Geologic Mapping Review of the regional geologic map titled Geologic Map of King County, compiled by Derek B. Booth et al., dated May 2006, indicates that the area of the subject site is underlain by Vashon lodgement till (Qvt), with Vashon recessional outwash (Qvr) mapped in the vicinity. Our interpretation of the sediments encountered at the subject site is in general agreement with the regional geologic map. 4.3 Hydrology We encountered ground water seepage in exploration pits EP-1, EP-2 and EP-4 at depths of 10 feet, 11.5 feet and 10 feet, respectively, below the ground surface. We expect ground water seepage across much of the site to be limited to interflow. Interflow occurs when surface water percolates down through the surficial weathered or higher-permeability sediments and becomes perched atop underlying, lower-permeability sediments. It should be noted that the occurrence and level of ground water seepage at the site may vary in response to such factors as changes in season, precipitation, and site use. 4 .4 Laboratory Test Results Grain size analysis tests were completed on two samples selected from the explorations. Results are included in the Appendix. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. IPL/pc -KE130602A2 -Projects120/30602\KE\WP Page 4 Whitman Coun Townhomes Renton, Washington Subsu,face Exploration, Geologic Hazards, and Preliminary Geotechnica/ Engineering Repon Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic, slope, and ground and surface water conditions, as observed and discussed herein. The discussion will be limited to seismic and erosion issues. 5.0 SEISMIC HAZARDS AND MITIGATIONS Earthquakes occur regularly in the Puget Lowland. The majority of these events are small and are usually not felt by people. However, large earthquakes do occur, as evidenced by the 1949, 7.2-magnitude event; the 2001, 6.8-magnitude event; and the 1965, 6.5-magnitude event. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture, 2) seismically induced landslides, 3) liquefaction, and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 5 .1 Surficial Ground Rupture Based on the reviewed geologic map, the project site is located approximately 3 miles to the south of the Seattle Fault Zone. Recent studies by the U.S. Geological Survey (USGS) (e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, p.71-74; and Johnson et al., 1999, Active Tectonics of the Seattle Fault and Central Puget Sound Washington -Implications for Earthquake Hazards, Geological Society of America Bulletin, July 1999, v. 111, n. 7, p. 1042-1053) have provided evidence of snrficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault is relatively new, and data pertaining to it are limited, with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about 1,100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along this fault system is still unknown. However, due to the distance between the subject site and the Seattle Fault Zone, the potential for surficial ground rupture is considered to be low during the expected life of the structures, and no December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ30602A2 -Projects120!3V6021K£\WP Page 5 Whitman Coun Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations mitigation efforts beyond complying with the current 2012 International Building Code (IBC) are recommended. 5.2 Seismically Induced Landslides It is our opinion that the potential risk of damage to the proposed development by seismically induced slope failures is low due to the lack of steep slopes in the project area. 5. 3 Liquefaction Liquefaction is a process through which unconsolidated soil loses strength as a result of vibrations, such as those which occur during a seismic event. During normal conditions, the weight of the soil is supported by both grain-to-grain contacts and by the fluid pressure within the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the grain-to-grain contact, increase the pore pressure, and result in a temporary decrease in soil shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is supported by pore pressure alone. Liquefaction can result in deformation of the sediment and settlement of overlying structures. Areas most susceptible to liquefaction include those areas underlain by non-cohesive silt and sand with low relative densities, accompanied by a shallow water table. The subsurface conditions encountered at the site pose little risk of liquefaction due to relatively high density and lack of shallow ground water. No detailed liquefaction analysis was completed as part of this study, and none is warranted, in our opinion. 5 .4 Ground Motion Structural design of the buildings should follow 2012 IBC standards using Site Class "C" as defined in Table 20.3-1 of American Society of Civil Engineers (ASCE) 7 -Minimum Design Loads for Buildings and Other Structures. 6.0 EROSION HAZARDS AND MITIGATIONS As of October 1, 2008, the Washington State Departtnent of Ecology (Ecology) Construction Storm Water General Permit (also known as the National Pollutant Discharge Elimination System [NPDESJ permit) requires weekly Temporary Erosion and Sedimentation Control (TESC) inspections and turbidity monitoring of site runoff for all sites 1 or more acres in size that discharge storm water to surface waters of the state. We provide in the following sections recommendations to address these inspection and reporting requirements, should they be December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ30602A2-Projeclsl201306021KElWP Page 6 Whitman Court Townhomes Renton, Washington Subswface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations triggered. The following sections also include recommendations related to general erosion control and mitigation. The TESC inspections and turbidity monitoring of runoff must be completed by a Certified Erosion and Sediment Control Lead (CESCL) for the duration of the construction. The weekly TESC reports do not need to be sent to Ecology, but should be logged into the project Storm Water Pollution Prevention Plan (SWPPP). Ecology requires a monthly summary report of the turbidity monitoring results signed by the NPDES permit holder. If the monitored turbidity equals or exceeds 25 nephelometric turbidity units (NTU) (Ecology benchmark standard), the project best management practices (BMPs) should be modified to decrease the turbidity of storm water leaving the site. Changes and upgrades to the BMPs should be documented in the weekly TESC reports and continued until the weekly turbidity reading is 25 NTU or lower. If the monitored turbidity exceeds 250 NTU, the results must be reported to Ecology via phone within 24 hours and corrective actions should be implemented as soon as possible. Daily turbidity monitoring is continued until the corrective actions lower the turbidity to below 25 NTU, or until the discharge stops. This description of the sampling benchmarks and reporting requirements is a brief summary of the Construction Storm Water General Permit conditions. The general permit is available on the internet1 • In order to meet the current Ecology requirements, a properly developed, constructed, and maintained erosion control plan consistent with City of Renton standards and best management erosion control practices will be required for this project. Associated Earth Sciences, Inc. (AESI) is available to assist the project civil engineer in developing site-specific erosion control plans. Based on past experience, it will be necessary to make adjustments and provide additional measures to the TESC plan in order to optimize its effectiveness. Ultimately, the success of the TESC plan depends on a proactive approach to project planning and contractor implementation and maintenance. The most effective erosion control measure is the maintenance of adequate ground cover. During the local wet season (October I" through March 31 "), exposed soil should not remain uncovered for more than 2 days unless it is actively being worked. Ground-cover measures can include erosion control matting, plastic sheeting, straw mulch, crushed rock or recycled concrete, or mature hydroseed. Surface drainage control measures are also essential for collecting and controlling the site runoff. Flow paths across slopes should be kept to less than 50 feet in order to reduce the erosion and sediment transport potential of concentrated flow. Ditch/swale spacing will need to be shortened with increasing slope gradient. Ditches and swales that exceed a gradient of about 7 to 10 percent, depending on their flow length, should have properly constructed check dams installed to reduce the flow velocity of the runoff and reduce the erosion potential within 1 http://www.ecy. wa. gov /programs/wq/stormwater/consu-uction/constructionfinalpermit. pdf December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL/pc-KE130602A2 -Projectsl20I30602IKE\WP Page 7 Whitman Coun Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Repon Geologic Hazards and Mitigations the ditch. Flow paths that are required to be constructed on gradients between 10 to 15 percent should be placed in a riprap-lined swale with the riprap properly sized for the anticipated flow conditions. Flow paths constructed on slope gradients steeper than 15 percent should be placed in a pipe slope drain. AESI is available to assist the project civil engineer in developing a suitable erosion control plan with proper flow control. Silt fencing should be utilized as buffer protection and not as a flow-control measure. Silt fencing should be placed parallel with topographic contours to prevent sediment-laden runoff from leaving a work area or entering a sensitive area. Silt fences should not be placed to cross contour lines without having separate berm/swale flow control in front of the silt fence. 6 .1 Erosion Hazard Mitigation To mitigate the erosion hazards and potential for off-site sediment transport, we would recommend the following: 1. Construction activity should be scheduled or phased as much as possible to reduce the amount of earthwork activity that is performed during the winter months. 2. The winter performance of a site is dependent on a well-conceived plan for control of site erosion and storm water runoff. The TESC plan should include adequate ground- cover measures, access roads, and staging areas to maintain a workable site. The contractor should implement and maintain the required measures as necessary through all phases of site work. A site maintenance plan should be in place in the event storm water turbidity measurements are greater than the Ecology standards. 3. TESC measures for a given area to be graded or otherwise worked should be installed soon after ground clearing. The recommended sequence of construction within a given area after clearing would be to install sediment traps and/or ponds and establish perimeter flow control prior to starting mass grading. 4. During the wetter months of the year, or when large storm events are predicted during the summer months, each work area should be stabilized so that if showers occur, the work area can receive the rainfall without excessive erosion or sediment transport. The required measures for an area to be "buttoned-up" will depend on the time of year and the duration the area will be left un-worked. During the winter months, areas that are to be left un-worked for more than 2 days should be mulched or covered with plastic. During the summer months, stabilization will usually consist of seal-rolling the subgrade. Such measures will aid in the contractor's ability to get back into a work area after a storm event. The stabilization process also includes establishing temporary December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL!pc ~ KEJ30602A2 ~ Projects120130602\KEIWP Page 8 Whitman Court Townhomes Renton, Washington Subsuiface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations storm water conveyance channels through work areas to route runoff to the approved treatment facilities. 5. All disturbed areas should be revegetated as soon as possible. If it is outside of the growing season, the disturbed areas should be covered with mulch, as recommended in the erosion control plan. Straw mulch provides a cost-effective cover measure and can be made wind-resistant with the application of a tackifier after it is placed. 6. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. Under no circumstances should concentrated discharges be allowed to flow over the top of steep slopes. 7. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of silt fences around pile perimeters. During the period between October 1" and March 31 ", these measures are required. 8. On-site erosion control inspections and turbidity monitoring (if required) should be performed in accordance with Ecology requirements. Weekly and monthly reporting to Ecology should be performed on a regularly scheduled basis. A discussion of temporary erosion control and site runoff monitoring should be part of the weekly construction team meetings. Temporary and permanent erosion control and drainage measures should be adjusted and maintained, as necessary, for the duration of project construction. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate mitigation elements (BMPs) throughout construction, as recommended by the erosion control inspector, the potential adverse impacts from erosion hazards on the project may be mitigated. December 16, 2013 ASSOCIATED EARlli SCIENCES, INC. JPUpc-KE130602A.2 -Projects\20130602\KE\WP Page 9 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnica/ Engineering Report Preliminary Design Recommendations III. PRELIMINARY DESIGN RECOMMENDATIONS 7 .0 INTRODUCTION Our exploration indicates that, from a geotechnical standpoint, the parcel is suitable for the proposed development provided the recommendations contained herein are properly followed. The foundation bearing stratum is relatively shallow, and conventional spread footing foundations may be utilized for the proposed structure. Consequently, foundations bearing on either the medium dense to very dense natural sediments, or on structural fill placed over these sediments, are capable of providing suitable building support. The infiltration of storm water into the soils underlying the ft!! encountered below the proposed parking area for the bank at the north end of the site may be feasible based on our preliminary explorations and laboratory testing. The site is underlain by existing fill material which varies in thickness, density, and content. Based on this variability, we recommend that the foundation sub grade soils be evaluated during excavation to determine the suitability of the existing fill for foundation support. If foundation areas determined to be underlain by existing fill that are deemed unsuitable for foundation support, we recommend that the existing fill be removed and replaced, as described in the following sections of this report. 8.0 SITE PREPARATION Existing buried utilities, vegetation, topsoil, and any other deleterious materials should be removed where they are located below planned construction areas. All disturbed soils should be removed to expose underlying, undisturbed, native sediments and replaced with structural fill, as needed. All excavations below final grade made for clearing and grubbing activities should be backfilled, as needed, with structural fill. Erosion and surface water control should be established around the clearing limits to satisfy local requirements. Once clearing and grubbing activities have been completed, existing fill, where encountered, should be addressed. We recommend that existing fill be removed from below areas of planned foundations to expose underlying, undisturbed native sediments, followed by restoration of the planned foundation grade with structural fill. Where deemed necessary removal of existing fill should extend laterally beyond the building footprint by a distance equal to the depth of overexcavation. For example, if existing fill is removed to a depth of 2 feet below a planned footing area, the excavation should also extend laterally 2 feet beyond the building footprint in that area. Care should be taken not to disturb support soils of existing foundations. Support soils should be considered those soils within a prism projected December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ30602A2 -Projecrs\2013l\i021KE1WP Page 10 Whitman Court Townhomes Renton, Washington Subswface Exploration, Geologic Hazards, a,uJ Preliminary Geotechnica/ Engineering Report Preliminary Design Recommendations downward and outward from existing footings at inclinations of lH:lV (Horizontal:Vertical). Where existing fill must be removed and replaced with structural fill, conventional shallow foundations may be used for building support. The required depth and extent of removal should be determined by an AES! representative in the field based on actual conditions encountered during excavation. 8 .1 Site Drainage and Surface Water Control The site should be graded to prevent water from ponding in construction areas and/or flowing into excavations. Exposed grades should be crowned, sloped, and smooth drum-rolled at the end of each day to facilitate drainage. Accumulated water must be removed from subgrades and work areas immediately prior to performing further work in the area. Equipment access may be limited, and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely sequence. If an effective drainage system is not utilized, project delays and increased costs could be incurred due to the greater quantities of wet and unsuitable fill, or poor access and unstable conditions. We anticipate that perched ground water could be encountered in excavations completed during construction. We do not anticipate the need for extensive dewatering in advance of excavations. The contractor should be prepared to intercept any ground water seepage entering the excavations and route it to a suitable discharge location. Final exterior grades should promote free and positive drainage away from the building at all times. Water must not be allowed to pond or to collect adjacent to foundations or within the immediate building area. We recommend that a gradient of at least 3 percent for a minimum distance of 10 feet from the building perimeters be provided, except in paved locations. In paved locations, a minimum gradient of 1 percent should be provided, unless provisions are included for collection and disposal of surface water adjacent to the structures. 8. 2 Sub grade Protection To the extent that it is possible, existing pavement should be used for construction of staging areas. If building construction will proceed during the winter, we recommend the use of a working surface of sand and gravel, crushed rock, or quarry spalls to protect exposed soils, particular! y in areas supporting concentrated equipment traffic. In winter construction staging areas and areas that will be subjected to repeated heavy loads, such as those that occur during construction of masonry walls, a minimum thickness of 12 inches of quarry spalls or 18 inches of pit run sand and gravel is recommended. If subgrade conditions are soft and silty, a geotextile separation fabric, such as Mirafi 500X or approved equivalent, should be used between the subgrade and the new fill. For building pads where floor slabs and foundation construction will be completed in the winter, a similar working surface should be used, December 16, 2013 ASSOClATED EARTH SClENCES, ENC. JPUpc -KE/30602A2 -Projecls\20/ 30602\KE\ WP Page II Whitman Coun Townhomes Renton, Washington Subswface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Repon Preliminary Design Recommendations composed of at least 6 inches of pit run sand and gravel or crushed rock. Construction of working surfaces from advancing fill pads could be used to avoid directly exposing the subgrade soils to vehicular traffic. Foundation subgrades may require protection from foot and equipment traffic and ponding of runoff during wet weather conditions, Typically, compacted crushed rock or a lean-mix concrete mat placed over a properly prepared subgrade provides adequate subgrade protection. Foundation concrete should be placed and excavations backfilled as soon as possible to protect the bearing surface. 8.3 Proof-Rolling and Subgrade Compaction Following the recommended clearing, site stripping, and planned excavation, the stripped subgrade within the building areas should be proof-rolled with heavy, rubber-tired construction equipment, such as a fully loaded, tandem-axle dump truck. Proof-rolling should be performed prior to structural fill placement or foundation excavation. The proof-roll should be monitored by the geotechnical engineer so that any soft or yielding subgrade soils can be identified. Any soft/loose, yielding soils should be removed to a stable subgrade. The subgrade should then be scarified, adjusted in moisture content, and recompacted to the required density. Proof-rolling should only be attempted if soil moisture contents are at or near optimum moisture content. Proof-rolling of wet subgrades could result in further degradation. Low areas and excavations may then be raised to the planned finished grade with compacted structural fill. Subgrade preparation and selection, placement, and compaction of structural fill should be performed under engineering-controlled conditions in accordance with the project specifications. 8.4 Overexcavation/Stabilization Construction during extended wet weather periods could create the need to overexcavate exposed soils if they become disturbed and cannot be recompacted due to elevated moisture content and/or weather conditions. Even during dry weather periods, soft/wet soils, which may need to be overexcavated, may be encountered in some portions of the site. If overexcavation is necessary, it should be confirmed through continuous observation and testing by AES!. Soils that have become unstable may require remedial measures in the form of one or more of the following: I. Drying and recompaction. Selective drying may be accomplished by scarifying or windrowing surficial material during extended periods of dry and warm weather. 2. Removal of affected soils to expose a suitable bearing subgrade and replacement with compacted structural fill. December 16, 2013 ASSOCIATED EARlli SCIENCES, INC. JP Lipe -KEJ 30602A2 -Projec/s\20130602\KE\ WP Page 12 Whitman Court Townhomes Renton, Washington Subswface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations 3. Mechanical stabilization with a coarse crushed aggregate compacted into the subgrade, possibly in conjunction with a geotextile. 4. Soil/cement admixture stabilization. 8.5 Wet Weather Conditions If construction proceeds during an extended wet weather construction period and the moisture-sensitive site soils become wet, they will become unstable. Therefore, the budget for site grading operations should consider the time of year that construction will proceed. It is expected that in wet conditions additional soils may need to be removed and/or other stabilization methods used, such as a coarse crushed rock working mat to develop a stable condition if silty subgrade soils are disturbed in the presence of excess moisture. The severity of construction disturbance will be dependent, in part, on the precautions that are taken by the contractor to protect the moisture-and disturbance-sensitive site soils. If overexcavation is necessary, it should be confirmed through continuous observation and testing by a representative of our firm. 8.6 Temporary and Permanent Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, we anticipate that temporary, unsupported cut slopes in the existing fill or recessional outwash can be made at a maximum slope of I.SH: 1 V or flatter. Temporary slopes in lodgement till deposits may be planned at lH:IV. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. If ground water seepage is encountered in cut slopes, or if surface water is not routed away from temporary cut slope faces, flatter slopes will be required. In addition, WISHA/OSHA regulations should be followed at all times. Permanent cut and structural fill slopes that are not intended to be exposed to surface water should be designed at inclinations of 2H: 1 V or flatter. All permanent cut or fill slopes should be compacted to at least 95 percent of the modified Proctor maximum dry density, as determined by American Society for Testing and Materials (ASTM):D 1557, and the slopes should be protected from erosion by sheet plastic until vegetation cover can be established during favorable weather. 8. 7 Frozen Sub grades If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw and then be recompacted prior to placing subsequent lifts of structural fill or foundation components. Alternatively, the frozen material could be stripped from the subgrade to reveal unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. December 16, 2013 ASSOCIATED EAR11l SCIENCES, INC. JPllpc-KCJ30W2A2-Projects\20130602lKE\WP Page 13 Whitman Coun Townhomes RenJon, Washington 9.0 STRUCTURAL FILL Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnica/ Engineering Repon Preliminary Design Recommendations All references to structural fill in this report refer to subgrade preparation, fill type and placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer, the upper 12 inches of exposed ground in areas to receive fill should be recompacted to 90 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. If the subgrade contains silty soils and too much moisture, adequate recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current City of Renton codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the locations of the roadway edges before sloping down at an angle of2H:1V. The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material 72 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions. The native and existing fill soils present on-site contained variable amounts of silt and are considered moisture-sensitive. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction with at least 25 percent retained on the No. 4 sieve. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ 30602A2 -Projects\20130602\KE\ WP Page 14 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnica/ Engineering Report Preliminary Design Recommendations A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses, and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid in developing a suitable monitoring and testing program. 10.0 FOUNDATIONS For footings bearing directly on the medium dense to very dense natural sediments, or on structural fill placed over these materials, as described above, we recommend that an allowable foundation soil bearing pressure of 2,500 pounds per square foot (psi) be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection. However, all footings must penetrate to the prescribed bearing stratum, and no footing should be founded in or above organic or loose soils. All footings should have a minimum width of 18 inches. It should be noted that the area bound by lines extending downward at lH: 1 V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM:D 1557. In addition, a l.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded as described above should be on the order of l4 inch or less. However, disturbed or otherwise unsuitable soil not removed from footing excavations prior to footing placement could reslilt in increased settlements. All footing areas should be inspected by AESI prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the "Drainage Considerations" section of this report. 10.1 Drainage Considerations Foundations should be provided with foundation drains placed at the base of footing elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KE130602A2 -Projectsl20130602lKEIWP Page 15 Whit111£1n Court Townhomes Remon, Washington Subsuiface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations washed pea gravel. The drains should be constructed with sufficient gradient to allow gravity discharge away from the proposed building. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the proposed structure to achieve surface drainage. 11.0 FLOOR SUPPORT Floor slabs can be supported on suitable native sediments, or on structural fill placed above suitable native sediments. Floor slabs should be cast atop a minimum of 4 inches of clean, washed, crushed rock (such as '!,-inch "chip") or pea gravel to act as a capillary break. Areas of subgrade that are disturbed (loosened) during construction should be compacted to a non-yielding condition prior to placement of capillary break material. Floor slabs should also be protected from dampness by an impervious moisture barrier at least 10 mils thick. The moisture barrier should be placed between the capillary break material and the concrete slab. 12.0 FOUNDATION WALLS All backfill behind foundation walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed using an equivalent fluid equal to 35 pounds per cubic foot (pct). Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. Walls with sloping backfill up to a maximum gradient of 2H: IV should be designed using an equivalent fluid of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. As required by the 2012 IBC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall backfill materials, we recommend a seismic surcharge pressure of 5H and !OH psf, where H is the wall height in feet for the "active" and "at-rest" loading conditions, respectively. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the mid-point of the walls. The lateral pressures presented above are based on the conditions of a uniform backfill consisting of excavated on-site soils, or imported structural fill compacted to 90 percent of ASTM:D 1557. A higher degree of compaction is not recommended, as this will increase the pressure acting on the walls. A lower compaction may result in settlement of the slab-on-grade December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL/pc -KEJ30602A2 -ProjectslW1306021KE\WP Page 16 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendmions or other strucrures supported above the walls. Thus, the compaction level is critical and must be tested by our firm during placement. Surcharges from adjacent footings or heavy construction equipment must be added to the above values. Perimeter footing drains should be provided for all retaining walls, as discussed under the "Drainage Considerations" section of this report. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum, 1-foot-wide blanket drain to within 1 foot of finish grade for the full wall height using imported, washed gravel against the walls. A prefabricated drainage mat is not a suitable substirute for the gravel blanket drain unless all backfill against the wall is free-draining. 12.1 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the narural glacial soils or supporting strucrural fill soils, and by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with strucrural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following allowable design parameters: • Passive equivalent fluid = 350 pcf • Coefficient of friction = 0. 30 13.0 DRAINAGE CONSIDERATIONS All retaining and perimeter foundation walls should be provided with a drain at the base of the footing elevation. Drains should consist of rigid, perforated, PVC pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set at or slightly below the bottom of the footing grade beam, and the drains should be constructed with sufficient gradient to allow gravity discharge away from the buildings. In addition, all retaining walls should be lined with a minimum, 12-inch-thick, washed gravel blanket that extends to within 1 foot of the surface and is continuous with the foundation drain. Roof and surface runoff should not discharge into the foundation drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the strucrures to achieve surface drainage. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEI30602A2 -Project.s\20130602\KE\WP Page 17 Whitman Court Townhomes Renton, Washington Subsu,face Exploration, Geologic Hazard,, and Preliminary Geotechnica/ Engineering Report Preliminary Design Recommendations 14.0 PRELIMINARY INFILTRATION EVALUATION Much of the subject site is underlain by fill material that is not a suitable infiltration receptor. However, the grain-size analysis test results for samples collected below the fill at the proposed bank parking area at the north end of the site indicate fines contents ranging from roughly 8 to 9 percent of the fraction passing the No. 10 sieve. The classification of the samples tested most closely fits the texture class "sand" referenced in Table 3.7 in the 2005 Washington State Department of Ecology Stormwater Management Manual for Western Washington (Ecology Manual). For preliminary planning purposes only, this material has an uncorrected short-term infiltration rate of 8 inches per hour, with an Estimated Design (long-term) Infiltration Rate of 2 inches per hour. Should a design infiltration rate be needed for site-specific design, we recommend that AESI perform infiltration testing using a large-diameter infiltrometer, generally corresponding to the procedure described as a pilot infiltration test (PIT) in the Ecology Manual, at the proposed infiltration location(s) prior to final design in order to provide site-specific rates of infiltration. The PIT test(s) should take place at the bottom elevation of the proposed infiltration system. AESI is also available to conduct cation exchange capacity or organic content testing of site soils for in situ treatment of storm water, if requested. The suitability for the infiltration of storm water can be limited by the presence of a seasonal high water table. For seasonal high water table monitoring, we recommend that AESI install a pressure transducer connected to an automatic data logger in a well point which would be installed to less than 10 feet in depth. After the well point has been completed, we will develop the well and record the initial depth to ground water. The data logger would record hourly water levels, and would be installed and left in place for up to approximately I year to capture ground water levels during the coming winter and the following summer. Bimonthly hand measurements of the water level in the well would be collected in conjunction with downloading of water level data recorded by the data logger. The data would be downloaded, entered into a spreadsheet, compensated for barometric pressure effects, and calibrated with the manual water level measurements. 15.0 PAVEMENT SUBGRADE RECOMMENDATIONS Site preparation for areas to be paved should consist of excavating to remove the topsoil and the loose portion of the upper soils, exposing the underlying stable sediments. Since the density of the upper soils is variable, random loose areas may exist, and the depth and extent of stripping can best be determined in the field by the geotechnical engineer. In addition, the subgrade should be slightly crowned to drain toward the edges of the paved area. After the area to be paved is excavated, the exposed ground should be recompacted to at least 95 percent December 16, 2013 ASSOCIATED EARlli SCIENCES, INC. JPUpc -KEJ30602A2 -Projects\20130602\KE\WP Page 18 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations of ASTM:D 1557. If required, structural fill may then be placed to achieve desired subbase grades. The appropriate pavement section may then be placed over the prepared subgrade. 16.0 PROJECT DESIGN AND CONSTRUCTION MONITORING Our report is preliminary since project plans were not finalized at the time this report was written. We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, we can confirm that our earthwork and foundation recommendations have been properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction, The integrity of the foundation system depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know, and we will prepare a cost proposal. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Jeffrey P.ub,L.G., L.E.G. Senior Project Engineering Geologist Attachments: Figure 1: Figure 2: Appendix: December 16, 2013 Vicinity Map Site and Exploration Plan Exploration Logs Laboratory Testing JPUpc-KEJ30602A2-Projecu\20!30602\KE\WP Bruce L. Blyton, P.E. Senior Principal Engineer ASSOCIATED EARTH SCIENCES, INC. Page 19 I J J 5 ~ ',',r 26' 0 REFERENCE: USGS TOPO! 1000 FEET -~ . /; ... . . 2000 f Associated Earth Sciences, Inc. VICINITY MAP FIGURE 1 I@ I ! I ~ l:i"":J lt'Jlliil WHITMAN COURT TOWNHOMES DATE 11/13 ~ ~ IBJ n...J RENTON, WASHINGTON PROJ. NO. KE130602A -------------------------------------- '""""'-• ksio;,~---r--:--- _1 ·t3., i LllHl '11J,0;111l APPROXIMATE LOCATION OF EXPLORATION PIT TYP i i REFERENCE: GMS ARCHITECTURAL GROUP o F:T !======================== 80 J Associated Earth Sciences, Inc. I Ill C:i9 i.l iii Ill SITE AND EXPLORATION PLAN WHITMAN COURTTOWNHOMES RENTON, WASHINGTON FIGURE 2 DATE 11/13 PROJ. NO. KE130602A APPENDIX . m 'C C m Cl) .. 0 > ., ~ C w m 0 >-5 i:l .!!! ii! () .. ci "-' z c., ill m E m 11 :::J m Cl) 'C &. s e g 0 " ~ _o ,:. .... 0 e ., 0 .!!l rt.:, 0 .!!! Q Cl) ~g 'C .. C" ~ m E J/l :::J (!) = 'C ~ "'s Li: 5 .2' .2 VJ .C C -.23mo I gUJ Poorly-graded gravel and gravel with sand, little to no fines Silly gravel and silty GM gravel with sand Clayey gravel and Gc clayey gravel with sand Well-graded sand and sw sand with gravel, little to no fines Poorly-graded sand SP and sand with gravel, little to no fines SIity sand and SM silty sand with · gravel Clayey sand and SC clayey sand with gravel Slit, sandy silt, gravelly silt, ML slit with sand or gravel CL Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Organic ctay or silt of low OL plasticity Terms Describing Relative Density and Consistency Coarse- Gralned Soils Density Very Loose Loose Medium Dense Dense Very Dense SPT121 blows/foot Oto4 4 to 10 1010 30 30 to 50 >50 Test Symbols G = Grain Size Consistency SPT12 t>lows/foot Oto2 M = Moisture Content A = Atterberg Limits C = Chemical Fine~ Grained Soils Very Solt Solt Medium Stttf Stiff Very Stttf Hard 2to4 DD = Dry Density 4 to8 K -Permeability 8 to 15 15 to 30 >30 Descriptive Term Boulders Component Definitions Size Range and Sieve Number Larger than 12' Cobbles 3' to 12' Gravel Coarse Gravel Fine Gravel 3' to No. 4 (4.75 mm) 3'to3/4' 3/4' 1o No. 4 (4.75 mm) Sand Coarse Sand Medium Sand Fine Sand No. 4 (4. 75 mm) to No. 200 (0.075 mm) No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 10 (2.00 mm) to No. 40 (0.425 mm) No. 40 (0.425 mm) to No. 200 (0.075 mm) Sill and Clay Smaller than No. 200 (0.075 mm) (3) Estimated Percentage Component Percentage by Weight Trace <5 Few 51010 Utile 15 to25 With -Non-primary coarse constituents: _2: 15% -Fines content between 5% and 15% Moisture Content 01)' -Absence of moisture, dusty, dry to the loucll Slightly Moist· Perceptible moisture Moist -Damp but no visible water Very Moist -Water visible but not free draining Wet -Vlslble free waler, usually from below water table Symbols Blows/6'-or portion of fl' Sampler Type Elastic silt, clayey slit, silt 2_0, 00 MH with micaceous or Split-Spoon I " " Sampler Type Description Cement groul surface seal Bentonlte seal • (<) dlatomaceous fine sand or Sampler ...__._..si,.,_it ______ __, (SPT) 3.0' OD Splil-Spoon Sampler :. FIiter pack with ·":· blank casing Clay of high plasticity, 3.25' OD Split-Spoon Ring Sampler · •. section CH sandy or gravelly ctay, fat Bulk sample ctay with sand or gravel • 3.0' OD Thin-Wall Tube Sampler (Including Shelby tube) ·: Screened casing :-· or Hydrotlp ·: with filler pack •• Endcap o Portion not recovered ~I Percentage by dry weight c'i'l--+----------1 I~ (SPT) Standard Penetration Test (ASTM D-1586) PT 13) In General Accordance with Standard Practice for Descrlption ("1) Depth of ground water !' ATD = At time of drllllng ~ Static water level (date) (SI Combined USCS symbols used for fines between 5% and 15% and Identification of Solis (ASTM 0,2488) l · Classlflcatfons of solls In this report are based on visual field and/or laboratory observations, which Include density/consistency, moisture condition, grain size, and· plssliclty es Um ates and should not be construed lo Imply fleld or laboratory lesllng unless presented herein. Visual-manual and/or laboratory ciassfflcatlon a methods of ASTM 0~2487 and D-2488 ware used as an ldenttflcallon guide for the Unified Sofl ClasslficaUon System. 5===================================== i ~ Associated Earth Sciences, Inc. EXPLORATION LOG KEY FIGURE A1 I -------------------------------------------- LOG OF EXPLORATION PIT NO. EP-1 _,.,.·-----------------------------------~ This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Fill Loose to medium dense, moist, brown and gray, silty fine to coarse SAND, with gravel, scattered 1 -organics, burned wood fragments, plastic and rubber pieces, concrete. 2 - 3 - 4 - 5 6 - 7 - 8 - 9 - 10 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Burled Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown (5.5 to 6.5 feet) to brown, fine to coarse SAND, with gravel. Medium dense, moist to wet, brownish gray, GRAVEL, with sand, with silt. --------------------------------- Bottom of exploration pit at depth 1 O feet Seepage at 1 O feet. No caving. ~-----2()----------------------------------~--------------------------------------------,n I j l;' Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. ~9~1:P!l~ ~UJ~lalY~ Project No. KE130602A 11/21/13 ~ ----------------------------- LOG OF EXPLORATION PIT NO. EP-2 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESl) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Fill Loose to medium dense, moist, brown and gray, silty fine to coarse SAND, with gravel, wood debris 1 -and scattered organics. 2 - 3-+---------------~~=-~---------------Buried Topsoil 4 -, 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Vashon Recessional Outwash Loose to medium dense, moist, reddish brown (3.5 to 4.5 feet) to brown, fine to coarse SAND, with gravel. Bottom of exploration pit at depth 11.5 feet Seepage at 11.5 feet. No caving. M---fl.&-_--------------------------__:___: ~--------------------------------------------'" j ~ " ~ Logged by; JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ~ ----------------------------- € £ 5)- 0 LOG OF EXPLORATION PIT NO. EP-3 ------------------------------------- This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI} tor the named project and should ba read together with that report for complete interpretation. This summary applies only to the location of this trench at tho time of excavation. Subsurface conditions may change al !his location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Fill Loose to medium dense, moist, brown and gray, silty fine to coarse SAND, with gravel, wood debris 1 -and scattered organics. 2 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - Burled Topsoil 1---------------------------'------------------ Vashon Recessional Outwash Loose to medium dense, moist, reddish brown, silty SAND, with gravel. Medium dense, moist, brownish gravel, fine to medium SAND, trace gravel. Medium dense, moist, brownish gray, GRAVEL, with fine to coarse sand. 11 -Medium dense, moist, brownish gray, fine to medium SAND, with silt, with gravel. 12 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 12 feet No seepage. Caving 4 to 6 feet. ~-~20&----0 ,--------------------------------------------.. _ij E ~ Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. ~ ~ ~ [:p'I] W1iil ~~~~~ Project No. KE130602A 11/21/13 ~ ----------------------------------- LOG OF EXPLORATION PIT NO. EP-4 ~--------··-----------------------------------~~ This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that repqrt for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsuriace conditions may change at this location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Fill . Loose to medium dense, moist, brownish gray, silty SAND, with gravel. 1 - 2 - Loose to medium dense, moist, brown, silty SAND, with gravel, with wood debris, plastic, concrete, 3 -and scattered organics. 4 e-----------------=~-~--~~~--~-------------Vashon Recessional Outwash 5 -Loose to medium dense, moist, reddish brown, fine to medium SAND, with silt, with gravel. 6 - 7 - 8 - 9 - 10 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Loose to medium dense, moist to wet, brown, fine to medium SAND, with silt, with gravel. Bottom of exploration pit at depth 1 a feet Seepage al 1 o feet. No caving. ~---lIB----------------------------------0 ·--------------------------------------------,,; j § ~ ~ Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ~ ----------------------------- 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-5 This log is part of the report prepared by Associated Earth Sciences, Inc. {AESI) for the named project and should be read together with that report for complete interpretation. This summary applles only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown, fine to medium SAND, with gravel. Medium dense, moist, brownish gray, fine to medium SAND, with gravel. Medium dense, moist, brownish gray, fine to coarse SAND, trace gravel. Bottom of exploration pit at depth 8 feet No seepage. No caving. ~--l!f-)-----------------------------------------~--------------------------------------------"' I ~ ;;: ~ I Logged by; JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ~ ----------------------------------- 1 - 2 - 3 4 - 5 - 6 - 7 - LOG OF EXPLORATION PIT NO. EP-6 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESJ) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsuriace conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown to brown, fine to medium SAND, with silt, with gravel, with roots. Medium dense, moist, brownish gray, fine to medium SAND, with gravel. Vashon Lodgement Till 8 -Very dense, moist, brownish gray, silty fine to medium SAND, with gravel. 9 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 9 feet No seepage. No caving. ~---22&0----------------------------------~--------------------------------------------oi Ji E ! ~ Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE1 30602A 11/21/13 ----------------------------------- Date Sampled 12/6/2013 Tested By MS Wt. of moisture d Wt. of Tare Wt. of moisture D Moisture% Sieve No. ~ C u: 1: • ~ • Q. 3 2.5 2 1.5 1 3/4 3/8 #4 #8 #10 #20 #40 #60 #100 #200 #270 100 ! 80 60 40 20 0 100 3• i I GRAIN SIZE ANALYSIS • MECHANICAL Project Project No. Soil Description Whitman Court Townhomes KE130602A Gravel with sand trace silt Location EB/EP No 'Depth Onsite EP-1 7' .434.67 Total Sample Tare :.::42_.it-2-L Total Sample wt + tare ·.1683,!li .. 100.61 · ·: :: -. Total Sample Wt 1385.2 323.6 Total Sample Dry Wt 1341.0 3% Snecificatlon Renuirements Diam. Imm\ Wt. Retained ,n, % Retained % Passina Minimum Maximum 76.1 :: . --·~ .. •,,., 0.0 100.0 --,a •• , ••• -. 64 ·.·· . : 0.0 100.0 -. 50.8 ... .. ·.··· .. 0.0 100.0 -- 38.1 137:39 .. 10.2 89.8 -- 25.4 410.38 •. -30.6 69.4 -- 19 •599:i)'e·· ... 44.7 55.3 9.51 707.62 . :. 52.8 47.2 4.76 · 780.38 58.2 41.8 2.38 -·· · -901,93 67.3 32.7 2 .. 934,53: ... • 69.7 30.3 0.85 _:···;·: 1059,75: ' 79.0 21.0 0.42 : :· :·12:1'3,,17: ,::·: 90.5 9.5 0.25 · :·.:1-2-72.61'' ':~ .:-94.9 5.1 0.149 ,i''f291)19 ;· ... 96.3 3.7 0.074 :· ... 'A30!t5B ·:::: 97.3 2.7 0.053 . . : ·1~or;1:a,, :c::: 97.5 2.5 US STANDARD SIEVE NOS. N0.4 N0.16 N0.40 N0.200 ' ' ~ ' ll,,,,.._ ..... ....... -.... i ~ ... .. 10 0.1 0.01 Gravel Sand Silt and Clay Coarse I Fine Coarse I Medium I Fine Grain Size, mm ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave., Suite 100 Kirkland, WA 96033 425-827-7701 FAX 425-827-5424 GRAIN SIZE ANALYSIS -MECHANICAL Date Sampled Project Project No. Soil Description 12/6/2013 Whitman Court Town homes KE130602A Gravel with sand trace silt Tested By Location EB/EP No 'Depth MS Onslte EP-1 9.5' Wt. of moisture wet sample+ Tare 424.15 Total Sam le Tare · aeM4 Wt. of moisture dry Sam le+ Tare 403:07 Total Sample wt + tare '1450:55. Wt. of Tare Wt. of moisture D Moisture% Sieve No. a; C i! ~ C ~ w D. 3 2.5 2 1.5 1 314 318 #4 #8 #10 #20 #40 #60 #100 #200 #270 100 80 60 40 20 0 100 3" 98.15 Total Sample WI 1056.6 Sample 304.92 Total Sample Dry WI 988.3 7% Soecification Reauirements Diam. lmml Wt. Retained 10, % Retained % Passino Minimum Maximum 76.1 .. , .......... a.a 100.0 --... -.·--. -.-.},':'.:c.,::c"·=.-··-- 64 -~ ·__ -_ :· ·: . _;-_ -:-0.0 100.0 -- 50.8 -0.0 100.0 ----~ --~ ·--~ ~~-· 38.1 .··, 132'.~ll"'·'·;· 13.4 86.6 -- 25.4 175.94, . · 17.8 82.2 -- 19 · 261;46 · .. ·. 26.5 73.5 9.51 458.66 46.4 53.6 4.76 617.45 ·. 62.5 37.5 2.38 707.26 . 71.6 28.4 2 · •.· .. 726.86 •.. 73.4 26.6 0.85 . ···.· SOi'l:13 . 81.6 18.4 0.42 . ·89Z.6<P' -, 90.3 9.7 0.25 . C.9!1t:52··c,,'' 95.3 4.7 0.149 954;51-• · "" 96.6 3.4 0.074 , __ ._._· 961.94 . 97.3 2.7 0.053 .. --964' . 97.5 2.5 US STANDARD SIEVE NOS. 3/4" N0.4 N0.16 N0.40 N0.200 ~ ' -.. ---------... ... II. ' .. " ~ ... l'o,,. ----- "'"' ~ -.. i 10 0.1 0.01 Gravel Sand Silt and Clay Coarse I Fine Coarse I Medium I Fine Grain Size, mm ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave., Sulle 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424 · SHANNONbWILSON.INC. . . . , .\. Wetrand Oelln&alion Ribera Balko Short Plat Renton, Washlnglon September 7. 2006 J)L." 1 '\ i. MAR 07 20:1 Submitted To: Mr. Tom Foster Fourth Avenue Associates, LLC 6450 Southcenter Blvd., Suite 106 Seatue. Washington 98188 By: Shannon & Wilson. Inc. 400 N 34'" Street, Suite 100 Seattle, Washington 98103 21-1-12193--001 t- t l i., .. 1 ' 11!1 . ~ >ii! .°j "" 1 ""' ..• ... •; "·" .... •• <f,1 " '" ... 'L:J -~ ,,. , ... ~ .. " . '"' :.(~ "' ;<! "" ''.;6 .. .c, .; Ill ,,t • ' l& ~-; ill [ ~ -~ 1!11 l \UI.E OF co:-;n;-.Ts IO I\ I H< •Ill ·1 · rin:,.; . J l ~L,lf'C nr S~·r\.t\,'.i..',;. 1.2 Srn .. · I PG1U~1u ~rnd lk~,:npt\Pn .... ~ o \ 11:'l llOl)S .. .1.11 llO( ·1 :\q,:,,1 Rl'\'IFW 4.il \\'f'Tl..'\:-.:D .·\l<l:,·\S .•\\I) srnl'.-\\1.. 4.1 \\',·tlnml .-\ ... 4.2 \\,·1laml IL. ·U l 'plamls ""4.4 S1n-;un ............ . ,.11 \\T·,·1..1:-.:IJ -\;,.;l) STRE,\\·1 HFGl 'l..\TIO\S . 5.1 \\.l'il,tnd R,llin,g d\ld Buft\.·r:-. ... 5.2 Sln.\1111 Buff,..:r:-..... 6.0 CUN "RE .... ~u REFl(Rf:-.:t·rs ...... . LIST OF Fl{;UffS Fi~urc "o, \'ii:inily \fap 2 '.\'ntlona.l \\\..·lland lnYcntnry !vfop .1 Soils \lap -1 \\'ctlanu Ddinentinn Map LIST OF APPENDICES Appendix A Wetland Ddincation Methodology B Wetland Field Darn Sheets SHANNON &WILSON. INC. . I . ... 1 .. I ' ........ 1 .. 4 . ..... 4 5 . ............ 5 .................. Ii ...... 7 .. ... 7 ..6 ...... 7 ...... " ................ .,I} C Important lnfonnation About Your Wetland Delineation and/or Stream Classification Report 21-1-12193-001 -"'.,{i..~·-· ; f. : , Ml ft '., ~ ' I I m I i ij ·:-: I •! I ~ . --~ ~ ii :~. u ' i -i j ·• • \\'f: II .\'ill DFI.IKl-:.\TIO:\ l{fllfR-\ lhl i.;o Sltoll.T l't .. \l RF:>i l'O'i. \VASl(l:>itao:,; 1.0 LYIROlll '('TIO,\ SHANNON &WILSON. INC. Shancwn & \\'Pb111t 111..:. \, ;1s ..:,1n1ra1.:kd h~ h1u:-th :\ \'r..'llltl! _.\:,;:-,;111:i .,tc:,;.. l. \ .( · t1, ,,,nthn.:t ;,\ \\'ctland ddlm:~11ir,ll l'I\ Kin~ C"t.)U1lt!· l;1-..: parl,,'.l'I no. ~l X.2 IOOO.:!O. ltmw.:rly ktwwn ;1-s lh1.• Rihcr;1 Hulk(1 Short Plat (hcn.::atkt n.:rcncd h' a:-. "thl" ~ilL" .. ). \~ ithin th .. · ( '1ty of H.i.::ut~111, \\";.i...,hington (('liL I .-·4 Si.:,('!it1n 15. l(1,,n:--hip ,2,\ ,. R.m~1.· 5 E;1!'il). ·1 h1.· 1H111~1'.'1.' nfth,: wdl,md 1.kli111..·,Hi\Hl was to pnn·iJL' ~, ~h..·1i:nnin~1tlo11 11f lh1.· cx1cnt. lim1b. ,ind ratc~11rii.:~ ti I' :-i Ii.:-wct lamb th al :,;ti 11 L'.\i~l on lh1.· pr~,p1.·rty. Thc wnrk ,,·a:,;. ;,mthon1...:d P~· ~Ir. Tom Fn'.sh:rp(r11l1rlh An.·nu1..· A.ss,H:i.:ik~. LL(' mid \\.I'.' pc.:rfonncd in ;,11.·1..·,,nlani.:1.· ,n1h our pn,pn:--;.11 dati:tl .luly 13. :one.. • Ri:\·kw k:..-kgn,t111d i11fon11ati(ltl a\ ailallh: for lhc :-;i11..-. in\.'luding 1hc City 11f R..-nton \\'1.·1lan<l rn,·('nlvry, King C1,un1y inh.-ra,.:1i,·1J m,1ppi11g systt.·m thUp: WW\\.Jll1.·tr1,ki.:.g1),. gi~ mapportal i.\tAP ... niain.htm) .. a11d th1.· King County Soil Surn.:-y. .. ld1.·ntit~· and r1.·ddirh.:ak \\ClL,11ds foun<l tir1 1.11~ :rnhj1.·d prnpt.·ny 1hat irn.:ct 1hc thrcc- par.imckr juri:--didi\1nal definition as (.'.'stahli:-.hc<l hy th1.• l 1.S, Arm) Corp~ ofEnginccr·s 19S7 \\'1.·tl:md:-Dcll1K'Jtion )\lanual <md lhl'.' \VnshiJ1gt(1n Stale Dcpartmi:nl of Ecology (En,'ogy) 1997 \\.ct\::md Idc-ntitka.[ion and Ddincmi\1n 1'-.·1,mual. • Prepare .:1 site :;k~tch showing the apptCIXimat~ extent of ·he i:dcntilicd wdlamls. 10 be us...:d by a surYC)'\lr to .sun·cy wetland flags and tlata p-1..1int lm:;;nions. • P;epan: n wetland 1.klincation rcpl,11 <lcs<.:rihing our methods and the resulls of our fic:d\\'ork. and categorizing the wethmds found on the subjc1.:l properly according to the old City of Renton 's Wc1lands Management Code. I.I S:te Location and Dcscnptlon Th~ subject property is locatcJ on NE 4th Stn.:ct. ~outheJsl ot' its intcr:-....:ction with Union A. venue NE, in Rcn1011. Washington (Figure I). The site is approximulcly 5.98 acres in size. !Vlaplewood Creek flows south along lh~ west border oft he site. and exits the silc 1hrnugh lhc middle of the southern border. The site is bour.,kd by NE -1 1h S1rect on the north. and by residential and 21-1-l2193-00] ' . ~ ': ', '. i. ' :" .. ... .... -, ·,,.1 . . .. .,, . • , .. ;J .,. '.Ji ·-l .. ·.I ,,. i'.1 !l!I ·,1 ,. ' ... , • i !-~ !II [ « • SHANNON &WILSON. INC . \.·\1m11w1\:u\ u,.._. pn1p{:rt11.:..., t,n tlw ... -.1,1. \\ l'"L ~md ... nuth The pnip,.:1 ly ..;puth t•f 1111.' "ih: h;L:s hl'l'll tilkd. (ri...·,11111.~ ~·.n .1ppn.•\1111.1ld) I '.'~t\it)l ri .... i...· ,!Inn~ lh1..· c.,~h:m h.111 tirrlw ..,·n11th pn1pc11y Hni.:. Gl."n-:l';llly ..... Jh.' h'p11gr,1ph~ :-h,p1..·~ di!\\ U fl.."lllfy h\\\ .ird !h1.: .. oulh\\"l'Sl :-ull· ,,r !ht: llltlpl.·rty. I li::;tt1rii:.1ll)'. p1.1rt1,,n:-,; ,,fih1..' pr~1 pn1~ h,l\ 1.· ht:1..·n \ . .'li...\H'l..'d .;1nd tilh:d. ,m~I r1..•n.·11tly a:-. part pf th~ pmp1 -"CLI pr,1p,.:rty u:--l· lhl· :,Jh: w.r ... 1.:k.1rcd and il :,;h1m1 r~•11d \\ ,1:,; 1n:-ti1llcd ,_lion!,: lhl~ -.(HJlflw~·~t,.:m pn1j't..'11y t..'dgl' ;tdJ,h.''l.'111 thi.: \\'dl.rn,l and .... trl'alll. Thi:-: pn1pi...·rty w~1_..;. <'tigrn;,lly tklineakd hy till' -.,11m.· l)inh.1µi-.l ,Ll Sh.1nrn1n & \\'Jl:,;1111. Inc. L·ight yc,1rs ;,ifP In lhc \\ mtcr 11f J<N:-< . ..\t th;11 t111w 1/w :-ii~ w.1:-hirgvr ,ind i,11.·lutlnl wh.it is miw 1'11.· :-,;itc: l1f1hc 1h..·,,· p(1~1 ~iflkc.·. (h·i...·r time w1...·tlanJ liou11dariL·:..: h:nll h1 l'h;1ngi: hl.·l·;1u~i...· nfaltcral11H1:- h' ,urwunding an.·~1:-. and hi...·c,1t1:-.1..· wcthmd~ an.· dy11,11mc !'>Y:-.'i...·rns. Thi:-rl'lkhn1..·a1wn w,:is climplctl·i.l b1..'l\1Usi: thi...· nld :-:111...· dclinc~1lil1J1 ,,;,~ doni.:-during .1, 1..Ty ht..•a,·y s1,m1, 1..·,·..:01. H:.ts1..•1I on n·c~nt :,;1h:, l"•(l:-.. ,,c bell"-', i...\.l th,11 th ... · :-.ill.' Wi...'lbm.b ,lt.:fl' tikt.'l~· difti.•r1..·nt lhan w!K·n th1..· 1\rigin.11 lklinc;1til111 w.a:-: t:1l111pk11,.,J . ?.II :\IETIIOllS Sh:llln\H1 & \\"ibt\11, lni...·. c11ndUl'li...'J the \\t.:ll:uH.l lh.'litlL'Jlillt\ ticldwtirk (Ill July ::::s anJ 16, :moo . \\\·tlamb \\\."r1...· ddmcalcli u:-ing nwtlw,J:,; dc.•:--.1..Tihi...·d in th~ I 9S7 :\rmy Cn1r1~ ol' Englm:l'r:i \\'t·ll.:md Dclincalillll ~lanual. :-:uppk111i...·nt1 .. •J hy thi...· t:...·l\l11gy l91J7 \\'i:tl,md Identification and Dchn·:atinn ~ hlnu1.1l. Site: i.:onditfon:,; w~ri...• ~,t,:-1..T\·cd Oy walking lhc: sih: to <lch:--nninl! whether it hnd hi.:-cn n.'t:i...'lllly cJi~tur~i...·d an1.f t{1 iJi.:-nti fy pl.anl i...·~)nrn1uni Ly typ.::,: anJ ,H·lla11ll da:-~ifii.:-,uion tn11.•s, \\'~tlJ1hl pri...·si:..·ni...·c: and bollnJ:uii...·s "i...·ri: lklim.·atc:d hy t.:l,nducling a wutini...· mdhod dt:lmcation . .-\ppi...•mfix .-\ indud1.·s .a (Pn,ph.~ti: <lcsi...·ription ofmc!hodolog.y used. Data plots \\'t:ri.:-1.:'h.araderilcd within i<k·ntificc.l wetJanU and upland plant community types to help describe-general conditions .11 the site. InfiJrmation on vi.:.·gd:.Hion. soils. :md hydrology was co\lcclt'"f.1 at c.Jch data pnint. Thesc data rlo1s were t0i...·atc-c.J nelJr the upland\,:etland interface to nwrc aceuratdy di.!tcnninc the-houndarics ofon~siti...· wctlm1J.s. lnft.imtation gathered ar these locations is provided in -~rpcndix B. \\"ethmd areas ,\-~n: der~rmined using 1he trip[c-paramctcr tlpproach. which considers vegetation types. soil conditions. and hydrolngic condihons. For an area lo be considered wclland, it must display each of the following: (a) dominant plunl species thut urc considered hy<lroph,1ic by the 21-1-12193-00J I ..._ 1 .. /; ,., ~ .I !'I .J i :"~ .,t /l '" .q !I SHANNON &WILSON. INC. 01L"1,,,·',;p!l.'.',l d,1s.~1fii..:i11l1111 indi....:arl~rs. fhl ~.l)lh !hat a,r (cJttsidu\_·,I hyUri1.: urnkr 1'1.:t.h:r;,\ 1.h.:li11iti1111, ;md {,.:} tntl1i.:;;tw11:-of Wl·tl,md l1ytfh,h1µy. in an.:onh11, .. :L' ,l·i1h r~d1..·r:1l ddinit1nn. Pll·:1:,,:1..• -"L'l' :\ppt'thli\ :\ ti.ir lllllfL' i111i,rm;tl1llll an.ti t:illl'g11ri1al1l}ll t1fhydrnphyt1r \t.:gdalinu. hydri,.: ~,,ih. ,uHI Wt.:"tl:u,l1 h~dn1!1Jg_,· . ldcnlili1..·d ~\1..·lltmd;,; w1,...·n.: tl<.·lir11.·~11L'd hy fb!,!ging. lh~ \\"1..'tl,111tl f'11undarii.•:,; ,\ilh p111k ··wctt.1nd hr-und;1ry"' tl•1}!.gi11g. Datil pt1in{ hH:<1t1l111:--,,1..·rl' liag!!c-d wiih wlliti: ,111d (1r;1r1g,,: pnll,.:a dot lfaggini;. J.O l>OCl'~lE'<T REYU:W Background infonnation pi.:11~1ini11g to the \Ydl.md :-itc \\'a:--.:nll\_·c11.:-d ~rnd rL'\"i('wed J(,r ;•-. us1.·ful11c:,.~. ·1·h.,::,;c inf1.rr111;1tion s,1urL·c~ i1Klmkd: >-t.: -~. Fi:-h ;ual \\ 'iltlli IC S,.:rYitr.:"c ;\Jalitinal \V l'li.mJ tnn:1HtH y !\I ap \)f Rcnlnn. \V:1shi111-:.ton Quadrangk. l :2..J..oon ~.:~lie (U.S. Dq,ar11111.:-nt 1.~fthc lnlainr. 19S8} . .,. L1.S. <..IL'(1h:1gfr:il SurH'.Y \lap .,,r Rl.:'tll<~n. \\"ashin£,tn11 Quadra11gh.:. l :24.0flO si:ak (U.S. GL·11lngi(al Survt•y, 1994 } . .,. U.S. s.,-,jl C(lll:-:.c..~r.·;1ti(111 Scn·i..::c (SC'S) Soil Surv'-·y .. 1fKing County J\n:.i. Washington·· Sheer No. 11 (l'.S. [)cpartrncnl of Agric·uliurc. 1979). • King (\,unty lntcral'ti,·c Mapping Sysrc1n ~ King County iM;.1p (hltp: ..-,,·,\·,,·.nh~trokc.glff ·gi~ ·inapport.:il iM:\P _ 111ai11.htrn ), .,. City t1f Renton Building. Rcguhuions. Chapter 32. \\\·tlands ;\fanagcment Cn<lc-{Code Puhlishing. Inc .. 1998). Nd1hcr lhc lLS. Fish an<l Wildlife Service l\'alional Wetland hwcnlory Map (Renton, \Vashington) nor the City of Renton \Vctland Jnventnry Map indic::it~J the prcs~~ncc of any ~vctlands on or near the site (figure 2}. M.iplc,,.:ood Cr~c!-: Jppcars on boi.:, maps, and is classified as Ri,·crinc, intennillcnt, strcambcd, seasonally lloodc<l (R4SBC) on the Nalional Wetlands Inventory \fop. The King C'ounly Soil Survey (Soil C'onscrvalion Scr\'ice. 1979) (Figure J) maps !he site as conl~ining Alderv,ood gravelly sandy loam, Ag('. with b to 15 pcrcenl sk>pcs. This series is considered modcra1ely ,\'ell drained. with a weak 10 slrongly consol:dated subslraturn within approximately 24 10 40 inches below 1he surface. Runoff is slow to n1cdium, and the erosion ) :-i hazard is moderate. This soil lypc is considered non-hydric on 1he Washin6'1on Stale list of • 21·1-12193-001 3 ,. , J • { ~ ' " Ill ' ,1 ta! : :t r:. ·,:.~ e.11 ,, >Yo '·•j ·'< I 1-l •! :~ '·~ ~.f q! :" .1;) .. , ,-·i l>,f ••• r.t :~ ti ,··~ ~ ;,.~ llil " 1 iii SHANNON ~WILSON. INC. h:·tlrh.· :-.11ib. llP\\\.'\l.'t, ,1., rnih:h .b tlu1,,·1.' p\·r,;1..·1u 1,!"1lu .. • .it,,_.;,_..; nt.1pp1,:d .t, ·\ldcn\11 nd t!raH.:-lly ... andy ln:lm, (1 !11 I) prrn'Hl. h,1\,; llh.:lu ... h1n.-. oi"llh· pi,nrl~· dr,Hntd \h1m1.1. Hdlinsh,1111. Sl'.!ltl1.:. Tuk\,:ila .. md Shak:111 .:-t,ib f11i,.'-.l' '-Pil 1n1.:h1:-.111ns .m.: .1111..:t1U~uh.·r,·,i hydri1.: ~l,il. ~.II \\LTL.\:\ll ..\IU:,\S A:'.IJ STRL\M Two \\l."ll,llld" 1\\",.:tlan&-. .,\ ,IIHI B) ,1,.·cu· uk·1111ti\.·1.I {lfl lhL pr1ip1·rly frigl.m .. · 4) Hoth atl' ,1s:-nt·1~1ll'd with \ i.1ph .. ·wpod Cr~1,.:k. wh~ch lhn-.. :--,1h ~ni; ltl~~ \h'.,krn ;ind ..,,,ul ht..Tll b, 1\u1tl,1ry 11 f th(.· prop-crty. \\"cd,ind h1und.mcs W\.'tl' primanly \.·~t.1hl1:--ltld h;1s,:1I \Ill 1l11.• H.'gL"t,1ri\1t1 and top,,gr;1phic 1..·h,ingc:,; a:-\\ l;'ll ,ts 1h .... • pn.· .... 1,.·1h'L' of .-;.1;111ding w ah.T ;111d hydrk :,;nil 111dk,1tors, \Vl11 I·: dala were rtn,hkd fnm1 nilk' lbr.i pl\11:-.: !l,m 11phrnd plt•1:-. ,md f'i\'C w1..1land pf Pl:-. :-.c, tr,111itl11.:r s1,il pil:s anti sil1..·:s w1..•r1,,,• l.:''<~11nin,,..d h, c.::-.1;1hti::-h th1..· \\'L'llaiul lwund:1ric.~. l1.1ta :--hc..:1:-tll'L' llh,;hulc .. .-d in :\pp..:ndi, B. 13;1:-...:d (lU t 'S-F\\'S ( '/antfi(·1rrirn1 or H ·c,lcmd, /11 I k(Jl\\ 1Jlff I (idl/!ctls of the l -·1Jih·d SWl<'S I I<}')]) hl1lh 'l\ l.'tbL!-ds ;ir .... · p:1f us1ri11"-". s1,,,•ruh~:-.l1nih f I'S~) wdl~1 nd ..:11mmum1h:~. -I. I Welland ..\ \V..:11.an"I :\ {.1U.6l ~ .squan: fL'l'l) i:-; ll,\."i.lh:d i\h111g the\, i.:~h.:111 pn1pcny h~lUIHhiry ,111~1 i:-; u:-:,;\ll..'1a11..·1.I wilh .\1.Jpk·wl111d ('red\.. Th .. • \'-1..'!iand is ,·..:g1..·1ntcd with a lhil..·lo,. :,,;1,:rul,-:shruh ;,,;tr..1tum LlVCT ..in h1..·rhacc1;.,us ~ra:i-s umkr:-tnry. l{ecJ t:an~irygr;1~:,; (l•!i,rl(,ri.\ crr111r1li1111t·,·a) ,in~I h(:tH gras~ (.·Igmstts :--pp,} dl1min:1k' thl' herhal'l'OU:-:,;tratum. Patch\.·~ 11!'h:1rd h;1r.:k (Sf,irnca doug/aJii), rL'd osi\.·r dngwnrn) {<. 'or11w.: .\tolonlfi:l'a). willow (Salix s11p.). ni1K·hark rl'/1.1·.rnccnpus cc1pirarus) anJ r\.•d :.1IJ0r (:Urn,.,. r11brt1J. which t::\)lll)lri~~· the :-i..·ruh ~hruh :,;tratun1. an.: h1.·;,1,·ify CL1nc1,.·111ratv(.l lnun1.~iutdy atlja~i:nt lo the ::,:i.n;am. The pl:J.nt indicuhH st;:itus ten pl.:1111 species fi.1unLI within this wclland rnngcd l'rnm FAC h1 F,\C\\'. which lflL'Ct~ the t.:rilcri~,n for hydrophytk VC"gcrntion . Soils \\.'C"rc anal_v-1.cd for color. tcxtun:. cmd nwi:;;lurc t.:ontenl. In gcncr,d. the snils observed in and adjacent t<> Wetland A 11·cre sandy 1,,am, grawlly sandy loam, and pockets of till. Wetland plots contained low-chroma s~ils. Soil colors within the wetland data plot, varied, although all satisfied hydric soil criteria. Soil colors II ithin plots .1 and 7 were comprised of very dark b'TllY ( I OYR 31 l) 0 to 16 inches: black ( I OYR 211) 0-7 inches. with very dark gray (IOYR 311) 7 to J-1 inches in data plot 2: and black (7.5YR 2.5.'I) 0 to 8 inchci·, with very dark gray (7.5YR 311) 8 to 16 inches in data plot 9. Saturation was nut present within 12 inches of lhc surface at the time of the field visit: 1,owcver. the field ,·isil was conducted during the dry season and soils would not be c,..;pcc1ed to he nioist. This is i:spc.cially true bc('ausc Mapiewood Creek. which 21-1-12193-001 4 _,,. '" .,. •'1.! ·-~-•• ;; . ...i. .I 1,; ,l lc!f ,,,I ... .,,\ l'll ·ll bi ·1 Iii ,-.l ', !JI ,.i ill ·~ Iii 11 ilii ·~ LJ • SHANNON t..WlLSON. INC. 1111\\:,... Jhn'll!-!h \\ ,:1.L1ritl \_ \\,1, ,1\:-n' dry ;11th,.: llnh: Pt lht· lldtl , 1,11 I l1rn-l'' L'f. llydrtiln_l!~· 111d1(,ll\'P, Ht'r1..• t:Yhk111 in rl;1u_·, m lhL· ,\i..:tl.tn,l ,ud1 ,i..; ,,.ikr lillL''· :-.L·dtn111...·nt (h:pt)s11., and 1lr.1i11.:1g .... p;1\h.'f"\l),. nlU':'. \\T(LhHI h~llr,1111~~· ..:h:1r.1d~ti.,1i,,.-:, "l'H.' ,lSSlllll•,:d hl ri...·r~1sr h1r ;J ,11flk11.:111 di.U-,lltllll !o S,lh'il°y !hi.: 11ytln1 ltlJ!l1.: 1,:nil.'ntli'l \\'.:[I.ind l1,1lltl\hrrn.:, \\'l'h.' wi111;1nl; \.·,t~1hl1sh ... ·,l l.ia . ...:1.·,! ,,n 1lh· l(,i111~1.1plu..: and, tg,:lalin: ,.:h,mi_;\· ,:nd !ht· rn..::-:1.·111:L' 1,fh~·drir soils. \lu1..·h 1lr th1, \\'1.::Lu1d 11:is !11.:1.·n di~turb~d in tlil· r1~1,t .i:-n ldi:1h:i:d by d1h:hing \,f i:r1.:\.:k. old fill pile,. and ,,-...•ll,111-d pl;,11111.:,,1nmu11,11..::• 1rhhlali\'o1.: ,1f tltslllrhl·d ,,:,111di1i.,,1:,:, ..:ud1 :1:,, n.:i.:d i:.1rl.1rygr::1:..s ,Uhl hJ;1d,b1..'fl'y. ~.2 Wctl:uul II \\'(.'ll;m~I H ( l. :.,s :-lp.1;Hi: li..·i.:-1} 1:-=. thid:ly n .. ·~dah.·d. with ;1 dl'll:-,l" :-s..:ruh-'.".hruh u11di:r~h1l :,·. :\spl'll (/ 'orul ux n ·c11mloidt' ~ 'l. \\ i 11 l n\· I So h\ .,pp. ) . :,;it\l w berry f S1 .,,,, .•horu ·011 '"·' al bm ). :rnd Pad lit: '\;iu"~harJ.. U'liy.$i, ,H'fHD· c<1;i1Mtu.$ 1.h1min;1ll' !f1l· s,:ruh ,hrnh •;1rarurn. The h~·,h;u..·1..·11u:-slralt1111 is l·nmr~1:·l\l 111' :-.h1ugh .,1..·dµi: (Can.:.\ obm,rraJ l li111,1l,1y,111 H.1d;,hl:rry ( /(1,/111s di.'icoh,r) Lh1mln;1ks 1h1..' d1:,;1urlwJ "1..•tl,111d '-'l,!,;."' wb1..·1T~1.: the lHh.li:,;.lurh1..·d wi..:tland ctlg1..· wa:-. dl.!il·ncd hy ,1 distinct \ q;etalion Iran~ili~lll, l"wm lhl' nfnr1..'llh.'ll(io1H;d \\ L"llalld Sl'l'llh-;..:hrub pl llll.'i 10 ;J dt.'.rlS\.' .;O\'L'f or ~:11:ll ( ( ,'4m/fh1'1 ;,, sl1c1f h111) and ( lrcp,n-gntpc (ll~·rho.,_1; 11c1Tos1,). Altlinugh th1,.• phw' indkah.lT sti\tll:-. f\w plant ;o.;plYii.:~ f\rnnd within \\"ctl~nul B r;mgnl fmm F:\Cl.i to (lOL till' 1nc~~,minant \'l'!!d~1lt\·i.: l..'.l1t11t11Unil) H"a:,. OBL IP f.-\C-t. Dt.imiuanl pl.mt ~pc1,.·ks in \\"l'll~1n<1 0 met:! thr 1,.·tit~ria for hydr,,ph~1ic \·L·gd.:1thm . S(,ils \\'('fl' an,11;~1.l.!d fnr colnr. tc~tun.'. and nwistun.: \.'.llllh.,nl. Tli1..• s,,il:;,; ~,hslncJ within th~ wi.:tland WL'H.' sandy h,:.im. wi1h rwi:kct:'i nf grJ,·d 11r !ill and ,)rgunics. Seil L'Oll1r wilhin data plot ~ "·as black ( I OYR ~. I JO Iv 13 indws. and ,wy dark hn,wn ! 7 .5\' R 1S1) IJ to 16+ inc bes, H"hich satisfies the hydric ~o-il ,:rilcrion. AltlH.mgh SC'lils \,·ithin \Vctlrmd B were not :.-aturiltl..'U at the time of the .icld visit. a berm along the western ::m<l S\"lUtlJcm t.xlgl.' of the wetland ctTt!ctivcly cul off th!.! hydrolog.ic connection to t!1e stream while impounding. surface water and prccipitution in the wetland. Based on these field conditions, the wc,laud hydrology charactc'fistics were a$sumcd to persist for !-ufficicnt duration to satisfy the hydrologir.: crill~rion. However~ it is our opinion that due to the recent on-silc clcariug and piling vf debris. the Jcvclopment of the Postal Service site. and ihc ongoing development to the r.!DSt. the degree of surface \\'atcr thJ.t m.:1y h.:1vc rcac.hed this \YCllilnd in the .:ast likely no hmg.:r can gel to the ,,,:ctland. 21-1-12193-001 5 J . ~ I ~ .,3 ~ re r! II :.iJ !I ,ij ..-::· it j.J ·; ... z• ._,. nl ~l \ii ··, ~ ll 1\1 ., ii t/ if i .:1 j . ' :~j I ;..) '.I ii '·"· SHANNON & WILSON. INC. ~ .. l l plant!, n11.· \ \.'~t.'l;Jth'll 11f llh.' ;H!i~IC\'111 lll'l.1nd hul"h:r J.·. \.·oinpn,,l.!d t•r 111111,d,1 y,111 hl~11.;~\ll'l"f ~ { Nu/111.,· r/H.('n/{,r_L tl..'l.'d t.',111,H, ::r.,,:,.fl'il,:l.111, 1r> ;u;,/m1w,·ll I. Sro1 ·, l,r,1<1rn ( l \tu11.,· _,, ·11,:,11 in.:). ( \111,ula 1hl~1lc (( "init1111 (1>'11'/1\;.'J. awl ,n,mh,:rr~ (.'fruqiliorici1r;i11\ a!f11n·). a . ..: \\1..•11 ,1., m;m~· ,:ancth::-11!' pa:,;tun: !.~r,1:-.:-.. l'IK ... , 11 h \\ ... ·rl," ... ·,1r11pne...:1,;d , ,f ,!!r,1, ,..'lly :,;;md y I, 1.1111 and ,·ny gr-i, l'II \ sanlly loam. and w1.·t ... • not :-.almah .. 'll. Thi.:-:~111.· was d,:ared a111i f,n1hh ... ·d t,._, ~\\ti' as p:1rt \)fllh.· pwpo.s• .. ·cl :,;lwrl pl.at. A :-lnrm pnthl ,, .1~ rn:-.t,111...:·d hul i:,; 1111t y1.;t 11pcr;1t1,,n11l. rn 1h,__· :-u11lli w ... ·:,;t 1wttH1n L•f thc si!,.:. ,1d_t:1 .. ·1.·11110 .rnil h1..·1wc.:-n1 \\'c1l,1wl,; .·\ ,in~I fl. Port inn:-; ~1f 1h1.: hufkr aro1111<I \\\·tland B l1t1\·c hi:1:n dc;.1rt'lL and ;1 largL· gruh pik ,,:1.--pLK1..'l.l !1) lh\· nnrth nl'lli,.; \H.·1bntl . .-\t lh...: r·equcsl nl"lhL' Kin!: ( \i1111t~ :,,.;(, x iou:-. \\" 1.·cli h\ ,ant. 1hc upl~md p\,nh.H1 nr the :-.it1.' \\ ;h r1..·i..:~·,11i~ :,;pn1~-... -d with a11 hi.:-rhkid1..· to 1.'r;ulii:.1tc sulfL·r citHJu,.·Ji.1iJ (ro1n11i//11 ,.,.Od). ·11w ilnbii.:i,k :1rplk;1t11r:,; did 1101 spray th1.; wclli11hl :,.tn.·,un hulfrr:-. ~A Stream ;\fapk,\\1~,d CrL'l'k Ihm~ i11 ;1 :-ou1h ... ·rly dir1..·dion tllrnui;.h tli1..· w1,.'\l ::-iJc ~·r !he propwly, :1ltimu,g.h it w;is drydurint! llll' July t!l'ld ,·is1t. The western cr ... ·ck han~ :•dupe:,; up \·.:ry :-:h.::crly. while 1hc c;1::.l"'m hank gcnt.•r;llty ~toi)c.:,; mnr1.· gr~1JuJJly_ The a1..·1..'i.. cntL'r:-the nurtlnn.•sl !'li<.k of the pmpcny 1hwug.h a larg~. 4-tl,l,t-(li;.Hn~tt.'r ...:ulvtr1 under ~E -4 111 Slrccl. A st·,.·ond !'>malh.::r 1,;ulvcrt 1:ntcn.: the sit~ ,1h,ng the nl,rth sid ... · of the proncny and prn,·11.ks st,mc minor nttditinnal flow to llt1..· cn .. ·ck. Thi::. cuh·cr1 w~1:-nwditicJ slightly las\ yc,ir when !ht..· sftc wa.s dcarcd and grubbed. The stream n.ughly tlows p;:u:.illd h1 the Wl'1'>ll·m lw.-1'd..:r 1.1f th..:: property until it npprouchcs the ~1,1uthcm propcny hl,untlary wht.:"rc it nhruptly drn11gcs to =in eastern direction and exits the site tr) the south halfway al1.mg the s1.1ulhcm propcrty liordcr. The channel wa!'> ditched Jlong most of (he 011-:..ite rca.1ch ,:it S\1ll1C time 111 the pasl. Maplewood Creek enters the Cedar River after po~sing through the Maplewood Golf & Country Club. and passing under State Route 169. Our study dj,J not include an investigation of fish use of the stream. Hcl\,-i.::vcr. a rc\·icw of cx1sting infonnation and our field verification indicate the stream is ephemeral. going Jr)' during the summer. Additionally. the creek is reported to have fish migralion harriers downstream of the project area. Thus, anadromous salmonids arc not likely to be present in this section of the stream. .;1.1.J~\•H.OOI-Hl d,,~ ""PI ).I) 21-I~ 12J93.001 6 ,, 'i , " :: .. . J " I 1. ., ... ·• ,,, SHANNON & WILSON. INC . ,.11 \\FTL\:s;() ,\:,,;t) STHLnl nn;n.,\TlONS Tlu.• Rilwr;l Balho Shon plJ1 \Cl!-appr\,\ t.:d 111 Jun._· ;:!Hn~. ,md i, th\.·ri:1(1n: 'T"'ll:<t umkr illl' Cify t,i Hl'nll,n \\\:ti.and \1;magrml·nt Ct)th.· llflhL" Builthng lkgt1lati11n ( 'ode.· ( 1 t)9:,()_ ,\s a n::,;ull. the 1~~'.1,1win!:,! i:11tk n:\·i1..·w w.is ...:nmplclt•d u:'iing tha! uitk. ;\ co111pn.:ht·t1sin:-ru!111~ :,;)'!,1Cm fnr ,, i..:1!;1rnl:,: i:-i.::on1.1it1cd in 1hc ...:<1th.· ,,·a., u:-.cd t,1 rall~ 1.:at..:h wclhmd l\1 tlt..:frnninl." th~ sla11d:1rd bulfrr SL·th~1.:k n.:qutrcd. Rc-i1um.::d huflt.·rs srn1ou11J lhc.: deli11cah .. ·d ,,·c1larnb. and -~hnuld not he i11ipach.·1I h~ dc.n.'hlpllh:11t unh.·~, mitig;1ti1H1 for in1pw.:I:-; is prn,·idi.:d. S.I Wctlnnd l!alin~ and fluff en \\'ctl.rnd ,\ ,ni:. i..~h.1s;'ilk·d ~1s ~1 Cati..:gory J ,,'l.:tlanJ hL"..::aust: i( i!'i gn::iti.:r than 5.000 :-;quar1..· lt..·ct and has hci;n di~turb,,:d lhrmigl1pa:-11..hti.:hing. filling. ~rnd <.·k·:1ri11g ofn .. •g1.;talion. \V1..•t(and A was da:,;.:-:ilicd .is a f'attgnry 1 ,,'l.:!l;ltld b1..'l.'at1s1..· ii i:--less tlwn :i.000 ~quan: fc('t and it dnl'.s 1w1 tllCL't any of the l·rilcrL.1 li~Ll·J foi-C;,1112,gpry l l1r ~ wc1lantb. Calcgory .~ wetlands, as lis.ll.xl in the Rcn1t111 \\'c.:t!:11H.b ~1:inag1..'llll.'1JI rt•guhttion.s. n:quirl' 2:=;~rn\11 buffrr:,,:_ I h)Wl'\-cr, urnkr the Cily of fh·ntnn·s W1:1hm<l~ Mana.gcmcnt rcg\il,ninn:,;, C'~Hcgl~ry J \\Clland:'i .surallcr than ).000 s<iuarc frtl an.• l..'.lmsidcn. .. 1.l 1.::xcmpt. Thcrd't1rc. only \\"ctbnd .-\ would h,.: rl..'quin:d hy the dty 1tl maintain a ~5-font buff1:r. 5.2 Stream Buffen "'" Str('ums an.: r1..•gul::ucd within tht• Cily of Renton Building Rcgul!ition~ ·md rcquin: 25-foot huffl':rs ~• '. - ... ,j •• 'I .. ,·Jl ' • ~ w from the edge -of ordinary hi.gh water. Ordinary high water ln ·his stream would likely be considered the t."Cigc of the ditched bank. Land cknring or lrc-c cutting is not pcnnittcd by the City of Renton \\"jThin stream buflcrs. Because th1..· ~tn:am i.s contained within the wctlnnd, the wetland buffer would ex lend beyond rhc slrcam hurter and govern the cxter.l of development on tl,e site . 6.0 CLOSURE The findings and conclusions documented in this rcpo11 have been prepared for specific application to this project and have been developed in a manner consistent with that level of care and ~kill nonnally exercised by members of the environmental ~ciencc profession currently pr:,4.:tjcing und~r similar conditions in the area, and in ar:cordancc with the tcnns and conditions set-forth in our agreement. The conclusion an<l rccomnicndations presented in this report are 21-l-12193-001 7 J . -~ r .. ! IA j "' ··' '*" I "' ·' ., ., ,, l la SHANNON ~WILSON. INC. prol'css1nnal \lpinion~ ha:-.l'tl 1)1\ ink'.rprl'l:Hion of infom,ation l'Hrn:11tly ;n,:ailahk ln us. and an.' m,Hk wHhtn thl' ~1pcr,1tton,d sCHl't'. hudgt'l. and ... ch~dulr rn11strainl:, nl lhi." projct:f. No warr..1111y. r_,prt·~s nr implkd. j:,, matk. \Vctland huund~lric!-. itlcntifil•tl fly Shannon & \Vi Ison arc \:\lll~idcrcd to he prdimiliary until the Corps atH.linr the local juri!-dktlonai ~1gcw.:y v;1Iida1c the th,g.g_l·tl v·dland ht•undarics. V;didalinn of the wctl;nul t,ound,1ry hy tht: regulating agcncy{s) Jlf\1\·itlt.'s a C!.'nili1..·:1hor,, usually writlcn. th:lt tl111..• wctlJncl hourn.lari1..•s ,·crif:cd ;irr-lhc houndaric~ that will hl" r1..·gulat4..•d hy the :1gi:ncy{~) until a :,;pcciftcd dala ()r until the regulations ;ir~ m1nJiticd. Only the r..:gul:1t1n,g agcm:y(s) can [lrovit!c thi~ certification. Sim.:c wetland:-. ~re dyn;.1111ic communities affcclcd Oy hoth n~tllr;,I and lrnman .iclivitics, chm1ge,-.: in wetland bountlnrics may he c.\pcc1t•d: lhcrcfnrt<. wetland dclincalit1ns ca11t1ul rcm:.i!n valid for an indefinite period oftimc. The U.S. Anny Corps ofEngi1wcrs typit:ally n:cognizc1-the v11liUity of wdlnnd di.:linc~11iu11s for a period of tivc years alkr ..:ompktion a11d tlic C'ily of Rcnhm for only two years. Di.:,·d(lpl\lt.'llt ;ll:livi1ics (Hl a site l\\"O y~11rs ,1tkr the compktion (1fthis wctlnnd ddincati(ln rcpon may require rcYision of the wdl:.rnd ddin.1.:ation. In 1Hldition. char..gcs in govcmmcnl cot..k. rcgulati1.111s. l'r laws muy occur. Bci.::ausc oh:uch ch,rngcs bcyo 1,1d our control, our observations ,mU corn:losic..m:,; regarding thi:-. -site may riced l{l h1..• rcvi:,.cd wholl~, or in prirt. SIi ANNON,'< WILSON. 1:-,;c. ~t.w,.t~- Katie L. Walter. P.W.S. Associate Natural Resource Manger KL W:BSK:DNC/pcj 21·1·121'11J.(l(H-kl ooc.,.·pU.::O 21-1-12193-001 8 i L f :- : ---'. . . , '.' .. ' ' i_ ,. ', I • '· ' , ~ .. . f ~, ·~ ~ .~ • "" ·1 ·~ -~ :~ ;,~ ·., • . ' cc • ;,t 1J ·t ~ -?i ,·-···. SHANNON &WILSON. INC. 7.0 IU:FflU'.M'ES t-!t:,. \·,f R4..'nll,n. I l)tJ~. C '1ly ,1t" tll'Ht11n Jhn!\ling Rcgttlalil,ns: ( ·od..: 11uhli_..,!,ing, lrh.' .. ~l·~iule, \\'ash (_ \1w;trd in. 1 .. \.1., and 1ithcr:-., 1979. ( ·1as..;ilic;11i,H1..., 11f \\'t..'th,ml:,. .ind drt:p\\· 1ltlT it1hi tats (l r the l )nlted St;ill':< l-:.~-Fish and \\'1ldlili..' StT\"it'L' Puhlii.:o.1tioll F\\"S Cl:SH-79, 11. Klng. ( ·oun1y Intcr<H .. '!l\·~ !\tipping Sy:sll'lll -King (\1u111y i~lap. h,11nd Pn thi.: \\\1rld \Vidl~ \Vd1 at: hop:. W\\W.mr,rnk~.g.t1Y gi:-!mappor1aViJ\lt\P n1;1in.!Hm l i.S. ,.\nny Corp~ of Engint..:cr:-, I i);!.7, ( \1rp:. of h1g:ineers \~ l'tiand..; ,kli11catinn 111auual: ViL·bhurg. i\tiss .. l!.S . .-\rmy l:11girll'LT Wa11.•n\·,1y;-; i~.\pcrimi:nt St.ition. Tcdmil:nl R1...·pnt't Y-~7-1. l r. S. Jkpartmenl (1 I" AgriculturL'. Soll C{ima:rY;LI in11 S~r\'ii.:c.:, I l)7t>. Sni I ~~Jr\""-'Y (l I" King Cuunf y. \V~1shi11ghHt. l_i.S. l)cpart111cn1 (,ftht:' lntL·riur. Fi:-.h and \Vihllil~· SlT\"ic.:-l". l()S:,.:, Na1i,_1n:il \\"t:lland im·t:'nfl1ry map: RlT ,nn. \VashingtP(L Quadrangk. 19}:S, 199J, N:.lfionill \i:-;t nl'plan: -"PL'cic~ that tlLTut in \\"l'llamb: Norlh\\"l'Sl (lh:giun 9>. Biological Repon ~~ (~6.9). U.S. GL·t1lngi('a) Surn=y. 199-L US< iS h1pogrnphic map: lfr11t1.)11. \\'a . .;hingltm, QiJa<lranglc. \\.'ashingllin State Department or EL"olog.y, 1997, \Vashing.ton Stale wctli.mds idcntifieation and ddincaliun m.;mual: Publk:.ilion ,:96-1)4. \Va:-.hington ·st:.itc Department of Eeoloi;y. Oly111pia. Wash . 21,1-1~)'1,l~IOI-Rl.d..x: "11 urn 21-1-12193-001 9 i'. ~-': ' r<--.... : 1: -----·------L._ ·----------------·~·-cw•....,·--·- :-io11lhc•,1.-;l t:!0111 :--:(n•f'I (h:111µ f'o) N(Jl"lh1-,1s! -llh ::iti·i·r,l (f?<•nlo11) -~., .,, ' ... . -· -' ,, ~ ... ·"~ ,.<,:::-:.·· ~ ·-~" ~.:,_,•' ~ • ,"I ,I•,• • ... ,f-_;,. ..,;·~·. 1 ' -!',.,• -... ...... _.,. \ ' .. , .. , .. · . -~"' ' · • A,pro:11m.-, Loa,u11n or ••P1wood t:rMk '.JI 1·,·, I I, ,I' .... .. ...... .... ,...-· r ,-. '',..,•I ......... ... ,,,,, .,· .. ' ~ ~··· ,' .. '. ',• ... ~ ~ .. - ',' ,· ~ .... -.. ;.·t :,t· ' , ... ~, . .,,.o: . . ,_ ' -... ,.;, .. '· "l~ ' ... ·.;:,\ ~ ' ,. I ,,- Welland A (M,1512 Squ,rt Fett) 2.!i-FL Suffar , ' I i ... ~ ' ...... ,· ,· -' \ ;,· ... ,,._ ~ ....... "'· . • Wetland& ~... / ~~ .. , ! .. ~ , ,, . K'; 1 (1,731S SQu:.No he() •' ~ ' ~, ~, ... "l' ~~-·· _ ~,< .. • 1-::.·:":" /. t" • • ,· r " .... ,_..,: 1· . '•) ~-~ '/_.-;;; .... :~;2:·<1 '-:_ J .: ... ,"-. =~- . --------., , .... , .. -... ,..,.._.. -""':~:-:.-~··-.... ~. -~ .. ~"~~-~w-.:.:·;ii;,,~·";,:,..#sMet.,.:·: 0 ' N I BO 160 ·-·· Scale ln Fe&! NOTE Figure adapted from e/8'cilonlc fiie. "'WetlaMs REvised B-23---06.ttwg\ i:irovlded by ci1enl on 6-25-06. 4th Avenue Associ.iJles Renton, Washington ;------- WETlANO DELINEATION MAP September 2006 21-1-12193-001 SHANNON & WILSON, INC.1 ~ ... ~~ FIG.4 ~ -~ i -i~ )~ ,., ·, :::, ,• ' ,:,; ,t. •r "'· :.r-t I ill ~ . ..,; ' SHANNON & \,\/!LSON. INC. "111 .I ... ,; •.'If • ··~ • . ·~ .,~ ., ' ·. ' \\Tl'! .. \:\ll DELI:\ E.\TIO:\ ,n:n !ODOl.O(;\' -~ ... .. '~ .. 21-1-12193-001 .. '.' ! -~ ; - .. - ... ... -{ • j !l ' ,.~·---';·'. -·~ ·: " .. :,' SHANNON ti WIL50N. INC. \\ETI..\\O IH-:LI'\!·'..\ 110:\ \It: nronot.o(;Y r ,m .E or co:-.n:'iTs .·\. l \\U I .-\\I) \Tl a··t .\ 1 l<Y\. A.2 I IYDRll" :'>011.S .... .-\ .. 1 \\TTl...\:S:D l!YDROI .O(iY I 1ST OF TAUi.ES Tahlc \o. .·\-l .-\-2 lkfinitlnns ,,[' Pla111 Indi~J.lor St;itus liydric s\,il lndi1.:.ll(lf"S .... A-, Pn}!e .... A-I . ........... A·~ ········•·""""r\~3 ; . ~-.. · . . . ........ ., ....................... ,\-2 . ............................. .-\-.1 2J-1-l2J93-00I "II ' •.J ' "" . 1 ; ...... ... .. ., .. . , Jot • '~ j l!I ;,f ht ;I If SHANNON bWlLSON. INC. \l'Pt-:,nrx .\ WET! .. \:\ ll OU. I \I•:.\ TIO\ ,u-:r11ono1.o( ;y Th..: tnpk·-par;1mdl'l' .q~pn\,t,:h. w, r...·\,uin.·d 111 th1..· ··( 'orp." t,I' 1-T1!;!11n:rs \Vdhrnd D1.:l1111..":.1!h1ll \l~tnuJI" (\t1r1..'h \\JS-) ;md 1hl' "'\\".1:--hin1;hH~ S1;1k \\'c1\;1mb lth,:111,tJ,.:atioH ;1t:d l>rlinc,111011 \ 1,mual" ( \ 1,m.:h 1,)q 7}. ,, a~ 11:--"'" t,) id1...•n! 1 r'y ;md dd i 1u .. '.11!...' thL' ,, ..:i 1,uhb: Pll th~ ,ih: d,,:~nihcc..1 111 thi:; n:pr,n. l '.nd1...•r 1!11., nwllwd(lh,~,-, n.·gr1,1t1cn. soil':-i, ,llld h~·dt\lhl!_!:' arc 1...·.1..:h i...·,·,1luar....:d h.l dd1..•m1111l· lh1..· pn.:scl$1..' ,,r ;1h,1.:n .. :t:" of ,,·1..,1l.111d,. ll.1~1.:d 011 llh' 11.,1.' t1f this mctht)d, ,111 ;m .. \l i,.., o,n~jtJc..•1\.'d 111 b1..• ,1 \\1 . .'lland 1fL',l1..·li tiftlh.' f1~fltn,ing i-; ah.:t: (J) dt11HH1;lflt hydn1ph)'t1..: \"Cgcl,Hi111l i:--pr..::-.~'lll in th\.'.' ,m..'J.. (h} tliL· _,1.1d:-. tn lh\! ,1r..:a ;1n.: h)dric.:, a1hl l.:) thl' 11c\.·1.:.:,.:-.ar~ hydn1h1gt~: L'i1mfihnn~ ,, nhin th~· ;m.·:1 <U"L' ml'l . . -\ dl..'lLTmmaliun pf,,l'!Lmd 1ir1..':-~·1h:1.: ,~·.1:-nud1.: h~· 1.:1)11dudi11g ~1 RPuli111..' Di..•linl.'.ali1111, _,;l1h:I.'. th1..· area ,, ,is h.•.-:_-: (h~m ~ ~Kri...•, ( E,~1~h)~~-. ! c){); ). ( $rr1..·:-;1h•1h.h ng. tirl.m,I :u1d '.Vt.:d;1nd plol!'-"nt: r1..·,·,1r\kd w llll'rL' a(cur~lld~ dl.'.t1..·nni1h.' th1..' h\,und.uics pf \lll-~il\.' \\\.'ll~11Hb . .-\.I WETL\;\O \TGET.\TIO;\ Hydwphy1ic ptml-' ar1..' pLmt :--p1..•dcs :-:11\:1..·1;11ly a~bph:d fpr :-:;]turJl\.·J ;md ur o.1n~u.:whic i..: ... 1nditi<1ns. Th\.·~..: spcl..'.1..:~ 1..·an he-t~)und in ~H1..'Js ... ,·h.:ri: 1h~r1..· 1., a sl!;!llilir~ml dur;.ition and frequency ,if inunJatitm. ,\·hid, pwdu1..·..:~ ,,, . .-nn;rn\.'.'ntly l'T p,·n,,dirally :-.~tunit1..·<l soil-;. I l~·drl,ph)1i\.· species, Jui: to J1h'rpth,lc1g.kaI. phy:-il,logi1..·;1I. and T\.'fll"~)Ju1..·fivc ad11p1:itit\/1~. han: the ::ibi\ity to gn)\v. cffccti\·t.~ly cnmp\?le. rcrr~ldth.:i:, and thri\e in ~m:.lt...'rohk soil. Thi: L.S .. .\nny Corps nf En,g.inecrs i Corps) anJ ,he U.S. Fi;h ,111d \\'ilJli le ScrYicc ( t:SF\liS) h:iw assigned inJ,rn1or ~talus to muny plant :,,,pci..:it:s.. basc<l on chc cstimJtcd prohahili1y of the :-:.pecic~ l'X1~ting under wetland ,·<mditi,>ns. PlanlS arc calcg,,ri~c<l as Ooiigatc IOBLJ. Facultarh·c Wetland (FACW). Facuhative (FAC'). Facultatin, t.:pland I FAC'LJ, ,md L'pland ( L'P L). Species with an indicator status of OBL, FACW. or f,\C arc con,idcrcJ 10 he :,dapli\'c to saturatcJ andior anaerobic !i.e .. wetland) ccmditi,,ns anJ .ir.· referred lo as hy<lrc,phytic ,·cgctatwn (Tahle ;\-I) . 21-1-1219]-001 A·l l ·····,', .,, . • ,J .. • ... • I . , ·-~ ·, ... ""' ,· i lllll !lil !-·~ if SHANNON &WILSON. INC . l\UI !·: .\-1 111:1, l'l;tl 10"" Ot l'l. \ 'i ! l'illlC \I OH ST .\I I''.', l;;:;-;;;~a~or ;~~~;;=<;;~~~~~-~~~~~~ --,-=~~~-. ~-~ T-~-~-~~ -..-.-.---.- ~ -~-,T~~ " • ...,..__..,,.._.,.~--·' ( l!-11[ Ill'\\ t 1t rn,l Pl 1111, itlKI l I'? i;~t-.. 1h.11 ,,\, 11; ,n \\1 :t.,rhl ... l>l1tf, T 11 ,l,H 11, 1•nd1t1,•11, 1pr1,•, 1m,111.. 1, •1 11 J•t·r1..t'n1 111 t!w rn11~· I., 1111.111, ~ \\ 1..·1!,~··~i r1l.111i, 1 f" \( '\\ 1 !'\ tr,l~ 1fi-..41 -·~, 11r 111 1.•, 1\,111.1 ... ,11•i•r,1,im,111·h ~. · 1 , HJ l'l r~·:tH .• , fhl w1u' i j J:~;.iir,1rn·~ Ji-·\(') l'Lmi, 1!..1: .;i.· l ... llJ..d, h' 1•1.· l,•111,d rn \\<'!i.H1:1 •. , .. m ''\'!I \1·1·1!.111.t,. .1p1~11·,un.1td1,. \.J 1,1 hf> i p("f,.t'l\l ,11 !ht' hllh' "' 1.·11h,i. . I~ J,:ll_l~.111,·~. 1 ·{~!.'.n,t l'i,11,t, 1 F \("\ ! l;f.,111-< rh.11 ·>•Hr w t!\>ll•\1~·11.11~,!-. ,1rp111,11H,ih·I, I ;,1 I I f'r\.'Ti"1..'l11 •·I lin• 1Htll' ( ll'ih!!,th' t ·pL11lll l'l.m1, i 1 ·p1 .1 1•!.w1•. :h..11 ,,, '-~u m 11,,n ~\ 1.:11.,mi,, 11:1(!,;1 n.1tu1.1I ,: ,,11d11t,,,1-.. ·'['j'l"'llll,1kl _\· ll'J I ':'''"""' Pt 1h.-,..,,.. r-:,, !!;~~;,11:'. j )!~-~ ~r:~"'..1~·-~~~~:~;...!~.'.'\~.:1,,~~~:;..:~~:~ ~~:~:·.~1_1~·-t .... ~~~~, ~·:l~~ :'.~~i1_;~~.::.::~:.1_•1'~,t~!... --~~___,,....._., . !'iourn·: :"-,:,111,•1..il I bl t•f Pl,101 "l'\',·n· .. th.I\ r h, •:: m \\ t·d.111,l, ,, ·: th·,, ,·:.r ( lfrri-·n •11 f' " I 1-.h .111J \\.ddlrk \rn Id' J\11,i,,,.:1, .11 Ri.'j' '!! ,.,, :1, t,, 1Rn ,,,. •. ,1 [,!,, I 1 ..:,;. p f'rc-1..·s \\ 11!11n .1 ~O-li.•1•! r:1drn-. . ...;l)rnh-.. \\ 11liin .1 t :"-1°l1~,1 r,ulhl~ ..• 111d IIL·rh.·, ~··, 1lh111 ;1 ~"li101 riHhu-.; 111' ca .. :h d~H;t pninl \I. CT\.' id1.·ntt li1,,,·d ;rnil nnh:d 1'11i.: ,tppni;\. im,th.' p1.·11 .. ·1,.·11t1~1..· • •f L·1.,·, 1.·r Ii 1r 1..·~1d1 t\ f lhc J1!'kr..:nt plant ~pe1..·1c~ Pl',,:urrmg witlt111 thL· tr1..·\.·. :-,.hrul1. and hcrh ..,lrdt,1 \\ 1...·r.,· \kkr.111111cd. O,m1lnam pl.ml :--pl'\'.'ic..; ,ir1...· ... ·nn~nkr\.·d lo hl' tlh"-1.:' ltM1. \~ ll\.'ll 1.'.'llmubt\\ l"I) htl,1k1.I in lh.'st.:ctHhng orc.lt.:-r t\f ahund.111(1,.', 1.•x'"·l·1...·d 50 pcn.:1.'ttl l,f l!ll..' :J\.'l'l,tl ...:~1\ n fpr ~ai.:h \ i.:g.d~lli\·i...· :--tr;1twn. Any .i<lditinnal :-;pi:i.:i1.•., inJi\l<h.1J\Jy ri:pn::-cnting ~I) pt.•r...·i:11~ nr !,!fl',ttcr ,l!'thl· 11,1:11 a1...•ri;lf ..:,,\ , .. :r for l'a..:/1 \ cg..:-ta:tl\ l' :·arnta ar1,,,• ~1bl, ...:'.l 111:-itkT\.•d J1m1i11Jnt Tht: irnlic-nh1r :-l~UI~ or lh~ lh-minant plant :-.pl.'Ci\.·~ \\·ithin l'.,\dl ,11. thi: \ l.'g1...·1,1tih' strnt..l b U:,il..'d to 1..kti.:nninl' the prc,scnc\.' (1fh:.-drnph~1ic \·C"g..:tation near l'.ach Lfot:1 p11i111. t\ d,:ta pnint t..:,insi(krcd U.l ha\"C hyJwphY1ic ,·cgl·t.:itii.lll i:-:. gr~akr than 50 p1,,,'rl'.t'lll llfthl.' domlnall! pk111t ;,;pcl·ic.s within the ar,'a ha<l an imlical<'f staluc ,,rOBL FA(\\'. ,,r F.-\C. A.2 HYDRIC SOILS Hydril:" soiJs arc <lcfim:d as those that nr~ :-:aturate<l. fmtldcc.J. or pomkd lnng l·110ugh <luring the grt..l\vin,g season to dc\.·clop unacwbic i.:onJiti~•ns thal fo\""Jr the growth and regeni.:ralion of hydroph}tic n,getation. As a result or anacrllbic con<li1io11s, hydric sl,ils e1<hibi1 charadcristics directly obscr\'able in the field, including high org-Jnic mJller c,,mcnl, greenish or bluish gray color (glcy fonnation ). accumulati,>n of sul fi<lic mmnial. sp,>ls of "rang,: or yellow color (mottling), and dark soil col<>rs (t,,w chromas), Tabk A-2. 21-1-12193-001 A-2 ... ... - ••• •• ~=l "" • . a • SHANNON 1., \'VIL.SON, INC , ,nu ,.1 ll\ IJIUC ~011. 1\()1(' \ HIib f ::~d~5-"~I~~~~~···r"::~'.~~(I::;'.'.:;::~~~~ .... :~~.;~.:· :. ~~=~=::.=~-=-~~,: .. -= ·. \ulti.h, \l.l.lr!1,1l · t\.. ti :11 n·.\.'. ,·,f,,1 ~1>d Cuh•r {)dinr11,·r,, '.',.l,1rrn ( l:r,•111.1,,f :: ,,r k ..... Ht n1,•1tk,l ,o11h \,•11,.lr111.1rt·1l ,11 ii -t I••. ,,r I .., f1'l'( 1r .. ,11 •It<.· ,11rl.l\l' hkr,n,l111l· ·~n rl1c ·,,,tl dr.1,n.1!:l' d.,~, .rn,\ rnm,·..1hl 11-. J (,•r .1 -.w111l'l ,ml ·p,·n,•d dm 1111· 1h1· p,, \\ rn·: ... ,.1." 111 Hu, 1i~.th.1Jr, 1h,· ,[,•mm,rnt ,i·l·.-1r.1l .. ,l,·r 111· P.:•L \dl.m. r1n•n. Hue .111d rurpk! t ·1i:._,m.1 ~h·.1"1\\' d r\w runl\ 1\t ,1rt·11j:1h ,1f1hc l·1d1,r •.~~='<.•,•."'-~--.c~.-M...--C..,.,.......,.,.-, o, ,-.,,, -~•••-~•. ,..,,.,., ,., ,-•, -,". ;r.,+' .• ,• ' ....... , •.. ,,.., ---=-~·,,.,.,_....,...,...T',.....,.....,. Sonr.,.,•; 1·n\1t,•w1,\·t1<.1I I .l~ 1.11,,r,. l'i\ -l·,,rr-. ,1 1 I 11,:m~·l•:, \\ ~·ri.111 •. I ... Jh·i111~·.11i,•11 \1.tmi,d I l·,·hn1(,tl lh-pnrt Y-"---l 1 · \ \!Til\. \\'.ll.~·; •.\.I_\, l \.)"!•'(IC\1,"fll Sr.111,.•11 \ :, ~.,h11:·:. ~l1,,1,-.1pr1 l'lw\ 1ughPul .i l.1q;1.; ptn1 i11n \ ,f I l1i..· ;1n:;1 d ... :1111c.1h.'d ~1, \\ l·l.1.111d. 1d~111 i fi\: ;11 h 1n ( 11' h ~·dri L" :-.Pd~ \\' ~i .... . ,idi.:d thn,ugh 1~h:--1.;n. ;11111n 1)f ~urf,H..:1.' hy1..lr,1lt1gK L."har ,11.:t1.•ri-.t i"'-'' ,ind 111,ll\:;1h1r:-. \Ir w1..·lf and hydhll,1g: k.g .. t.lrJill,1£.!..' r.111,:msl. The-l·,11.·nt nfh~dnL" -.nib \\;1-. d1.:tinttl 1hrnt1:!,h dirl'd soil ob:--lT\ ali(lll w1 lhi n ~l·n·ra 1 tbl a p,,inb. pl.h.:..:d htil h i n:--i(h.· .rnd ollhh.k 1 hi.'" ,, 1..·ll:.md. Srii I nh'.'-l'f\"il11')fb \\1,,.'f1,,.' i..:1111lpk·~ld Wllhm ~,iii ill)k,,; dUf \\ 1th a -.hP\f,:I h• ,1 \k·rth 111 at k:1:,.,t I~ indH:s hdt,w lhl.'.' t.:\i~t rng. gr-PunJ ~llrfan· Sllil l)f~antL.:" 1.:~ 111t1.·1H \\ ;h ..::-.1 i Ill ~1h:d \·i:-;ua II y anJ tl':\lur;II I y. s~11l ..:t,lor:,.: were tk·lcm1inc\l thrnugi1 ;maly~l~ oflh..:-h\lt.'. ,·;1lt11..·. :rnd ...:hrnma h1,,.·st rqm..:scnt .. :d in the \lun.sdl Soil {.\,lor Ch;ir1. ,.\ q,11 duoma nr 2 in ..:l1mhi11;11 i(lll with ~oil mottling l}f \I :-.oil chromJ 1.lf I without mcHlin~ 1vpii.:~tll} indi~alc$ ~1 h;,dri..: soil if within 10 inchc:,; nflh\: :,.urface. ~,r din.:ctly hdnw the:\ fwri1.t,n. A.J WETLA'.'iO HYDROLOGY Soils ,,·ere .._~xamin~d for the pn.·:--crn:c nfhydwlvgy. \\"ctlan<l hydrnlogir t.:harac1eristics develop <luring periods when the soils arc inum.folcd pcm1ancntly or p1,,.·rim.lic..1.lly. or when the soil is continuously sa1ura1ed 1,, !he surface for suf!kicnl durati<m to dc"clop hydric soils and lo support ,·cgctation typically 2daptc'<I for l,fo in pciiodic,illy :macrnhic conditions. Wetland hydrology crileria were con,idcrcd lo he satisfied if il appeared lhat wetland hydrology was present for at least 5 to 12 percent ( 12 lO c9 <lay~) oftl1c growing season. The growing season begins when the 21-1-12193-001 A-3 .,,: :, l ""' 1 ... -~ .. ··i ... -<o: -... -~ ~, ·• - - ' ... ,1 .. SHANNON tWILSON. INC ~\,i! l"L';1..:hl.'" a k1Hpl'r,H1ffl' of--ll dq:r'l'l'..; 1-',lhrl·nht'.i! Ill th1..• hllll' ,.frn11l \k .. JJ1:tr;.tlHHI. I ht: !,!(PW(l\t_! _..;.;;.1~1111 1n \\ l.'~ll!rtl \\"~\-.l1i11!!l11n 1, typic,1Hy l'••1hidactl 1,1 hl· Cnim \l;ird1 I 111 < h:IPhi..·r .l I (144 "'by:-.). The Sl-.1Uk 1)1'.'lrid ( ·\\rp:-. n .. ·\.1um:, 1-1 l'Pl\°"l''l"tHi\"l' d,1y::-of 11Hmtbll•.•ll nr -..11ur;1tlnn ,;~r a ~nil 1P he il hyilric .,Pil. lhc hydwh,~)· ,,a:,; "-'valuakd h~ \hrL·1..·t \"lsu.il {'h~lT\i;1t1on 111" smf".ii:l· 111u1alal1(11\ ,1r S\1il s;Huralion \\ ithin IS 111dK·~ hch,w llw L'\l:-.t1ng gt\\~md :-ur{~1 ... ·l' 111 ,.._._.._, pl11h. ,·\l'(Pnhn!; 10th(' I '):-!7 ~,Jamr;tl. ··for ~,Ji! ~;uuri1tH111 tn 1111p~1d \"-'~l~1~1t1,,11. 11 nrnsi ~,'-·cur within il m.i_11ll' pDrt1nn :)f1l11: r11l\t t.\111c ( \l;'IU~Jlly \\'ilhin 11 indll..';\ (l rt b..• :,.tlrfatl') Of lh1,• rrcvafi..'111 \ q!~la!inn .. rfwr"-•for1.•. j f ~illUratcd :-.nils Pf i 11d1t..:al(,r:,:; Wi..'rC nh~~f\ \'.ti \\. 11 hin l 2 i itdh.:s tl r tht..• ~lll"l~11.:1..', p, hl11Vl' indi...::1(0,'~ l1 r· \l't..'tli11H] h_ydn,lt~g.) Wl'Tl.' 11n1cd. The..· .1rl·a 01..~ar ea1.:h ,fa1~1 lh'i11l \\ a~ r\arrn,11..~~1 ti,r 111di'-·,1tnr~ , 1 r wl'I bnt I 11 yd rc 1 lugy. Th1:..:~ indK~lh1r:,; indu1.k drit.:d \\·11lr.::nnmk!-. thin Jim.·.-. .. ,l·dim1..·111 dq,l1,;ih .. 11,d dr,1inag.4.: p;llt1..·1·11:,;, Afl'.L." whcrl' pt1s1li, ~ i ndic;,1t1r;-; tit" h~·\lwh 1g~ W\..'l"l' 11otcd \\"lTl' a;-; ... urn,;d In 1.·nntuin \,·1..·tland h) tirology. 21-l-12\~J .. O'.•Hl.l-,\A ,J.,,c '"t' u,:o 21-1-12193-001 A-4 I ~ :··/· i5·:·r.~ -~:::"_.} , · .r ;·-.;· -~, ,, Former Ribera Balko Short-plat Property Final Wetland and Stream Buffer Mitigation Plan Renton, Washington I ''.' • SHPtNNON &WILSON. INC. ' ' ' ' OlO!ECHHJC ... ~ AHD ~N'WIAONM~/tTU CDHSULUNTS \: ·,,._;•,• .I I! · ,·.1 · . ., .... ,,, fl,o Submitted To: Mr. Tom Foster Fourth Avenue Associates. LLC 6450 Southcenter Blvd., Suite 'I06 Seattle. Wa~~ington 98188 By: Shannon & Wilson. Inc. 400 N 34'° Stmet, Suite 100 SeaU:e. Washington 98103 21-1-12193-004 fl ',1 i ' ~ ,.'Ii ;j l-•i Vl.J, ,J " ., .,, ., . ' - SHANNON ~WlLSON. INC. TABLE OF CONTENTS Page 1.0 INTRODUCTION ................................................................................................................ 1 2.0 SITE DESCRIPTION AND PROJECT HISTORY ............................................................ 1 3.0 FINAL COMPENSATORY ACTION PLAN ...................................................................... 2 4.0 PROPOSED PROJECT ......................................................................................................... 3 5.0 FINAL WETLAND AND STREAM BUFFER MITIGATION ........................................... 3 6.0 PLANTING PLAN ................................................................................................................ 4 7.0 RESTORATION SEQUENCE .............................................................................................. 6 8.0 MAINTENANCE ........................................................................................................... 7 9.0 MONITOR!NG PLAN ......................................................................................................... 7 10.0 SUCCESS CRITERIA .......................................................................................................... 8 11.0 CLOSURE .......................................................................................................................... 10 12.0 REFERENCES ..................................................................................................................... 11 LIST OF TABLES Table No. l 2 Planting Plan for Restoration Arca .......................................................................... 5 Seed Specifications for Restoration r\rca ................................................................ 6 LIST OF FIGURES Figure No. I Site Vicinity Map 2 Final Aulfor Mitigation l'lan 3 Final Pl:mting Plan Typi~al ~1-1-121•11-rl!).\.lllfd,.,.· WI' rn 21-1-1119.~-0()4 ··""/ .. ,J -D i - TABLE OF CONTENTS (cont.) Sheet No. I 2 LIST OF SHEETS Final We•land and Stream Buffer Mitiga1ion Plan Stonnwatcr Pond Landscaping Plan APPENDIX SHANNON &WILSON. INC. Important Information About Your Welland Dcli1l{"alion/Mitigation and/or Stream · Classification Report 2 l-1-l 2 !9_1-tHl4 ii I. ' . I ·'! I 1 1 i ·~ .:~ •·J..(I l .. , ···1 . , ' ·= .. ,, ., SHANNON &WILSON. INC. FORMER RlllERA BALKO SHORT-PLAT PROPERTY FINAL WETl,AND AND STREAM 13UFFER MITIGATION PLAN RENTON, \VASIIINGTON 1.0 INTRODUCTION "!11e goal of tt.1s buffer mitigation v,an is to compensate for unavoidable impacts to the wetla,1d and stream buffer located on the former Ribera Balko short-plat property, as a result of a proposed commereial/residem 11 development. This buffer mitigation plan will establish a native plant community typical of the surrounding undisturbed buffer and is in accordance with the City uf Renton ·s (City's) Environmental Regulations. The scope of work for this project is based on our conversation with Mr. Tom Foster and on our proposal for the property, dated January 2, 2007 . 2.0 3ITE DESCRIPTION AND PROJECT HISTORY The former Ribera Balko property (herein referred to as "the site") is currently an undeveloped. "L"-shaped parcel (King County Parcel No. 5182100020) bounded by NE 4th Street to the north and by residential and commercial-use properties on the east, west, and south in Renton, W ,shington. The site is approximately 5.98 acres, located within the NW\, of Section 15, Township 23 North, Range 5 East (Figure 1 ). The property south of the site has been filled, creating an approximately 15-foot rise along the eastern half of the south property line. Generally, site topography slopes down gently towm-d the southwest side of the property. Maplewood Creek flows sou!h along the west border of the site and exits the site through the middle of the southern border, where a low spot is present amongft the topo1,..-aphic rise along the ~outhern property boundary. Two wetlands were located and delineated by Shannon & Wilson, Inc. on July 25 and 26, 2006. One wetland straddles a portion of Maplewood Creek along the western portion of the property. A second, smaller wetland was delineated along the southern portion of the prope,1y, east of where Maplewood Creek ex.its the site. ll ·l ·1219J--004-RI f tfo\:·WP·Htl 21-1-12193-004 • ·~ i .,., ., . , '~ ·.,) :. SHANNON &WILSON. INC. Historically, the site contained one single-family residence, which was removed during the summer of 2000. Porti<m~ of the property were cleared following removal of the residence. Since then, disturbed portions of the site became predominantly overgrown with non-native and invasive species, such a.s H,malayan blackberry (Rubus discolor), Scots broom (Cv1isus scoparius), reed canarygrass (l'ha!aris arundinacea), sulfur cinquefoil (Potenti//a rec/a), and other non-native herbs. In February 2003, a Final Compensatory Action Program was prepared by Habitat Technologies for the property and approved by the City for impacts to wetlands and the wetland/ stream buffer associated with a previously proposed site development project. Contingent upon this approved Compensatory Action Program, the Washington State Department offish and W\ldlife (WDFW) approved a hydraulic project permit (HPA) (Pennit Log Number: ST-G\585-01), on September 9, 2004 (WDFW, 2004) for work below the ordinary high water mark of a tributary to Maplewood Creek. The approved HPA for the site allowed the placement of a section of tributary to Maplewood Creek (road side ditch} along NE 4'" Street into a permanent underground conveyance (culvert). The culvert was installed on the site; however, the proposed mitigation was not completed because the proposed site development project was changed . ·-· As previously mentioned. the original site development project included impacts to wetlancls. -,; 'I ' ..• Under this revised site development project, impacts to wetlands are avoided while minor buffer impacts are mitigated. This mitigation plan will mitigate for the revised site plan impacts by improving the quality ani: function of the wetland/stream buffer. The revised mitigation will also meet or exceed the goals of the previously approved Final Compensatory Action Plan (Habitat Technologies, 2003). 3.0 FINAL COMPENSATORY ACTION PLAN As previously described, a Final Compensatory Action Program was prepared to mitigate impacts to wetlands, stream, and buffers on site. The originally proposed project included short platting the property into severai smaller parcels for residential and commercial uses. Although the previously proposed project was never completed, portions of the infrastructure were constructed. Those portions of the original project that were completed included installing a t 30-linear-foot pipe to enclose a roadside ditch along the south side cf NE 4th Street and installing a stonnwater pond at the south end of the site. The roadside ditch was enclosed within l 1 ·1·12193 .. fK)4.R I fd,1C1WM'iET 21-1-12!93-004 2 J :;~ ) , ! , II ;~ l!ll :-,, ..q ' <'.i ... ' .,j ····~ J . _,; ' _, .., - .... . ·~ ... ... ., ' ..I SHANNON & WILSON. INC. a culvert to allow for improved frontage and road widening. ln addition to the culvert, the original project proposed permanent impacts to wetland (2,533 square foct of wetland fill) and impacts to the wetland/stream buffer. 4.0 PROPOSED PROJECT The proposed development on the fo1mer Ribera Short Plat property would conslluct two commercial buildings with associated parking along the fromag,• of NE 4"' St';cet and multi- family residences along the central and southern portion of the property with associated parking and common open space (Figure 2 and Sheet 1 ). A stom1watcr pond is located at the south end of the site, immediately east of the wetland/stream buffer. To complete construction of the storm water pond, the southwest edge of the pond must be built up higher. In order to do that, the buffer immediately adjacent will be disturbed. In addition, the outfall of the stormwater pond will be located within the Maplewood Creek buffer in the same area of disturbance . The current site plan for the proposed residential/commercial development (Figure 2 and Sheet I) has been designed to avoid impacts to wetlands anu to minimize impacts to the wetland/ stream buffer. As a result, the approved original Final Compensatory Action Program is no longer applicable. However, the need for a revised mitigation plan still exists because of the unavoidable impacts to the wetland/stream buffer. In addition, commitments were made with WDFW for placing the roadside ditch along NE 4•h Street in an enclosed conveyance. The intent and goal of these commitments, provided within the provisiuns of the approved HPA, have been implemented into this final wetland and stl'aam buffer mitigatirn plan so as to adequately mitigate for tributary impacts . 5.0 FINAL WETLAND AND STREAM BUFFER MITIGATION The construction of the proposed commercial/residential project has been designed to avoid and minimize impacts to sensitive areas such as wetlands, stream, and buffers (Figure 2 and Sheet 1). However, approximately 5,912 square feet of unavoidable impacts to the buffer will occur predominantly as the result of grading and construction activities associated with an engineered wall along the perimeter of the stormwater pond. A small portion of the impacted wetland/stream buffer will be a result of site mass grading activities for future residences toward the center of the site. Impacts are expected to be limited to disturbance of the soils and 2 I •1 ·121 ~J..Q04.R I fafoc/WPIECT 21-1-12J 93-0u4 3 "' • --,j .. , SHANNON &WILSON. INC. vegetation within the buffer. No structures will be constructed within tl1e buffer. The side slope of the stormwater pond will be revegetated with native shnib and herbaceous vegetation. Trees will not be planted in this area for stability reasons. To mitigate for the buffer impacts, the impacted buffer area will be restored (1 :l impacted to restored buffer area ratio); in addition, 5,912 square feet of buffer "replacement" will occur at the north and south ends of the site (I:! impacted to replaced buffer area ratio); and 16,012 square feet of existing buffer will be "enhanced" ( I :2.7 impacted to enhanced buffer area ratio) (Figure 2 and Sheet l ). The impacted buff,,,-will be restored using a diverse variety of native hei-baceous and shrub species, according to the specifications described in Table 1. Throughout the "replacement" buffer area, native shrub and tree species will be installed according to the specifications provided in Table I. The "enhanced" buffer area will be planted with nativ~ trees following the removal of existing Himalayan blackberry (Rubu:s discolor) patches. In all areas where bare soil is exposed through the removal of Himalayan blackberry or grading, the disturbed areas will be seeded with a native seed mix, as specified in Table 2, and then planted with the specified shrubs and/or trees . A cedar split-rail fence will be installed around the perimeter of the wetland and stream buffer -· mitigation areas and storrnwater pond to reduce intrusion into the sensitive areas. A detail of the fence is provided in Sheet 2.0. Signage will bP placed at approximately 70-foot intervals around the buffer area to inform residents and users of the commercial area of the presence of the wetland and Maplewood Creek. A "sensitive areas" sign will be installed ~round the perimeter of the site and a "Maplewood Creek Tributary" sign will be installed along NE 41 • Street. -' ...., -· 6.0 PLANTING PLAN The locations ·of the "impacted" buffer area, "replacement" buffer area, and "enhanced" buffer area are shown in Figure 2 and Sheet I. 11iis plan will establish native, non-invasive plant species in the impacted buffer and buffer replacement areas. The plan is also designed to enhance a large portion of the existing buffer by jump-starting the natural succession process from a Himalayan blackberry (Rubus discolor) and reed canarygrass (Phalaris arundinacea) dominated buffer lo a riparian corridor of native vegetation. The plant species selected for this area are native to the project area and have displayed a high degree of success in similar restoration projects (see Table I below for the plant species selected). In total, this planting plan 2 J -I -12 I 'JJ-004·R I f.doc/WPIFET 21-1-12193-004 4 J : .,_ "" .. .,,f ... 1 .. , 1 '·\ _, 1 : - - SHANNON &WILSON. INC. calls for the installation of approximately 627 native woody vegetation species spread throughout the impacted buffer, buffer replacement, and enhanced buffer areas. A stonnwater pond landscaping plan was also prepared at the request of the City (Sheet 2.0). This landscaping plan is not part of the finalized mitigation for the site; however, at the request of Mr. Foster, native plants were installed to increase the available habitat on site. Planting should be done by hand in natural, randomized clusters. All vegetation should be installed the same day the p,ants are obtained. Plants that cannot be planted within one day after arrival should be "heeled in" for protection against drying. TABLE l PLANTING PLAN FOR RESTORATION AREA w IMPACTED BUFFER Common Name Scientific Name Quantity Size Conditiou Spadng Todianplum Ol!mleria urasiformis 6) 12+ inches 1 gallon/bare root S feet on center Lewis' mock orange Philadelphu.t lewisii 50 12+ incl1es 1 gallon/bare rool S feet on center Tall Oregon grape Molumia aquifolium 54 l2+ inches ! gallon/bare root 5 feet on center Nootka rose Rosa nutkana 70 12+ inches 1 gallon/bare rooi S feet on cenler BUFFER REPLACEMENT ·-Common Name Scientific Name Quantity Size Condltlon Spacing --Douglas fir Pseudotsuga menziesii 41 >J feet B&B 12 fee! on center Indian plum Oemlerio cerasiformis 6) 12+ inches l gallon/bare root S feet on center Lewis' mock orange PMladelplius lfflisii 50 12+ inches I gal1ou/bare root 5 fee1 on center Tall Oregon grape Maho11ia aqulfoiium 54 l 2+ inches 1 gaBorJbare toot S feet on center Nootka rose Rosa nutkana 70 12+ inches l gallon/bare rool 5 feet on center ENHANCED BUFFER 'Common Name Sdentific Nome Quantity Size Condition · Spadng Dougla~ fir Pseudo1.sugo menziesii 112 >3 feet B&B 12 feet on centel' Note: 8&.B '" balled and burlapped plant Slll~k 21.1. \ 2193--004-Rl f.doc/WP/EITT 21-1-12193-004 5 . . f: ..• ~' ··:--..: I ·. M ., ,l .~ SHANNON &WILSON, INC. TABLE2 SEED SPECIFICATIONS FOR RESTORATION AREA NA TJVE DUFFER SEED MIX - Common Name Scientific Name Percent by Weight, PLS California brome Bromus carinahts 10% Blue wild rye Elynws glaucus 60% - Red fescue Festuca rubra i 30% '" " Note: PLS = pure live seed This seed mix should be applied at 80 pounds per acre of pure live seed (PLS). This seed mix will help encourage the introduction of native grass and herbaceous species throughout the disturbed buffer mitigation areas. This seed mix will also be used as part of the stormwater pond landscaping plan. Seeds must be thoroughly mixed before being hand broadcasted throughout the mitigation area. 7.0 RESTORATION SEQUENCE ·-' The restoration sequence is as follows: .., . ., ...J 1. 2. 3. Remove patches of Himalayan blackberry (Rubus discolor) throughout the buffer mitigation areas during the spring of constniction . Procure restoration plants, as specified in Tahle 1, from a registered nursery or through a licensed landscaper and store properly . Place plants within the restoration area in natural, random clusters, as shown in Figure 3 and Sheet I. Prepare the soil pits where the plants will be located by amending the native soil with three inches of compost (Cedar Grove compost or equivalent) over the area and mix it into the soil with a shovel to a depth of 12 to 16 inches. Then dig square-bottomed holes for pi ants, twice the size: of the container, and score edges of planting hole with shovel (so roots can travel outside hole). Loosen plant roots slightly, and place in center of hole, upright and level with ground surface. 4. Hand broadcast native grass seed throughout the disturbed buffer areas following the specifications in Table 2. 5. Irrigate plants thoroughly (King County recommends watering the restoration area with two inches of water immediately following planting). Note: Procured plant material should be prevented from becoming desiccated at all times throughout the restoration sequence. 2 l -I -J 2193-004-RJ f,doc/WP/EET 21-l-12193-004 6 J ··-~ -j 'i :·1 • I , , Ill! ,;J ""I ,,t A¥ : -~; ·~ ·.tl~ • ..J . ! ,, ) - - SHANNON&WILSON. INC. Irrigation should therefore not be limited to post-installation because desiccation will ultimately re<luce the success of the mitigation. 6. Mulch a 3-inch deep, 2-foot radius around the base of each plant with wood chip mulch. 7. Install the cedar split-rail fence and required signage along the perimeter of the buffer mitigation areas and the stormwater pond. Afier the planting is completed, the applicant should request an i'nspection of the planting from the City, 8.0 MAINTENANCE Tiie following maintenance activities should he performed to ensure that the restoration is successful and to comply with City standards: !. Irrigate the restoration area with an above-ground irrigation system calibrated for I inch of water every week from June 15 to October l 5 during the first two years after planting. 2. Replace l!!l plant mortalities during the fall or winter of the first year following plant installation according to the landscaper's one-year plant guarantee. 3. Remove Himalayan blackberry (R11bus discolor) by hand from the mitigation areas throughout all five year.; of the five-year monitoring program to ensure the success of the installed vegetation. 4. Remove fill noxious weeds as defined by the King County Noxious Weed List (http://dnr.metrokc.gov/wlr/lands/weeds/weedlist.cfin) for five years after planting. These include but are not limited to Japanese knotweecl (Palygonum cuspidotum), Scots broom (Cylisus scopari11s), hedge bindweed (Ca/ystegia sepium). purple loosestrife (Ly/hmm sa/icaria), and sulfur cinquefoil (Po/entilla recta) . 9.0 MONITORING PLAN The primary purpose of the monitoring plan is to document the degree of success or failure in the mitigation area and to iclentify adaptive, remedial actions to ensure that the goals of the mitigation plan are achieved. A five-year monitoring program will be implemented, as required by the City, to assess the completed revegetation area and to provide a basis for dete,mining whether the plants are surviving and the goals of the mitigation plan are being met. The five-year monitoring program 21 ·1·12193-004-Rrf.doc/WPIEET 21-1-12193-004 7 t ' I .. ~ . , -' ' _, ~-j · 1 ! .... ' - ',..-.. :·.-•: -~ -.. SHANNON &WILSON. INC. requires quarterly monitoring events and reports during the first year and then annually thereafter, for a minimum of five successful years of maintenance and monitoring. Monitoring reports should consist of the following: I. Percent of plant survival amongst installed shrub and tree species, classified by condition (e.g., vigorous, living, stressed, dead). Quantitative monitoring will occur for all five years within the "impacted" and "replacement" buffer areas and for the first year within the "enhanced" buffer area. To accomplish accurate plant survival calculations, installed vegetation should be flagged annually to ensure they can be relocated during foture monitoring events. Qualitative monitoring of the "enhanced" buffer will occur between years two through five. Note: Perce/1/age of plant survival is not intended to mean the survival of planted material initially installed, but rather should be defined as the ratio of living species following the landscaper's replacement of plant mortality according to the one- year plant guarantee to the number of species initially installed . 2. Percent areal coverage of installed and recruited shrub and tree species. Quantitative monitoring will occur for all five years, per the City's timing requirements, within th~ "impacted" and "replacement" buffer areas and for the first year within the "enhanced" buffer area. To accurately calculate percent areal coverage, the point-intercept methodology will be used at a approximately three and four, 25-foot and/or 50-foot repeatable and representative locations within the "impacted" and "replaced" buffer areas, respectively (see Figure 2 and Sheet l .O). Qualitative monitoring of the "enhanced" buffer will occur between 3. 4. 5. 6 . years two through five. Noxious weed infestation, vandalism, dumping, and other conditions that may be detrimental to the success of the wetland ar,d stream buffer mitigation. Maintenance concerns (e.g., broken irrigation systems, plants that need replacing, noxious weed removal, etc.). Direct or indirect wildlife observations of the mitigated buffer areas, including evidence of nesting/denning, browse, audible calls, and scat. Photographs of the restoration area from locations where photographs can be repeated during future site visits to qualitatively assess the success of the impacted buffer areas, buffer enhancement area, and replaced buffer areas. 10.0 SUCCESS CRITERIA Given the required timing of the performance monitoring events and the often slow growth of plants during the first few years after installation, success criteria have been developed for year one, when monitoring is required on a quarterly basis, and for years two through five, when monitoring is required annually. Year one of a monitoring period is often when piant mortality 2 J-l · 121 QJ-004-RI f.doclWP/Ef.T 21-1-12193-004 8 > ;. < i '9 ,·11 j ,,,,; '1 -,I ·• ' -I .... ; ~• ., • .J 1 , .• ·1.1.: SHANNON &WILSON. INC. is at its highest due to stress on installed plants. Therefor~, the success criteria for year one arc designed to allow for the plants to adjust to the conditions of the site. The success criteria for the mitigation plan include the following requirements: Year One -Quarterly Monitoring I. No more than 15 percent of plant mortality will occur during any year one quarterly monitoring event. All plant mortality will be replaced in the fall of the first year, when plant installation achieves a higher success rate. 2. During the summer quarterly monitoring event, a quantifiable net increase of herbaceous (grassy} vegetation will be present within the "impacted" and "replacement" buffer areas. 3. The buffer mitigation areas will achieve I 00 percent plant survival at the end of the first year, according to the landscape contractor's one-year plant guarantee. See ltem I, Section 9.0 for the intended definition of percent plant survival. Years Two through Five -Annual Monitoring I. The "impacted" and "replacement" buffer areas will achieve either 85 percent survival or 5 percent areal coverage of native installed and recruited woody vegetation by the end of year two; 85 percent survival or IO percent coverage of native installed and recruited woody vegetation by the end of year three; 85 percent survival ot 15 percent coverage of native installed and recruited woody vegetation by the end of year four; and 85 percent survival or 25 percent coverage of native installed and recruited woody vegetation by the end of year five. 2. The "impacted" buffet area will achieve 90 percent cover by installed and recruited native herbaceous and woody species after the second year following riant installation to ensure the stability of the impacted buffer area is maintained. 3. Noxious weeds will be removed within the mitigation area after each monitoring event. Removal may occur according to the King County Noxious Weed Boards recommendations. Noxious weeds are defined by the most current King County noxious weed list, including Class A, Class B, and Class C noxious weeds. This success criterion does not pertain to those species classified as nuisance weeds . If any monitoring report or City inspection shows that mitigation is not meeting these performance standards, the applicant will work with the City to perform corrective actions appropriate to the mitigation (e.g., failing plants will be replaced, other plant species will be substituted, noxious/nuisance weeds will be removed by hand or with approved herbicides provided all local, state, and feJeral permits are obtained to do so}. 21-1 · I 21 ~3 ·004-RI f.doi:/\VP/EET 21-l-12193-004 9 '.:~ I 1 '!! :1; :; ,j I , 'i I ;', :; , ~ ; " J l :i ,. •<j ,, l ,, J ·ii ~ . j J ' j 1 j 1 . ~ ' ... ' \ j ,,, ; .... l '"\ j ' i .J j 1 - l ., I J ,j J ! i l .·1 j ,,.J I .. , ·' I l ! ..J I I -~ I ' I J 'i ; ..J . ' i . ' I ...., SHANNON &WILSON, INC. 11.0 CLOSURE The findings and conclusions documented in this report have been prepared for specific application to this project. They have been developed in a manner consistent with that level of care and skill normally exercised by members of the cnvirorunental science profession currently practicing under ~imilar conditions in the area. The conclusions and recommendations presented in this report are professional opinions based on interpretation of information currently available to us and made within the operational scope, budget, and schedule constraints of this project. No warranty, express or implied, is made. This report was prepared for the exclusive use of Tom Foster and his representatives. We have prepared the document, "Important Infonnation About Your Wetland Delineation/ Mitigation Report," (Appendix) to assist you and others in understanding the use and limitations of our reports. SHANNON & WILSON, INC. PCJ;KLW/pcj 21-l-! 2193-004-RI r.doc!WPiEET 10 Katie L. Walter, P.W.S. Associate Natural Resource Manager 21-1-12193-004 ·~ -' ' 1 ... ' ' ., 1 .J ·~ ·J ! .. -~,, .J J 1 ' ,., "l ..) ., l _. ·1 I ... 1 i ...J --, i .J SHANNON a WILSON. INC. 12.0 REFERENCES City of Renton, 1998, City of Renton building regulations: Seattle, Wash., Code Publishing, Inc. Habitat Technologies, 2003, Final compensatory action program --stream, wetland, and buffer mitigation plan, Ribera Property, City of Renton, Washin;,>ton: Habitat Technologies, February 2. King County, 2007, King County noxious weed list: World Wide Web al: http://dnr.metrokc.gov/wlr/lands/weeds/laws,htm Washington State Department of Fish and Wildlife, 2004, Hydraulic project approval Jog number: ST-G 1585-01: Olympia, Wash., Washington State Deprutment of Fish and Wildlife, September 9 21-1-1210l-004-RI [dodWPIEET 21-1-12193-004 11 j I I ~ ' .\. I ~-.. i 1 1- ' ' ·1 ,·.1 ....... -~· .. I " ~- ..• • ... "i ... a .., ' .,.. ' ...; - ~ ·i ! " 8 ! f {f ~ m ;.; I I!.' .. f "' ~ • fa = ~ . - 0 1N 1a 1 I ::=c:c.:r~.--·:1=:-:=-=-----.-.1 Scale in MIies !i9.TE Reproduced wm, pem,isslon granted by THOMAS BROS. MAP~. This map Is copyrighted by THOMAS BROS. MAPS<>. II is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without peOTlissJon. All rights reseiVed. Former Ribera Balko Property Final Wetland and Stream Buffer Mit,gation Plan ! l Renton, Washin_,g:...toc..n _____ __. VICINITY MAP March 2007 21-1-12193-004 SHANNON & WILSON, INC. FIG. 1 Oeoted!riio::81 ilnct £f>'MJl1manllll Coi<sufta.11b J aj'6(,e,;~.;.L,.,.;:,7rr, · . ,, _, . ·+:i:,;.;,.; ... tr · .,,. ... ·c-·m-.v.m~wL·i#m •?tM,;..;'::":&(<!&,, .. 5£2'f:: :t:::'Ssiiv& ... wfil:t: I:ft -4:--·a; ... ;,..wktnwefr 'ti'-ihs:i i-r:1;;_.:.,,/,;;,;,.~;,.;:>:, ; 'iric~ ~. · g.,-::et;41i,;·;'rl3,,,,~,;~1.@~.:: ~:~ :.~:::: ::..!: :: : :.L:": :::::::--· ··-:::::::::::zr::: ::::;:.:: ::: :: : : :: :: :: ::::::::: :::::~:: :::~:::·:~: :::f.::::: :: ::::::: :: :--·::::::: :.:.L.. . . .. --·. --------------. -. ---------- • • • • --,,._, •• • H•" ••• "" " ---__ _._ .... ---~ ---------- EilUtfl't Repblcement Buff•, lkplaca1r10nl Wotland,. -I \ -\, f30..6"f~ Sqt.1o11't fHl) Categ~ 3 wetland Northeast 4th Street (Renton) Bufftr Repre~nt "" ,. ... ·1 ( ' Bid{ar_Enh•ROefflllnl ~---·'-·-·- @ . ,· . . . ' ~· -.,--,, ) /' . -'~· I'\ . , . . --·""';'i ' ' ' ~.:,;,_,' ·fA . .--.. 1~2~':.·~J /11 :1 !'. lk'liled Sla!BS Post OfrlC8 Renll:lt'l 8ranc-ll w"'°""s [1,'(:11 SqucaN F.al) Wot R•lilulilt.d ~r RMC (+:J ' l --, •I• • ! l LEGEND lm~iiCle-d Buft"ar ~ {5,B12Squwe Feet) Buffer Replacemenl 11111 {5.B1'2. 5qu1re Feet) ~ 6t1ller El1h8ooemant P...l\lUICS (16,012 SQuar& Feel) NOTES 1. Figure adapted rrom efecln:mic ffles prD'lidet.! by ctiant on 1-31-2007. 2. Figura Intended lo accompany S."tMl 1.0: Final Welland And SITeam Buffer MiUgatlon Plan. 0 00 180 E3 I j Scale In Feet F"ormer Rrbera. Balko Proper1.1 Final Wetland and Stream Buffer MHigalion Ptan Renton, Washington FINAL BUFFER MITIGATION PLAN March 2007 21-1-12193-004 ~O!,!~~ J FIG.2 ·, ' ' ' ~ ' ' i I ..... -~--. ·<~~<f~-;.i;! ·:'."~, ~ I ! ! { ~ " i " ' ' ! ~ ~ l ~ il i) ! ,\:' c:·i q,, ,. ri ii! 'j f '.1 I~~ ~ ,.,,.,, ·-~ ~ 1( I I (\ ;11: . ' --!_~ II!!!!! ~ •01111'\dty be.Nd °""" ,~: . . ·,',,. ·y;+' . f; :_.,. ·FY 4z ~.,,;.,;,.;;,. I 14i~ \:q'" tN' ·,:, ~ ~-=-~::; ..... · -4;·_ ··-·'.·., _ ..... , -~~l.:,,r_~_;----· '""""-I 0~.) 0~ 00~0 :· '/!;~# 0 0~ · ... ·.Jf;· ;~~ 0 D 0 00~1!.J 0~ O 0~0 00 0 ~0~0 ~ ,m-o 1~30'x30' Repn,:Sentatlve Area PLAN VIEW -TYPICAL BUFFER REPLACEMENT AAEAS L£;GEN0 Oiffliflltr• cerasibrrril " 12+ lnct.a 1 9allorib:;we ICIOl PhiJadel/,hu1 lewiSN 50 12+-Inches , gallorJban, l'tlOl 5fealcn~ 5fHIMOl!ll'llef Ta,~I -·-.. U• lnd'les ,........,._ 5 feet M C>l'l'ller 1-fooD.altlSII I -·-70 ~ •auanttty baMid on revegetalfon ot 5,912 ~ teet of a,-a. Dig hole. Yilldo and deep nnough to accommodate al! the n>olB wl1hou( e1owdlrig. Planting Sacldffi: Fill hole [ packing the scW to ensul'"lll no alr pockelll; remain. F"rnlshed Gracie: ~ ~·····-vel as was ~ origlmny grov.11. Mound th6 cenltr or tie hole and spread the ,oots &Yenly arwnd U'r9 soil berm. BARE ROOT PLANTING DETAIL 12-!o lnctie$ 1 gdonl'b,;ara root 5 [ee,t,:,n,;;:enl2r :: : ,: : ~ . CONTAINER PLANTING DETAl~ Furner Ribera Batko Property Fir.al Wetland and Sltear:i Bulfe, Mnigation P~o Renton, Washington FINAL PLANTING PLAN TYPICAL Mardi 2007 21-1-12183.-004. ~t'°!j~~ I FIG. 3 :· .... ~··<'i'-·•· ·" ,, ·. 'dh •. Jl::·,· 1.:;r:;;-:rn,~~...,..,.....,.,.,,...~~ .. ~--:efi:111,,,ri;..~.~~~-~l?,~ .. ·~~·<\~·.:;Ji1~ .. ~~..;m#ilt-i&~;.; ~!'".,-~~-.. ,.-~· -----·---·· -,_--..,.. -~-----,·-c-, .. ·=-- .. ,, ·'I •• -·~, '.\:!! . • • ·• ·~ ~ '.~ .. .. ·~ ; "" SHANNON 6WILSON. INC APPENDIX II\IPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION ANU/OR STREAM CLASSIFICATION REPORT 21-1-12193-004 ' \'. ' ' I . .. . I ·-.~ 11111 .I .. • " Ill SHANNON & WILSON. INC. Gix.;1;i;hnLca1 .1r.11 lnw,,rimen1nl Consu!L1ntf. P,IH' . \l.1tdl ~'7, Jfll_l"" i p \1r I,,m .f·,hh'r h,urth "'\"111.H: '''"l.'..i:11L·s LI.( IMPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION ANO/OR STREAM CLASSIFICATION REPORT A WETLAND/STREAM REPORT IS BASED ON PROJECT-SPeCIFIC FACTORS. Wetland tld111c;1tion.. PHIJ~:Hwn and ~,n:;m1 da, ... 1fi<.:,1t11,u rqmrt., ;,ire ha~cd ,111 ,1 um4m• :-t.·1 111" ph1iL'd·'-r1t:..:Hi..: fa~1t1r.-.. n1.:s.: t)lllt,'lll/y . "" mdu<lc the r,coeral n:uur<: ()f !he projccl .i11J propeuy mvl1l\t..J, it, '.'1zc. r:md its i.:,111l"i!!ur:1ln111; h1.~111r11:;il IN' ,lll\l 1lr.;1ct1i.;:t·, th~ k~<.:1.1t1011 ~1f1hc pn.,jcct Llfl chc si1c l'Utd ii;; 11rit·n1;uio11; .ind !he k\'l'l (,r adtlilim1al risk lhc d11 . .-11': :i.,;~l.'uwd by viru11..' 1}f lm1U.tlron:--m,posl!"d upun 1h1..· (':,;pl11rnh11)·p1ogram. ·11,c jurisdiction of any p.m1L·ul.Jr w1:1hmiJ!sCrl'JOl 1~ llct1.·rmincd l•y the fl~ut.11,it)' au1l11\fily{~) 111., .. uinl! 1l1c pi:rmil(:,;.), /\s a rc . .;ut1, 1lnc or m11rc-il~cncic.,; w1ll l,a\'t' JUtisiJkti1111 tl\.""tr a r,.1r111.:ul;.ir wdlmul 111 .,1r~·a111 wHh ~1ttll'l1111t.·:-i ..:unhism~ W;.!t1lali11ns. It ts ncccs~ry tt'l mYt1lvc n t.'••ll.\'Uhafll wlm u111..lcr.-tam1:-wt11d1 i'llWrlt:.y(~l lw:,; JUti.-;i:hcl1<11111wr n pm1icubr \t."\.'Ji;111d .,;ln•u1n ,1nd whnt 1hc ayt•ncy(s} pcnnit1ing ri...-quirt.•mi:nt" ru-t.· for that \\~damb:.1r~·.-m1. T11 hl,.'lp rcduci.: or a\'111t.l pt1C1:n1tal i.:,,,.,1ly pri>hkm:.. h:n·t.· dw ~11u.~ull.lrll 1khmrnm: how any factors-or r<'t:uln[i1111:-: (whidi c,m ch;1nt:l' .;uh.-.c4ucru 1u 1h<: rq'll1tl) nw~' alki.:1 !h1..· tlY1mum•ndaru11h .,. lfthc size (•I cnr1fi~llrn1fo11 l1f1hc pwr,n~<'d rroJct:I t" Jltc,~·<l. .. If I h~ 1(1i:a1it1n tit I llll'l"'l.lli1m t,f 1l1.: prnp1\S1.•d Jlrnjcl'l 1,-( mud1fil·d • !fthcrc i.,; a chan!-!..: ~lft,\,,11·r~h1p. ,. h,r ,,pprka1ion !1) :in ~u.ljm.:cnl !-.1fc • f-'t,r i.:lH1-"lru1:Cion JI .111 :tdJ-in·nt :>lli.' 1u 1111 !-Uc. .. J-'l1llnwio~ l1110J!-o, c.irtl1q:.1.:it....:s. 11r i,Lht.·r ;Kt..,.,ifnaturc. \\'<~1l:111d'slrc.:11n. ;m!iult.;mts camh)t acn-pl fl'.'-!ll'nsihili1y for pr0Mcm, 1ha1 m:i)· iii.'' t.:l11p 1f1ht·:,r-an· Ii<'! ,.;nosultnl ;d\c1 factur, .;,,u:-i<kn.:d 11 i their rcprirli. have ch:mi:.c:J. Tht'rcforc. it 1;,; m..::umbt.·111 up1m pJu lo n\111fy y11ur c111Ndun; nfan)' f: .. 11.:11,r:,, th,,11m1y h,m.~ i.:ha"gl~! prior IO _ s1,.1b111ission or our final rcp,1rt. , \V~tl.111<1 houodanc!i ldcn1ific<l and Slfl'<Otl ..::IJ;s...;1ficntinns oi.11k hy Sh,mnun & \Vil::nn an· o.:,111.~i1lcn._',(,I rrduum;Lr)' 1.1111il ,·ahda11.:d by 1.bc l.!.S, Anny C11rps of Eutinct•r.,; ICt.lrps) .inti \1r the llical JUnsdn:honal .i!!t:'m;.y, v,t11dat1()fl hy lh\:" n.•µ.uh11111~ ui_:rnc~·(:oi) prtlVldc.-: ..a 1,,""t•rufit.·atiun, ....., u;o;:ually \loiincri, thM lh~.-\Vclland b~1~rnJ;inc:,, \"l:tllil-·J mt.· 1hc l1uunJarics 1ha1 will h1.-ri:l,(ulatt•d hy tht.• a1~cw.::,i.'-) un11I ;J SJ11.'...:tfli.'(I date, \If until tht.· rt.•gulm111ns ;irc modified. a11t.l 1h.1t the ,._trcam ha . .:. ln:t.•11 prnpl'rly di!i.::-.ilit·d. t Jnly 1hc rc~iu!.itm~ t1µ,·Pt·)'(SJ c,111 pnwuk th,~ l't.•nilh:.:itinn. -MOST WETU\ND/STREAM "FINDINGS" ARE PROFESSIONAL ESTIMATES. ~ Sitt' l"Xplorntil,n 1t!t.•rHifii:s W\'tlm1d.·str'l"i.lnl cund1lit1i,:,: itl n11ly thost· pn1111,,. wh~rl! sampk~ :trt' lakl·n ,md \,hc-JL 1h,•)I :in· t:1l..cr1, hui the physical f!1i111 me.ans of 11h!;1inmg data prt·duJt· th1c dl'tt·rmm.iti,111 llf pn .. 'l.'1si.: t.·t1nditi1111:,;.. C1111 .... cqul·11tly, lhl" mformatiim nh1aincJ ,s in1l·ndcd h\ hl" sulli.i.::icn!ly accunOi.' for tlt·s,t,;:n. hu1 T!> :.uhjt·t:[ 10 in1~rp1t.•1;:itiun. :\dJ1tinn;1lly, da1,1 d1..'l'i\·t.•d thruugh sampling ,md suh~·qucml bbnrawry .. 1 testing arc c.,;.1rarol,1u:J hy thr.: '-'\msultam who thc-n rt·nckrs an np1m,111ah11u11_\\t.·rnl[ cnnd111~111s.1hc likdy rca,:tuu110 pmp11~tf cnii~lrnction ;:Ktivily, am.l.'M t1pr,n1priall' Jc:,,i~n. Even under 11ptu11;1l l·m·um:-:.tam·c.\, on:1tml cpndi1i1111.,i m.iy difl~r fwm tho,-:l~ choui!hl 11 1 t.•,,i!-iC ht."CJlL-.C no .. c:tlnsuhmH. m1 manc:r hll\\'~t1.;11il1t.'d. ,mti mi t•:<:.pkm.niun pr<,g_ram. m, maltt·r h11w compri:hcu:-;ivc, Ciln reveal \'ffll.tl j.,; hiddi.'il by carlh. rnr.:k~ ,md tfruc. Nothin..:: mu hl· done ltl p(en:nt the unar\11t'q1;1il"d. but slcJ):,; i.:an he taken u1 hdp rct.l\u.:c lh\:"1r irnpacls. h1r thi;-; rt.';L"IOII. 1110~1 '' e.,;;pc:'il'J\i.:cd <1,...11cr:; rclai11 lht·ir t·on~ulrnrit:, throuµh thl· i'.:m1struc1wn {)r wclbnd 11u1i~;1t1t111.1!i1rc::1m da. ... .,ifii.:c1.1ion ::-lagc fo itlcmify ,·11ri,mec.s, aii w c.:,1n(h1ct add.ilional cv.iluations 1ha1 nmy hi: 11ct•dl"d. aod rn nx,irnml·nJ ~nlulinn.s to prohli.::nL-; t·nt·mmit.·rctf un sil1,,•. f ... l .. ... 'j '' WETI.AIID/STREAM CONDITlONS CAN CHANGE. , .... Sm,,:·: nalutul ~y:-h'Ob ,U(" J~·n.11t11\· "').~lrnl., .1lfrd\',f h~ b,,1h 1utur:tl rw~·\·.~~(, ,mil hum;m ,lctlv1t1t·~. d1.mi.."(-i Ill \a·!fom.J bou11d,1ri1''i 1iml :;;lfl'.Jm i.:11111.ht111n." m:l~' h"' ,.·,p,·1.·1t·J. 1 h-1:1;.·(,_,,.:. Jdm\·.11t•d lt.t'lloin,t l->1mnd,!ri,·, .111,I -111~-;1111 1:L1:,;.s1fo:;u11 1n,; ,·,1uu .. 1 n·m,1111 ,,:.1J11f t',•r Jll 1mlcf11111c 1)(-m>J ,,I um~.-TlK' c \,rp .. l)-l'l;,.,11!)· h'\'1·~m1. .. ~-.. rtw \;.h~t1ry 111 \\dl.111,J 1ld.n1•;\l11•rt~ fo, ,1 p,·m~l 11f fi\ t: h',u~ an.:r .,;,1mrll·ll~11t. Snm\~· city :ln\t ~-,,uni~ ,11'.c.'n<.:ll"" u·\ •'t':!Ht'C 1ht· ,,111\hiy ,,1 1,1,·..:1!.md Jdit11..•.1u1•t1~ (ii~., fl\'fh•1l 111' 1,,·1• ~-c-.tr., If a pt.'rll1d ,,r _,..1;,1r~ tr.;1n: p.,~~ .. ·d sim.·,· 1}1..: \\'('ll.anc.i":,;IH.'i'.11n rt•rorl 1, ,\:<-l1•m11lrt ... ·,I. 11n· ~,u.1wr 1:,; :11.l1.:-i:«1i 1,1 h,1\\· lhi: n,n ... ultmll rt.·,.·~.anum'. 1h'-· l\l.'fl,m\l ;...!rc.1m 1t1 \klrr.nu1t: 1f !Ill' d,1.,;,,,1li1:-:t1111n 1~ :\llll at'..:urnk·. C:01\Slmdmn 11r,1.•r.th••ns ;11 ,,r a1JJ,,r,.·ot ll' Ol"..' -..1(1.' ,md 11.,,ur;1I .... , i;;n1~ .~n,:h ;1'1 011,1,h, ... .,,,.,h,111,11...n• ,,r w;11,.•r !lud".it11111~ 01:iy at-:,, ;•fh.·~, ,.·ondi\mn:,; and, thu.,, 1\k· '-<,nr111urn~~ a.,t,.-qu.,,..:'"' l,f lhc 1v{'{JanJ -:1n·,1ru 1cr,.,rt. l"ln: ,..,,n ... oharU ,h,111IJ ht· ~t"fll uppn.,.j;d ,1f 1111y :,mdt ('\l"U1.'i ,ind ... houM b1.· cnn:-ultL'.'d hl <ktcrtm1\c if ou1d111t1n."1l l•"·ah1.ah,,11 i:-nccc .. • .• uy Tlie WETLAND/STREAM REPORT IS SUBJECT TO MISINTERPflETATION, Colitly pn.,hh.·nt,;; ca11 r:ci:u, wh,.·11 pl:trl.,; arc de,·dor,ro t,.,:,:,i:d (111 mi,inlt-·rrrc:-1.111011 tif a W\'ll,111,1 ·.,,:1n.•:1m ~·; r,•rl. ·r., 1,,.,1,, ,1,·,.1id th~i: pr<}hkoL ... tht c~,n,o:uJt~UI ::;:h11ukl \'k; r-ccai11C.'d Iii w~1rk \\1\h oilier 3ppr('l(lrt.1h:-('lrt.ifr~:'llllllill~ 11 1 t'.'\fll,un fl'kn1nt \\'\'tl;tud. "!lrC':.Ull. !!C11lt\~n;1tl, im.f 11lhcr r _·. - -~ Hndint~"· ••nd 11, n·nc•.\· 1hc-;11,k~n.1cy \,f r,fa!I:,;. ,md ... r, ... '<.'1lka11on~ r~l.Ui\,.• ht lht·~ ,.,~Ho.:" DATA FORMS SHOULD NOT BE SEPARATED FROM me REPORT, 1-'in;i.t J"la fnnn:, .arc d~-,~ll'fl'l..'d by lhc-..:l,n.·.ul1.1,11 ha."'--.:1 ,m inlcrpr\'lilti,111 \11' fldJ ~h,.•t:1.,; !..i~~c-mhh,•\I by ~1h.! p<'rs111111d) anJ laborak1ry ,c\illUati,111 ,,f field :-JfllJ'lc:,; Only fin:il d;ila fom1-" cm.:h,nliJ.Hly arc im.:lmkd 111 ,1 Tl'fit•n. The!<'-' dac.;1 fom1:o-shnuld ,,111. undct o.ny .circum~lan\.·cs. hl"' drJWtl for 111':lu.-:i,,n m 01bcr \lrawmg.)i hc1.-;m~c Jr.iftL:"fi m.>y1:unu1111 i:iwo, or ,,m1:,;,,:i11n, m lhL' trmt.4C"r pnJ.Cc:,;..,. Allhc-iui;;h ph~tPttraph11.: re1,roJ.ui:11c111 dmmtaici. 1tu\ pwbkm. 11 dt•cs nothing to r~·1fu~·t· 1hc 1i.1s...;1t,1l11y 11f u11sm1crrn·11ng lht'. furm.,;.. Whi:11 thi:i: occurs. dd:::iy:i., di:.:.pL1lc:-. :rnJ. un;;i.n1k.'ll'•m·d l.'L\"l:-i .1.r~· frl·tw::n~ly 1J1(" rc:-iull To reduce the 111.:l·lih,..,:->d ,1f,L11.i r;.,011 uu:;m.tl"rprciauon, n,r,tr.;i.C'll1r~ • ..:~rn1Xrs. ;m\l r,fam1,:r~ i-lmulJ he 1-tivcn r...·,uly ;i.:-.;:c,"'s lo the c,impklc C~\1r1. "f11>1i-c \Yhr• J1> nul pf'l..)\"1d..: :mch ai:~·c:.;.i, 1n:iy ph,cccd und~·; 1ht• mi.,.;13k,.•1, iu1pn.·,~111n 1!1..1t :-rmply dt:,;daimnli!, rcspon .. ibihty for 1hc ac...:i.ir.1i:y ~if i11form;U1(1n .,1',l·.ir:-in,,;ul;1ll":-Lhc-ni lh:m1 al1C'mla111 h.Jhthl)'. Pm\"1Jm1: lhc h~·;...1 :1v;:nbhle infonn:11mn Ill c11u1n1\.'lflrs. cn~inco.:rs. rmJ pl;um~·rs hdps 11n'\"i::nt it:11~lly probknt" .:md th.:: a~ht.-rs,ui:il 3l1Hmk:--. 1h:1f a1,a~rav;1C\' lh~m 111 ;1 J,:,;.rm1pnni,,ua1c scale. !IEAD RESPONSIBILITY CLAUSES CLOSELY, Oce.1u."c a WL'rhmd \tL"11n..-al1(ln·.,1r..:am da:-;.--,fiQhOl"I ,s b,v;cJ c.-.tcn..:.1wly 1)n Jw.ll,'.HWnl and ,,rinion. ii 1:-f,u lc.,s !.'.,ace 1h:m other Jc-s1~n di::,:dphncs. This sim:Htnn ha..; ll":'IUhL·d rn whtJlly unwarramctl cl.iims bcin~ l\1di;,.•d ag:un~l 1.'(1,11,.~ullanl-.. Tu hdp prc\'cfll 1hi:i prohtcm. -' .:011:mllants h,wc llevc.-l,1rcd a nurnbcr nr..:lausc-.:. f11r 11,.,,.. in writh:n 1r.an,mi1t,1I.,;. n,L~ .arc n1l1,.•xi.:11lpaWI'}' d,1u~:-: de.signed lo fui..-.1 lht ..:('ln;;:ull::m1's linhdi1k•:,; 1,nh) xom,."1trtc clsC": rnthcr, lhq· arl:' ddinit.ivc dau.,c:,,. thut 1Jcu11fy whc1c Hw ..:~:,nsuHanl':,: n::cpon.,iibililic:,; hegifl. and .. ...,, enJ. Thctr n:o.--c helps all p.1r1ico:. in\"tiJv,.--J rc~·l,y.lliN lhcir ill<faiJu.al Tl'Sp1ms1hdilie~ 1.md 1.ih• .:ir,rn>r,ri:ite :ichnn, Sc1mc nftl11:sc dcfini1iw duU.'il~ :1rc ld,cty h• .,prc;1r in yunr C(>J1or1. and ~,1u ari.: t!n..:n11rai;1."t.l 1\, rc,!d lhL'lll d1.)~~·ly. ,\iur ,.·nn~uh.;mt \\ill t,c pk•,a1scd lo@iVC full and ..,;, tfanl-;. am1\\'i.'I"}: 10 your ~uc:,,.11,,m,,. ' THEflE MAY BE OTHl!R STEPS YOU CAN TAKE TO REDUCE RISK Y,,ur consul!a111 mll he pk•a...:cd h} dt:-(11 . ..:,; n!hcr h~,:hnt\!U'-'S (lr dc.,i~1L..: th;11 ,:;m hr \'111pf.,,-~·tl h, milii;.ah: the nsk iif Jday:,: and 1u 1m1vidc a ·, ,•,ni1:ty tif ahcm.atin-s rh;tl may hv l:~.:ndh;iJl w )'()Ur prnJ ... -.:1 .. ... • ... 1 .. t 'uo1t1cl rour i::on?iulum1 for fur1ltt:r mfon11a1111n Pugc ! uf~ I i2lJ01 _J ",-,•.,,, , , ",,II ;(I, I 11,·,11.;,,. 1.11;.•'t•Jl•I mu 1:<1r; .. · -~:' "-•"'" '<",~ .,1,11 ,I<~ Dcccmhcr 29, 200~ Ms. Rocale Tinunm,s City of Renton I 055 South Grady Way Renton, WA 980.57 l. '. \ RE: WETLAND AND STREAM BUFFER MITIGATION INSTALLATION. FORMl(R RIBERA BALKO SHORT PLAT PROPI\RTY. RENTON, WASIIINGTON Dear Ms. Timmons: Shannon & Wilson has prepared this letter to report on inst.,llalion nfthc wetland and stream buffer mitigation on the former Ribera Balko short plat properly (File No. LUA 02-129), Renton. Washington, hereafter refcn·ed to as "th~ site" or "the mitigution sit" ... The goat of the buffer mitigation is to compensate for unavoidable impacts to lhc wetland and stream buffer as a result of a proposed commercial/residential development. The City of Renton (the City) approved the Final Welland and Stream Buffer Milig,1lion Plan, prepared by Shannon & Wilson on March 27, 2007, for temporary impacts to approximately 5,912 squar~ foet of wetland and stream buffer. The mitigation plan proposed to restore the "impacted buffer" and provide an additional 5,912 square feet of"buffer replacement" and an additional 16,012 square feet of"buffcr enhancement." Shannon & Wilson conducted a baseline pcrfonnancc monitoring of the mitigation site on July 16, 2008. As part of the baseline performance monito,ing, a comprehensive plan! count w:is conducted and seven permanent belt transects were established. The results of this baseline monitoring ore provided in our Wetland and Stream Buffer Mitigation B:iseline Perfomiance Monitoring Report, dated September 2. 2008. During the baseline monitoring, we obsc,vcd that the split-rail fence and temporary irrigation system had been installed. Vegetation had been installed in the "replacement," "enhancement ... and "restoration'' buffer ar~,is and mulch (hog !\id) wus rrcscnt in cleared areas 11011h of the stormwater pond. 400 NORTH 34TH srREET · SlJllE ,oo P.0 BOX 300303 $F'ATTLE. WASHING ION 98103 ?OfH13Z•8020 FAX i06·fiQ~;·677 7 TDD 1·800·8J:l·638~ www.sh<m11o,1wilson c01n 21-1-12193-004 ' I '. t ' ' ~ .. :·. ' l ! ' J I Ms. Rocalc Timmons City of Renton December 29, 2008 Page 2 SHANNON &WILSON. INC. EROSION AND WEED CONTROL Subsequent lo the City·s approvnl of the mitigation plan, !he City proposed that the applicant clear the entire buffer of blackberry as u first step to implementing the restoration, and they asked that the native vegetation be pc·eservcd where possible. In early September 2007, to accommodate the City's request, buffer areas we,·c cleared of Himalayan blackbcffy (sec As-built areas I, 2, and 3) and native vegetation was preserved where possible (see As-built areas 4, 5, and 6). Prior lo clearing ofbiackberry and site grading, a silt fence was installed near the wetland boundary and along the tributary to Maplewood Creek for temporary erosion and sediment control. Following the buffer cleanng in September 2007, approxirnatel.y 6 inches of mulch (hog fuel) were spread over cleared areas to suppress blackberry growth and to stabilize lhe buffer from erosion. fn their March 14, 2008, letter, the City's consulting biologist, Otak. recommended that the mukh remain in place and that ;,>rass seed should i:ol be spread over the mulch. At the time of our baseline monitoring, mulch had been placed on site in areas where clearing occurred, except in areas along the perimeter of the sto1m pond and on the western slope north of the Maplewood Creek culvert. The applicant has said that they intend to place mulch thovghout the entire cleared buffer area at a later date as part of ongoing site maintenance. PLANT INSTALLATION During our b3scline monitoring. we observed that fewer plants than specified in the appro"Cd mitigation planting plan had been installed southeast of the isolated wetland, south of Maplewood Creek culvert, and along the western perimeter of th<: stonn pond (sec As-built 3rcas 4 and 5). Since the baseline ,r,onitoring, additionnl plants have been installed and th~ total number uf plant installations exceeds the quantity spcciticJ in the approved mitigation plan. Tahle I (as follows; summarizes plants installed on site and compares those to plant quantitks spcei ficd in the planting plan. ;. ' ~ 1' '. ' ' . ~- f. t 1- Ms. Rocalc Timmons City of Renton December 29, 2008 Page 3 SHANNON &WILSON. INC. TABLE I PLANT INSTALLATIONS BasfUne PlanL• Installed Planting Plaut after Totnl Plants Common Name Scientific Name PJnn 1 Count2 Monitoring 3 Installed Indian plum Oemleria 126 88 50 138' cerasi/i;rmis -- Lewis' mock orange Philad,..>Jpli11s h:ti'isii 100 105 12 117' - Tall Oregon grnpe Mahmrll1 aqu{!Olit•m 108 111 9 120' Noolka rose Rosa 11wlwna 140 134 13 147 4 Douglas 11r P.w•wlo1suga 153 124 29 153 menziesii TOTAL I 627 562 113 675' -· Notz..'i: I. As specified within Table I of the Fonner Ribera Batko Shon Plat Property Final Wethmd and Stream Butfcr Mitigation PJ.m (March 27, 2007). 2. The baseline plam C(:unl occurr~d on July 16, 2008. ft is likdy tlu11 ::1omc plants were missed during this plant count due to either their size or mor1alitics. J. Seventy-three (73) plants were in~tallcd in late Augusl/carly September (see enclosed e-mail and figure provided by 0.ffe Engineers Jnd check for $860.86 lo Rosso Gardern;). Forty planL.:: were in5t..11led in earlf Decembl!'r 2008 (see enclosed invoice for $519.49 from Rosso Gardcn.sJ. 4. Exceeds quantity proposed in approved mitigation plarn-ing plan. -- 'Vlinirnal planlings have been installed in the areas southeast of the isolated wetland (sec As-built area 5), south of Maplewood Creek culve1t (see As-built area 4), and along the eastern boundary of Wetland A in the northern portion of the site (sec As-built area 6). These areas are currently vegetated with dense. woody, native vegetation. For areas that were too dense to plant and where clearing would disturb the native vegetation, plants were reallocated and installed in other portions of the mitigation site. These areas (where dense native vegetation was retained) will still continue to be subject to the mitigatinn pcrfonnance success crilcria and will be maintained for weed control as required within the approved mitigation plan. As well as installing additional plants within the approved mitigation site. 44 native. woody shrubs have been inst~llcd in a dcared area north of the isolated wetland Jnd south of(within) the split-mil foncc (sec As-built area 7). '.'l,J 111'11111~.l.~d,.._. ..... ,,tKll 21-1-12193-004 ...... i j Ms. Rocale Timmons City of Renton December 29. 2008 Page 4 SIGNAGE SHANNON &WILSON. INC. Thirteen "Sensitive Arca" signs were installed along the split-rail fence at approximately 70-foot intervals and a .. Maplewood Creek Tributary" sign was installed on the split-rail fence facing NE 4'h Street (based on an e-mail and a sketch provided by Michael Brown of Langley 4'" Avenue Associates on October 30, 2008). CONCLUSION Based on our site visit and the information provided by the applicant, we believe that the installation of the mitigation has been completed adequately, except for the application of mulch in cleared buffer areas. The As-built drawing and this letter reflect where the plans deviated from the initial approved mitigation. With the exception noted above, these deviations were done to adapt to the site conditions and should be approved by the City because the installed mitigation meets the intent of the approved mitigation plan. CLOSURE The findings and conclusions documented in this letter have been prepared for specific application to this project and have been developed in a manner consistent with that level of care and skill nonnally exercised by members of the environmental science profession currently practicing under similar conditions in the area, and in accordance with the terms and conditions set forth in our agreement. The conclusions and recommendations presented in this letter are professional opinions based on interpretation of infonnation currently available to us and are made within the operational scope, budget, and schedule constraints of this project. No warranty, express or implied, is made. .' J-1-r 21 Y\ (K),1 r ,I du,::1>r I.Kil 21-1-12193-004 ' . •· ' ,. l t { .· i' .. I r 1 . :r- :., . r ,_ Ms. Rocalc Timmons City of Renton December 29, 2008 Page 5 ,,,-,·-:·· SHANNON &WILSON. INC. We assume that the City will provi<le written confinnation of acceptance of the As-built. If you have any questions, please contact me directly ut (206) 695-6876 or via e-mail at bxe@shanwil.com. Sincerely, SHANNON & WILSON, INC. Brooke Erickson Biologist BXE:KL W /bxe Enclosures: Sheet I -Wetland and Stream Buffer Mitigation As-built E-mail from Offe Engineers, November 18, 2008, With Attached Figure Check No. 1077, Paid to Rosso Gardens on Aul,'llSt 30, 2008 Invoice No.7100833 From Rosso Gardens, Paid December 9, 2008 c: Tom Foster, Fourth Avenue Associates, LLC' 21,1-121'1~-1104-1.-1 J.-i,; 11·r LKD ll-1-12193-004 ' }'. . I Former Ribera Balko Short-plat Property Wetland and Stream Buffer Mitigation First Quarterly Performance Monitoring Report Renton, Washington City of Renton f'l~nning Division AUG O 6 2009 ,SHANNON 6WILSON. INC. · July 30, 2009 (aOT[CHNICliL ANO f:N~tAOHl1UCNTAl C0ff9LILT ... Nl'lil Excellence. lnnovation. Service. Value. Since /954. .Submitted To: Mr. Tom Foster Fourth Avenue Associates, LLC 6450 Southcenter Boulevard, Suite 106 Seattle, Washington 98188 By: Shan~on & Wilson, Inc. 400 N 341 Street, Suite 100 Seattle. Washington 98103 21-1-12193-005 :, . " I I • ··1 I .'.) I . ' I ·,: ·:t 1 ' I ·' ., I I ·~ a ···/ I ·, ., i.il 11 ,. = ;i ' .--~ ' } ''ii ;. 1j ill '1 iii ~/ t~ 1 • ','f (1 ':1 .-'? ml ' d 'j nl ~ ·:--'· .. SHANNON &WILSON. INC. TABLE OF CONTENTS Page 1.0 INTRODUCTION AND SITE DESCRIPTION ................................................................ 1 2.0 PERFORMANCE STANDARDS ............................................................................... 2 3.0 4.0 5.0 6.0 PERFORMANCE MONITORING ................................................................................... 3 METHODS ....................................................................................................... . ........ .4 RESULTS ...................................................................................................................... 5 5. i Plant Survival and Cover ........................................................................................... 5 5.2 Noxious and Nuisance Weeds ................................................................................... 6 5.3 Maintenance Concerns ............................................................................................. 7 5.4 Wildlife Observations ............................................................................................ 8 CONCLUSIONS ...................................... , .......................................... . ........... 8 7.0 CLOSURE .................................................................. . ..... ' .................... 9 8.0 REFERENCES ................................................................................................................... !O TABLES I First Quarterly MonitoringTrnnscct Sampling Results .......................................... 6 2 First Qum1erly Monitoring Noxious and Nusiance Weeds........... . ...................... 7 FIGURES I Site Vicinity Map 2 First Quarterly Monitoring Mup 3 First Quarterly Monitoring Photopoints APPENDICES A Performance Monitoring Data Sheets B lmportunt Information About Your Wetland Delineation/Mitigation and/or Stream Classification Report .' 1-1-1219.1-00S·R I .,Jor;.Vwp.'ctp 2t-1-t2193-005 i! !·.-1 ~ ,'f. .. '1 !Ill SHANNON & WILSON. INC. FORMER RTBEIU BAI.KO SllORT·PJ.Xr PROPERTY WETL/\NI) 1\NI) STRE/\~I BUFFER MITIGATION FIRST QU,\RTERLY P~:RJiORMANCE MONITORING REPORT RENTON, WASlllNGTON 1.0 INTRODUCTION AND SITE DESCRIPTION This report presents the findings ofShmmon & Wilson. !11c.'s (Shannon & Wilso11's) tirst quarterly perfonnance monitoring ot'the wetland and stream buffer mitigation on the former Ribera Balko short-plat property. The purpose of lirsl quarterly pcrfonnancc monitoring is to assess the buffer mitigation (0 provide a ha sis for dctcnnining whether the goals of the mitigation plan arc being met and, if necessary. to ide11tify adaptive or remedial actions to ensure that :he goals of the mitigation are uehieved. The fonncr Rihern Balko short-plat propeny, hcreatler referred to as "the property," is currently an undeveloped, "L"-shaped parcel (King County Parcel No. 5182100020) bounded by NE 4(h Street to the north and by residcnti.::il rind cornmcrcinl-use properties on the cast, west, and south in Renton, Washington. The property is approximately 5.98 acres and located within the NW \s of Section 15, Township 23 North, Range 5 East (Figure I). Maplewood Creek flows south along the west bonier of the property and exits the property through the middle of the southern border. In 2006, Shannon & Wilson delineated two wetlands on the property. One wetland straddles a portion of Maplewood Creek along the western portion of the property. A second, isolated wetland was delineated along the southern po11ion of the property, east of the point at which Maplewood Creek exits the site. Mitigation was approved by the City of Renton (the City) in order to compensate for approximately 5,912 square feet (st) of unuvoitlablc impacts to the wetland/stream buffer as a result of a proposed commercial/residential dcvclopmcnl. Buffer impacts are predominantly the result of <.;onstruetion of an engineered wall along the western perimeter of!l1e stom1water pond at the south en<l of the property. A small portion of the impacted wetland/stream buffer is associated with b'Tading activities for future residences toward the center of the property . 21-1-12193-005 .., I ~: ; : .tJ ''•I . " .. , ' ... SHANNON &WILS0i I, INC. The approved Final Wetland aml Stream Buffer Mitigation Pl;in prepared by Shannon & Wilson, dated March 27, 2007 {Shannon & Wilson, 2007), was designed to cstublisil a native plant commu,~i ty typical of the surrounding undisturhed buffer through buffer restoration ( 5, 9 12 sf), bufter rcplacemcnl (5, 'I 12 st), and butler cnhanccmcnl {16,012 st). 2.0 PERFORMANCE STANDARDS Following its approval of the Final Wetland and Stream Buffer Mitigation Plan, ihc City proposed that the applicant dear the cnlirc buffer mitigation site oJ'hlackbcrry prior t<' restoration. To ,•ccommodatc the City's concern over controlling blackberry, the buffer mitigatmn site was cleared in September 2007, while preserving the native vegetntion where possible. A tkr cle"ring, 6 inches of mulch (wood chips) were spread lo suppress growth of blackberry and to stabilize the soil surface from erosion. These activities (done to accommodate the City's request) affected the perfom1ance stmldards within the approved buffer mitigation plan. Shannon & W1!son proposed revisions to the pcrfomrnnec standards in a letter to the City dated January t 5, 2008 (Shannon & Wilson, 2008a). The City approved these revisions with moditications recommended by the City's consulting biologi,,t in a Tcdrnical Memorandum dated March 14, 2008 (Otak, 2008). The final pcr.fon11ancc standards, as revised by Shannon & Wilson and Otuk and approved by the City, are summarized below: Year One (Quarterly Monitoring): • • • • A minimum of85 percent survival of installed WC>ody vegetation during any quarterly monitoring event, or no more than 20 percent plan! mort(l!ity of installed woody vegetation for the first year within the entire hulfeJ' nreu. No more than IO percent areal cover of Himalayan blackberry (l/11b11s di.l'color), reed canarygrass {Phalaris anmdinacca), English ivy (1-tedera helix), and species listed by King County as Non-designated Noxious Wce<ls and Weeds of Concern throughout the entire buffer "rca. At the end of the first year, a wetland biologist will detenninc the extent of plant mortality that took place during that year by making a ct>mprchcnsivc plant count of the entire hutrer a!'ca. All plant mortalities must be repl,rccd d~ring the foll or winter following the first year alkr plant installation. If plant mortality is greater than 15 percent following the comprehensive plant count, appropriate cotTcctivc measures will be taken to reduce the potential for ti.trthc, die-back. ,1-1-12193-00.1 2 J ! ,.., ''I . ; '·;:!I . ' ., ' .. , ,; ., ···• ;·.'1 '< .. , . I :t ~ .... u Iii SHANNON &WILSON. INC. Year, Two to Five (Yearly Monitoring): • • • • A minimum of 85 percent survival or installed woody vegetation through year lwo within the entire huffor arcn. A minimum of85 percent survivul ,if installed woody vcgclalion 1hr0l1gh year live within the '"enhanced" buffer area. f-..1inimu1n areal cover of installed woo<ly vegetation und volunteers 1.lf c.ksirnblc naiivc woody vegetation of 30 percent by end of year lhrcc, SO pcrccnl by end of year four, and 70 percent by end of year fiw in the ··restored"' aml "rcpluccd'' buffer areas. No more than 10 percent aerial cover of Himalayan blackberry (Ru/ms discolor), recd canarygrnss (P/iabris ,,:·•mdinacea), English ivy (lledero helix), and spectcs listed by King County as Non-designated Noxious Weeds and Weeds of Concern througbot1t the entire buffer area during any yearly monitoring event. • After each monitoring event, 1-limalayan blackberry ( li11h11s discolor), recd canarygrnss (Plwlaris an111di11acea), English ivy (lkdcra helix), and species listed by King County as Non-dcsignatc<l Noxious Weeds and Weeds ot'Conccrn will be removed throughout the entire buffer urea . Note that ''percent o(plant surrira/" is intended to reJ{ect rhe J}('J-centage c~lliring tre(! am/ shrub species initially in.stalled and any subsequ.e111 plan( replacements H"ilhin JIH· representarive sampling transects (not including 1·ccr11ifcd specirs) relative to the numher of tree and shrub .species recorded during the baseline monitoring 1:i·c,11. Al the request of the City, a stom1watcr pond landscaping pl,m was prepared and submitted in the Final Wetland and Stream Buffer Mitigation Plan. The stonnwatcr pond landscaping is 1101 subject to the performance standards or performance monitoring requirements within the buffer mitigation plan. However, the City will require successful establishment of the stomm•ater plantings, as well as other landscaping (e.g., slre~t trees or siniilar) associated with Ilic site. 3.0 PERFORMANCE MONITORING The Cily requires performance monitoring ot'thc hutfor mitigation site for a period of five years. The monitoring program consists of a hascliiic rcporl loilowctl by quancrly moniroring events and reports during the first year and then annually thcrcattcr. Tallie I pmvi,IL-s u schedule for monitoring events. Aflcr cuch monitoring cvenl, a pcrl{1111rnncc: monitoring report will be prepared t0 document the degree or success or failure in the buffer milig<1lion site and to identify ad<1ptivc, remcdiul actions to ensure that the goub t.1f the buffer mitigation phm arc Jc.hi('vcd. ----------··---------·---------------·--·-------~-------------- !1-1-1!1'1_1 1111~-R I J1...-" •••r d11 J l-1-1219)-005 3 t r: ,. ,. ii .. . -~ SHANNON &WILSON. INC. On July 16. 2008, Shonnon & Wilson conducted baseline monitoring ol'the buf'Jcr mitigation site, which irn.:lmJcd a comprchr:nsive plnnt counl and c:itablishmcnt of:-:L~vcn pcnnancnt bdl transects and four permanent photopoints. Our baseline monit<,ring fou11d that 73 additional plants were rL'qUircd lo meet the buffer mitigation planting plan (Shannon & Wil.son, 2008h). Additionally, signagc had 'IOI ycl been installed in accordance with the buffer mitigation plan and some ureas lacked mulch. Aller our baseline monitoring. 11 :l addilionnl plants were installed anJ signs were pos~ed ~ceonling to the City's requirements. In accorduncc wilh the City's request, we prepared an installation letter am! as-built drawing. dated December 29, 2008 (Shannon & Wilson, 2008c). The ,;chcdule for performance monitoring events is prnvidc,I below. Due to a delay in finnl approval of the mitigation installation, this monitoring schedule was adjusted from the schedule proposed ill our Eluscline Pcrforniancc Monitoring Rcpo11. • • • • • • • ' • Baseline -(completed July 16. 2008) Year One, First Quarter -April 2009 (completed May 4. 2009) Year One. Second Quancr ·· July 2009 Year One, Third Quarter -October 2009 Ycnr One, fourth Quarter -Dcccmhcr 2009 Year Two-· Falt 2010 Yem Three -Fall 2011 Year Four -Fall 2012 Year Five-Fall 2013 ~.O METIIOOS The first quarterly monito1ing was conducted on May 4, 2009. lo record conditions of the mitigt1tio11. Vegetative monitoring was conductc(l using seven hclt tnnsects (Figure 2). Plant survival and condition (e.g., vigorous. living, strcs!:icd. demi) of instnlh::d \'tOo<.ly vegetation, percent areal cover ofinslullcd an<l 1..!C$irablc native rL:rrnited wom.ly \·cgct,1tion. and percent areal cover of noxious and nuisance weed~ were recorded. Mnintenuncc cnncems and other conditions thar may be detrimental to the success 01'1hc· 1>1ilign1ion and dirc,·t or indirect wilcllil'e obscrv~1fion.o.,; were rccurckd for lhc butlCr miligulion silc. Plwtr.graph.s ,vcrc taken at the four photopoint locations cswhlishcd cluring (he ha:-;dinc pL'rfonnancc mrntito1ing (Figure 3). The seven bell tran.scct s;nnp!ing plots were established during our lmscline ll1()J1itoring and ;,1rc markc<l with gr~~n n11...:tal fence :-.takes. A tapL: rule. disp!aying inch~ and tCet. was ::,.panned across the lop of the metal st;ikcs. forming one axi~ of thl' transect (y-axis). A 5-foot-long .'1·1 1:1ir11~,, l<l,l,,.-,,~1,,1i, ':1-1·12193-0fl~ .\ J ·{ SHANNON &WlLSON. lNC. 1111.·a:-.111111~· .... 111.."I-:. 111;1rkl·d wnb lerllhs 1,r a liinL w;1s held pcqJL·11diL·ul:1r lo 1lw I.ape rule l<l l{m11 lht.:: ,,,.x,1rnl ;1\1\ ( 'i··:1.,1s). Sa111plt11Jt \\'a~ l'\IIHlt.h'lol hy wcilking paralkl to !111.: lapl' nik· and holding, th;__· H\L'Hsuring stick k"d \\'1111 ~,11~: 1..•nd !lush \-1,·lth ila.· tap1..' nilc. \.Vl11.:n \Vornly \'l.'~ct:llion wa.s e11c..:ounlt..::r\.'d, the width n r 1\w p!.1111 along l hL· ,1.;-:1.x i .... anti y-nxis w;1s n .. ·1..·on.hxl. i> t.:n.:l'll1 aeriul L·u \'l:r l) r in-;la !led and tksnahh.• 11atin: n.·1. .. TuilL'd w1iudy \'l:t~cl:1tw11 wa:-; rulculat1.·d by ttH11liplyi11g widlh u/'tl1L' phmt ,drn1.1_.'. !h1..· x -:1..;1:-, 111111.::-. thL" widrh ,ii tile p\a11l ah inµ lhL' y~.ixb. \VliLT1.· ln:L· can,ipy ,v,1,o,,; c1h..:u1111h:rL'IL ~iµ11ilica111 VL'l'lin~s witllin lhl' (l'allSL'• .. :l \vcrL· l'Cl'Pnlcd In di..:linL' lhc an·,1 of c.:.111opy u,, L·r. Pcrc-..·111 ;1rL·al 1..:on.T of hnha1..·tous spL·<.:i1.,;~ ,va~ ,·isually t:"sli111.1ll'd o,·cr 1hc Int al plot arl'a to dcll·nnin1..· 1l1t.: ahumbw .. :c nf110:xious and nuisam.:c w1..·cds. f ·I j\ ~ .. : t ,. ~ i •• ·.-Jj ' ., 5.11 ,u:st,LTS 5. I J>brnt S11rriv:1t ·.rnd ('over 1 )uring our firs! qu:irlLTly nwniroring, we ohscrvL'd lha1 :,;oml' of ti,,._. instilled plauis (Douglas fir :111d l11dia11 plum) Wl'rl' ·"llowing signs pfstrL·ss \i..·hik others :1ppl'ar1..·d lo h..: lhriving. fn total. plan! survival w;1s lJJ JK-ri.:cnl (T.:,hlc I). Pcn.:l'rll survivnl included only in.o,;talkd \·cgctntinn .. nmsist ing of Indian plum (( )('m/c•rio < ·c 1 n1.v.(/i>rmis}. Lewi:-;· mnck nrnngi: ( l'hiladdpfws lewisii), Tall Or1,;go11grapc (.\Jahonio Ot/Ui/iJ/ium), NotHka l\):,;c (Roso 1wtko1,a). ,u1J Douglas Irr 1 f'seud0Jx11J.:" mF!11::.iesfi). Thi..! ,xm1bim:d ari:~il co\'cr during our Jir.s.l quarll'r nwnitpring was I-l 2 pnci:nl (T11hle I). Areal t:lJ\'1:·· ii1cludcs all dc:-;irahlc 1mtiv..; WlH_aly vcgct:1tiun indudi!1g in:-;t~1ilcd :mcl n .. •cruit~d vcgctalion. Areal c...:ov,·r from r1..·crmtcd vi.:gct;,1lion within .s.mnp!ing plt\lS primarily came from h!ack co//fJ/!Worxl (/711'//$/.!"~Q/r,-/,<W)f'=/ 3//// W///m;-r,JJ/d.i·.,;;./.s'1p//r1g.s: Appo,m:r A Ct'N//3//,S' pc:rfbnn.uncc monitoring lir.:ld <iati, s!rc:c:ts. :'.!l-i-1~!9J.1)(15 ; J t ' ·, SHANNON &WILSON. INC. TAIH.E I Ffl{ST QUA HTl•:IH, Y MON ITOIUN<; TIUNSE("I' SAi\l l'I.INC 1H:St1LTS "~'" ''f"''·or.,,·,-·, ,.· .. ,. • -,., ',r, .. ,,., • ·1·=-~".0<·,·r,., 'I Transect Tr:mi,('ct Ha:i:clinc Numh<>r of l)imensiun~ t\t'l}a Number or ,\.,urvivin1-: T1·,1uscct ..... .{~!•') (•I) l'l,.uts 1 l'hrnts 1 25 _'( 10 .111 25 .-. IO .I c:-, 111 )) 1 .J l 5o'(s .'!:~o ')) 21 , r HHl.,.i 1 ,.H, Ill 7 (1 I ~~'(10 ~"if} 20 I) l'crcrut I Surviva! Xh ! JO.I I I 'lo I I 11111 Percent ,\i;•riul Covrl X.'J I .J. J I S o lid 11/;1 I SJI [ {) ,(1 ,}-~-r~;l~-L~~2:1~~~ -~----~:~~ ~-----___ --~;. ... -':! __ .. ,L-J..:!}--- N1}l1..·:-.· I N11111hl'I' ,,J 1i!a11h 111dudL'!i IIJI[\' iri.,;1.1/lnl ~ q!t'l:ili1111 :-.p,:..:t liL·d \\"lthrn 1h1..· ;!ppr,n·1·11 plat11in~ pt.m Sl'l' I ;1bl,; I ,,rn1~· ~·in.ii \\\•d;md :111d S1n:am Buffn .\11t1).!:11io11 l'l.111 (Sha11111111 &. \Vil'it111, ~110.,l NwnhL·1 \If ~\ll'\·tvi11.i.: pl.:mls i•. die null1h1;r <)f 11i,,;l;ilktl , ..:,:,:d;1t1,,11 ,,h..,1.!rn·ti 1!11nn;: dh' lirsl qu,nll! ly 111rn1ir.•rn1)!. ~·,...:111,hnJ.! dvad pb,H~ ' l'l"!"l~·111 ;,c1i,1I i.:1\\1.1· i11ch1dcs l'!t,(li ms:.ilkd ,·,..t.:..:lalinn ;uttl ,k:;irnhk rL"lTl.Bki: 1,·~11111\· '."l"C~l:11n111 1 P~rl·1.·nl ill:fi;\/ \.:tWi.'f w;is 11111 r"l\:1ll"d~'\l 11,1 lho.: .:l·11h:11wL·d .. huOCr :lt'-'ll \I hi.:rl' ,ml}' l)1111gl;;_, !i1 \1;1~ i11s1;1llc,I ~j s,:u.in: f..:d S.2 Noxious and Nuisance \Vceds During vur first qua11crly monitoring, weeds were abundant along the pcrimclcr of the stormwatcr pond and north of the Maplewood Creek nilvcrt. Where sullicicnt mulch had hcen plal'.cd. such as at the northern portion uf the site, weed were less ahumlnnt. Maintenance work to control weeds hy hand anti apply mulch throughout the mitigation siic was conducted after our monitoring visil. We con<luctctl a follow-up vi~it to the site on July 16. 2U09. 10 observe lhc weed control efforts. Maintenance work was in prngrcss during our July 16, 2009, follow-up visit. Al the lime of our May 4, 2009, monitoring. we ohserved several species listcJ by King County as Non-designated Noxious Weeds or Wec,ls oi'C'oneem lo be established in the butler 111itiga1ion site. These species a•c Himalayan blackberry (Ru/,,,.,. discolor), r,·cd canarygrnss (Plralari,l anmdinacet1)~ Scot·s broorn {(ytis11s scoparius), Canada 1hi.stlc (Cin:ium an·c11se), und creeping hutten.;up (l?animculus repen,·). Wt: observed ~muller arnounts of Rohi.::rt'::; geranium ((icranium roberr;mwm} and field bindweed (Connitntlus an·ensil), which are listed by King County as Non-dcsignntcd Noxious Weeth:. Tansy ragw(1rt (Sene'civjacoluu..'tl). iistcJ by King County as a Cl.:1ss B Noxinos Weed~ was observed [11,..;m;:1]1 amounts along the snulhcrn property () ~- ~; ~- J • ·'i SHANNON & WILSON. INC. hmdcr. ,\llhough Class ll Noxious Weeds arc ,wt incllidul :11 lhc pcrfomrnncc sl.indanl, for I his 111iligalion :,;ill:. the siak wt·cd law (Rcvi:-.t.•d Ctide nf \V;,isilington 17. I 0) requires prnpL.!rty lnvncrs tnnm1rol and prcvl:nt 1hc :-;prcad \)f('las;; B Noxitn1s V./c:t:(ls. Based on the r4.!~utts of our vcgcti.ltion sampling \.'.OIHlur...:tcc.1 on May 4. 200(), the pcn.:cnl arc~1I covt•r of Sf'H.'cic:,; listed by King ( 'ounty as Non-designated Noxious \Vl':cds or Weeds of Concern C~t.;ccdcd I() pcrccnl. lfowcvt:r. areal covt·r cstinwlcs L,1k1...:11 during our follow-lip site visit on July 16, 200'1. dclcnmned lhil weed cover had been r~duccd lo 95 pcrccnl {Table 2). We urnlcrstand Owl dTorts to t:h:ar weed:,; tbroughout lhc entire site continued .rdkr our July 16, 2009. visit. The Clly n.:,1uin::, th:1t weed 1:t1ntrol he compktcd using mnnunl 1:ontrol mdhods nml will allow appropriulc hcrbiddc use only a!kr all manual conlrol mclhods haw foiled (Oluk, 2008). If han<l control methods arc proving insuffi1.:ict1t al controlling noxious and 11uisarn:c weeds, we will request the City allow limited use ofhcrbici,k 5.3 TMlLE2 FIRST QUARTERLY MONITOIUNG NOXIOUS AND NU!:ilANCI>: WEEDS Transect Trnnsed Percent Percent Dimensions Arca Cover Cover* Transect (/,ov) __ .l!,Q__ _ ~/04!20J!2L (07116/2009) I ·--~ 10 f;250_ =f ___ 4 _ 0 2 25 X 1025() )7 0 -•------------ 4 50 X 5 250 () -()---II ~--3 ___ -· 25 x _IO-·-~50 t IO ,___ 0 5 1-100x5 500 30 15 --- ----6 25 x l O I 250 ______ 1 _____ ,... ____ 1 __ _ 7 25 X 10 I 250 45 45 TOTAi. 2.000 17 9.5 NOli.:s: "' W'""-'tl 1.:0\IL"T was rr.:ass,.·:-;s1."tl ,,11 July 16, ]0()9, c.luring ma111t4..'mmi.:c w,1rk cc.1nc.lU1.:lt.:ll h1 t:•1nt1~11 WL'CJ~. sf,., square feet Maintenance Concerns Following lhc firsl quarterly muniloring, mainlcnuncc conccms were idcnlitied and recommendations made to tht.:: .1pplicant. Those maintcnanc1..: concerns and corrective actions that we un<lcrstand have hccn lukcn by the applicant. hased on comm,mica1ions with the applicant. are summari,Lxl as follows: .) ;.J,IJ (<II fJ!/;i.f{J J,.U Wf' d1> 21-1-12 IQJ.005 7 ' '·; l'll ;~ : .I •,'I ... :,r~ 5.4 SHANNON &WILSON, INC. 11 During our lirsl quarkrly pcrl(,r·mancc nlonilnring, w~ 11uti.:d small leak:,, aml gaps j11 the tcmpClrary irrigation ."y:·Jcm where pipes did 1wt t.:tm11L'l.'.I fully. It is \Hu· u1ukr.,;larnling that lhc irrigation syslcm has bc<..·n n:p~1ircd. • /\1 ~be time of our baseline mo11itori11g. w1..:~d:,; ,v~rc ,1bumlunt. cspcd:.illy in areas where mukh wus thin or lacking. It is our u11<.h,;rs1anding that since our 111tn1itoring visit. weeds have been cleared lhn.Jl1glwut 1hc hulk:r arc~L 11 At the time or (1ur baseline monitoring, mulch w~1s not prcscnt around the perimeter o/"the stormwutcr pond or north or the Mnpkwood Creek culvert. North of lhc stonnwt1ter pond, hog fuel/mulch had compacted and ihinm.:<l ~im.:e it h,1d bct'n applied the previous year. His our understanding that since our monitoring Vi$it, 4 tn r, inches ot mulch wus applied 1hrnughou1 !he huffcr area 10 help supprc% weeds and retain soil moisture. Wildlife Observations As the site is within ,rn urban environment, co1Tidors and undistt:rbcd c0nncctions to ,vildliic habitat are limited. No wildlife observation!'. were made during our monito:·ing visit. 6.0 CONCLUSIONS Pcrfomrnnce standards for the buffer miligation site <luring the first year of monitoring are based on survival of installed vegetation anJ abundance of weedy species listed by King County ns Non-designated Noxious Weeds nnd Weeds of Concern. The survival of installed vegetation over all sampling plots totaled to 9 \ percent. Therefore, plant survival on site meets lhc performance standard of being greater than 85 percent. Weeds were fairly abundant on the buffer mitigation site during our first qum1erly monitoring and areal cover of species listed by King County as Non-designated Noxious Weeds and Weeds of Concern initially exceeded the performance standard ofno more than 10 percent areal cover_ However, areul cover of weeds was rc-cslinrnted us 9.5 percent ut the time of our follow-up visit, which was conducted while maintenance activities were in progress. We understand that maintenance activities have been complcled since then. removing weeds from the entire buffer area, Due to the recent weed control efforts, the site now meets the performance standard of having no more than 10 percent cover by species listed by King County as Non-desib'Tlatcd Noxious Weeds and Weeds ofCom:ern_ :11.11J11,-1,c1s.1u,11x:,:.wp.'rlr ~1-l·l.:?193-005 8 ... . .., ... ... •'! ... . , SHANNON &WILSON. INC. 7.11 Cl.OSl'IU: The limling.'i and 1,.·0111.Jusinns donnm:ntcd in lhis rrpnrl huvr...· hl'l'll prepared for ~p..:dfh.: applic.itinn lP lllis pnij1..'l..'I. They have h1..-'L"ll <k\'dop, .. :d in ,1 man11cr ,.:~111si:-;tcnl wi1h tlwl kvd of t:arc am! :.-.kill nornwlly cxcrcisr..:d hy memhns (11'th1..: c11virn11Hh:111al si;ic1tcc profession currcnOy pntt.::1 icing under si11 ti lar ct1rn.li1 ions i11 l he <ll'r...·a. ·1·1i..: t.:tH1t.:h1:-;ion . ...; ,11Hl rccmnmcnUations pr~scn!c<.l in th i:i,; n .. ·pnrl arc prltll.'.°ssionnl opinion:; hascd on i 111t·rprc1at i~in u r i11formation cllrrcnt! y avaHabk· to us and made wilhi111hc opcr;1ti{rnctl scopt!, hudgij. and sclicdult.: constn1ints ofth1~ project. No wmT,mty. LXpress or implied. is made. This rcptHi was prepared for the exr.:lusivi: us1..· llfTom rosh.!r and his representatives. We have prepared the dDcumcnt. ··Jmpm1;111t lnfonnalilln t\houl Your Wetland l)clincat,nn/Mitigation Report:· (Appendix !3) to assist you and others in understanding tile use and limitntions of our reports. SHANNON & WILSON, INC. ?31 ... l-~ Brooke Erickson Biologist 8XE:PCJ:DNC/bxc -----·----.. -·-------·-------------------------- 9 ~ ~ ~ ii It ·! ;'ii ' ~ , ::~ i.j ::ii ' ~ .j :~ I~ >,l ;-,~ '·\l '.~ >:j ,i ".~ 1_,~ ··~ :i. ::11 ;'~ ~ ,, ol1 ;' :~ 1-1 ',j ~ I~ lW : ~ Ill HJ Sil SHANNON &WILSON. INC. 8.0 REFl•'.IH:NCES Ot<1k, 21108, Sceon<lary review of tlw revised pcrforina11cc st:md11rds for the impads lo critical <1rcas assnc1atcd with the Ribcrn-Bnlkn Short Pl:il, LU/\ ll~-J 29: Tcchrncal memorandum prepared 1,y Otak, Kirkl,md, Wnsh., :l 103.1, for i\ndrca Pelt.cl, City or Renton, March 14. Shnnnon & Wilson. Inc., 2007, Funner Ribera l3alko short-plat property final wetland and stream mitigation plan: Report prepared by Shnnnon & Wilson. Inc .. Seattle, Wash., 2 I· I -12 193-004, t,,,. Tom foster, Fou1th Avenue i\ss,,ciatcs, Scatt le, Wash .. March 27. Shannon & Wilson. lac., 2008a. Revised pcrfom1ancc monitoring success criteria for the fonncr Ribera Balko short plat property: Letter lrom Shannon & Wilson, Inc., Seattle, Wash., 21-1-12 193-0~. to Andren Petzel, City of Renton, Renton, Wnsh., January 15. Shannon & Wilson, lnc,, 2008b, Former Ribera Balko short-plat property wetland and stream buffer mitigation baseline performance monitoring report: Report prepared by Shannon & Wilson, Inc., Seattle, Wash., 21-1-12193-004, for Tom Foster, FL•urth Avenue Associates, Scuttle, Wash., September 2. Shannon & Wilson, Inc., 2008e, Wetland and stream buffer mitigation installation, fom1er Ribera Balko short pint property: Letter from Shannon & Wilson, Inc., Sealllc, Wash., 2 l ·l ·12193-004, to Roca le Timmons, City of Renton, Renton, Wash., December 29. 2t-l-t21Q).005 ; {) \. ' ' . ·~ .. ~ .. ~ •. SHANNON &WILSON. INC. APPENDIX A PERFORMANCF. l\lONITORING DATA SHEETS ·Hs ·:.JS :,if. .r1 ' .. .,. _, 1 ::.i ··.1 ·.J \~ ·.·~ " " w ... 0 % ---~ 0 z ii: 0 ... j % 0 , .. ~ " .., ~ w i % w '"' " ) 11) !ll ;!Ii i,i\ S&W No. ,-J-t-! l,.l"l':i-<..J"'""') MONITORING EVENT I ,; qt-, OSSER\IER (?n,-:,k_Z.,-,d.<""' 4 $~G,,-t.,;~ No.of TRANSECTS + (G,lt t<•"'&''-h) No. of PLOTS f Tr.msec.t or Baseline E:".rent This PM Event Ch.:inge ftam Base:11ne. ,. "' <( " " :, " " ,_ .., :, " w "' 0 % ' ii: 0 ... % 0 " Plot Quantlh•1 'f,. Cover1 % NoJCiousl Qllilnli"'·1 %Cov<?-r2 '"!. Noxtou,~ 1 :,!.~ • I -. ,, ,,.,., µ •/ •. 2 'e>"' "L<J -z_e, JLl...,.,i r~·1v 3 '2.z_ -1./ -~ ~ 1,<!I· IO •t. -· • 'Z. '2_ ,?;,: q; "l.. I l·/-., 0 i. 5 I <::> t,.//A.¥ -::i-r-J/Alf-. "'" 7. • ~ .. .;,,, --J., s '-I X 1 ,-:;,. "i,'l J-:/-1 •. (, <., '57 -;. 8 -------- 9 --· --- 10 --~ -- TOTALS I ',<) . ,b,.:,4 -13<-)~'1-% /+•!. J-or dC!lailE"d PE-rtom1ance monitoring fes,:.iUs, please refc1 to \he individual !ransecl/plol outa sh~! ' Quantity is: of only ins!atled wo.xty planls. 1 "I. Cover ,ndudes ,nslae!ed weedy and desiral)le volunlcoi plan1s. "t. Su.viva!• '%. Cove? Si.t: .... .J:!,,__ q ', 'I. +-q "/, \o c;-•1,Jf + Z.c'Z ,q /, 1 • +23% ~,: Iv/A :+, r. z.o,: I c,:,•t. ~ IO~b"i --~ --- Cf I_ ~1. + "1-'I. '% No,:ious includes; noxjous weeds and lhose species spoc1fic.31J~ called cul ff'! the suo:.ess cri1ena {e.g., Him.a.tayan bl;111:J,;berr1J ~ % SuMval iS c! ,e1a1ivo eoJculaLmn based on tho 01ig:na! number or p1.:,n1s lnslalled within the transcc.VDIOI to lhose srn1 living % NoxlOU$3 -~ -~> -_ _,,, --7 --= --- A) SUCCESS CRJrERIA: ~ . • M;','\,i\\.""'"' ,aS'% s ... -r-...,\j...,\ o'? ... ,~ • .,!Le.J \J~c..ht.~ -M&(, c.oJ"'\ ,..., ..._+ 1 I 1o t. !-/01, C•vV "f f)\,,~:t·"s l,>hJ..I\~ r.Jv<-1~~.,lµ.f-t_.Wc.t:J} \~S ,.f'~<lt""'--~(.~f'~ :;or;,./t1 , ~JPF--9P'~7~/"~.J'".V~~.&"'J"~,'~ V--r«T' / 1:1) GENfRAL VEGETATION VIGOR/HEAL n-t: I C) WETLAND I-IYOROLOGY: J tJ IA. O} NOXIOUS/NUISANCE WEED CONCER:NS: IJuk, .~ • ..o .. J ,., rv" ... ~ ~ \.~; .... r~0,.~l :r ~L, -I.Jul; "-"" -L~/Li ·• jV.,,r-h .. ~c~-t: .... \,._;.r~ I ti,,"'"', L • .t to~ff<r E) WILDLIFI: OBSERVATIONS {DIRECT ANO INDIRECT); i,;,,...._ F) MAINTENN.ICE CONCERNS: J,~ )".)., ;., '' I'''"' l,ai.s J11·1: I. ~7dc-I V --:-;1,-............ ~r .... ·-r..,., G) OTHER: 1"1,,\oL t •• L. '') ,, +I,',.._ C\ h1<,l\l.J .,n..~ l Jv/ '7 -11·/uL~ ,, fl' J."'. t ,/-J,,.o,<l'f., ' .,., ~· . O' Q 0 0 1-;: ..: I 't5 ~'~ ; ,, • .. ·Cl · ..• ;I . JI .. , .-, " " " ,, .. --+ ---·-j I i ----=l-' L .i~,;...\:,....,: me~< ,4.,..)'' -,<' -7,..z_•(. f,. i',I ,~,. -.,__ '-~" U.1~~~ (,tt,i ... 1-'·f·t~ 0 0 t/, ... 1·,. ~':'. \ ' 'l:_.,.I,• (.~....,\···-~ri,..._ \· I 1-· I I ,--~· ' + / 1 -I , I r I .• , l I _., ,/ .g,. ' . WF.1'.<, · b,,,, .... II, .,.it..._ .l:.;, -· ., ., . ' ., ., Al -iii .. ;, ..... if ,-;-, i!, "~ ,. ;~ I . ~": (.;.. & ,. -.-~t J ~ ~ " ~ ~ , ~ < 'i' ' < )?I . i ~ ~ ~ 2 • • ~ ~ :: z .! 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I I (' IMPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION AND/OR STREAM CLASSIFICATION REPORT A WETLAND/STREAM REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. \\'l"ll:inJ ddiul·a1io11 n1i1igarnm mid ~tr\·;,1m d:1,s1lic,11i,..\11 r ... ·p1..;r1:,; ;n,._· h;i.~nl 1>11 :r uniqw.: :-..:-1 ,,f pn•.in:t-sp ... ·cili(· frinor:-:. Tho.:~(· typii.:ally indud,: the g.:n~ral n<Huri.~ c•flh..:-pn,jl.'1.:1 and prnp1,:rty irm1kcd. it:-. :-iz1..·. ;rnJ its t.:nntigut.11i,1n: hi:-h,rit.::11 u:-1.· ;1nJ pr:u:tict": 1hc location (1f the prnj,xt mt 1h1..· sih: anJ it:-: \lri1.:niutit1n; ~nJ thL' lcvd of aJditi\1n;1I rlsk ll10: ..:!1..::1:1 ;1~sumo..·1..I hy ,·ir1u,: ~,f !imil.ilil~n~ impo~c:J up()n 1hl· c-xpkir~!lnry pr1.)grJm. The iuri:--dicnnn f,f :my pi1rt1,;u!ar \\"\:ll,11iJ ':-11"1.',llll i-.; di.."tcrmir1ctl h~' ihl' rq.;.\ll;1ll~::-y authority{s} issuing. 1hc p1..•nni1(::). A~ a n.·sult. one-t)f mN..: <l!!-1,.'JKit·:,; \viii han.• jnri~Jidi(.HI (in·r a p;,irtKu!.u \\"l'll:md 1)r .,trcam with snml!tim.::-,:onfo~ing cq;ul..itii11;.:--. Ir is nt..:Cl'!'>sary !11 iiw<il VI..' :! l·ni1.:-ollan1 wh .... , umlcrswmJ~ wh1d1 J._12\'."llL~ ( ~) iws: JUn:-JJ,.'lillJl ll\·cr ;1 p,inin1l:1r lli\:'i\Jnd ":-lrcam :1ud what 1hc-ug~n..-y(;,;) p1.:rm1Hin~ n:,1uir('lllt..'H1:--arc li:1r 1h;11 Wl.:'li•mJ "tr1..·am. l<1 kip r"i?du,._-,_. 1)f an,i\1 p11lL'mi:1l co:-1ly probli;"m-.;, have 1h1.: t·n•ls:1111:mt lli.:l1.·rmin~ lww :my 1:u.:lt1r:; or r .... ·gul,11i<ms (which rm1 Lhangc :,:ubs1..·1.;ucu1 l1.l thL· rl.'pl1nJ may :1m.·Lt thL· rcc(ltnJ1ll'nJa1ilm~. .. ff the size ,'"Ir 1.·1>nligur.i1in111.1f dil' pn1pl1s1.•J prn_jc..:i ts alh:ro...·J. • if lht lnc.itilm nr llficnt,1tit~n 11/" the rwpn:-:cJ prn.11.·(l i:,: n1l1ditkd . • ff thl"f\; IS ,l ;;h.111g_,: nf lHVllt.T:O:lHp. > hir :1pplk,ui.;1n to ,111 :.idj;11..·t·nt sit1.· • Fu!" i.:011:::trudion al an <ld.it1ci.:n1 silo...' t>T <•lJ :0-1\L'. • Folk1wing [k'"lnds. l'<1rlh1.1u.1kcs. 11r ,llh1.·r ac1:-11!" 11;rnrn,_·. \\"ctlamL..;trram 1.·11ns11il~mts l'.:,nnt)l :1..:o...·q11 r,:spL111~1b1hry for pr1.)bkm:s that rn:.i~· dr."\L"k•p 1f lhl'Y :lr1.· lltll \"\1n:-ul11:d uflo.:r fac1nrs l"1•nsi<kn..:d in th\'."ir n:p11rts h1WI.'" d1a111,;1..·d Thcrdi1r1.·. if i ... incrnuho...·nt up1•n ~-1.•ll l\l llt•tify y,•ur t"1111~ult,U1l ,1!":111y f,11,,.·tc,r~ 1ha1 111.1~· li;we d1.-1ng1.'l~ pnt1r tn :-obm1s:-ll1n of 1H1r fin:il r1..·p,1n. WcilanJ bounJaries idl!nhlkd ;111d . ..;11·,.·:im i..:l;1s'sili,.·.1!nin . .,; mad .. ~ hy Sh:1n111•11 & \\'tb11H :1rL· ..:,111:-:11.kn.·o...1 prdimiu.1ry \lnlil ,·:diJ~1ti:J b~ 1lw l!.S. 1\rmy (.\1rr,.-: pf l:ngml"l"rs lC11rp:-} :inti ,ir 11\e h,i::1! _iurisJi.:t11.HUl aJ,!.i.:11<.:~. \';1\i(l,11t,,n t,y thc ro...·~ula1ing ,igl'IW_\(S) prl1\·iJe:-: n \"t..'nilit:atit111, u:-:u:1lly ,Hillen. 1h:,1 1h..: w1.·tl~md l1 1'll11dtml':S \,...rifo .. ·d ,m..: 1h1.• h11unil:mcs 1h:11 "ill I,,_-,.,...~ul:ito...·d hy lhl' ag\.'1k·y{:,;} uu1il a ,p1..•dlinl d;lll.·. (lf until tl11..· rq:_ubt11.•11.-: ;ir\' im1d11ini. ;.111d th.:il 1hc str.:;im ha.~ lw\·11 1m1pt·rl:-,'l,1 . ..;:,;illl·J. ( )nl~· 1h1.• ro...•gub1ing. a:;cnl.'y(:.l ,·,m pn,,idL· rhi.~ ..:a11llo...·;11ion. MOST WETLAND/STREAM ''FINDINGS" ARE PROFESSIONAL ESTIMATES. '.iii .. ' l'sph1r;111,111 1tl1.·n1ifi1.·s Wl.:'l\,111d :,,,tf\'tUl\ l.l'lllh1h'll" ill ,111!:i,-d11 1 :--l· P"t111-: \\hl·f1.· ,;1111pk ... ,IT\.' 1.1!..1.·n .1111! \\h1.·111h1.·_,. ,1r1.· tak .... ~11. hm thl.' phy:-icll n11.•an:-(lf (1bt,1i111n;.! d:11<1 pn·.:h11.k iho...· .... l..-11.·n11in;1t1{•11 nf pn:u:so: ,.__·,1ud111,,n,. l \,n:,;l·qtKtlll~. 1h1.• 111ti1rm,111,,n t1b1ainl.'J i:-:: in11.·ndcJ ri1 hi,; ~11!fii..:i1..'m(~, ;1lTUrat;.· for dl.'.-..;i~n. l~ut 1:-. "llhl1-'\"t "' nH1.Tprt..·1;111\•n .·\\lditi1 111:dly. 1!:11,1 d1..·n-,1.-d 1hr\'ll!!h ~:11111,!ing: ~mJ sub~,·qu-..·nt 1.-,b11 r;.1t,1ry 11.'.,;lm_µ .1n· 1,,• . ..;1r:1pt1l;11..:d h~· lhl: t'\1 \l~tdl:1111 ,\·!111 tlh·n Tl."mkr..; ,111 ,11'itU('ll ;1l~,·u1 ,,, l'r:11! ,:1•1hh,il1n:s. th1.• iikdy r1.',tl'Lil1n 111 pnipp~~·J c1,nsll11l."t1t1n :Kll\·i1; .• ,nd ,,r .1ppn•pn,11~· ,k:;1~11 hl·n und.:r ,1pt111ul i.:11\·mnsi.mco...·:s .. ll"lll<il ,:lmJitet,n~ m.1_,. J1ffa frt~1l1 llhi;--,,.' 1ht1U'.!hl 111 t·:i..i~t bt·L.:;111:-,· n11 l"t111.,td1an1. 11,1 rn;ut<.·r h,n, tJU;1hl'1\·,!. and m, l"'-pl,1r:1t11 111 pr1.1:,:r..m. n,• m;l\1,·r h,n, o...·t1111prd1cn:,:i,·1.•. 1.·an r,...,c;d whal [~ hidden h~·1.·.irtb. rl1d,. and 111110...· ,'-\1 lh1n).'. -..';HJ lit..· rJ,,111.· \p prn,:m lhl' un,11Lt11.:1p:1t-..·lL hul ,1q,:; ,·,m h1..• t.1l,.,._.11 Lf1 hdp fl'dllt:t• lhl'ir unp,10...·1~ l·\1r ;hi:-rl'<1~11u. 11111:<.I 1,,·..:p1.·n1..'11l·cd, "' 111..·1~'. 1'1.'lam lhl·1f -..·,.,11-..ul1· nl::-tlm 1u.l_.!h th~· t:,111..;1n1,·1i1111 ,•r Wt'll:rnd mlli:! .. t11 ,11 ::.lrl'J.lll d,1:,;:-ilit·.1111,n ~1:l~l-1,1 iJ1..·111ll~· ,·;irum·,·:-. h, ,:,,ndui.:I ;1,ld1111111;ll o...·\stll!,tlh'll".> ih,H 111;1~ hi.'. ll\'\'~kd. :111\I 1,~ 11:·,..·i,mm~'n.tl :,;1\lu1i 1~ns 11, rn•l•k111.s ,·1i ... ·1,w1ll·rn! 1,11 s:IL·. l'.1;!•' I ,•I ." WETLAND/STREAM CONDITIONS CAN CHANGE. Si11t'...: tl;llural sv~1~1H:-. ;lft' dvo.i11w,; .sv.s1c1itS ;ifli..•1.:t~ll bv h,1lh na1urai 1.1n1i..:1::-."'-'" ;111d ln1m;1Jt •Klivitit·.s. d1:tll':.'t,::-111 \\rtl::nd b11und.iricti :inti :-:trl·am t'on:lni,111.-; may hL' ,._.:-;pl'cl~·d 1'111.:·rdiirt·. d...:.h1watt•d \\'l'tl,11;,I h,1u11d;uit·:,,: and .slrL·:1111 da~:-1fo.\1\111;1s l'amwl n:111t1m \·;!ltd li',r an !n<.kli11i1,._· p..:rinJ ur lime. Tlii..· (.'1irp.s 1ypi1.:;11ly n.:t,:11i;11iZL':,; th..,· ,;:1lidit~· uf wc1b11d d,:hm.-;tc1on:-ft,r a 1w1wJ uf li\"l' y ... ·t1rs a1"11.:r c,,111plc:1itlll S(lO\<..' 1-'llY :1nJ L',lllllly il_f.t'lll'il..'., h.'l"(l,!!.111/.l' llll· \\1!id1ly llf \\\:t!aml 1h:lin1.·;uio11s /i.ir ;L 1i1.:nod ,1( j\\"p )'L';1r.... rr:1 pl.'ri1 1J or y..:·ars haw pa:-.s..:'J .sine ... • the Wl'tinmJ::-m.•:1111 rt'p<1r1 1v;1,.; ,.:ompk·tcd. thi.: owu1:r ):; ;1dvisL!d w ban: th1.· nm:•a1l1anl 1'\.·c~aminL' 1hc m:1lanJ,s1n:am tl11.ktcrmin1.· if 1hc r.::b:::-;irii.:,11ion i:,. .;till Jt:Tural:.'. (\)nsrrut.:!Hlll L1pcruuo11s a1 ,,r ;1tlJ.tr.::l'lli w thL' sit,: ,md 11;11ural L'\L-'llL" ,-..udt a~ ll1111ds, L'ar1hqu;1k,:s. or waler Jh:crn,ui11n~: may abo ,1IL.:1.:t conJicions and. lhu::. lhl.' 1.."(\ntmuing ,:JCl'IXlcy 0f thL· wi.:l lunJ, :-tn:am rL·port Thi: c\1n::nlt~m\ :-hnuhl t'le k1.:r1 appri~.:d td any sti-:h C\'Cnts ;md sh1n1IJ bi.: (011:-:ull\.'d h) J1..·1L•rrni11..: if ;1Jditnm.1l L'\ .ll11;1tin11 t:-,. !l1,:1..·1.·.,'.':1r:,-·. THE WETLAND/STREAM REPORT IS SUBJECT TO MISINTERPRETATION. : . .fl Cosily prc1ht,:1us Ci.Ill rn:cur wh1.·t1 plan:-arc di.:1..·d,,p,.:d hnsL·<I un 111isint1..·1-prC't:11i<1n (1r ::i w,:tlitnd.·::tri:am r1 pML T,-, hdp a, 1.1id the:,;r;- :;-probh.•m.~. 1h.:-nmsull:mi ::ho1ulJ he rL'tarnci.{ Hl \n1rk with ud11.·r ;tpprnpn:.i11: pr,1ll':-.:,il1n:1l:-111 t'xpl.ii11 rd,·v:.int \\-\.'tl:.int.l. s1r1.·;1m, ~t..'t1k1g1L'i1!. ,ind 1..Hhcr rinding.,. and 10 n.:,·it..'\\' the ~1Lll'llu;1..:~· \Ir pl.'.lns ,iml ..:pn.: i ll-:ati(1ns reb1i,·t· to th1::-:c is:-:lll':,;. :~ j -·~ ··~ DATA FORMS SHOULD NOT BE SEPARATED FROM THE REPORT. Final d.al:i J(1rm., arc dewl('lp~d by 1hc L"On.,ult:1111 b:1.-:~J 1'1'1 in11..·1prt'liH!o11 1·,f !i-dd ::hcc1:-fassvn1hk-J by sit,.' r~·rst1m1d) ;md l:1b~1r:itoty cvalu~tion of fidd sampk:-. Only liual <l;,11.1 hJrms ;;u~1vm;:1rily an: \nt:ludec.J lH a fl'port These data funn:-: sl:01.JIJ 11\)L t111Jcr ,iny ,.;lr<.:u111:-;tarn.:c.~. ht d1,1wn for i11i.:h1::;i1111 in t11h ... ·r dr:iwint,;:-: ho..·,._·;msL' dr,1llL'r-.; m;1y L'\1m1nit ...:1T1ns l,r 11111i:-sit"lns in lhl' tr:m::t'c, procc~s . .\ltlw,ugh phoingmphic r.:,pwlluction diininatt:":,; thi~ prt1!~k·n1. n Jtw:s. 1H11hmg. ln rL·du,:~ ,b,.. p11:>,,ibiliLy l1r n11~intcrprc1ing th\.' l\•nn:,:;. Wh...:-11 this ui..:cur:-. delay~. d1:<"ru1..:os. ,1mJ un.mhi..:ipa1cd co:-;.ts .1r1.· rr1..'LJLt\!ntlv 1h1.• r,::,.ult. T<1 r .. ·tlw.:e 1111..' Jik;..-lihond tif d:n:i ronn mi~in1L·rpn.:1:uii1n. l·(111trni:h)r.,. 1.•nginCL'rs. ,1ml planners shnuld t,.'-' ~i\"L'll rc:1Jy ai..:t"c:-.,; to till' cnlllpkrc rq)(1rt. J'hos1.' whl1 d(, 11{'1 rrO\·iJt· :-am:h Jt.:L't..'!'-" nrny pnX"L'L·J lHHlt..'r Lh...:-mi:-laki.:n impn's!'<i(m 1h:il :-irnply di.:,..;la11ning rcspc•n:-.1Pility for llli: i!n.:m:u:y 11f 111f(1mMno11 :1h,·:1~·s 11L~11bll·s 1b ... ·m fnim .ltll'll~l:rnr liahility. Prln·iJing tho.:-hcst J\'aibb!i" infom1alion lO 1.:ontra...:tcir.~. L'ntdl1t..'l'r:-::. ;rnd pl.:umi.:rs helps pn:vi.:nl cos:ly pn1hlcm::; ,rnd tht:· ;1<ko.:-rsarial ;1t1i1uJ1.•s 11l;1t ;;_!!gr~1\'i.H~' th1..'m !O .i d, spwpl1rt m11,l!L' .~-~all'. READ RESPONSIBILITY CLAUSES CLOSELY. Jkc;1u:-:1.' ;1 w'"·tkuttl ddin1.'<llil111 . .,:;--...::1m d:is..:i1knrn111 i...: h;1.,;cd l'."11.·11.,i, cly llJl _1udgmc111 anJ 1.1p111i(111. i1 is for kss L'X:J.Cl th;1n ,,1hcr Jc:-.!_gn disciplu11.·:-. J"ltis !>-lluminn h;is rc:,.tdted in wholly t111w,1rr,1nc~·J d:nms hcing 1,,dgcd again~! n,nsulw1,1s ·1t~ hi.'lp prC\\:111 lil1~ pr(lhl..:m. i.:011:sullanl:-ha\"L' £kn:k1p1:d ,t uu111hi.:r \11" ,·lau"l'::: h1r us~· u1 "mtL'll t ran,;miu::ib Tlll':<.t' ...re nnt ..:~ndp;1h1r;,• d~L1:-~:-d1.·..:if u~d 111 fi_,i:,;.L tht.' i.:nn:,;.ulianl':,. h;1hili,it·!', (IJ\h\ )-lllllt'(\ll(' d ... (·: r:1Llll·r. 1h1..·:-:lrl' ddinill\t.' ...:[;111:-... ·:-1ha1 id..::mw\· wli..::r1.' 1h1..' L,1nsuil;ir.l':,. r(':<,p1H1:::ih1l,tici: begin and L·nJ Tl1c1r u"'-' hL"lp., all p;1r1i1.· .. ul\ok._.J rl·1.:,1~ni't.1.; Ihl.'"ir inJi,·:dual rL·:-:p,111::ih1!i1iL·:-: ,111d 1,1h.: .11,pr11pri,11i: 11..:1il1n S\ifftt: L'f th;.•:-1.~ (ll'1initiH' d11us1..·:,. .:n..: likely lo appi.:~r m y1nir 1vpnrt. ;111,J yo11 :1rl· 1.·111.·,•mil~L'd 1,1 r1.•:1d 1h1..·m L·h,:-,.._·]~·. '1\1ur L't'HStt\1;1111 will bi.: pk;1:,;-:d hi ti,·L· full ,mJ frank ;msw .. ·rs ;,, ynur <1u..:~ti,ins. THERE MAY BE OTHER STEPS YOU CAN TAKE TO REDUCE RISK. Yl•ur cPn:-11i1;1n1 \\ ,II hL' pk:1svJ h1 d;:--i.:11;,;s 11thcr 1v .. ·luuqu1.·..:. ,1r ,k~i~n-:,. th.it 1.·.111 bt· ._·rnrh1y1..·d I\• m1ti~:11..: 1lh' ri~h. 1·r Jda:,. s .rnd 1.1 pnn·1d,.: ;1 ~·and~' 1}!";1h..-nml'.H•:,.11\:11 m;sy h,: b1.·11dk1a! tn ~-l1ur i~r,,_1,.'d. '• ' ' (7 Former Ribera Balko Short-plat Prope11y Wetland and Stream Buffer Mitigation Second Quarterly Performance Monitoring Report Renton, Washingt·. September 22, 2009 LUAcZ-/)1 . . SHANNON &WILSON, INC. ,· DfOfECHfflCil.L ,o.J,/"D E>IYIROkMl!Kl1H CQNS'JLTAHTS f~,celkncc·. l111w1a1io11. Scr1ic~. Value. Si11cc I 95.J. Submitted To: Mr. Tom Foster F"our1h Avenue Associates. LLC 6450 Sou!hcenter Boulevard, Suite 106 Seattle, Washington 98188 By: Shannon & Wilson inc lh , ' 400 N 34 Street, Suite 100 Seattle, Washington 98103 21-1-12193-005 SHANNON c, VVILSON. INC. TAlll .E OF CONTENTS Page 1.11 INTROIJl)Cll(J;,; ,\NI> SITI: DFSCRJl'TION., :' ti l'El<,.OR\IN,c I·. Sl·\~IJ.\IWS. ............ -.... --. --. -I .1.0 MO~ITOI\IN(; SCI IUJI :u-:, 4.0 :,,J l:Ti J()l)S, . 511 RESll!TS,, ,. , ).2 5 . .1 ) . ..J No:..;ii 1 1Js ;md Nu:s;11K·.,.: \VL.'1.:ds .. Pl;mt Survi\'.tl and ( 't1\·cr \-faill[l,.'ll:Ull'L' .. \Vildlifr OhsLT\'att(lrl:,,;. !, o ('ONCl.l ISIONS 7.IJ Cl.OSI 'lff ~.O RUTlff\;( ES .. T,\llLES Sct.:uml ()uiirti.:r!y Monitoring N(l.\i~ius and ~usiaJ1L"I..' \Vi...·1.:d;,;_ Sc .... ·11ntl Quarlt.:rly .\fonltnring Tran::.H .. '(l Sampling Result~ ... FIGURES ::-;ill' Vii..·i111ly /\'lap ~ S\.'i.:ond ()uartl.'rly .'vlonitoring M~1p .1 Sl..'t..:~md ()u;.1rh:-rly ;\1onitoring Phot11points APPENDICES 1\ Pi..:rl(irma,11.:\ . .' .\rli 1nitnri ng: Dal a Shl't:ts B lmpnrtant tnfonnati~111 Ah1.ml Ynur \V1..'llaml Dl'l1n ... \1tlnn :'v{itigatiun :111J ·nr Srn:-im ('J;1ssi t[,t,;al ion Rq~nrl ': I ) .·['II • <,\ ~: ." ,I, . , 11.-l .... ] ' ... ····· - ........... J . ... -1 .. ,.--1 ....... '.' , ..... (1 '""""' """"·· 7 .. ,. 7 , .. 7 . .......... '1) . ,, ....... J . ....... S 21-1-121\n.oo:,; SHANNON &WILSON. INC. FoR~IJ<:R RlllFR,\ ll.\!.l<O SIIOIH-1'!.AT PROPElffY \VETI .,\NO ,\NI> STRF.\\l BUFFUl. MITl(;,,TION SH'OND Ql',\lHJ<:RI.Y f'EHFOIHL\NCE i\lONl'rORJNC l{EPOHT REN!ON, \V\Slll"<Gl'O:-. 1.0 INTRODll(TION ..\NO SITE DESCIHPTION This report prt..:si,,.'.'nl~ ihc ti11dings of Shannon & \\.'ibon. Inc. ·s (Sh;111non & \Vil.·-aH1·s) second quartt..:rly pl'r!"onn~ult.:l' mvniltiring n!' thl' ,n:l\,11H.I ~u1d ~;tn:;1111 lm!li..T mit1galio11 on 1'1e /~)J'lllLT R1hlT<1 lk1lkt, ~horl-pl;,t property. Th.__· purpn:-:.c n!'tlH..· pcrfmm:111c!..' 1nlini1ori11g is lt1 asSt'SS the hunl..T mitig:atit111 to provide a ha:-:is l~1r dtknninin~ ,,·hl·lhcr lhi.: g.\1;1J-.: ol'tllc mitig;ition plan ;in: hl'ing LllCI ;md. ifOl'C..:C.'iS,lry. h\ H.lc11tify ;1d:1rli\'t. .. ' l>r n .. 'Jllt,:\ht,I ;:cti,,llS lo L'!lSlll"I..' lha1 (flL' gll<lb of the rrn1ig.,1tio11 ~ire achici.1,.:d. Tl11..· !ixtrn.:r ll1her:; ih1Bw sliort·pl;it prii11\:ny. hcn.:.ilh:r rl·!LTrcd {\) a." ··ihi..: prop,..Tty:· is 1.:U1T1...'ntiy .tn llntkvl'iopl'd. ··f .''-sh;1pt·d pared [ /<-".int! ( ·~111n1y P:ir, .. :d t'--\\. :-; I X2 I 000~0) ht)ll!Hkd hy NE -~1hStrcet w !hl: north ;11HI hy n.·s1clc11li:d and ....:u11rn11..-ri:ial-usc pr,.11\1,.'rlks l)Jl the ~:.isl. wi...-st. and :-.ot!th in R1.:nru11. \Vasbingtnn (Figure J) I hi..' pn,pl'tly i, apprn:\im~rkl~· S_,.)!\ 1.1t • .:rcs and h1c,tkd wiihin lhe ~\V '.·.; ofS;.:-ction 15, Tvw:l,·hip ~_-; :'<t)f'lh. Rall!!l.') E;1:-,;t. '\fapk\Vt.-{1d C'rl.-ek l'ntcrs (he site lhnnigh a t.'Llh"i.:rl :.1t llil..' wl.·st.:rn b\1rdcr l)( !ill; prtipl'I ;:-,1 and i...'\.ils !he property 1hrough the rnidtlk ,.)f till..' st.iuthern honk,· ( [·'igun.: 2). f n :?0,)(>. Shannnn & \Vilson dl'lincatcd twn wetlands on thl"'. propl..'11y. On:..: \Vdland straddles ,1 pnrtion <:i' ~lc1pk,vood Crl·t.:k :1k,11g lhl.' wc~tcrn pnl1ion 11f thl.' pnip1.:rly. :\ Sl't:ond. isolall.'d wdl:rnd \va:~ di...:line,1k<l ;.ilon_g llll· _..;nu them rortion of the properly. c~1s1 11i' the poinl al w\iid1 \-h1pkwond ( ·rl'<..:k t:xits 11K' :,;it\.·. Mitigation wa:-:. approved hy the ( 'i ty of R l'llhH1 (1 lK ( 'ity) to l'\HHpi.:"n:-::lll' Ji tr ;1pprnxirn:.1tc·Jy 5.() J ~ StJUart: fee( (~t) -n/'unavoidah),; impSll.'(S lo the W..;ll~!1ld 1SlfC;J.lll hulfi:r as U n.::,;u\t of a prnp1.1seJ ;.;0111mcrcialir,; . ..;ickntial ckvdopmuil. The ap11ro\·e-c.J r:inc.il \VdlanJ and S!rc~1111 Bur!i:r Mitigation Pian prcparc1J by Shannon & \V1ls,m. Jalcd March 27. ~007 (Sh~rnnrn1 8.:. \.Vilstiri, 2007 ), was dc:,igncd to esl<.1hl 1.sh a natl\'(' pl~mt l'ornrnuni I y t)11ie-;il or the :-.lllTOlHHling umJ isturbi.:d buffer thwugh buffer restoration f 5,912 sl). hufk-r n:pl;.1ccml.'.:11t c'.1J l] s!). 1111d bulkr cnhan•:cment I 16.ll I] sl). 1 f ; •1.,; 1~1• I(.'. ,I· .. ,\" p l~,I ,! J. I -I~ I q LO!l:'i J SHANNON & WILSCi\l. INC. 2.0 l'ERFORI\IANCE ST,\:-.D.\HllS Tile linal p.cd(nrn:11H:c -;tandards l\.1r yt::1r Dlh.' (l/U;trti..:rl_v 1111.H1;h1ringl. ~'" :1pprn\-cd hy :Iv.: Ciiy. an· :-;umrnari;,,;d hl·low (( )!ak. ~00~ ,md Shanll\\ll & \Vi Ison. 200:-<i: • • ' • .,\ rnini1nuin ot" ~.5 ptrl'!.:111 st1r\'ivc1I of 111:,;tallcd ,\nndy \•:!:;i.:latio11 during any quarlerly 11wnill)l'ing 1...'H'llL or 111 :1wrc tha;1 20 pcr• .. :1.:nt planl 111orlality ul' in:-.t;!lk<l woody \·cgctat!on for thL' lirsl .'Car within thl' ~'1Hiri...: burrer ;1rca. Nn rn11rc than IO pcn.:t:nt ;1cri:.tl L'<l\'<.T of I tim:ilayan hla1.:khcrry (Nr1h11s discolor), rci.:d can;.'.:·ygrass (/1/ialuri.,;, anonlinoceu), Lnglish i1.-y {//('dt·n1 heh\}, ~111d spcci<.:s li;tl'd by King Cou111y ~1~; Nnn-dcsigntitcd No.,iou!-= \V1.xds ;~:~1.I \\·l.'cd:--<11'( \,nu.:rn thrnuglv-1ut the eniin: hurter ill"l'il. At !he end \lflllL' !'ir:,-1 y1.:ar. ;J WL'll;ind biol(1gi:--t \\·ill dckrrnirn.: lh1.: ("dl'lll nfplant mortality that tnok rlacc Juring tli;:il yc:ir hy uwk.ing J ct1mpr1...·ncn"1,·c pl;mt counl of the cntirl' htilh.•r arL·~1. 1\.1! plant mortalities must lw 1Tpla1.:1...·d durin1! tlll· foll ur wintt:r rolh)\vin~ lhc tlrsl y, .. :ar ,llkr pl~Hli in:,:t~ll:.ilitlfl. If plant mortality Is grL'<.1tcr lhan l '.' pt:n:L'Lll tl,lhnving lhc compn .. hu1:-.in.· plant l'PUnl. ~1ppr(1pr1t1ll' u1rrccti,·c rncasures will hL' t~1kcn lo fl'duci...' lhl' potcrnial l{ir furlher dic·back. Vofc• !ltut "U!:.(C.E'.1!_{__1jJ,j~1J.!..(.\lji_J.·i~E.!" is illfc11dcd Jo rc:f/t'cf the 11cr, 'l'llhtgc a(li,·ing free and shruh seccin inifi{l/~1-' i11.H11ll(1d mid(!}/\" .rnhsc'(JIH'JJJ pla11, l't'JJ/(l('('JJl('lli\" wtllri11 (/J(' ff[l1"<'5L'IIJ0/(1"t' sumeling lrum·t'cfs flfOf inc lr1di11g rc~n,itcd S/Jt'('ics) rdu1i1·e 10 ,he numh('I" ''.I fl'('(' and shruh spcci('.\' recorded dur·mg the hns,•li11(' mo11i1,wi11g ,TL'II{. 1\t the n:quc:-:1 llfthc Ci1y .. :1 ;s;lnrrnwatc.:r pund l~1ndscupi11g rlan was prcpi.trl·d ,md suhmiHcd in the Fi n~1l 'vV ctl:.iml anti Strc .. Hn 13utlCr tv1 itigalion PJ~1t1. i l(lWl·,·cr. I ill' sttinnwatcr !)(Hld [anc..lsc1pi11g is 11ol suhji.:L'l h1 th~ pL'rf(1mrnncc stnndmds l'f pt..•rfnnnance m1111i101 ing ,·c-.1u!r{'!T1cnts withrn till' ~lL1fli..-r 111i1ig:ition phm. J.O ~lONITORING SCHEDULE Tht: ('ily n:quin .. ·s pcd(1nnm1t:c 111011itoring ofth1.: huffer mitig:1ti(1n sitL' l"Pr a pl'ri(id ul'ti,·c ~-cnr.-.;. Th,.; mlmitonng. program rt ms1sh or u hasci inc rep on fnl lowed hy qtwrl~rl y monihiring \:\·cnts rn1d reports during till' lirst y,.:ar and then unnua[ly lh..:-n.:-alh:r. /\tkr i..;ia1;h 111onih11ingl'H.'nl. a pcd/)rmar1ci..;i monitoring repn11 will he prcp:irc<l tn Uo...:unh.=11t th..: ~kgJL'C ~)r suu ;,...SS or foilurc in !he buffrr mitig.alitin :-;1k.· and to ick·ntiry mlapliH:. l"L'llh.'dial actinn:,: {l1 t..·ns1.1r1.· that !he.: gnals nfthc hutli:r m1tig:1lin1: plan are achil'\·cd. • ! I I. 1•, L '"'' IS.' •1,.,. ,_ "I' 11.1 ' I _J SHANNON & WILSON. ING f'!lc :,.L·hcduk !lir pL'rl(nrn;ll)L'l' 111uoi1urinµ.1:\1'llh ts prnvidcd bL'lt>W. !Ju•.; tn ;J dcl;ty in li11;d :.1ppnwal nfthl' mitit!,aliPt111hLdJ;1lin11. 1h!-, llHitlilofli\!:.~ :-.ch •. :dul,.: \\ :is ,1djll"~tcd from lhl' scllcduk proposl'd in ow 13asdinl' l\:rli\nH;lrh.:c \,1lrnilnnn.;! Hqitirt. • • • • Bn:-di11e {1.:u1r,pk·1 .... d July l (1 . ..:!OOS) Year Orn:. Fit~I <)uarkr .•\pril 200<) (1..i.1mpkl1..·d '.\1ay-'. 200 1)) )\:;,ir Orn.:, S1..·cond ()U<tri.1..'r July ~fl()') ("_·ornpktcd :\u;u..;1 ~<1. :~Wl 1)) Year On...:. Third ()uarll'f Ut.:toher :io(Jt) ra YL"<H Om:. [(1urth Quurtcr fk.:c111h1..·r 20li9 c '(i...:ar·l\vu Fall ~010 • Ye.Jt· Th,,·e F,tll 21111 ' • Y l'<ir Fnur Y c;:ir 1:i n: r::,11 201 ~ Fall 2111] -LO ;\JETIIODS !"he second quarkrl;i1 nrnnitnnng \\·;i:,.; ,.\\it•\tt(lcd ~,11 .-\ugu..;t 2(,. ~00'). t11 n..:cnrd (nndi\i(1ns or th1..: mi1ig:1tion area. V!..'.g..:-tati-...c moni1nri11g \\ as i.:nnduch:d using SI.!\ rn bell lransc,.;t _-.;;.unpting plots (Figun.: ~). Plant :,;ur\"iva! :111d l...'011dil1<H1 (e.g.,. \'igi.lf'tius. living.. ,tri.:s.,rd. d...:ad) orin~t..ilkd wnody n:gL'tat ion. pcrr•,:tlt :icri;1l c1)\·L'r of i 11:~t:d kd ~!nd d, .. :si r,1 hk nali n: rC"(!"llllL'd woody H'g::tat ion. and pcrr~·i.:nt ;.n.·rfol c1.>vcr nfn~lXi(H1s :,ml 11uisu111.·L' Wl.:...;-d-. were ri...·ctln.lcd. lvfai11h.:-na11LL' L'1)J1(r...'ms ;.ind other conditipns tlwt may be dcrnmi.:ntal In the SllC..:-1.·:,;:,; uf th\.' rnitigaiino and dirr..:-d or irnlin:d wildlife ohsc.:rvai.ion:.: were rcn,rdcd li.,r lhc bufkr m1tigatiu11 sill.'. Phnlographs were taken at the [i.1ur photopPint lor...·,.ttions 1.'.'slahli.shi:rl dllrlng. lllc h,1~dit11.: pcrlC.inn,ulL'C nwnih.1ring. (Figure 3). A;:ipcndix. A cn11(tlins pt:rfonnanr.:c monit<_iring flcl<I data :,.J1cc1. .... Tht.: sc\·cn b...:li 1rnnscd sampling plot..., wcrc ,~sl:ihli!•:IH..·d during om basdinc monitoring. anJ <irL mar~t:d wilh green n,-i:tal ft..:111.:-c :-,:Jak1.·s. A tzipt.· ruk was :-:panned ~KTti:,;~ the tup 01 the metal slakes. forming onc a.-..:is oflhc !ran-.;r...·d {y-ax1:--}. A 5-fo(it-lnng 1111.::J.suring stic.:k, markL'd with 1cnths ora foot. w,_1s hl..!l<l pcrp~ndi~tilar 1(1 th~ tap1.: ruk w !'orm lhc sr1.·ond ::rxis {x-axis}. Sampling w~i~ (omlur...·ti...·d hy w,1lh:.ing p;,mdkl !!! rhc lapc nik and holding the 111castmng !-ilich:. levci \\·ith onr..: l'ntl i1ush with the tnpc rnk. \Vh1..·11 \Voody vcgr...·tnio11 W;ls • • .-ncollnlr...:n.xl. thi.; width tif the rbi1t along !hr...· x-axis and y-,1.\is was rt.·r...:unkd. l\.:n:cnt ~11...-rial t.:o\·t.·r (11" in;-;1ai1t.'<.l and dcsirahk native rr..:r...-ruih:d woody \'l..'!,!L'lalion was ,:aku)ntcd hy mulliplyin~ the n-idth nflhL' pl.mt along. tlK' x-axis b~ the kn!!,th of lh1: pl.mt ;don.!! lhr..: :·•n is. Pt.:rc~nl :--un·i ,·,ii \\ ,is c.iku lah..:d by· L·nmpar'.ng till' n1.11nh1.·r n r su1Yi \ in~ mst,ilkd plants oh served during tin.' sc1:1'11d qtiartcrly nwnitoring, t11 thl-' 1lu111bt.:r 1irinstalh:cl pl:1111s t,hscrnxi during thr : I I I . I••: 1 ~I\ IJ .. ' .:.·1 • ·,, \' tl.l J SHANNON & WILSON. INC b~1s1 .. :li11l' nw11i1nn'.1g. Only (he Cull1rn:in~ pl;ml.s; '.'iJll'lilli.:d witllin 11,:..:" appnlVl'd planting pl~111 \.\'l'tC used tu d1..'hT11111w pia11l <.;tir\'iv:1I: lnd1;rn plu111 (()(·wle'J'iu nTo.,i/urmis). Lewis' nl{l...:k nr:rngc ( /1hi/adr·l11l11fs In, i.\·ii). l'all Orl'gungJapr..: (,\{ulio:1iu '"/lfiloli1111!), Noolka ro:,;c (Nosu makww). ,ind l)oug\:is lir {/\<"udo1.1·11g.1 11t<'lt:ic'1·ii}. \\'hen.: tree canopy was L"Jll'Ul!llll'n:c..1. ,igni 1i ... ·,ml \ , .. :ni:..::r\ \\·i(lii11 the lr~msct.:I \Vl'rt: n.:l'Prlkd 111 dctlnL' !ht.: art"a nrL·..11tnpy c1l\'L·r !(ir vcgl'li.1tio11. Percent a...:rial i..:11q:r Dflinbacl:nu~ ~pt.-cl ... ·s wus \.·i:-;ual!y \.'stim:llcd \l\ , .. ;r lhl..' 1ut;1I pl<1t ar-... 'a tu cldcnnillL' th..: :.ihun..Janc<: of llll\.1ous and nuis<HH.:l' \\Ti...·d:-.. 5.11 RESULTS 5.1 '.'io:dous arnl :'\luisalH.'C \Vcr.!dS Dunnµ our lir~! qu:trlcrly 11111n1t~ll"il\g vi~it t..'.nm!uct1.:d l::1rlil·r lh1...;, sunmwr. ~1hu11d,111: w('cds Wl'n .. ' obscn·L·d t)Jlsit...·. \Vccd'i ohSlTve<.i during the pn.:viou;-; 1111111i101 ing. irn:lud,.:d :-;pl'Cil'S lisL!d by King ('1)Ut1ty a:-, Nnn·dL'sig11:1lcd Noxio11s \VL·,~d:,; or \VL·cd:,; (1 /'Cnnl'l'm. stH.:h ,1s H1111alayau hi aL·k hcrry (/(11b11,,· ormc11iucus ) .. fL'Cd L·anurygrat.s ( I ':,aim is unmclimrcl'11 ). Scot·:.: hrnorn ( ( \,·is11s Jcop,1ri11s). C,u1;1da thislll' (Ci1·sit1l!i 1ll'\'c'11sc·). and creeping butl1.:rcup (lfommntl11s r(pn1s). The ~1rpliL·~1nt explained lu us during l}Ur Ol(l1Jill1ring \·isil that intl'n~iu: \\.'Cct! conln1J r.:fli:)rt.s hJ\'L· hcc11 condul.:tcd this :-:umml'r lo rcnH1\'L' \\'l.'L·ds. During iior :--cL·nnd ql1~irtcrly mnnitorin!,! vi:..il. \·cry liltk \\·t.:cd L"c.\·cr was oh:-;Ln·cd thnluglwut nwst t1r1hc ,;ill'. Ba::;cd on c1ur s,unpling tra11:..cc1s. thL-e:..!inwtcd \vc1...·d cm•(T 011:,;it~ is beluw nnL· rcn::L·nl (Tahk I). TABLE I SECOND ()UAHTERLY ~IONITORING NOXIOUS AND NUSlr\NCE WEEDS I Ttanseet Transect .. L Percent Transect Dimensions ~"1-______ Are,q~f)____ .. Cover ~ ·-------·---- I I 25 X J (I ~5(1 I ·-2 2 L 25 X 111 T ~5{) , .1 25x lo 2:-i(I l-2 .. .1 )[J :\ ~ ~:"',U I .()j s J 00 X ::. _::;no . (l.::; I ,, I ~5 :( 10 ~50 I n 7 .25 :< 10 ; 250 t 0 ---· ILJ~OTAI. I >I -_--...,d WL· nhs1..:r,·l'd twl1 ;.1rc:1s 111 lhc nnrthwc~tcrn purtio11 l1fthL' .'>itL' \\liL'J't..' maintl'nan,:c wtnk h~Hl nol hL'Ln 1..·ompklcd at the liml' ur pur moniti.}ring \ 1si1 ;111d wi.'cd:-; wc1y :ihundanL Onl' ~,r Lt11.·sL~ arc.is is !t11..·~1ll'tl r:01 th i!f !hr !\1:ipkw(lnd ( ·n:ck ruivlTl anJ appn\xi111,1tdy 25 fL'L'l ~outh ol°Tr:m:--cct 7. :r 1 1 .';,,1 ,,, .• ii:., ... , "I' 1~.c .. ,i ••. J SHANNON & WILSON. ING lllL· other ,1n:a is l,11.:.ih..·d on t!ic caskm J;i,,:in~ sh}pl' aho\'i.: the 1rd1ut1ry to fvfapkwtind Creek :111d 1.-:i:-.t {11··rrn11sl'l.:l 7. ·1·111...·st" :1rc<1s wc1\.: d{11111n;itnl h~: s ... :,11·s hnHll!I (( ·1·1is,rs .l'l·,11mrim·) und 11 i mal a y,111 bl;hJ.: bi.:rry ( H11hus <1r111cJ1,'dn1s /. B;i:-:t.:d on uur cnm·crs~1lio11 w1H1 ! h._, app 1 i i.:a11L :\..lr. 1·nn1 h1~1t..:r. 1111 Se11kmhi..:r (). ~00 1J. m:tinh .. ·11;1111..·i..: \\·pr~ 1,:,11Hh1,,:11..:d :dh.:r ,1m nwnilonng \'i)•il lus n .. ·nw,·,.:d wi.:cds in ~H.::>c lwo ;in.:as. 5.2 Pl:ult Surdntl and Con•r During our s.co;.:nml qu;.1rt1.:rly monitoring. \\'l' (1hs1.:1YL'<i 1ha1 nwny PCll1 .... · in:-:t:dkd pl;mh wen.: in g.nod !;()TJdilHlll ;md:or 1hrivi11g.. wilh !lhH .. :k nran.~..._, (liliiladd1,l111s /1•1tisii) slK,wing. thl' mo~t noli~·L·.th!1: ~,r11wlh. I lu\\"L:\"LT, pl:ull n10rt;1lit) C."\litn;1ti...:t! during lli1..' SL'COIH.1 qu;1rh:rly 111n11i(\lring h~1..; i !1LTL';_1scd :--in~·c I he hrs! quarter\!"" lllnnilu1 illg. [3.isctl on our s.impling lrilllSLTIS. \\T c:-:li male that th..:: ~L'l..'C1!1d qo:irlcr 11lt)rlaiity rnh: is 27 pi..:n:L·nt {Tahk ~} . .\!l1r1,ditii.::--wt..:rc hi~hc~l in thL' SlH1thcm p,1rtion l1/"1hc sitL'. parlicubrly ~l!lhlllg lhi.: lnd1;1n p!um (Oem/('ria ci'rus:/i>rn:,s) aml 1l1c Dou~Jas fir t /Jx(udo(.rnga mc11::il'sii). "l"ht: i11cn.:;1sc in ll":.c 1n,ir!ality r.itc m;1y be dt1L' lo tl1c hot l<:n1pcralurc . .:; and dry wc;illlcr th:11 occ.:urri:d thi:..: sunmH. .. ·r. dcspilc pl:1111S hL·ing w::1tcrcd as n.:quired. Addilil111ally, :·WlllL' lhc sm;.1Jkr plants may ha\'C 111:1dn::r\cntly hccn n.:moH·d during tile l.'Xh.:nsi\'L' hand wc.:.:di11g 1h,1t uccuncd prior h1 I his m11;•iiori11g ,·1:-;it ;.1:-; St:\L'ral 11f !he :-,.mtdk·r plants vvithin thc :-,.aJ~~pling \f<!ll:-..c1..:h \\"1...:n· 1.1b:--c11t. T,\HLE 2 SECOND QlJAlffERLY \WNJTOHING TRANS UT S,'.~lPLIN(; RESULTS i frnnscct Trnn~cct Dimensions Arca _ Tronsc __ (lx.!"i_ __ L __ ~!l _ 1 _ _ ~'--''-~o I 2so -~ r·· 25x Ill II 250 1 -f-25, ltJ 1 _ 250 -I t 5!1_.x 5 , 250 °' ---JOO x ) ,! 500 L, --=< 1 ,·_-··--.. -2:"1 ... 10 .L . 25 x JO ' bi ~50 .. 2~!1 ff,\!. ;'\Jo1!l"'' Uasclinc Number of I-Percent Nnmbcr of Survivi~g Percent I Aerial __ Plnnts 1 ____ Plnnjs· __ i\:l2rtnli9• I Cover' I -11 t 7 29 17 j ;II} }[} J " 21 " 17 .. 1. 11) -1 j .=:o 14 , l i 17 lo I 150 I !09 =- -l~ 't . . . : ~~ i -I . ' I I ! 21 MI 111 6 27 ' r !._ ' -! 19 6 -- 1.1 14 - 1 :'\wnb,..•r i>r pl;ml-: i11dmlo, "tll~· in~ialkd \ t:~\'l,tl1n11 '-1'1.'\."lfil·d \\ 11hi11 tlu: .1ppr1,u:II J)hmiio;! l'bt• Sn.-I ,,bk I ,,f lh..- l 11.:d \\\ 1;,nd,111d ~m:.1111 llufh:1 \liLi~:1111,a l'h11 (:-ih:u11i,,n f.:. \\·11'",111. ~IIIJ-1 - \'unih1:r 1•1 ,11r,. iun_f! pbnh r., 1h1.· 1111mhl·r 1i( 111,1alkd ,,.·t1.·l.111<1u ,·b,,.n 1·li d1:ri11).' 1!w li1 {l tt11,1rllTh 111,11uti>tm~. ~·v kiJ 111 J.: (k;11' p!,un, ' 11t.·n:..:m ,ll'n;il ,.·01..:r mdudl"'-bt 1th i1i~l:1tl,:d ,·q!,;1;111,,u ;111d 1k: 1r;1l,k T<.:l"l"IUl\'(I 1w1,,Jy ,·1.';:,:1;111,,11. ' /'tTc..:111 .11.-ri.,/ 1.·,1H·r 1~:1-.. 111•1 rL·..:11,d,..,,i 11,r th,: ··,.·nl1;11: .. ·,.·d" h,dkr :1r,:,1 \1h,.·r,.-"nly !A,ushrn !ir ,.,.,~ m,1.dk-<l. ,r .,tp1,irl' k...-t 'I I 1.'J•, I '"" I(.' ,h,., '•'I' lk-l I j SHANNON t,WILS0f\l. INC. Slh.'\.Ys:-; crt\cri:1 r,1r plant sur,·i\·;ll require lhat th<..: o.:il1..· ha\·c 110 more: limn 15 pl•rcen1 nionality duri11~ qu;1r11.:rly Jl\1111il,iri11g t11_· 1H1 mon: than~() pc!\'l'lll mortality !r)r the lirst yc;1r. The ;iduid nwrt;i!ity r;1ll' (pr lllc l'l1!.n.' mitiµa1inn s11e 111ay be dilrcn.:nt J'r\1J11 our :.:amplin!,! 1· ., .,.,.._., cs!1malc 11r ":..7 pcn:cu! ·1 ht.: :1ppr11n.:d 1ni11g.;llin11 plan 1..:nlls li1r a c11111prch1..·nsivc: plan1 L'ou111 ul' the crllirc huffc1 ~ll"l';\ i.ll th(' 'l'lld (Ir )'l·;,r (1n,: l(l 1..h..·tcnnini..· th,: ,:x(clll \lr pla11t morlality that :o~ik pla .... ·c durin~ tile lirs! ~L·ar. We \viii (onducl.:1 co111pn:IK'11:-ivt..' plan! cn11n11l11-; foll ln dden1111H.! i(llw 1110rt~1lly ,.1\c 1(11 ll1l' \\'hok silt.: if meeting the ·,;ucc•.:ss 1 .. :riti..•ria_ 5.J !\1.lintC'nnncc 1-"tdlu\vin.g the lir:-t qu~ir:t:riy ruonit,1ri11g. maink'll(llh.'L' c11nccrns Wl'n: idcn:lli~·d ;n1d rL·commc:1datio11:s mad<.." t11 thL' npplic.1111. Su111111ari;:cd bd1n\· ;irL· 1h<.i:•;e mrn1H~n~1111.:c L'~llll'L'rns (in hold) ,111d ('Offu:tivc adit,n:-; tlwt we llfH..krsland h;n·~ [11:1..·n l:1kt.:n b." thl.! appli(:anl (in ildlics). h:\•,cd Pll ph..;l.•n·;1!i<111:s made during the sc1.;om\ quarl1.:rly 1111irnt11rinµ. nnd-'pr L·1i111111u11ical1l111s with lh;..: ~1pplii..:ant. • • • During our fir!-t qu~u-tcrly performance monitoring. we not<.•d small lcHks und g:1ps in the tcmpornry irrigo1tio11 sy~fl'm ,,Ju,rc pipes did uot connect fully. /lusnf (}Ji COJffc•rsalions 11 ith th(' a1111/inml, 1/1c i1ngutirm .1.nfc11, lias hteu U'poircd 011d is !idf1'.fi111clioni11g. /)11rr11.~ 011r scnmd 1111,11"/cn1· mm1i101·ing ,·islf. 1w /('ak.1· or gt1p_,· io lh<' irrigation .\yste111 were ohst'JTcd .-\t the time of our first quarterly monitnring, wccos ,vcrc :1bund:rnt. cspcci:i\ly in arras whrre mulch n'as thin or l;1ckin~. f)urrng our v.•co11d quarter~\' mmiituring n\ir. 11·c oh.1·nTccf 1'1111 mailll('IWIICC' 1,·or/,: /rad sig111/icmu!y rcducl'd 11·eet!~· rhrri11g/101t1 all o/ tll<' sil<'. exn:ptji,r 111·0 arco5 in tht• 1rortlnn·.\·tcr11 Jmrtirm. /Josed rm con,·tT.\(lfhm., 11·/dr rhe <l/'Jllic·mlf. moi11tc11m1ce condwNd a/;"r rhe S('crmd q1111r1crly monitoring lmJ n·mm·cd the \l"{'C'ds in tfu:se IH"O ((l"('(JS i\t the time of our fir.,;;t qu.:irterly monitoring. mulch was not present around the pedmclcr of the stormwatcr pond or norlh of tl,c ~Japlcwood Creek culwrt. North of th<.' stc1·mwatcr pond, hox fucl/nrnlch frnd rompactcd and thinned sin re ii hnd been applietl tho previous year. I )11rw.s: m1 r sc'conrl qua rf er!.,· mon i lorinp, , ·is i I. , q · ohs e rn·d r hat mulch 11 ·as I )J·cscnt rhnn1glwllf oll f~(tlw .rile, c'.\"Cc'/Jljor 111·0 m ,'itS in the 11c1n/nr('.\·tcrn pui"lion. /Ja,,·{?d 011 , ·om <'tst1 Ii 011s 11 ·i, h I I, c' ap('I in 1111. nw /cl, )or thnc I"<' ma iii i 11g IH D <I n•o.v has htr n tklin.,-nl lo f/w site mid u ill hl' spr<'acl in lh(' n,·ar}rlfurc. : t 1 1 ·1•,1 '"'~ !t • ,r .... , "r 11.,c ~l-!-1219~-0D) 1 SHANNON&WILSON. ING 5.4 Wildlife Ohscrv:itious Durl11g our rnt)Jllhiring. v1s1t .'.-l'\ 1..:rai wih.\11k t1bsc1 \·a1io1r..; \\l'i'C 111:uk. ,\ gr1.'L'll In.:,,: ti"og and deer s1.:at \lll'l"C nbsl.!r\·L·d w1lhlll lhi.: butkr mitigati(111 sitL' .. -\ rcd-1ail hawk and ~111 unitknlilicd snrnll r;iplor {puknli;1lly a ( \l1ipt.:r·-. h;m-kJ, wen.: ohsLTVc..:d c1m.:rging frt1111 trLT::-growi11µ t111-sill' alor.g :\-1apk:'-vood Crl'i.:k. Rock pigL".lrls wcn: t1b:-;c1"\'L'd in Ille s1t,rn1w~1lcr pond. (1,0 CONCLllSIONS Pcrform,.1ncc st:rndards for tlw hufler mitigation Sile during lhc lirst YL'~II ('I nwniloring are h..tscd on survival of in.stat k'd vcg<.:l~!I ion and ubun<l;mcc or'-~ L'cdy SJll'cn.:s !ist(.xl by King ( \ 111n l _v :is Nt liH,h . .:si goaled Ni. . .\ ioos \Vc ... ·tb and Weeds uf ( 'oJH.:<.:rn. P ... ·r1.·c11l :1\.·ri:tl cu\'<:r P 1· •.n .. 'l'tl y spec il.'s mt..."'ct:; th1,~ performanl..'.c st,mdanl ur having less than JO pcrcL'llt cu\·cr i;1/'wct...·dy sp\..Tics. \rlont1li1y or insla!lcl! v<.:gi..::ta1io11 \Vas cstim:ilL'<L b;tscd on st..:\'"l'll s,1mpli111.'. 1r;mst..:l'"L..:.. ,is ~7 pi.:rn:nt. ·,\ ;".icl, 1~ aho,·c the 15 percc111 111orlali1y ratL" spcci li1.:U in the pcrfonnan~e ·°'1:111d;1nh for quancrly nwnitnring. l imvi.:vl'r. this iwrli.lmH!ll't: slc.:nd;1rd !:-; h;.lsic.·1 i 011 llll'l'ling survi,·,il thrcshohh: for t.:ithi:r ;:ill <.1uartcrly mornlliri11g c\'i.'nls 12_1~ .it th<..: cmi llf )"L'ar l11h.: ba:-.nl on a c{1mprchc11sivc plan! <.:ount, r!1crcfon . .:, L'(1111pliancc with this /ll'rli.m11~rncc stam.lanJ should be 1..·q1Ju;1tql ;1l1cr lhe l'lllllpn .. ·iicnsi\'C plant coui,t is ctH1du~·t:.:d this foll to tH . .:curatdy d.dem1111L' pc.·r1.:1.·nt ~~•f\'Lv:,! rn1 lhl.'. entire silc. The findings an<.J urnclusions :!\Kllmeri{cl! 1n this rl'port h11ve hl'ul pn.:pan.xl fi1r s1xcilic :ipplicalion ·n this projt:cl. They lwvL· hccn dc\·clopc · in ,1 111;.111111 .. :r cn11~istcn1 with 1h::1l !c--.·cl of crm.: :mJ skill nomrn!ly cxcn.:iscd hy ,rn.:mhcrs <.1 f ,he cpvirn11111cnlal sclct1l'l.' pmksswn 1..·urn~nt!y pr.icticing wHkr similar r'{1nditinn .. ,-in thL· area. Tiu: cnnclusior1s amt n.:1,:nn11ncnda!iom:: prcsr.:nfl~d ln this rcptwl arc proks~ional opi11wns h:.H;l:d on int<.:rprctal:llH1 of in(l\mwtion curn.:ntly availah!c to us nml mc,lk within the opcrati~Hlal scopl.'. l1udgc1. nnd schcdlllt.: 1.."011:,,;tr~1int:,; ofthi.s prnjccl. !'!t; w.1rr:inty, cxpn.:~s or in1pli 1-'d .. i,.; mndc. Thi:-. n:port was prcpaTL·J for the exclusive us!.'. of' Tom FtlslL'r ,:ind his rcpresL·ntali\·cs. \Ve ha\'c ;'rcp,ired 1hc doc-uirn.::111. "lmpurt;:mt lnfnrrnalil,n ,\h.pul Your \Netland DclliK,1tit1ni!Viil1g(:1ion . I i I '1'•1 •••~ 1C ,j,.., ~ "I' l~,I 7 SHANNON &WILSON. INC. [(l'purt." (,\ppi..:nJi:•: Bl tn .:.1:--;:-:i~t ytHI nnd olilL'rs in und1...·r:-;1andin1:' till' usi.: ;,.ml li111itatin11s ufuur ri..'p1 lrts. Sll.1.Ni\'ON & \\'JI.SOi\, L'iC. l?v ;o ( .. s_~"~---~ l3rnokl· Lrickson Hinltigist ' SHANNON &WILSON, INC. ., APPf,NDIX A PERFORMANCE MONITORING DATA SHEETS '""), ]J.1-12193-00, . ' ,. "' 4: "' " " U) '" ... Transect o, Ptol 1 ~ 2 J ' '---- Qu2nt1N 1 ,,_ "I 3o 'J.-1- Ba!lcline Event % Cover1 Y~ No;,d0\IS 1 ~. {L, "r.. .-, ., N/"- -:,.,<./ fJ{,._ ~,. Thi:!! l'M Elicnl Quanliru' o/, "e? I~ 'I . I 0 --,o., ,Z..I h 'r.1- ~lM' SHANNON&WILSON.INC. ,;-r.v c::¥ % Noxious 1 ~:.l.'.r,,._ < ;z "'· < :z. -r. ,/-0,'\ 7. No. of TRANSECTS ·~ No. of PLOTS Ch3nge !rorn Base!lne % S0rviv.i1• % Cover~ % No;itlous, sq (p -c, <I< ;; ., ~ " 'L-., .4 I 1. '"'· I .,...., " U) ~ "' " z ~ 'c z 0 " 5 ID ,J/~ ~.!. 'I ..,If>,. <nSY. ' I w q_') Ll£A I I 1-f IL; a< 7 I" 'l . .,_ ~l,t,. ,r., 1 '3 as -- 8 • ---·-- 10 TOTALS l",0 ~-a. •f. --10'-1 I 3.6 •J. _,,, O~ot a;..,. For del:lilerl perfo.m;;uxe moni1orm9 1e~ull$. tile~1<;c refe1 (o lhe 1nd1viduJI l1.in'.";ec.lrplQI d;:it;) shee\ 'Quan1,1y ,s oC on•y insl.illed woody pl.ir ts <" % Co,..er u1c.lurles. ,nst.ll!l!'d WQQC.ly .1fld deSlfatile 11o!un1cer pl.;inl!. 40 -:ro ,}t/ ~ -:/-3 •/. -t-; % '"Yo No(io1is includes no.:ious weeds aml those spet;1es spec,fic.ilry c..it1<1d oul ,11 thP-succ.1;::;.::, critefia 10 g ti1ma1aynn b!acllllerry) ~ % Survival 1s .i rela\1ve i;;aPcvl.1l•on tt;;i'$ed on 11'1r! orig,t1,1l f"iumti~r or pl<:inls msl;J~~d v11lh1n 11,e 1r.in::.ec:t'plot lo 1110$e still h-'!r'IIJ < 0,0/ ·;. B) GENEF.Al VEGETATION VIGORlliEALTH: s~""" ..i~J-.._hQ"' A•'.·.,..,.,, W<:ti1 .c.1'{<-.... Jl, ,....,.,, ... L.,.:, .... 11....{l~I. .. -=. ~(t.1 .... + ·f't>'-·~ \ .-,,n:.~h')f. 1 t,<?,; r.)~·~.,·.J. 1 .. )..J~•~ • .... 11 .. -:--" .;,.-.... . H.,•H'",l ~ .. t f--,,l.f 1 lt' 1.-., .... Hu .. ,....,. "r-t.,,3 I C} WETLAND HYDROLOGY! :a t.J /i\ 15 z il ~0~1"N"o"x"1o=u=s1"N°'u"1SA=N",,"e:-ccw"e"e"o"c"o=N=c=Es=N=s-, -------------------------------- g: 'p)-r.t.! c..,,;,.,.,_f-rJ OGtf'.,,..h ~"'"'-d.v ... t.,,J.. w"....d!, .f:<>~ f,11•')~ .F ~ •'\ f;,\.,_.f-,'o.,,,_ ~J·,iz,, J\rP..f.. ,.,J ,. I ! ~i..J ~~ ~·,h sh\f "t.iv,r ... \ ,~.1~ .. J.. ~1"-\~v .... /. 1..J.t.-u{ <-,n,J~f 5~ ... IJ &n.f;qV"(. f-!,,,,....,.,~r,··) .. --h prc.~-<t·J.' ~ ~·<~t1t.b\,<:."w\\l.,1, .. ,,t . .., -------------------~ E) WILDLIFE OBSERVATIONS (DIRECT .ANO INDIRECT); u.l \\~tA...\-.... 1\ \o,,._,v'M_. A....,,( [i~'\iJ..c"'h~·..J..l :,.M..,lt ~"'rh,r (f_,'S~•~i ..., ,',..,.'f'''·•J,._~ O~H"":;4l.r\ iv'\ .:,.,:-oJ..•,./.. ,'\r,'<, ~ O\.~ V\li,._f1<,t.w,.,.J <:.~u..L...· {;,.· .. u....,, +:-.-.: .=,...~ .f .~y' <,,,:,.,}· u\:.>j~rvv( (?II 5h: p,d,c. ... ,.....~ ,\., sf" .. ,.""' ........ h..r f·'-ld., ------ F) MAINTENANCE CO~CERNS: 5c< i>} ..,,._==--------------------------------------! G)OTHER '-------~----~~-J r-··· ----, j DHICR M41><lE"'-ANCt · ,----· I I .... ' .. i' r. WlLDllf'E. I. ., l\"-l . i "\ .! • f- ! I· ,- . , ·• " ., ,. I .•. ~ ... .l ~) ; , . . ' . ~ '. ---· ., :, -· 1 } -__ } I'.·, (: . J I L ;":'.;:~it SHANNONf//JH--SON.lNC • :,,..,, 11i\.~&~l"--/'1"~ A~ 'l-~-,•d,,r!-·""-: H i!:;.!.Wlllo. ;:..1-1~11..1~'3-<':lo':i' : Q iUOtnOAIN(' EV'i:NT "l..v-"'-<ilt-.- i f !laSER'IER 6AE 4 -?c..1 -JRANSECT O.,.,ENSl0"1Sc jQ_ t, w,d1n X. j,.. }._ 11.. 1 .. r,9t11 HtAf.151:CT .'lo --~-• "OATE £/t.t,/-O°'/ -, GENER.Al ~NfORMAtioN BASELIHE; eve· 1HLS ,.10NIT .AING EV£MT lr Cf<l1'.l FR~ IIAS1:U/l£ :--Sym---;;J j Common l'b,m• I SclMtifk: Nilme QuanUrv1 % Covtr' Covtrlvne• ~NtEJr,t,,1 I Qu.anl!!y "I. Coyer I Co._,,, hoe !I 'J, Suro,1·,~11 ! 'I. ::0·1,11r ;; a :'.) a ~ ;c :: • .g u .~ ~ :i:..,,;,, .. ., ;>I.,.,-, I o..__.,1 •• ;. C.., •• ,:,..:,, «. o. ~ ""' :f. i 9 a.; f St, i b S-1. l ·....:__:"·/', --1'·\~l-'-OC'7\...-..-_~ O\...;\.,,J.i_W 1~ J .... ,.-·,;_ I t.J---:i.., ")~ :C. 1 4 / ~,$<\ i 'il ~ i(x..).:..-'~ l ' I , ~ ~ .\'1.... i\k,1.)-h..:..A •Cx.. ·~ ".i.:-. 11'\1;+-l.,I'<... _1'1 O,G <;.t.,., ~ -f--3:: j 1-9: 1 c..~, i 5Y~ i _ . • -....,v; ! 1 .. ~i_<:.! ...... 0,, ......... -,'.)_ 1'-1 ,,V\.~··.",,,,_ .... ~ ... ~o\,·v....... 'L ........ ~ I :s !..._ .1 __l__ 2..... i 0,-, -I $ h t '00""'.'.: I------' :_. C-:±_; l?\4,J.sG~-r\""u~1 "'~~A ?e.fvl-..) l,:,,.,~\11,;._,f~,.._ 1-J/A '?,":r,"') \ M C. I •'-/", ] .:'.'.i~. -r'r-'<'£,: ~ .vf;t ] · ' D \ ~ ,;,... '~ I> 3 0 < I ~ ' ) I . ..< ' " :. ' ~/ ,, [\p .. .., ,'!-j'1·· C"d.DI) ,iu,1t.,c>'l .'i "ll,.. ~ I IOL,\..<..., j i':': j I"'/.-., ~·--~-''-c--r----·-~ _ :.. i_...•,n~ .... ., .:; ... 1.· ... <...-..1 ~/A o.: '.'JI,... v na,\..,L. g:i j 1\..:/1 ~ ;--/:':\ 1 j I I I I !1 ---,r------1-------r }-----t---=1 ~---: . --! -+=ii! !i ; I ~L_ ~-- ! ~I " ! ., j .. ------·-· -· ---_ . I =-c I ; I ~ T ' 'l-" - ----j II ] I j j --,_',---------- " ____ __J[ ·• • ·--I f--------~ I , : I I . 1 pc•,.s : I '3 C> I "r'f---'2-0 I IQ, j 'l',I j &,;., .?-r.\ ~ Sr!M'Ol uull In bcrt ttans.c:t xtuimatk. !Ut:k). ~ Q11.1nllty Is or lnMalltd planu: omy, 1 % Coy« It. Ui. ARiA ~lnsce.lCt!d 10d vohatlleor pltlll:a tt,te Cll\c:ulatjon,.on ~ • CoYtT 'fypt: 1 .. t't11•, Sh .. Sl'l~b,-SI • Uva St11«1. JI' tJLIL!Yelumw e ... e:,;1&1!® N-. twtGU1ww.1uira. • :% SW't'IYflJ Ii, rt11t1vt eah;ulatf!NI hf1tii on 1b1 or:1a1nat nurnbitr # P11011 IOK1Utd MJh'n lt)q tm»ttfiPlot 12 thou 1011 HYLM ' . '' '. I ! ~ \ Ii j G~u"' +· .. -« f=j 01.,,,,......1. '"' '--P\'>.~ ..., . .i-,'.>~b .... !-14 f-~1 '\ f' r".~ .. .,,t-. m1·,, .,. -, i j L,,<2_.,_u.,,~ ~ ..,-c:...,. , .._"'"\.D'v<O-, ii 1 I~ I w.,l-.,~ <Si,.-1.c~ ,. "'"'J \?o:s,b°'"" l~~ ,._,.._"') H,I,. ctr p\~-t ~lt. ... t .. t,.., . :; .. " ,, • , .. , .. :. ===Ill ···-____ ji. '' 1----1----. ----; ( · -·--·-=~ !; -------~:: L... -----f----. .... ·---~ I---... -----+-·-~-:=t=·. -- -··-- --·--· ··- ®' 0 tS (.~ i:,,).r ' to ·I( I i ' I '° H~ll l'{lll1StCi"s"C~K:M'1.TiC" ..... ··--· ' ,<·i~·"''1 ' '0 '.11'•~' .. :1 / I ' / "1-p • i + 0"(:, -~ o~~[ On,,: ' O""'-' r · -tv ~ ' / (W .. lift i .. I ... '@ . , / ' .... -t o.,~ o;i:p O.Ilf 0 . '. • ., . "' ., ' cl ~ 2 0 "l I ~ ' ., I z (") 0 z I ' z " (/) u r 11 --··1 I ' I ~ i'.i z ~ " I I I I t I _f I 1 I: I -~ ~ I I.~ i I ..( I <>-<>-< -;-1 <.,:' ,....., • __f " . ·, J 1= r, 1· ~ r.: r. f .. f . --1;: _ -_:r =11: :-_~ :--~l:_-~~1:-.,. -· ---t-- ~ ··1···. t -... ·.1· .. .. . .. . . I . . I . . . I I ! l ··-· . ·-·. ar.1" t I" ~ 01-f + Q ef!) @u:1 •-··-~·4', .' • .,, ~' . VO) / <) .,__ ,_ __..:_ __ . C! J'~ . ,~ ••• @· ~ .. ,.!.;.~ _t".r-(.A.. C..,.v ... v. . -f\1.(,.,-. :/-'.1-. -. ~W~-'o~ ~ ?~ He.1.cir.":-'t.Q\J' C:.v,.,..r. · c.~-..!(.n-,l.1 . .., ~ "(,, -.,;., ,1 ""·d"\,t,<.>t-.O l ,_.:,,,1r,vv, '.ti;.~.~ / \,,...+fv,..,.\;i -< ,'i.,B -.}~ . \.J.., ,S<h) ' . Cw\') J_,,,.J._ / • . ~- I 5 ·I :,1 !": . ... -., .............. -.j·' v " ~ --~111 HANNON & WILSON, INC. lJ(ml1'c:lmi1:cll ancl f:nvironmental Consullanls I);, I\·: ~q,.t _L'!11l?~·r}. 2,_ ;rn,.? .. ·-_ ··-·-____ .. , _____ _ Tn: ___ Ml'. Torn 1:ostr.:r . ·.·t •• .. ,., ... _ h)1_1r11t ,t,.,•t•nu.l: t\.,;~oda1_cs,,UX ·-·---· IMPORTANT INFORMATION ABOUT YOUR WETLAND DEL.INEATION/MITIGAT!ON AND/OR STREAM CLASSIFICATION REPORT /\ Wf.H.ANDISTREAM R~PORT IS BASED ON PROJECT-SPECIFIC FACTORS. Wdland tldt11~·a\l1\ll;llllhJt,l\lt111 :1t1d Slh';1111 dit .. 'ilrK.1111111 rqh•i1'.\ ,1r1..· h:ISl·tl llll .l IIHiq\11.' St'l td" proj,·d·SpL•dfic n,clurs. ·, h~.'il' lypk;illy ,11, l11d1' ,h"• Jl1'/ltT;d 11<1htlt' nf tlw prt•wri ;1rnl plo(ll'l'IY 111n1lh·d. ils :-.rt.•,:. ;111d lls t',_1nfie1.1ratl'm: l11s1nrit·al u:-1.• anti pr;u:lit,;L'; the ll>C.ilion nl tl1~· 1111•11·d 11111h1· 1,1k .in•I m, 1•11r11l.iln111, :11hl llw l1·vt·l 11frnld1111,11;1l nsl.. llw l'lil'lll .1:-.,mHl·.:l by ,·i1rllt: 11flimitatio11:,; imp4\Sl'd 11p(11J 1111· c.,plnt,IIPq' ptnJ~l',1111 lh1..· _1111L;,,d1d11,11 tif -111.\' p,ir\h..'111.u wt·tlaudf~l1V;1m i:-; 1kl\'l'lnii:nl l1y Iii\· rq:ul.th•ry ;nHhndty{s) i:,;:,;uing lhl· ponnl{·il. !\s ,1 h':--iUlt, 1>!ll' nt 1111,rt· .IJ'.t'IKlt·s will haq· 1111i:-.1hr1i1111 o'.'t'f a pi1i'li1..·1ilar w1•!lantl or sm•;uu wi!h .-:~1111l·limcs cor.;fusin;i 1q:11l:1lJ1111-. 111•, 1wc1·s-.a1y 111 m,1d,1· ,I 1'1)11s11l1111it whn Lllld\·1..,l;mds whid1 ;11'.t'IW)i,.;) ha:s juris,fo·1i111) 11\'1·r ,1 p:u1il'lliar w1.•1l.11id/s\rcmn ,md wh;il 1h1· :JJ'J,'lh'Yh) pnr111ll111Jl. 1np1m·111~·111, ;,rl· 1111 t:1:11 w1·1hn1~·s1n·,~111-h1 help 1\·1h1t:1: nr ;•v11itl pok11l1;1l 1,;n:,;tly pnihkm..'>, hnvc 1!11· 11tn:-111l1,m11k11·, 11111w hilW ,111y 1:-1(l11r:,, 1or 1q•.ul;1111111., (\\ h11 Ji t·;u1 l'hangr :,iuhs1..'(ll!L·111 11, 1h1..· rq1111 I) tllil'J o1ffl'L:I tlw nu1mtth'J1d:llit111s, ,. lf!hr :;1n· nr 1·n111i1.:u1a1i,,u nl lllt' pr11pnst·d p11•i,'l'I t~· ,1lh·r1·cl. • If lhl· liw,1111111 ,:r 1irit·111.1111,n 1lt' !lw pwp11 .. ,·d pr11jL'l'I l:,, UH•dilinl "' l f tlwn· i.-.. :1 d1a111~~· ,,t' ( ,Wnl'r .'11111. • h,, a11phrn1iun h1 ;111 :tdJin't'lll .,1h· • hir n,11s1m1:hm1 :11 ,m adpn'nl slit· 111 011 "lit' " Fnl!t11\·1n1~ Jl,111.ls, ,•arlh1piakt'.", 11f :1tlu·r ;1,·t.~ 11f m,11111· W1·tlao11.'slrl'llT11 t'llfl!o;Ullilnts cn1111,,i iH'rqH t1.·:,p1111.~1h1h1 ... f11r IH\1hk111s lh;11 may dt'\Yh1p if 111,·y ;m· 1101 1.:n11:,;ul1,id ai11..•r f.m;lun: c1111sukn·d i11 1l1dr l'l'\llll'l.'i h:1w dlilll)~l'ti. l lwrl.'li.,n·. 11 1.~ im·u111lwu1 upnn yon to mll1fy _v,,uc rrn1s11ll:1111 of any foi.:11111-1h;,t1 may havl" i.:h:u1i;t·d pritir 1c1 ~uhmi;;:-;i1111 of 1,ur lin:11 11·pon Wdl<111d hou111l:tric:.· illt•111ilkd a11;.I :cltt'.1111 dn-..·,;ifirnlion:,. 1w1tl1• hv Shanrh1n & \V1lsi111 ;ire n11\.'l.idl·ri.:tl pn.."lin1in:1rV lllltil v11lidaicd by the I LS, 1\n11y { 'nql:-; ul Lul,litwcr . .., {( \,rp:,:) <llltl,ur lhc lt1l·nl jt11"1...:,i1l'l11111al a)!C:11\'y. V:1li1l:ilit1J1 hy Ill\: r1 . ."1,!lllalin~ ilJ;!l'l1Cy(sJ pruvi<.ic 6 .:1 .,.. l'.tir1ilit:acio11, usu.illy ·wdHl'll, 1li;1l lht· w1.·tl:u,,! h11uotlant·s h'nfo·d ;u~ 1h1· lio11nd,1rit·,'°' 1h;1l will h1· rq;,ul:11t.·tl hy the :1gcncy(s} unlil 1.1 spl.'i..'ilii..·d liah·. m uulil lilt· rt.·1~ul11!i1111~ al\' m11l11linl. nrnl ;lwl lht· ~IJt·:im ha:-. tll'l.'ll j'lrlljlt.'fly rl.1s:-.1fa·,I. Only lhL' n;gula1ing, agl'm'y(s) 1.:;111 provilk 1his L'l'l'lilica1i11n. .,. ... . ' MOST WETLAND/STREAM "FINDINGS" ARE PROFESSIONAL ESTIMATES. Sitt.· c:<11lnr:i1h111 id1.•11tilics wc1hm1ll:Hrl'illll t:onJi1to11 . ..; :11 1111\y !h(1:,;(.• p,1it1I:-. whi.:rc :-;111uplci,: ,,re lilkL'II nnt.l wht•n they arc 1;1k1..•11. hut the rhy:-;ti.:al means of obrninini::, 1k1t.i prL·chuk· 1ln· tktL·rm111;11in11 nfpn .. ·L·isl· 1.'1>nJi1lt 111s. C11nsc~\Ul'nlly.1ltL· infom1.11inn ohtumcd is inh:nded to be suffo.::icntiy :1ci.:uralc,.· li:1r dcsit!,U. htll 1s suh.11.·i.:I lo i111e.:rprl.'lntiw1. ,\ddilion,llly, tbta (kri\'l.'J 1hmup.h :-,1mpling and ,uh~<iuenl lab(m1tory rcstii1g ar~ :.:xlrnpolMetl hy IIL\" cpn:-;ultarn wh., 1Ju•n rcntk•n: an tir,imon aborn nvt.'rnll 1.'\)ttdititms. the likc:-lv rcacrion to pmpo:-.c<l 1.:.on~truc1ion a<.:1ivi1y.1111dh1r 11ppl'oprt;1te tk:-1~11. h·1.·n undcr~,ptinwl Lirrnm:-1,mcc:-:, <Klun.I 1,;:111di1ions m:iy tfifl~r from 1ho,,;e lhought to c:<h:t bccausr.: nu co11..;ull;mt. 1111 111,1tll'r how ,1u;1tilit.·d. aod nu cxplor.1tinn pro~rnm. llll mnncr how comprcl1cmfrvc, can reveal wh.11 i~ hidden by l..'Urth, ml'k, and lm11.•. No1h1nl'. cm he dmJl' 1\1 prcvt'I\I tlu: un,111\i('.ip,11cd, hu: slcps 1.·m1 be tnken h.1 hdp reduce lht:ir impnct:,., For thi:,; rcasml, 111llSI cx11cril'1ic.:1..'d ownl•rs rctnin lln;ir ct111."<11lwrn~ 1hn1ui:h the i:tiui,:!ructfrm or w1.•1l.1nd mili!;:rttionf:mcmn cw clas~i:icalion :m1l!.c lo itkntify varian,·l~~. In l'nndu\!I a<lditl,•o<it cvalu,11hir1~ 1ha1 m:1y he nt.'l'dt•d. and lo recommend solutions tt, ., problems t'ncountcrcd cin ~it,c, .. ·' " \· ._, 111 I~ .. I ~·· WETLAND/STREAM CONDITIONS CAN CHANGE. Smi.:r n:rn1ral sys(i.:m;,; an.' dyn.\t111c sy, ... 1rn1s all\:ch.·d hy both nnturnl prrn.:L'-"scs and human :u.:tivitic:-, ch:in!,!.1.·s in wl'll:rnd i10u11dJ1riL'S ;:md .'-ln:.un i.:1,111tliti,,,1:-: may h1: i.:;o.;pi.:i.:h·d, Tlit·rl'!i1n·. Jl'11m·ak·d w1.:1bnd h1111mfori1..·:-. ,rnd :sln·:1m d.1ssiJii.:alin11:,1 i.:11JH1L1! n:111;1i11 v,did rm au i1llkli11ili.· pi.:rioll of tin11..'. Tiw t.'111-ris 1ypit.:ally n·t'1)~11i1.t..·s 1ht· \·;1hd1ty td' m.·thmd dditw:11i~1n...; for " r..:ri11d nf live y,·m·s aJh:r i.:n111pkli\1H. Some 1:ily and i.:1it1111x ;1g1..•1wii.:s rL·~ogui,.t· th1..· ,·;ilklily 111 WL'llil11d dr..·h11i.::11in11;,; for :1 p1..·rind of lwo Yl':ll"s. Jr .i pl'riod nf y(;-11.s hnw p:.1:=:scd sino: th ... · wdl:ind/str~·,11n n.:port \Vas t.:rnnpkh.-d. thi.: (twnn 1.,:, <t~h·i,'>t.:d lo lwv~· the.· 1..·011snl1:ml ri .. ·i..·xamine !lit~ WL0 llundl:-:ln\1m 1t1 dt·lt'l'lrnnc it' fhl· dnss,fo.:nliou is :,;I ill ai..·rnrnh:. ( \111:.;lruditm op(,.'l'alt\lns :11 1ir ad1ai.::t•1ll h~ th1..' :-ilt' 1111,l 1wtural t'n•nl:-sud, ;is 11~111ds, L'arllu111:ik1..· . ..;, ur W.Ht:r ll11rru;\lin11s m:iy ;l!Mi nlkt:t ctmditit111.'i a11d. tlms, lht' ~L1nti11urn1: ,nkq11;1~:y tif tlll' wvrl:md·'slrearn rt·port. Th·: 1..:nn:-:uh,u11 sh1111id hl' kq,1 ;1pprist:ll pf 1my :sut:l1 t'.\.":11L~ ;rnd .,;huuld ht· t't1Jls11iled 111 llL·t1..·~1uil1L' 11'additi11n:il 1.'v;1ltw1in11 i:-; nn·i.;~;1ty. : ~ TliE WETLAND/STREAM REPORT IS SUBJECT TO MISINTERPRETATION. i11ff Co:-tly pn1\1IL·UJ~ 1;;1n 11t'L'lll" wht·n pl.111;,: ill'l' d1..•vd11p1..·d ha:,;L·d ,111 1111:-:1n11·q1r1..'lalri•ct i>l" a wc!IH111h•1H·;1111 n·p;irt In lu·fp :i\'nid :!11·:-t· / g pr~1hk1rn:, lhi.: n•nsu\\;111[ .-:hould lw rt·laint·t! h> wnrk wilh 11111•.·1 :1ppropn:1lt' pndt·s~in1wJ..., hi \::,,;pl;11n rl'l(·v.1111 wdl;u11L ... ut::irn, g ... ·nlugi(;d . .:rnd nlhl'I" lindi111.~ . ..:. und !n n'\·i,:w tlil· ackqn;J\·~ ,,fpluu,; :md !-pc,·dil":il11111s n·L1tin· 1111h1:sL' issut·s l ,-,1 ,, .. DATA FORMS SHOULD NOT BE SEPARATED FROM THE REPORT. hrntl dala f'nnn:,: ar~ ,k\·du1wd hy lht· l'•JJ1"lillau1 b:J~l·d Pl\ 1111t'rprL'l;1ll1111 11r rit•ld :,:lil't'ls \a:-;:,;1..·rnhh:d hy srl(· p1.•r:,:111m"',l) :md l.1hura101y l'\.';1'u;Him111f fidd ~arupk . ..;. ()nh' lin;;l da1:, li.)rn1•: 1.·11:-!tHl\;11i!y :ifl' mdud1..·•l rn a 1vp11rt lh~-....:(· da\;1 Jlinn-: sh{1t1ld 11nt. umkr .111y ,:il'i.:ums1:11h·1.•:-., h1· 1\r:1wu litr inrlw-111111 1,1 11ii.•.'( t!J<lWUlf." h1..'f;t\ts1: ,lf~1lkn,. 111;1~' L1 11t11111t l'ff(1r~· 11/ 111111s:-.lt>11:-in tlw !nu1sJ~·r pr111:('S.~. J\hhllugh ph11111graph1L' n'[Hntllldtull t·li111i11a1t·:,; 1hi . ..; pnihk111. JI do<.'," u11lh1llt~ tn ll'dtJt't' !hi..• pw;sibilily 11/· 1111...;10\l.:rpn·ling lhl' fi1fnls. \Vh1..·u 1f11s u(,:(:Llr:;, tldny.-:, dispuh:.-:, :llld 111iamit.·1palt'tl r.:usl~ ,in· frt.·tjlli..'lhi_v 11\i..· r~·:,;ult. 'Ii, rl'dUt.'t.' 1hl' likdihnod ,if Li:ifil !i1rm 1nisi11tt·qirc1a1i,111, cunrr:1t(ms. 1,·n1:inc.:cr:-:, 1t11d planuns :,;hnuld hl' giv1·n rt·Htly ;1...:1.:1·:-::.; 111 llw r.:omp/ch: r~1p11rt. Thn:-1: who do t1(1\ provilk sud1 an.:cs:-rn,1y 11nii;('t·d uudcf tlw 111i:-takc11 i1upn,'s~iou thal simply tli~d;dming rC.'iJWllsihilily for dti: :tL'CUl'ilL' .v 11f i11li.mn,11i1111 al\\'ays insuliill'S lhr111 li·orn .1Ut·11tb11l liahil ity. l'n1vl1ling !lw h1,::.;t ;tv.iil:ibh: i11ti1rm;lli,,n hi 1..·t,ntrat:l1,n;s, t.·11~1m:crs, and pl.rruw1·s hdps pn.·,·1.:111 l'l1:-;tly prlihl1•111.~ .uul 11\l' ,1d\'l't'sarial ,wi111dt•s-1h,1t ag~ntlt.:JI~: th1.·111 ti·1 a {lispn1p1w!it1na(I..' scak. -., READ RESPONSIBILITY CLAUSES CLOSELY. ·.:., ... Bi:nu~·.: a wc1!1rnd dclim:~11ic1n/s1r1,:am cl;1:-.sific;11io11 it-: ha:.;t·d l\'\H.'nsivdy Pl! jud!!,mt·nt ,111tl npinion, ii 1s fo1 le:~:-~.x11c1 i!mn t,lhcr tk~ign disi.::irlinc:s. Thi!-i situa1ion Ii.ts rc~ult1.•d i11 wholly unw,m1111tt.-d d.ii111s bd11t, h1dJ.:.l'd ill!<1i11st Cll!tsull<mt:-;. fu ltd1l pn.:Ycl\l this proh!cm, t;om;ult:u1ts lmvc JcY'\.'kipcd ll nu111hc.:r nt\:l11usc.,; for osc in wrilll'li lr.111smi!l,1b. \'hc,~e arc uni l\x1.·ulpa1nry chtusl's ,lcsigncd to foi~I lhc ·~ co11:,;ult.1nt',-: 1i,1hilitiL·s nnlo s<1mr:<111t..· ds..:; r,11hcr, lhL'Y arl' \ll'lin1tiw danst·s ifwt idvnlif:v wh,.:n.· tin.· l'.nn:-ulf,mt's respo11sihili1ic:-:: hq;,in .and i:nd. Tlwir use hdps all parLil'!'> involvcLI rct.:t 1g111ZL' lhcir iudi\'idunl rcspoiisihilitil.!:,l .tml lakt: np1lroprintc aclion. Some of thc:,;c ~ <lctinitivc cli'.IUSL'."' nrt' lik(·ly h1 41J1p<'ar in your n.:pl1rt. ;mJ y\111 .ire c.:nt'1,ur:1gL·d In rt'mf 1hc.;m dusdy. Your i.:onsull.\nl will he pk•.isl'd lo give foil nmJ frank arnrnw~ 1(1 your qucstiuns. ,.. THERE MAY BE OTHER STEPS YOU CAN TAKE TO REDUCE RISK. ;~ Your con:--ulrnn1 wilJ he plea:;;cd lo di!--ct1."s other lcchniquc!'i or designs 1ha1 c:an he employed to mitig.itc 1hl'.' risk of dd.ay:-; nnd 10 provide ri variely ofullcmativc:,; that nrny be bcm.:ficial lit your 11n,jt"1;t. """ . , Contact your consul1a11L for fonher infornmtion . ... - Page 2 11r 2 February 18, 2014 Approved By: City of Renton PRELIMINARY lECHNICAL INFORMATION REPORT FOR Whitman Court Prepared for: Lozier at Whitman Court, LLC 1300 114th Ave SE, Suite 100 Bellewe, WA 98004 Prepared by: ESM Consulting Engineers 33400 8th Avenue S, Suite 205 Federal Way, WA 98003 02/18/2014 -~-·i ·-1 \ '1 ' , Job No. 1799-001-01 3 Date TABLE OF CONTENTS 1. PROJECT OVERVIEW ................ -... ··································································-·······························-··-··· .. ······················-,····················· 1-1 2. CONDITIONS AND REQUIREMENTS SUMMARY.-................................................................................................. 2-1 3. OFF-SITE ANALYSIS ....................................................................................................... -.. -........................... -............................... -.. -..... 3-1 4. FLOW CONTROL & WATER QUALITY FACILITY ANALYSIS AND DESIGN ............................. 4-1 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ............................. -........................... -........... -.................... 5-1 6. SPECIAL REPORTS AND STUDIES ................................................... -............................... -............................... -.................... 6-1 7. OTHER PERMITS ................................................... -.................................... -..................................................................... -............................ 7-1 8. CSWPPP ANALYSIS AND DESIGN ............................................................................................................................................. 8-1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT... 9-1 10. OPERATIONS AND MAINTENANCE MANUAL .................................................................................... -..................... 10-1 UST OF FIGURES 1.1 Vicinity Map 1.2 Existing Site Conditions 1.3 Proposed Site Conditions 1.4 Soils Map 4.1 Pond Tributary Area APPENDIX Appendix A: Approved Technical Information Report prepared by Barghausen, Inc. Appendix B: Geotech Report prepared by Associated Earth Sciences, Inc. (AESI) 1. PROJECT OVERVIEW The proposed Whitman Court project is a 41 lot plat with 40 townhomes and 1 bank located southeast of the intersection of Union Ave NE and NE 4th St, just west of the United States Post Office., in the City of Renton, WA The project is 5.12 acres in size and incorporates three parcels numbered 5182100020, 5182100021, and 5182100022. All parcels included in the project area are zoned CA (Commercial Arterial). See Rgure 1.1 for the Vicinity Map. The existing site is rough graded, with a previously approved and constructed water quality/detention pond in place. The developable portion of the existing site is moderately sloped (slopes between 5-15%) and slopes down generally from the north and east sides of the property towards the southwest comer. At the west edge of the property is a wetland, which drains off site to the south. See Figure 1.2 for the Existing Site Conditions. The proposed 5.12 acre project site consists of 40 residential lots, 1 storm drainage traci 3 private alley tracts, 8 open space tracts, and 1 sensitive area tract. All 40 residential lots will have new multi-family dwelling units. The project area is zoned CA (Commercial Arterial) and the lots will be 814 sf minimum in size. For access, the project will utilize an existing intersection at the north end of the project site, Whitman Court NE and NE 4th St. Additionally, the bank site will create a new driveway access point on NE 4th St See Rgure 1.3 for the Proposed Site Conditions. A stormwater detention/water quality pond has been previously approved and constructed, and is located in the southwest corner of the site. This stormwater pond will be used to meet the project's stormwater detention and water quality requirements. The detention/water quality pond will discharge to the west to the onsite wetland. See Appendix A for the previously approved Technical Information Report, prepared by Barghausen, Inc. According to the Geotech Report prepared by Associated Earth Sciences, Inc., the site is underlain primarily by native soils consisting of Vashon Recessional Outwash and Vashon Lodgement Till. There were sorne areas of fill soils encountered, as well. Additionally, according to the USDA NRCS soil mapping service, the entire site is underlain by Alderwood Gravelly Sandy Loarn (a till soil), which varies from 6-15%. See Flgure 1.4 for the Soils Map and see Appendix B for the Geotech Report. The project is previously approved and vested under the 1998 King County Stormwater Design Manual and the City of Renton Design Standards in place at the time of approval. Based on the previously approved TIR, the project site Level 2 flow control, which will be provided by the onsite, previously approved and constructed detention pond. Additionally, the site requires Basic Water Quality treatmeni which will be provided by a wetpond in the combined detention/water quality pond. The TIR Worksheet will be provided with the final TIR. ]-] VICINITY MAP NOTTO SCALE Rgure 1.1 Vicinity Map 1-2 n Figure 1.2 Existing Site Conditions 1-3 / / , ' / ' ' - Q) ......, II eel C). lfj "..-1 ~ 1 lflc ~CJ-nCJ ~1::JUd~J(].li:J ,,J ~--,-l~~g:~.-~,--~~~----bl · I'<;. OON ~ ~ ru " 80"[8[ ~~! a ~L, ~ ~, ii 2 ~ ~ ~ ;u': , ' ' ~ Ji ~~ HITT i :z: _;z O ~ ~ ~ i~ ~ ...., § t 'j_ ~ -----~;Jl,lJ'UI .:, z ! I I I ' , ' / ;:J I f I ~: "' " I I I ------~ ! Figure 1.3 Proposed Site Conditions 1-4 Figure 1.4 Soils Map 1-5 ~ 47° N 19" N ~ ~ 4 7" "19'lrN ; ; ~ ~ I i Custom Soil Resource Report Soil Map 562980 563020 563060 563100 563140 563180 562980 563020 563060 563 100 563 140 563180 Map Scale: 1:1,810 (printed on A landscape (11" x 8.5") sl'€et N -----=====-----------==----====-iMeters 0 3 50 ~ ~ A ---===------.-------====feet 0 50 100 200 300 Map proJedior1 : Web Mercato, Comer coordinates: WGS84 Edge bes: \JTM Zone lON WGS84 8 563220 563260 563300 563220 563260 563300 563340 563340 l<) 4.r' 29' 19" N ~ I ~ ~ ~ iG "' I 0 ~ I c,: 47"'29'l i9 N Custom Soil Resource Report Map Unit Legend King County Area, Washington (WA&JJ) Map Unit Symbol Map Unit Name Acres in AOI I Percent of AOI AgC Alderwood gravelly sandy loam. 8.4 100.0% 6 to 15 percent slopes -·----·· 8.41_ ----------------- Totals for Area of Interest ' ---- Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however. the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. 10 100.0% ·- 2. CONDITIONS AND REQUIREMENTS SUMMARY See Section 2 of Appendix A (previously approved TIR). Section 2 of the previously approved TIR describes how the project will meet the 1998 King County Stormwater Design Manual's Core and Special Requirements. 2-1 3. OFF-SITE ANALYSIS See Section 3 of Appendix A (previously approved TIR). Section 3 of the previously approved TIR contains the Level 1 off-site analysis and downstream analysis for the project site. 3-1 4. FLOW CONTROL & WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Existing Site Hydrology The existing site is rough graded, with a previously approved and constructed water quality/detention pond in place. The developable portion of the existing site is moderately sloped (slopes between 5-15%) and slopes down generally from the north and east sides of the property towards the southwest comer. At the west edge of the property is a wetland, which drains off site to the south See Section 4 of Appendix A (previously. approved TIR). Section 4 of the previously approved TIR contains the methodology used to size the approved, existing stormwater detention pond. 4.2 Developed Site Hydrology The project will create 40 residential lots with associated roadway, sidewalk, driveways, roof areas, landscaped yards, and a combined detention/water quality pond. All 40 lots will have new multi-family dwelling units. The 40 residential lots are modeled as 75% impervious. Additionally, a bank will be created on site, and will have an associated roadway, sidewalk, driveway, roof area and landscaped area. The previously approved and constructed detention/water quality pond is located in the southwest corner of the site. The detained runoff will be discharged to the west to the onsite wetland. The previously approved pond's developed areas are shown in Table 4.1. TABLE4.1 Annroved Develooed Pond Tributary Area SUBBASIN TOTAL IMPERV. nu AREA AREA(Ac} GRASS (Ac) (Ac) Whitman Court 3.28 2.57 0.71 TOTAL 3.28 2.57 0.71 The current site plan's developed areas are shown in Table 4.2. TABLE 4.2 Prooosed Develooed Pond Tributary Area SUBBASIN TOTAL IMPERV. nu AREA AREA(Ac) GRASS (Ac) (Ac) Whitman Court 3.52 2.42 1.10 TOTAL 3.52 2.42 1.10 See Figure 4.1 for a visual representation of the Developed Tributary Area See Section 4.4 for a comparison in flow rates between the previously approved site plan and the proposed layout 4-1 4.3 Performance Standards Performance Standards for flow control design use the KCRTS Methodology with hourly time steps as described in Appendix A: Section 4 and Section 4.4 below. To compare previously approved developed flowrates to proposed site plan flowrates, a runoff file for the proposed condition was created using the reduced KCRTS time series data set for the SeaTac Rainfall Region with a Correction Factor of 1.0. The site requires basic water quality treatment Water quality will be satisfied with a wetpond, which will be inside the combined detention/water quality pond. 4.4 Flow Control System KCRTS Pond Design According to the KCRTS pond design output in the approved TIR in Appendix A the developed flow rates (used as the inflow for the detention pond) are as follows: ::..0111 F,cgucucy Analysis l'ime Seri ,es t11 le: 7546dev. tsf Pro~ccL Locat..ion:Sca-Tac ---A11.nual Pc:ak Flow Rates--- Flow Rate Rank 'I·irr:e Of Peak !CFS) 0.686 6 2/09/0l 2,00 0.581 6 : /05102 16:00 0.821 l 12/08 I 02 18,00 0.653 7 6126 I 04 2:00 0.761 4 10/?.8/04 16,00 0. '/31 5 :118106 16:0G 0.951 2 10126/06 o,oo 1. :l6 1 :109/08 6,00 Comp1.:ted Peake -----Flow F1·equency Analyei5------- -P@aks Rank Return Prob !CFS) Pe~iod 1.36 1 100.00 0.951 2 25.00 0.021 3 10.00 0.161 4 5.00 0.711 5 3.00 0.666 6 2.00 0.653 7 1.30 o. sa: a 1. 10 1.23 50.00 0.990 0.960 0.900 . (i. 8-:J{I 0.667 0.500 0.231 0.091 0.980 The flow rates were obtained using the areas shown in Table 4.1, above. The flow rates for the developed area of the current project are as follows (using the areas shown in Table 4.2 above): Flow Frequency Analysis Time series File:dev.tsf Project Location:sea-Tac ---Annual Flow Rate (CFS) 0.685 0.567 0.821 0.624 0.748 0. 728 0. 907 Peak Flow Rates--- Rank Time of Peak 6 8 3 7 4 5 2 1 2/09/01 1/05/02 2/27/03 8/26/04 10/28/04 1/18/06 10/26/06 1/09/08 2:00 16:00 7:00 2:00 16:00 16:00 0:00 6:00 1. 37 computed Peaks -----Flow Frequency Analysis------- --Peaks --Rank Return Prob (CFS) Period 1.37 1 100.00 0.907 123 25.00 0. 821 10. 00 0. 748 4 5. 00 0. 728 5 3.00 0.685 6 2.00 0.624 7 1.30 0.567 8 1.10 1.22 50.00 0.990 0.!160 0.900 0.800 0.667 0.500 0.231 0.091 0.980 The current site plan's flow rates are all under the approved TIR's flow rates, except for the 100 year flow rate, which is currently 0.01 cfs over. This overage represents a 0.7% increase in 100 year flow rate, which is inconsequential. The 2 year, 25 year, and 50 year are all below the approved pondmR's flow rates. Therefore the existing approved pond design is valid for the current site plan. 4-2 Existing As Built Constructed Pond The previously approved pond was constructed and surveyed (as built) to determine total constructed detention volumes. The as built pond volume was calculated as 40,754 cubic feet According to the previously approved TIR (Appendix A), the pond volume required is 38,887 cubic feet. Therefore, the constructed pond is oversized by about 4.8%, and will perform as designed in the previously approved TIR. 4-3 Figure 4.1 Pond Tributary Area 4-4 4.5 Water Quality Faclllty According to the previously approved TIA in Appendix A the project site requires Basic Water Quality Treatment This water quality treatment will be provided by a wetpond in the combined detention/water quality pond. The previously approved TlR sized the required wetpond volume as 12,693 cubic feet. The land use has changed for the current site plan and has been resized using Table 4.2. The wetpond volume required for the current site plan is: A Vp/Va = 3 is calculated by dividing the wetpond volume (Ve) by the volume of runoff Na! from the mean annual storm. The sizing of wetponds is accomplished by determining the acreage of pervious and impervious land. Runoff volumes from pervious and impervious areas were determined by multiplying the acreage of each category by the mean annual storm (0.47 inches). Runoff factors of 0.25 for till grass areas and 0.90 for impervious areas were utilized. The sum of these values is the total runoff volume N,J. The required basin volume or the volume of the wetpond is determined by multiplying the Va by 3.0. Volume runoff from till grass = 1.10 Ac (Table 4.2) x 0.47 in. x 0.25/12 = 0.0108 Ac-ft Volume runoff from impervious = 2.42 Ac (Table 4.2) x 0.47 in x 0.90/12 = 0.0853 Ac-ft Total runoff volume Va= 0.0961 Ac -ft Total basin volume V8 = 0.0961 x 3 = D2fill_Ac -ft.= 12.545 cf The pond volume required for the current proposed site plan is less than the previously approved TIR's required wetpond volume, therefore the approved wetpond volume will perform as designed in the approved TlR. 4-5 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The stormwater drainage conveyance system will be sized to convey the 25 year design storm event and to contain the 100 year design storm event. A detailed Conveyance System Analysis and Design will be provided with the final TIR. 5-1 6. SPECIAL REPORTS AND STUDIES Following are the reports and studies referenced for the proposed development: • Approved Technical Information Report, by Barghausen, Inc, dated April 15, 2003 (see Appendix A) • Geotechnical Engineering Report, by Associated Earth Sciences, Inc, dated December 16, 2013 (see Appendix Bl 6-1 7. OTHER PERMITS The National Pollutant Discharge Elimination System (NPDES) permit will be prepared with the final construction plans. This project also requires the following permits: Building Permits Clearing & Grading Permits 7-1 a CSWPPP ANALYSIS AND DESIGN CSWPPP analysis and design will be provided with final engineering. 8-1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT The Bond Quantities, Facility Summaries, and Declaration of Covenant will be provided with the final TIR. 9-1 10. OPERATIONS AND MAINlENANCE MANUAL The Operations and Maintenance Manual will be provided with the final TIR. I 0-1 APPENDIX A Approved Technical Information Report Barghausen, Inc TECHNICAL INFORMATION REPORT Ribera/Balko Enterprises 2-Lot Short Plat Renton, Washington Prepared for: Ribera/Balko Enterprises September 2000 Revised August 16, 2001 Revised November 1 , 2002 Revised April 15, 2003 Our Job No. 7546 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES 18215 72NDAVENUESouTH KENT, WA 98032 (425) 25Hl222 (425) 251-8782 FAX 8RANCH0FACES + 0LYMPIA,WA + WALNUTCREEK,CA www.barghausen.com TABLE OF CONTENTS 1.0 PROJECT OVERVIEW 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 3.0 OFF-SITE ANALYSIS 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 6.0 SPECIAL REPORTS AND STUDIES 7.0 OTHER PERMITS 8.0 EROSION AND SEDIMENTATION CONTROL ANALYSIS AND DESIGN 9.0 BOND QUANTITIES, FACILITIES SUMMARIES, AND DECLARATION OF COVENANT 10.0 OPERATIONS AND MAINTENANCE MANUAL 7546.018.doc [JPJ/ath] 1.0 PROJECT OVERVIEW 1.0 PROJECT OVERVIEW The proposed project is located in the City of Renton on N.E. 4th Street near the intersection of N.E. 4th Street and Union Avenue N.E., just west of the United States Post Office. Currently, the project site is undeveloped, with a wetland and stream in the southwest comer of the site. The proposed project consists of the processing of a two-lot short plat on approximately 5.97 acres located along the south side of N.E. 4th Street in Renton, Washington. The project will include the construction of storm drainage, road way and utility improvements to serve the proposed lots as well as construction of wetland mitigation improvements and the tightlining of a portion of the drainage channel on proposed Lot L Future development of the individual lots will occur under separate land use applications and building permits. Drainage from the site will be conveyed to a proposed stormwater facility located on the southern portion of the property. The collected stormwater will be detained and treated, and released to the existing stream at the south of the property at the natural discharge location. The wetland and 25-foot wetland buffer limit construction on the western half of the site, as shown on the preliminary site plan. Development of the property will include filling less than 1/10 of an acre of wetland, while maintaining the proper setback distance from the remaining wetlands. 7546.018.doc [JPJ/athllep] King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner Ribera/Balko Enterorises Project Name 16400 Southcenter Parkway, #308, Address Seattle, WA 98188 Ribera/Balko Entemrises Short Plat Phone (206) 394-9601 Location Project Engineer Ali Sadr Township 23 Company Ban!hausen Consulting Engineers, Inc. Range 5E Address/Phone 18215 -72nd A venue South Section 15 Kent, WA 98032/ (425) 251-6222 ' ' . ', ', :· .. Part 3 TYPE OF PERMIT APPLICATION Part4 OTHER REVIEWS ANtl l'ERIIIITS .... . . Shoreline Manageme D Subdivision HPA D DFWHPA D nt 18] Short Subdlvlslor D COE404 D Rockery Structural D Grading D DOE Dam Safely D Vaults Other D Commercial D FEMA Floodplain D D Other D COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN .·... . Community Drainage Basin Lower Cedar River Basin . · . . > . •·.· • Parts SITE CHARACTERISTICS . ·.-. --.. --. _: .... \: . ·: D River D Floodplain D Stream 18] Wetlands D Critical Stream Reach D Seeps/Springs 18] Depressions/Swales D High Groundwater Table D Lake D Groundwater Racharge D Steep Slopes D Other 7546.018.doc [JPJ/athltep] Part 7 SOILS Soil Type Slopes Gravelly Sandy Loam I. 0 to 20 eercent D Additional Sheets Attached Part8 DEVELOPMENT LIMITATIONS REFERENCE 181 Wetland D D D D AddiUonal Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION 181 Sedimentation Facilities !81 Stabilized Construction Entrance 181 Perimeter Runoff Control 181 Clearing and Grading Restrictions 181 Cover Practices 181 Construction Sequence 181 Other Part 10 SURFACE WATER SYSTEM D Grass Lined Channel D Tank 121 Pipe System D Vault D Open Channel D Energy Dissipater 121 Dry Pond 181 Wetland 121 Wet Pond 181 Stream ·. • ·.·. . Erosion Potential Erosive Velocities Minimal . LIMITATION/SITE CONSTRAINT 25-foot buffer ··. ·.· .•' MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surface Remove and Restore Temporary ESC Facilities Clean and Remove All Silt and Debris Ensure Operation of Permanent Facilities Flag Limits of SAO and Open Space Preservauon Areas . . . Other--------------! . . . .. Method of D Infiltration Analysis D Depression KCRTS Compensation/ D Flow Dispersal Mltlgallon of Eliminated D Waiver Site Storage D Regional Detention Brief Description of System Operation Surface flow to catch basins, tightlined conveyance to wet/detention pond. Release at natural discharne location into stream 7546.018.doc [JPJ/ath/tep] Part 11 STRUCTURAL ANALYSIS Part12 EASEMENTSfTRACTS D Cast in Place Vault D Drainage Easement D Retaining Wall D Access Easement D Rockery> 4' High D Native Growth Protection Easement D Structural on Steep Slope D Tract D Other D Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated Into this worksheet and the attachments. T the best of my knowledge the information provided here is accurate. 7546.018.doc [JPJ/ath] J ·~ "• • " '<: • l :: _SJ - ' ! SOIL SURVEY King County Area Washington / ' · UNITED STATES DEPARTMENT OF AGRICULTURE Soil Conservation Service in cooperation with WASHINGTON AGRICULTURAL EXPERIMENT STATION Issued November 1973 ~. Ii. llf<J" ...... TNEN'TOf' Af,;IIICl/1.T\,'!U: S01LC0H8U~ .. 'TI~~VJCI: .... ___ ,. _ _,_,,, ........... .... _ ..... _ ..... __ .. -., ..... -. ... -. ..... ___ ..... ..__._ !.ii ! ,i ,k \c i ~JtQ.11 JUNO OOUffTY ARRA, W~'T(i,I ju,mlllQIJ~ ___ ......... -.-·--·-----__ , .. , ___ _ !:.."':!:' ... -.. __ _ 911DT-II GUIDE TO MAPPING UNITS For a full description of a mapping lU'l.it_. read both the d~scription of the mapping unit and that of the soil series to which the mapping Wlit belongs. See table 6, page 70, for descriptions of woodland groups. Other information is given in tables as follows: Acreage and extent, table I, page 9. Engineering uses of the soils, tables 2 and 3, pages 36 through 55. Town and country planning, table 4, page 57. Recreational uses, table 5, page 64. Estimated fields, t~le 7, page 79. Capability Wlit Woodland group Map sylmol Mapping unit Described on page Syni)ol Page AgB ~Age AgD J,kf AmB ,\mC Ml Bee BeD BeF Bh Br Bu a, Ea Ed EvB Eve EvD Ewe lnA InG Kp~ KpD Kse Ma Nee Ng Nk No Or Os ave OvD OvF Pc l'k l'u Py Rae RaD Rde RdE Alde?Wood gravelly sandy loam, 0 to 6 percent slopes---------- AldcTWood gravelly sandy loam, 6 to 15 percent slopes--------- Alderwood gravelly sandy loam, 15 to 30 percent slopes_-------- AldeTWood and Kitsap soils, very steep------------------------ Arents, Alderwood mateTi.~li Oto 6 percent slopes 1/---------- Arents, Alde:rwood material, 6 to 1S percent slopes-1/--------- A~nts, Everett material 1/-------------------------=----------- Beausite gravelly sandy 10am, 6 to 15 pen::ent slopes---------- Beausite gravelly sandy loam, 15 to 30 percent slopes--------- Beausite gravelly sandy loam, 40 to 75 percent slopcs--------- Bellingham silt loam------------------------------------------ Briscot si 1 t lo8Jll-------.. ----------·--------------------------- Buckley silt lo8Jll--------------------------------------------- Coastal beaches-------------M--------------------------------- Earlmont silt loam~~------------------------------------------ Edgewick fine sandy loam-------------------------------------- Everett gravelly sandy loam, 0 to 5 percent slopes---~-----~-- Everett gravelly sandy loam, 5 to 15 percent slopes----------- Everett gravelly sandy loam, 1S to 30 percent slopes---------- 'Everett-AldeTitiood gravelly sandy loams, 6 to 15 percent slopes------------------------------------------------------ Indianola loamy fine sand, 0 to 4 percent slopes------------~- Indimiola loamy fine sand, 4 to lS percent slopes------------- :ndianola loamy fine sand, 15 to 30 percent slopes------------ .~itsap silt loam, 2 to 8 percent slopes----------------------- Kitsap silt loam, 8 to 15 percent slOJles---------------------- Kitsap silt loam, lS to 30 percent slopes--------------------- Klaus gravelly loamy sand) 6 to 15 percent slopes------------- Mixed alluvial land------------------------------------------- Neilton veiy gravelly loamy sand, 2 to 15 percent slopes------ Newberg silt loam--------------------------------------------- Nooksack silt loam-------------------------------------------- Nonna sandy loam---------------------------------------------- Orcas peat---------------------------------------------------- Oridia silt loam---------------------------------------------- Ovall gravelly loam, 0 to 15 percent slopes------------------- Ovall gravelly loam, IS to 25 percent slopes------------------ Ovall gTavel]y loam, 40 to 75 percent slopes------------------ Pilchuck loamy fine sand-------~------------------------------ Pilchuck fine sandy loam-------------------------------------- Puget silty clay loam--------~-------------------------------- Puyallup fine sandy loam-------------------------------------- Ragnar fine sandy loam, 6 to 15 per<::ent slopes---------------- Ragnar fine sandy loam, 15 to 25 percent slopes---~----------- Ragnar-Indianola association, sloping: 1/---------------------- Ragnar soil--------------------------------------------- IndianoJ~ soil------------------------------------------- Ragnar-Indianola association, moderately steep: 1/------------ Ragnar soil-------------------q------------------------- Indianola soil------------------------------------------- 10 8 10 10 10 10 11 11 12 12 12 l3 13 14 14 15 15 16 16 16 17 16 17 17 18 18 18 18 19 19 20 20 21 21 22 23 23 23 23 24 24 25 26 26 26 IVe-.2 IVe-2 vre-2 VIie-i IVe-2 IVe-2 JVs-1 IVe-2 Vle-2: VIie-I lllw-2 IIw-2 !Ilw-2 VIIIw-1 nw-2 IIlw-1 rvs-1 Vls-1 Vle-1 vrs-1 IVs-2 !VS-2 Vle-1 IIIe-1 IVe-1 Vle-2 Vis-I VIw-2 vts-1 Ilw-1 IIw-1 !Jlw-3 V!l!W-1 Uw-2 IVe-2 VIe-2 Vile-I vtw-1 IVW-1 Illw-2 IJw-1 IVe-3 Vle-2 IVe-3 IVs-2 Vle-2 Vle-1 76 76 78 78 76 76 77 76 78 78 76 75 76 78 75 75 77 78 77 78 77 77 76 75 76 78 78 78 78 74 74 76 7B 75 76 78 78 78 76 76 74 77 78 77 77 78 77 3d2 3dl 3d] 2dl 3d2 3d2 3f3 3d2 3dl 3dl 3w2 3wl 4Wl 3w2 201 3f3 3f3 3!2 3£3 4s3 4S3 4s2 2d2 7d2 2dl 3£! 201 3f'I 2ol 201 3w2 3wl 3dl 3dl 3dl Zs 1 2sl 3W2 2ol 4sl 4sl 4sl 4s3 4Sl 4s2 U . .s. GOVERNMENT PRINTtNO OFFICE: 19~3 a -488-186 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.0 CONDITIONS AND REQUIREMENTS SUMMARY The proposed development has been designed using the 1998 King County, Washington Surface Water Design Manual (KCWSWDM) and the City of Renton Design Standards. These two criteria along with BMPs for erosion and sedimentation control will ensure that the applicable requirements pertaining to the site are utilized and addressed in the site improvement plan. The project will also fulfill Core Requirement Nos. 1 through 5 and 8 of Section 1.2 of the KCWSWDM. The following is a list of how the requirements are met for the proposed development. Core Requirement No. 1 Discharge at the Natural Location All of the collected storm surface water runoff will be collected by a series of catch basins and routed to the detention system/water quality pond to be treated and detained prior to discharge to the downstream. The discharge location is near the southern most property line into the drainage swale that traverses the property on the westerly side. The discharge elevation will be equal to the elevation of the drainage swalc at the property line. Core Requirement No. 2 -Off-Site Analysis Section 3 of this report includes a Level 1 Downstream Analysis and basin study for the proposed development. Core Requirement No. 3 Flow Control The proposed project will include design and construction of a detention and water quality pond to detain and treat the collected stormwater prior to discharging to the natural downstream path. The KCWSWDM will be used to design the drainage facilities. Level 2 Flow Control will be provided in accordance with the City of Renton. Core Requirement No. 4 -Conveyance System The conveyance system for the Ribera/Balko project will be designed and engineered according to the KCWSWDM, using the 25-year design peak flow storm event for all calculations. Core Requirement No. 5 Erosion Control and Sedimentation Control The proposed project will include clearing and grading of the existing property to provide the proper base for constructing approved buildings. Erosion control measures, including defining clearing limits, perimeter protection, traffic area stabilization, sediment retention, surface water controls and cover measures, will be utilized to prevent sediment transport from the site. Both temporary and permanent erosion measures will be implemented during and after construction. Core Requirement No. 8 -Water Quality As dictated by the City of Renton, Basic Water Quality is the requirement for this site. This requirement is met by providing a basic wet pond. 7546.018.doc [IPllath] 3.0 OFF-SITE ANALYSIS 3.0 OFF-SITE ANALYSIS Pre-Developed Conditions: The site is currently undeveloped. There is a wetland in the southwest portion of the site. Soils in the area are Alderwood soils, which are classified as till. The majority of the site is covered with brush. Post-Developed Conditions: The proposed project consists of the processing of a two-lot short plat on approximately 5.97 acres located along the south side of N.E. 4th Street in Renton, Washington. The project will include the construction of storm drainage, roadway and utility improvements to serve the proposed lots as well as construction of wetland mitigation improvements and the tightlining of a portion of the drainage channel on proposed Lot 1. Future development of the individual lots will occur under separate land use applications and building permits. All storrnwater from any new future impervious surfaces will be conveyed independently from the adjacent wetland to the southwest of the project site and stored in the proposed stormwater facility. The proposed pond will discharge to Maplewood Creek downstream of the wetland. Drainage from the proposed site will be conveyed independently of Maplewood Creek that currently flows along the western edge of the proposed site. An enhanced stream corridor has been proposed that bypasses flow through Maplewood Creek around the improved areas of the site. 7546.016.doc [JP//atbltep] LEVEL 1 DRAINAGE ANALYSIS Balko Renton Site N.E. 4th Street and 136th Avenue S.E. Renton, Washington Prepared for: Northwest Retail Partners, Ltd. 1904 -3rd Avenue, Suite 608 Seattle, WA 98101 October 2, 2000 Revised April 15, 2003 Our Job No. 7546 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES 18215 72NDAVENUESOUTH KENT WA98032 (425) 251-6222 (425) 251-8782 FAX BRANCH OFFICES • OLYMPIA, WA • WALNUT CREEK, WA www.barghausen.com TABLE OF CONTENTS 1.0 INTRODUL'TION/GENERAL INFORMATION 2.0 UPSTREAM DRAINAGE ANALYSIS 3.0 ON-SITE DRAINAGE ANALYSIS 4.0 DOWNSTREAM DRAINAGE ANALYSIS AND PROBLEM SCREENING 5.0 RESOURCE REVIEW A. Basin Reconnaissance Sunnnary Report B. Critical Area Drainage Maps C. Floodplain/Floodway FEMA Maps D. Other Off-Site Analysis Reports E. Sensitive Areas Folios F. SWM Division, Drainage Investigation Section Problem Maps 6.0 UNITED STATES DEPARTMENT OF AGRICULTURE SOILS SURVEY 7.0 WETLAND INVENTORY MAPS 8.0 DOWNSTREAM PROBLEMS REQUIRING SPECIAL AITENTION 8.1 Conveyance System Nuisance Problems (Type 1) 8.2 Severe Erosion Problems (Type 2) 8.3 Severe Flooding Problems (Type 3) 9.0 CONCLUSION EXHIBITS EXHIBIT A VICINITY MAP EXHIBIT B DRAINAGE AREA MAP EXHIBIT C ON-SITE DRAINAGE ANALYSIS EXHIBIT EXHIBIT D OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE AND PHOTOGRAPHS EXHIBIT E ASSESSOR'S MAP EXHIBIT F BASIN STUDY EXHIBIT G FEMA FLOODWA Y MAP EXHIBIT H SENSITIVE AREAS FOLIO EXHIBIT I WETLAND INVENTORY MAP EXHIBIT J DRAINAGE COMPLAINTS EXHIBIT K KING COUNTY SOILS SURVEY 7546.006.doc 1.0 INTRODUCTION A field visit was completed on September 22, 2000 in preparation of a Level 1 Drainage Report for the Rivera Property Assisted Living project. The project is located within a portion of Section 15, Township 23 North, Range 5 East, Willamette Meridian, King County, Washington, more specifically to the east of Union Avenue and along the south side of 4th Avenue N.E. The adjacent properties to the east and west are both zoned commercial. An existing building is located within the center of this site and is to be removed. This site is generally flat with elevations ranging from 401.3 feet down to 392.8 feet and gradually sloping from the northeast to the southwest comer. The site is vegetated with dense brush and tall grasses. Second growth forest lines the perimeter of the site. The southern portion of the site contains approximately 2 acres of wetland. Refer to the wetland exhibit in the sensitive areas map in the Appendix. The upstream flow is conveyed through our site, bypassing the detention and water quality facilities, exiting at the existing outfall. The proposed development will include construction of a 35,354 square foot multi-family assisted living project. The overall site is approximately 5.97 acres and is well suited for the proposed development. Detention and water quality facilities will be designed in accordance with the 1998 King County, Washington Surface Water Design Manual. The proposed drainage facility discharge location will remain the same as the existing condition. 2.0 UPSTREAM DRAINAGE ANALYSIS The overall project is gradually sloped with a low spot in the southwest comer and the high spot in the northeast comer. The site receives drainage from off-site property to the north. The surface water drainage flows under N.E. 4th Street through a 30-inch concrete pipe that discharges into an existing swale. The drainage bypasses the site by running through the swale from east to west along the north property line, eventually turning south and running along the west property line, before exiting the site around the middle of the south property line. 3.0 ON-SITE DRAINAGE ANALYSIS Upstream drainage discharges onto the site through an 18-inch CPEP and 30-inch concrete storm pipe. Drainage flows east to west through a ditch along the north property line. At the northwest comer the ditch turns south and runs along the west property line. The ditch becomes shallow and runs toward the middle of the site. It continues to run down the center of the site until exiting the site at the south property line. The existing site condition will be modeled as forest and pasture for detention calculations. Water quality treatment and detention will be provided prior to discharging on-site stormwater to the downstream. 4.0 DOWNSTREAM DRAINAGE ANALYSIS AND PROBLEM SCREENING Please reference the off-site analysis drainage system table and exhibit. The entire site is situated in the lower Cedar River drainage basin. After flowing through the site, drainage leaves the southern portion of this site and runs approximately 900 feet before tapering down to a smaller swale. Drainage then continues to flow southward for another 300 feet, then spilling into a drainage field. From there, drainage flows into approximately 100 feet of 12-inch storm drain line located at the opposite end of the drainage field. Finally it empties into a ravine, which is in 7546.006.doc excess of the 1/4 mile from the project site. During our field observation, we did not observe any evidence of erosion, overlapping, or capacity problems; however, a slight sediment deposition where the 30-inch storm drain empties into the existing swale on the south side of N.E. 4th Street was observed. A 12-inch pipe leaving the drainage field appears to be clear of any sediment. We were unable to locate and examine a 12-inch pipe running underneath Bremerton Place N.E. because of dense brush. The storm drain runoff continues on the downstream course into a large ravine and ultimately discharges into the Cedar River. 5.0 RESOURCE REVIEW The following is a description of each of the resources reviewed in preparation of this Level 1 Drainage Analysis. A. Basin Reconnaissance Summary Report This site is located within the Lower C',edar River subbasin within the Cedar River basin. A Basin Reconnaissance Summary Report can be found in Exhibit F of this report. B. Critical Drainage Area Maps To our knowledge, the project site does not lie within a critical drainage area. C. Floodplain and Floodway FEMA Maps Enclosed are the FEMA maps utilized for this analysis (Panels 981, Map No. 53033C0981). As indicated by the maps, the proposed project site does not lie within a floodway or a floodplain. The maps have been enclosed as Exhibit G in the Appendix of this report. D. Other Off-Site Analysis Reports A review of the basin study area and site investigation was conducted for analysis in preparation of this Level 1 Drainage Report. E. Sensitive Areas l<'olios After review of the King County sensitive areas folios it was found that our site does not lie within any sensitive areas. It should be noted that the project is located to the southwest of King County Wetland No. 150 and northwest of King County Wetland No. lOB. Please see the wetland inventory maps enclosed as Exhibit H in the Appendix of this report. Sensitive areas folio maps with the project site identified have been included as Exhibit H in the Appendix of this report. F. SWM Division, Drainage Investigation Section Problem Maps The drainage complaints for this area adjacent to or downstream from the project site are enclosed in Exhibit J in the Appendix of this report. 7546.006.doc There were complaints filed in the vicinity of the downstream path of the project. There are two complaints that pertain to the downstream drainage from our site. The first is PS-12, which can be found on the area map in Exhibit J. The complaint regarded fish passage through an 800-foot WSDOT culvert. This issue has been resolved (SWU 1995 CIP). The second complaint refers to flooding caused by inadequate culvert and pond size. This issue has been resolved (1995 SWU CIP/WSDOT SR-169 Project). Although the drainage flows that contribute to this problem come through the project site, we do not anticipate impacting the situation in a negative way, as detention facilities are required to limit discharge to that of the developed condition. 6.0 UNITED STATES DEPARTMENT OF AGRICULTURE SOILS SURVEY The United States Department of Agriculture Soils Survey for King County has been incorporated into this report and can be found in Exhibit K in the Appendix. In general, the project soils have been mapped as Alderwood gravelly sandy loam and Norma sandy loam. 7.0 WETLAND INVENTORY MAPS Wetland inventory maps were reviewed for this project. There arc no designated wetlands in the proximity of this project. 8.0 DOWNSTREAM PROBLEMS REQUIRING SPECIAL ATTENTION 8.1 Conveyance System Nuisance Problems (Type 1) Nuisance problems, in general, are defined as any existing or predicted flooding or erosion that does not constitute a severe flooding or erosion problem as defined below. Conveyance system nuisance problems are any nuisance flooding or erosion that results from the overflow of a constructed conveyance system for runoff events less than or equal to a 10-year event. Examples include inundation of a shoulder or lane of a roadway, overflows collecting in yards or pastures, shallow flows across driveways, minor flooding in crawlspaces or in heated garages/outbuildings, and minor erosion. After review of the drainage complaints provided to us by King County and field reconnaissance conducted by this office, it appears that our site does not incorporate any conveyance system nuisance problems, as defmed above. 8.2 Severe Erosion Problems (Type 2) Severe erosion problems are defined as downstream channels, ravines, or slopes with evidence of or potential for erosion/incision sufficient to propose a sedimentation hazard to downstream conveyance systems or propose a landslide hazard by undercutting adjacent slopes. Severe erosion problems do not include roadway shoulder rilliog or minor ditch erosion. This project does not anticipate and did not find any severe erosion problems as delineated in the above paragraph. Within the site there are slopes ranging up to 25 percent. 7546.006.doc 8.3 Severe Flooding Problems (Type 3) Severe flooding problems can be caused by conveyance system overflows or the elevated water surface of ponds, lakes, wetlands, or closed depressions. Severe flooding problems are defined as follows: • The flooding of the finished area of a habitable building or the electrical heating system of a habitable building for runoff events less than or equal to the 100-year event. Examples include flooding of finished floors of homes and commercial industrial buildings. Flooding of electrical heating systems and components in the crawlspace of a garage or home, such problems are referred to as "severe building flooding problems." • Flooding over all lanes of a roadway or severely impacting a sole access driveway for runoff events less or equal to the 100-year event. Such problems are referred to by King County as "severe roadway flooding problems." After review of the drainage complaints provided to us by King County, as well as field reconnaissance, it appears that our site does not contribute to downstream flooding problems along S.E. 133rd Street. Although the drainage flows through the project site, we do not anticipate impacting the situation in a negative way, as detention facilities are required to limit discharge meeting Level 2 Flow Control requirements. 9.0 CONCLUSION The downstream area for this project appears to have no major drainage related problems. Based on our field inspections it appears that there are no erosion problems. If designed in accordance with the City of Renton standards, we do not anticipate surface water runoff problems or exacerbation of existing problems. Mitigation should not be necessary, as current City of Renton storm drainage standards require detention release rates meeting Level 2 Flow Control. 7546.006.do< EXHIBITS EXHIBIT A VICINITY MAP VICINITY MAP A SOUR:CF: TH<">hlAS <iUIOC NORTH EXHIBITB DRAINAGE AREA MAP ,,i ,:., ' »,.. -, .. ~-- . ' /i''-"' \ ;: 'fJ _! ! \ l . ! \ Cont.our Int [ EXHIBITC ON-SITE DRAINAGE ANALYSIS EXHIBIT 1'"'60' Job Numb•r 7546 ShHt _1_ 0 ,_1_ ON-SITE DRAINAGE ANALYSIS EXHIBIT ~\ \\ \\ M \ \ 11 \\ l/ I\ 11 +--'Ir \ \ II -\\ --II ~ \\ /-··~ ,,...--u--, --~ l\1111.j,,p \\~===-.:~,!._ ______ :/.----.. -------. ---; .... ? __ .... ___ 11 / '\ ----~-=-------• . . ~-:,· I 'II / \\ I I " : I ,, : ,~· I ( i (; [~\ \ { ~ ,'~-~·::r\l !\I ,'\~'\" \ I I ! ,_ \ \ \ \ \ I '-~ ""/ / I I -.._ \ \ \ j! ~~~\:a.;_ \ ~--~ ::::-__:,c~ r,~_l_ \; ) ---. -.._ ----~ --........... ~ ----.:::::--..., 0-. ' ) -----.... .::----.::::----...... . ) -, ___ -----,, ~ --l--" ~..:::::-= I \ ~GHAc,~ 18215 72ND AVENUE SOUTH ,,,,'I' ~ KENT, WA 98032 .., .,. (425)251-6222 ; ": (425)251-8782 FAX 0 j .,. ' "',; "".,. CML ENGINEERING, LAND PLANNING, ( >-11v ,~~~ SURVEYING, ENVIRONMENTAL SERVICES GE:NG'~ --.... --~"'-"-"''~~"" = ~,/ ,-:"~Ir' II( I "----=~~~=:::: ~~! ~· I I I OMTgned NJM Drawn ___.M._ -JW,L "9pnwed J!!g!_ 0ote 0/26/00 "-"-"'"~~I.)/~·;'.\\~.\/ Scale: Hot1zontal i"•eo· Vertlccil N/A No. I 0ote I ey I Ckd. I "9pr. Revtslon Title: For: ON-SITE DRAINAGE ANALYSIS EXHIBIT RIBERA PROPERTY NE 4TH ST .... ~~-.,.., ~~ ,~.,., _, ___ ~ EXHIBITD OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE AND PHOTOGRAPHS OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Ilg Puget Sound Subbasin Name; Subbasin Number. SeeMap I TyJ>C' .i.,.dlow • ...,Je,-I Drainage basin, vegetation. cover, I 'I, I Pt I ConstrictiOD$, un<l<r "'P'city, ponding, I Tn1mtacy an:a, likdibood c{ problem, -. pipe, pond; siz.e, diamot<r, depth. type of sm&tive area. volume owrtoppiog, flooding. habitat or ovcrllow pe:thways, potential impacts surface area o,ganwn de&tmction, """1ring, bank sloo.gbing. sedimentation. incision.,. othtt UO&ian 1 I 18-incli SD !::pipe I I on .. site I I 2 I 30-inchSD Slight Sediment Deposition 3 I Channel I 2: I sides with heavy I I on~site I I ~wth, lO'wideX 5' deep 4 I Swale I 4'wide X 18" deep on-site none observed 5 Channel Z: I sides with heavy 0 · 900' n/a undergrowth, IO' wide X 5' deep 6 I Swale I lined with gravel and dirt, 10' I I 900'· 1,250' I none wide X l' dc;ep observed 7 I Drainage field I I I I 1,250' · 1,650' -lined with grass and gravel I none 400'longX 80'wide observed 8 I 12" pipe with grate 1,650' -1,750' none observed 9 I Ovcdl.ow 60" overflow with wiregrate none observed 7546.001 [EGL/au,] a> .fil .,.. ,E """'" u..i :z: .§ ~ ! 0 §_ ..Ill :g i '.:E :Q Jg ~ §, £ -~ (l) .g Q §_ Q .!: € ...:: B 0 '6 ~ 0 0 0 ~ ~ 0) C: ·c g ~ 8 § b <:-> Q --0 § € ~ 8 = _i;;; 00 i;; -i2 0 t ,g ! ~ ~ 8. r-f ~ 0) a. ~ '§ "t;; i f~ .£2~ = ~~ (_) 'a _E> a. 0 §} ~ 2 § ;g _§' :i 0 0 ;; :,/ ~ ! = §_ ]l .c 8' ~ .£: g, g -.:::, .g ~' .c ;g ,G <D -~ = ~ ~ ·e ..Q ~ LL J2 32 J!? Jg ~ (I) .B §' 0 ·c:J :g _g .c g, ~ g £; 0 2;l ~ i u.. Q) .I';; ·i a. ~ (.) <'-' ~ ! ~ 0 ~ I (.) c--, .6* 15 3= I i 0 EXHIBITE ASSESSOR'S MAP uLJO . KING COUNTY ASSESSOR ~;1------E:=1-I ,. ~ .. JJLI • •· .; (~T ~ SIT(/: . .I· -·1 . .• iJ'' ,. _., I ,; ~1 .. .. . ' .. • 2 ... u .• , ~tJ1'0,..a ,t!l,kP • .,.'170 ~ .. " • l. • '?-(., ?-, w .f~ ' ~· ';I ::,, " ~ 3 s c,; + e~ I s ~ I ~ \l'-'\ \ t :I 3 ~I>-6'~ l 1 J . ., ~ "" J --~, -';. -,-~-.. ' . .: ,. ~ ' .. " ... ('} t' ... .. " . Ll ~ z " .. ,,. y .,, ... ·?;-1,, 1 ' 0 ~ ~ "' I!: I\ ,, ASSESSOR'S MAP A NORTH S01.Jnc,;: 'fttOM ... S (;UIOC ) ,, EXIDBITF BASIN STUDY "'\, . \. \ RECONNAISSANCE REPORT NO. 13 LOWER CEDAR CREEK BASIN JUNE 1987 Natural Resources and Parks Division and Surface Water Management Division King County, Washington Department of Public Works Don LaBelle, Director King C.ounty E1tetulivc Tim Hill King C.ounty Council Audrey Gruger, District 1 Cynthia Sullivan, District 2 Bill Reams, District 3 Lois North, District 4 Ron Sims, District 5 Bruce Laing,. District 6 Paul Barden, District 7 Bob Grieve, District 8 Gary Grant, District 9 lyts. Planning and ~= Joe Nagel, Director Swface Water Management Division Joseph J. Simmler, Division Manager Jim Kramer, Assistant Division Manager Dave Oark, Manager, River & Water Natural Resources and Pads Divi,;ion Russ Cahill, Division Manager Bill Jolly, Aeling Division Manager Derek Poon, Chief, Resources Planning Section Bill Eckel, Manager, Basin Planning Program Resource Section Larry Gibbons, Manager, Project Management and Design &ction Contributing Staff Doug Chin, Sr. Engineer Randall Parsons, Sr. Engineer Andy Levesque, Sr. Engineer Bruce Barker, Engineer Amy Stonkus, Engineer Ray Steiger, Engineer Pete Ringen, Engineer Consulting Staff Don Spencer, Associate Geologist, Earth Consultants, Inc. John Bethel, Soil Scientist, Earth Consultants, Inc. P:CR • Contributing Staff Ray Heller, Project Mana~er & T earn Leader Matthcv.· Clark, Projec't Manager Robert R. Fuerstenberg, Biologist & Team Leader Matthew J. Bruengo, Geologist Lee Benda, Geologist Derek Booth, Geologist Dyanne Sheldon, Wetlands Biologist Cindy Baker, Earth Scientist Di Johnson, Planning Support Technician Robert Radek, Planning Support Technician Randal Bays, Planning Support Technlcian Fred Bentler, Planning Support Technlcian Mark Hudson, Planning Support Technician Sharon Oausen, Planning Support Technician David Truax, Planning Support Technician Brian Vanderouig, Planning Support Technician Carolyn M. Byerly, Technical Writer Susanna Hornig. Technical Writer Virginia Newman, Graphic Artist Marcia McNully, Typesetter Mildred Miller, Typesetter Jaki Reed, Typesetter Lela U:ra, Office Technician Marty Cox, Office Technician ) ) ( ) TABLE OF CONTENTS I. SUMMARY II. INTRODUCTION III. FINDINGS IN LOWER CEDAR RIVER BASIN A. Oveiview of Basin B. Effects of Urbanization C. Specific Problems 1. Drainage and flooding problems 2. Damage to property 3. Destruction of habitat IV. RECOMMENDATIONS FOR ACTION V. A. Reduce landslide hazards B. Reduce erosion and flooding C. Prevent future erosion and flooding with appropriate analysis, planning. and policy development D. -Stop present (and prevent future) damage to habitat by addressing specific problem• in stream systems • MAP APPENDICES: APPENDIX A: APPENDIX B: APPEDDIX C: Estimated Costs Capital Improvement Project Ranking Detailed Findings and Recommendations 1 1 2 2 4 s s 6 6. 7 7 7 8 8 11 A·l B-1 C-1 { L SUMMARY The Lower Cedar River Basin, in southwest King County, is unique in its development par. terns and the associated environmental problems that appear throughout the basin. Except for tho city of Renton and areas on the Cedar River Valley floor, most of the development in the .basin has occurred on the llpland platea11S. Most of this development is recent and primarily residential. In addition, the plateau is the site of numerous sand and gravel mining operations and, in the southern uplands, an abandoned coal mine. Peat is also being mined north of Otter Lake, In some areas livestock are being raised· on small farms; there are no major crop-related agricultllral activities in the basin. • The effects of development are most apparent where storm drainage is routed over the valley walls. Impcmous surfaces ou the plateau have incn:ased the :rate and volume of storm runoff, resulliog m substantial erosion, siltation, and flooding below. In addi- tion, erosion and ISiltation hll... damaged or destroyed habitat m many tn'butaries, threatening the survival of fish. Habitat and water quality throughout the basin are also threatened by the filling of wetlands and the presence of large amounls of domestic bash in som1> streams. The reconnaissance team noted that the Peterson Creek system bas so far remained in its natural, nearly pristine condition. Maintaining this quality should be a high priority in future basin planning capital project programs. Recommendations in the Lower Cedar River Basin include I) designing and constructing appropriately sized RID and other drainage facilities; 2) establishing stricter land 11Se policies regarding floodplains, wetlands, and gravel mining; 3) ooodllcting more detailed and comprehensive hydraulic/h)'drologic analyses of proposed developments; and 4) preventing damage to the mlllral d:rainage system. The field team also recommends 5) restoring the habitat of !iC>1:J31 tn'bularics ( e.g., cleaning gravels; revegetaiing stream banks, and diversifying slreambeds for •pawning and rearing) as well as 6) prolecting the nearly prisline quality of PetelSOII · Creek. IL INrR.ODUCUON: History and Goals of the Program P:LC In 1985 the King County Council approved funding for the Planning Division (now called the Natural Resources and Parks Division), in coordination with the Surface Water Management Division, to conduct a reconnaissance of 29 major drainage basins located in King Counly. The effort began with an initial investigation of three basins -Evans, Soos, and Hylebos Creeks -in order to derermine existing and potential surface watl'r problems and to recommend action to mitigate and prevent these problems. These initial investiga- tions used available data and new field obseivations to examine geology, hydrology, a.nd habits! conditions in each basin. Findings from these three basins led the King County Collncil to adopt Resolution 6018 in April 1986, calling for reconnaisoance to be completed on the remaining 26 basins. The Basin Reconnaissanre Program, which was subsequently established, is now. an important ele- ment of surface water management. The goals of the program are to provide useful data with regard to 1) critical problems needing immediate solutions, 2) basin characteris1ics for use in the preparation of detailed basin management plans, and 3) capital costs associated with the early resolution of drainage and problems.· The reconnaisoance reports are intended to provide an evahmtion of present drainage con- ditions in the County in order to transmit information 10 policymakers to aid them in developing more detailed regulatory measures and specific capital improvement plans. They are not intended to ascribe in any conclusive manner the causes of drainage or erosion 1 Lower Cedar River Basin (continued) problems; instead, they are to be used as initial surveys from which choices for subsequent detailed engineering and other professional environmental analyses may be made. Due to the limited amount of time available for the lield work in each basin, the reports must be viewed as desaiptive environmental narratives rather than as final engineering conclusions. Recommendations contained in each report provide a description of potential mitigative measures for each particular basin; "these measures might provide maximllm environmental protection through capital project constraction or development approval conditions. The appropriate extent of such measures will be decided on a case-by-case basis by County offi- cials responsible for revi~ing applications for permit approv;,ls and for chOosing among competing projects for public construction. Nothing in the reports is intended to substitute for a more thorough environmental and engineering analysis possible on a site-specific basis for any proposal. ID. FINDINGS IN LOWER CEDAR RIVER BASIN P:I..C The field reconnaissance of Lower Cedar River Basin was conducted in Janua,y 1987 by Robert R. Fuerstenberg. biologist; Bruce L Barker, engineer; and Lee Benda, geologist. Their findings and recommendations are presented here. A. Overview of Lower Cedar River Basin The lower Cedar River Basin is located in southwest King County and is Tl square miles in area. It extends sou th east from the mouth of the Cedar River on Lake · Washington to approximately river mile 14.0. The bou_nda,y to the northeast is marked by a ridgetop connecting the city of ReQlon to Webster and Franklin Lakes; the boundary lo the southwest runs along Petrovitsky Road to Lake Youngs. Renton is the only incorporated area in the basin. Other poplllarion centers include Failwood, Maplewood Heights, and Maple Valley. Excepc for the city of Renton, m05t of the residential concentrations are localed on the upland plateaus overlooking the Cedar River Valley. These upland developments are recent compared to the $Waller established communities on the valley floor. The basin lies within ponions of thre" King County planning areas: Newcastle in the no.nheast (which includes Renton), Tahoma-Raven Heights in the east, and Soos Creek (the largest of the three) in the west. Rural areas exist on the valley floor -on both sides of the Lower Cedar River, from approximately river mile 5.50 10 13.00. These an: limited 10 pastureland for horses, cows, and some sh.eep and several small "u-pick" fruit and vegetable farms. Similar areas are located on the southern uplands above the reach from river mile 5.50 to 7.00 and in the Lake Desire-Otter Lake area. The plateau is also the site of sand and gravel mining operations and, in the southern uplands, of the abandoned Fire King Coal Mine. Peat deposits exist west of Lake Desire and north and south of Otter Lake, and peat mining is being carried out north of Otter Lake. Present zoning allows for urban and suburban densities throughout much of the basin, panicularly on the upland plateaus and in the Cedar River Valley from its mouth to appoximately river mile 6.50. Population projections for the year 2000 in the three plannign areas containing the Lower Cedar Basin are over 311,000; an increase of 47 2 \ ( .1 P:LC Lower Cedar River Dasin (continued) percent from the present. Most of this growth .. ,11 occur in the Soos Creek Planning Area. Dominant geologit3I and geomo,phic fealules. The geology of the Lower Cedar River Basin is divecse. Geological formations exposed along the valley include sedimentary rocks, 11ndifferentiate<I older glacial dri(t, extensive gro,,nd moraine deposits, recent allllVium along the Cedar River, and landslide deposits along the river and its trib11- taries. The sedimentary rocks, composed of moderately dipping sandstones, con- glomerates, mudstones, and shales, are exposed locally along the cliffs of the Cedar River Valley near the mouth of the Cedar River. In addition, the Renton fonnation, composed of sandstones, mudstones, and shales with periodic deposits of cool, is also exposed along the lower ponion of the Lower Cedar River Valley. Undifferentiated glacial deposits found here are composed of three or more till sheets, glacio-fluvial sand and gravel, gtacio-lacustrine clay, and sand, and non-glacial sand, clay and thin peat. These lie over the sedimentary rock formations and are best exposed in cross-section along the cliff• of the main valley and major tributaries. The morphology of the Lower Ced.ar River Basin is dominated by the valley formed by the Cedar River. Valley walls are steep cliffs formed by landslides in glacial sedi- ments. A once extensive and meandering River, which created a wide valley floor as it cut its way westward, the Cedar today is diked for most of its length through the lower valley. A narrow but extensive band of landslide deposits exists along the steep cliffs of the main river and its major tributaries. The landslide deposits consist of deformed blocks of glacial sediments and colluvium derived from slides or mass flowage, such as landslides and debris flows. Recent alluvial deposits fill the valley and major tributaries. Small, composite, alluvial debris fans exist at the mouths of the largest tributaries. Closed depressions, principally in the uplands, have lacustrine and peat deposits. The Lo..-er Cedar River Valley has a high potential for erosion due to steep slopes and the existence of a clay layer that promotes soil failures. In addition, the confined nature of tributary channels between steep hillslopes promotes bank erosion during high flows. Numerous recenl landslides are evident along cliffs of many of the steep tributaries and along the main stem of the Cedar River. These llave been accelerated by the removal of vegetation and the routing of concentrated storm flows over steep slopes in areas where development .has occurred. Hydrologic and hydraulic characteristics. The Cedar River Basin is composed of a complex drainage network consisting of the Cedar River and 17 tributaries. The larger tributaries begin in lakes or wetlands on the bluffs and flow through relatively flat, stable channels to the edge of the Cedar River Valley, then plunge down to the valley floor through steep, erodible ravines. Tributaries of this type such as Tributary 0304 (with headwaters at Wetland 3111) and Tributary 0328 (which begins at Lake Desire), are found on the south side of lhe Cedar River. Another type of tributary collects surface runoff from urbanized areas, pastureland, and wooded areas. Tributaries 0302, 0307, and 0312 are examples of this type of tributary. They are intermittent ( depending on rainfall), shorter in length, flow through shallower channels that are steeper at the bluffs and transpon more material during times of 3 P:LC Lower Cedar River Basin (continued) high flows. Some of the worst problems located during field investigation (see Appendix C for a full listing) occur on this type of tributary. Catchments 5, 6, and 12 have very infiltrative soils. Urban developments hvae utilized R/D poinds to effectively infiltrate all urban runoff before it reaches the valley hillslopes. The infiltratec,1 runoff then reappears as spri!'l',S- Two large lakes (Desire and Otter), together with four smaller ones (Shady, Peteison, Webster, and Francis) Ile in the southeast third of the basin. Numerous large wetland areas exist in this section as "·ell. The field team identified 10 potential wetland sires that had not been previously identified in the Sensitive Areas Map Folio (SAMF). The system of lakes and wetlands in this area effectively buffers the high flows draining to these tributaries. Habilat dwacteriSlics. With few exceptions, usable fish habitat exists only in peren- nial streams (i.e., Trib. 0302, 0304, 0305, 0328, and possibly 0308). In other streams (e.g., Trib. 0303 and 0310), steep gradients preclude fish use. Steep gradients also reduce fish use in the pe.rennial systems (Cllfept for Trib. 0328). Habitat is in various stages of degradation in these systems; pools are being filled and gravels and debris shift regularly. In Tributary 0328 (Peteison Creek), however, habitat diversity is extensive, and the channel is not seriously degraded. At this location the field team observed at least three species of salmonoids. In general, the most divellSC and lea.st disturbed habitaf in a tributary system occurs i.n the large wetland areas in the southeast third of the basin. Usable habitat for anadromous fish is found in the low-gradient portions of streams where channels cross the Cedar River Valley floor. In these reaches, however, only spawning habitat is likely to be available, as the pools and woody debris necessary for successful rearing either do not exist or are quite limited. Excellent spawning and rearing areas exist where pools and riffles are extensive, instream cover and bank vegetation are intact, and diversity of habitat types is abundant. B. Elfeets ol UJbani7.ation in tbc Buill Aooding. erosion, and the degradation of habitat associated with development In the Lower Cedar River Basin are most apparent where development ha& e6minated vege- tation along the edges of the valley and where stormwater bas been routed down channels and swales. The removal of vegetation, such as trees, above and below the edges of valley walls, as well as the discharging of stormwater over the valley wall, bas resulted in tension. cracks and landslides that are endangering some houses. The sedi· ments from these failures are depositing in streams and on valley floors and damaging fish habitat and private property. Discharging stormwater from increased impervious areas into. steep tributary channels and swales is seriously destabilizing channels and valley wnlls; this in tum results in channel downcutting, bank erosion, and landslides. The sediments from these problems often degrade fish habitat and settle out on pri- vate property along the valley floor. Two serious instances of development-related erosion occurred during the November 1986 storm; 1) culverts rerouting the stream were plugged, causing the formation of a new channel that destroyed portions of roads on Tributary 0314; and 2) new, uncom- 4 Lower Cedar River Basin ( continued) pacted fill adjacent to new residences near collection point 5 was washed partly away during the storm, causing landsliding and gullying. Future problems will be similar to these, as commercial and residential developments increase flow rates and volumes by decreasing natural storage and infiltration. This is . expected to occur if wetlands on the upper plateau are ·encroached upon or lost ( e.g., on Tnb. 0304 at RM 2.30 and on Trib. 0304A at Rm 1.60). The preservation of wetlands and srreambank vegetation and the attenuation of storm flows are essential in this basin. C. Specutc: Problem.s ldentured The steep valley sideslopes through which streams pass and the often dense upland development result in a number of similar problems that repeat themselves throughout the Lower Cedar River Basin. The most significant of these are outlined and discussed below. 1. Drainage and flooding problems are often the result of 5CVCral conditions: a. Undersized culverts and inadequate entrance structures. The most notable area is on Tributary 0306 at. river mile .30, where a culvert here was blocked by debris carried downstream by the stream and caused erosion and flooding of Fairwood Golf Course. The blockage was compounded by the fact that the culvert was undersized; the problem will worsen as flows increase from upstream development. b. Serious instream erosion and subsequent downstream sedimentation. These have been caused by three main factors: 1) runoff from residential developments on the bluffs above the valley, 2) compacted pastureland due to livestock, and 3) runoff from impervious areas originating at gravel pits. These problems will continue and wor.sen until mitigative measures are taken. (See Appel)dix C for specific examples.) c. Undeni>.ed redwinelked streams.. Tributaries on the valley floor are too small to carry the increased flows originating in developed residential areas along the top of the bluffs. For example, Tributary 0302 at river mile .25, the channel along Maplewood Golf Cour.se, overtops and floods during storms. d. Construction in wetland and floodplain areas, Many of the wetlands on the south side of the Cedar River are peat bogs, and roads built through them continue to settle Cllch year, increasing the amount of flooding on the road. For example, the road crossing with Tributary 0328B north of Lake Desire will ex-perience more severe flooding as the road settles. e. Discharging of stormwater at the. top of ~ ban.ks. At river mile 2.20 on the Cedar River, a trailer park ( constructed on the edge of the cliff) discharges its drainage down the valley wall. Increased flows erode the steep valley, depositing sediments on the valley floor, blocking channels and causing flooding. These problems will eventually stabilize, but only after a large quantity of soil has been eroded. P:LC 5 P:LC Lower Cedar River Basin ( continued) 2. Damage lo p1opeily is being cau.sed by lhn:e factors: a. Landslides and potential landslides. Landslides are accelerated by the removal or vegetation on steep slopes in preparation for residential construction and/or by the routing of storm flows over hillslopes. For example, a Jarge landslide has already oceqrred in the front yard of a n,si. dence on the Cedar River at river mile 7 .80. b. Sedimentation (from landslides). Sedimentation and channel and bank ero- sion are damaging private property along the valley floor (Trib. 0299 and 0310). c. Flooding during IStOrlll5. Flooding has been brought on by the effects of development and associated changes to the natural drainage systems in the basin. (See 'B" above.) 3. Destruction of habilat is being caused by four conditiQns: a. Sedimcnlation of pools and riffles and cementing or p:av,:ls. These problems, the icsult of severe erosion and the transport of bedload material, have bee.n caused by upland developments in the basin and the presence of associated impervious surfaces, which increase the rate and quantity of surface runorr. Sedimentation and cementing of gravels in streambeds destroy natural spawning and rearing habitat. On Tributary 0307 at river mile .40 and Tributary 0305 at river miles .95, 1.20, and 1.70, recent high flows have eroded the streambed at least one foot, contributing to a serious siltation problem downstream. Heavy bedload transport is evi- dent in all systems of the basin except Tributary 0328. In Tributary 0303 at river mile .25, fine sediments are accumulating in gravels that may be used by resident fi.sh. In Tributary 0304 between river miles .95 and 1.20, pools are being fiUed by sands and gravels and rearing habitat is being rapidly lost. b. Cllannelizatioo of stream beds. Loss of habitat through channelization has occurred in all the major streams of the basin, but most noticeably in those reaches that cross the valley floor. These reaches lack liabitat diversity, reducing fish use for spawning and rearing. Channelization has damaged or destroyed. habitat in several reaches that were once heavily used by £ash; these include Tributary 0302 between river mile .30 and 40, Tributary 0304 between river miles .O~ and .18, Tributary 0305 between river mile .20 and .75, and Tributary 0328 from river mile 1.10 to 1.40. These systems cannot afford a further reduction of habitat and still remain viable fishery resour- ces. C. The aCC11111ulatioa or bash in stream beds. This problem occurs in close proximity to residential areas. Trash degrades water quality and is visually unpleasant. Tires, appliances, furniture, and other trash have been thrown into Tributary 0302 at river miles 1.00 and 1.10 and in Tributary 0303 at river mile .35. 6 __ ) ' ( \ ( \ d Lower Cedar River Basin ( continued) Wetland encroachment; Encroachment destroys habitat and eliminates natural water filtration and storage for surface runoff. Exam pies of this problem were observed on Tributary 0304 at river mile 2.30, Tributary 0308 at .80, and Tnbutary 0304A at rivet mile 1.80. Many wetlands have already been completely lost through filling. for example on Tributary 0306A at rivtr mile .55. Suspected viola.lions were forwarded to Building and Land Development for enforcement. IV. RECOMMENDATIONS FOR AcriON P:LC The primary recommendations for action in the Lower Cedar River Basin addresses current severe problems related to erosion, habitat destroction, and Oooding. Prevention of these problems will be accomplished by controlling locations and densities of new .development and providing adequate RID facilities for stormwater. A Reduce landslide hazards by: 1. Including sensitive areas ool previously mapped on the Sensitive Areas Map Folio (SAMF). See Appendix C for a full listing of sensitive areas. 2. Fstablishing building setbacl.s along cliffs and native growth protection easements along steep ravines. 3. Discouraging or eliminating the routing of stormwater over cliffs, unless adequate tightline systems can be constructed to convey Orn>-s in a safe, nonerosive manner to the bollom of cliffs. 4. Decreasiug peak flows by constructing larger RID facilities to lessen the landslide and erosion occurrence along tributary slopes. B. Reduce erooion and floodlag in the basin by implOYing surface water management: 1. Dlied the. Facilities Management Section of the Surface Water Management DiYision to evaluate· aislinl storm-detention and coaveyance facilities to deter- mine whether they are properly sized to meet current standards. Evaluation should begin wilh all single-orifice RID facilities. 2. Consider areas other than wetlands as regiooal st<>1111-<letention facilities. Tributary 0300 at river mile .42 is the site for a proposed dam, for example. 3. Utili,,e emting lower quality wetlands (those rated other than #1) as regional storm-detention facilities. Wetlands 3102 and 3142 could provide more live s1orage, for example. 4. Review channel and culvert capacity for co~g cmting and future runoff, and establish Ooodplain areas in regions of slight gradient for existing and future runoff conditions. 5. Promote the infiltration of surface waler througl, the use of retention facilities and open channels instead of pipes where the soil and slope conditions permit. Collec1ion poinls 5, 6, and 12 on plateaus have such soil conditions. 7 P:LC Lower Cedar River Basin { continued) C. ~t future problems of era;ion and tloodiog with appropriate analy.<is, planning, and policy dewlopment related to sulfaa: waler management: 1. c.ondm:t a detailed, IXllllpre.liensive hydnulk/h)'lrologie analysis of any proposed ~lopmenls to determine impacts on the drainage courses downstream. This is especially "!itical for areas on the · upper b)uffs and plateau, which drain pver steep, sensitive banks above the Cedar River. 2. Conduct a study of lhc impact of localing infiltration ponds utilized near the edge of the bluffs to determine their effect on seepage faces on the lower face of the bluffs. This might be accomplished with a computer-based numerical model of the groundwater flow. 3. Require the ligbllining of storm drainage down steep or sensitive slopes when they cannot be directed away from the ,lopes. This is done by piping the Oow down the slope and discharging it at the botlom with adequate energy dissipation. Many of the intermittent tributaries Oowing down the banks should be tightlined as urban development increases now to them. 4. Cooslruct new RJD ponds with filter bernL'l to improve water quality and reduce fine sediment loads. New RID ponds should have two cells with gravel-berm filters and vegetated swales at the inlet and outlet. Consider Tributaries 0304, 0304A, 0302, and 0303 as sites for this type of facility in order enhance waler quality, ( S. · Maintain natural -..:getalion oo streambaob and floodplains. This is especially important for relatively flat channels Oowing on the plateau before they reach the steep bluffs because these channels and their floodplains wiU attenuate flows during rimes of heavy runoff. 6. Maintain buffer an:as around w,:llands. Many of the tributaries on the south side of the Cedar River headwater at wetlands. These wetlands act as natural storage areas during storms. 7. Reevaluate King OJunty policy n,ganliog pemtittiog for graw,I mining on steep, sensitive slopes. 8. lnc:lude the city or Renlion in future interlocal agreemeols for planning and capi- tol improvemeni projects where city and county interests overlap. D. Eliminate present damage to habitat and J>l'C"CDI future damage by addJe&Sing specif"ic problems in the SIJealll systems. The following activities should be coordinated among King County, the Muckleshoot Indian Tribe, and State Departments of Fisheries and Game: 1. Reduce damaging: stonn °""" with greater detention volume and tower release rates at upstream developments. 2. Implement restoialion projects on Tributaries 0304 ( river mile .00-.20), Tributary 0305 (river mile .20-.80), Tnbutory 0303 (river mile .25-.35), and Tributary 0328 {river mile 1.10 -l.40): 8 j Lower Cedar River Basin J ( continued) ) a. On Tnoutary mot: Oean streambed gravels, add habitat and bed-control wei,s, and plant bank vegetation for shade. b. On Tributary 0305: Construct a new channel and move stream from road- side channel to its new location on a<!jacent lands. Implement a full restoraiion project to provide channel meandets, habitat structures, pool/riffle enhancement, streambed gravel replacement, and revegetation. c. On Tributary 0303: Move stream from present channel to a location further north, away from the roadside. If relocation is not possible, these minimum steps should be taken: Add habitat structure to existing channel with root masses, deflectors, boulder duste,s, and other features; revegetat~ channel banks with shrubs and small trees; enhance stream crossings with bottomless pipe arches, · d. On Tnln,tary 0328 (Peterson Cn:ek): Add habitat structure by replacing the straight, shortened channel with a more natural, meandering one; place habitat structures (such as root masses, deflectors, cover logs, and boulder clusters) throughout the channel; and revegetale banks wilh shrubs common to adjacent riparian zones (salmonberry, ninebark, or dogwood, for example). 3. Protect the PelcJson Creek i;ystem (Tnl>. 0328) in its pm;eot, near-pristine 51ate. This will include not only the restoration outlined in section A above, but also the adoption of land use management regulations to prevent future habitat destruction: a. Protect all existing .,,.,tlands within the subcatchments of Peterson Cn:ek.. Employ wetland buffei,; at least 100 feet wide without exception. b. Restrict development in the ailical headwater area ( drainage, babilat, water quality) bounded by Lake Deo:ire, Otter Lake, and Peterson Lake to rural densities. c. Designate and protect sm:amsidc muagement zones of at least 100 feet from the ordinary high-water marl< (OHWM) along the-main stem of the creek. Use 2.5 feet from the OHWM on tnl>utaries, d. Picsctvc floodplains and their foresas for dynamic retention of sediments and v.-ater. e. Restrict vegelation removal in 15tTeamside/wedand mm,agement 7DIICS. f. · Size RID facilities to sto,,, the 100-year storm at a two-to.f,ve-year release rate. Use the two-cell type of pond with a forebay, a gravel filter, and a vegetated swale outflow where feasible. g. Regulate more cl'*'ly all septic tank and dnin.f"ield installations, as well as maintenance schedules, particularly in the Lake Desire, Otter Lake, and Peterson Lake drainage areas. P~C 9 P:LC Lower Cedar River Basin ( continued) h. Work with the Slate Department of Ecology lo establish mioimum stream. flow requirements for Peterson Creek and Lake Desire tributary. 4. Develop aod promote public educalion and involvement programs for basin awareness. Work with schools, environmental groups, and the civic and business comDJunities to conduct educational and restoration programs. • 10 ., .. !" ... t. ' ~ I ·i ...... 1 ,..,-·~f:-:,-..,., \ 1·• '' i . ( \.. I "'",.,,·;,-_i,_,. ·--''·! r ;/ \J--·-, __ _,, -t 11 '~ \ . .! \~ ""\~ \ ! ' ': '"':-.,. '" ·1 ,: ': "i--"v-~--'~---,; 1 :)i :"·'·' ·_, ---... .. /. • .. 1 . :, '·-I---.:.:,~:.::--~='--.-··-. ·, . •• I I "'----= . rn : . I .............. )I ~ -·· ~ . \ '-, '•"'" LOWER CEDAR RIVER BASIN @ __,.. 0299 .3115 . . Basin Boundary Subcatchment Boundary Collection Point Stream Tributary Number Proposed Project 0 , 2 Milea f" \~ \,. I ----~.-·-· j .. ;.J'~·~ ,\;. !J ··.-_:_-~~ .. i'u" ··--·--'--',---. : ·, . \ -----·--·---\ .. '''\' . ·-·· ~ - ./ .1 \\··-..,_ I \ \ \ '· ·- N + '1 .!!;,~ J I ' '··;·· )-r-· . '--'· APPENDIX A ESTIMATED COSTS: PROPOSED CAPITAL IMPROVEMENT PROJECTS LOWER CEDAR CREEK BASIN • lndicateo l)l'Ojoct wu · idOflUiiod by Surface Water Management office prior to reconnafs,sance. NOTE, All project,, ore located on map ln~_udeg__jn thfs !!E!2!:!: Project Num!,er 3105* 3109* P:LC.APA Collect. Point 10 10 Proiect De,;cription Enhance 2200' of'Trib. 0305 from Cedar River to Elliot Bridge. Secure casements to wetland located in Cascade · Park and construct a berm at the outlet. Replace existing catch l>nsins with cont roJ struciures. Project should he justified !,y a 1,asin study. Wetland rated #2. (This wetland ,\,;n · require funher biological · evaluation before RID · design and c-onstruction.) Problem Addressed Mitigates flooding of King County park land. Detter utilizes wetland's storage capacity to addtesS peak flows from surroundi,:tg urban area. A-1 ·~· Estimated Costs and Comments $115,000 (NOTE: This project was proposed by Surface Water Management, is in the design phase, and will be constructed by 1989.) $186,000 Project Number 3111 (Wetland 3136) 3112 (Wctlund 3142) 3114* (Welland 3150) 3115 P:LC.APA .--~ . . . { ·-- Collect. f2m! 19 18 I'_roject Description Secure easements to outlet to Francis Lake and 1100' of channel from lake to SE 184th St. Construct a weir to raise lake level l', and enhance 1100' of Trib. 0317. Should be justlfled by a basin plan. Wctlnnd rated #1. (This wetland will require further biological evaluation before R/D dCl!ign and construction.) Secure ea.'ICmont for outlet to wetland and replace existing weir with a concrete-slotted woir; Should be justified by a basin plan. Wetland rated #2. (This wetland will require further biological evaluation before . RID design and construction. Secure easement to Welland 3150 and construct a containment benn and control structure at the outlet. Project should be justified by a bru;in plan. Wetland rated #2. (This wetland will require further hiological ewluation before RID design and construciton.) Install deterltion pond and 1,000' of tightlinc. Project is indepen- dently justifiable. · Prohlem Addressed Will provide additional storage to mitigate anticipate<! future i.ncrcased nows. Will provide additional storage for anticipated future peak flows. Addresses anticip11tcd increases in ·flow caused t,y d.;velopment. Mitigates severe erosion and flooding during times of high nows. . A-2 ~ Estimated Cos~~ and Comments $175,000 $117,000 $134,000 $361,000 -.. ----~~, J -- Project Collect. Estimated Costs Number Point Project Description Problem Addressed and Comments :\116 21 Raise existing road embankment Mitigates seasonal Oooding of Lake $73,000 2-4'. Project should be indepen-Desire Dr. SE caused by road bed dently justifiable. (Refer to settling in the peat bog. Roads Division.) 3117 16 [nslall 1,400' of tightfine, a Mitigates severe erosion, sediments $501,000 seditncnt trap, and 700' or channel deposited on County roads, and from Jones Rd. to Cedar River. Oooding during times of high Project i~ independently justi-flows. fiablc. 3118 lO Install 300' of 36: culvert, a new Will prevent blockage of culvert $87,000 inlet structure, manhole, and catch and the accompanying flooding and basin. Proje~"I is independently erosion of Fairwood GolC Course and justifial>le. mobile home park below. 31l9 4 Construct a detention dam and Project location is ideal because $159,000 control structure in a· deep it addresses flows from a large channelized section or Trib. resi<lential area before they reach 0300. Project is in<lependcntly the steep, sensitive area next to justifiable. the Cedar River. 3120 1.5 Construct a sedimentation pond and Mitigates flooding of residence and $163,000 1,000' of channel from Joncs Rd. to sediment deposition on Jones Rd. Cc<lar River. fcroject is indepen- den Uy justifiab c. P:LC.APA A-3 Project Collect. Number Point 3121 7 (Welland 3102) 3122 11 P:LC.APA Project Description Secure easement to wetland and con- struct a containment f>crm and concrete weir at oullet. Project should be justified by a basin plan. Wetland rated #2. Biological aSMSSment is needed to assure that .this·' project does not decrease habitat values. Purcha.w existing ponds-. on Fairwood Golf Course and expand to provide greuter now detentiOll. Project is independently justifiable. Pro),lem Addrcs.<;ed Addresses increased nows in Trib. 0304 and 0304A rrom residential developments. Mitigates fiooding and erosion downstream. A-4 Estimated Costs and Comments $371,000 $342,000 ) \ ) APPENDIX B CAPITAL IMPROVEMENT PROJECT RANKING LOWER CEDAR RIVER BASIN Prior to the Lower Cedar River Basin field =onnaissance, 12 projects had been identified and · rated using the OP selection criteria developed by the Surface Water Management (SWM) and Natural Re.sources and Parks Divisions. FoDowing the reconnaissance, 13 projects remain proposed for this area. They include eight n~, previously unidentified and .unrated projects. These displai:e seven previously selected projects, which were eliminated based on the consensus of the recon- naissance team. Projects were eliminated for several reasons: two sites were annexed by the city or Renton, tv;o projects were found to be unnecessary, two sites were categorized as #1 wellands (and are ineligible), and one project was determined to be infeasible. The previous SWM capital improvement project list for the Lower Cedar River Basin had an esti· mated cost of $2,710,000, while the revised list increases to an estimated cost or S2, 784,000. This 3 percent increase in estimated capital costs is due to the addition of projects after the reconnaissance. The follov.ing table summarizes the scores and costs for the C!Ps proposed for the Lower Cedar River Basin. These projects were rated according to previously established SWM Program Citizen Advisory Committee criteria. The projects ranked below are those for which the first rating question, ELEMENT 1: "GO/NO GO," could be answered affirmatively. Projects v.ith scores of 100 or higher can be considered now for merging into the "live" CIP list. RANK PROJECT NO. SCORE. COST 1 3122 103 $342,000 1 3118 90 87,000 3 3120 75 163,000 4 3109' 67 186,000 5 3121 65 371,000 6 3117 60 501,000 7 3115 60 361,000 8 3116 55 73,000 9 3114' 28 134,000 10 3111· 25 175,000 11 3112' 17 117,000 12 3119' 15 159,000 13 3105 12 115,000 TOTAL $2,784,000 • Projects proposed prior to the Reconnaissance Program P:LC.APB B-1 -~ • Al\ Items Hated here .,. located on final display maps ·-... .. ,.1 APPENDIX C DETAILED FINDINGS AND RECOMMENDATIONS · LOWER CEDAR RIVER BASIN In tho Offl-01 Surface Water Management BUIiding and Land Deve4Qprrteol and Basin Pfannlng. Trib. & Collect. Existing Anticipated Item• River Mile Point Category Prop. Proj. Conditions and Prot>lems Conditions and Problems 1 --5 Geology Gullying and landslides in Continued erosion. uncorripacted fill in new development near edge of steep hillslope. 2 --18 Geology Small landslide has formed None (natural failure). debris flow (11/86). · Sedimentation in yard of residence. ,3 0299 4 Geology Landslide,; in sedimentary Natural failure. RM 2.6 rock in cutbanks adjacent to railroad. 4 0299 16 Geology Drainage from re,;idential Increasing erosion. RM 9.65 area is re511lting in gullying in swale. P: LC.APC C-1 '--- Recommendations Recompact fill, revegetate, and drain adequately. None. None. Provide a<lequate R/0 to attenuate flows. Trib. & Collect. Existing Anticipated lli!!.\ River Mile Point Category Prop. Proj. Conditions and Problems i:;ondition_Land ProJ,lems _ Recommendations 5 0299 18 Geology Horse farm in uplands has Continued high erosion and Develop R/D . at horse farm RM 12.1 ·created extensive imper• sedimentation. to attenuate peak flows. vious svrfaces, resulting See Project 311S. in channel scour, bank erosion, landslides, and sedimentation at mouth of basin. Residence overcome with sediment. 6 -13 Geology Landslide terrain for sale Site of future mass erosion. Prohibit development here. by n:altors. High risk for Notify Building and Land landslides, flooding (from Development. Add area to springs), SAMF. 7 -7 Geology Large-scale landsides Natural process. None. ' adjacent to Cedar River d11e to springs and cutting or toeslopcs by streams. Appears to be natural. 8 -2 Geology Gllllying in valley wali Unknown. None. possibly from natural spring;,s. 9 -14 Geology Landslide debris flow from Existing tension cracks Revegetate hilfslope with :residem:c on SE 147th Pl, indicate fut11re instability. trees and shrubs. Renton. P: LC.A.PC C-2 ~- ; ' -· '-~ ~/ '··- Trib, & Collect. Existing Anticipated ~ River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendati9ns 10 ' 0299.lA 21 Hydrology 3116 Frequent flooding of Road located on top of peat Elevate the road 3-4' by RM .08 county road caused by low bog and will continue to filling on top of the road embankment. settle, aggravating Clooding present road embankment. problem, Also stabilize embankment. 11 0300 ·4 Geology Extensive channel and Problems will continue. Provide· adequate RID in RM .00-.40 bank eros.ion -and numerous uplands. (See Project landslides due to 3119.) development-related stormwater. 12 illQQ 4 Hydrology 3119 Development-related peaJc Increased erosion on Construct detention dam in Dows have caused sig-hillslopes below. deep, channelized reach of nificant bank erosion. Trib. 0300. 13 illQQ 4 Hydrology 3109 . CoUection point 4 has Degradation of Trib. 0300 Construct berm and standard RM 1.40 been nearly completely from RM .42 down&tream. This control structure at outlet urbanized. section is very · steep and to Wetland 3120 in .Cascade susceptible to erosion. Parle. 14 0302 6 Geology Channel downcutting and Will continue at same level Control siorm flows from RM .so bank erosion. or increase. uplands. 15 0302 6 · Geology Bank e.rosion (medium den-Increasing erosion with Provide adequate R/D in rui".so..1.00 1 sity) at meanders and increasing flow from devel-uplands as area develops. obstructions. opments. P: LC.APC C-3 Trib. & Collect. E>dsting Anticipated lli!!! River Mile Point Category Prop. Proj. Conditions and Prs,blems Conditions and Problems Recommendations 16 0302 6 Geology Gully erosion from broken None. Culvert has been None. culverts. repaired. 17 0302 6 Geology Severe gully erosion Continued erosion. Tightline flows to RM .60-.80 creating small valleys main stem. from daylight cu Ivens. 18 0302 6 Habitat Stream channeled along While fish now use this Add habitat diversity RM.35 golf coun;e road. No reach, Jack of habitat will ( e.g~ structures, overhead overhead cover. No habi-eventually reduc:e popula-vegetation). Gain· tat diversity. tions. easement to restore mean- ders, if possible. 19 0302 6 Hydrology Tn'butary drains down Problem will worsen as Construct detention dam RM.45 • steep bluffs on north development upstream upstream of golf course. side of Cedar River, continues. carrying debris and flooding Maplewood Golf Course. 20 0302 6 Habitat Water supply dam. Full As impoundment filL<;, storm-Dredge pond and maintain RM .SO barier to upstream water will flood over bank, it as sediment catch. migration. Impoundment Structure may fail. Is filling with sediment. 21 0302 6 Habitat Severe-gullying from right Will continue to erode until • Tightline downslope. RM .90 bank corregated metal reachos till layer. • Add velocity attenuator at pipe, Heavy sediment stream. delivery to stream. P: LC.APC C-4 --,-- '-J ,, •. ~,/ Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and_l'_@b~ins --Conditions and Problems ___ Recommendations 22 ' 0302 6 Habitat Trash in stream ( auto, Area adjacent to corridor, -Remove trash. RM 1.00 tires, appliances). will continue to collect -Distribute educational trash and debris. Further materials to streamside worsening of water quality, residents. sedimentation, erosion. • Cite violators, if problem per,;ists. 23 0302 6 Habitat Trash in stream. Water Area adjacent to corridor, • Remove trash. RM 1.10 quality problem, will continue to collect -Distribute educational unsightly. trash and debris. Further materials to streamside worsening of water quality. residents. .. -Cite violators, if problem persiSts. 24 0303 6 · Geology Extensive bank erosion in None. Increase RID volumes, slow relC8$: upper portions of tribu-rate to noncrosive levels. tary. 25 QW 6· Habitat Habitat suitable for resi-Sediments will eventually -Control stormwater volumes RM.25 dent fish. Sediment accu-cover gravels. Habitat and discharge rates from mulating. will become unsuitable for developments. fish use. -Manually clean gravels when necessary. 26 0303 6 Habitat Trash and litter in FurtI1er decreases in water -Remove trash and litter. RM .35 I channel affecting water quality. •. Distribute educational materials quality, causing erosion. to streamside residents. -Cite violators, if problem persists. P: LC.APC C-5 Trib. & Collect. Existing Anticipated full! River Mile Point Category Prop. Proj. Conditions ~nd_ Problems Conditions and Problems ~··--_ Re_comme(!dations 27 0304 7. Habitat Landslides contributing Sediment will continue to Maintain riparian corridor RM .40 sediment to channel. Heavy enter system until landslide with setbacks at least 50' deposition in pools. at stabilizes. Crom tOPli of bank$. obstructions, even in riffles. 28 illQ± 8 Habitat Hones have ac,:,:ss to Further decteases in water • Encourage residents to fence RM 2.10 stream, causing some bank quality, bank erosion likely. channel back IS' from ordinary deterioration and possibly big!,-wato~ mark. affecting water quality. • Limit .access to livestock to one or two points along stream. 29 0304 8 Hydrology Flooding caused by failing Problem will continue until Problem n:fcrred to Main- RM 2.30 ' RID at 176th St. & 146th outlet structun: is tenance section of Surface Ave SE. modified. Water Management Division. 30 0304 8 Habitat Encn:iachment occurring Wetland likely to be • Requin: encroaching fills RM2Ao along all boundaries of reduced slowly until it is to be removed. this headwater wetland. completely destroyed. Loss • Establish specific buffer of storage, filtratiQII, aro1,1nd this wetland. organic production, and • En!on:e sensitive areas wildlife habitat. ordinances and regula- tions. 31 illQ± 7 Geology Several gullies due to Problem will continue. • T,ghtline drainage. RM .80 daylight culverts; a few have iecent landslides. P: LC.APC C-6 --,, <"~"> ·--j -, ~·~··-. J . ... _..,,, Trib. & Collect. Existing Anticipated · llem River Mile Point Categoiv Prop. Proi. Conditions and Problems .~-<;:onditions ancl_ ~~blems Recomm~ndations 32 0304 7 Habitat Extensive riffle (to RM Gravels risk becoming • Enhance habitat by addi- RM .00 .15. Creek channeled. No cemented. Few resting areas tion · of woody debris in woody debris, little .bank for upstream migrating fish. stream. vegetation. Steelhead, • Revegetate bank. coho spawncrs here. • Enhance pool/rifne ratio. 33 0304 7 Habitat Debris jam may be a Debris will continue to • Selectively remove debris RM.20 partial migration barrier. accumulate. Channel will to allow fi.sh passqge. likely divert or jam will • Stabilize large woody fail, rel easi ns accumulated debris. sediment. 34 ~ 7 Habitat l>ebris jam. Bed drops 3' Debris will continue to • Selectively remove debris RM .62 over jam and sediment, accumulate. Channel will to allow fish passage. Conning anadromous likely divert or jam will • Stabilize large woody barrier. fail, releasing accumuJated debris. sediment. 36 0304 7 Habitat Water turbid; oily sheen Water quality will continue • Educate residents about RM .80 and odor present. Stonn to decline as runoff and how I!) maintain water quality. drains empty directly into waste enter stream. • Mark storm drains with stream. 'Dump no oil" signs. Emphasize recycling of oil. 37 0304A 7 Hydrology 3102 Existing forested wetland Additional storage could be Construct a proportional weir RM 1.30 I provides detention for utilized by constructing and benn at wetland outlet. Trib, 0304A and 0304 in benn and weir at outlet. Project could be used instead heavily developed area. This could be done to atten-of Project 3107 to rpeM'rve the uate increased peak flows #1 rated wetland (where project as upstream area develops. would be built). P; LC.APC C-7 Trib. & Collect. rtem River Mile Point 38 0304A RM .40 39 030S 40 030S RM 1.10 41 0305 RM 2.10- 1.75 42 030S RM 2.15· 1.75 P: LC.APC ' ·~ 18 10 10 10 10 Category Prop. Proj. Hydrology 311S Geology • Geology Geology Geology I Existing Anticipated Conditions and Problelll!___ C:::onditions and Problems _ Recommendations Runoff generated on top of Flooding will continue as -Construct detention pond bluffs on southwest side long as land wie remains the at top of bluffs. of Cedar River is causing same on top of bluffs or -Tigh!line drainage down severe bank erosion, until mitigating measures bluffs, then channelize it flooding and debris flows are taken. Runoff origin-to an existing ditch onto several residences ates from highly compacted alonpde SR 169, of valley floor. pastureland on uplands. -Prevent similar problems e!Sewhen, with land wie n,gulalio115, including provisions for preservation of vegetation buffers near tops of cliffs. Extensive bank erosion, Susceptible to increases Attenuate high flows. partly due to subsurface with increasing storm flow. clay layer and landslide topography. Local sewre bank Problem will continue. Existing rock-filled erosion. gabions arc deflecting flow. Extensive channel down-Continued erosion. Attenuate high flows with cutting and bank erosion. adcq,iate R/D. (RID currently exists.) Several gullies and asso-Erosion wil! continue. Tightline culverts. ciatcd landslides due to daylight culverts on steep slopes adjacent to chan- nels. C-8 _ .... -...... J -... ,..... Trih. & Collect. Existing Anticipated !!£!l!. River Mile Point <'.ategorv Prop. Proj. Conditions and Problems -Conditions _.~nd j'_roblcms_ R~commendation:;_ 43 0305 10 Habitat Madsen Creek in ditch along Potential for fuel entry in-Acquire 30' easement away RM .20 SE Jones Rd. Heavy silt; to creek. Further decreases from roadside. Construct road runoff; water quality in water quality can be ex-new stream channel. adversely affected. peeled. 44 0305 10 Habitat Creek in ditch along south Further decreases in water Acquire 30' easement away RM .35 side of SR 169. Heavy quality can be expected. from roadside. Construct inputs of oils, anti-Potential for autos to enter new stream channel. freez.es, heavy metals, channel. Lack of habitat. organic pollutants likely. Sand, silt from roadside •( of SR 169) enters also. 45 0305 RM .oo. 10 Hydrology 3105 Section of Tnl>. 0305, Aooding will continue • Construct and enhance 2200' of . 40 RM .00-.40 is experiencing (See Appendix A, Project channel through undeveloped extensive flooding. 3105.) King County Park Land. 46 ~ 10 Habitat Channelized along dri-Further siltation, water Acquire easement; move RM .50 veway; Jacks habitat quality degradation can be creek from driveway diversity. Driveway sedi-anticipated. Lack of habitat 10-lS'. Add meanders and ments enter channel, and precludes optimum salmonid habitat structures to oil placed on driveway use. increase diversity. enters stream. 47 0305 10 Habitat I Channelized tributary Little salmonid YSC Add structures to increase RM .65 lacks habitat diversity, anticipated. Spawning and diversity in stream, cover for salmonids. rearing suc'CCSS limited Manually clean gravels by Gravels compacted. (unless reach is restored). churning them. P: LC.APC C-9 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problem~--Conditions and P_robl_11_ms_ Becom_l!'lenda tion~ 48 0305 10 Habitat Good spawning riffles occur Increased flows may ca\lSe Control flows into system RM.90 here. 'lz-3' gravels, few gravel bar movement. from developed areas fines, not compact. High Suitable gravels may be Ypstreani. If. necessary, flows are moving material, transported downstream to add bed controls to hold h~r._ unusable areas for spawning gravels or "vce' struc- salmonids. tures to recruit them. 49 0305 10 Habitat Severe bank cutting and Further et011ion/scouring can Control high nows by RM .95 _ erosion occurs here. Iled be e~'J'ected. Channel increasing upper basin RID scouring evident. Reach deterioration will continue. facilities, lowering subject to high, rapid Aows appear to be generated discharge rates to stream. n-. at developments. so 030S 10 Habitat Much woody debris Debris jams will occur with Control ups_tream flows mf1.20 • movement and numerous greater frequency as fiows with greater RID volume, debris jams. Reach is increase. Sediments will lower discharge rates. subject to high, rapid build up and channel will Selectively remove debris. flows. divert. 51 ~ 10 Habitat Channel erosion, bank Further channel deteriora--Increase R/0 capacity. RM 1.70 failuRS, downcutting oc-tion may be expected. Silt, -Decrease discharge rates. curring. Reach subject to sand trans port to mam.,tem high, rapid flows. will increase. 52 0306 10 Geology Failure of manhole during Not applicable. Repair manhole. RM .40 11/86 storm has resulted in gully erosion. P: LC.AFC c.10 .. ,~ _, --- ·......._..:.. '--._,/ --"· Trib. & Collect. Existing Anticipated Ttem River Mile Point Category Prop. Proj. Conditions and Preble.ms Conditions and Problems __ Recommenda_tioM 53 ' 0306 10 Geology Channel downcutting, bank Erosion will increase. Clay Further increa.<;e in runoff RM .20 erosion and several layer in valley makes area should be attenuated; this landslides, due both from sensitive to landslides. is a sensitive channel. increased storm flows and development along edge. 54 0306 10 Geology Undersized culvert in arti· Possible fill failure: Lake Enlarge the corregated M!.30 ficial fill in golf course ponded behind culvert in metal pipe and/or threatens to build lake and in 1981 and threatened construct adequate trash possibly overtop bank. the fill. rack. Breach nood possible. < 55 0306 11 Habitat Channel subject to high, Further channel damage can Increase RID capacity, RM.25 damaging flows. Erosion be expected. Sediment decrease discharge rate. evident. transport downstream will continue. 56 0306 10 Geology Downcutting, bank erosion Will continue or increase in Attenuate storm flows. RM .30-.45 and landslides. future. 57 0306 Hydrology 3ll8 Trib. 0306 connects with Problem will worsen as Replace existing pipes RM .30 large tributary at manhole development up.stn,am with larger diameter pipes here. Debris from 0306 continues. (if downstn>am analysis clogs this manhole, cau.~ng allows for increased flows). severe erosion of Fairwood • Install· new inlet struc· Golf Course. t11res with trash racks. 58 ~ 11 Hydrology 3122 Existing small ponds on Area upstream is developing • Acquire easements for ponds RM 1.30 0306A arc overtopped and quickly, thus worsening the and additional area around ponds receive considerable silt problem. and construct detention pond. during high flows. The • Location is ideal for addressomg ponds arc located on peak flows before they reach FaitwOOd Golf Course. the sensitive Cedar Relver bluffs. P: LC.APC C-11 Trib. & Collect. Existing Anticipated ~ River Mile Point Category Prop. Proj. Conditions and Problems Conditions and _Problems __ Becommendl!_tions 59 ~ 11 Habitat Some usable habitat exists Further habitat deterioration • Increase R/D capacities. RM .25 for resident salmonids. likely. Qiannel erosion will • Decrease discharge rates. Water quality is poor. increase. • Encourage use of 2-cell Channel subject to high detention ponds, swales. flows. • Prohibit filling of existing wetlands, ponds in upper basin. 60 0307 12 Geology Extensive bank erosion at Increased erosion will • Mitigate development- RM .10-.40 all meanders and obstruc-result with increased flows. related high flows. tions (trees, cars) due • Provide adequate R/D, to increased flows Crom development. 61 Q;!QZ 12 Geology ' Stream eroding toes of Increasing erosion with • Mitigi,te development RM .10-.60 slopes resulting in increasing flows. related high fl~ landslide failures. • Provide adequate R/D. 62 0307 12 Habitat Stream channel pushed to Erosion will worsen as • Incroase RID capacity at RM.Jo one side o[ ravine for stream flows increase. all delivery points. roadway. High energy May threaten road bank at -Reduce release rate below system. Much bank cutting, toe of slope. channel scour level. sediment transport, debris movement. 6:1 0:I07 1:1 Hydrology Area on top of bluffs near Infiltration sites should Construct retention faci- RM.60 Trib. 0307 has excellent be used whenever po,;slble. lilies for new develop- infiltrative capacity. These would provide ground· mcnts in •!'C& at these sites. water recharge. P: LC.AFC C-12 ~-· ..... (, ( •' 1: \ ' -·~--:::" ·.~' ,.__, Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditiol!!_Jlnd _ Problem_s Conditions and Problems~-----Recommendations 64 0309 1S Habitat Subject to heavy, rapid Erosion, deposition will -Control storm flows RM .10 tlows. Channel erosion, increase. Sediments will upstceam. deposition bars migration. migrate downstream, creating Control volume and discharge a water quality problem. rates. 65 0310 1S Geology Sedimentation upstream from Continued sedimentation. • See "Hydrologic and hydraulic RM .60 culvert due to debris and characteristics" section in undersized culvert. New thls report. corregated metal pipe con- tlnues -to pass water through. 66 0310 15 Geology ,Severe erosion below Conlinued erosion and • Install energy dissipator RM .OS culvert, severe sedimen-sedimentation. below cotnlgllted metal pipe. talion in residence yard. -Excavate channel through yard where original channel was located. 67 Qlli! 15 Geology Road drainage forming gully Contim1ed erosion. Reroute drainage. Refer problem RM 1.50 adjacent to road; road bed to Roads Maintenance. in danger. 68 0:110 15 Habitat 3120 Corregated metal pipe is Problem will continue. Reinstall corregated metal RM .2.~ anadromous barrier. pipe at or below bed level. P: LC.APC C-13 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Prohlems Conditions and Problems Recommendations 69 0310 15 Hydrology 3120 Existing channel draining Frequ.,ncy and se.;..,rity of Constnict detention pond RM .40 off bluffs on north side problem will worsen as on upstream side of Jones or Cedar River, causing development on bluffs Rd. to trap sediments, and flooding of residences and . increases. enhance 1,000' or creek debris flows onto Jones Rd. from Jones Rd. to Cedar during peak flows. River. 70 0310 15 Habitat Corregated metal pipe Problems will oont.inuc and Remove new and old pipes; ·RM°.60 outlet approximately worsen as outCall velocities replace at lower level 9' above bed level. will scour bed and banks. with qveisized pipe with Complete banier to fish. Upstream has recent (11/86) trash rack. Old culverts at bed level deposition up to 4' deep. are plugged. 71 0311 13 Geology Gully erosion in drainage Continued accelerated ero-If possible, enlarge RID RM 1.70 • ,iwale due to outflow of sion. prior to its outlet in the wetland that partly seems wetland. to act as an RID facility. 72 0314A 16 Hydrology 3117 Severe erosion, flooding, Problem will be aggravated • Tightline drainage between RM.20 damage to County and as area above develops. detention ponds in gravel pit. private roads from • Construct detention pono;I increased ninoff from next to Jones Rd. to trap gravel pit operations on sediments. hillside. • Construct channel from Jones Rd. to Cedar River. 73 0314A/ 16 Geology Inadequate R/D, plugged Not applicable. See hydrology comment ~ I cu!wrt caused by exten-above. RM .J0 •. 40 sive channel and bank erosion and landslides. Water has cut a new channel. P: LC.APC C-14 ---.. ,--/ ( -·- Trib. & Collect. Item River Mile f2i!!! 74 , Qll1 75 76 77 RM 1.60 0320 RM 2.40 Qill RM .10 0382 RM .35 P: LC.APC 19 19 ~· Existing Category Prop. Proj. Conditions and Problems Hydrology 3111 Hydrology 3114 Habitat Habitat Francis Lake is only hydraulic control for Trib. 0317. Existing forested wetland with· targe amount of un- utilizell storage. Wetland ,currently detains flows on Trib. 0320. Salmonid parr in many pools. Large pools up to 1.15' deep. Some de posi- tion in pools, behind obstl'llctions. Salmonid use apparent from carcas.ses. Sockeye, Chinook spawners. Some sedimentation occurring. C-15 Anticipated Conditions an_d f_ro_blems Trio. 0317 flows through steep area downstream· oC lake. [f area around Francis Lake develops, increased peak flows could cause severe damage to Trib. 0317 in the steep region. If surrounding area urban- ize.,, this would be a good site to attenuate peak flows. Decrease in water quality with increasing develop- ment. Loss of habitat. Decrease in fish use. System is mostly in natural condition. As development increases, higher flows and worse water quality can be expected. ,J Recommendation.s Construct proportional weir at outlet. Enhance 1,100' from Francis Lake to SE 184th St. Construct containment berm and control structure at outlet of wetland (if bio- logical analysis permits). Establish and maintain adequate buffers, 100' from ordinary high-water mark or 25' from top fo slope break, whichever is greater .. -Maintain adequate stream corridor buffers. • Reduce discharge rates to pre-development levels. Prevent clearing. grading within buffers. Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems C<:>nditions and Problems Jl.ecommendations 78 0328 19 Geology Medium-density landslides None. · Limit "development in the RM .SO and high-density bank basin. erosion occurring due to natural causes. This indi- cates channel and valley sensitive to effects of development. (Sensitivity due to clay layer. Basin ho6ts some of best fish habitat in upper reachea.) 79 Qlli 19 Habitat Signmcant salmonid use Sedimentation from upstream Maintain leave strips RM .70 thro11ghout. Sockeye reach possible. Adjacent adjacent to stream at spawners, carcasses present. development will likely least. 100' ffOlll ordinary Cotto, stcclhead parr in reduce diversity and quality high-water mark. Restrict ' pools. Excellent habitat of habitat. IISC/development within this for spawning and rearing streamside management zone. (a redd site). Much diversity -most exemplary in basin. Channelized reach. Uniform May cause thermal problems Restore stream habitat 80 0328 19 Habitat channel, no habitat diver-as water temperatures rise. throughout: add structure, RM 1.10 sity. Heavy sand deposition. No useful habitat. diversity, bank vegetation, 1:40 Little overhead canopy or and canopy. Coat should be bank vegetation. bome by party(ies) who channelized this reach. 81 0328 19 Hydrology 3112 I Lake Peterson is small, Lake provides good peak flow Replace weir at outlet RM 1.40 open-water wetland with a attenuation and will become with a higher weir in weir at outlet. more important as upstream order to gain additional tributary area develops. storage. P: LC.APC C-16 .-· ~ EXHIBITG FEMA FLOODWAY MAP 1:ZSTH r z 0 z :, .... Kl :r .... ;:, 0 "' SOUTHEAST 2ND w ~ ~ z Q z :, SDllTHEAST w "' w :, ~I -<: i z 8 t z z w ::>.-a: 0 il.. u KING COUNTY 0 UNINCOJU'OMTIID AREAS (!) s,oon i'.: z ;;z 0 "' !::: '.:2: :::; w f- I~ a.. a: 0 u SOLJTHEAST 136TH STREET r.e ~ sou\'; 11-----CITY Of RENTON KING COUNTY KING COUNTY UNINCORPORATED AREAS 530071 &! i!l _, w ~ ~ "' ~ 0 , EXHIBITH SENSITIVE AREAS FOLIO t, toot.. show fhe r.trcams. Streams and 100- Year Floodplains ----c, ... 1 ••-• ..... •-•-• Class 2 (with salmonid&) ----C~ 2 (perennial; a.atmonid • • • • • use undelemtined) Class3 UnelMSffied ' \ Duwamish 4 , I ····,.,;-· ' ., . ., .,, Landslide Hazard Areas ·- Duwamish 4 ,. 'I tu. rt 0(.. - pte,c4:10f"d dony the tunnels. Coal Mine Ha2.ard Areas Duwamish 4 E • 1LI • __,ros1on ,, azaro 1\reas Duwamish 4 rti ~or uar. olas. suscl"tit'ible ther $elsmlc 1h m.ap are e ~edlrnenls; 1011. ,1 -1·! 'I:··· Seismic Hazard Areas Duwamish ,, ·> 4 -';11 lNetlands 'j .~ I-=-· -,1 Wetland$ -OpanWoler Basin Boundaries -... ~-fn Boundarie& su~ ,, ' \1~·.!!~ .;._2ib,j ' ~.-\ \ ;_.:., .. ~ 4 EXHIBIT I WETLAND INVENTORY MAP ) l NOTE: NO WETLAND AREA RECORDED Lower Cedar River Cedar River Basin EXHIBIT J DRAINAGE COMPLAINTS P.02/04 PS.a STONliWAY GRAVEL, CEl"lAR 32 FLOODING OF TilL"<c X. CR-+M I CR-:J..S CARCO THliA TER, RIVER SITED QCCUR DURING \ CITY HALL. RIVC:RA !'.XTREME Fl.000 EVENTS j APT$, AflD PRIVATr; (100~1'LOOD) HOMES ALONQ RIVER ~--;,.9 AIIJACENT TO CEDAR JZ NQ WOODY Rw""°AN X C/H-M ~ l;lf10Dl;l.L8 MAPLE RIVER VEGETATION DUE TO VALLEY HOMES DEV!il.OPMt:NT OF THE · RIGHT BANK AND A 8LIO! ON TI£ Ll:FT DANIC PS-10 MAPLEWOOD l'LAl' CEDAR i, HOM!:& 1nRC,;\TENED BY X X CR-~-M RIVER EROSION OF UPPER BANKS r.,-11 GINGER CREEK CEDAR 33 BLOCK.AG!! FOR SALMON X X X CR,4-M RIVER PASSAGE, PQOR WATrn . OUAUTY,ANDLOCAL~ED POOR OAAINAGE P&-1Z MAPLEWOOD CREEK CEDAR 31 FISH PASSAGE IS " X MAPU:'WOOD RIVER AFFECTEO BY AN 800' CRl!EKFISH WSOOTCULVERT UNDER PASSAGE SR.160 <;HANNEL PROJECT ($WU 1005C/Pi PS.13 MI\PLEWOOD GOLF CEDAR 31 CULVERTSia:RE-.,~v,S X X K MAPI..EWOuu COURSE RIVER FLOWS CAUSl"'8 CREEK FLOODING ON THE GOLF SEO/MEN r AT/ON COURSE. SEDIMENT BI\SIN PONDS ARE IHADEOIJAT!:, RECONST. TO TRAP FINE SEDIMENT PROJ.bC:T (1995 FROM UPSTREAM. SW!/ Clf'IWWOT SR·16g fflOJECTI ... ~., .. UPPEII. MAPLEWOoD CliDAR 31 ARFAS UI" LARGE X X (;fl-'-&! I CR~M i CREEK RIVSI EROSION HAVI! CAUS!o0 LANO flllDF.S AND GUWEO, ALIIO Dl!TECTEI) 11.!El'/\L IN THE ACUTI, ANti CHRONIC RANGE LOW6R Mii'l.EWOOD CEDAR HIGH FLOWS SE PS-16 EROSION. l'LOODING OF CREEK (DITCH l!EHIND Rl\ll!R HoMES ANP PROPERTY IN THI, PLAT OF THI! f'LA T OI' }MPl.EWOOO MAPl-&111000 T(l TIIE OCCURS DURING CEDAR RIVER) EXTREME STORM EVENTS. EXISTING CIJLVERT!; M/\Y BE UNDl:RSIZl:D AND PIPE CAf'ACITY TO THE CEDAR RIVf.R MAY BY IN/\ClE UA Tl:. , X X CR-4-MICR~M EASTfORK Cl!.llAR 3t ltlAl)EQUATE LOQ.LIZEt) P" .cg MAPLiWOOD t!W!K ,ul/eR STClRM CRAINAGE SY5TEM CAUSliS FLOOOING OF COLONY PARK Y/\ROS ANO HOMl!S HOMl;S. 6E U2ND, CAUSING S!PTIC TANIC t.QTII ANO 145TH URl!S . CR :Ill UNST AAU! RA VINE WAU.5 " -··-SUMl,WtFIElO CIU! Pli-11 CR..µ./ OGIONMAVHAVli X PS-18 TRlGGl:RED /\MAJOR. ) ' ~ -------..J ~1---....- •, l~---, I I I I I I ' I I I I I I 0 0 i 0 0 g g ~ ,ft .. .-! 0 SEP-29-201110 _.,. ,,,~ ,.,.. , .... r·---,; \ ~~:~ ~l \ -3 \.._ 0 1s:23 CITY OF RENTON PBPW I ' ' ' I I ~ ' ' _, \ ' ', .,, ,, •', '· .- .. '· ) ' () ,"·.--- ...-; '· ,\ l)l ·~-. . .. ;; "' -~ ....... '·' ; >: _,,_;~~." / .', ~E 14eod, St • ' r' ' ,. '"' EXIIlBITK KING COUNTY SOILS SURVEY KING COU1' (RE: ) ) DESCRIPTIONS OF lHE SOILS lnis section describes the soil series and map- ping units in the King County Area. Each soil series js described and then each mapping unit in that series. Unless it is specifically mentioned otherwise, it is to be assumed that what is stated about the soil series holds true for the ~apping units in that series. Thus, to get full information .about any one mapping unit, it is necessary to read both the description of the mapping unit and the description of the soil series to which it belongs. An important part of the description of each soil series is the soil profile, that is, the sequence of layers from the surface <lownw-ard to rock or other underlying matt"rial. Each series contains b~o Jescriptions of this profile. The first is brief a,ic..l in tcnns fmnilia.r to the Jayman. TI1c second, dct:iiJcll anJ in technical terms, is for scientists, engineers, :111J others w:ho need to make t?1orough :md p1·C'cis<' :-.tuJj(!'~ of .soils. Unless it j:, ,J:..hl.!r~.i:-L' :~::!t:,!, :.!:·.· ,·o!T·:~ gi::·'!: !nth,:-, ,lc:.cription:.; :1n~ thn:H• of :1 rnoi$t soi 1. :\~ mcntion~d in ti1\.~ ..;c..::tion ·i1oli" 111is Sun·cy Kos ~11.Je," not .ill mapping units arc members of a soil scl'ics. Urb,rn l:md, for ~x:unplc, docs not hclong to ~ soil series i but nevertheless, is listed in alplH•bctic onlcr along with the soil series. Following the 11;u11c o( c;;1..:h mapping unit is a spnbol in p~rcnthcscs. Thi$ symbol identifies the mapping unit on the Jct:Lilc<l soi] m;ip. Listed at the end of each dcsci-iption of a mapping unit is the capability unit and woodland group in which the mapping unit has been pl3ccd. 1'he woodland desig- nation and the ptigc for the description of each c.apabi Ii ty unit can be found by referring to the ''Guide to J.bpping Uni ts" at the back of this survey. The acreage and proportionate extent of each mapping unit arc shmm in table J. Many of the terms used in describing soils can be found in the Glossary at the end of this survey. nnd more de- tailed info:r:rrn:tior. about the terminology and methods of soil mapping can be obtained from the Soil Survey Manual (.!2.) . Alderwood Series 11te Alderwood series is made up of moderately well drained soils that have a weakly consolidated to strongly consolidated substratUJa at a depth of 24 to 40 inches. These soi ls are on uplands. They formed under conifers. in glacial deposits. Slopes are O to 70 percent ... The annual precipitation is 35 to 60 inches, most of which is rainfall, between October and May. The me.an annual air temperature is about SO~ F. The frost-free season is 150 to 200 days. Elevation rang.es from 100 to 800 feet. In a representative profile, the surface layer and subsoil are Very dark brown. dark-brown. ·and grayish-brown gravelly sandy loam about 27 inches thick. The substratum is grayish-brown. weakly consolidated to strongly consolidated glacial till that extends to a depth of 60 inches and more. 8 Alde:nmod berries, row are the most soils are used for timber, pasture. crops. and urban development. Tiley extensive soils in the survey area, ,' Alderwood ravell sandy lo3.DI, 6 to JS ercent ~lopes ---ln~s soil 1s rolling. Areas are irregular in shape and range from 10 to about 600 acres in size. Representative profile of Aldezwood gravelly sandy loam, 6 to 15 per<:ent slopes, in woodland, 4SO feet east and 1,300 feet south of the north quarteT corner of s:ec. 15 • T. 24 N. 1 R. 6 E.: Al--0 to 2 inches, very dark bro'k'n {lOYR 2/2) gravelly sandy loam, dark grayish brown (lOYR 4/2) d~y; weak> fine, granular struc- ture; slightly hart.I, friab1c, nonsticky, nonplastic; many roots; strongly acid; ahrnpt. Wa\'y boun<ljt·y. 1 to 3 inches thick. n2--2 to 12 inches, dark-hrow1l (HlYR 4/.\) !,l.1'3Vt.:!"llv sandy h1am, brown (lOYR S/3) Jry; 111odcratc,· mcdjl.Dn, suhangular blocky stn1ct11rc; slight]~- harJ1 friable, nonsticky, nonplastic; man}· roots; strongly aci<l; clear, w3V)'" boundary. 9 to 14 inc.hes thicL B3--12 to 27 inches, grayish-brown (2'.SY 5/2} gravel])'" ~andy loam, light gray (2.SY 7/2) Jry; many 1 mc<liw11, distinct mottles of light olive brown (2.SY 5/6); hard, friable, non- sticky I nonplastic; many roots; medium acid; abruptt wavy boundary. 12 to 23 inches thick. IIC&-27 to 60 inches, grayish-brown (2.SY 5/2), weakly to strongly consolidated ti 11, light gray (2.SY 7/2) dry; common, medium. distinct mottles of light olive brown and yellowish brown (2.SY 5/6 and IOYR S/6); massive; no roots; medium .i:cid. Many feet thick. Tile A hori~on ranges from very dark brown to dark brown. The B horizon is dark brown, grayish brawn. and dark yellowish brown. The consolidated C horizon, at a depth of 24 to 40 inches, is mostly grayish brown mottled with yellowish brown. Some layers in the C horizon slake in water. In a fe1,: areas, there is a thin, gray or grayish-bTOwn A2. hori2on. In most areas, this horizon has been destroyed through logging operations. Soils included with this soil in mapping make up no more than 30 percent of the total acreage. S<me areas are up to 3 percent th~ poorly drained Nol"lll3, Bellingham 1 Seattlei Tukwila, and Shalcar soils; some are up to 5 percent the very gravelly Everett and Neilton soils; and some are up to JS percent Alderwood soils that have slopes more gentle or steeper than 6 to 15 percent. Some areas in Ne..:& castle Hills are 2? percent Beausite soils, so~e northeast of Duvall are as much as 25 percent Ovall soils, and some in the vicinity of Dash Point aTe IO percent Indianola and Kitsap soils. Also included are small areas of Alderwood soils that have a gravelly loam surface layer and subsoil. l t ' ' up "!'18 •' tt all • } TABLE 1.--APPROXIMATE ACREAGE AND PROPORTIONATE EXTENT OF TilE SOILS Soil Alderwood gravelly sandy loam, Oto 6 percent slopes----------- Alderwood gravelly sandy loam~ 6 to IS percent slopes---------- Alde:rwood gravelly sandy loamt JS to 30 percent slopes--------- Alderwood and Kitsap soils, VCI)' steep--------------------------- Arents, A.lden<1ood material, 0 to 6 percent slopcs------------- Arcnts, AIJcn.ood m.."lter-ia.l, 6 to JS pei·ccnt .slopC!!>------------- _:,,rents, E\·crctt 1:iatc-ri.:il---------- :~i.:;:rnsite gran~l ly s:.rndy loam. 6 to lS pcrct.!nt slop...:s------------ :>causit:1! g1·.avel ly s;mJy lo3m, 15 to 30 pcrc<3nt slopt'$------------ 8e;;iusite gra\'elly santly loam, 40 LO 75 percent slop~s------------ Bellingham silt loam-------------- Briscot si.1 t loam----------------- Ouckley silt loam----------------- Coastal bea~hcs------------------- Earlmont silt loam-------":'-------- Edgewick fine sandy loam---------- Everett ,gravelly sanely loam, 0 to S percent slopes---------------- Everett gravelly sandy loam) 5 to IS percent slopes------------ Everett gravel l)' sandy loam, IS to 30 percent slopes------------ E\.·erett-Aldc1,.,ood gravelly sandy loams, 6 to 15 percent slopes--- Indianola loamy fine sand, 0 to 4 percent slopes------------------ Indianola loamy fine sand, 4 to 1S percent slopes--------------- Indianola loamy fine sand) IS to 30 percent slopes--------------- Kitsap silt loam, 2 to 8 percent slopes-------------------------- titsap silt loam, 8 to JS percent slopes-------------------------- Kitsap silt loam, 15 to 30 percent slopes-------------------------- Area Acres 22,000 165,170 14,280 39,000 3,SOO 6,000 700 ! , ,ovv \ ~, 700 S90 2,610 5,430 12,130 l, 105 1,140 2,340 5,500 15,700 6,300 8,405 2,670 2,600 500 5,000 6,550 4,270 Extent Percent 4.9 37.1 3.2 8.8 .8 1.3 .2 I.' .6 .2 . 6 I. 2 2.7 .2 • 3 .5 1.2 3.5 1.4 1.9 .6 .6 .l 1.2 l.5 l.0 Soil Klaus gravelly loamy sand, 6 to 1S·percent slopes---------- Mixed alluvial land------------- Neilton very gravelly loamy sand, Z to 15 percent slopes-------- Newberg silt loam---------~----- Nooksack silt loam-------------- Norma sandy Ioam---------------- Orcas peat---------------------- Oridia silt lOcllll---------------- Oval 1 gravelly loam, 0 to }S percent slopes---------------- Ov3ll gravelly loam, JS to 25 percent slopes---------------- 1 1.kall gya\"1..'ll}" lostm, -HJ tb l5 percent slopcs---------------- Pi !chuck Jo:uny fine s:md-------- Pilchuck fine sc.n<ly loam-------¥ Puget silty day loam----------- Puyallup fine sanoy loam-------- Ragnar fine sandy loam, 6 to IS percent slopes---------~--- Ragnat.-fine sandy loam, IS to 25 pc~ccnt slopcs------------- Ragnar-Indianol.;1 assoc.i a.t ion. sloping------~------~-------~- Ragnar-Indianola association, moderately stcep-------------- Renton silt loam---------------- Rivenvash----------------------- Salal silt loam----------~------ Sammamish si1t 1oam------------- Seattle JJ1Uck-------------------- Shalcar muck-------------------- Si silt loa~---·-------·-------- Snohomish silt loam------------- Snohomish silt loa111, thick surface variant--------------- Sultan silt loam---------------- Tukwila "'1Ck---------·-··------- Ul'ban land---------------------- Woodinville silt loam----------- Total----------------------- Area Acres 420 1,500 4,660 3,660 3,100 4,230 730 6,630 I, 780 3,S,10 l ,:!50 l ,flW 640 s, 130 4,840 500 8,110 1,150 5,040 3,700 560 790 8,650 1,220 1,750 2,100 500 3,580 1,730 10,650 2,800 445,500 Exterit Percent .1 .3 l.O .8 .7 J.O .2 I.S .4 .9 .3 .4 n I. 8 l. I .3 .1 1. 8 .3 1. l .8 'l .2 l.9 .3 .4 .s . I .8 .4 2,4 .6 100.0 9 Permeabi 1i ty is moderately rapid in the surface layer and subsoil and very slow in the substratum. Roots penetrate easily to the consolidated substra- twa where they tend to mat on the surface. Some roots enter the substratum through cracks. Water moves on top of the substratum in winter. Available water capacity is lowT RWloff is slow to mediumt and the hazard of erosion is moderate. lb.is soil is used for timber, pasture, berries, and row crops, and for urban development. Capability unit IVe-2; woodland group 3dl. Alderwood ravelly sand loamt O to 6 ercent ~ (AgB is soil is nearly level an undulating. It is similar to Alderwood gravelly sandy loam. 6 to IS percent slopes~ but in places its surface layer is 2 to 3 inches thicker. Areas are irregular in shape an<l range front JO acres to slightly more than 600 acres in size. Some areas are as much as 1S percent included Norma .. BcllinghaJ11, Tukwila, a11d Shalcar soils, all of which arc poorly drainctl; an<l some areas in the \·icinity of [nrnnLl:n-: arc :1s much .is IO pc-rcc-nt Auckley soi ls:. Runoff is slo"·, anJ the erosion hazard is slight. 111is Aldcrwood soil is used for timber, p.::isture,. berries, and row crops, and for urban dcvc]opment. Capability unit JVe-2; woodland group 3d2. Aldcri..,.ootl g1·ave1ly s:inlly loam, 15 to 30 percent slopes (AgD) .--Dept.h to the Sl1bstratum in this soil varies wi thil1 short distances, but is commonly about 40 inches. Areas are elongated and range from 7 to about 250 acres in size. Soils included with this soil in mapping roake up no more than 30 percent of the total acreage. Sane areas a.re up to 25 percent Gverett soils that have slopes of JS to 30 percent~ and some areas are up to 2 per-cent Bellingham~ NonM, and Seattle soils~ which are in depressions. Some areas, especially on Squak Mountain, in Newcastle Hills, and north of Tiger Mountain,. are 25 percent Beausite and Ovall soils. Beausite soils are underlain by sandstone, and Ovall soils by andesite. Runoff is medium, and the erosion hazard is severe. "Ole slippage potential is moderate. This Alderwood soil is used mostly for timber. Some areas on the lower parts of slopes are used for pasture. Capability unit Vle-2; woodland group 3dl. Alderwood and Kitsap soils, very steea (AkF).-- This mapping unit is about SO percent Al erwood gravelly sandy loam and 25 percent Kitsap silt loam. Slopes are 25 to 70 percent. Distribution of the soils varies greatly within short distances & About 15 percent of some mapped areas is an included, unnamed, very deep, moderately coarse textured.soil; and about 10 percent of some areas is a very deep~ coarse-textured Indianola soil. Drainage and penneability vary. Runoff is rapid to very rapid, and the erosion hazard is severe to very severe. The slippage potential is severeT These soils are used for timber. Capability unit VIIe-1; woodland group 2dl. JO Arents, Alderwood Material Arents, Alderwood material consists of Alderwood soils that have been so disturbed through urban- ization tha.t they no longe·r can be classified wit~ the Alderwood series~ 111ese soils, however, have many similar features. The upper part of the soil to a depth of 20 to 40 inches, is brown to dark-• brown gravelly sandy loam. Below this is a grayish- brown, consolidated and impervious substratum.. Slopes generally range from Oto 15 percent. Tilese soils are used for urban development. Arcnts. Alderwood material. 0 to 6 percent slopes (.lunR) .--In m_any areas this soil is level, as a result of shaping during construction for urban faci 1 it ies. Areas arc rectangular in _shape <md range from 5 acres to about 400 acres in si :.c. Representative profHc of Arents, Alden.'ood m~tcrial, Oto 6 percent slopes, i.n rm urb:in arc:1, J ,,oo foct west anJ 3SO fc'-'t south of thl! uurti11.!01st Lorncr of sec. :!S, T. ::!'S NT I R. 5 L: 0 to :?G inches. dark~brown {lOYR 4/3) gr:.nrd ly sandy loam, pale brown (lOYR 6/3) dry; massive; slightly hard, very friable. Jlon- sticky, nonplastic; many roots; medium acid; abrupt, smooth bound:1ry. 23 to 1!l i nehcs tl1ick. 26 to 60 inches, grayish-brown (Z.SY 5/2) weakly consolidated to strongly consolidated glacial till, light brownish gray (2.SY 6/2) t.lry; common, mcdiwn, prominent mottles of yellowish brown (lOYR S/6) moist; massive; no roots; medium acid. Many feet thick. 111c upper~ very friable part of the soil extends to a depth of 20 to 40 inches and ranges from dark grayish brown to dark yellowish brown. Some areas are up to 30 percent included soils that are similar to this soil material, b~t e!ther shallower or deeper over the compact substratum; and some areas are S to 10 percent very gravelly Everett soils and sandy Indianola soils. This Arents, Alderwood soil is noderately well drained. Permeability in the upper, disturbed soil material is moderately rapid to moderately slow, depending on its compaction during construction. The substratllll is very slowly penaeable. Roots penetrate to 3nd tend to mat on the surface of the consolidated substratum. Some roots enter the substratwn. through cracks. Water moves on top of j the substratum in winter. Available water c3pacity !.'• is low. RWloff is slow, and the erosion hazard is ~ slight. This soil is used for urban development. Ca- pability linit IVe-2; woodland group 3d2. Arents, Alderwood material. 6 to 15 percent ~ slopes (AmC) .--lhis soil has convex slopes. Areas are rectangular in shape and range from 10 acres to about 450 acres in size. i ~ ' ~ i I and grass on valley floors in the vicinity of North Bend. Slopes are Oto 3 percent. The annual pre- cipitation is 70 Lo 80 incJies, and the mean annual temperatw:e is about 50° F. The frost-free season . is about 150 days. Elevation ranges from 400 to 500 ,·.f.~ .. t.~ a representative profile, the surface layer is ---~~ dark grayish-brown to dark grayish-brown fine smdy lOtlJll that extends to a depth of about 34 ·inches. The underlying layers are black gravelly sand and gravelly sandy loam that extend to a depth ,f 60 inches or more. Edgewick soils are used for pasture. Edgewick fine sandy loam {Ed) .--This soil is ;Iig~tly convex or level. Areas are irregular in ;hapc and range from S acres to more than 300 acres in size. Slope is less tJ1.:tn 3 percent. Representative profile of Edgewick fine sandy to.iJII, in pasture, 1,430 feet cast and 1 1 000 feet 10uth of tJie west qu3rter corner of sec. JS, T _ 23 .~., R. S f,: ·,p--0 to ~, inches, V!.!ry J;.irk grayish-bn,1m (lOYk 3/'1:) fine s:.mtly loam, gr:iybh brown (lOYR 5/2) drr; i...·tJak. fine, granular structure; slightly hart.I, very fri.-.hlc, nonsticky, non- plastic; m<1ny routs; strongly acid; abrupt, smooth boundary. 3 to 11 inches thick. t:J--9 to 54 incJ1cs, dart grayish-brown (2.SY il/2) and olive-brown (Z.SY 4/4) fine san<ly loam, grayish brown (2. SY 5/2) tky; massive; soft, very friable, nonsticky, nonplastic; common roots; medium acid; abrupt, smooth boundary. 24 to 30 inches thick. JC2--34 to 60 inches, black (5Y 2/2), strati Ucd gravelly sand and gravelly sandy loam, grayish brown (2.SY 5/2) dry; massive; soft, very friable, nonsticky~ nonplastic; neutral. The C h01·izon ranges f.rom tlark grayish brown to vlive brown. TI1e content of gravel is as much as 10 percent in places in the A horizon and _the Cl · oriion. The IIC horizon, at a depth below 32 to 0 inches, ranges from dark grayish brown to black and fro• stratified sand to fine sandy loam that has gravel in some places. Soils included with this soil in mapping make p no more than IS percent of the to'tal acreage. :. .... -onie areas are up to 10 percent Nooksack and Si soils; sorae are up to 5 percent Pilchuck soils, :·"1ich occupy the natural levees along streams and he higher swells and undulations; some areas are -P to 2 percent the poorly drained Puget soils; and some are 1 percent the poorly drained Seattle soils. Permeability is moderately rapid. The effective ,oting depth is restricted by the gravelly sand -~bstratW11. lhere is a seasonal high water table at a depth of 3 to 4 feet_ Available water capacity ;c; moderate!)' high. Runoff is slow, anl the erosion 1zard is slight. lhe hazard of stream overflow is ~derate to severe. lhis soil is used for pasture. Capability unit TtJw-1; woodland group 2o1. t2llll0-73-2 Everett Series 1he Everett series is ~ade up of somewhat exces- sively drained soils that are underlain by very gravelly sand at a depth of 18 to 36 inches. 1hese soils f0I111ed in very gravelly glacial outwash de- posits, under conifers. Titey are on terraces and terrace fronts and are gently undulating and mod- erately steep. Slopes are Oto 30 percent. lbe annual precipitation is 35 to 60 inches, and the mean annual air te~perature is about 50° F. lne frost-free season ranges from 150 to 200 days. Elevation ranges from about sea level to 500 feet. In a representative profile, the surface layer and subsoil are black to browp, gravelly to very gravelly sandy loam about 32 inches thick. TI1e substratum extends to a depth of 60 inches or more. It is multicolored bhck to gr:iy very gravelJy sand (pl, l, left). f:.verett soils arc used for timber and pasture and for urban development. Everett g1·a,·ully sanJr !0;1m.,. o to S percent slopes (Ev1l).--TI1h: ncar1y level to very gcntlr undulating soi] is 011 tcrr;1c<'.S. Atc.15 arc irregular in shape and range from 5 acres to more than 200 acres in size. Representative profile of Everett gr,wclly sandy loam. 0 to S percent slopes, in forest. 450 feet we.st ;i.nd 2SO feet north of the southeast corner of soc. 30, T. 22 N., IL 7 E.~ 01--l to 3/4 inch, unJecomposcd roots, twigs, and moss; abundant roots. l to 2 inches thick_ 02--3/4 inch to O, black ·(toYR 2/1) ,decomposed organic matter; :ibundant roots. 3/4 of an inch to 1 1/2 inches thick. Al--0 to I 1/2 ind1cs, black (IOYR 2/1) sandy loam, gray (lOYR 5/1) dry; massive; soft, very fri- able, nonsticky~ nonplastic; many roots; slight1y acid; abrupt, distinct boundary. o to 1 1/2 inches thick. B2ir--l I/2 to 17 ind,es, dark-brown (7 .SU 3/4) gravelly sandy lomn, yellowish brown (lOYR S/4) dry; •assive; soft, very friable, non- sticky, nonplastic; many roots; slightly acid; clear, smooth boundaxy. 10 to 18 inches thick. B3--l7 to 32 inches, brown (lOYR 4/3) very gravelly sandy loam, pale brown (lOYR 6/3) dry; 111assivc; soft, very friable, nonsticky, nonplastic; many roots; medium acid; clear, wavy boundary. 8 to 18 inches thick. IIC--32 to 60 inches, black and dark grayish-brown (IOYR 2/1 and 4/2) very gravelly coarse sand, gray, grayish brown. and brown {lOYR 5/1 and S/3) dry; single grain; loose, nonsticky, nonplastic; few roots; medium acid. The A horiion ranges from black to dark gray. The Bir horizon ranges from dark brown and brown to dark yellowish brown and the 83 horizon frOtU brown to dark brown. lhe IIC hori~on ranges from black ~nd very dark brown to olive brown, and from very 15 } gravelly coarse sand to very gravelly loamy sand. Depth to the !IC horizon ranges from 18 to 36 inches .. Some areas are up to S percent included Alderwood soils. on the more rolling and undulating parts of the landscape; some are about 5 per~ent the deep, sandy Indianola soils; and some are up to 2S percent Neilton very gravelly loamy sands. Also included in mapping are areas where consolidated glacial till, which characteristically underlies Alderwood soils, is at a depth of S to 15 feet. Permeability is rapid. The effective rooting depth is 60 inches or more. Available water capac- ity is low. Runoff is slow,-and the erosion hazard is slight. lllis soil is used for timber and pasture and for urban development. Capability unit IVs-1; woodland group 3f3. Everett gravelly sandy loam, S to 15 percent slopes (J!vC) .--TI,is soil is rolling. Areas are irregular in shapct have a convex surfacer and range from :'.'5 :1crc::. to n,ori..• than ~00 ~1ct"cs in ~izc. Run- off i.t; sJo,\• to medium, and the erosion haz.ard is slight to moJ.crate. Soils iucluJ.cd witl, this soil in 1nappi11g 11wkc up no more than 25 percent of the total acreage. Some areas are up to 5 percent Alderwood soils, which overlie consolidateJ. glacial till; some are up to ::!O pcrc:C"nt Neil ton very gravelly lo,1my san<l; and some a.re about 15 percent included areas of Everett soils where slopes arc 1norc gentle than S percent and where they arc steeper than 15 percent. 111is Everett soil is used for timber and pasture and for urban development. Capability unit Vls-1; woodland group 3f3. Everett ravel] sandy loam, 15 to 30 ercent slopes EvD .--This soil occurs as long, narrow are3s, mostly along drainagcways or on short slopes between terrace benches. It is similar to Everett gravelly sandy loam, 0 to 5 percent slopes, but in :rnost places is Ste.lier and more gravelly. Soils included with this soil in mapping make up no more than 30 percent of the total acreage. Some areas are up to IO percent Alderwood soils, which overlie consolidated glacial till; some are up to 5 percent the deep, sandy Indianola soils; some are up to 10 percent Neilton very gravelly loamy sand; and some ~re about 15 percent included areas of Everett soils where slopes are less than IS percent. Runoff is medium to rapid, and the erosion hazard is moderate to severe. Nost of the acreage is used for timber. Capa- bility unit Vle-1; woodland group 3f2. Everett-Alderwood avelly sandy loams, 6 to 15 percent slopes (Ew .--1his mapplllg unit is a out equal parts Everett and Alderwood soils. 111.e soils are rolling. Slopes are dominantly 6 to 10 percent, but range fro• gentle to steep. Most areas are irregular in shape and range from 15 to 100 acres or more in size. In areas class~fied as Everett soils~ field examination and geologic maps indicate 16 the presence of a consolidated substratum at a-1 of 7 to 20 feet. lnis substratum is the same m; rial as that in the Alderwood soils. Some areas are up to 5 percent included N~~ Seattle, and Tukwila soils, all of which are poc drained. Runoff is slow to medium~ and the erosion ha2 is slight to moderate. Most of the acreage is used for timber. Cap~ ity unit Vis-I; woodland group 3f3. Indianola Series 1be Indianola series is made up of somewhat excessively drained soi ls that fomed under coni in sandy, recession.alt stratified glacial drift. l11esc undulating, rolling, and hummocky soils ar terraces. Slopes arc Oto 30 percent. The annu prccipi tation is 30 to_ 55 inch~s, ;in<l the mean annual air temperature is about 50° F. The fros free s~.ason is 1$0 to 2 JO days. Eleva ti on range frorn ;1hout :-.ca level to 1,000 feet. In a rcpreSL'ntativc profile, the upper .30 inc: is brm.n, JarJ.:. yellowish-brown, i3Jhl Jight olivc- Uro\ylJ loamy fine s;:mtl. This is u11Jcdain by oli· s.·u1<l that extends to :1 depth of 60 inches or mar, (pl. I, right). lntlinnola soils arc used for timber and for u: development. IncJianol:1 lo:i.mr fine sand, ,J to 15 p(!TCcnt sl1 (]nC) .--This undulating and rolling soil has com slopes. It is near the edges of upland terraces Areas range from S to more than 100 acres in sizt Representative profile of Indianola loamy fin1 san<l. 4 to 15 pt!rcent slopes, in forest, 1,000 fi west and 900 feet south of the northeast corner c sec. 32,. T. 25 N., IL 6 E.: 01--3/4 inch to 0, leaf litter. 82Ur--O to 6 inches~ brown (lOYR 4/3) loamy £inf sand> brown (lOYR 5/3) dry; massive; soft, very friable,. nonsticky, nonplastic; many roots; slightly acid; clear, smooth bowida1 4 to 8 inches thick. B22ir--6 to 15 inches, dark yellowish-brown (IOYF 4/4) lo3lly fine sand, brown (IOYR S/3) dry; massive; soft, very friable, nonsticky, non plastic; common roots; slightly acid; cleaT smooth boundary. 6 to 15 inches thick. Cl--15 to 30 inches, light olive-brown (2.SY 5/4) loamy fine sand, yellowish brown (lOYR 6/4) dry; massive; soft, very friablet nonsticky nonplastic; .. comrnon roots; slightly acid; gradualt smooth boundary. 12 to 17 inches thick. C2--30 to 60 inches, olive (SY 5/4) sand, light brownish grat (2 .SY ()/2) dry; single grain; loose, nonsticky, nonplastic; few rootsj slightly acid. Many feet thick. 'There is a thin, very dark brown Al horizon at the surface in some places. 1he B horizon ranges ) dry; massive; slightly hard, very friable; nonsticky. nonplastic; few roots; neutral. The A horizon ranges from very dark grayish brown to very dark brown. 1lte C horizon consists of layers of silt 103..111.1 very fine sandy loam, sandy loam, loamy sand, and sand; the thickness of each layer varies. Mottles occur at a depth below 30 to 40 inches in so•e places. Some areas are up to 2S or 30 percent inclusions of somewhat po9rly drained Briscot, Oridia. and Wood- inville soils; and some are up to 10 percent the poorly drained Puget soils. Total inclusions do not exceed 30 percent. Permeability is moderate. Tile effective rooting depth is 60 inches or more. A seasonal water table is at a depth of 3 to 4 feet in places. Available water capacity is high. Runoff is slow, and the erosion hazard is slight. The 1w.zard of strQ'..m over- flow is slight to severe. depending on the amount of flood proteLtion provided.. This soil is usod mostly fo1· 1·ow crops. Cap~hil- ity unit Ilw-1; woo<llanJ ~roup Jol. Nooksack Series The Nooksack series is maJe up of well-drained soils that formed in alluvium in river valleys. under a cover .of grass, conifers. and har<l1"ootls. Slopes are O to 2 percent. The il1UH!ill prccipi tation is 3S to SS inches. and the mean annual air tempera- ture is about S0° F. Titc frost-free season is about 190 days. Elevation rJl'lge.s from about sea level to SOO feet. In a representative profile, the soil is very dark grayish-brown. dark grayish-brown, and grayish- brown silt loam to a depth of 60 inches or more. Nooksack soils are used for row crops and pasture and for urban development. Nooksack silt loam {Nk).--Titis nearly level soil is in long, narrow areas that range fro~ S to about 300 acres in size. Slopes are less than 2 percent. Representative profile of cultivated Nooksack silt loam, 1,800 feet east and 500 feet south of the west quarter corner of sec. 4, T. ·24 N., R. 7 E.: Apl--0 to 2 inches, verY dark gr8yish-brown (JOYR 3/2) silt loam, grayish brown (lOYR 5/2) dry; few, fine, faint, dark yellowish-brown (lOYR 4/4) mottles; weak, thin, platy structure; slightly hard, very friable, nonsticky, non- plastic; many roots; slightly acid; abrupt, smooth boundary. 2 to 3 inches thick. Ap2--2 to 11 inches, very dark grayish-brown (lOYR 3/2) silt loam, grayish brown (lOYR 5/2) dry; ~eak, coarse, prismatic stnicture; slightly hard, very friable, nonsticky, nonplastic; common roots;· slightly acid; abrupt, smooih boundary. 8 to 10 inches thick. BZ--11 to 29 inches, dark grayish-brown (2.SY 4/2) silt loam, light brownish gray (2.SY 6/2) dry; weak, ~ediuro, prismatic structure and weak, 20 mediura 1 .subangular blocky st.ructure; hard friable, slightly sticky 1 slightly plasti•, d . "d l c, common roots; me llml aci ; c ear, 5mooth boWldary. 17 to 21 inches thick. · Cl--29 to 42 inches, dark grayish-brown (lOYR 41. and grayish-brown (2. SY 5/2) silt loaia a1d' thin lenses of very fine sandy loam., light brownish gray (2.5Y 6/2) dry; massive• sli ly hard> very friable, nonsticky~ nonP1ast1 comraon roots; slightly acid; clear, smooth boundary. 10 to 15 inches thick. C2--42 to 60 inches, grayish-brown (2.SY S/3) siJ loam: light brownish gray (2.5Y 6/2) dry; mass1.ve; hat"d, friable, stlcky, plastic· cc mon roots; medium acid~ ' ·ni.e B and C horiiuns are mostly silt loam and very fine sandy loam and have lenses of silty cl, loam and fine sandy loam. TI-te C horiion is dark grayish brown, grayish bro1,m, or dark brown, Some areas aro up to S percent included poorl) drained Puget soils; and some arc 10 to IS perce, the sorncb:'h:it poor]y tlraincJ Odllia anti Ildscot S{ Also includcJ with this soil in mapping are arcai of the poorly drained WooJinvillc siJt loam and , few areas of a \'looJinvillc silty cby loam. Incl soi ls make up no more than 15 percent of the~tot< acreage. Permeability is modcr.i:tc. 11,e effective rooti J.cpth is 60 inches or more. A seasonal water tat is at a depth of .) to 4 feet in places. Avail ab] water capacity is high. Runoff is slow, a.nd the erosion hazard is slight. Stream overflow is an erate to severe hazard. This soil is used for row crops and pasture a, for urban development. Capability unit Jiw-1; w1 land group 2ol. Norma. Series 1he Norma ser ics is made up of poorly drained soils that formed in alluvium~ under sedges, gr~ conifers. and hardwoods. n1ese soils are in bas: on the glaciated uplands and in areas al011g tt.e stream bottoms. Slopes are Oto 2 percent. lbe annual precipitation is 3S to 60 inches, and the mean annual air temperature is about 50° F. The frost-free season is 150 to 200 days. Elevation ranges from ~bout sea level to 600 feet. In a representative profile, the surface laye: black sandy loam obout 10 inches thlck. The sub: is dark grayish-brown and dark-gray sandy loam a1 extends to a depth of 60 inches or more. No:r11a soils are used mainly for pasture. If drained, they are used for row crops. Nonna sandy loam (No}.--This soil occurs ass· 2S to 300 feet wide. Slopes are less than 2 pe~ Areas are level or concave and range from l to .al 100 acres in size. Representative profile of Norma sandy loa11, i: pasture, 72S feet east and SO feet north of the south quarter corner of sec. 31. T. 20 N .• R. 7 E.: ,led ., C ,_ \" r OS ~nt. ,ut Ap·-0 to 10 inches, b13ck (IOYR 2/1) sandy loam~ dark grayish brown (lOYR 4/2) dry; moderate, fine, granular structure; slightly ha~d, very friable~ slightly sticky, slightly plastic; maJJ.Y roots; slightly acid; abTUpt, s~ooth boundary. 10 to 12 inches thick. B2lg--10 to 30 inches, dark grayish-brown (2.SY 4/2) sandy loam, light brownish_gray (2.5Y 6/2) dry; ts.any, medium. prom.ine_nt, yellowish-red (5YR 4/8) and brown (7.SYR 4/4) mottles, very pale brown (lOYR 7/4) and reddish yellow (7.SYR 6/8) dry; thin platy structure; hard, very friable, nonsticky, nonplastic; few roots; slightly acid; cle~r, wavy boundary. 19 to 24 inches thick. B22g--30 to 60 inches, dark-gray (SY 4/1) sandy loam, light gray (5Y 7/1) dry; COJ111110n, fine, prominent, strong-brmm (7.SYR 5/6) and reddish-)•~llow (7.5YR 6/6) mottles, yclJowish brown (!OYR S/S) .ind pale b.-own (2.SY 7/4) dry; massi\-c; slightly h:1rd, very fria},le, nonstid;y, nonplastic; fCl• toots; ;,,llghtlr ;1cid. ·nic A hod:on rangt!:::. frum hl.ld. to vl'!ry d:irk b 1•o.,,·n :tnJ i.:,; a:,; much :15 JS percent gr,wd. The H horizon commonly is sand)• loam that in places is sti·atified with silt lo:zi:i ;1n<l loamy .san<l. [t is as much as 35 percent gravel iu some place:;. l11c B horizon is mottled gray, ti.irk gray, and dark grayish bro,..·n. Some areas arc up to 5 percent inclu<lccl Seattle, Tukwila, .J.nd Shalc.ir solls; and some arc up to S percent Alde1,..,.ood and Everett soils, at the slightly higher elevations. In the area northwest of Auburn, in the Green River Valley~ there are areas of Norma soils that have an organic surface layer as thick as °\ 12 inches in some places. Also included arc small , areas of Norma soils th,1t have a silt loam surface layer. Pcnneability js modcratcl)' rapid. TI1c seasonal water table is at or near the surface. In drained areas, the effective rooting depth is 60 inches or nt0re. In undrained ~reas, rovting depth is restr~ct- ed. The available water capacity is moderately high to high. Runoff is slow. and the erosion hazard is slight. Stream overflow is a severe hazard in places. This soil is used mostly for pasture. Drained areas are used for row crops. Capability unit IIIw-3; woodland group 3w2. Orcas Series thick. The next layer is yellowish-red sphagnum peat that extends to a depth of about 60 inches. Orcas soils are used mostly as wildlife habitat·. Orcas peat (Or).--Tilis level or slightly concave. soil is in irregularly shaped areas that range frOll I 2 to about 10 acres in si~e. Slopes are less than l percent. Representative profile of Orcas peat, under wild cranberries, 600 feet north and 650 feet west of the east quarter corner of sec. 8, T. 24 N., R. 6 ET; Oil--0 to 6 inches, dark reddish-brown (SYR 3/2) sphagnum peat, very pale brown (lOYR 7/3) dry; soft, spongy; many roots; extremely acid; Clear, smooth boundary. 6 to 8 inches thick~ Oi2--6 to 60 inches, yellowish-red (SYR S/6, 4/6, 4/8) sphagnum peat, very pale brown (JOYR 7/4) dry; soft. spongy; few roots; extremely acid. TI1e Oil horizon ranges from dark reddish brown to rcddi~h black. Only slf~ht decomposition has oc- l:urrcJ. ·me Oi2 hori:.on is uniformly spha."!num pc.:Jt that ranges from dark rctldi:.h hrmm through yclloi..·- ish red to very pale hrot"11. Some areas mapped arc up to 20 percent includ~d Seattle a.n<l Tukwila mucks, ::rnJ some arc up to S per- cent. tl1c wet Bellingham soils. Permeability is very npid. There is a water tahlc at or close to the surface for several months each yc3r. In areas where the water table is c.on- trolle<l, the effective rooting depth is 60 inches or more. In undraiHed areas, :rooting depth is rcstrjcted. TI1e av~ilable water capacity is high. Runoff is ponded, and there is no erosion hazard. This soil is used mostly as wildlife habitat. Capability unit VIIIw-1; no woodland classification. Oridia Series The Oridia series. is ma.de up of somewhat poorly drained soils that formed in alluvium in river valleys~ Slopes are Oto 2 percent, The annual precipitation is 3S to 55 inches, and the mean annu- al air temperature is about 50° F. The frost-free season is about 200 days. Elevation ranges from about O to 85 feet. In a representative profile, the surface layer is dark grayish-brown silt loam about 9 inches thick. The subsoil is grayish-brown. dark grayish-brown~ and. gray silt· loam and si tty clay loam that extends to a depth of 60 inches or more. Oridia soils are used for row crops 8lld pasture and for urban development. Oridia silt loam (Os).--This gently undulating soil is in irregularly shaped areas. Slopes are less than 2 percent. Areas range from 10 to more than 200 acres in size T 'flle Orcas series is made up of very poorly drained organic soi ls that formed in sphagnum moss and smal 1 amounts of Labrador tea and cranberry plants. These soils are in basins on the undulating, rolling glaciated uplands. Slopes are Oto 1 percent. Annu- al precipitation is 3~ to 60 inches. and the mean· annual air temperature is about so~ F. 'llle frost- free season is 160 to 180 days. Elevation ranges from 100 to 500 feet. In a representative profile) the surface layer is dark reddish-bro~n sphagnum peat about 6 inches Representative profile of Oridia silt loam~ in pasture, 850 feet north~ 620 feet east of the southwest corner of sec. 12, T. 22 N., R. 4 E.: 21 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN The project will include the construction of storm drainage, roadway and utility improvements to serve the proposed lots as well as construction of wetland mitigation improvements and the tightlining of a portion of the drainage channel on proposed Lot 1. Future development of the individual lots will occur under separate land use applications and building permits. Level 2 Flow Control detention criteria will be used for the detention requirement for the stormwater collected and routed to the detention pond. The basic water quality menu will be used to engineer the water quality facility according to the King County standards. The detention facility is located in the southernmost portion of the site and will discharge at the natural location on the downstream path. 7546.018.doe [JPl/alh] KCRTS Command INFORMATION about this program KCRTS Command CREATE a new Time Series Production of Runoff Time Series Project Location: Sea-Tac Computing Series 7546pre.tsf Regional Scale Factor: 1.00 Data Type: Reduced Creating Hourly Time Series File Till Pasture Loading Time Series File:C:\KC_SWDM\KC_DATA\STTP60R.rnf 3.28 acres Total Area 3.28 acres Peak Discharge: 0.396 CFS at 6:00 on Jan 9 in Year 8 Storing Time Series File:7546pre.tsf Time Series Computed KCRTS Command Enter the Analysis TOOLS Module Analysis Tools Command Compute PEAKS and Flow Frequencies Loading Stage/Discharge curve:7546pre.tsf Flow Frequency Analysis Time Series File:7546pre.tsf Project Location:Sea-Tac Project Location: Computing Series Regional Scale Factor: Frequencies & Peaks saved to File:7546pre.pks Analysis Tools Command RETURN to Previous Menu KCRTS Command CREATE a new Time Series Production of Runoff Time Series Sea-Tac 7546dev.tsf 1. 00 Data Type: Reduced Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG60R.rnf Till Grass 0.71 acres Impervious Loading Time Series File:C:\KC_SWDM\KC_DATA\STE160R.rnf 2.57 acres Total Area 3.28 acres Peak Discharge: 1. 3 6 Cl:'S at 6:00 on Jan 9 in Year 8 Storing Time Series File:7546dev.tsf Time Series Computed KCRTS Command Enter the Analysis TOOLS Module Analysis Tools Corrirnand Compute PEAKS and Flow Frequencies Flow Frequency Analysis Time Series File:7546dev.tsf Project Location:Sea-Tac Loading Stage/Discharge curve:7546dev.tsf Frequencies & Peaks saved to File:7546dev.pks Analysis Tools Command Compute flow DURATION and Exceedence Loading Time Series File:7546pre.tsf Computing Flow Durations Durations & Exceedence Probabilities to File:7546target.dur Analysis Tools Command COMPARE Flow Durations CANCELLED Analysis Tools Command RETURN to Previous Menu KCRTS Command Size a Retention/Detention FACILITY Edit Facility Loading Time Series File:7546dev.tsf Time Series Found in Mernory:7546dev.tsf Saving Retention/Detention Facility File:7546stream.rdf Starting Documentation File:c:\kc_swdm\7773\3-l-02\7546stream.doc Time Series Found in Memory:7546dev.tsf Edit Complete Retention/Detention Facility Design Flow Frequency Analysis Time Series File:7546pre.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Rate Rank Time of Peak (CFS) 0.231 2 2/09/01 18:00 0.086 7 1/05/02 16:00 0 .211 3 2/28/03 3:00 0.022 8 3/24/04 19:00 0 .118 6 1/05/05 8:00 0.197 4 1/18/06 16:00 0.190 5 11/24 / 06 4:00 0.396 1 1/09/08 6:00 Computed Peaks -----Flow Frequency Analysis------- --Peaks Rank Return Prob {CFS) Period 0.396 1 100.DO 0.231 2 25.00 0.211 3 10.00 0.197 4 5.00 0.190 5 3.00 0.118 6 2.00 0.086 7 1.30 0.022 8 1.10 0.341 50.00 0.990 0.960 0.900 0.800 0.667 0.500 0.231 0. 091 0.980 Flow Frequency Analysis Time Series File:7546dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak -Peaks Rank Return Prob (CFS) (CFS) Period 0.686 6 2/09/01 2:00 1.36 1 100.00 0.990 0.581 8 1/05/02 16:00 0.951 2 25.00 0.960 0.821 3 12/08/02 18:00 0. 821 3 10.00 0.900 0.653 7 8/26/04 2:00 o. 781 4 5.00 0.800 0.781 4 1.0/28/04 16:00 0. 731 5 3.00 0.667 0.731 5 1/18/06 16:00 0.686 6 2.00 0.500 0.951 2 10/26/06 0:00 0.653 7 1. 30 0.231 1.36 1 1/09/08 6:00 0.581 8 1.10 0.091 Computed Peaks 1. 23 50.00 0.980 Flow Frequency Analysis Time Series File:7546rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) {ft] Period 0.223 2 2/09/01 20:00 0.882 3.67 1 100.00 0.990 0.056 7 12/28/01 18:00 0.223 3.51 2 25.00 0.960 0.155 4 3/06/03 22:00 0.179 3.19 3 10.00 0.900 0.053 8 8/26/04 7:00 0.155 2.80 4 5.00 0.800 0.102 6 1/05/05 15:00 0.152 2.75 5 3.00 0.667 0.152 5 1/18/06 23:00 0.102 2.19 6 2.00 0.500 0.179 3 11/24/06 8:00 0.056 1. 90 7 1. 30 0.231 0.882 1 1/09/08 10:00 0.053 1. 68 8 1.10 0.091 Computed Peaks 0.662 3. 63 50.00 0.980 Retention/Detention Facility Type of Facility; Side Slope: Pond Bottom Length: Pond Bottom Width: Pond Bottom Area: Top Area at 1 tt. FB: Effective Storage Depth: Stage O Elevation: Storage Volume: Riser Head: Riser Diameter: Number of orifices: Detention Pond 2.00 H:lV 138.50 ft 69.25 ft 9591. sq. ft 13655. 0. 313 3.50 375.50 38887. 0.893 3.50 12.00 2 sq. ft acres ft ft cu. ft ac-ft ft inches Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.22 0. 076 2 2.00 1.90 0 .120 4.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) {cu. ft) (ac-ft) (cfs) (cfs) 0.00 375.50 0. 0.000 0.000 0.00 0.01 375.51 96. 0.002 0.005 0.00 0.03 375.53 288. 0.007 0.006 0.00 0.04 375.54 384. 0.009 0.008 0.00 0.05 375.55 481. 0.011 0.009 0.00 D.06 375.56 577. 0.013 0.010 0.00 0.08 375.58 770. 0.018 0.011 0.00 0.09 375.59 867. 0.020 0.012 0.00 0.10 375.60 963. 0.022 0.013 0.00 0.20 375.70 1935. 0.044 0.018 0.00 0.30 375.80 2915. 0.067 0.022 0.00 0.40 375.90 3903. 0.090 0.026 0.00 0.50 376.00 4900. 0.112 0.029 0.00 0.60 376.10 5905. 0.136 0.031 0.00 0.70 376.20 6919. 0.159 0.034 0.00 0.80 376.30 7942. 0.182 0.036 0.00 0.90 376.40 8973. 0.206 0.038 0.00 1. 00 376.50 10012. 0.230 0.040 0.00 1.10 376.60 11060. 0.254 0.042 0.00 1. 20 376.70 12117. 0.278 0.044 0.00 1. 30 376.80 13182. 0 .303 0.046 0.00 1. 40 376.90 14257. 0. 327 0.048 0.00 1. 50 377.00 15340. 0. 352 0.049 0.00 1. 60 377.10 16431. 0.377 0.051 0.00 1. 70 377.20 17532. 0.402 0.053 0.00 1. 80 377. 30 18641. 0.428 0.054 0.00 1. 90 377.40 19760. 0.454 0.056 0.00 2.00 377.50 20887. 0.479 0.057 0.00 Surf Area (sq. ft) 9591. 9599. 9616. 9624. 9633. 9641. 9658. 9666. 9674. 9758. 9842. 9926. 10011. 10095. 10181. 10266. 10352. 10438. 10525. 10611. 10698. 10786. 10874. 10962. 11050. 11139. 11228. 11317. 2. 02 377.52 21113. 0.485 0.058 0. 00 11335. 2.04 377.54 21340. 0.490 0.061 0.00 11353. 2.06 377.56 21568. 0.495 0.065 0.00 11371. 2.08 377.58 21795. 0.500 0.070 0.00 11389. 2.10 377.60 22023. 0.506 0.077 0.00 11407. 2.12 377.62 22251. 0. 511 0.085 0.00 11425. 2.14 377.64 22480. 0.516 0.094 0.00 11443. 2.16 377.66 22709. 0.521 0.098 0.00 11461. 2.18 377.68 22939. 0.527 0.101 0.00 11479. 2.28 377.78 24091. 0.553 0.113 0.00 11569. 2.38 377.88 25252. 0.580 0.122 0.00 11660. 2.48 377.98 26423. 0.607 0.131 0.00 11750. 2.58 378.08 27602. 0.634 0.139 0.00 11842. 2.68 378.18 28791. 0.661 0.147 0.00 11933. 2.78 378.28 29989. 0.688 0.154 0.00 12025. 2.88 378.38 31196. 0. 716 0.160 0.00 12117. 2.98 378.48 32412. 0.744 0 .167 0.00 12210. 3.08 378.58 33638. 0.772 0.173 0.00 12302. 3.18 378.68 34873. 0.801 0.178 0.00 12396. 3.28 378.78 36117. 0.829 0.184 0.00 12489. 3.38 378.88 37371. 0.858 0,189 0.00 12583. 3.48 378.98 38634. 0.887 0.194 0.00 12677. 3.50 379.00 38887. 0.893 0.195 0.00 12696. 3.60 379.10 40162. 0.922 0.508 0.00 12790. 3.70 379.20 41446. 0.951 1.080 0.00 12885. 3.80 379.30 42739. 0.981 1.810 0.00 12980. 3.90 379.40 44042. 1. 011 2.610 0.00 13075. 4.00 379.50 45354. 1. 041 2.890 0.00 13171. 4.10 379.60 46676. 1,072 3.150 0.00 13267. 4.20 379.70 48007. 1.102 3.390 0.00 13364. 4. 30 379.80 49348. 1.133 3.610 0.00 13460. 4.40 379.90 50699. 1.164 3.820 0.00 13557. 4.50 380.00 52060. 1.195 4.020 0.00 13655. 4.60 380.10 5343 0. 1. 227 4.210 0.00 13752. 4.70 380.20 54810. 1.258 4.390 0.00 13850. 4.80 380.30 56200. 1. 290 4.560 0.00 13949. 4.90 380.40 57600. 1. 322 4. 730 0.00 14047. 5.00 380.50 59010. 1. 355 4.890 0.00 14146. 5.10 380.60 60429. 1. 387 5.050 0.00 14245. 5.20 380.70 61859. 1.420 5.200 0.00 14345. 5.30 380.80 63298. 1.453 5.340 0.00 14445. 5.40 380.90 64748. 1.486 5.490 0.00 14545. 5.50 381. 00 66207. 1. 520 5.630 0.00 14646. Hyd Inflow Outflow Peak Storage Target Cale Stage Elev (Cu-Ft) (Ac-Ft) 1 1. 36 ******* 0.88 3.67 379.17 41001. 0.941 2 0.69 0.23 0.22 3.51 379.01 39000. 0.895 3 0.70 ******* 0.18 3.19 378.69 35018. 0.804 4 0.82 ******* 0.16 2.80 378.30 30242. 0.694 5 0.73 ******* 0.15 2.75 378.25 29665. 0.681 6 0.44 ******* 0.10 2.19 377. 69 23014. o. 528 7 0.58 *****"'* 0.06 1.90 377.40 19784. 0.454 8 0.65 ******* 0.05 1. 68 377.18 17294. 0.397 ~--------------------------------- Route Time Series through Facility Inflow Time Series File:7546dev.tsf Outflow Time Series File:7546rdout Inflow/Outflow Analysis Peak Inflow Discharge: 1.36 Peak Outflow Discharge: 0.882 Peak Reservoir Stage: 3. 67 Peak Reservoir Elev: 379.17 Peak Reservoir Storage: 41001. 0.941 Flow Frequency Analysis Time Series File:7546rdout.tsf Project Location:Sea-Tac CFS at 6: 00 on Jan 9 in Year B CFS at 10:00 on Jan 9 in Year 8 Ft Ft cu-Ft Ac-Ft ---Annual Peak Flow Rates--------Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) (ft) Period 0.223 2 2/09/01 20:00 0.882 3.67 1 100.00 0.990 0.056 7 12/28/01 18:00 0.223 3.51 2 25.00 0.960 0.155 4 3/06/03 22:00 0.179 3.19 3 10.00 0.900 0.053 8 8/26/04 "/: 00 0.155 2.80 4 5.00 0.800 0. J 02 6 1/05/05 15:00 0.152 2.75 5 3.00 0.667 0.152 5 1/18/06 23:00 0.102 2.19 6 2.00 0.500 0.179 3 11/24/06 8:00 0.056 1.90 7 1. 30 0.231 0.882 1 1/09/08 10:00 0.053 1. 68 8 1.10 0.091 Computed Peaks 0.662 3.63 50.00 0.980 Flow Duration from Time Series File:7546rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 33689 54.940 54.940 45.060 0.451E+OO 0.009 5293 8.632 63. 571 36.429 0.364E+OO 0.016 5150 8.399 71. 970 28.030 0.280E+OO 0.022 4744 7.736 79.706 20.294 0.203E+OO 0.028 3744 6.106 85.812 14.188 0.142E+OO 0.034 3305 5.390 91. 202 8.798 0.880E-01 0.041 2033 3. 315 94.517 5.483 0.548E-01 0.047 1402 2.286 96.804 3.196 0.320E-01 0.053 989 1. 613 98.417 1. 583 0.158E-01 0.060 561 0. 915 99.331 0.669 0.669E-02 0.066 64 0.104 99.436 0.564 0.564E-02 0. 072 31 0. 051 99.486 0.514 0. 514E-02 0.078 21 0.034 99.521 0.479 0. 479E-02 0. 085 16 0.026 99.547 0.453 0.453E-02 0. 091 12 0.020 99.566 0.434 0.434E-02 0.097 26 0.042 99.609 0.391 0.391E-02 0 .103 31 0.051 99.659 0.341 0.341E-02 0 .110 21 0.034 99.693 0.307 0.307E-02 0.116 16 0.026 99.720 0.280 0.280E-02 0.122 13 0. 021 99.741 0.259 0.259E-02 0.128 23 0.038 99.778 0.222 0.222E-02 0.135 23 0.038 99.816 0.184 0.184E-02 0.141 20 o. 033 99.848 0.152 0.152E-02 0.147 16 0.026 99.874 0.126 0.126E-02 0.154 16 0.026 99.901 0.099 0.995E-03 0.160 12 0. 020 99.920 0. 080 0.799E-03 0.166 12 0. 020 99.940 0.060 0.603E-03 0 .172 11 0.018 99.958 0. 042 0.424E-03 0.179 10 0.016 99.974 O. 026 0.261E-03 0.185 5 0.008 99.982 0.018 0.179E-03 0.191 6 0.010 99.992 0.008 0.815E-04 0.197 4 0.007 99.998 0. 002 0.163E-04 0.204 0 0.000 99.998 0.002 0.163E-04 0.210 0 0.000 99.998 0. 002 0.163E-04 0.216 0 0.000 99. 998 0. 002 0 .163E-04 0.222 0 0.000 99.998 0.002 0.163E-04 Flow Duration from Time Series File:7546pre.tsf Cutoff Count Frequency GDF Exceedence_Probability CFS % % % 0.059 60766 99.097 99.097 0.903 0.903E-02 0.067 123 0.201 99.297 0.703 0.703E-02 0.075 70 0.114 99.411 0.589 0.589E-02 0.083 48 0.078 99.490 0.510 0.510E-02 0.091 48 0.078 99.568 0.432 0.432E-02 0.100 41 0.067 99.635 0.365 0.365E-02 0.108 36 0.059 99.693 0.307 0.307E·02 0.116 25 0.041 99.734 0.266 0.266E-02 0.124 27 0.044 99.778 0.222 0.222E-02 0.132 26 0.042 99.821 0.179 0.179E-02 0.140 20 0.033 99.853 0.147 0.147E-02 0.148 16 0.026 99.879 0.121 0.121E·02 0.156 15 0.024 99.904 0.096 0.962E-03 0.164 10 0.016 99.920 0.080 0.799E-03 0.172 12 0.020 99.940 0.060 0.603E-03 0.181 12 0.020 99.959 0.041 0.408E-03 0.189 7 0.011 99.971 0.029 0.294E-03 0.197 5 0.008 99.979 0.021 0.212E-03 0.205 4 0.007 99.985 0.0,5 0.147E·03 0.213 3 0.005 99.990 0.010 0.978E-04 0.221 2 0.003 99.993 0.007 0.652E·04 0.229 3 0.005 99.998 0.002 0.163E·04 0.237 1 0.002 100.000 0.000 O.OOOE+OO 0.245 0 0.000 100.000 0.000 O.OOOE+OO 0.253 0 0.000 100.000 0.000 O.OOOE+OO 0.262 0 0.000 100.000 0.000 O.OOOE+OO 0.270 0 0.000 100.000 0.000 O.OOOE+OO 0.278 0 0.000 100.000 0.000 O.OOOE+OO 0.286 0 0.000 100.000 0.000 O.OOOE+OO 0.294 0 0.000 100.000 0.000 O.OOOE+OO 0.302 0 0.000 100.000 0.000 O.OOOE+OO 0.310 0 0.000 100.000 0.000 O.OOOE+OO 0.318 0 0.000 100.000 0.000 O.OOOE+OO 0.326 0 0.000 100.000 0.000 O.OOOE+OO 0.334 0 0.000 100.000 0.000 O.OOOE+OO 0.343 0 0.000 100.000 0.000 O.OOOE+OO Flow Duration from Time Series File:7546rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 33689 54.940 54.940 45.060 0.451E+OO 0.009 5293 8.632 63.571 36.429 0.364E+OO 0.016 5150 8.399 71.970 28.030 0.280E+OO 0.022 4744 7.736 79.706 20.294 0.203E+OO 0.028 3744 6.106 85.812 14.188 0.142E+OO 0.034 3305 5.390 91.202 8.798 0.880E"01 0.041 2033 3.315 94.517 5.483 0.548E-01 0.047 1402 2.286 96.804 3.196 0.320E-01 0.053 989 1.613 98.417 1.583 0.158E-01 0.060 561 0.915 99.331 0.669 0.669E-02 0.066 64 0.104 99.436 0.564 0.564E-02 0.072 31 0.051 99.486 0.514 0.514E-02 0.078 21 0.034 99.521 0.479 0.479E-02 0.085 16 0.026 99.547 0.453 0.453E-02 0.091 12 0.020 99.566 0.434 0.434E·02 0.097 26 0.042 99.609 0.391 0.391 E-02 0.103 31 0.051 99.659 0.341 0.341 E-02 0.110 21 0.034 99.693 0.307 0.307E-02 0.116 16 0.026 99.720 0.280 0.280E-02 0.122 13 0.021 99.741 0.259 0.259E·02 0.128 23 0.038 99.778 0.222 0.222E-02 0.135 23 0.038 99.816 0.184 0.184E-02 0.141 20 0.033 99.848 0.152 0.152E-02 0.147 16 0.026 99.874 0.126 0.126E-02 0.154 16 0.026 99.901 0.099 0.995E·03 0.160 12 0.020 99.920 0.080 0.799E-03 0.166 12 0.020 99.940 0.060 0.603E-03 0.172 11 0.018 99.958 0.042 0.424E-03 0.179 10 0.016 99.974 0.026 0.261 E-03 0.185 5 0.008 99.982 0.018 0.179E-03 0.191 6 0.010 99.992 0.008 0.815E-04 0.197 4 0.007 99.998 0.002 0.163E-04 0.204 0 0.000 99.998 0.002 0.163E-04 0.210 0 0.000 99.998 0.002 0.163E-04 0.216 0 0.000 99.998 0.002 0.163E-04 0.222 0 0.000 99.998 0.002 0.163E-04 Duration Comparison Anaylsis Base File: 7546pre.tsf New File: 7546rdout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time--------------Check of Tolerance------- Cutoff Base New %Change Probability 0.060 0.88E-02 0.67E-02 -24.1 I 0.88E-02 0.073 0.62E-02 0.51E-02 -18.8 I 0.62E-02 0.086 0.48E-02 0.45E-02 -6.8 I 0.48E-02 0.099 0.37E-02 0.37E-02 2.2 I 0.37E-02 0 .113 0.2BE-02 0.29E-02 2.9 I 0.28E-02 0.126 0.21E-02 0.24E-02 12.4 I 0. 21E-02 0 .139 0.15E-02 0.16E-02 6.6 I 0.15E-02 0.152 O.lOE-02 0.lOE-02 -1. 6 I O.lOE-02 0.166 0.78E-03 0.62E-03 -20.8 I 0.78E-03 0.179 0.42E-03 0, 24E-03 -42.3 I 0. 42E-03 0.192 0.24E-03 0.65E-04 -73.3 I 0.24E-03 0.206 O.lSE-03 0.16E-04 -88.9 I 0.15E-03 0.219 0.65E-04 0.16E-04 -75.0 I 0.65E-04 Maximum positive excursion= 0.006 cfs I 5. 0%) occurring at 0 .124 cfs on the Base Data:7546pre.tsf and at 0 .130 cfs on the New Data:7546rdout.tsf Maximum negative excursion~ 0.012 cfs (-15.4%) occurring at 0.075 cfs on the Base Data:7546pre.tsf and at 0.064 cfs on the New Data:7546rdout.tsf Base New %Change 0.060 0.057 -5.1 0.073 0.062 -14.7 0.086 0.078 -9.6 0.099 0.101 1. 5 0.113 0 .116 2.6 0.126 0.131 3. 8 0.139 0.142 2.1 0. l.52 0.152 -0.1 0.166 0.161 -3.1 0.179 0.172 -3.7 0.192 0.180 -·6. 5 0.206 0.188 -8.7 0.219 0.193 -11. 6 PRELIMINARY POND STAGE STORAGE WORKSHEET PROJECT NAME: Ribera-Balko Short Plat PROJ#: 7546 4/15/2003 PAT LOCATION: CLIENT: RE: POND 1 DEPTH STAGE Ff 382.0 1.0 381.0 1.0 380.0 1.0 379.0 1.0 378.0 0.5 377.5 0.5 377.0 1.0 376.0 1.0 375.0 1.0 374.0 0.5 373.5 4/15/2003 Renton, WA Ribera-Balko Enterprises CELLI CELL2 BOTH Ff2 Ff2 Ff2 14,952 14,952 13,831 13,831 12,748 12,748 11,704 11,704 10,698 10,698 3,211 6,425 9,636 2,843 5,787 8,630 2,171 4,595 6,766 1,575 3,490 5,065 1,057 2,472 3,529 826 1,996 2,822 ,NCREMENTAI VOLUMEFT3 14,392 13,290 12,226 11,201 5,084 4,567 7,698 5,916 4,297 471 POND SUMMARY STATIC W.S. EL.= WATER QUALITY VOLUME MAX.WATER SURFACE EL. DETENTION VOLUME= Page I of I 377.50 22,948 CF 381.0 41,800 CF DATE: BY: TOTAL SURFACE VOLUMEFf3 ID 79,139 TOP 64,748 MWSL 51,458 39,232 28,031 22,948 STATIC 18,381 10,683 4,768 471 ~ .. . 7546-storm.xls Size the wet pond: V, = [(0.9)(A;l + (0.25)(A,)] (0.039) = [(0.9)(2.57) + (0.25)(0.71)] (43,560)(0.039) = 4;231 cf (3)(4,231) = 12,693 cf 7546.018.doc [JPJ/ath] 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 5,0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The conveyance system will be designed in accordance with the KCWSWDM and shall be routed as shown on the engineering design plans. Sine the site is less than 10 acres, the rational method was used for the calculations with a 25-year precipitation of 3.45 inches, an initial time of concentration of 6.3 minutes, and a Manning's "N" value of 0.014. 7546.018.doc [JPJ/alh] J08 NAM:: RIBERNBAL.KO JOB#: 7546 FILE NO.: 7546-25.XLS A-Contribl.l1lng Meo (Ac) C= Rllioff Coofflclent 7! is BARG HAUSEN CONSUJING ENGINEERS -PIPE FLOW CALCUlATOR using ttie Rattana I Mt'rthOd Ile Monr'l•l"IQ Fom'!UCI KING COUMY DESIGN FQf,l 25 Yf.AA STO?M NOTE: ENTER DEFAULTS AND STORM DATA IJ:FOT<E BEGINNING- DEFAULTS I c-0.91 r.... 0.014 d-cc 12 Te= 6.3 Qd= Deslcn Flow (cis) COEFFCIENTS FOR HE RATl9"1Al METHOD "1r"-EQUATI0N Qf. Full Copodty ROW' Ccfs) STO,M A, " TC= Time of COncenfrotlon (mll'\) I.a Intensity at Tc ('t"l{f'I) Vda Velocity Of Deslon Flow (fps) Vt-Vebclfy at FtJI fk,w (fps) 2YR IOYR 1158 0.58 2.44 0.6' PREClP= J..<st a,., tlame19r ot Pipe (lri) L,,, Lengtt, of~ (fl) D,. Weter Depth at Qd (h) FROM TO --"'="'= CBI cs, cs, CB3 CB3 CB< CB4 POND :s.. 9ope of pipe(%) ,.,,. Monnll'Q Rouct1r1ass Coefficlerit Ttm lravel Time ot Yd {min) .. ·r ... , =="= "=-' ""="= ~--= === ---- 0.76 2.40 lfil 12 6.3 0.014 0.85 0.57 1.07 lfil 12 6.7 Q.01,4 0.85 0.70 1.09 lf::O 15 72 0.01,4 0.85 0.9.!I. ID.JO 32 15 7.7 O.D14 0.-9 25VR 2.66 0.65 A,-2.6&1 50VR 2.76 0.65 ... 0.651 IOOYR 2.61 06' SUMA ..:i.:.:~ .::.. _::_ !".". ~:--'----~-_::_ _:_ 0.76 OA", 0.6.5 2-77 1 i9 5.12 0.350 0.400 4.90 6.53 5 96 O 42 1.33 OAS 1.13 2.66 3.01 S.42 0.&79 0.725 8.70 4.36 4.91 0.51 2.()3 0.60 L73 2.54 4.38 6.26 0.699 0.616 9.24 5.11 5.52 0.45 2.97 a.as 2 57 2.4<1 6.27 19.24 o.32o o.393 5.89 1s.69 14.~ o.04 Pace l z <( _J n.. ~ <( z <( a: 0 ::.'.?! a: ~ 0 z <( 0 z 0 <( a: 0 co '"'"' [ j ; i r J '' i I ! ! ! i • i7 .. r - .l V1d .lllOHB O)l"lVB-VIBBII N't"ld 30'vNl'fl:Kl rt:IO!S ClNV ~ 1sz 1-zo-vn1 • --- -:-i=~~lfll8/~ NOJ.Nllll ~ .rn .U.I::> ~ ----- 91'SL ·oN sor ·3·o·s \ ,. \ ' ' -- ' "\ \ ' \ '\: I ® --... _ -'""' Ml NOISVOII "'::::::°~ I ... .. --""'Q:".=.:=---"""' ·~-·~- 6.0 SPECIAL REPORTS AND STUDIES 6.0 SPECIAL REPORTS AND STUDIES Included in the special reports and studies is the Wetland Delineation Report describing the on-site wetland and its impacts to the site. Please reference this report for more detailed information. 7546.018.doc (JP/lath] December 28, 1998 Mr. Tim O'Kane NW Retaff Partners, LTD · 600 University St., Suite 3012 Seattle, WA 98100 SEATT:.E RICHLANC FAIRBo\NKS ANCHORAGE Si\lNT LOLIJS BOSTON RE: PRELIMINARY WETLAND DELINEATION, RIBERA PROPERTY, RENTON, WASHINGTON Dear Mr. O'Kane: Shannon & Wilson, Inc. performed the preliminary wetland delineation as described in our contract dated October 22, 1998. The objectives of this project are: I. Complete a wetland delineation and stream classification for the site; 2. Prepare a sensitive area report describing any wetlands and streams found on site, and discussing the City ofRenton's regulations regarding development near wetlands and streams. The enclosed report describes the results of our study. If you have any questions, please call me at (206) 695-6738. Sincerely, SHANNON & WILSON, INC. Katie L. Walter Senior Wetland Scientist ACD:KLW/arz Enclosure: Preliminary Wetland Delineation, Ribera Property, Renton, Washington TIUB--02.hr.doc/pec/am 400 MORTH 34TH STREET· SUITE 100 P. 0. BOX 300303 SEATTLE. WASHINGTON 98103 206•632·8020 FAX 206·633·6777 TDD: 1·800·833·6388 T-1858-02 SI-WJNON & WILSON, INC. EXECUTIVEStThfl\fARY Shannon & Wilson, Inc., conducted a preliminary wetland delineation on property owned by Diane Ribera within the City of Renton boundaries, in King County, Washington (NEI/4 of Section 15, Township 23 N, and Range 5 East). The property is approximately 9.2 acres in size, and located in the southeast quadrant ofNortheast 4th Street and Union Ave. NE, Renton -(Highlands), Washington. Two wetlands were identified and delineated on the Ribera property using the Corps of Engineers Wetland Delineation Manual (1987). Both were associated with Maplewood Creek, which flows along the western and southern boundary of the property. Both wetlands were flagged and surveyed. Based on the City ofRenton's Wetland Management code, both wetlands would be considered Category ill wetlands. The City of Renton requires a 25-foot buffer from the wetland edge if this site is developed. A review of existing sensitive area maps by King County, the City of Renton, and the U.S. Geological Survey (U.S. Dept. oflnterior, Fish & Wildlife) National Wetland Inventory did not indicate any wetlands on the site. However, Maplewood Creek was identified by all of the sources of information. A 25-foot buffer is required on Maplewood Creek. Because the creek is contained within the wetland area, the wetland buffer of25 feet would extend beyond the creek buffer and govern the extent of development on the site. Tl 8S 8--02.rpt.doc/pec/am T-1858-02 SHANNON &WILSON. INC. TABLE OF CONTENTS Page EXECUTIVE SUMMARY .......................................................................................................... i 1.0 IN1RODUCTION .............................................................................................................. 1 1.1 Scope of Services ........................................................................................................ ] . 1.2 Site Location and Description ..................................................................................... 1 · 2.0 METHODS ......................................................................................................................... 2 3.0 DOCUMENTREVIEW ....................................................................................................... 3 4.0 WETLAND AREAS AND STREAM ................................................................................... 3 4.1 Wetland A ................................................................................................................... 4 4.2 Wetland B ................................................................................................................... 4 4 .3 Wetland Buffer ........................................................................................................... 5 4.4 Stream ......................................................................................................................... 5 5.0 WETLAND AND STREAM REGULATIONS .................................................................... 6 5 .1 Wetland Rating ........................................................................................................... 6 6.0 CLOSURE ........................................................................................................................... 6 7.0 REFERENCES ............................................................................................................... 8 LIST OF FIGURES Figure No. 1 Vicinity Map 2 Wetland Inventory Maps 3 Soils Map 4 Wetland Delineation Map Tl8l8-02.J]>Ldoc/pec/am T-1858-02 ii TABLE OF CONTENTS (cont.) SHANNON &WILSON, INC. LIST OF APPENDICES APPENDIX A WETLAND DELINEATION MEIBODOLOGY APPENDIX B WETLAND FIELD DATA SHEETS APPENDIX C IMPORTANT INFORMATION ABOUT YOUR WE1LAND DELINEATION/MITIGATION AND/OR STREAM CLASSIFICATION REPORT Tl1!~8-02.rpldo<lpec/am T-1858-02 JU SHANNON &WILSON. INC. PRELIMINARY WETLAND DELINEATION RIBERA PROPERTY RENTON, WASHINGTON 1.0 INTRODUCTION Shannon & Wilson, Inc. conducted a preliminary wetland delineation on a 9.2 acre site, owned by Diane Ribera, within the City ofRenton boundaries, in King County, Washington (NEI/4 Section 15, Township 23 N, Range 5 East). The fieldwork was conducted on November 20, 1998. This work was performed to provide a preliminary wetland delineation as requested by Tim O'Kane ofNW Retail Partners, LID. 1.1 Scope of Services The scope of services for this project was limited to two main tasks. The first task was to complete a wetland delineation and stream assessment for the site. The second was to prepare a sensitive area report describing any wetlands and streams found on site. Wetlands and streams were identified and classified based on the 1987 Corps ofEngineers Wetland Delineation Manual, and the City ofRenton's Wetlands Management Code. This report includes a review of available information pertaining to the site such as the City of Renton wetland maps and Wetland Management Code, King County Soil Survey, and the National Wetland Inventory Maps. This report also includes a summary of the City ofRenton's regulations regarding development near wetlands and streams. The location of existing wetlands and streams are presented on a surveyed site map. 1.2 Site Location and Description The subject property is located on Northeast 4th Street, at its intersection with Union Avenue NE, in Renton, Washington (Figure 1). The site is approximately 9.2 acres in size. Maplewood Creek flows south along the west border of the site, and exits the site through the middle of the southern border. The site is bounded by Northeast 4th Street on the north, and mixed use properties on the east, west, and south. Property south of the site has been filled creating an approximately 15-foot rise along the south property line. Generally, site topography slopes down gently toward the southwest side of the property. Historically, portions of the property may have been cleared and filled. Currently there are two occupied rental houses along the north TlflSS-02.!pl.doc/pec/am T-1858-02 I SHANNON &WILSON. INC. side of the property. The eastern half of the property is densely forested, and in the western half there are a few willow and spirea patches along the creek, but the predominant vegetation is Scots broom, blackberry, and reed canarygrass. 2.0 MEIBODS ·The two components of a wetland investigation, review of existing information and evaluation of field conditions, were both utilized to make a wetland determination. Both aspects of the investigation are necessary to account for seasonal and historical changes to the land, but a wetland determination can only be made with the support of data from a field reconnaissance. Background information pertaining to the wetland site was collected and reviewed for its usefulness. These information sources included: • U.S. Fish and Wildlife Service National Wetland Inventory Map ofRenton, Washington Quadrangle, 1:24,000 scale (U.S. Department of the Interior, 1988); • U.S. Geological Survey Map of Renton, Washington Quadrangle, 1:24,000 scale (U.S. Geological Survey, 1994); • U.S. Soil Conservation Service (SCS) Soil Survey ofKing County Area, Washington - Sheet No. 11 (U.S. Department of Agriculture, 1979); • King County Sensitive Areas Map Folio -Sheet No. 9 ( King County Environmental Division, 1990); • City of Renton Building Regulations, Chapter 32, Wetlands Management Code (Publishing, Inc., 1998). Katie Walter and Amy Dearborn conducted the preliminary wetland delineation on November 20, 1998. The wetland was delineated using methods described in the 1987 Army Corps of Engineers Wetland Delineation Manual (U.S. Army Corps ofEngineers, 1987), and supplemented by the DOE 1997 Wetland Delineation Manual (Washington State Department of Ecology, 1997). The site was walked to determine if normal conditions exist and to identify plant community types and wetland classification types present. Wetland presence was determined by conducting a Routine Method Delineation. Data points were selected with consideration to plant community types and wetland classification features. Data was collected at each point on vegetation, soils, and hydrology. Corresponding T185R-02.rpt.doo/pcc'am T,1858-02 2 SHANNON&WILSON. INC. ) upland and wetland plots were recorded to more accurately determine the boundaries of on-site wetlands. The triple parameter approach was used, which acknowledges the presence of vegetation, soil conditions, and hydrologic conditions. Under this methodology, vegetation, soils, and hydrology are each evaluated to determine the presence or absence of wetlands. Based on the use of this ·method, an area is considered to be a wetland if each of the following are met: (1) dominant hydrophytic vegetation is present in the area; (2) the soils in the area are hydric; and (3) the necessary hydrologic conditions within the area are met. (Appendix A) 3.0 DOCUMENT REVIEW Neither the U.S. Fish and Wildlife Service National Wetland Inventory Map (Renton, Washington) nor the City of Renton Wetland Inventory Map indicate the presence of any wetlands on or near the site (Figure 2). Maplewood Creek appears on both maps, and is classified as Riverine, intermittent, streambed, seasonally flooded (R.4SBC) on the National Wetlands Inventory Map. The King County Soil Survey (Soil Conservation Service, 1979) (Figure 3) maps the site as containing Alderwood gravelly sandy loam, AgC, with 6-15 percent slopes. This series is considered moderately well drained, with a weak to strongly consolidated substratum within approximately 24 to 40 inches below the surface. Runoff is slow to medium, and the erosion hazard is moderate. This soil type is considered non-hydric on the Washington State list of hydric soils. However, as much as three percent of the areas mapped as Alderwood gravelly sandy loam, 6-15 percent have inclusions of the poorly drained Norma, Bellingham, Seattle, Tukwila, and Shalean soils. These soil inclusions are all considered hydric soil. 4.0 WETLAND AREAS AND STREAM Two wetlands were identified on the property from the field reconnaissance conducted (Figure 4). Both are associated with Maplewood Creek, which flows along the western and southern boundary of the property. Wetland boundaries were primarily established based on the vegetation and topographic changes as well as the presence of standing water and hydric soil indicators. While data were recorded from five data plots: two upland plots and three wetland plots, several other soil pits and sites were examined to established the wetland boundary. Data TJ858-02,ptdoc/pedam T-1858-02 3 SHANNON ~WILSON. INC. ) sheets are included in Appendix B. Based on USFWS Classification of Wetlands in Deepwater Habitats of the United States (1992) both wetlands are palustrine, scrub-shrub (PSS) wetland communities. 4.1 Wetland A Wetland Ais located along the western property boundary and is associated with Maplewood Creek. The wetland is vegetated with a thin scrub-shrub stratum over a thick herbaceous grass understory. _ Reed canarygrass (Phalaris arundinaceae) and bent grass (Agrostis spp.) dominate the herbaceous stratum. There are patches of hard hack (Spirea douglasii), red osier dogwood (Comus stolonifera), willow (Salix spp.), and red alder (A/nus rubra) found in the scrub/shrub stratum. The shrubs are more heavily concentrated immediately adjacent to the stream. The plant indicator status (Appendix A, Table A-1) for plant species found within this wetland ranged· from F AC to F ACW, which meets the criteria for hydrophytic vegetation. Soils were analyzed for color, texture, and moisture content. In general, the soils observed in and adjacent to Wetland A were sandy loam, gravelly sandy loam, and very gravelly sandy loam, with pockets oflarge gravel or fill. Wetland plots contained low-chroma soils. Soil color was very dark gray (IOYR 3/1) 0-6 inches and black (lOYR 2/1) 6-16 inches in data plot l, and dark grayish brown 0-8+ inches (IOYR 4/2) in data plot 4. These are indicators ofhydric soils. The soils were saturated within 12 inches of the surface or inundated with as much as six inches to a foot of water in level areas. The creek was overflowing its banks during our site visit, and appeared to overflow routinely. Thus, wetland hydrology criteria was assumed to persist for a sufficient duration to satisfy the hydrologic criteria. Wetland boundaries were primarily established based on the topographic and vegetative change as well as on presence of standing water and hydric soil indicators. Much of this wetland has been disturbed in the past as . evidenced by ditching of creek, old fill piles, and wetland plant communities indicative of disturbed conditions, such as canarygrass and blackberry. 4.2 Wetland B The wetland is thickly vegetated, with a dense scrub-shrub understory. Aspen (Populus tremuloides), willow (Salix spp. }, snowberry (Symphoricorpus albus), and Pacific Ninebark (Physocarpus capitatus) dominate the scrub/shrub stratum. The herbaceous stratum is composed of slough sedge (CareJ: obnupta). The disturbed wetland edge is dominated by himalayan blackberry (Rubus discolor). The wetland/upland edge along the undisturbed portion of the Tl8S8-02.q,t.do<lpe<lam T-1858-02 4 SHANNON &WILSON, INC. ) wetland had a very distinct vegetative transition, going from the wetland plants described above to a dense cover of salal (Gaultherra shallon) and Oregon grape (Berberis nervosa). The plant indicator status for plant species found within this wetland ranged from FACU to OBL, but the predominate vegetative community was OBL to FACW. The dominant plants in wetland B meet the criteria for hydrophytic vegetation. Soils were analyzed for color, texture, and moisture content The soils observed within the wetland were gravelly sandy loam, with pockets oflarge gravel or fill and organics. Wetland plots contained low-chroma soils. Soil color was very dark gray (2. SY 3/1) 0-9 inches, and dark brown (IOYR 3/3) 9+ inches in data plot 5. These are indications ofhydric soil. These soils were saturated. The western and southern edge of this wetland had been bermed mostly cutting off the hydrologic connection to the stream. The berm also acted to impound water in the wetland. Based on these field conditions, the wetland hydrology criteria was assumed to persist for sufficient duration to satisfy the hydrologic criteria. 4.3 Wetland Buffer The vegetation of the adjacent upland buffer is comprised ofHimalayan blackbeny (Rubus discolor), reed canarygrass (?halaris arundinacea), Scot's broom (Cytisus scoparlus), Canada thistle (Cirsium arvense), and common tansy (Tanacetum vulgare) as well as many varieties of pasture grass. The soils were comprised of gravelly sandy loam and very gravelly sandy loam, and were not saturated. There was some evidence of past human disturbance to the area, such as tire tracks and garbage. 4.4 Stream Maplewood creek flows in a southerly direction through the west side of the property. The west side of the creek bank slopes up very steeply, but the east side has a very gradual slope, which was flooded at the time of our site visit. The creek enters the north side of the property through a culvert under Northeast 4"' Street and roughly flows parallel to the western border of the property. It then flows easterly approximately along the southern border of the property, and leaves the property to the south halfway along the southern property border. The channel was ditched along most of the onsite reach at some time in the past. Maplewood Creek is a tributary to the Cedar River. Our study did not involve an investigation offish use of the stream. However, a review of existing information indicates the stream is ephemeral, going dry during the summer. Also, the creek is reported to have fish migration Tl8.58.lJ2.rpt.doc/p,c/am T-1858-02 5 SHANNON &WILSON. INC. barriers downstream of the project area. This tributary enters the Cedar River after passing through Maplewood Golf & Country Club, and passing under State Route 169. Thus, anadromous salmonids are not likely to be present in this section of the stream. 5.0 WETLAND AND STREAM REGULATIONS · A comprehensive rating system for wetlands is contained in the City of Renton Wetland Management section of the Building Regulation Code. For each wetland rating given by the City of Renton, there is a buffer setback required. The buffer should surround the delineated wetland, and should not be impacted by development unless mitigation for impacts are provided. 5.1 Wetland Rating Wetland A was classified as a Cat~ry 3 wetland.for the following reasons. The wetland is greater than 5000 square feet and, in the past, has been disturbed through ditching, filling, and clearing of vegetation. Wetland B was classified as a Category 3 wetland because it is less than 5000 square feet and it does not meet any of the criteria listed in Category l or 2 wetlands. Category 3 wetlands, as listed in the Renton Wetlands Management regulations, require 25-foot buffers. Steams are regulated within the City of Renton Building Regulations and require 25 foot buffers from the edge of ordinary high water. Ordinary high water in this stream would likely be considered the edge of the ditched bank. Land clearing or tree cutting is not permitted by the City ofRenton within these buffers. Because the stream is contained within the wetland, the wetland buffer would extend beyond the stream buffer and govern the extent of development on the site. 6.0 CLOSURE The findings and conclusions documented in this report have been prepared for specific application to this project, and have been developed in a manner consistent with that level of care and skill normally exercised by members of the environmental science profession currently practicing under similar conditions in the area, and in accordance with the terms and conditions set forth in our agreement. The conclusion and recommendations presented in this report are professional opinions based on interpretation of infonnation currently available to us, and are Tl 858--02.rptooc/peolam T-1858-02 6 SHANNON &WILSON, INC. made within the operational scope, budget, and schedule constraints of this project. No warranty, express or implied, is made. Wetland boundaries identified by Shannon & Wilson are considered to be preliminary until the Corps and/or the local jurisdictional agency validate the flagged wetland boundaries. Validation of the wetland boundary by the regulating agency(s) provides a certification, usually written, that · the wetland boundaries verified are the boundaries that will be regulated by the agency(s) until a specified data or until the regulations are modified. Only the regulating agency(s) can provide this certification. Since wetlands are dynamic communities affected by both natural and human activities, changes in wetland boundaries may be expected; therefore, wetland delineations cannot remain valid for an indefinite period of time. The U.S. Army Corps of Engineers typically recognizes the validity of wedand delineations for a period of five years after completion and the City of Renton for only two years. Development activities on a site two years after the completion of this wetland delineation report may require revision of the wetland delineation. In addition, changes in government code, regulations, or laws may occur. Because of such changes beyond our control, our observations and conclusions regarding this site may need to be revised wholly or in part. SHANNON & WILSON, INC. Katie L. Walter, P.W.S. Senior Wetland Biologist AmyC.Dborn Environmental Scientist T-1858-02 7 SHANNON &WILSON. INC. 7.0 REFERENCES City ofRenton, 1998, City of Renton building regulations: Code Publishing, Inc., Seattle, Wash. Cowardin, L.M., and others, 1979, Classifications of wetlands and deepwater habitats of the United States: U.S. Fish and Wildlife Service Publication FWS/OSB-79/31. King County Environmental Division, Parks, Planning and Resources Department, 1990, King County wetlands inventory: Volume 2 East. U.S. Army Corps of Engineers, 1987, Corps ofEngineers wetlands delineation manual: Vicksburg, Miss., U.S. Army Engineer Waterways Experiment Station, Technical Report Y-87-1. U. S. Department of Agriculture, Soil Conservation Service, 1979, Soil survey ofKing County, Washington. U.S. Department of the Interior, Fish and Wildlife Service, 1988, National wetland inventory map: Renton, Washington, Quadrangle. --~ 1993, National list of plant species that occur in wetlands: Northwest (Region 9), Biological Report 88 (26.9). U.S. Geological Survey, 1994, USGS topographical map: Renton, Washington, Quadrangle. Washington State Department ofEcology, 1997, Washington State wetlands identification and delineation manual: Publication #96-94, Washington State Department of Ecology, Olympia, Wash. Tl8S8--0l.rpt.doolp«lam T-1858-02 8 0 114 1/2 Scale In Miles NOTE Reproduced with permission granted by THOMAS BROS. MAPS e. This map Is copyrighted by THOMAS BROS. MAPS8. 11 is unlawful to copy or reproduce aff or any part thereof, whether for personal use or resale, without permission. All rights reserved. 1 Ribera Property Rento11, Washington VICINITY MAP November 1998 SHANNON & WILSON, INC. Gtoltclw'llcal 111d Envlmml•nlal C11111ultl:nl1 N T-1858-02 FIG. 1 0 1/2 1 Fl E-3 I I Scale in Miles NOTE Map based on 1 :24 000 maps, by City of Renton Wetland Inventory dated 1991, and National Wetlands Inventory, United States Depa_r1ment of lhe Interior dated 1988. Ribera Property Renton, Washington WETLAND INVENTORY MAPS November 1998 SHANNON & WILSON, INC. Geot•cflnlcal all ErwirOMitfl1al Conlllftantl T-1858-02 FIG. 2 ~\.~IN AgD '\S; : ....... . >'-J.·~~;"'":·.:·.:.·~ ~~:'·.-·:: I • '''" .. .. . : r: . . . • 0 112 1 b-----3 E--3 I J Scale in Miles NOTE Map based on a soil survey 1 :24 000 map, part of a set published In 1972 by the United States Department of Agrtculture, Soil Conservation Service and the Washlngtlon Agrtcultural ExperimenfStation. · Ribera Property Renton, Washington SOILS MAP November 1998 T-1858-02 SHANNON & WllSON, INC. FIG 3 G1ol1c.llnh:•I 1r.d £nwlrOM11fltal Con1ulian11 • SHANNON &WILSON. INC. APPENDIX A WETLAND DELINEATION METHODOLOGY T-1858-02 SHANNON &WILSON. INC. APPENDIX A WETLAND DELINEATION METHODOWGY TABLE OF CONTENTS Page A. l WEILAND VEGETATION ....................................................................................... A-1 A.2 HYDRIC SOILS ......................................................................................................... A-2 A.3 WE1LAND HYDROLOGY ....................................................................................... A-2 A.4 REFERENCES ........................................................................................................... A-4 LIST OF TABLES Table No. A-I Definitions Of Plant Indicator Status ................................................................ A-5 A-2 Hydric Soil Indicators ...................................................................................... A-6 A-3 Hydrologic Regimes And Wetland Characteristics ........................................... A-7 Tl 853-() 1,ptAppAdoclpeo'am T-1853-01 A-i SHANNON &WILSON. INC. APPENDIX A WETLAND DELINEATION METHODOLOGY The triple-parameter approach of the Corps of Engineers Wetland Delineation Manual (Corps of Engineers, 1987) was used to delineate the wetlands on site described in this report. Under this methodology, vegetation, soils, and hydrology are each evaluated to determine the presence or absence of wetlands. Based on this methodology, an area is considered to be a wetland if each of the following are met: (1) dominant hydrophytic vegetation is present in the area; (2) the soils in the area are hydric; and (3) the necessary hydrologic conditions within the area are met . . A determination of wetland presence was made by conducting an on-site routine method delineation. Both upland and wetland plots were recorded to more accurately determine the boundaries of on-site wetlands. Wetland boundaries were determined by conducting a walk- through inspection of the property. A.I WETLAND VEGETATION Hydrophytic plants are plant species specially adapted for saturated and/or anaerobic conditions. These species can be found where environmental conditions have a significant duration and frequency of inundation, which produces permanently or periodically, saturated soils. Hydrophytic species, due to morphological, physiological, and reproductive adaptations, have the ability to grow, effectively compete, reproduce, and thrive in anaerobic soil. The U.S. Army Corps of Engineers (Corps) and the U.S. Fish and Wildlife Service (USFWS) has assigned an indicator status to many plant species, which is based on the estimated probability of the species existing under wetland conditions. Plants are categorized as Obligate (OBL), Facultative Wetland (FACW), Facultative (FAC), Facultative Upland (FACU), and Upland (UPL). Species with an indicator status ofOBL, FACW, or FAC are considered to be adaptive to saturated and/or anaerobic (i.e., wetland) conditions and are referred to as hydrophytic vegetation (Table A-1). The approximate percentage of cover for each of the different plant species occurring within the tree, shrub, and herb strata were determined within a plant community .. Dominant plant species are considered to be those having the greatest relative basal area (woody overstory), greatest height (woody understory), and greatest percentage of areal cover (herbaceous understory). Tl853-0l,pt.AppAdodpeclam T-1853-01 A-I SHANNON &WILSON. INC. The indicator status of the dominant plant species within each of the vegetative strata is used to detennine the presence ofhydrophytic vegetation near each data point. A data point was considered to have hydrophytic vegetation of greater than 50 percent of the dominant plant species within the area had an indicator status ofOBL, FACW or FAC. A.2 HYDRIC SOILS Hydric soils are defined as those that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions that favor the growth and regeneration of hydrophytic vegetation. As a result of anaerobic conditions, hydric soils exhibit characteristics directly observable in the field, including high organic matter content, greenish or bluish gray color (gley formation), accumulation of sulfidic material, aquic soil moisture regimes, spots of orange or yellow color (mottling), and dark soil colors (low chromas) (Table A-2). Throughout a large portion of the area delineated as wetland, identification ofhydric soils was aided through observation of surface hydrologic characteristics and indicators of wetland hydrology (i.e., inundation and saturation). The extent ofhydric soils was defined through direct soil observation within several data points, placed both inside and outside the wetland. Soil observations were completed within soil holes dug with a shovel to a depth ofat least 18 inches below the existing ground surface. Soil organic and mineral content was estimated visually and texturally. Soil colors were determined through analysis of the hue, value and chroma best represented in the Munsell Soil Color Chart (Gretag McBeth, 1994). A soil chroma of2 in combination with soil mottling, or a soil chroma of 1 without mottling, typically indicates a hydric soil if within 10 inches of the surface, or directly below the A horizon. A.3 WETLAND HYDROLOGY Hydrologic conditions identifying wetland characteristics occur. during periods when the soils are inundated permanently or periodically, or when the soil is continuously saturated to the surface for sufficient duration to develop hydric soils an.d support vegetation typically adapted for life in periodically anaerobic soil conditions. Wetland hydrology criteria were considered to be satisfied if it appeared that the soil was seasonally inundated or saturated to the surface for a consecutive number of days greater than or equal to 12.5 percent of the growing season (Table A-3). The growing season begins when the soil reaches a temperature of 41 degrees Fahrenheit in the zone of root penetration. The growing season in low elevations in western Washington is typically considered to be from March 1 to October 31 {244 days) (Washington State Department of Ecology, 1997). Tl8Sl.Ol.rpt.AppAdoolpedam T-1853-01 A-2 SHANNON &WILSON. INC. The hydrology was evaluated by direct visual observation of surface inundation or soil saturation in test plots. According to the 1987 Manual, "for soil saturation to impact vegetation, it must occur within a major portion of the root zone (usually within 12 inches of the surface) of the prevalent vegetation." Therefore, if saturated soils or indicators were observed within 12 inches of the surface, positive indicators of wetland hydrology were noted. The area near each data point was examined for additional indicators of wetland hydrology. These indicators include watennarks, scour areas, drift lines, sediment deposits, and drainage patterns. Areas where positive indicators of hydrology were noted were assumed to contain wetland hydrology. T18l3-0 I .,pl App A.doc/pee/nm T-1853-01 A-3 SHANNON &WILSON. INC. A.4 REFERENCES Gretag McB.eth, rev. ed., 1994, ~nsell soil color charts: New Windsor, NY 12553. U.S. Army Corps of Engineers, 1987, Corps ofEngineers wetland delineation manual: Bicksburge, Miss., U.S. Army Waterways Experiment Station, Tech. Report Y-87-1. U.S. Department oflnterior, Fish and Wildlife Services, 1993, National list of plant species that occur in wetlands: Northwest (Region 9), Biological Report 88 (26.9) (Revised 1993) 1989. Washington State Department of Ecology, 1997, Washington State wetlands identification and delineation manual: Washington State Department ofEcology, Publication #96-9994, Olympia, Wash. TIS!i3.0l.rpt.AppAdoclpec/arn T-1853-01 A-4 ) SHANNON &WILSON. INC. TABLEA-1 DEFINITIONS OF PLANT INDICATOR STATUS Plant Indicator Status Categories • Obligate Wetland Plants (OBL) -Plants that occur in wetlands, under natural conditions, approximately 99% of the time. • Facultative Wetland Plants (FACW) -Plants that occur in wetlands approximately 67 -99% of the time. • Facultative (FAC)-Plants that are as likely to be found in wetlands as in non-wetlands; approximately 34-66% of the time in either. • · Facultative Upland Plants (FACU) -Plants that occur in non-wetlands approximately 1-33% of the time. • Obligate Upland Plants (UPL) -Plants that occur in non-wetlands, under natural conditions, approximately 99% of the time. No Indicator (NI)-Species which have not been given an indicator status, and assumed to be upland. Source: National List Of Plant Species That Occur In Wetlands: Northwest (Region 9). U.S. Fish and Wildlife Service Biological Report 88(26.9). (Revised 1993) 89p. Tl853--0l.,pt.AppA.doclpcdam T-1853-01 A-5 . , ) HYDRIC INDICATOR • Organic Content • Sulfidic Material • Soil Color • Water Saturation TABLEA-2 HYDRIC SOIL INDICATORS DIAGNOSTIC CRITERIA SHAl'JNON &WILSON, INC . >50% by volume ( constitutes organic soil) "Rotten egg" odor Matrix Chroma of 2 or less in mottled soils Matrix Chroma of 1 or less in unmottled soils Gleyed colors Soil saturated at 0.5, 1.0, or 1.5 feet from the surface (depending on the soil drainage class and permeability) for a significant period during the growing season. • Soil Color Definitions Hue: Indicates the dominant spectral color (i.e., red, yellow, green, blue, and purple). Value: Measure of degree of darkness or lightness of the color. Chroma: Measure of the purity or strength of the color. Source: Environmental Laboratory, 1987, Co1ps ofEngineers Wetlands Delineation Manual Technical ReportY-87-1, U.S. Anny Waterways EXPeriment Station, Vicksburg, Mississippi. TIS53-0I.rptAppA.dodpec/am T-1853-01 A-6 SHANNON &WlLSON, INC. TABLEA-3 HYDROLOGIC REGIMES AND WETLAND CHARACTERISTICS Permanently inundated (open water)** 100 present Semipermanently to nearly permanently inundated ;, 75 • < 100 present or saturated ** • Regularly inundated or saturated ~25-<75 usually present Seasonally inundated or satnrated ~ 12.5 • < 25 often present Irregularly inundated or saturated ~ S • < 12.5 often absent lntermittently or never inundated or saturated <5 absent Notes:. • Percent of growing season •• Inundation > 6.6 feet mean water depth *** Inundation,: 6.6 feet mean water depth T-1853-01 A-7 SHANNON &WILSON, INC. APPENDIXB WETLAND FIELD DATA SHEETS T-1858-02 Data Point: J_ of 6 DATA FORM ROUTINE WETLAND DETERMINATION )====================r===d,"!o!a!a'"·~~A-91).,t.P, Project/Site: . e .~ l O'l;::;ztl;& Applicant/Owner:--~--------- Invcsti•ator:. I\(;(} /V)vW Job#; 'T·ll:>Sb ·02--. Dale: ll\ Z{;> City: · ~kl!'•~ CoUIJty: ' t,,j'f State·: I.OA-I Have vegetation, soils, or hydrology been disturbed: Yes . ~ Is the area a potential Problem Arca: Yes (!!v (lfnecded, explain on reverse.) VEGETATION !&min!l!ll ~1.nt Su~~i~ Slranlm °t, C2vec !ndi,112t I YI• h./, s 3"."::M1 ,, <!..?st .J::i._ l..t2JLJo ft£.vJ 2. ------3. ------4. ------s. ------6. ------7. ------8. Percent of Dominant Species !hat are OBI., FACW or FAC (except FAC-). •-Dominant species. ' ' .' Cowardin Classification: p"'.,I J~r~__,..,..,..t. .. ".~ p:r~~/11-~s (7! Remarks: ~ {tD fl.,\ HYDROLOGY _ Recorded Data (Descnbe in Remarks): _ Stream, Lake, or Tide Gage . _ Aerial Photograph Olher i._ No Recorded Data Available Field Observations: Depth or surface Water. Depth to Free Water in Pit: Dcplh to Saturated Soil: ------~-(in.) _ . ..,.'-I._ (in.) -~D""'---(in. l . IM.- lls:?wia~m ~J;wi Su~i;ia smn.un •4 C2ver I, ----2. ----3. ----4. ----s. ----6. ---- 7. ---8. I 75n 'li,.., ;? J "~ " • .,. ...... 1-P V ;A.. s·' r:..dr "S pl ,rl· Wetland Hydrology lndicalors · _ lnlJ/ldated ;£_ Saturated in Upper I 2.lnches _ Water Marks _ Water Lines _ Sediment Deposits K Drainage Pancms in Wetlands Oxidized Root Channels in Upper-' 12 Inches _ Water-Stained Leaves _ Local Soil Survey Data Olhcr (E=!ain in Remarks) Remarks: ) -?net d (J)pa, .%,.p tf_" ~µ,_ ·t-ut.e. A}"vA .-1/~Al-~ 1:~ J,f()le Su,f-.e.L \N?.{::.u.. 7v\tc.l.e. <ltc.f;i v7P~wi !ndii:ilQC ----------· -- Data Point of_ SOILS ': .. Map Unit Name: ~ld~!!a.!11"'-GSk: Drain>gc Class: lll!litl iteLA .. Field Observations @ Taxonomy (Subgroup): Confinn Map_l;'ed Type? No Profile Descriorion; Depth Matrix Color Mottle Colors Mottle Texture, Concrclioos, !inmw {Munsell Moist) <Munsen Mois1l Abundance/Contrast Rhlr,ospheres etc, ~ !Dyt,.;fl --~l~ I ---~ \Q ii f.. .:.-/1 -I == ~~ LIRw\.. -- -- -- -- Hydric Soil Indicators: -· -·· Histosol _ Concretions ; - .:.._ High Organic Cont.,;! in Surface Layer _ Histic Epipedon ~ _ Sulfidic Odor _ OrganicStreaking _ · . p Probable Aquic Moisture,Jtegi~e _ Listed on Local Hydric Soils List .. · _ Reducing Con_gi)iQ,n..., _ Listed on Nlllional Hydric Soils List _ Gleyedo~~~:~ _ Other (Explain in Remarks) . Posml't . \) . \ 1M r:}v1 ~,-1---,z._ ',u} lu--J Remarks: -LL S oih > v.._)( I ,t., upp..o,t ' - WETLAND DETERMINATION 11-2-93/DATAFRM/JlUl-llcd/JJw r=. Data Point: 2.. of 5 DATA FORM ROUTINE \VETLAND DETERMINATION. ' 11D i Project/Site: . (l,hci,;,... lei 'k~..u. Date: tt/112 Applicant/Owner: . / ' --City:· ~f.·fu .. Investigator: 11.,-.-.j,1_,, 11 1 Job#· T· lt/ftJ-Di-COWJty: !f:11:1~ Have vegetation;-.:oils, or hydrology been disturbed: Yes !ff> State: lN!::: Is the area a potential Problem Area: Yes o (If needed. explain on reverse.) . VEGETATION Dnmi"""' Pl•"' <nccie< Sm!l!!!l o/t r~~r £ndica12c 012miaan1 flant SJ:i~,i!;l Sm!l!!!l ei1o~ver Jndi~atg[ I. l 1Jh1, .Att: ~}J:;..,-_.>L ~" I. ------ 2. )V\i \•fr\\(, ;)"lttl~/f.'J....." W ...J2j) ~ 2. ------ 3. 'S tzh !ii• J;>\" '1 : .:..o, p iffi) J, ----- 4. 8<Jva'rfo, ~:, _!L. "lPl• 4. ------5. . s. ----------- 6, ------6, ----- 7. ----7, . --------·s. 8, . .. Percent of Dominant Species lhat arc OBI., Id..,;,· FACWor FAC (exceot FAC-l. •-Dominant soecics. . Cowardin Classification: ~ . .. ;04_;~, j f5lu-f Remarks: lvL, R s' HYDROLOGY · _ Recorded Data (Dcscn'be in Remarks): Wetland Hydrology Indicators • _ Su-cam, Lake, or Tide Gago .. · . _ A'erial Photograph -lnundaled. Other · _ Sarun1ed in Upper t 2 Inches _l No Rec.;;;ied Data Available _ Water Mark! . _ Water Lines Field Observ.tions: _ Sediment Deposits _ Drainage Pancms in Wetlands Depth of Swfaco Waicr. (in.) _ Oxidized Root Channels in Upper 12 Inches Depth to Free W$r in Pit: 11fr. (in.) _: Water-Stained Leaves Depth to Saluralod Soil: . (in.) _ Local Soil Swvcy Data • Olher (Exolain in Remarks) '. --,·,..,..,e,d, ... ee... . Rem:irlcs: -A~ V\M I\A.-' p1.f OY I w...., '6U;, ~UVI ,d, '"U/ s ! I SOILS Map Unit Name: A-ltJPA.IJ)Ol!. d Ui..- Taxonomy (Subgroup): Profile Description: Depth Matrix Color Mottle Colors !im;hm IM!!!liell Moii!l {Ml!!litll M2i~l o-5 (p~f? 3/ 2-- <;-1 I\J~(/, !"N\ 1-1'.1 ·'lC:::~t., )IV i -- --,' -- Hydric Soil Indicators: Histosol -_ Histic Epipedon -Sulfidic Odor _ Probable Aquic Moisture.Regime _ Reducing Conditions _ Gleyed or Low-Chroma Colors Remarks: WETLAND DETERMINATION -Hydrophyric V egetarlon Present? ., Hydric Soils Present? Welland H drolo Present? Remarks; ('!£) Yes Yes Data Point of_ . . t ·; •. . Drainage Class: ,MM·{µ'AA ' Field Observations . -.. Confirm Map_eed Type? '· c9 No Mottle Texture, Concretions, 6hlmd'c"'c'e!contt!!S Rhimmh~ '1~ ~~~ ~fu~ ~41;,\~ -l ~-5~4,.'ir>vY>A~ W1-w •, ' .... _.,.,; _ Concrelions ' ,;.,. High ·Organic Cont..;, in Surface Layer _ Organic Streaking _ _ Listed on Local Hydric Soils List _ Listed on National Hydric Soils List _ Other (E,<plain in Remarks) . ' Is this Data Point Within a Weaand? "=============================~..a,.- ; ) \. - , __ '---- ' DATA FORM . . ROUTINE WETLAND DETERJ\UNA. TION. Project/Site: e, kw~ ID k;,, He . I Applicant/Owner: --------=-c-:--:-- lnvcsth1,ator: Ac6 Ii'."" Job#• ,> /b<,£:r C,J-. Ha~ vegetation, soi;s, or hydrology been disturbed: Y cs . ~ ls the area a potential Problem Arca: Y cs (!§:)" · (If needed. elCt>lain on reverse.) Data Point: 3_ of _5 I t6{' ·A-. . Lt.,n Date: 11 /Zp}9ff City:· ,ewi(n,, Colll!ty: /ft n 7 State·: lA..,/a,: . VEGETATION D~iDanI Plant ~t2t,iti ~ ~ Iogjs;;u2r [2ominan1 Plant S12i:~i~ Sir!n!!!l 11/o C2ver Iodi~~IQC I. l~1 . I l. ------ 2, ;/J~'b e\'..'""1&1,;<l· ..t±!)_ ~ 2, ------3. \12::~,,;~ l -S-o '>'II-CW 3. ------4. AAvt>S:i'l .:r5.. (He) 4, ------s. ~<,\' \J (:;J!Jy}.,¥ "3JiI ..1.£. ..:.t!::I<. s . ------ 6. ------6, ------' 7. ------7. -----·s . 8. .. Percent of Dominant Species that arc OBI., '16:t, FACW or FAC /exceot FAC-\. •-Dominant specie, . .. ) : Cowardin Classification: ;;, • Rerna(l,s: (1td.l(A..-.~ . ' HYDROLOGY _ Recorded Data (Descn'bc in Remarks): Wetland Hydrology Indicators _ Stream, Lake, or Tide Gage _ Aerial Photograph ' · _. lnundaled Other .)C-Sa=tcd in Upper 12 Inches :/ No Rcco7dcd Data Available -Water Marks _ Water Linc, . Field Obscrvarions: _ Sediment Deposits _ Drainage Patterns in Wcdands Depth ofSwiacc Waier: t' I(., (in.) _ Oxidized Root Channels in Upper 12 lnchcs Depth to Free Water in Pit -t' ~ (in.) _ Water-Stained Leaves Depth to Saturated Soil: (in.) _ Local Soil Survey Data Other (Explain in Remarks) '. Remarks: ' .. .. ii - SOILS Taxonomy (Subgroup): ______ _ ' ' Profile Description; Depth ~ .... 2 ... :.1 S' ~,$) IS'-r Matrix Color {Munsell Moist) io~i' Jo 'dyz, 4/3 )D~ll-~lz__ . Hydric Soil Jndicalors: _ Hislosol . _ Hisric Epipedon • _ Sullidic Odor Monie Colors <Munsell MoisJ) _ Probable Aquic Moislllrc..Regime _ Reducing Conditions _ Gleyed or Low-Chroma Colors Remarks: ~ [ ? WETLAND DETERMINATION Hyd,aphytic Vegetation Present? Hydric Soils Present? Wetland Hvdrolo Present? Remarks: • at h• L,.-,.,.C,. ........ ~ ,<--.A..~ !!-l-93/0ATA.Fl!MmUl-lkdlJJW Data Point .t : Drainage Class: Field Observations Confurn Mapped Type? · · G) No Motile Abundance/Contrast Textute, Concretions, RhiZOSDberes etc of_ ~~lf'M- C-r6 '= _. Concretions , .. . . _ High Organic Conlent in Surface Layer _ Organic Streaking , _ Listed on Local Hydric Soils List _ Listed on National Hydric Soils List _ Other (Explain in Remarks). ls this Data Point Within a Wedand7 . ' i Data Point: H._ of _2_ DATA FORM ROUTINE WEfLAND DETERMINATION Project/Site: __ ._e.:..•c..::lit::...•-=-J..'-l-J~O~' .... V..,.11.~ ...... t=--------Date: I /-lo -'lg Applicant/Owner: ---------?"""C-c-:-----=--City: ~" 11.:In~v'.:'.:es~t~ig~a~to~r:.:: =1;~!:l:!~~===~J~==~=:::::!:~~=?OC~---1 County: I<, t, II-State: I'\, v:\U Have vegetation, soils, or hydrology been disturbed: Yes Is the area a potential Problem Area: Yes (If needed, explain on reverse.) VEGEI'ATION Dominant Plant S~ies Stim !ii Cover ~ Dominant Plant SRecies Stratum !ii Cover 1. ;,ij,-,,.,;\.-f", 5\.o l~ 1 1k, 1. 2. { f; • f .,,-i ">1e{l~ ,), C&L \'AC, 2. 3. Q\"I'" Cjll,,r" h+-C.-3. 4. 4 .. 5. ' 5. 6. 6. 7. 7. 8. s: Pe=t of Dominant Species Iba! are OBL, ltm1v FACW or FAC {except FAC-). *-Dominant species. Cowardin Classification: 'v-:it~r>f-0 ,......, SC~ J <1.,.,,.J.. Remarks: s· v--µtcw.j 'f'lut' HYDROLOGY _ Recorded Data (Descn"'be in Remarks): _ Stream, I..alce, or Tide Gage _ Aerial Photograph _Other :f:.._ No Recorded Data Available Field Observations: Depth of Surface Water: /. {in.) Depth to Free Water in Pit: ____ (in.) Depth to Saturated Soil: (m.) Wetland Hydrology J'ndicaton 25_ Inundated _ Saturated in Upper 12 Inches _ Water Maries _ Water Lines _ Sediment Deposits _ Drainage Patterns in Wetlands _ Oitidiz.ed R(!OI Channels in Upper 12 Inches _ Water-Stained Leaves IndicatQ[ _ Local Soil Survey Data Other (Explain in Remarks) ,u------------------L--==---'-!-----...;._-------il Remarks: ' ·,, Data Point: of sous Map Unit Name: 4141..1~ ~L,. Dzainago Class: 1&1 ad .),Mt.LL . Field Observations ·GJ Taxonomy (Subgro"!'): Confirm Mapped Type? No Profile Description: Depth Matrix O,lor Mottle Colors Mottle Texture, Concretions, (inches} (Munsell M2il!l. (Munsell Moist) Abundance/Contrast Rhizoml!eres, etg, Q-.fl~ 10::it_~h. ~· -(;: ~' c...?,,,. ,e~J- I . Hydric Soil Indicators: -Histosol -Concretions _ Histic Epipedon _ · High Organic Content in Surface Layer .. _ Sullidic Odor _ Organic Streaking $ Probable Aquic Moisture Regime _ Listed on Local Hydric Soils List -Reducing C',ondilions _ Listed on National Hydric Soils List -Gleyed or Low-Chroma O,lors -Other (Explain in Remarks) Remarks: I~ I ,,\ I ,,,_.. tJo,tL. ---r --, WETLAND DETERMINATION Hydropbytic Vegetation Present? f No ~ Hydric Soils Present? f 'N~ Is this Data Point Within a Wetland? @No Wetland Hydrology Present? No Remarks: ~ ~ ~~ ...... ~ b ,t,J. !· ' .•.. ~ /.,, ~ :~z . ~~~i,~~ l-2-93/DATA.FllMrrRH-11:d/dgw Data Point ..5._ of_ DATA FORM ROUTINE WETLAND DETERMINATION ....... Project/Site: e,kv!--I Q'l£Jl"'-4-D~tc: ltJ::jp b I -. Applicant/Owner. , .. City:· "" ... lnvcstil!.ator. 14-r T'> ./ ~ t.. IV Job#· ,. I h<::t, • "z COUJ!ly: It.~ j ' State: . kllA; H3ve vegetation, s~ils, or hydrology been distw-bcd: Ye~ Is the area a poteitllal Problem Arca: Yes o (if needed. explain on reverse.) VEGETATION • . J22!!Jinant Plant S~~~i~:; r °Isl CQver Indicatot [lQmiaMl flit.DI St2~ci~ S1rnlm! %~QVC[ lndi~~IQC I. (\,;..,..,;y fJtJi,, ,~ti.. ..!iJl C)gL I. -----2.171,.o. ,;,_...,,..,s: W?pbe,.....:r.. -Jo ~i4c,v-2. ------I # .,...... 3. 3. ------------ 4. ------. 4. ------ 5, ------s: .. ------ 6. ------6. ----·--. 7. ------7 • ------·s. 8. -· -. Percent ofDominant Species that are OBI.., Lrro'to FACW or FAC (exceot FAC-\. •-Dominant =eci.:s. l P-,,.J.,;1.,;:;f n ......,_, ''Cowardin Classification: · 1':"1CT.. . ·_, _ ' (/ •. rh Remarks: 1) 1u'/;"-J • 5' &ltu< pi.of (.),PI tA.;_e-.P t,,.P'f' -h ~ . .vl:::__ I ) . HYDROLOGY _ Recorded Da,a (Descnbc in Remarks): Wedand Hydrology Indicators _ Stream, Lake, or Tide Gage . _ Aerial Pholograph · _ Inundllled · Other J'.: Sarura1ed in Upper 12 Inches f__ · No Rec.;;;ied Dafa Available -_ Water Marks Waterlines Field Observations: = Sediment Deposits .:if Drainage Patterns in Wetlands Oxidized Root Channels in Upper Depth of Surface Wafer: -(in.) -. 12 lnchcs Depth lo Free Water in Pit ~ (in) Wa1cr-S1ained Leaves -Depth 10 Saluratcd Soil: {in.) _ Local Soil Survey Data ~ ' Other (Exolain in Remarks) ' . Remarks: H7 a .f l/ . (JIJ>,f''-) '1 f 1,t..t.<: I fi ~ . ()t1,u,._ ;;; ;-..e.;:r. ~- ·1 "Avtlck rk.(.,p ·. SOILS Taxonomy (Subgroup): ______ _ Profile DmrioJion· Depth fin£!!ru Matrix Color {Munsell Moist} Hydric Soil Indicators: _ Histosol _ Histic Epipcdon _ Sulfidic Odor Monie Colors /Munsen MoisO - Y-Probable Aquic Moisture.Jtcgirne _ Reducing Conditions L Gleyed or Low-Chroma Colors WETLAND DETERMINATION . Hydrophytic Vegetation P1escnt? @ Hydric Soils Present? ~ Wetland Hvdrolo..v Present? . No No No Data Point .t : Drainage Class; Field Observations Confinn M"PJ.'ed Type? Mottle Abundance/Contrast Texture, Concretions, RbiWPberes etc. of_ -'l'JM.'!J l.p.y,..,w/~1vt. ,8 fu4j '?'1"' . . -- _ Cpncretions . . ..:.... High Organic Content in Surface Layer _ Organic Streaking ~ . Listed on Local Hydric Soils List :;_ Listed on National Hymie Soils List ; _ Other (Explain in Remarks) . Is this Data Point Wilhin a W Cl land? -· @No .. Remarks: 4ll -f1,t. r.{,<. ~f?us r1t1.P : .. ) ' J ' SHANNON &WILSON, INC. APPENDIXC IMPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION AND/OR STREAM CLASSIFICATION REPORT T-1858-02 I I --111 SHANNON & WILSON, INC. :~ G_eotechnical and Environ(llental Consultants Attachment to Report T-1858-02 Dated, December 28, 1998 Pagolof2 i ) To:~~M'-"'-r~.--"T~im.._~O~'K~a~n~e'--~~~~~~~ NW Retail Partners, LTD Important Information About Your Wetland Delineation/Mitigation and/or Stream Classification Report A WETLAND/STREAM REPORI' IS :BASED ON PROJECT-SPECIFIC FACTORS. Welland delineation/mitigation and stream classification reports are based on a unique set of project-specific factors. These typically include the general nature of the project and property involved, its size, and its configuration; historical use and practice; the location of the project on the site and its orientation; and the level of additional risk the client assumed by virtue of limitations imposed upon the exploratory program. The jurisdiction of any particular wetland/stream is determined by the regulatory authority(s) issuing the permit(s). As a result, one or more agencies will have jurisdiction over a particular wetland or stream with sometimes confusing regulations. It is necessary to involve a consultant who understands which agency(•) has jurisdiction over a particular wetland/stream and what lhe agency(s) pennitting requirements are for that wetlandlsheam. To help reduce or avoid potential costly problems, have the consultant determine how any factors or regulations (which can change subsequent to the report) may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: ./ • • • • If the si71l or configuration of the proposed project is altered. If the location or orientation of the proposed project is modified. If there is a change of ownership . For application to an adjacent site. For construction at an adjacent site or on site. Follc,,ving floods, earthquakes, or other acts of nature. Wetland/stream consultants cannot aecept responsibility for problems that may develop if they are not consulted after factors considered in their reports have changed. Therefore, it is incumbent upon you to notify your consultant of any fucto,s that may.have changed prior to submission of our final report. Wetland boundaries identified aod stream classifications made by Shannoo & Wilson are considered preliminary unb1 validated by the U.S. Army Corps of Enginee,s (Corps) and/or the local jurisdictional agency. Validation by the regulating agency(s) provides a certification, usually written, that the wetland boundaries verified are lhe boundaries that will be regulated by the agency(•) until a specified date, or until the regulations arc modified, and that the stream has been properly classified. Only the regulating agency(•) can provide this certification. MOST WETLAND/STREAM "FINDINGS" ARE PROFESSIONAL ESflMATES. Site exploratioo identifies wetlaod/stream conditions at only those points where samples are taken and when they are talren, but the physical moans of obtaining data preclude the determination of precise conditions. Consequently, the information obtained is intended to be sufficiently accurate for design, but is subject to interpretation. AdditionallJI data derived through sampling and subsequent laboratory testing are c:<lrapolated by the consultant who then rende,s an opinion about overall conditions, the lila,ly reaction to proposed construction activil)I and/or appropriate design. Even under optimal circumstances, actual conditions may differ from those \ought to exist because no consultant, no matter how qualified, and no c:<ploration program, no matter how comprehensive, can reveal <bat is hidden by earth, rock, and time. Nothing can be done to prevent the unanticipated, but steps can he taken to help reduce . kir impacts. For this reason, most experienced owners retain their consultants through the construction or wetland mitigation/stream classification stage to identify variances, to conduct additional evaluations that may be needed, and to recommend solutions to problems encountered on site. Page 2 of 2 WETLAND/STREAM CONDITIONS CAN CHANGE. Since natural systems are dynamic systems affected by both natural processes and human activiti"'I chani:es in wetland boundan,, and stream conditions ll!BY be expected, Therefore, delineated wetland boundaries and stream classifications cannot remain valid fol an :indefinite period of time. The Coips typically recognizes the validity of wetland delineations for a period of five years after completion. Some city and county agencies recogni2" the validity of wetland delineations for a period of mo years. If a period of years have passed since the wetland/stream report was completed, the owner is advised to have the consultant reexamine the wetland/stn:am to determine if the classification is still accurate. ConstIUction operations at or adjacent to the site and natural events such as floods, earthquakes, or water fluctuations may also affect conditions and, thus, tho continuq adequacy of the wetland/stream report. The consultant should be kept apprised of any such events and should be consulted to determine if additional evalualion is necessary. TIIE WETLAND/STREAM REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when plans are developed based on misinterpretation of a wetland/stream report. To help zvoid lhese problems, the consultant should be retained to work with other appropriate professionals to eitplain relevant wetland, stream, geological, and other findings, 'and to reviM !he adequacy of plans and specifications relati"' to these issues. DATA FORMS SHOULD NOT BE SEPARATED FROM THE REPORT. Final dala forms are developed by the consullant based on inteq,relation of field sheets (assembled by site personnel) and laboratory evaluation of field samples. Only final data forms customarily are included in a report. These data forms should not, under any circumstances, be drawn for inclusion in other drawings because drafters may commit errors or omissions in the transfer process. Although photographic reproduction eliminates this problem, it does nothing to reduce the possibility of misinteipreliug the forr- Wben this occurs, delays, disputes, and unanticipated costs are frequently the result. To reduce the likelihood of data form misinterprelation, contractors, enginee,s, and planners should be given ready access to the complete report. Those who do nol provide such access may proceed under the mistaken impression !hat simply d_isclaimiqi responsibility for the accuracy of information always insulates !hem from attendant liabilit)I Providing the best available infurmation to contractors, engineers, and planners helps prevent costly problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Becaus,, a wetland delineation/steam classification is based extensively onjudgmenl and opinion, it is filf less exact than other design discipline& This situation has resulted in wholly unwananted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in written transmittals These are not exculpatory clauses designed to foist the consultant's liabilities onto someone-else; rather, Uiey are definiti"' clauses that identify where the consultant's responn'bilities begin and end. Their use helps all parties involved recogni2" !heir individual responsibilities and talce appropriate action. Some of these definiti"' clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. THERE MAY BE 0111ER STEPS YOU CAN TAKE TO REDUCE RISK. Your consultant will be pleased to discµss other techniques or designs that can be employed to mitigate the risk of delays and to provide a variety of altemati"" that may be beneficial to your project. Contact your consultant for further information, \ '· 4/9S l.. 7.0 OTHER PERMITS 7.0 OTHER PERMITS • Clearing and Grading Permit • Building Pemtit , Utility Pemtit 75%.018.doc [JPJ/ath] 8.0 EROSION AND SEDIMENTATION CONTROL ANALYSIS AND DESIGN 8.0 EROSION AND SEDIMENTATION CONTROL ANALYSIS AND DESIGN The proposed project will include clearing and grading of the existing property to provide the proper base for constructing approved buildings. Erosion control measures, including defining clearing limits, perimeter protection, traffic area stabilization, sediment retention, surface water controls and cover measures, will be utilized to prevent sediment transport from the site. Both temporary and permanent erosion measures will be implemented during and after construction. 7546.018.doc [IPl/ath] 9.0 BOND QUANTITIES, FACILITIES SUMMARIES, AND DECLARATION OF COVENANT 10.0 OPERA TIO NS AND MAINTENANCE MANUAL I i ( KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 -DETENTION PONDS Maintenance Defect component General Trash & Debris Poisonous Vegetation Pollution Unmowed Grass/ Ground cover Rodent Holes Insects Tree Growth Side Slopes of Pond Erosion Storage Area Sediment Pond Dikes Settlements Emergen~ Overflow/ pillway Rock Missing 1998 Surface Water Design Manual Conditions When Maintenance fsNeeded Any trash and debris which exceed 1 cubic foot per 1,090 square feet (this Is about equal to the amount of trash It would take to fill up One standard size office garbage can). In general, there shouid be no visuaJ evidence of dumping. Any poisonous or nuisance vegetation which may constitute a haza!d to County personnel or the pubHc. Oil, gasoline, or other contaminants of one . gallon or more or any amol.Dlt found that could: · 1) cause damage to plant. animal, or marine life; 2) constitute a fire hazard; or 3) be flushed downstream during rain stomns. If facility is located in private residential area. moWing ls needed when grass exceeds 18 inches in height In other SJ'flas, the general policy is to make the pond sjte match adjacent ground cover and terrain as long as there is no interference with the function of the facility. Any evidence of rodent holes n facill~ Is acting as a dam or berm, or any evidence o water piping through dam or berm via rodent holes. When insects such as wasps and hornets interfere with maintenance activities. Tree growth does not allow maintenance access or interferes with maintenance activity fi.e., slope mowing, silt removal, vectoring, or equipment movements). If traes are not Interfering with access, leave trees alone. Eroded damage over 2 Inches deep where cause of damage ls still present or where there Is potential for contlnued erosion. Accumulated sediment that exceeds 10% of the designed pond depth. Any part of dike which has settled 4 inches lower than the design elevation. Only one layer of rock exists above native soil In area five squa,e feet or larger, or any exposure pf ne11ve soll at 1he top of out flow path of spillway. Rip-rap on Inside slopes need not be replaced. A•l Results Expected When Maintenance Is Performed Trash and debris cleared from site. No danger of poisonous vegetation where County personnel or the public might nonnally be. (Coordinallon with Seattle-King County Health Department) No contaminants present other 1han a surface film. (Coordination with Seattle/King County Health Department) When mowing Is needed, grass/ground cover should be mowed to 2 Inches in height Mowing of selected higher use areas rather than the entire stope may be ac6eptabte for some situations. Rodents destroyed and dam or berm repaired. {Coordination with SeattlelKing County Health Department) Insects destroyed or removed from site. Trees do not hinder maintenance acUvtties. Selectively cultivate trees such as alders for firewood. Slopes should be stabilized by using apprOpriate erosion control measure(s); e.g., roek reinforcement. planting ot grass, compaction. Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to oontrol erosion. Dike should be buit back to the design elevation. Replace rocks to design standards. 911198 APPENDIX A MAINTENANCE STANDARDS FOR PRJV A TEL Y MAINTAINED DRAINAGE FACILlTIES NO. 4 -CONTROL STRUCTURE/FLOW RESTRICTOR Malntenan·ce Defect Component General Trash and Debris (Includes Sediment) Structural Damage Cleanout Gate Damaged or Missing Orifice Plate Damaged or Missing Obstructions Overflow Pipe Obstructions Manhole Catch Basin 911/98 Condition When Maintenance is Needed Distance between debris build-up and bottom ol orifice plate is less than 1-1/2 feet Structure is not securely attached to manhole wall and outlet pipe structure shoukl support at least 1,000 lbs of up or down pressure. Structure is not in upright position (allow up to 10% from plumb). Connections to outlet pipe are not watertight and show signs of rust Any holes·-other than designed holes-in the structure. Cleanout gate is not water1ight or is missing. Gate cannot be moved .up and down by one maintenance person. Chain leading to gate Is missing or damaged. Gate Is rusted over 50% of its surface area. Control device is not working properly due to missing, out of place, or bent orifice plate. Any trash, debris, sediment, or vegetation blocking the plate. Any trash or debris blocking (or having the potential of blocking} the overflow pipe. Results Expected When Maintenance fs Performed All trash and debris removed. Structure securely attached to wall and outlet pipe. Structure in correct position. Connections to outlet plpe are water tight; structure repaired or replaced and works as de61gned. Structure has no holes other than designed holes. Gate is watertight and works as designed. Gate moves up and down easily end Is watertight Chain is In place and works as designed. Gate is repaired or replaced to meet design standards .. Plate is in place and works as designed. Pla1e Is kee of all oostructlons and wori<s as designed. Pipe &S free of an obstructions and works as designed. See "Closed Detention Systems" Standards No. 3 See "Closed Detention Systems' Standanls No. 3 See "Catch Basins" Siandards No. 5 See 'Catch Basins" Standards No.5 1998 Surface Water Design Manual A-4 ( APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILmES NO. 5-CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash & Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Tr,i35h or debris (in the basin) that exceeds 1/3 the No trash or debris In the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basfn. Trash or debris ln any inlet or outlet pipe blocking l nlet and ouUet pipes free of more than 1 /3 of Its height trash or debris. Dead anlmals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases (e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition present which volume would attract or support lhe breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/4 Inch past Frame is even with curb. Frame and/or Top Slab curb face Into the street (It applicable). Top .slab has holes larger than 2 square inches or Top slab Is free of holes and cracks wider than 114 inch {Intent Is to make sure cracks. aH material I.a running into bastn). Frame not sitting flush on top slab, I.e., separation Frame is stttlng flush on top of more than 3/4 Inch of the frame from the lop slab. slab. Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through crackst or maintenance. person Judges that struct\.lre is unsound. Cracks wider than 112 inch and longer than 1 foot No cracks more than 1/4 inch at 1he }olnt of any Inlet/ ouGet pipe or any evidence wide at the Joint of lnleVoutlet of soil particles entering catch basin through pipe. cracks. Sedlment/ Basin has settled mora than 1 Inch or has rotated Basin replaced or repaired to Misalignment more than 2 Inches out ot alignment design standards. y '· 1998 s·urface Wa\er Design Manual 9/1198 A-5 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FAC!LmEs NO. 5-CATCH BASINS (COfvTINUEO, Maintenance Defect Conditions When Maintenance is Needed Component Fire Hazard Presence of chemicals such as natural gas, oil and gasoline. Vegetation Vegetation growing across and blocking more lhan 10% of 1he basin opening. Vegetation growing in inleVoutlet pipe Joints that Is more than six inches tall and Jess than six inches apart. Pollution Nonflammable chemica)s of more than 1/2 cubic foot per three feet of basin length. Catch Basin Cover Cover Not tn Place· Cover is missing or only partially in place. Any open catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on maintenance Not Working person with proper lools. Bolts Into frame have less than 112 Inch of thread. Cover Difficult to One maintenance person cannot remove lid after Remove applying 80 lbs. of Ifft; Intent is keep cover from sealing off access to maintenance. Ladder Ladder Rungs [adder is unsafe due to missing rungs, misalignment, Unsafe rust, cracks, or sharp edges. Metal Grates Grate with opening wider than 7/8 inch. (If Applicable) Trash and Debris Trash and debris that is blocking more than 20% of grate surface. Damaged or Grate missing or broken member(s) of the grate. Missing. NO. 6 DEBRIS BARRIERS (E.G., TRASH RACKS) Maintenance Components General Meta 9/1198 Defect Trash and Debris Damaged/ Missing Bars. Condition When Maintenance is Needed Trash or debris that is plugging more than 20'Y,.. of the openings In the barrier. Bars are bent out of shape more than 3 inches. Bars are missing or entire barrier missing. Bars are loose and rust is causing 50% deterioration to any part of barrier. A-6 Results Expected When Maintenance is performed No flammable chemicals presenl No vegetation blocking openlng to basin. No vegetation or root growth present No pollution present other than surface film. Catch basin cover is dosed Mechanism opens with proper tools. Covet can be removed by one maintenance person. Ladder meets design standards and allows maintenance person safe access. Grate opening meets design standards. Grate free of trash and debris. Grate is in place and meets design standards. Results Expected When. Maintenance is Performed. Barrier clear to receive capacity flow. Bars In place 'With no bends more than 314 Inch. Bars in place according to design. Repair or replace barrier to design standards. 1998 Surface Water Design Manual ., ( ( ....... _.,,! APPENDIX A MAIN'IENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILI11ES NO. 8 -FENCING Maintenance Components General Wire Fences Defect Missing or Broken Parts Er05ion Damaged Parts Deteriorated Paint or Protective Coating Openings in Fabric N0.9-GATES Maintenance Component General 911/98 Delec1 Damaged or-Missing Members Op""lngs In Fabric Condltlons When Maintenance is Needed Any defect In the ferx::e that permits easy entry to a facility. Erosion more than 4 inches high and 12·18 inches wide permitting an opening under a fence, · Post out of plumb more 1han 6 fnches. Top ra~s bent more than 6 indies. Any part of fence (Including pos~ top rails, and fabric) more than 1 foot out of design alignment. Missing or loose tension wire. Missing or loose barbed wire that Is sagging more than 2-1 /2 inches between posts. Extension arm mtsslng, broken, or bent out of shape more than 1 1/2 inclles. Part or parts that have a rusting or scaling condition that has affected structuraf adequacy. Openings in fabric are such that an 8-lnch- dlameter ball could fit ttirough. Conditions When Maintenance is Needed Missing gate or IOC!dng devices. Broken or missing hinges such that gate cannot be easily opened and closed by a maintenance person. Gate is oul of plumb more than 6 inches and more than 1 foot out of design alignm""t Mlsslng stretcher bar, stretcher bands, and ties. See 'Fencing' Slandan! No. 8 A-8 Results Expected When Maintenance is Performed Parts in place to provide adequate' security. No opening under the fence that e:xceeds 4 iriches in height. Post plumb to within 1R1/2 inches. Top rail free of bends greater than 1 inch. Fence is aligned and meets design standards. Tension wire in place and holding fabric. Barbed wire In place with less than 314 Imm sag between post. Extension arm in place with no bends larger than 3/4 incll. Slructurally adequate posts or parts with a uniform protective coating. No openings In fabric. Results Expected When Malntenance Is Performed Gates and Locking devices In place. Hinges lntact and lubed. Gate Is working freely. Gate is aligned and vertical. Stretcher bar, bands and ties in place. See "Fencing" Standard No. e I998 Surface Water Design Manual C { .. APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FAC!LlTIES NO. 10 ·CONVEYANCE SYSTEMS (PIPES & DITCHES) Maintenance Component Ptpes Defect Sediment & Debris Vegetation Damaged Conditions When Maintenance Is Needed Accumulated sediment that exceeds 20% of the diameter of the pipe. Vegetation that reduces free movement of water through pipes. Protective ooating ls damaged; rust is causing more than 50'Yo deteriorafion to any part of pipe. Results Expected When Maintenance is Performed Pipe cleaned of all sediment and debris. All vegetation removed so water flows freely through pipes. Pipe repaired or replaced. Any dent that decreases the cross section area of Pipe repaired or replaced. Open Ditches Catch Basins Debris Barriers (e.g., Trash Rack) Trash & Debris Sedfment Vegetation Erosion Damage to Slopes Rock Lining Out of Place or Missing (If Applicable). pipe by more than 20%. Trash and debris exceeds 1 cublc foot per 1,000 square feet ol ditch and slopes. Accumulaled sediment that exceeds 20 % of the design depth. Vegelation that reduces free movement of wator through ditches. See 'Ponds' standard No. 1 Maintenance person can see native soil beneath the rock lining. See •catch Basins: Standard No. 5 See "Debrls Barriers" Standard No.6 NO. 11 -GROUNDS (LANDSCAPING) Maintenance Component General Trees and Shrubs Detect Weeds (Nonpoisonous) Safely Hazard Trash or Litter Damaged 1998 Surface Water Design Manual Conditions When Maintenance ls Needed Weeds growing in more than 20% of the landscaped area (trees and shrubs only). Any presence ol poison Ivy or other poisonous vegetation. Paper, cans, bottles, totaling more than 1 cubic foot within a landscaped area (trees and shrubs only} ol 1,000 square feet. Limbs or parts of trees or shrubs that are split or broken which affect more than 25% ol lhe total foJfage of the tree or shrub. Tre8s or shrubs that have been .blown down or knocked over. Trees or shrubs Which are not adequately supported or are leaning over, causing exposure of the roots. A-9 Trash and debris cleared from ditches. Ditch cleaned/ flushed ol alt sediment and debris so that It matches design. Water flows freely through ditches. See 'Ponds" Standard No. 1 Replace rocks to design standards. See ~catch Basins'! Standard No.5 See "Deblis Barriers· Standard No.6 Results Expected When Maintenance ls Performed Weeds present in less than 5% of lhe landscaped area. No poisonous vegetation present In landscaped area. Area clear of litter. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Tree or shrub in place free of Injury. Tree or shrub in place and adequately supported; remove any dead or diseased trees. 9/1/98 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 12 -ACCESS ROADS/ EASEMENTS Malntehance Defect Condition When Maintenance is Needed Results Expected When Component MaJntehance is Performed General Trash and Debris Trash and debris exceedS 1 cubic foot per 1,000 Roadway tree of debris which square feet Le., trash and debris would fill up could damage tires. one standards size gaJbage can. Blocked Roadway Debris which could damage vehicle tires (glass Roadway tree of debris which or metal). could damage tires. Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to ,ess than 14 feet high. Any obstruction restricting the access to a 1 O to Obstruction removed to allow at ~ 21oot widfll for a dfstance of more than 12 feet least a 12 foot access. or any point restricting access to less than a 1 o foot width. Road Surface Settlement, P,otholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth Mush Spots, Ruts depth and 6 square feet in area. In general, any with no evidence of settlement, surface dafeCI which hinders or prevents potholes, mush spots, or ruts. maintenance access. Vege1atlon In Road Weeds growing 111 the road surface that are Road surface free o1 weeds taller Surface more than 6 Inches tall and less than 6 Inches than 2 Inches. tall and less than 6 Inches -rt wtthln a 400· square foot area. Modular Grid Bund-up of sediment mildly contaminated with Removal ol sediment and d",sposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soila or catch basin sedrments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 6 Shoulder free of erosion and I Ditches inches wide and 6 inches deep. matching the surrounding r~d. \ Wee~s and Brush Weeds and brush exceed 16 inches In height or Weeds and brush cut to 2 Inches hinder maintenance· access:. in height or cleared in such a way as to aUow maintenance access.. 9/1/98 1998 Surface Water Design Manual A-10 APPENDIX A MAINTENANCE ST AND ARDS FOR. PR.IV ATEL Y MAINTAINED DR.AINA GE FACILITIES C.) Weteonds Malntenance Defect Condition When Maintenance Is Needed Results Expected When Component Maintenance is Performed Wetpond Vegetation Vegetation such as grass and weeds need to be Vegetation should be mowed to mowed when it stans to •mpede aesthetics of pond. 4 to 5 Inches in haight. Trees Mowing is generally required when height exceeds and bushes should be removed 18-lnches. Mowed VE!getation should be removed where they are interfering with from areas where it could enter the pond, either pond malnlenance activities. when the pend level rises. or by rainfall runoff. Trash and Debris Accumulation that exceeds 1 CF per 1000-SF of Trash and debris removed from pond area pond. Inlet/ Outlet Pipe Inlet' Outlet pipe clogged with sediment and/ or No clogging or blockage In uie debris material. Inlet and outlet piping. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in Pond exceeds the depth of sediment zone plus 6~1nches, bottom. Bottom usually the first ceU. Oil Sheen on Water Prevalent and v\slble oll sheen. Removal of sediment from pond bottom. Erosion Erosion of the pond's side slope5 and/ or scouring of Slopes should be slabilized by the pond bottom, that exceeds 6-inches, or where using proper erosion control continued erosion is prevalent. measures, and repair methods. Settlement of Pond Any part of U,ese components that has settled 4-Dike/ berm is repaired to Dike/ Berm inches or lower than the design elevatlon, or specifications. inspector determines dike/ berm Is unsound. Rock Window Rock window is clogged with sediment Window is free of sediment and debris. Overflow Spillway Rock is missing and soil Is exposed at top of Replace rocks to specifications. ( spillway or· outside slope. . .. .i ( 9/i/98 1998 Surface Water Design Manual A-12 APPENDIX B Geotechnical Report Associated Earth Sciences, Inc Associated Earth Sciences, Inc. D[J. ~~~ ~ ~ ty__J L!1:..J Serving tlie 1'acific Northwest Since 1981 December 16, 2013 Project No. KE130602A Lozier Development, LLC 1300 114m Avenue SE, Suite 100 Bellevue, Washington 98004 Attention: Mr. Paul G. Ebensteiner Subject: Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Whitman Court Townhomes 351 Whitman Court NE Renton, Washington Dear Mr. Ebensteiner: We are pleased to present these copies of our preliminary report for the referenced project. This report summarizes the results of our subsurface exploration, geologic hazards, and geotechnical engineering studies, and offers preliminary recommendations for the design and development of the proposed project. Our report is preliminary since project plans were under development at the time this report was written. We should be allowed to review the recommendations presented in this report and modify them, if needed, once final project plans have been formulated. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions, or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland Washington Bruce L. Blyton, Senior Principal BLB/pc KE130(i02A2 Projects\20130602\KE\WP Kirkland • Everett • Tacoma 425-827-7701 425-259-0522 253-722-2992 www.aesgeo.com lgeotechnica('Engineering Water 'Resources 'Environmenta( .'Assessments an,{ 'Remedlation Sustainati(e 1Jevefoyment Services lgeofogic .'Assessments Associated Earth Sciences, Inc. Serving tfie 'Pacific Nortfiwest Since 1981 Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report WHITMAN COURT TOWNHOMES Renton, Washington Prepared for Lozier Development, LLC Project No. KE130602A December 16, 2013 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS, AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT WHITMAN COURT TOWNHOMES Renton, Washington Prepared for: Lozier Development, LLC 1300 I 14th Avenue SE, Suite 100 Bellevue, Washington 98004 Prepared by: Associated Earth Sciences, Inc. 911 5"' A venue Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 December 16, 2013 Project No. KE130602A Whitman Court Townhomes Renton, Washington Subsuiface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Project and Site Conditions I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazards, and preliminary geotechnical engineering studies for the proposed Whitman Court Townhomes project. The site location is shown on the "Vicinity Map," Figure 1. The approximate locations of exploration pits completed for this study are shown on the "Site and Exploration Plan," Figure 2. Logs of the subsurface explorations completed for this study are included in the Appendix. 1.1 Purpose and Scope The purpose of this study was to provide geotechnical engineering design recommendations to be utilized in the preliminary design of the project. This study included a review of selected available geologic literature, excavation of six exploration pits, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow ground water. Geotechnical engineering studies were completed to establish recommendations for the type of suitable foundations and floors, allowable foundation soil bearing pressure, anticipated foundation and floor settlement, pavement subgrade recommendations, and drainage considerations. This report summarizes our fieldwork and offers preliminary recommendations based on our present understanding of the project. We recommend that we be allowed to review the recommendations presented in this report and revise them, if needed, when a project design has been finalized. 1. 2 Authorization Our work was completed in general accordance with our scope of work and cost proposal dated November 8, 2013. This report has been prepared for the exclusive use of Lozier Development, LLC, and its agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. 2.0 PROJECT AND SITE DESCRIPTION This report is based on review of a conceptual site plan prepared by GMS Architectural Group. The project, as we understand it, consists of the construction of multifamily residential housing, with associated access and parking, at the existing property located at 351 Whitman December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc-KE!30602A2-Projectsl20I306021KE\lVP Page I Whitman Coun Townlwmes Renton, Washington Subsutface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Pro;ect and Site Conditions Court NE in Renton, Washington. In addition to the proposed housing, a bank building is planned for the northernmost portion of the site. We understand that previous grading activities have occurred at the subject site, including the construction of a storm water pond, and that the existing pond is currently under consideration to provide storm water storage for the currently-proposed project. Also, we understand that infiltration of storm water is currently under consideration for the area of the proposed bank at the north end of the site. The subject site encompasses three parcels (King County Parcel Nos. 5182100020, 5182100021, and 5182100022) totaling roughly 5.13 acres in size. The site fronts the south side of NE 4th Street and the west side of Whitman Court. The topography of the site is generally flat-lying to gently sloping downward to the west and south, and is currently vegetated with grass. A wetland, delineated by others, is located along the western portion of the site. The southern portion of the site extends eastward, up a moderate slope, along the southern boundary of an adjacent post office property. The subject site appears to have been previously developed, with a storm water pond at the southwest portion of the site and utility stub-outs extending onto the site from Whitman Court. 3.0 SUBSURFACE EXPLORATION Our field study included excavating a series of exploration pits to gain subsurface information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Our explorations were approximately located in the field relative to known site features shown on the topographic site plan. The locations of the exploration pits are shown on Figure 2. The conclusions and recommendations presented in this report are based, in part, on the exploration pits completed for this study. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, interpolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -Kl::130fi02A2-Projecu\20130602\KE\WP Page 2 Whitman Court Townhomes Renton, Washington 3 .1 Exploration Pits Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Proiect and Site Conditions Exploration pits were excavated with a track-mounted excavator. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by a representative from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of selected applicable geologic literature. Because of the nature of exploratory work below ground, interpolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. 4.1 Stratigraphy Fill Fill soils (soils not naturally placed) were encountered at the locations of exploration pits EP-1 through EP-4 to depths ranging from 2 to 5 feet below the ground surface. Fill encountered generally consisted of loose to medium dense silty fme to coarse sand with gravel. The encountered fill generally included scattered organics, wood debris and, at exploration pits EP-1 and EP-4, other assorted debris, such as plastic pieces, concrete and rubber. At EP-1 through EP-3, the fill was underlain by a 6-inch-thick buried topsoil layer. The exact extent and depth of fills can vary widely over short distances. Fill is also expected in unexplored areas of the site. Due to their variable depth, density and organic content, we recommend that the existing fill soils be evaluated at the time of foundation excavation to determine the suitability of the existing fill for foundation support. Vashon Recessional Outwash At exploration pits EP-5 and EP-6, and below the fill at EP-1 through EP-4, Vashon recessional outwash sediments were encountered, extending to a depth of 7 .5 feet below the ground surface at EP-6, and beyond the depths explored of 8 to 12 feet below the ground surface at the remaining exploration pits. The outwash sediments were deposited by meltwater streams flowing from the receding Vashon glacier approximately 10,000 years ago. The December 16, 2013 ASSOCIATED EAR711 SCIENCES, INC. JPUpc -KEJ30602A2-Projectsl20130602\KE\WP Page 3 Whitman Coun Townlwmes Renton, Washington Subsuiface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Rep01t Pro;ect and Site Conditions outwash material consisted primarily of a medium dense, moist to wet, fine to coarse sand with gravel, gravel beds, and varying amounts of silt. This unit is generally suitable for support of light to moderately loaded foundations and for pavement subbase when properly compacted as discussed in this report. Vashon Lodgement Till Sediments encountered below the Vashon recessional outwash at EP-6 generally consisted of very dense silty fine to medium sand with gravel. We interpret these sediments to be representative of Vashon lodgement till. The Vashon lodgement till was deposited directly from basal, debris-laden glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. The high relative density of the unweathered till is due to its consolidation by the massive weight of the glacial ice from which it was deposited. The Vashon lodgement till extended below the depth explored. 4.2 Geologic Mapping Review of the regional geologic map titled Geologic Map of King County, compiled by Derek B. Booth et al., dated May 2006, indicates that the area of the subject site is underlain by Vashon lodgement till (Qvt), with Vashon recessional outwasb (Qvr) mapped in the vicinity. Our interpretation of the sediments encountered at the subject site is in general agreement with the regional geologic map. 4.3 Hydrology We encountered ground water seepage in exploration pits EP-1, EP-2 and EP-4 at depths of 10 feet, 11.5 feet and 10 feet, respectively, below the ground surface. We expect ground water seepage across much of the site to be limited to interflow. Interflow occurs when surface water percolates down through the surficial weathered or higher-permeability sediments and becomes perched atop underlying, lower-permeability sediments. It should be noted that the occurrence and level of ground water seepage at the site may vary in response to such factors as changes in season, precipitation, and site use. 4.4 Laboratory Test Results Grain size analysis tests were completed on two samples selected from the explorations. Results are included in the Appendix. December 16, 2013 ASSOCIATED EAKI'H SCIENCES, INC. JPUpc -KEJ306Q2A2 -Projects\20130602\KE\WP Page 4 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic, slope, and ground and surface water conditions, as observed and discussed herein. The discussion will be limited to seismic and erosion issues. 5.0 SEISMIC HAZARDS AND MITIGATIONS Earthquakes occur regularly in the Puget Lowland. The majority of these events are small and are usually not felt by people. However, large earthquakes do occur, as evidenced by the 1949, 7.2-magnitude event; the 2001, 6.8-magnitude event; and the 1965, 6.5-magnitude event. The 1949 earthquake appears to have been the largest in this region during recorded history and was centered in the Olympia area. Evaluation of earthquake return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture, 2) seismically induced landslides, 3) liquefaction, and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 5 .1 Surficial Ground Rupture Based on the reviewed geologic map, the project site is located approximately 3 miles to the south of the Seattle Fault Zone. Recent studies by the U.S. Geological Survey (USGS) (e.g., Johnson et al., 1994, Origin and Evolution of the Seattle Fault and Seattle Basin, Washington, Geology, v. 22, p.71-74; and Johnson et al., 1999, Active Tectonics of the Seattle Fault and Central Puget Sound Washington -Implications for Earthquake Hazards, Geological Society of America Bulletin, July 1999, v. 111, n. 7, p. 1042-1053) have provided evidence of surficial ground rupture along a northern splay of the Seattle Fault. The recognition of this fault is relatively new, and data pertaining to it are limited, with the studies still ongoing. According to the USGS studies, the latest movement of this fault was about l, 100 years ago when about 20 feet of surficial displacement took place. This displacement can presently be seen in the form of raised, wave-cut beach terraces along Alki Point in West Seattle and Restoration Point at the south end of Bainbridge Island. The recurrence interval of movement along this fault system is still unknown. However, due to the distance between the subject site and the Seattle Fault Zone, the potential for surficial ground rupture is considered to be low during the expected life of the structures, and no December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc-KEJ3(){,()2A2-Pro}ects\20130601\KE\WP Page 5 Whitman Court Townhomes Renton, Washington Subswface Expwration. Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations mitigation efforts beyond complying with the current 2012 International Building Code (!BC) are recommended. 5.2 Seismically Induced Landslides It is our opinion that the potential risk of damage to the proposed development by seismically induced slope failures is low due to the lack of steep slopes in the project area. 5 .3 Liquefaction Liquefaction is a process through which unconsolidated soil loses strength as a result of vibrations, such as those which occur during a seismic event. During normal conditions, the weight of the soil is supported by both grain-to-grain contacts and by the fluid pressure within the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the grain-to-grain contact, increase the pore pressure, and result in a temporary decrease in soil shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is supported by pore pressure alone. Liquefaction can result in deformation of the sediment and settlement of overlying structures. Areas most susceptible to liquefaction include those areas underlain by non-cohesive silt and sand with low relative densities, accompanied by a shallow water table. The subsurface conditions encountered at the site pose little risk of liquefaction due to relatively high density and lack of shallow ground water. No detailed liquefaction analysis was completed as part of this study, and none is warranted, in our opinion. 5.4 Ground Motion Structural design of the buildings should follow 2012 IBC standards using Site Class "C" as defined in Table 20.3-1 of American Society of Civil Engineers (ASCE) 7 -Minimum Design Loads for Buildings and Other Structures. 6.0 EROSION HAZARDS AND MITIGATIONS As of October 1, 2008, the Washington State Department of Ecology (Ecology) Construction Storm Water General Permit (also known as the National Pollutant Discharge Elimination System [NPDES] permit) requires weekly Temporary Erosion and Sedimentation Control (TESC) inspections and turbidity monitoring of site runoff for all sites 1 or more acres in size that discharge storm water to surface waters of the state. We provide in the following sections recommendations to address these inspection and reporting requirements, should they be December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KE130602A2-Projec,s\20130602lKEIWP Page 6 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations triggered. The following sections also include recommendations related to general erosion control and mitigation. The TESC inspections and turbidity monitoring of runoff must be completed by a Certified Erosion and Sediment Control Lead (CESCL) for the duration of the construction. The weekly TESC reports do not need to be sent to Ecology, but should be logged into the project Storm Water Pollution Prevention Plan (SWPPP). Ecology requires a monthly summary report of the turbidity monitoring results signed by the NPDES permit holder. If the monitored turbidity equals or exceeds 25 nephelometric turbidity units (NTU) (Ecology benchmark standard), the project best management practices (BMPs) should be modified to decrease the turbidity of storm water leaving the site. Changes and upgrades to the BMPs should be documented in the weekly TESC reports and continued until the weekly turbidity reading is 25 NTU or lower. If the monitored turbidity exceeds 250 NTU, the results must be reported to Ecology via phone within 24 hours and corrective actions should be implemented as soon as possible. Daily turbidity monitoring is continued until the corrective actions lower the turbidity to below 25 NTU, or until the discharge stops. This description of the sampling benchmarks and reporting requirements is a brief summary of the Construction Storm Water General Permit conditions. The general permit is available on the internet1. In order to meet the current Ecology requirements, a properly developed, constructed, and maintained erosion control plan consistent with City of Renton standards and best management erosion control practices will be required for this project. Associated Earth Sciences, Inc. (AESI) is available to assist the project civil engineer in developing site-specific erosion control plans. Based on past experience, it will be necessary to make adjustments and provide additional measures to the TESC plan in order to optimize its effectiveness. Ultimately, the success of the TESC plan depends on a proactive approach to project plarming and contractor implementation and maintenance. The most effective erosion control measure is the maintenance of adequate ground cover. During the local wet season (October 1" through March 31 '\ exposed soil should not remain uncovered for more than 2 days unless it is actively being worked. Ground-cover measures can include erosion control matting, plastic sheeting, straw mulch, crushed rock or recycled concrete, or mature hydroseed. Surface drainage control measures are also essential for collecting and controlling the site runoff. Flow paths across slopes should be kept to less than 50 feet in order to reduce the erosion and sediment transport potential of concentrated flow. Ditch/swale spacing will need to be shortened with increasing slope gradient. Ditches and swales that exceed a gradient of about 7 to 10 percent, depending on their flow length, should have properly constructed check dams installed to reduce the flow velocity of the runoff and reduce the erosion potential within 1 http://www. ecy. wa. gov /programs/wg/ stormwater/construction/constructionfinalpermit. pdf December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ 30602.42 -Projectsl20J 30{J()2\KE\ WP Page 7 Whitman Coun Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Repon Geologic Hazards and Mitigations the ditch. Flow paths that are required to be constructed on gradients between 10 to 15 percent should be placed in a riprap-lined swale with the riprap properly sized for the anticipated flow conditions. Flow paths constructed on slope gradients steeper than 15 percent should be placed in a pipe slope drain. AES! is available to assist the project civil engineer in developing a suitable erosion control plan with proper flow control. Silt fencing should be utilized as buffer protection and not as a flow-control measure. Silt fencing should be placed parallel with topographic contours to prevent sediment-laden runoff from leaving a work area or entering a sensitive area. Silt fences should not be placed to cross contour lines without having separate benn/swale flow control in front of the silt fence. 6 .1 Erosion Hazard Mitigation To mitigate the erosion hazards and potential for off-site sediment transport, we would recommend the following: 1. Construction activity should be scheduled or phased as much as possible to reduce the amount of earthwork activity that is performed during the winter months. 2. The winter performance of a site is dependent on a well-conceived plan for control of site erosion and storm water runoff. The TESC plan should include adequate ground- cover measures, access roads, and staging areas to maintain a workable site. The contractor should implement and maintain the required measures as necessary through all phases of site work. A site maintenance plan should be in place in the event storm water turbidity measurements are greater than the Ecology standards. 3. TESC measures for a given area to be graded or otherwise worked should be installed soon after ground clearing. The recommended sequence of construction within a given area after clearing would be to install sediment traps and/or ponds and establish perimeter flow control prior to starting mass grading. 4. During the wetter months of the year, or when large storm events are predicted during the summer months, each work area should be stabilized so that if showers occur, the work area can receive the rainfall without excessive erosion or sediment transport. The required measures for an area to be "buttoned-up" will depend on the time of year and the duration the area will be left un-worked. During the winter months, areas that are to be left un-worked for more than 2 days should be mulched or covered with plastic. During the summer months, stabilization will usually consist of seal-rolling the subgrade. Such measures will aid in the contractor's ability to get back into a work area after a storm event. The stabilization process also includes establishing temporary December 16, 2013 ASSOCIATED EARTH SCIBNCES. INC. JPUpc -KEI30602A2 -Projects\20130602\KE\ WP Page 8 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Geologic Hazards and Mitigations storm water conveyance channels through work areas to route runoff to the approved treatment facilities. 5. All disturbed areas should be revegetated as soon as possible. If it is outside of the growing season, the disturbed areas should be covered with mulch, as recommended in the erosion control plan. Straw mulch provides a cost-effective cover measure and can be made wind-resistant with the application of a tackifier after it is placed. 6. Surface runoff and discharge should be controlled during and following development. Uncontrolled discharge may promote erosion and sediment transport. Under no circumstances should concentrated discharges be allowed to flow over the top of steep slopes. 7. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of silt fences around pile perimeters. During the period between October 1" and March 31 ", these measures are required. 8. On-site erosion control inspections and turbidity monitoring (if required) should be performed in accordance with Ecology requirements. Weekly and monthly reporting to Ecology should be performed on a regularly scheduled basis. A discussion of temporary erosion control and site runoff monitoring should be part of the weekly construction team meetings. Temporary and permanent erosion control and drainage measures should be adjusted and maintained, as necessary, for the duration of project construction. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate mitigation elements (BMPs) throughout construction, as recommended by the erosion control inspector, the potential adverse impacts from erosion hazards on the project may be mitigated. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ30602A.2 -Proje.ctsl:Z0130602\KE\lVP Page 9 Whitman Court Townhomes Renton, Washington Subsu,jace Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations III. PRELIMINARY DESIGN RECOMMENDATIONS 7.0 INTRODUCTION Our exploration indicates that, from a geotechnical standpoint, the parcel is suitable for the proposed development provided the recommendations contained herein are properly followed. The foundation bearing stratum is relatively shallow, and conventional spread footing foundations may be utilized for the proposed structure. Consequently, foundations bearing on either the medium dense to very dense natural sediments, or on structural fill placed over these sediments, are capable of providing suitable building support. The infiltration of storm water into the soils under! ying the fill encountered below the proposed parking area for the bank at the north end of the site may be feasible based on our preliminary explorations and laboratory testing. The site is underlain by existing fill material which varies in thickness, density, and content. Based on this variability, we recommend that the foundation sub grade soils be evaluated during excavation to determine the suitability of the existing fill for foundation support. If foundation areas determined to be underlain by existing fill that are deemed unsuitable for foundation support, we recommend that the existing fill be removed and replaced, as described in the following sections of this report. 8.0 SITE PREPARATION Existing buried utilities, vegetation, topsoil, and any other deleterious materials should be removed where they are located below planned construction areas. All disturbed soils should be removed to expose underlying, undisturbed, native sediments and replaced with structural fill, as needed. All excavations below final grade made for clearing and grubbing activities should be backfilled, as needed, with structural fill. Erosion and surface water control should be established around the clearing limits to satisfy local requirements. Once clearing and grubbing activities have been completed, existing fill, where encountered, should be addressed. We recommend that existing fill be removed from below areas of planned foundations to expose underlying, undisturbed native sediments, followed by restoration of the planned foundation grade with structural fill. Where deemed necessary removal of existing fill should extend laterally beyond the building footprint by a distance equal to the depth of overexcavation. For example, if existing fill is removed to a depth of 2 feet below a planned footing area, the excavation should also extend laterally 2 feet beyond the building footprint in that area. Care should be taken not to disturb support soils of existing foundations. Support soils should be considered those soils within a prism projected December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPLlpc -KEJ 306()2A2 -Projectsl20J 30(J()2\KE\ WP Page 10 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations downward and outward from existing footings at inclinations of lH: IV (Horizontal:Vertical). Where existing fill must be removed and replaced with structural fill, conventional shallow foundations may be used for building support. The required depth and extent of removal should be determined by an AESI representative in the field based on actual conditions encountered during excavation. 8 .1 Site Drainage and Surface Water Control The site should be graded to prevent water from ponding in construction areas and/or flowing into excavations. Exposed grades should be crowned, sloped, and smooth drum-rolled at the end of each day to facilitate drainage. Accumulated water must be removed from subgrades and work areas immediately prior to performing further work in the area. Equipment access may be limited, and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely sequence. If an effective drainage system is not utilized, project delays and increased costs could be incurred due to the greater quantities of wet and unsuitable fill, or poor access and unstable conditions. We anticipate that perched ground water could be encountered in excavations completed during construction. We do not anticipate the need for extensive dewatering in advance of excavations. The contractor should be prepared to intercept any ground water seepage entering the excavations and route it to a suitable discharge location. Final exterior grades should promote free and positive drainage away from the building at all times. Water must not be allowed to pond or to collect adjacent to foundations or within the immediate building area. We recommend that a gradient of at least 3 percent for a minimum distance of 10 feet from the building perimeters be provided, except in paved locations. In paved locations, a minimum gradient of I percent should be provided, unless provisions are included for collection and disposal of surface water adjacent to the structures. 8.2 Subgrade Protection To the extent that it is possible, existing pavement should be used for construction of staging areas. If building construction will proceed during the winter, we recommend the use of a working surface of sand and gravel, crushed rock, or quarry spalls to protect exposed soils, particularly in areas supporting concentrated equipment traffic. In winter construction staging areas and areas that will be subjected to repeated heavy loads, such as those that occur during construction of masonry walls, a minimum thickness of 12 inches of quarry spalls or 18 inches of pit run sand and gravel is recommended. If sub grade conditions are soft and silty, a geotextile separation fabric, such as Mirafi SOOX or approved equivalent, should be used between the subgrade and the new fill. For building pads where floor slabs and foundation construction will be completed in the winter, a similar working surface should be used, December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ 306(}2A2 -ProjeCls\20130602\KE\ WP Page 11 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations composed of at least 6 inches of pit run sand and gravel or crushed rock. Construction of working surfaces from advancing fill pads could be used to avoid directly exposing the subgrade soils to vehicular traffic. Foundation subgrades may require protection from foot and equipment traffic and ponding of runoff during wet weather conditions. Typically, compacted crushed rock or a lean-mix concrete mat placed over a properly prepared subgrade provides adequate subgrade protection. Foundation concrete should be placed and excavations backfilled as soon as possible to protect the bearing surface. 8.3 Proof-Rolling and Subgrade Compaction Following the recommended clearing, site stripping, and planned excavation, the stripped subgrade within the building areas should be proof-rolled with heavy, rubber-tired construction equipment, such as a fully loaded, tandem-axle dump truck. Proof-rolling should be performed prior to structural fill placement or foundation excavation. The proof-roll should be monitored by the geotechnical engineer so that any soft or yielding subgrade soils can be identified. Any soft/loose, yielding soils should be removed to a stable subgrade. The subgrade should then be scarified, adjusted in moisture content, and recompacted to the required density. Proof-rolling should only be attempted if soil moisture contents are at or near optimum moisture content. Proof-rolling of wet subgrades could result in further degradation. Low areas and excavations may then be raised to the planned finished grade with compacted structural fill. Subgrade preparation and selection, placement, and compaction of structural fill should be performed under engineering-controlled conditions in accordance with the project specifications. 8.4 Overexcavation/Stabilization Construction during extended wet weather periods could create the need to overexcavate exposed soils if they become disturbed and cannot be recompacted due to elevated moisture content and/or weather conditions. Even during dry weather periods, soft/wet soils, which may need to be overexcavated, may be encountered in some portions of the site. If overexcavation is necessary, it should be confirmed through continuous observation and testing by AESI. Soils that have become unstable may require remedial measures in the form of one or more of the following: 1. Drying and recompaction. Selective drying may be accomplished by scarifying or windrowing surficial material during extended periods of dry and warm weather. 2. Removal of affected soils to expose a suitable bearing subgrade and replacement with compacted structural fill. December 16, 2013 ASSOCIATED EARlli SCIENCES, INC. JPUpc -KE130602A2 -Projectsl20130602lKElWP Page 12 Whitman Court Townhomes Renton, Washington Subsu,face Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations 3. Mechanical stabilization with a coarse crushed aggregate compacted into the subgrade, possibly in conjunction with a geotextile. 4. Soil/cement admixture stabilization. 8.5 Wet Weather Conditions If construction proceeds during an extended wet weather construction period and the moisture-sensitive site soils become wet, they will become unstable. Therefore, the budget for site grading operations should consider the time of year that construction will proceed. It is expected that in wet conditions additional soils may need to be removed and/or other stabilization methods used, such as a coarse crushed rock working mat to develop a stable condition if silty subgrade soils are disturbed in the presence of excess moisture. The severity of construction disturbance will be dependent, in part, on the precautions that are taken by the contractor to protect the moisture-and disturbance-sensitive site soils. If overexcavation is necessary, it should be confirmed through continuous observation and testing by a representative of our firm. 8.6 Temporary and Permanent Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, we anticipate that temporary, unsupported cut slopes in the existing fill or recessional outwash can be made at a maximum slope of 1.5H: 1 V or flatter. Temporary slopes in lodgement till deposits may be planned at lH: 1 V. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. If ground water seepage is encountered in cut slopes, or if surface water is not routed away from temporary cut slope faces, flatter slopes will be required. In addition, WISHA/OSHA regulations should be followed at all times. Permanent cut and structural fill slopes that are not intended to be exposed to surface water should be designed at inclinations of 2H: 1 V or flatter. All permanent cut or fill slopes should be compacted to at least 95 percent of the modified Proctor maximum dry density, as determined by American Society for Testing and Materials (ASTM):D 1557, and the slopes should be protected from erosion by sheet plastic until vegetation cover can be established during favorable weather. 8.7 Frozen Subgrades If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw and then be recompacted prior to placing subsequent lifts of structural fill or foundation components. Alternatively, the frozen material could be stripped from the subgrade to reveal unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL!pc -KEJ30602A2 -Projecrs\20130602\KE\WP Page 13 Whitman Court Townhomes Renton, Washington 9.0 STRUCTURAL FILL Suhsurjace Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations All references to structural fill in this report refer to subgrade preparation, fill type and placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer, the upper 12 inches of exposed ground in areas to receive fill should be recompacted to 90 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. If the subgrade contains silty soils and too much moisture, adequate recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current City of Renton codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the locations of the roadway edges before sloping down at an angle of2H:1V. The contractor should note that any proposed fill soils must be evaluated by AESI prior to their use in fills. This would require that we have a sample of the material 72 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions. The native and existing fill soils present on-site contained variable amounts of silt and are considered moisture-sensitive. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction with at least 25 percent retained on the No. 4 sieve. December I 6, 2013 ASSOCIATED EARTH SCIENCES, INC. JPLlpc -KE130602A2 -Projects\201306021KE\WP Page 14 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Georechnical Engineering Report Preliminary Design Recommendations A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses, and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid in developing a suitable monitoring and testing program. 10.0 FOUNDATIONS For footings bearing directly on the medium dense to very dense natural sediments, or on structural fill placed over these materials, as described above, we recommend that an allowable foundation soil bearing pressure of 2,500 pounds per square foot (psf) be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection. However, all footings must penetrate to the prescribed bearing stratum, and no footing should be founded in or above organic or loose soils. All footings should have a minimum width of 18 inches. It should be noted that the area bound by lines extending downward at lH: 1 V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM:D 1557. In addition, a 1.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded as described above should be on the order of % inch or less. However, disturbed or otherwise unsuitable soil not removed from footing excavations prior to footing placement could result in increased settlements. All footing areas should be inspected by AES! prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the "Drainage Considerations" section of this report. 10.1 Drainage Considerations Foundations should be provided with foundation drains placed at the base of footing elevation. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPL/pc -KEJ 3060242 -Projects\20J306(J2\KE\ WP Page 15 Whitman Court Townhomes Renton, Washington Subswface Exploration, Geologic Hawrds, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations washed pea gravel. The drains should be constructed with sufficient gradient to allow gravity discharge away from the proposed building. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the proposed structure to achieve surface drainage. 11.0 FLOOR SUPPORT Floor slabs can be supported on suitable native sediments, or on structural fill placed above suitable native sediments. Floor slabs should be cast atop a minimum of 4 inches of clean, washed, crushed rock (such as 5/,-inch "chip") or pea gravel to act as a capillary break. Areas of subgrade that are disturbed (loosened) during construction should be compacted to a non-yielding condition prior to placement of capillary break material. Floor slabs should also be protected from dampness by an impervious moisture barrier at least 10 mils thick. The moisture barrier should be placed between the capillary break material and the concrete slab. 12.0 FOUNDATION WALLS All backfill behind foundation walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed using an equivalent fluid equal to 35 pounds per cubic foot (pcf). Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. Walls with sloping backfill up to a maximum gradient of2H:1V should be designed using an equivalent fluid of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. As required by the 2012 IBC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall backfill materials, we recommend a seismic surcharge pressure of 5H and lOH psf, where H is the wall height in feet for the "active" and "at-rest" loading conditions, respectively. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the mid-point of the walls. The lateral pressures presented above are based on the conditions of a uniform backfill consisting of excavated on-site soils, or imported structural fill compacted to 90 percent of ASTM:D 1557. A higher degree of compaction is not recommended, as this will increase the pressure acting on the walls. A lower compaction may result in settlement of the slab-on-grade December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ 30602A.2 -Projects\20130602\KEI WP Page 16 Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations or other structures supported above the walls. Thus, the compaction level is critical and must be tested by our firm during placement. Surcharges from adjacent footings or heavy construction equipment must be added to the above values. Perimeter footing drains should be provided for all retaining walls, as discussed under the "Drainage Considerations" section of this report. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum, 1-foot-wide blanket drain to within 1 foot of finish grade for the full wall height using imported, washed gravel against the walls. A prefabricated drainage mat is not a suitable substitute for the gravel blanket drain unless all backfill against the wall is free-draining. 12.1 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural glacial soils or supporting structural fill soils, and by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following allowable design parameters: • Passive equivalent fluid = 350 pcf • Coefficient of friction = 0.30 13.0 DRAINAGE CONSIDERATIONS All retaining and perimeter foundation walls should be provided with a drain at the base of the footing elevation. Drains should consist of rigid, perforated, PVC pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set at or slightly below the bottom of the footing grade beam, and the drains should be constructed with sufficient gradient to allow gravity discharge away from the buildings. In addition, all retaining walls should be lined with a minimum, 12-inch-thick, washed gravel blanket that extends to within 1 foot of the surface and is continuous with the foundation drain. Roof and surface runoff should not discharge into the foundation drain system, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the structures to achieve surface drainage. December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ30602A2 -Projectsl20130602\KE\WP Page 17 Whitman Court Townhomes Renton, Washington Subswjace Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations 14.0 PRELIMINARY INFILTRATION EVALUATION Much of the subject site is underlain by fill material that is not a suitable infiltration receptor. However, the grain-size analysis test results for samples collected below the fill at the proposed bank parking area at the north end of the site indicate fines contents ranging from roughly 8 to 9 percent of the fraction passing the No. 10 sieve. The classification of the samples tested most closely fits the texture class "sand" referenced in Table 3.7 in the 2005 Washington State Department of Ecology Stormwater Management Manual for Western Washington (Ecology Manual). For preliminary planning purposes only, this material has an uncorrected short-term infiltration rate of 8 inches per hour, with an Estimated Design (long-term) Infiltration Rate of 2 inches per hour. Should a design infiltration rate be needed for site-specific design, we recommend that AESI perform infiltration testing using a large-diameter infiltrometer, generally corresponding to the procedure described as a pilot infiltration test (PIT) in the Ecology Manual, at the proposed infiltration location(s) prior to final design in order to provide site-specific rates of infiltration. The PIT test(s) should take place at the bottom elevation of the proposed infiltration system. AESI is also available to conduct cation exchange capacity or organic content testing of site soils for in situ treatment of storm water, if requested. The suitability for the infiltration of storm water can be limited by the presence of a seasonal high water table. For seasonal high water table monitoring, we recommend that AESI install a pressure transducer connected to an automatic data logger in a well point which would be installed to Jess than 10 feet in depth. After the well point has been completed, we will develop the well and record the initial depth to ground water. The data logger would record hourly water levels, and would be installed and left in place for up to approximately 1 year to capture ground water levels during the coming winter and the following summer. Bimonthly hand measurements of the water level in the well would be collected in conjunction with downloading of water level data recorded by the data logger. The data would be downloaded, entered into a spreadsheet, compensated for barometric pressure effects, and calibrated with the manual water level measurements. 15.0 PAVEMENT SUBGRADE RECOMMENDATIONS Site preparation for areas to be paved should consist of excavating to remove the topsoil and the loose portion of the upper soils, exposing the underlying stable sediments. Since the density of the upper soils is variable, random loose areas may exist, and the depth and extent of stripping can best be determined in the field by the geotechnical engineer. In addition, the subgrade should be slightly crowned to drain toward the edges of the paved area. After the area to be paved is excavated, the exposed ground should be recompacted to at least 95 percent December 16, 2013 ASSOCIATED EARTH SCIENCES, INC. JPUpc -KEJ 30602A2 -Projects\20130602\KE\ WP Page 18 • Whitman Court Townhomes Renton, Washington Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Preliminary Design Recommendations of ASTM:D 1557, If required, structural fill may then be placed to achieve desired sub base grades. The appropriate pavement section may then be placed over the prepared subgrade. 16.0 PROJECT DESIGN AND CONSTRUCTION MONITORING Our report is preliminary since project plans were not finalized at the time this report was written. We recommend that AES! perform a geotechnical review of the plans prior to final design completion. In this way, we can confirm that our earthwork and foundation recommendations have been properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundation system depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know, and we will prepare a cost proposal. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington Senior Project Engineering Geologist Attaclunents: Figure 1: Figure 2: Appendix: December I 6, 2013 Vicinity Map Site and Exploration Plan Exploration Logs Laboratory Testing JPUpc -KE130602A2-Projectsl20130602lKEIWP Bruce L. Blyton, P.E. Senior Principal Engineer ASSOCIATED EARTH SCIENCES, INC. Page 19 l > ~ ! ,! • 8 L. REFERENCE: USGS TOPOI H.Qis.: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS ANO LEAD TO INCORRECT INTERPRETATION . 0 \ ,, N A 1000 2000 FEET j Associated Earth Sciences, Inc. VICINITY MAP FIGURE 1 ~ WHITMAN COURTTOWNHOMES DATE 11113 ~ • I ::f.··I lliilJ ii lf!I RENTON, WASHINGTON PROJ. NO. KE130602A _________________________ ..;..;.;.;;.;;.;.;..;.;....;;;..;.;.~-- . ' I i j REFERENCE: GMSARCHITECTURALGROUP J j Associated Earth Sciences, Inc. 1•~~iilll i ! ~· ti! ., APPROXIMATE LOCATION OF EXPLORATION PIT SITE AND EXPLORATION PLAN WHITMAN COURTTOWNHOMES RENTON, WASHINGTON ,,.,,,,,,_, .J. N A 0 40 BO FEET FIGURE 2 DATE 11/13 PROJ. NO. KE130602A APPENDIX Well-graded gravel and GW gravel with sand, litlle to no fines Poorly-graded gravel and gravel with sand, little to no fines Silty gravel and silty GM gravel with sand Clayey gravel and GC clayey gravel with sand Well-graded sand and sw sand with gravel, little to no fines Poorly-graded sand SP and sand with gravel, little to no fines Silty sand and SM silty sand with · gravel Clayey sand and SC clayey sand with gravel Terms Describing Relative Density and Consistency Coarse- Grained Soils Density Very Loose Loose Medium Dense Dense Very Dense SPT121 blows/foot Oto 4 4 to 10 10 to 30 30 to 50 >50 Test Symbols G = Grain Size Consistency SPT12biows/foot Oto2 M = Moisture Content A = Atterberg Limits C =Chemical Fine- Grained Solis Very Soft Soft Medium Stiff Stiff Very Stiff Hard 2to4 DD = Dry Density 4 to8 K = Permeability 8to 15 15 to 30 >30 DescripUve T enm Boulders Component Definitions Size Range and Sieve Number Larger than 1 ~ Cobbles Gravel Coarse Gravel Fine Gravel Sand Coarse Sand Medium Sand Fine Sand Slit and Clay a~to12~ 3" to No. 4 (4.75 mm) 3ftto 3/4" 3/4' to No. 4 (4.75 mm) No. 4 (4.75 mm) to No. 200 (0.075 mm) No. 4 (4.75 mm) to No. 10 (2.00 mm) No. 1 O (2.00 mm) to No. 40 (0.425 mm) No. 40 (0.425 mm) to No. 200 (0.075 mm) Smaller than No. 200 (0.075 mm) (3l Estimated Percentage Percentage by 4111--+-----------I Component Weight Moisture Content Dry -Absence of moisture, dusty, dry to the touch Slightly Moist • Perceptible moisture Slit, sandy silt, gravelly slit, ML slit with sand or gravel CL Clay of low to medium plasticity; silty, sandy, or gravelly clay, lean clay Organic clay or silt of low OL plasticity Trace Few Little With Sampler Type E ast1c Si t, ayey SI , silt 2.0' OD MH with mlcaceous or Split-Spoon <5 5to 10 t5to25 -Non-primary coarse constituents: ,2:. 15% -Fines content between 5% and 15% Moist· Demp but no visible water Very Moist • Water visible but not free draining Wet -Visible 1ree water, usually from below water table Symbols Blows/6-· or portion of 6" I " " • Sampler Type Description <•> Cement grout surface sear Bentonite seal diatomaceous fine sand or Sampler --r=sll~t --------t (SPT) 3.0' OD Split-Spoon Sampler •• Filter pack with :":· blank casing :-· s&c:Uon Clay of high plasticity, 3.25" DD Split-Spoon Ring Sampler CH sandy or gravelly clay, fat Bulk sample clay with sand or gravel 3.0' OD Thlr>-Wall Tube Sampler Qncludlng Shelby tube) ·: Screened casing ."·' or Hydrntip ·: with flller pack _-. Endcap o Portlon not recovered (ll Percentage by dry weight '---'----,f#~'!---,----------j l2l (SPT) Standard Penetration Test , (ASTM D-t5B6) Peat, muck and other PT highly organic soils 13/ In General Accordance with Standard Practice for Description l4 ) Depth of ground water .!: AID= At time of drtlHng ~ Static water level (dale) !S> Combined USCS symbols used tor fines between 5% and 15% and Identification of Soils (ASTM 0'2488) i · Classlflcatlons of soils In this report are based on visual field and/or laboratory observations, whlch Include density/consistency, moisture condition, grain size, and· plasticity esUmales and should not be construed to Imply Held or laboraloty lasting unless presented herein. VlsuaJ.manual and/or laboratory dassllicatlon §; methods of ASTM 0~2487 and 0-2488 were used as an Identification guide for the Unlfled SoH Classification System. ~ ====================== i d Associated Earth Sciences, Inc. EXPLORATION LOG KEY FIGURE A1 i -------------------------------------------- LOG OF EXPLORATION PIT NO. EP-1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION FIii Loose to medium dense, moist, brown and gray, silty tine to coarse SAND, with gravel, scattered 1 -organics, burned wood fragments, plastic and rubber pieces, concrete. 2 - 3 - 4 - 5 6 - 7 - 8 - 9 - 10 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Buried Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown (5.5 to 6.5 feet) to brown, tine to coarse SAND, with gravel. Medium dense, moist to wet, brownish gray, GRAVEL, with sand, with silt. Bottom of exploration pit at depth 1 O feet Seepage at 1 O feet. No caving. 1;-----J,!6------------------------------------------- ~ --------------------------------------------'" j Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ~ -------------------------------------------- LOG OF EXPLORATION PIT NO. EP-2 g This log is part of the repor\,rrepared by Associated Earth Sciences, Inc. (AESI) 1or the named ftroject and should be a read together with that repo for comRlete interpretation. This summary ~plies only to the loca ion of this trench at the ¢ time of excavation. Subsurface condi ions may change at this location wi the passage of time. The data presented are 0 a simplfication of actual conditions encountered. DESCRIPTION -----------··-·· Fill 1 -Loose to medium dense, moist, brown and gray, silty fine to coarse SAND, with gravel, wood debris and scattered organics. 2 - 3 --·· -Buried Topsoil 4 -Vashon Recessional Outwash Loose to medium dense, moist, reddish brown (3.5 to 4.5 feet) to brown, fine to coarse SAND, with 5 - gravel. 6 - 7 - 8 - 9 - 10 - 11 - 12 -Bottom of exploration pit at depth 11.5 feet Seepage at 11.5 feet. No caving. 13 - 14 - 15 - 16 - 17 - 18 - 19 - " 0 ~--------------------------------------------,,; j " " I ~ Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc, ~ r--:::;;:-i El l:t""'ll lni<I ~ L.J:::J ~ In] in:.., Project No. KE130602A 11/21/13 ~ ----------------------------------- g i 0 LOG OF EXPLORATION PIT NO. EP-3 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be read together with that report for complete Interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Fill Loose to medium dense, moist, brown and gray, silty fine to coarse SAND, with gravel, wood debris 1 -and scattered organics. 2 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 13 - 14 - 15 - 16 - 17 - 18 - 19 - Buried Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown, silty SAND, with gravel. Medium dense, moist, brownish gravel, fine to medium SAND, trace gravel. Medium dense, moist, brownish gray, GRAVEL, with fine to coarse sand. Medium dense, moist, brownish gray, fine to medium SAND, with silt, with gravel. Bottom of exploration pit at depth 12 feet No seepage. Caving 4 to 6 feet. ~-----i2o------------------------------------------o N--------------------------------------------,S 1 J Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 g ~ -------------------------------------------- t 0 LOG OF EXPLORATION PIT NO. EP-4 This Jog is part of the report prepared by Associated Earth Sciences, Inc. (AESl) for the named project and should be read together with that report for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsuriace conditions may change at thls location with the passage of time. The data presented are a slmplfication of actual conditions encountered. DESCRIPTION Fill Loose to medium dense, moist, brownish gray, silty SAND, with gravel. 1 - 2 - Loose to medium dense, moist, brown, silty SAND, with gravel, with wood debris, plastic, concrete, 3 -and scattered organics. 4 - Vashon Recessional Outwash 5 -Loose to medium dense, moist, reddish brown, fine to medium SAND, with silt, with gravel. 6 - 7 -Loose to medium dense, moist to wet, brown, fine to medium SAND, with silt, with gravel. 8 - 9 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 1 O feet Seepage at 10 feet. No caving. w---j~-----------------------------------------§ ___________________________________________ _ • j ~ Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ----------------------------------- 1 - 2 - 3 - 4 - 5 - 6 - 7 - LOG OF EXPLORATION PIT NO. EP-5 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESl} for the named project and should be read together with that repqrt for complete interpretation. This summary applies only to the location of this trench at the time of excavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplfication of actual conditions encountered. DESCRIPTION Topsoil Vashon Recessional Outwash Loose to medium dense, moist, reddish brown, fine to medium SAND, with gravel. Medium dense, moist, brownish gray, fine to medium SAND, with gravel. Medium dense, moist, brownish gray, fine to coarse SAND, trace gravel. 8 -------------------------------------------- 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - Bottom of exploration pit at depth 8 feet No seepage. No caving. ~------l1:6------~ ~--------------------------------------------.,; j ~ I Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. ~ r_p ~ [T"ll ~ ~L.LJ~mlE~ Project No. KE130602A 11/21/13 ~ ----------------------------- LOG OF EXPLORATION PIT NO. EP-6 1 g This log is part of the report grepared by Associated Earth Sciences, Inc. (AESI) for the named Rroject and should be I E. read together with that repo for comRlete Interpretation. This summary ~plies only to the loca ion of this trench at the m time of excavation. Subsurface condi ions may change at this location wi the passage of time. The data presented are 0 a simplficatlon of actual conditions encountered. DESCRIPTION Topsoil Vashon Recessional Outwash 1 -Loose to medium dense, moist, reddish brown to brown, fine to medium SAND, with silt, with gravel, with roots. 2 - 3 -Medium dense, moist, brownish gray, fine to medium SAND, with gravel. 4 - 5 - 6 - 7 ~ 8 - Vashon Lodgement Till Very dense, moist, brownish gray, silty fine to medium SAND, with gravel. 9 10 -Bottom of exploration pit at depth 9 feet No seepage. No caving. 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 ~ M-~~--------------------------------~·--------~--------------------------------------------.,; I g Logged by: JPL Approved by: Whitman Court Townhomes Renton, WA Associated Earth Sciences, Inc. Project No. KE130602A 11/21/13 ~ ----------------------------------- GRAIN SIZE ANALYSIS -MECHANICAL Date Sampled Project Project No. Soil Description 12/6/2013 Whitman Court Town homes KE130602A Gravel with sand trace silt Tested By Location EB/EP No 'Depth MS Onsite EP-1 7' .434.87 · '424,21· 1385.2 323.6 1341.0 Moisture o/c • Jo/, • Soecification Reauirements Sieve No. Diam. tmm\ Wt. Retained rn1 % Retained % Passinn Minimum Maximum 3 76.1 --·, ··>~\.··t·:::' ... . . 0.0 100.0 -- 2.5 64 _·_",-. 0.0 100.0 -- 2 50.8 _ _. _· .. .. 0.0 100.0 -- 1.5 38.1 13.7.39 10.2 89.8 -- 1 25.4 41-0,38' . 30.6 69.4 -- 3/4 19 . 599,76 . . 44.7 55.3 3/8 9.51 7'07JS2 . ·-:-: 52.B 47.2 #4 4.76 780.38 . . .· 58.2 41.B #8 2.38 ·,· 901,93 67.3 32.7 #10 2 •: 9=·:53·. ~ .. ; .. 69.7 30.3 #20 0.85 . ,1,059;76 ·--~~-:!' 79.0 21.0 #40 0.42 ... 1213/W ----90.5 9.5 #60 0.25 '72':!StiCJ: 94.9 5.1 #100 0.149 "'"''1291,19 :;; ·, 96.3 3.7 #200 0.074 .;"·.1304,56 · . 97.3 2.7 #270 0.053 · ; · 13071018 .:. · 97.5 2.5 US STANDARD SIEVE NOS. 3" 3/4" N0.4 N0.16 N0.40 N0.200 100 ' ~k \ - ! ~ ~ ~ Li: 1: ~ ~ ~ a. 80 60 40 20 0 100 -- \. ' !!l...... ----·--· ~ -= .... ...... ......... ... -- 10 0.1 0.01 Gravel Sand Silt and Clay Coarse I Fine Coarse I Medium I Fine Grain Size, mm ASSOC/A TED EARTH SCIENCES, INC. 911 5th Ave., Suite 100 Kirkland, WA 9a033 42S.S27•7701 FAX 425-827-5424 Date Sampled 12/6/2013 Tested By MS Moisture% Sieve No. 3 2.5 2 1.5 1 3/4 3/8 #4 #8 #10 #20 #40 #60 #100 #200 #270 3" 100 80 - ~ ~ C 60 .. , - ii: ~ C ~ ~ 0. 40 20 0 100 GRAIN SIZE ANALYSIS -MECHANICAL Project Project No. Soil Description Whitman Court Town homes KE130602A Gravel with sand trace silt Location Onsite 424.15 . 40.3'07 . 98.15 304.92 7'A ' EB/EP No I Depth EP-1 9.5' Total Sample Tare Total Sample wt + tare Total Sam le Wt Total Sample Dry Wt -·r so.ss> 1056.6 988.3 Snecification Reauirements Diam. <mm\ Wt. Retained • n % Retained % Passino Minimum Maximum 76.1 "''" -·~·."·=" '::1:·~:.::::;-,.-.~:a:;, .. 0.0 100.0 . . 64 ' .. 'i 0.0 100.0 . . 50.8 ... ... -0.0 100.0 . . . ·-= "" ., 38.1 ,· -; 132:.!lf'. • · 13.4 86.6 . . 25.4 1t~rn4 ·;, 17.8 82.2 . . 19 .261.46 26.5 73.5 9.51 ' 458.66 : 46.4 53.6 4.76 617.45 ·, 62.5 37.5 2.38 ' 707.26 --·' 71.6 28.4 2 -725.86 ··:· 73.4 26.6 0.85 ' 806:jsl. ' 81.6 18.4 0.42 -::c-892:64.i ''' ·'. 90.3 9.7 0.25 '.· '941:52; -95.3 4.7 0.149 ' 954.51 96.6 3.4 .... ,. ,. 0.074 . '. 961.:94.: 97.3 2.7 0.053 ·._; .964'• ~--97.5 2.5 US STANDARD SIEVE NOS. 3/4" N0.4 N0.16 N0.40 N0.200 \ !lo,. ""' .. ~ '-"ii ~ .. r, !l, ~ ~ ........... ~i'o-. 10 0.1 0 01 Gravel Sand Silt and Clay Coarse I Fine Coarse ] Medium I Fine Grain Size, mm ASSOCIATED EARTH SCIENCES, INC. 911 5th Ave .. Suite 100 Kirkland, WA 98033 42~27•7701 FAX425-827-5424