Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
Misc
LE TAC O M A SEATTLE TECHNICAL INFORMA TION REPORT PREPARED FOR: Renton School District #403 7812 South 124th Street Seattle, WA 98178 PROJECT.• Nelsen Middle School Site Improvements Renton, Washington 211128.10 PREPARED BY: Michael R. Norton, P.E. Project Engineer REVIEWED BY.' Doreen S. Gavin, PE, LEER° AP Vice President March 2012 Civil Engineers • Structural Engineers • Landscape Architects • Community Planners • Land Surveyors • Neighbors TECHNICAL INFORMATION REPORT PREPARED FOR: Renton School District #403 7812 South 124th Street Seattle, WA 98178 PROJECT: Nelsen Middle School Site Improvements Renton, Washington 211128.10 PREPARED BY.- Michael Y: Michael R. Norton, P.E. Project Engineer REVIEWED BY: Doreen S. Gavin, PE, LEED° AP Vice President March 2012 I hereby state that this Technical Information Report for Nelsen Middle School Site Improvements has been prepared by me or under my supervision, and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that the City of Renton does not and will not assume liability for the sufficiency, suitability, or performances of drainage facilities prepared by me. TECHNICAL INFORMA TION REPORT PREPARED ICOR: Renton School District No. 403 7812 South 124th Street Seattle, WA 98178 PROJECT. - Nelsen Middle School Site Improvements Renton, Washington 211128.10 PREPARED BY: Michael R. Norton, P.E. Project Engineer REVIEWED BY.- Doreen S. Gavin, PE, LEED° AP Vice President March 2012 TABLE OF CONTENTS SECTION PAGE 1.0 Project Overview............................................................................................. 1 1.1 Purpose and Scope................................................................................ 1 1.2 Existing Conditions .................... ........ 1 1.3 Post -Development Conditions.................................................................. 2 2.0 Conditions and Requirements Summary.............................................................. 3 2.1 Core Requirements................................................................................ 3 2.2 Special Requirements............................................................................. 5 3.0 Off -Site Analysis ....................................... ............. .. 5 3.1 Downstream Analysis............................................................................. 5 3.2 Upstream Analysis................................................................................. 8 3.3 Off -Site Design...................................................................................... 8 4.0 Flow Control and Water Quality Facility Analysis and Design .................................. 8 4.1 Flow Control......................................................................................... 8 4.2 Water Quality........................................................................................ 9 5.0 Conveyance System Analysis and Design............................................................10 6.0 Special Reports And Studies.............................................................................10 7.0 Other Permits.................................................................................................10 8.0 TESC Analysis and Design................................................................................10 9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant ........................11 10.0 Operations and Maintenance Plan.....................................................................11 11.0 Conclusion.....................................................................................................11 APPENDICES Appendix A Exhibits Figure 1 ..............TIR Worksheet Figure 2..............Vicinity Map Figure 3 .............. Existing Conditions Map Figure 4 .............. Developed Conditions Map Figure 5..............King County Water Features Map Figure 5 .............. City of Renton Groundwater Protection Areas Map Figure 7 .............. City of Renton Flow Control Applications Map Figure 8 .............. King County Water Quality Applications Map Figure 9..............City of Renton Sensitive Areas — Steep Slopes Map Figure 10 ............City of Renton Aquifer Protection Zones Map Figure 11 ............City of Renton Sensitive Areas — Erosion Hazard Map Figure 12 ............ City of Renton Sensitive Areas — Flood Hazard Map Figure 13 ............City of Renton Zoning Map Figure 14 ............ City of Renton Sensitive Areas — Landslide Hazard Map Figure 15 ............ Flood Insurance Rate Map Appendix B Soils Information Figure 1 .............. Natural Resource Conservation Service Data Figure 2 .............. City of Renton Soil Survey Map Appendix C Downstream Analysis Figure 1 .............. Drainage System Map, Upstream Tributary Map Figure 2 .............. Drainage System Map, On -Site Figure 3 .............. Drainage System Map, Downstream Appendix D Summary of Drainage Facilities Figure 1 .............. Existing Conditions Drainage Basin Map Figure 2 .............. Developed Conditions Drainage Basin Map Figure 3 .............. Flow Control Calculations Figure 4 .............. Conveyance System Analysis Appendix E Geotechnical Report Appendix F Bond Quantities, Facility Summaries, and Declaration of Covenant Figure 1 .............. Bond Quantities Worksheet Figure 2..............Flow Control and Water Quality Facility Summary Sheet Figure 3 .............. Declaration of Covenant Appendix G Operation and Maintenance Manual Appendix H TESC Analysis and Design Figure 1 ..............Temporary Sediment Pond Calculations 1.0 PROJECT OVERVIEW 1.1 Purpose and Scope The Nelsen Middle School project proposal is to provide improved athletic facilities on a 29.54 -acre site located at 2403 Jones Avenue South in Renton, WA. Improvements include the construction of a new baseball field; new soccer field with asphalt track; ADA paths from the existing building to the new athletic facilities; landscaping; and stormwater conveyance and flow control facilities. The project site is defined as the 6.84 acres which will be disturbed for the construction of these proposed improvements. This report describes the analysis and design of the stormwater facilities. The 2009 King Country Surface Water Design Manua! (KCSWDM) and City of Renton Amendments to the King County Surface Water Design Manual (February, 2010), establish the methodology and design criteria used for the project. The King County Runoff Time Series (KCRTS) software program, developed by the King County Department of Natural Resources, was used to calculate runoff and design stormwater flow control facilities. The Rational method was used to determine conveyance capacities. 1.2 Existing Conditions The project site is at the existing Nelsen Middle School located at 2403 Jones Avenue South in Renton, Washington (See Appendix A, Figure 2 for Vicinity Map), King County Parcel No. 2423059061. The parcel is zoned R-8, Residential 8du/ac according to the City of Renton Zoning Map (See Appendix A, Figure 13). The project site encompasses 29.54 acres within the Black River Drainage Basin as delineated by the icing County Water Features Map (see Appendix A, Figure 5). There are no wetlands on the project site. According to the City of Renton Groundwater Protection Areas Map (See Appendix A, Figure 6), the project site is not within a groundwater protection area. The Nelsen Middle School facility is bound to the north and northwest by multi -family residences off of Benson Road South, to the southwest and east by trees and vegetation, and to the south by Spring Glen Elementary School. Site soils have been classified as Map Unit AgC — Alderwood gravelly sandy loam, 6 to 15 percent slopes, according to the WA 633 Soil Survey of King County Area, Washington, provided by the Natural Resource Conservation Service. Permeability is moderately rapid in the surface layer and subsoil and very slow in the substratum. Roots penetrate easily to the consolidated substratum 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 low. Runoff is slow to medium, and the hazard of erosion is moderate. See Appendix B, Figure 1 for data provided by the Natural Resource Conservation Service. The City of Renton Soil Survey Map, included as Appendix B, Figure 2, also classifies on- site soils as AgC — Alderwood gravelly sandy loam, 6 to 16 percent slopes. A Geotechnical Engineering Report was created in May, 2011 by Associated Earth Sciences, Inc. Subsurface conditions were explored by advancing 13 exploration borings (EB -1 through EB -13) to gain subsurface information about the site. Representative samples of subsurface soils were obtained from each exploration boring at approximately 2.5- to 5 -foot depth intervals. The Geotechnical Engineering Report is included in its entirety as Appendix E. Fill 000 Existing fill was encountered in all exploration borings except for EB -1, EB -2 and EB -5. The fill ranged in thickness from 4 to 31 feet within the explorations and consisted of loose to medium dense silty sand and gravel with scattered organics. Stratified Drift Sediments (Undifferentiated) All of the explorations encountered medium dense to very dense brownish gray silty sand with gravel and sand lenses and beds, with thick sand beds encountered in exploration borings EB -5 and EB -9. Weathered Tertiary Bedrock At the location of exploration boring E13-3, the stratified drift was underlain by a highly fractured silty sand with gravel, which appeared as "chips" in the bedrock. Where encountered, the weathered bedrock extended beyond the depth explored. Groundwater An observation well was placed in exploration boring E8-9 at the time of drilling to determine if a static ground water level was present and to measure its depth. On April 21, 2011, a static water level was measured at a depth of 33.81 feet. Groundwater seepage was encountered in a thick sand bed in exploration boring EB -9 at the time of drilling. Moist to wet soil was encountered at various depths within the existing fill, suggesting that perched water should be expected throughout the site. AHBL, Inc. compiled a topographic survey for the Nelsen Middle School property. This survey was used as a base map to delineate on-site drainage basins. (See Appendix A, Figure 3 — Existing Conditions Map.) The existing school includes a main building on the southeast part of the site, with athletic fields to the north and west, and paved parking areas to the south, northeast and west of the main building. Site topography is relatively flat to gently sloping, with a sloped grassy "step" which leads downward to the north and west to existing sports field areas. The ground surface continues steeply downward from the subject site, approximately 15 to 20 vertical feet to the north and roughly 25 vertical feet to the west, to nearby properties. A wooded corridor with areas of ponded water lies to the east. In general, runoff from the existing baseball fields and track along the western portion of the site moves as sheet and subsurface flow to the northwest to exit the site. Drainage from the northern field area enters a series of underdrains and is piped via tightline conveyance system to an existing storm drain manhole in the northern portion of the western field areas before exiting the site. Refer to Section 3 of this report for the complete off-site analysis. 1.3 Post -Development Conditions Upon completion of construction, site improvements will include a new baseball field to the northwest of the existing school, a new soccer field with asphalt track to the north of the existing school, a flow control pond in the northwest corner of the project site, site landscaping, an asphalt access road from the new soccer field/track to the flow control pond, as well as site landscaping. (See Appendix A, Figure 4 for the Developed Conditions Map.) In general, the engineered drainage for the proposed project will not alter existing drainage discharge locations from the site. Runoff from the new baseball field and soccer field/track will be collected in a series of underdrains and piped via tightline conveyance system to the flow control pond for controlled release to an existing storm drain line in the northern portion of the western field area. This drainage design is in accordance with flow control requirements for a duration standard matching forested site conditions. Pre - and post -development flows are discussed in Section 4.1.3. Calculations are provided as Appendix D, Figure 3 — Flow Control Calculations. 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Core Requirements 2.1.1 Core Requirement #1 — Discharge at the Natural Location Currently, runoff from the existing baseball fields and track along the western portion of the site moves as sheet and subsurface flow to the northwest to exit the site. Drainage from the northern field area enters a series of underdrains and is piped via tightline conveyance system to an existing storm drain manhole in the northern portion of the western field area before exists the site. In general, the engineered drainage system for the proposed project will not alter existing discharge locations from the site. Runoff from the western and northwestern areas will continue to move as sheet and subsurface flow to the northwest to exit the site with the exception of the new baseball field, which will be collected by a series of underdrains and conveyed to the detention pond. Drainage from the new soccer field will be collected by underdrains and also routed to the detention pond to be released to an existing storm drain line in the northern portion of the western field area. Pre- and past -development flows are discussed in Section 4.1.3. Calculations are provided as Appendix D, Figure 3. 2.1.2 Core Requirement #2 — Off -Site Analysis ANBL staff performed a Level 2 Downstream Analysis on February 1, 2012. The analysis included: • Defining and mapping the study area. • Reviewing available information on the study area. • Field inspecting the study area. • Describing the existing drainage system including its existing and predicted problems, if any. • Addressing mitigation of existing and potential flooding, erosion, or nuisance problems. Refer to Section 3.0 of this report for the full Off -Site Analysis. 2.1.3 Core Requirement #3 — Flow Control The Nelsen Middle school project site is subject to duration standard matching forested site conditions flow control per the City of Renton Flow Control ' ODOO Application Map (See Appendix A, Figure 7). This detention standard matches the flow duration of pre -developed rates for forested (historic) site conditions over the range of flows extending from 50% of 2 -year up to the full 50 -year flow, as specified in Table 1.2.3.A of the City of Renton Amendments to the King County Surface Water Design Manual. The flow control requirement is applied to the project site area of 6.84 acres. The hydrologic model used to determine flows and durations is KCRTS. 2.1.4 Core Requirement #4 — Conveyance System The new conveyance system is designed to convey and contain the 100 -year peak flow (calculated using the Rational method) for the proposed site improvements, assuming developed conditions for on-site tributary areas and existing conditions for any off-site tributary areas. The design and calculations for the new conveyance system are included in Appendix D, Figure 4. 2.1.5 Core Requirement #5 — Erosion and Sediment Control An erosion and sediment control plan has been developed for this site in accordance with Appendix D of the KCSWM. Extensive erosion control measures will be provided due to the size of the project and the slopes along the north and west property lines. Control measures will include limiting the area to be disturbed, temporary sediment pond, catch basin sediment barriers, silt fencing, temporary interceptor ditches with gravel check dams, and proper cover measures. 2.1.6 Core Requirement #6 - Maintenance and Operations A sample maintenance and operations manual is included in Appendix G. 2.1.7 Core Requirement #7 - Financial Guarantees and Liability This project will comply with the financial guarantee requirements in Renton Municipal Code Section 4-6-030, Paragraph J. 2.1.8 Core Requirement #8 - Water Quality Section 1.2.8, Core Requirement #8 — Water Quality, of the City of Renton Amendments to the King County Surface Manual States "A proposed project or any threshold discharge area within the site of a project is exempt if it meets all of the following criteria: Less than 5,000 square feet of new PCIS that is not fully dispersed will be added, and Less than 5,000 square feet of new plus replaced PGIS that is not fully dispersed will be created as part of a redevelopment project, and c. Less than 35,000 square feet of new PGPS that is not fully dispersed will be added." The Nelson Middle School Site Improvement project does not involve the creation of Pollution Generating Surfacing, and is therefore exempt from the requirements of Core Requirement #8 — Water Quality. 2.2 Special Requirements 2.2.1 Special Requirement #1 - Other Adopted Area -Specific Requirements The Nelsen Middle School site is located within the Black River drainage basin. City and County basin requirements will be followed where applicable. 2.2.2 Special Requirement #2 - Flood Hazard Area Delineation The City of Renton Sensitive Areas Flood Hazard Map (See Appendix A, Figure 12) indicates that the project site lies outside of any flood hazard areas. FEMA Flood Insurance Rate Map 53033C0979F, dated May 16, 1995 (See Appendix A, Figure 15) indicates that the project site lies within Zone X - Areas determined to be outside the 500 -year floodplain. 2.2.3 Special Requirement #3 - Flood Protection Facilities The project does not contain, will not construct, and is not adjacent to any existing flood protection facilities. 2.2.4 Special Requirement #4 - Source Control The proposed project is an educational facility; therefore, it does not fit the definition of a commercial, industrial, or multi -family site for source control purposes. 2.2.5 Special Requirement #5 - Oil Control The project does not fit the definition of a high -use site; therefore, it is not subject to oil control requirements. 2.2.6 Special Requirement #6 - Aquifer Protection Area The project is not within an aquifer protection area as shown on the City of Renton Aquifer Protection Zone Map (See Appendix A - Figure 10). 3.0 OFF-SITE ANALYSIS 3.1 Downstream Analysis 3.1.1 Task 1 - Study Area Definition and Maps Nelsen Middle School proposes to provide improved athletic facilities on a 29.54 acre site located at 2403 Jones Avenue South in Renton, WA. Improvements include the construction of a new baseball field; soccer field with asphalt track, ADA paths from the existing building to the new athletic facilities; landscaping; and stormwater conveyance and flow control facilities. In developed conditions, site improvements will include a new baseball field to the northwest of the existing school, a new soccer field with asphalt track to the north of the existing school, and a detention pond in the northwest corner of the project site. There are four distinct areas on the project site which are separated by vertical relief of between 10 and 20 feet; the existing school lies in the southeast quadrant at an elevation of approximately 430 feet; the southwest quadrant, at elevation of approximately 418 will be expanded to the north for the proposed baseball field; the northeast quadrant, at an elevation of approximately 407 will house the proposed detention facility; and the northeast quadrant, at an elevation of approximately 422, is where the new soccer field and asphalt track will be located. The entire project site lies within the Black River Drainage Basin as delineated by the King County Water Features Map (See Appendix A, Figure 5). There are no wetlands on or in the vicinity of the project site. According to the City of Renton Groundwater Protection Areas Map (See Appendix A, Figure 6), the project site is not within a groundwater protection area. In existing conditions, there are four discharge locations from the project site. Stormwater from the western half of the site primarily moves as sheet and subsurface flow to the northwest to exit the site at the northern and western property lines. Drainage from the northern field enters a series of underdrains and is piped via tightline conveyance system to an existing storm drain manhole in the northwestern quadrant before existing the site. This discharge combines with above mentioned sheet and subsurface flows exiting the site within 1/4 mile downstream. Lastly, a portion of the northern field area moves as sheet and subsurface flow and exits the project site at the northern property line. This drainage does not combine with any other discharge from the project site. AHBL staff performed a Downstream Analysis for each of the drainage paths mentioned above. Drainage from the portion of the northern field exiting the project site at the northern property line is labeled as "Path A", drainage exiting the site along the western and remainder of the northern area is labeled as "Path B", drainage exiting the site at the existing storm drain manhole is labeled "Path C". Following the point of convergence of "Path B" and "Path C", the drainage path is labeled as "Path D". (See Appendix C, Figure 3 for downstream drainage system maps.) 3.1.2 Task 2 — Resource Review The following resources were reviewed to discover any existing or potential problems in the study area: 1. Adopted Basin Plans: The project site lies within the Black River Drainage Basin. Requirements for the Black River Drainage Basin will be followed where applicable. 2. Drainage Studies: AHBL developed a Technical Information Report in 2004 for the Nelsen Middle School access reconfiguration project. 3. Off -Site Analysis Reports: AHBL staff has not located off-site analysis reports for projects near the Nelsen Middle School Site Improvements project site. FEMA Map: FEMA Flood Insurance Rate Map 53033C0979F, dated May 16, 1995 (See Appendix A, Figure 15) indicates that the project site lies within Zone X — Areas determined to be outside the 500 -year floodplain. 6 000 Sensitive Areas Landslide Hazard Map: The off-site slopes to the north and west of the project present a moderate hazard according to the City of Renton Sensitive Areas Landslide Hazard (See Appendix A, Figure 14). Requirements for Landslide Hazard areas will be followed where applicable. There are no wetlands on or downstream of the project site. Soils Information: Site soils have been classified by the WA633 Soil Survey of King County Area, Washington and the City of Renton as Alderwood gravelly sandy loam, 6 to 15 percent slopes (AgC) (see Appendix B, Figures 1 and 2). Associated Earth Sciences, Inc. prepared a Geotechnical Engineering Report for the project site, confirming the existence of fill, stratified drift sediments (undifferentiated) and weathered tertiary bedrock on site. The Geotechnical Engineering Report is included in its entirety as Appendix E. Drainage Problems: To determine if there are any reported drainage problems downstream of the site, AHBL reviewed the internet-based, King County iMAP Stormwater Map Layer set. No drainage problems were on record for the Nelsen Middle School Site Improvement project site or downstream of the site. The resource review determined no existing or potential drainage problems, existing/potential flooding problems, or erosion and water quality problems. 3.1.3 Task 3 — Field Inspection Path A On February 1, 2012 AHBL staff performed a Downstream Analysis of the drainage system receiving stormwater runoff from the northern field exiting at the northern property line. Upon leaving the Nelsen Middle School property, runoff sheet flows within the constraints of the Sunset Ridge Condominiums driveway approximately 575 feet to Puget Drive SE, where it enters the tightline conveyance system within Puget Drive SE and flows to the west for approximately 390 feet to Grant Avenue South. Stormwater is then piped to the north for approximately 1,075 feet where it is discharged to a ditch to flow to the northwest for approximately 2,800 feet to the I-405 right-of-way. Field observations found no evidence of drainage related problems (erosion, overtopping, etc.) along Path A. Path B On February 1, 2012, AHBL staff performed a Downstream Analysis of the drainage system from the western half of the site that discharges at the north and west property lines. Stormwater runoff from this area parallels northern and western property lines to combine at approximately the northwest corner of the Nelsen Middle School property. From this point, it travels west as sheet and subsurface flow approximately 335 feet to Benson Road South to combine with runoff from Path C to form drainage Path D. Field observations found no evidence of drainage related problems (erosion, overtopping, etc.) along Path B. Path C The point of discharge from the subject site for Path C is an existing storm drain manhole on the western property line approximately 260 feet south from the northern property line. From this point, runoff is conveyed approximately 285 feet across the Westgate Condominium property to Benson Road South, where it enters the tightline conveyance system on the east side of the roadway to be conveyed approximately 390 feet north to combine with drainage from Path B to form drainage Path D. Field observations found no evidence of drainage related problems (erosion, overtopping, etc.) along Path C. Path D Path D, consisting of the combined runoff from Path B and Path C, continues north within the Benson Road South conveyance system approximately 390 feet before crossing to the conveyance system on the west side of Benson Road South. Runoff is conveyed north approximately 100 feet before turning east and entering the private conveyance system on Montclair Heights Apartments property. Runoff is generally conveyed approximately 600 feet to a small pond. Field observations found no evidence of drainage related problems (erosion, overtopping, etc.) along this path. 3.2 Upstream Analysis There are no off-site upstream tributary areas that contribute drainage to the athletic fields. On-site, upstream runoff to the athletic fields comes from approximately 0.85 acre near the northwest corner of the existing Nelsen Middle School building and the lower athletic fields. See Appendix C, Figure 1 for upstream tributary areas. 3.3 Off -Site Design Frontage improvements are not included with this submittal. 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Flow Control 4.1.1 Existing Site Hydrology Area (Acre) Flow (cfs) Till Forest Till Grass Impervious Total 2- Year 10- Year 100 - Year 1.42 5.20 0.22 6.84 0.330 0.597 1.31 4.1.2 Developed Site Hydrology Area (Acre) Flow (cfs) Till Forest Till Grass Impervious Total 2- Year 14- Year 100 - Year 0 5.20 1.64 6.84 0.639 0.902 1.87 8 13000 4.1.3 Flow Control Section 1.2.3 of the City of Renton Amendments to the King County Surface Water Design Manual states that "all proposed projects, including redevelopment project, must provide on-site flow control facilities to mitigate the impacts of increased storm and surface water runoff generated by the addition of new impervious surface and any related land conversion." According to the -City of Renton Flow Control Application Map (Appendix A, Figure 7), the Nelsen Middle School Site Improvement project is subject to the Flow Control Duration Standard Matching Forested Conditions. The flow control duration standard requires runoff from urban developments to be detained and released at a rate that matches the flow duration of forested rates over the range of flows extending from '/x of the 2 -year up to the 50 -year flow. Developed peak discharge rates shall match forested peak discharge rates for the 2- and 10 -year return periods. Flow duration specifies the cumulative amount of time that various flows are equaled or exceeded during a long- term simulation using historic rainfall. Flow control facilities are required to mitigate impacts of increased surface water runoff generated by the addition of new impervious surface and replaced impervious surfaces considered a targeted surface. Because this is a redevelopment project with a construction cost of less than 50 percent of the assessed value, the replaced impervious surfaces are not considered a targeted surface. Additionally, flow control facilities are not required to mitigate impacts of existing pervious surfaces. Therefore, a flow control facility is only required for the new impervious surface created by the redevelopment of the track and athletic fields and the construction of the new walkways. Based upon geotechnical explorations, the site soils are not conducive to infiltration. Therefore a detention system is proposed for the project area. For the hydrologic model for the redevelopment condition, the underdrained area of the athletic fields are modeled as 75 percent pervious and 25 percent impervious per the 2009 KCSWDM, Table 3.2.2.C, KCRTS Cover Groups and Areas of Application. The Flow Control Duration Standard was applied to control the flow durations and peaks to historic site conditions for the target impervious surface area. The flow durations and peaks were obtained by modeling the targeted impervious area (1.42 acres) as forest till. Because the pervious area is not a target surface, it was modeled as grass, till in both the pre -developed and the re -developed model conditions. Flow control calculations were performed using Icing County Runoff Time Series (KCRTS). Calculations are provided as Appendix D, Figure 3. 4.2 Water Quality Section 1.2.8, Core Requirement #8 — Water Quality, of the City of Renton Amendments to the King County Surface Manual States "A proposed project or any threshold discharge area within the site of a project is exempt if it meets all of the following criteria: d. Less than 5,000 square feet of new PGIS that is not fully dispersed will be added, and e. Less than 5,000 square feet of new plus replaced PGIS that is not fully dispersed will be created as part of a redevelopment project, and 9 13c)(33 f. Less than 35,000 square feet of new PGPS that is not fully dispersed will be added." The Nelson Middle School Site Improvement project does not involve the creation of Pollution Generating Surfacing, and is therefore exempt from the requirements of Core Requirement #8 — Water Quality. 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The conveyance system was analyzed by means of the Rational Method in accordance with Table 3.2 of the KCSWDM. "Stormshed 2G" software was used for the analysis. The system was designed for the 25 -year storm event, and checked for capacity for the 100 -year event. A backwater analysis was performed for both the 25- and 100 -year events assuming a submerged outlet into the detention pond. Backwater elevations at all structures are below the 0.5 foot clearance threshold for both events with the closest backwater to rim distance of kXk feet during the 100 -year event. (See Appendix D, Figure 4 for conveyance calculations) 6.0 SPECIAL REPORTS AND STUDIES Associated Earth Science, Inc. prepared a Geotechnical Report for the subject site in May, 2011, which is included in its entirety as Appendix E. 7.0 OTHER PERMITS To the best of our knowledge, a grading permit and the National Pollutant Discharge Elimination System (NPDES) Stormwater Permit are the only permits required for the proposed project. 8.0 TESC ANALYSIS AND DESIGN The proposed development shall comply with guidelines set forth in the KCSWDM. The plan includes erosion/sedimentation control features designed to prevent sediment -laden runoff from leaving the site or from adversely affecting critical water resources during construction. The following measures will be used to control erosion/sedimentation processes: • Clearing Limits: All areas to remain undisturbed during the construction of the project will be delineated prior to any site clearing or grading. • Cover Measures: Disturbed areas shall be covered as required in Appendix D of the 2009 KCSWDM. • Perimeter Protection: Filter fabric fencing for ditch and site runoff protection will be provided at downstream site perimeters. • Sediment Retention: Surface water collected from disturbed areas will be routed through a sediment pond prior to release. Design calculations for the sediment pond are provided as Appendix H, Figure 1. • Construction Entrance: Existing driveways will serve as points of ingress/egress for construction related traffic. Sweeping and the implementation of a wheel wash will occur if sediment is deposited on on-site driveways or neighboring rights of way. Catch Basin Sediment Protection: Filter fabric protection will be provided on all new and existing drainage collecting structures downstream of construction activities. Surface Water Control; Interceptor ditches with gravel check damswill be used to direct runoff from construction areas to the sediment pond. Dust Control: Dust control measures will be implemented when exposed soils are dry to the point that wind transport is possible, and roadways, drainage ways, or surface waters are likely to be impacted. 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT To establish appropriate bond amounts, the City of Renton Bond Quantities Worksheet will be provided in the final submittal as Appendix F, Figure 1. Following approval of the engineering plans a Flow Control and Water Quality Facility Summary Sheet will be submitted along with an 8-1/2 inch by 11 inch plan sketch for each facility proposed for construction per KCSWDM requirements. See Appendix F, Figure 2 for an example of the sheet. Prior to permit approval, a Declaration of Covenant will be signed and recorded and will be provided as Appendix F, Figure 3. 10.0 OPERATIONS AND MAINTENANCE PLAN Operations and maintenance will be the responsibility of the Owner. All drainage facilities shall be maintained and operated in compliance with the City of Renton and King County maintenance standards. See Appendix G for the Maintenance Requirements for privately maintained drainage facilities. 11.0 CONCLUSION This site has been designed to meet or exceed the requirements of the 2009 King County Surface Water Design Manual and the City of Renton Amendments to the King County Surface Water Design Manual (February, 2010). The site incorporates flow control facilities to detain stormwater draining from the project site. Flow calculations/modeling utilized the City of Renton standards for sizing stormwater conveyance networks, and flow control facilities. 11 GIM03 This analysis is based on data and records either supplied to or obtained by AHBI_, Inc. These documents are referenced within the text of the analysis. The analysis has been prepared Utilizing procedures and practices within the standard accepted practices of the industry. We conclude that this project, as proposed, will not create any new problems within the existing downstream drainage system. AHBL, Inc. Michael R. Norton, P.E. Project Engineer MRN/Isis February, 2009 Q:12011\211128\10_CIV�NON_CAD�REPORTS\Tecjnicak Information Report\2012-01-23 TIR (Draft).docx 12 MID190 APPENDIX A Exhibits Figure 1..0...... TIR Worksheet Figure 2......... Vicinity Map Figure 3......... Existing Conditions Map Figure 4......... Developed Conditions Map Figure 5......... King County Water Features Map Figure 6 ......... City of Renton Groundwater Protection Areas Map Figure 7......... City of Renton Flow Control Applications Map Figure 8......... King County Water Quality Applications Map Figure 9......... City of Renton Sensitive Areas — Steep Slopes Map Figure 10....... City of Renton Aquifer Protection Zones Map Figure 11....... City of Renton Sensitive Areas — Erosion Hazard Map Figure 12....... City of Renton Sensitive Areas — Flood Hazard Map Figure 13....... City of Renton Zoning Map Figure 14..0.... City of Renton Sensitive Areas — Landslide Hazard Map Figure 15....... Flood Insurance Rate Map KING COUVJY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Engineer Company Phone ❑ DFW HPA ❑ COE 404 ❑ DOE Dam Safety ❑ FEMA Floodplain ❑ COE Wetlands ❑ Other ❑ Shoreline Management ❑ Structural Rockery/Vault/ ❑ ESA Section 7 Pdt F?LAN¢11±fDFI='�R. xli41114ONr c . l M Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review Full / Targeted / Type (circle one): Full I Modified I (circle)Large Site Small Site Date (include revision Date (include revision dates): dates): Date of Final: Date of Final: Type (circle one): Standard I Complex / Preapplication / Experimental I Blanket Description (include conditions in TIR Section 2) Date of Approval 2049 Surface Water Design Manual I 1/9/2009 R- KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET ❑ River/Stream ❑ Steep Slope ❑ Lake ❑ Erosion Hazard ❑ Wetlands ❑ Landslide Hazard ❑ Closed Depression ❑ Coal Mine Hazard ❑ Floodplain ❑ Seismic Hazard ❑ Other ❑ Habitat Protection Ll Soil Type Slopes ❑ High Groundwater Table (within 5 feet) ❑ Sole Source Aquifer ❑ Other ❑ Seeps/Springs ❑ Additional Sheets Attached 2009 Surface Water Design Manual 2 Erosion Potential 1!912009 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL. TECHNICAL INFORMATION REPORT (TIR) WORKSHEET F art 11s DRAINAz -E"DESIGN_LiMli" TIONS REFERENCE ❑ Core 2 - Offsite Analysis ❑ Sensitive/Critical Areas ❑ SETA ❑ Other LJ ❑ Additional Sheets Attached LIMITATION / SITE CONSTRAINT <T1F�SUN1MiARY.SHEET, . ': roVide:oneTtMrnrria: .Sheet perth oldDrschar eArea Threshold Discharge Area: name or description) Core Requirements (all 8 apply) Discharcie at Natural Location Number of Natural Discharge Locations: i Offsite Analysis Level: 1/ 2 1 3 dated: Flow Control Level: 1 1 2 1 3 or Exemption Number incl. facility summaTy sheet Small Site BMPs Conveyance System Spill containment located at: Erosion and Sediment Control ESC Site Supervisor: Contact Phone: After Flours Phone. Maintenance and Operation Responsibility: Private 1 Public It Private, Maintenance Log Required: Yes / No Financial Guarantees and Provided: Yes 1 No -Liability Water Quality Type: Basic / Sens. Lake ! Enhanced Basicm ! Bog (include facility summary sheet) or Exemption No. Landscape Management Plan: Yes / No Special Requirements_as applicable Area Specific Drainage Type: CDA / SDO 1 MDP / SP / LMP / Shared Fac ! None Re uirements Name: FloodplainlFloodway Delineation Type: Major / Minor / Exemption 1 None 100 -year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: Source Control Describe landuse. (comm./industrial landuse) Describe any structural controls: 2009 Surface Water Design Manual 1/912009 3 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Oil Control High -use Site: Yes 1 No Treatment BMP: Maintenance Agreement: Yes / No with whom? Other Drainage Structures Describe P�rt'73• EROSION ANDSEN357IENTCONTROL.RE6UIRWr_RTS.... MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION ❑ Detention ❑ Infiltration ❑ Regional Facility ❑ Shared Facility ❑ Flow Control BMPs LJ Other AFTER CONSTRUCTION ❑ Clearing Limits ❑ Stabilize Exposed Surfaces ❑ Cover Measures ❑ Remove and Restore Temporary ESC Facilities ❑ Perimeter Protection ❑ Clean and Remove All Silt and Debris, Ensure ❑ Traffic Area Stabilization Operation of Permanent Facilities ❑ Sediment Retention ❑ Flag Limits of SAO and open space LJSurface Water Collection preservation areas ❑ Dewatering Control LJ Other ❑ Dust Control ❑ Flow Control Part 1'STORM11tlAT R FAC1i 1T DESeRJP!I0N Nbt+e' iiddrfe 1=ap�li Sutxli ariit Sketch :. , . ; Flow Control Type/Description Water Quality Type/Description ❑ Detention ❑ Infiltration ❑ Regional Facility ❑ Shared Facility ❑ Flow Control BMPs LJ Other ❑ Biofiltration ❑ Wetpool ❑ Media Filtration ❑ Oil Control ❑ Spill Control LJFlow Control BMPs ❑ Other 2009 Surface Water Design Manual 1/9/2009 4 KING COUNTY, WASHINGTON, SURFACE WATER DESICN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET .: Part 15 EASEMENTSITRAiTS Part 16.::. STRUCTURAL ANALYSIS ❑ Drainage Easement ❑ Cast in Place Vault ❑ Covenant ❑ Retaining Wall ❑ Native Growth Protection Covenant ❑ Rockery > 4' High ❑ Tract ❑ Structural on Steep Slope ❑ Other ❑ Other I :R ..art 17. SIGNATUItE;OF PRt3E1=SS9ONAL''ENGIIVEEf;�, I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. 2009 Surface Water Design Manual 1/9/2009 5 VICINITY MAP NOT TO SCALE *ABBE NOT TO SCALE CivdEn�,aea vtZZ55urasl EnpF�eera E:lc +.soe.ad�cs Camuar Pbvme T A C a V A S E A T T l_ E 2215 North 301h Streel, SURC 340, Tocama, WA 96403 253,383.2422 TEL 1200 6th Avenue, Suite 1620, Seattle, WA 900 206.267.2425 TEL N solo jr AS Ono A y I � m l � > t •- '} f t r / I �fJwr, I` r f '� ♦ - �'- r :& 'yrl'5o1 �� -i y f `_�'� l : +fir 4`I• t r ' // - } l e E£� � All.+ f •- 'Vyl 1 F IL v NJ qj L._ r �^ I •}F � _ ` -. ", � `, y y � �Y � � � -r .gyp „ L1 t_..� � i ���-�� �E �': f #moi _ - -"L � F ti• � 9 v '� ''r a c� ��>` I,i ' -_� ��- �K 1 rF x.. v I ' L Wad aoo c oo� csc c paE} pow l 4 auoz j, nby aoinos o!os Aai!en �� epa;::.: a��a R1? �pj ueuis;eog '� `s4113 'd'uos��M •�' euoz eajy aoinoS magweailS t uo�s!niQ 2UIJaauiu3 sauoZ eaJa uo43aaoad aajinby ea.JVMOfAa-8 10aFoad jajinby ',i4f Mnia;eM au07 aan;deD JE@A ual T� aainoS aloS A8lleA aepaO �,_,_`luaw; isdaQ s�ao �iignd :. i auoZ ajnadeo Jea,, anis au07 ajnjdeo aeaX aup sfuudS �mg6uudS N sauoZ ainideo p1a1111aM " IIaM uo!}onpoad uolu;)-d jo X.1D ;)Ill ui SvZ)jv u01133joij lNumpunoij) E]- � � a UE)JeJa�:j C. SE)J! ' o d deN uoileoilddV joiluoo mou N �- I. GOuejejq-�-] %06< Irl®.. e spWil AID (J0}LIO� ®Y��1 sa�iniag I�iu�{�a�'swa}s (S sal�!Illfl's�{SaM�I}qnd :aa�no� ll %06-> g °/a0�� 600 ' l Z Am uo p81l 'aiupOaW '2i °f°Ob=> 3a1e.gsIL1Iwpy'ueuoa9u WlZ E:) . ooa z aob t o ;Ual.l.lj.,1SAjOM oI,qnd of l 8Be4u83Jad sedo{S daalg x � R II - I x s,m u •�, . �y„ ' tA ,f I p I uoi M >' :I s::w av it 'I°s'YFJ, o� i i r• : 1m isw fI - - .',r'F I � �� �� :� ��1� � s � � e � •�.• II !�il'.x t II I •3 'I,E F ilr d �� '• ..,,es'� ''_�.. 3 . .�.,;5., g �- ;�` I�� I :' I:x •xl I' i'I, ! '' � 'uasf �, � � I � � r . ✓... I_j� i Illi, I li S , #I '._ { u. 3% IJ' 11AT '.l I .... ! I;.. s ti, vee I{ IISII . - f1 Ni 'q�..` -`ram I - � _$ ..� +Y i�.M I M 1 :.'.� �(.}; � l3�y � '•� i F � �. l' i M 1 I A 4 s .;� 'f i4`'� P i, „Ifi �.: `T��' �,�` �2 � ��-: ';�w..w-.s 11.-'�5 � - 4- �. � .♦ � i ,c..a� �- sw.� i N t Y _7777r I''=' l 7 J� JI 1 1:. �a.�w�+ � R ` � I : Y I - � _ �'�► d7!'�:�i .�� 3 'F I � - �, <>t: '-�. � � / 4�s � � ` M:R � _. �• s,oc: is - _-■arrra� ■--.'� es-. �.�",; ,_ y _ • h � M� I �t— J r� L � �•� `} �.K � - e ..J�1 + I I � .,,.. �' �'i �� 3.• IU.; ,! y __ ,-. LI I, II� j$ � 'i u.� , '"'',� i ira�-r .K 7-1 Olt LI, " t - r ` - ^ I� .1 IIS I�,+y. I w"x x If _ � r I. ti'- r i 3 3 r [ '• s AL t III. 11� 10,� I II � �', � ,- Ir I I � Ig . :♦ r j - 1 F '"'! I '.u" V'a i' 3'+ l'-" e'' _ I' - , I ��.s t I .rl s - �;� I � s,:.�" I: L ff - f-l� 91 1� � � I a 53 •, Iz iL -i >: 1' I , } 116 Y L rte:. 1 I a M' S - - "::I � _ I— , F.'� �>., I � i .� SII �.. �' , � I w� - -,,� � �7�{ � v.:..<.: � .r ' ��sRLM�i'�*, E �,- •� I 1 I � "_ V ��� I ,�I. IT .� _ 'I r` Dir i u� 1 ,'y'�I y > v 1 •s-y.�;. d A�s- IIA 65 r,�'4� "Y 3. - .. itml ':T } i .d, S� !I�' 1 _ i. .. F• i' -4. i Yi'4�' 3,s`s.. 'Y' CF.: 1 Lue aii.9.3 - II _ ^i• -iiG ki4 �f1 I p r. I�' zld N7u�, k 3r x - _ I,:'F ...,r� '7•r 7 �1' .1'. s'a `�q�, + .. r•a� l I 1p�R �} � k k I': 1 I� ! ' f ?:; "':. -ai.,+ orR b' I li d S 1 � - ," - r r �n r � Ao rr e ,�' t _, r ✓ �3 � }'A r-""� '_I. �� It►ba �_ n --' I h! -- x ?� r.'3a�� '�Y & �s ;s.r'^3, �[ � r, �. hz �'}2 '� , •bF^" '1rYl 'a 1.- , �_ '.. �! AIL S zz .Rl }J �rT%� L` ye% F 4 1ti W- i .,i. ;, t .x - -, �I'-�y"wgµ(� 'i y u •\ li' y Fry IT sadoig aaalg SeE)J)V E)AIIISUE)S uo;uab;o Ain 01—V 411111 Aj!o Z ouoz L auoz OLJOZ -z ii -down- uolue's-i 9()0Z 'ZZ fienuerI Nr N sausA,C] -aluomiN -H sVoM . oqqndj1Juiplln6/6u4uueld + + Q S3NOZ N011O3102Jd 2i3J1f1 `d fj —V slnnt{aS I� aalua:) Ie��paVV halie� �m� suogeag a�l� _` - �uaufVedaQ a�lloa prQ xCF{ �o,xu13 - NOUIGNOO (R:1VZVH ._rte Frye sxr,Nnd Felrlsp I.I:,� .aI VPVu.l:,l si oPw s:yy uxa,ls alx01s1 lQ si14iuns �I V� I .Pr.6 you'ualen�xa,ea, N4dud e:: waur�=: siµy aao'c uu; ' }o 4 ) sa�ln�aS le�iuuael'su�alsl[g sailll!]fl `si{�o�t�gnd .aoanog eleQ 60oz ' Lz Aen uo p2Iuiad �S3 '[Asausin uueeuuop saOinaas yeoiuu�al aojejasluIwpy 'uewjawwlz 9 }uawpeda❑ sNjoM oilgod 4.. -_r 'fir'■ m , I �\ �' s a �➢ I � I � _ �� �� a i�, � iy 1 I 1 - I m _ " it Vl nrrr: 3s iiuY rm � IJ • - " ,s •.r 3L ... _ � - f 111 n d b-' 3 s�.,rs, 'war.- - ,..; x'. ,. ,> s �,,.,•PLI �� - - ucgLls li ,eA mc. v o„ ra, " • - so wuoi,,:m �s ;. �:� , .,•, .. L -i i 3�1a I Y _ 1 5'my } 4. �� I I TT'a +ev'•P, F' I t '� u..t-..s I.` •.L...s -., ➢ II l- _'I �. `"y - _� e P 1' 'I� II I 1 3 _ I s' y .,,I = •1 A I::. y� s Y �ve °L �T i w �.:a o- if ➢'�� 5 !� - a"g, - 4 awl V I i�! JV ,r ¢, ,'=;� �. X11,..° w .- - - ,� - IT _ � ,�I =�s'yk -a•.er,s � i '.?\ _� - ' I I,_ e rr� r 1. � I � •5 1 .y i liva r~ d ... -.. a ., �+ -. N -.�➢, i"'b,, ,.' �.. sw+ '� .. . , � '�" a s r,s.1 - , , .-� � ��\�•! �„' 1 s,s3,u ` I:,; 6 11 s 1 1 11 IA rw'..-c' - I� I'9 31u ---I II �' 1.. "-�`''"r ,•!}°�,r ` w�. 1 I ➢ •' '°e �'-- !� I�' ;a . x � If a '� - _ Y v ��-.:. M III v � I "Y ',w,u� .. ._�,�,� w.� - a � -1 „I, til,- -. - _§Y '>�hi�.rt'�tr- ���""`r. •. � ,� ,, . _ . 4'�.is, ,� � I -:p � ' �. 1-� '� � rt° �\ '.Y., � - il� I ��-➢ I` �,'?l"fRrr�,�,� y'� ? `{'1W6 , ;4.. .. r:,s ; .sir ' . - i+ a ' - •1 re... I " � 1 � I N:. 1\ \ � "l:+r,r � Ii _. - ° d � _ V N Ir�P I R� �..e 3,rLt�I,:�,;ll� sle,:r ''I' r„ ✓� r r ji _� � -1 1 s r II � !�� 1; 1� � �41� ,7 31`p °h `a 1=�;➢:I� a ``,.b 5 s � 1 `d a.r >ti . x �'1f 11'I� +% l� i s �.. i �'I, 3 �''_�-� K 'i ¢ I '� � � ,� :�r�I='s _� !ik rw".rPr.P'�I: � 1 Ir -, s^s fi:+'` �4, :r•..r�. ,s Y MIS Z n 1 ,.'E " !� .. 1 da,e 1 �. x a,`• >„.; a+ Y' I,5 '�� 'I__"I� . I° "' �� sw<,tu• 1 b { J ;- P _- - —,rr •i 3s- _- _.. � aro,]: f� i 1-x I� q �e•.�s 1 -_x� a 3.SIF i Y p w f ¢ F : -I S i are 3+ t" �'}5 f ;y,>, � � � Imo➢ �, I u� � � d%jt,➢ � � ' i. s � y ;� ���. # I - 4- 3 P ,P, 3 1 I! fi is �i j. 4 - I � IN s u s L� 1 � �iX � Y 4 � q�N b �6'•+.I . '7'3�• YA t~ PW. 3 r spaezeH uoisoa3 S139JV @A111SUE)Si10 AI!O 4 iz qK S 'err '� r. W Y � 4 r � spaezeH uoisoa3 S139JV @A111SUE)Si10 AI!O 4 -.j u1jd t, p- (30oz �z Aev� Ljo Pal 4u;:�Wpeic!61(1 ;9011cdaluooevq PIEZE?H POOIA !�Saus)A G ccu'z OOP saa)OJOS jcaIULOOL ainjonilsellul JE3111JO U0141PUOO WezeH Jojejjs1u1LuPv,uewj@wW1Z !D juawpedOC) S�joAA ollqnd z -q Mrd 40 le. t.k" J, rh V J 7 A .4m- 1e:N r b .�''` 4�C WJ V }� 3 - -z to lo A it Cc 41 141 4 114 it Jd q 10 1, K 7, tt.. f i Ie 11p k Mie, If 1_7 ij, Aj ii7 I.: 5A 11 V -2 —Z V L: 4 RIP �3!1; If paezeH pool seaay anilisuas UOJUG� 10 A}i� -7 . . ....... . Ue0(JL;3.a_LRUIUUEld LpIALjLLjeAqv sueupv 1 Al!unLLJWOZ) LjOD3 dQ[3Aa(3 DILUO juaLu jI 00 IL d J9 Se ONIORVa PRE qouwujpo k X �Aq P�iepdn L 1\�� I j q _J'. S -N '77.. J7, Law T q, tj llrr ii Y. 3� Lim 01 ij .1 1 F I .4 Y j! - j1j1 r r t! m j; 'T -,v I i m 'A (I i 1, z A t a.0 2 CA L It W, INA t. all NO -L o 4 ' q ' . -1 , . I - k] tM y F. IL Vd 1! jr 17 R, Ir �Z7 qqjii F- Is? IeyuepysaeTaal;4p�l�l�iewwo� (2j4]! . . . . . . . . . . ps't m4lwseb Op L -2J) In uojurwcj '*Wo5.(cjo1 SWAMM P-MkM -PIM ISCUE'N"m (KVIN) s. f,soHII?y4enPu[[HU z 4poN jolueo umn (M -0n) ulnlpeVq ;m4snpruj.(Vjj) t 0914 ja'",a ueqjfl (4N-00" oaff" 1114"WQ24 (8 14B�j j%ijrnpj (11) a" IA Anut) Ila P00410qLI81qN lowaujuipo (wo) Iwo sjpq Apo UOIU88 A{ ll sloogos aa;ueo feoipavy AalleA paLAssellaun a;ejapoyy slum;e;g all—A s} uxi� t(}a uo}uad -= 1461H A edaa aailo y6iH �a ,'�:u, ux �: A',`:aw, e.• ;uaua}� P , :�d,o ,o„ aca�do,ol�do6enoo..,voacpu �(;�a arias • S31111i�b'� JV3111 O O-dVZVH 3411SaN'd1 oas z Lsa o elf i�� rr x. a'a 7,7 !- _ , ! YY I t Clig I w i M l 1 I ice`---, �� ,��rn-i�� s I��If - I �.�„ r ( 1 ,r IBJ \\ , �Z 11 ,L , ,,k,7 .-"W 3''lI,x x} -•K� �I II ,x-11 "1 JIB 1 1r1 rr 3 f r j 1 L 1} j ? I r l r r� al I V Ji11 y!l S^lk��� ~`� t��� - ►_ ��/� j�'� ... � � �I� } �:�� ��z � IIT la 71 J'JIB j tl Ie• l II - Il li I ���A I I _ __�`p�-.>� '.`y 17i ��3�y� T�I WMM �o �,I�r Ji pn IMS _,� ,l�- � I� �. _ —r ..� �` IIr11 F_ I. ..r�� }♦s;4x_��J�`"� �,_ __.����C.��°} .-5��'J „::�IV'l�Jr`y� �I_ J 'fig ..[ 1L���''` {�l #g�"L_I u! rd r Ji r r r Il • �� � FI lung ss E �7i—J _�i—."'�.�_��9J II� 1 t _.JP_ A—L qq,�� d 1 F !r' \ %� __r�--,�' �ol � ift ,��'1 i / �� it I_�uik UF W111 J sao,NaS IEjlugoei 'swaj,AS s.!jgj;n 'sjjopy allgnd aounoS t -4l 60OZ ' l,Z fieri uo pa}uud Nsaus'A .(1 'aiuooen 8 saOIAJaS lea)uyaeL .lo1eAs1u1Lupy'uewjawwlz 9 juawpuda❑ sjjoM oi{gnd r,. �,,,1 F ':R �-gig �� �,,,... �/` -IIs ,•1 � � IIS Ire � x rll Y' �� �.� k�._ ...� 1 , 3 �•; � � 1 �%tjL 7J��a, \ ]�. — —i , fl 1l zL W „ ��1 i a ):.•r� IL �jL .a t':. �'. '��Ir �` 3�q- IIY I ''#F""'� a'zr�,..5>�' >Y� J �I fir- -r si'".v (�4wsa.. � f�J'^��Y mm , f� \ �., gill I�'�al�IIIC. t NJ,1, yl i R rj PJezeH 9pi1spue_1 r1 _9 I seam GJAIJ!SUE)S uo;uab jo Ain USDA United States Department of Agriculture �0� NRCS Natural Resources Conservation Service A product of the stational Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for King County Area, Washington January 23, 2012 5-1 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://soils.usda,gov/sqi/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (http:/loffices. sc.egov.usda.govllocatorlapp? agency=nres) or your NRCS State Soil Scientist (httpa/soils.usda.govlcontacU state—off ices/). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Soil Data Mart Web site or the NRCS Web Soil Survey. The Soil Data Mart is the data storage site for the official soil survey information. The U -S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (toot all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Contents tt=. Preface ................. ........... ............ ................ ......... --- ........................... --J How Soil Surveys Are Mmde—........................ ---...... ........................ ........... 6 SoilMap ............................... .................... ....... ..... .............. ............................... Soil Map (Nelson Middle Gchmo)—............. ................................ ..................... 8 Legend --------------------------------------0 Map Unit Legend (Nelson Middle School) ........ —.............................................. 10 Map Unit Descriptions (Nelson Middle SchooU—......... ............ .......... —... 0 King County Area, Washington, .............. ......... .................... ....... ................ 12 AgC—Aldonwoodgravelly sandy loam.Sho1Spercent slopes ...... ............ 2 References............... ----................ -------............ --........................ 4 Haw Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity, Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil -vegetation -landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color; texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the Custom Soil Resource Report individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components, the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of reap units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil - landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil -landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded, These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field -observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 0 5 m a C — C_ m N N @ V oor m a 65 m C C T O m U > O O O -C L N m i N U U Ul N w O N CL Q Uur N �U C? c U NLl Z tv E _w m- a m W O U <% (h cn V O Q x a m a m t_ a m y ro i� (� L rn in `m N E m� m N 0 it z m o cLi E� Q o a E o E 0 m c 0 Z N a o v " N Q m N r- !6 d L m E O ❑ (�] - N m cv t Q t6 �: C N C �Gy LL N m R E U cz N O d m O_ d 'O O C 0 7 O C L L 741 C LLL a ar m m n —✓>o Cm c o Ngo �aN 3 o0 eta oc o a T E ma a m Z a mm L Q - U m N N L J (R N N 00 � a worry b ZjE c- on o0 6? m E E L L T D �� i6 i9 O� N� o a L a c w Q y i N y m E o ? '6ca p cro�o o cm �U� C o Q� m �� N 7 C!J a5 y- U �'E ) C 2 � C �? r° c i 0 E a E ��m a� v, m c°i U) LE `oa d y U) d " ani a o 'p m CL m t m m 0 C m �= m m v d �� o o d o y � P 7 m t0 a - E m E F w E a w d E co 0 L I- w U) U) 0 �E° .� o n m n w 6 G � U w T r6 r (n q B o � s E o 0 T 7 O 75 c 0 LO D i 01 v, c L w+ d 4ti}, } T LL IX _ 5 W CL _ m C [ 0 w J a o m m m a a = m a a❑ r co 'a w o w Q c o a o a c n m a O w , a ro O i N_ rC O C CL co [0 U U V C? J J TL d C 0 V7 U) Vl 0 [n co G7 m C p• i � a ®x o o > + m to 4 m i Custom Soil Resource Report Map Unit Legend (Nelson Middle School) 147np:Counly.11rea, Washingtori.(WA533)'. -JAap unit Symbol; #ilap link NameAcrss in AOI Percent of ASI.' AgC Alderwood gravelly sandy loam, 6 to 15 7.7 1 Q0 0% i percent slopes Totals for Area of Interest I 7.7 100.0% Map unit Descriptions (Nelson Middle School) 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 noway 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 10 Custom Soil Resource Report intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately_ The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha - Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 11 Custom Soil Resource Report !Ging County Area, Washington AgCAlderwood gravelly sandy loam, 6 to 16 percent slopes Map knit Setting Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost -free period: 180 to 220 days Map Unit Composition Atderwood and similar soils: 95 percent Minor components: 5 percent Description of Alderwood Setting Landform: Moraines, till plains Parent material. Basal till with some volcanic ash Properties and qualities Slope.- 6 to 15 percent Depth to restrictive feature: 24 to 40 inches to dense material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table: About 18 to 37 inches Frequency of flooding. None Frequency of ponding: None Available water capacity: Very low (about 2.5 inches) Interpretive groups Land capability (nonirrigated): 4s Typical profile 0 to 12 inches: Gravelly sandy loam 12 to 27 inches: Very gravelly sandy loam 27 to 60 inches: Very gravelly sandy loam Minor Components Norma Percent of map unit: 1 percent Landform: Depressions Bellingham Percent of map unit: 1 percent Landform Depressions Seattle Percent of map unit. 1 percent Landform: Depressions Tukwila Percent of map unit: 1 percent Landform: Depressions 12 CUStOrn Soii Resource Report Shalcar Percent of map unit: 1 percent Landform: Depressions 13 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00, Cowardin, L.M., V. Carter, F.C. Golet, and E.T_ LaRoe, 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWSIOBS-79131. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurl, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands Characteristics and boundaries. Soil Survey Division Staff 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http:l/soils.usda,gov/ Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:l/soils usda.gov/ Soil Survey Staff. 2006. Keys to soil taxonomy. 10th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:l/soils.usda.gov/ Tiner, R.W., Jr. 1985. Wetlands of Delaware U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section United States Army Corps of Engineers, Environmental Laboratory. 1987, Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1 United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http //soils.usda.gov/ United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http:llwww.giti.nres.usda.govl United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430 -VI. http:llsoils.usda govt United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 295. http:llsoils.usda.govl 14 Custom Soil Resource Report United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. 15 APPENDIX B Soils Information Figure 1......... Natural Resource Conservation Service Data Figure 2......... City of Renton Soil Survey Map 600ZlZZ.1Z6 I.W oiaasoa 1a(] .;. rCNian as}eM a�e}.irls � s)aoM o!land p sP w auoZ 2a�y uo�alad aa}nby �d Q auoZ ealy uapalad lalinby . . ,4epunog easy uoilaalo3d jaaernpunme � deLN CananS IpS � � � � �:] 10 AID 0- L � aQuaJa18�j APPENDIX C Downstream Analysis Figure 1......... Drainage System Map, Upstream Tributary Area Figure 2......... Drainage System Map, On -Site Figure 3......... Drainage System Map, Downstream m it Y ;4Y dr m it Y m no a M IM" . . W� ut 3C-:) R4 m R4 m . iid N4 grkQ _ i y Oil` l I r K k y ox d !dam yy� �8 t is p Y k S C) LU v}} ` MM e Y ;' �rff su I-j`4b� ti3 1, R 3 LU ggyy pp I . iid N4 grkQ _ i y Oil` l I r K k ox d !dam yy� �8 �j S C) LU v}} ` MM e Y ;' �rff su I-j`4b� 1, R 3 LU ggyy pp I N� y F;�L h1 r F . iid N4 grkQ _ i y Oil` l I r K I d !dam v}} ` e Y ;' �rff , f V£•a 3MIlHOlW �I i � ■ i ® � i � ® � ® � � ® ® ® ® ® ® ® ■ i a ® i 0 ■ i ■ i d !S i 4 1 Lu ih- ® srJ ` ■ Z o 0 zz v C.7 W uj 1 �i W i ■ z — I. W w +u ■ Q � Vy ff LLI , ■_i CL 4 i ■ ii I ■ W � � T.. 0,{ 09 ■ ■ ■ ■ ■ ■ ■ ■ I ■ s k ■ I ■ ® I' I I M. LLI N■ Z■ I V H i ■ I lllc_ I AiPPENDIX D Summary of Drainage Facilities Figure 1......... Existing Conditions Drainage Basin Map Figure 2......... Developed Conditions Drainage Basin Map Figure 3....n.... Flow Control Calculations Figure 4...0..... Conveyance System Analysis Project: Project Number: Task: Date: Performed By: Reference: Design Criteria: Software Used: KCRTS OUTPUT Historic Tributary Area: Nelsen Middle School Site Improvements 211128.10 Appendix D, Figure 3: Flow Control Pond Calculations March 2, 2012 Michael R. Norton, P.E. 2009 King County Surface Water Design Manual and City of Renton Amendments to the Icing County Surface Water Design Manual Match the flow duration of pre -developed rates for forested (historic) site conditions over the range of flows extending from 50% of 2 -year up to the full S0 -year flow. King County Runoff Time Series (KCRTS) Historic Flows: Land Use Summary FAre.a Till Forest] 1.42 acres; Till Pasture! 0.00 acres Till Grass 53.20 acresi Outwash Forest 0.00 acresl Outwash Pasture! 0.00 acres 4 Outwash Grasse 0.00 acres Wedandl 0.00 acres Impervious 0.2g.acresi 6.84 acresl is . _..... _.. .. i Scale Factor: 1.00 Hourly Reduced Time Series. predev 4 Compute. Time Series Modify User input File for comported Time Series [.TS.FI y �£.vkR3'aRti�t)F".'9.D'S..e'..RwIYHRSR.6kYi�d�F63Af#VtMN +LH TW=M`P:-Wd'M11?FIG'�`T?W6M°VYvTM:WF`.k%AifYW3Y'v16yIGSYe1�.n- Historic Flows: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 1 100.00 0.574 4 2/09/01 2:00 0.308 7 1/05/02 16:00 0.711 2 2/27/03 7:00 0.152 8 8/26/04 2:00 0.330 6 1/05/05 8:00 0.597 3 1/18/06 16.00 0.536 5 11/24/06 3:00 1.31 1 1/09/08 6.00 0.231 0.152 Computed Peaks Developed Tributary Area: -Flow Frequency Analysis ----- Peaks - - Rank Return Prob (CFS) 0.00 arse Period 0.00 acne 1.31 1 100.00 0.990 0.711 2 25.00 0.960 0.597 3 10.00 0.900 0.574 4 5M 0.800 0.536 5 3.00 0.667 0.330 6 2.00 0.500 0.308 7 1.30 0.231 0.152 8 1.10 0.091 1.11 50.00 0.980 Land Use Surryn. FArea -- Till Forest, 0.00 i Till Pasture; 0.00 "fill Grass! 5.20 Outwash Forest' 0.00 Oulwash Pasturek 0.00 arse Outwash Grass! 0.00 acne WeNand 0.00 acre ImDervilousi 1.64 acre r- T" 5.84 acres Sole Factor, 1.00 Hourly Reduced Time Series: d? Compute Time Series Modify User Input - F__ - Developed Flows: for computed 'nme Series [.TSF) Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak {CFS} (CFS) 42.00 ft 0.862 4 2/09/01 2:00 0.588 7 1/05/02 16:00 1.06 2 2/27/03 7:00 0.505 8 8/26/04 2:00 0.639 6 10/28/0416:00 0.902 3 1/18/06 16:00 0.836 5 11/24/06 3:00 1.87 1 1/09/08 6:00 2.00 0.500 Computed Peaks Detention Facility Data: Type of Facility: Detention Pond -----Flow Frequency Analysis------- -- Peaks-- Rank Return Prob (CFS) 42.00 ft Period 1.87 1 100.00 0.990 1.06 2 25.00 0.960 0.902 3 10.00 0.900 0.862 4 5.00 0.800 0.836 5 3.00 0.667 0.639 6 2.00 0.500 0.588 7 1.30 0.231 0.505 8 1.10 0,091 1,60 50.00 0.980 Side Slope: ............................... 3.00 H:1V Pond Bottom Length: .............. 42.00 ft Pond Bottom Width: ............... 42.00 ft Pond Bottom Area: .................. 1764. sq, ft Top Area at 1 ft. FB: ................. 7056, sq. ft Effective Storage Depth:.......... 6.00 ft Stage 0 Elevation: .................... 0.00 ft Storage Volume: ..................... . 22248. cu. ft Riser Head: ................... .......... 6.00 ft Riser Diameter: ........................ 18.00 inches Number of orifices: .................. 2 Full Mead Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.75 0.203 2 4.25 2.88 0.297 6.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac -ft) (cfs) (cfs) (sq. ft) 0,00 0.00 0. 0.000 0,000 0.00 1764. 0.02 0.02 35. 0.001 0.011 0.00 1774, 0.04 0.04 71. 0.002 0.016 0.00 1784, 0.05 0.05 89. 0.002 0.019 0.00 1789, 0.07 0.07 125. 0.003 0.022 0.00 1799. 0.09 0.09 161. 0.004 0.025 0.00 1810. 0.11 0.11 197. 0.005 0.027 OM 1820. 0.13 0.13 234. 0.005 0.030 0,00 1830- 0.15 0.15 270. 0.006 0.032 0,00 1840- 0.25 0.25 457. 0.010 0.041 0.00 1892. 0.35 0.35 649. 0.015 0.049 OM 1945. 0.45 0.45 846. 0.019 0.055 0.00 1998. 055 0.55 1048. 0.024 0.061 0.00 2052. 0.65 0.65 1256 0.029 0.067 0.00 2107. 0.75 0.75 1470. 0.034 0.072 0,00 2162, 0.85 0.85 1689. 0.039 0.076 0.00 2218. 0.95 0.95 1914. 0.044 0.081 0.00 2275. 1.05 1.05 2144. 0.049 0.085 0.00 2333. 1.15 1.15 2380. 0.055 0.089 0.00 2391. 1.25 1.25 2622. 0.060 0.093 0.00 2450, 1.35 1.35 2870. 0.066 0.096 0.00 2510. 1.45 1.45 3124. 0.072 0.100 0.00 2570. 1.55 1.55 3384. 0.078 0.103 0.00 2632. 1.65 1.65 3651. 0.084 0.107 0.00 2694. 1.75 1.75 3923. 0.090 0.110 0.00 2756. 1.85 1.85 4202, 0.096 0.113 0.00 2820, 1.95 1.95 4487. 0.103 0.116 0.00 2884. 2.05 2.05 4779. 0.110 0.119 0.00 2948. 2.15 2.15 5077. 0.117 0.122 0,00 3014. 2.25 2.25 5381. 0.124 0.124 0.00 3080. 2.35 2.35 5693. 0.131 0.127 0.00 3147. 2.45 2.45 6011. 0.138 0.130 0.00 3215. 2.55 2.55 6336. 0.145 0.133 0.00 3283. 2.65 2.65 6668. 0.153 0.135 0.00 3352. 2.75 2.75 7006. 0.161 0.138 0.00 3422. 2.85 2.85 7352. 0.169 0.140 0.00 3493, 2.95 2.95 7705. 0.177 0.143 OM 3564, 3.05 3.05 8065. 0.185 0.145 0,00 3636. 3.15 3.15 8432. 0.194 0.147 0.00 3709. 3.25 3.25 8807. 0,202 0.150 0.00 3782- 3.35 3.35 9189. 0.211 0.152 0.00 3856. 3.45 3.45 9578. 0.220 0.154 0.00 3931. 3.55 3.55 9975. 0.229 0.156 0.00 4007. 3.65 3.65 10379. 0.238 0.159 0.00 4083. 3.75 3.75 10792. 0.248 0.161 0.00 4160. 3.85 3.85 11211. 0.257 0.163 0.00 4238. 3.95 3.95 11639. 0.267 0.165 0.00 4316. 4.05 4.05 12075. 0.277 0.167 0.00 4396, 4.15 4.15 12518. 0.287 0.169 0.00 4476. 4.25 4.25 12970. 0.298 0.171 0.00 4556, 4.28 4.28 13107. 0.301 0.174 0.00 4581. 4.31 4.31 13245. 0.304 0.181 0.00 4605, 4.34 4.34 13383. 0.307 0.192 0.00 4629. 4.37 4.37 13523. 0.310 0.207 0.00 4654. 4.40 4.40 13663. 0.314 0.225 0.00 4679. 4.43 4.43 13803. 0.317 0.248 0,00 4703. 4.46 4.46 13945_ 0.320 0.274 0.00 4728. 4.49 4.49 14087. 0.323 0.286 0.00 4753. 4.52 4.52 14230. 0.327 0.293 0.00 4778. 4.62 4.62 14712. 0.338 0.315 0.00 4861. 4.72 4.72 15202_ 0.349 0.334 0.00 4945. 4.82 4.82 15701. 0.360 0.352 0.00 5030. 4.92 4.92 16208. 0.372 0.368 0.00 5115. 5.02 5.02 16724_ 0.384 1.61 CFS at 8:00 on Jan 9 in Year 8 0.383 0.00 5201. 5.12 5.12 17248. 0.396 0.397 0.00 5288. 5.22 5.22 17782. 0.408 0.411 0.00 5376. 5.32 5.32 18324. 0.421 0.423 0.00 5464. 5.42 5.42 18874. 0.433 0.436 0.00 5553- 5.52 5.52 19434. 0.446 0.448 0.00 5643. 5.62 5.62 20003. 0.459 0.459 0.00 5734. 5.72 5.72 20581_ 0.472 0.470 0,00 5825. 5.82 5.82 21168. 0.486 0.481 0.00 5917. 5.92 5.92 21764, 0.500 0.492 0.00 6009, 6.00 6.00 22248, 0.511 0.500 0.00 6084, 6.10 6.10 22861. 0.525 0.972 0.00 6178. 6.20 6.20 23484. 0.539 1.830 0.00 6273. 6.30 6.30 24116. 0.554 2.930 0.00 6368. 6.40 6.40 24757. 0.568 4.230 0.00 6464. 6.50 6.50 25409, 0.583 5.710 0.00 6561. 6.60 6.60 26069, 0.598 7.150 0.00 6659. 6.70 6.70 26740, 0.614 7.690 0.00 6757. 6.80 6.80 27421. 0.629 8.190 0.00 6856. 6.90 6.90 28111. 0.645 8.660 0.00 6956. 7.00 7.00 28812. 0.661 9.100 0.00 7056. 7.10 7.10 29523. 0.678 9.520 0.00 7157. 7.20 7.20 30243. 0.694 9.930 0.00 7259. 7.30 7.30 30974. 0.711 10.320 0,00 7362. 7.40 7,40 31716, 0.728 10.690 0.00 7465. 7.50 7.50 32468. 0.745 11.050 0.00 7569. 7.60 7,60 33230. 0.763 11.400 0.00 7674, 7.70 7.70 34002. 0.781 11.740 0.00 7779. 7.80 7.80 34786. 0J99 12.070 0.00 7885, 7.90 7.90 35579. 0.817 12.390 0.00 7992. 8.00 8.00 36384. 0.835 12.700 0.00 8100. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu -Ft) (Ac -Ft) 1 1.87 1.31 1.61 6.17 6.17 23322. 0.535 2 1.06 ******" 0.42 5.28 5.28 18115. 0.416 3 0.84 ******* 0.47 5.74 5.74 20721. 0.476 4 0.90 ******* 0.46 5.58 5.58 19799. 0.455 5 0.86 ******* 0.64 6.03 6.03 22424. 0.515 6 0.51 ******* 0.28 4.47 4.47 13978. 0.321 7 0.59 ******* 0.15 3.32 3.32 9074_ 0.208 8 0.51 ******* 0.11 1,71 1.71 3820. 0.088 Route Time Series through Facility Inflow Time Series File: ................... dev.tsf Outflow Time Series File: ............... rdout Inflow/Outflow Analysis: Peak Inflow Discharge: ................... 1.87 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: ................ 1.61 CFS at 8:00 on Jan 9 in Year 8 Peak Reservoir Stage: ..................... 6.17 Ft Peak Reservoir Elev:....................... 6.17 Ft Peak Reservoir Storage: .. .......... -... 23322. Cu -Ft Flow Duration from Time Series File: ............ rdout.tsf New %Change Cutoff Count Frequency CDF Exceedence_Probability 0.48E-02 0.33E-02 CF5 0.248 % % % 0.290 0.19E-02 0.009 44884 73.196 73.196 26.804 0.268E+00 0.027 5969 9.734 82.931 17.069 0.171E+00 0-045 3327 5.426 88.356 11.644 0.116E+00 0.063 2271 3.704 92.060 7.940 0.794E-01 0.081 1597 2.604 94.664 5.336 0.534E-01 0.098 1079 1.760 96.424 3.576 0.358E-01 0.116 724 1.181 97.604 2.396 0.240E-01 0.134 517 0.843 98.447 1.553 0.155E-01 0.152 388 0.633 99.080 0.920 0.920E-02 0.170 271 0,442 99.522 0.478 0.478E-02 0.188 68 0.111 99.633 0.357 0.367E-02 0.206 24 0.039 99.672 0.328 0.328E-02 0.223 25 0.041 99.713 0.287 0.287E-02 0.241 14 0.023 99.736 0.264 0.264E-02 0.259 11 0-018 99.754 0.246 0.246E-02 0.277 9 0.015 99.768 0.232 0.232E-02 0.295 17 0.028 99.796 0.204 0.204E-02 0.313 17 0.028 99.824 0.176 0.176E-02 0.331 18 0.029 99.853 0.147 0.147E-02 0.349 11 0.018 99.871 0.129 0.129E-02 0.366 6 0.010 99.881 0.119 0.119E-02 0.384 11 0.018 99-899 0.101 0.101E-02 0.402 12 0.020 99.918 0.082 0.815E-03 0.420 12 0.020 99.938 0.062 0.620E-03 0.438 9 0.015 99.953 0.047 0.473E-03 0.456 10 0.016 99.969 0.031 0.310E-03 0.474 10 0.016 99.985 0.015 0.147E-03 0.491 3 0.005 99.990 0.010 0.978E-04 0.509 2 0.003 99.993 0.007 0.652E-04 0.527 1 0.002 99.995 0.005 0.489E-04 0.545 0 0.000 99.995 0.005 0.489E-04 0.563 0 0.000 99.995 0-005 0.489E-04 0.581 1 0.002 99.997 0.003 0.326E-04 0.599 0 0.000 99.997 0.003 0.326E-04 0.617 1 0.002 99.998 0.002 0.163E-04 0.634 0 0.000 99.998 0.002 0.163E-04 Duration Comparison Anaylsis: Base File: predev.tsf New File: rdout-tsf Cutoff Units: Discharge in CF5 Check of Tolerance Probability ---------Fraction of Time --------- Cutoff Base New %Change 0.164 f 0.68E-02 0.64E-02 -6.7 0.206 j 0.48E-02 0.33E-02 -32.7 0.248 0.31E-02 0-26E-02 -16.4 0.290 0.19E-02 0-22E-02 15.5 Check of Tolerance Probability Base New %Change 0.68E-02 0.164 0.162 -1.2 0.48E-02 0.206 0.170 -17.6 0.31E-02 0.248 0.213 -14.0 0.19E-02 0.290 0.304 5.0 0.332 0.13E-02 0.15E-02 16.9 0.13E-02 0.332 0,353 6.3 0.374E 0-85E-03 0.11E-02 30.8 0.85E-03 0.374 0.401 7.3 0.416 0.64E-03 0.70E-03 10.3 0.64E-03 0.416 0.419 0.8 0.458 0.36E-03 0.29E-03 -18.2 0.36E-03 0.458 0.451 -1.6 0.500 0.21E-03 0.82E-04 -61.5 0.21E-03 0.500 0.468 -6,4 0.542 0,15E-03 0.49E-04 -66.7 i 0.15E-03 0.542 0,480 -11.4 0.584 0.49E-04 0,33E-04 -33.3 0.49E-04 0.584 0.565 -3.1 0.626 033E-04 0.16E-04 -50.0 0.33E-04 0.626 0.605 -3.4 0.668 0.16E-04 0.00E+00 -100.0 0-16E-04 0.668 0-635 -4.9 0.710 0,16E-04 0.00E+00 -100.0 0.16E-04 0.710 0.635 -10.5 Maximum positive excursion = 0-033 cfs ( 9.6%) F <10% (OK) occurring at 0.342 cfs an the Base Data:predev.tsf and at 0.375 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.046 cfs (-21-0%) occurring at 0.219 cfs on the Base Data:predev.tsf and at 0.173 cfs on the New Data:rdout.tsf APPENDIX E Geotechnical Report Associated Fath Sciences, Ince DN E NJ W] 46 C6�W ra&n Over 25 Yearn a f'yer ce May 16, 2011 Project No, KE1 10083A Renton School District c/o Greene-Gasaway. PLLC P.O. Box 4158 Federal Way, Washington 98063 Attention: Mr. Sam Rosendahl Subject. Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report Nelsen Middle School Improvements 2403 Jones Avenue South Renton, Washington Dear Mr. Rosendahl: 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 tirne this report was written. We should be allowed to review the recommendations presented in this report and modify diem, if needed, once final project plans have been formulated. We [lave enjoyed working with you on this study and are confident that the recominexidations presented in this report will aid in the successful completion of your project. If you should have any questions regarding this report or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH ,SCIENCES, INC. Kirkland, Washington Kurt D. Merriman, P. E. Principal Engineer KDMlibf1d - KEI10083A3 - Projecis1201100831KDWP Kirkland 10 Everett N Tacoma 425 - 8 27-7701 425-259-0522 253-722-2992 www.aesgeo.com GeotechnicaCEngineering Water Resourees ` 7,zviron.merttaC.Assessjne?its and Remediation SustairtaGCe Developinent Services geologic -Assessments Associated Earth Sciences, Inc. Serving the Tactfic Worthwest Since 1-981 Subsurface Exploration, Geologic Hazards, and Preliminary Geotechnical Engineering Report NELSEN MIDDLE SCHOOL IMPROVEMENTS Renton, Washington Prepared for Renton School District clo Greene-Oasaway, PLLC Project No. KE110083A May 16, 2011 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS, ANY PRELIMINARY GEOTECHNICAL ENGINEERING REPORT NELSEN MIDDLE SCHOOL IMPROVEVIEN'TS Renton, Washington Prepared for: Renton School District c/o Greene-Gasaway, PLLC P.O. Box 4158 Federal Way, Washington 98063 Prepared by: Associated Earth Sciences, Inc. 911 5"' Avenue, Suite 100 Kirkland, Washington 98033 425-827-7701 Fax; 4.25-827-5424 May 16, 2011 Project No. KE110083A , 1id-.k1il�?ce F):piuj...ion ('e�x 'ic HOZ,7? ds, and �'815C77'V�Iida"'t, s(li0oi 11T 7;pVP112E'I:CC pl'�2i7?:L7121�' cCal Report Renton. ih%;shu;P!o�� Prolec; and Srie Conditiotls I. PROJECT AND SI'Z'E CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazards, and Preliminary geoteclaiical engineering studies for the proposed improvements at Nelsen Middle School. The location of the site is presented on the "Vicinity Map," Figure 1. The approximate locations of exploration borings cotnpleted for this study are shown on the "Site and Exploration Plan," Figure 2. Logs of the subsurface explorations completed for this study and copies of laboratory testing results are included in the Appendix. 1.) Purpose and Scope The purpose of this study was to provide geotechnical engineering recommendations to be utilized in the preliminary design of the project. This study included a review of selected available geologic literature, advancing 13 exploration borings, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow ground water. Grain size analysis and moisture content laboratory tests were completed on selected soil samples recovered from our exploration borings. Geotechnical engineering studies were completed to establish preliminary recommendations for the type of' suitable foundations and floors, allowable foundation soil bearing pressure, anticipated foundation and floor settlement, permeable and conventional pavement 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 Authorization to proceed with this study was granted by the Renton School District by means of Purchase Order #2011000115. Our work was completed in general accordance with our scope of work and cost proposal, dated March 21, 2011. This report has been prepared for the exclusive use of the Renton School District (RSD); 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 niade. Play 16, 2011 ASSOCIATED E4RTH SCIENCES, INC. .inL/fi�/1r!-KCJ10083f13-Prnlens1201100331KI:1WP Page i ,Subsu�face Explorntion, Geologic Hazards, and clsett Niiddie Schooi improvements Prelu�luu�r}� Georechnicri Engineering Report Renton, Wadi roe. PrOjecr rod Site Condirions ?.0 PROJECT AND SITE DESCRIPTION Project plans were under development at the time this report was prepared. Based on our discussions with Greene-Gasaway, PLLC, we understand that the project will consist of a substantial site renovation, with site improvements consisting of replacing some of the existing paving with permeable asphalt pavement, constructing two new baseball fields and one new soccer field; and installing a new storm water handling facility. We understand that infiltration is currently under consideration for the handling of storm water runoff. We anticipate that new structures and paving can be constructed close to existing grades, with typical cuts and fills of less than about 5 feet to achieve finished grade. Our previous work on the site included construction monitoring services in 1999 for building additions and new pavement areas to the north and west of the main building. Based on this previous work and our review of the published geologic map, we anticipated that the site is underlain by fill overlying glacially consolidated Vashon till deposits. The existing school includes a main building on the southeast part of the site, with athletic facilities to the north and west, and paved parking areas to the south, northeast, and west of the main building. Site topography is relatively flat to gently sloping, with sloped grassy "steps" which lead downward to the north and west to existing sports field areas. The ground surface continues steeply downward from the subject site, approximately 15 to 20 vertical feet to the north and roughly 25 vertical feet to the west, to nearby properties. A wooded stream corridor with areas of ponded water lies to the east. 3.0 SUBSURFACE EXPLOR-ATJON Our subsurface exploration completed for this project included advancing 13 exploration borings. The conclusions and recommendations presented in this report are based on the explorations completed for this study. Additional sources of geotechnical data are discussed in the `Subsurface Conditions" section of this report. The locations and depths of the explorations were completed within site and budget constraints. 3.1 Exploration Borings The exploration borings were completed by advancing hollow -stem auger tools with a track - mounted drill rig_ During the drilling process, samples were obtained at generally 2.5- to 5 - foot -depth intervals, The exploration borings were continuously observed and logged by a representative from our firm. The exploration logs presented in the Appendix are based on the field logs, drilling action, and inspection of the samples secured, Disturbed but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with American Society for Testing and Materials May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. 1PLNVH-KE110083113-P roleus1301J00831KLWP page 2 J'utrs�rrfnce Expinratiot2, Gev�ogic HrtZards, �u.a velserz ,brit(' School Improvemer�tc 1'relirrinary Geotechnical BnSuieerirag Report Re,yon, l w,,'!mAto17 Frolect and Site coadilions (ASTM) -D-1586. This test and sampling method consists of driving a standard 2 -inch outside - diameter, split -barrel sampler a distance of M inches into the soil with a 140 -pound hammer - free -falling a distance of 30 inches. The number of blows for each 6 -inch interval is recorded, and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or Now count. If a total of 50 is recorded within one 6 -inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N -value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring logs. . The sainples obtained from the split -barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing, as necessary, Ohservation Well Installation An observation well was placed in exploration boring EB -9 at the time of drilling to determine if a static ground water level was present and to measure its depth. On April 21, 2011, a static water level was measured at a depth of 33.81 feet. 3.2 Laboratory Tests Laboratory test results are included in the Appendix. The following laboratory tests were completed for this project: Three mechanical grain size analyses by ASTM: D-422 and D-1140 Two percent passing the No. 200 sieve by ASTM: D-1140 Five moisture content tests by ASTM:D-2216 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. We also reviewed field reports completed by Associated Earth Sciences, Inc. (AESI) during construction of an earlier renovation of Nelsen Middle School in 1999. Because of the nature of exploratory work below ground, extrapolation 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. May i6.. 2011 ASSOCIATED EARTH SCfENCES, INC. JP1.;rLlld - K6110083.19 - Pr0jrus110110083iKElWP Page .� Subsurface Exploration, Geologic Hazards, aid Neisen Middle School Inzproveznews Prelirrzirzary GeOICCIMical Digincering Report Rerzrort, YYnshin ion Project and. Site Conditions 4.1 Stratigraphy Fill Existing fill was encountered in all exploration borings except for EB -1, EB -2, and EB -5. The fill ranged in thickness from 4 to 31 feet within our explorations and consisted of loose to medium dense silty sand with gravel and scattered organics. Figure 2 shows the depth of fill encountered at each boring location. Existing fill is not suitable for structural' support. Existing fili should be removed from below planned structure areas, and should be recompacted Linder paving and athletic fields, especially if synthetic turf is planned. Existing fill is discussed in greater detail in the "Site Preparation" section of this report. Stratified Drift Sediments (undifferentiated) All of our explorations encountered medium dense to very dense brownish gray silty sand with gravel and sand lenses and beds, with thick sand beds encountered in exploration borings EB -5 and EB -9. As indicated above and described below, our previous work at the site and our review of the published geologic snap indicate that the site is expected to be underlain by glacially -consolidated soils, likely lodgement till; however, the sediments we observed were not typical of lodgement till sediments. The site sediments were somewhat more sorted and, in places, more stratified than typical lodgement till sediments, although that is the locally common sedimentary unit they most closely resemble. Lodgement till typically possesses high- strength and low -compressibility attributes that are favorable for support of foundations, floor slabs, and paving, with proper preparation. The site soils are silty and moisture -sensitive. In the presence of moisture contents above the optimum moisture content for compaction purposes, the site soils can be easily disturbed by vehicles and earthwork equipment. Careful management of moisture -sensitive soils, as recommended in this report, will be needed to reduce the potential for disturbance of wet native soils and costs associated with repairing disturbed soils. Weathered Teriiary Bedrock At the location of exploration boring EB -3, the stratified drift was underlain by a highly fractured silty sand with gravel, which appeared as "chips" in the sampler. We interpret this material to be representative of weathered Tertiary bedrock. Due to the relatively weak induration of the weathered rock, the description of the rock on the attached exploration log is similar to those used to describe soils. Where encountered, the weathered bedrock extended beyond the depth explored, Existing Geotechnical Data by AESI (1999) We reviewed several construction field reports for work completed on-site i31 1999. Our field reports addressed observation of bearing soils and compaction testing on shear wall foundations May 16, =011 ASSOCIATED EARTH SCIENCES, INC. JPC.fir,ire-KErraoa3A3-Page 4 Subsrllfitce Ezpinralion, Geologic Hazards, and Neisen Nfiddle sc.lwol Imp raveil ?ends Prelinrillaly Gc:uteelv2ice.:: E1lgltzeerirg Reno;? Renton, w01i Projecr and Sire col-Idilions within several classrooms. We also performed compaction testing on the subgf-ade for new parking areas. Soils described in these field reports are generally consistent with our current exploration borings. Published Geologic Map We reviewed a published geologic map of the area {Geologic Map of King Couv7ry, Washington, by Derek B. Booth, Kathy A. Troost, and Aaron P. Wisher; 2OO6). The referenced map indicates that the site vicinity is characterized primarily by lodgement till at the ground surface; with small exposures of Tertiary bedrock nearby. It is not unusual to find localized areas that vary from published regional scale geologic mapping, and that is the case with the stratified drift described at this site. We recommend that design activities for this project be based on subsurface materials observed in our on-site explorations 4.2 Hydrology Ground water seepage was encountered in a thick sand bed in exploration boring EB -9 at the tune of drilling, and we installed a plastic open -standpipe piezometer in EB -9 to allow measurement of ground water levels after drilling was completed. Observed ground water conditions are presented on exploration logs included in the Appendix. In addition, moist to wet soil was encountered at various depths within the existing fill, suggesting that perched ground water should be expected throughout the site. Perched ground water occurs where vertical infiltration of surface ';eater is impeded by lower -permeability soil units at depth. and water tends to move laterally above the perching layer. If construction takes place during the summer, we do not anticipate significant dewatering will be necessary. However, during the winter months, dewatering in the form of pumping and/or trenching may be necessary to collect seepage from excavations. Ground water conditions should be expected to vary due to changes in season, precipitation, on- and off-site land usage, and other factors. 4.3 Infiltration Potential/Permeable Pavement Considerations Our explorations encountered shallow materials that consisted of fill over stratified drift. The existing fill at ES -13, located at the proposed permeable pavement area at the west parking lot, classifies as sandy loam on the United States Department of Agriculture (USDA) textural soil triangle, Much of the underlying drift is silty, and the drift has been consolidated by glaciers, which limits its potential for use as an infiltration receptor. Wet soil, suggestive of perched ground water, was observed to vary in depth, but was often relatively shallow, which can also be a limiting factor that can be difficult or impossible to overcome. In the areas proposed for permeable pavement, adequate storage of infiltrating storm water will need to be incorporated into the pavement sections. We recommend that permeable pavement areas be provided with May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. IPLInAd - KE1111083A3 - Pro)wY12011008.31KEIWP Page 5 Subsurface Eaplortttion, Geologic Hazards, and Nelsen Middle School Improvetr�ertts Pre[intfnrrr}' Geolecrinical Engir:eerirzg Report Renton, Washirrgron Project and Sale Coad.;t omy either underdrains or a conventional surface water collection system to collect available water when rainfall exceeds the storage capacity and infiltration capacity of the permeable pavement system. lit general, we conclude that the potential for storm concentrated water disposal by means of infiltration is very limited at this site. As stated above, we installed a monitoring well extending below the fill and into a thick sand bed at the location of exploration boring EB -9, and measured ground water at 33.81 feet below the ground surface on April 21, 2011. Grain -size analyses performed on samples taken at 25 and 30 feet in EB -9 suggest that a suitable thickness of receptor soil for a deep discharge/injection well -type system inay exist above the observed ground water. Our borings did not verify the lateral extent of the potential storm water receptor, and such verification is an important component of the viability of the potential receptor. Steep slopes located to the north and west of the subject site, likely capped with a thick fill zone (as encountered in EB -8 an EB -9), also warrant additional study if a deep infiltration system is considered. Additional studies to support an infiltration design may also include additional explorations, consultation, or off-site ground water fate and transport studies, including at the residential property located at the bottom of the steep slope to the west of the subject site. May 16, 2011 ASSOCIATED EARTH SCIENCE'S, INC. JP1.11blld - HE 10083,13 - Projea.512011{N1831KEIWP Page 6 S'arlst�1�`aceb:xp10ratiol?, C=eologichazards, and IVe1'se1i Middle School lhzpravOa;evrts Preli�nlinon Georech,ucal Engmeering Report Rewon, Washugton Geologic llazards r,nd 'Viaga!ion", 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 ]united to slope stability, seismic, and erosion issues. It should be noted that the City of Renton Sensitive Areas mapping and the King County IMAP website show the site as lying within a known coal mine hazard area, with the Renton Sensitive Areas reap designating the coal mine hazard as "moderate." Based on the presence of existing development at and surrounding the subject site, we anticipate that the requirements for a detailed coal mine hazard study may be waived, per RMC. 4-3-050(D)(4)(b)(i)(c). We are available to provide a detailed coal mine hazard assessment for the project, if requested. 5.0 SLOPE HAZARDS AND MITIGATIONS Existing slopes on the site are moderately inclined and do not lrave visual indications of instability or unusually intense erasion. The slopes leading downward to the west and north of the subject site are steep and, based on the exploration borings completed nearby, likely include loose to medium dense fill material. These off-site slopes appear to be greater than forty percent, placing them into the "high landslide hazard" category per RMC 4-3- 050(J)(I)(b)(iii). However, these slopes did not show sighs of instability at the tiane of our exploration. Therefore, in our opinion, the proposed improvements should not negatively impact the slopes or cause instability of these slopes provided that storm water from the proposed permeable pavement area is not allowed to discharge over the slope faces. Similarly, if conventional pavement is used, storm water should not be directed to the steep slope areas. If a detention pond is planned in the area of these slopes, it will likely be excavated in fill and will need to be lined to prevent leakage into the slope soils. 6.0 SEISMIC HAZARDS AND MITIGATIONS The following discussion is a ,general assessment of seismic hazards that is intended to be useful to the school district in terms of understanding seismic issues, and to the structural engineer for preliminary structural design. In our opinion, the site does not include areas that meet the City of Renton definition for Seismic Hazard areas. 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 May M, 20I1 .ASSOCIATED EARTH SCIENCES, INC. JPL M(f - KE110033A3 - Prrjero1201100831K£1WP page 7 Sutisursace Expbratior, Geologic HcaZnrds, acrd Nelsen Middle School Improl�ements Preliminary Geolechnical ElIgWeerbq Report Renton, Woshingg on Geofogic Nczards anct MitiRatialrs 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 4j ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 6.1 Surficial Groustd Rupture Generally, the largest earthquakes that have occurred in the Puget Sound area are sub -crustal events with epicenters ranging from 50 to 70 kilometers in depth. Earthquakes that are generated at such depths usually do not result in fault rupture at the ground surface. However current research indicates that surficial ground rupture is possible in the Seattle Fault Zone. The Seattle Fault Zone is an area of active research. Our current understanding of this fault zone is poor, and actively evolving. The site is located approximately 5 miles south of the currently mapped limits of the Seattle Fault Zone. Due to the fact that flit site lies outside of the currently understood limits of the Seattle Fault Zone, the risk of damage to the project as a result of surficial ground rupture is low, in our opinion. 6.2 Seismically Induced Landslides Existing slopes oil the site are moderately inclined and do not have visual indications of instability or unusually intense erosion. The slopes leading downward to the west and north of the subject site are steep and, based on the exploration borings completed nearby, likely include loose to medium dense fill material. However, these slopes did not show signs of instability at the time of our exploration. Considering the history of adequate slope stability performance on-site, and the fact that no new buildings are proposed as part of the project, the risk to the project from seismically induced landslides is low, in our opinion, Storm water should be collected and routed away from sloping areas. If a detention pond is planned in the area of these slopes, it will likely be excavated in fill and will need to be lined to prevent Ieakage into the slope soils. 6.3 Li uefaction 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-gTain 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 Mcry 16, 2011 ASSOCIATEL) EARTH SCIENCES, INC. `PL/rfilkr - KE1100831I9 - Projrcrs 130!l00331KEI wP Page 8 Sa?�slrrfoce Exploration, Geologic Ha;.,2rds, and Nelsen Middle School h�ihroventenfs Prelua2u�nly Geoiechl�icai Epmeer;; g Reperl Relaorz, JVCShi17 10+z Creo?agic Hazards nrzrr ,�lui gafions 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 low risk of liquefaction due to relatively high density and lack of an extensive shallow ground water table. No detailed liquefaction analysis was completed as part of this study, and none is warranted, in our opinion. 6.4 Ground Motion It is our opinion that any earthquake damage to the proposed structures, when founded on suitable bearing strata in accordance with the recommendations contained herein, will be caused by the intensity and acceleration associated with the event and not any of the above - discussed impacts. Structural design should follow 2009 IBC standards using Site Class "C" as defined in Table 1613.5.2. The 2009 IBC seisinic design parameters for short period (Ss) and I -second period (Si) spectral acceleration values were determined from the latitude and longitude of the project site using the United States Geological Survey. (USGS) National Seismic Hazard Mapping Project website (ht ://earth uake.us s. ov/hazma s/), These values are based on Site Class "B". Based on 2002 data, the USGS website interpolated ground motions at the project site to be I.399g and 0.6328 for building periods of 0.2 and 1.0 seconds, respectively, with a 2 percent chance of exceedance in 50 years. These values correspond to site coefficients Fa — 1.00 and F, = 1.322, and a peak ground acceleration of 0.373g. The R,, FV, and peak horizontal acceleration values have been corrected for Site Class "C" in accordance with the IBC. 7.0 EROSION HAZARDS AND MITIGATIONS The following discussion addresses Washington State Department of Ecology (Ecology) erosion control regulations that will be applicable to the project. The subject site does not lie within an erosion hazard area as mapped in the City of Renton `Erosion Hazards" map. Also, the site soils are characterized by the Natural Resource Conservation Service as having slight erosion potential, This characterization translates to a "Low Erosion Hazard" designation by the City of Renton Municipal Code. However, the site is underlain by silty fill and drift sediments. Therefore, the erosion potential of the site soils is high, especially within the sloping areas of the site. As of October 1, 2008, the Ecology Construction Storm Water General Permit (also known as the National Pollutant Discharge Elimination System fNPDES] permit) requires weekly Temporary Erosion and Sedimentation Control (TESL) inspections and turbidity monitoring for all sites 1 or more acres in size that discharge storm water to surface waters of the state. Because we anticipate that the proposed project (field improvements) will require disturbance of more than 1 acre, we anticipate that these inspection and reporting requirements will be May M, 2011 ASSOCIATED EARTH SCIENCES, INC. YR, (b6r/ - ICF.110055 — ProjecW20J100831KDWP Page 9 Saahs1.11fcce FaJPiormion, Geologic Hazards, and rVelsert Aliddie School Improvemmrs Preliminary Geolechnical Eqmieenng Report RE7Zt0r2, YVashingtoli Geologic Hazards and Muigations triggered. The following recommendations are related to general erosion potential and mitigation. The TESL 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 trust 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 lowers 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 Pert -nit conditions. The general permit template is available on the internet', 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. 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 platnting and contractor implementation and maintenance. The most effective erosion control measure is the maintenance of adequate ground cover. Maintaining cover measures atop disturbed ground provides the greatest reduction to the potential generation of turbid runoff and sediment transport. During the local wet season (October I" through March 31"), exposed soil should not retrain 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 geed 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 1 littp://www.ecy.wl.goviprogrants/wq/stormwater/construction/constrtsctionfiDatpel-nlit pd{ May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. JPUOIN - M 10033,13 - Pro%erWr 6110083rKEI w Page 10 Szubszufvce Exploraoorz, Ocologic Hc,�zrrrls, arm RWelserr CSh .School Ira2Urrrverr:ents Prelirnunar.y Geoted,njc a1 Enoomeering Deport Renton, 1Lr7slarr�y°ri Geologic Hazards and M RgCZ2ons darns installed to reduce the flow velocity of the runoff and reduce the erosion potential within 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. With respect to water quality, having ground cover prior to rain events is one of the most important and effective means to maintain water quality. Once very fine sediment is suspended in water, the settling times of the smallest particles are on the order of weeks and months. Therefore, the typical retention times of sediment traps or ponds will not reduce the turbidity of highly turbid site runoff to the benchmark turbidity of 25 NTU. Reduction of turbidity from a construction site is almost entirely a function of cover measures and drainage control that have been implemented prior to rain events_ Temporary sediment traps and ponds are necessary to control the release rate of the runoff and to provide a catchment for sand -sized and larger sail particles, but are very ineffective at reducing the turbidity of the runoff. Silt fencing should be utilized as buffer protection and not as a flow -control measure. Silt fencing is meant to 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 flow control in front of the silt fence. A swalelberm combination should be constructed to provide flow control rather than let the runoff build up behind the silt fence and utilize the silt fence as the flow -control measure. Runoff flowing in front of a silt fence will cause additional erosion and usually will cause a failure of the silt fence. Improperly installed silt fencing has the potential to cause a much larger erosion hazard than if the silt fence was not installed at all. The use of silt fencing should be limited to protect sensitive areas, and swales should be used to provide flow control. 7.1 Erosion Hazard. Mitigation To mitigate the erosion hazards and potential for off-site sediment transport, we 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. It is easier to keep the soil on the ground than to remove it from storm water. The owner and the design team should include adequate ground -cover measures, access roads, and staging areas in the project bid to give the selected contractor a workable site. The selected contractor needs to be prepared to implement and maintain the required measures to reduce the amount of exposed May 26, 2011 ASSOCIATED EARTH SCIENCES, INC. JPLl,blyd - KE110083A3 - Projerr1110110083IKEIWP Page 11 Srr6stuf zce Exploration, Geologic. Hazards, and Nelsen ;Middle Schonl Improvements Prelinunar Georechmical Engineering Report Renton, Wshir71017 Geolo is Hazards and Mitig(7tIOIM ground. 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 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. It 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. ?. 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 15` and March 315`, these measures are required. &. nn -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 treasures should be adjusted and maintained, as necessary, for the duration of project construction. May 16, 2011 ASSOCIATED EARTH SCIEIV CIES, INC. JY11ehJI0 — KE)10083A3 - PmjeCGI20110083WLI WP Page 12 Subsurface Exploration, Geoiogic Hazards, and NOseli Middle Schoai improveltenr3 Prefiminary Geolechlucal Engineering Report Renron, Washm ton Geologic Hazards and Mif1'M1iol2s 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 controf ir3spector, the potential adverse impacts from erosion hazards ori the project may be mitigated. May 16, 2011 ASSOCIATED EARTH SCIENCES. INC. IPI./rhllrl - Kf11008M3 - Frojecu430110083i?;E1Wp Page 1 Sllhst11,ace Exploratiorz, GCoiogic Ha,yauds, 0,nd ,Velsen Middle school 1171provenzews Prebmiliary Geotechnical Engu�eerirzg Report Renion, 1-Yavl mi io>> Preliminary Design Recommendatims III. PRELIMINARY DESIGN RECOMMENDATIONS 8.0 INTRODUCTION Our exploration indicates that, from a geotechnical standpoint, the proposed project is feasible provided the recommendations contained herein are properly followed. The existing fill soils are adequate for pavement and new athletic field subgrade support, provided they can be recompacted to a firm, non -yielding condition and are not highly organic, Existing fill is not suitable for support of new foundations, structural fill or native glacial deposits are suitable for support of shallow foundations with proper preparation. The bearing stratum for structures is highly variable. We should be allowed to review project plans as they develop to provide case- by-case recommendations for foundation support of new structures, as needed. The site soils are generally not conducive to infiltration of storm water, as storm water will tend to perch above the existing soils. If permeable pavement is still being considered for this project, adequate storage of infiltrating storm water will need to be incorporated into the pavement sections. In addition, provisions to collect and dispose of the storm water runoff in excess of the permeable pavement storage and infiltration capacity will be necessary. 9.0 SITE PREPARATION Site preparation of foundation, playfield, and pavement areas should include removal of all grass, trees, brush, asphalt, debris, and any other deleterious materials. Any depressions below planned final grades caused by demolition activities should be backfilled with structural fill, as discussed under the "Structural Fill" section. Fill within the existing areas to receive new pavement or athletic field fill may be left in place provided it is inorganic, and can be compacted to a firm, non -yielding condition. It should be understood that placing new fill over the existing fill may result in settlement of pavernent or structures planned for this site requiring periodic maintenance. If settlement -sensitive improvements, such as synthetic sports fields, concession stands, or bleachers are planned in areas of existing fill, we should be allowed to offer siniation-specific recommendations. In such situations, the District must make decisions to balance costs of removing existing fill versus risks of post -construction settlement. We are available to answer questions during the decision process. The actual observed in-place depths of fill at the exploration locations are presented on Figure 2 and the exploration lags in the Appendix. All soils disturbed by stripping and grubbing operations should be recompacted as described below for structural fill. Once excavation to subgrade elevation is complete, the resulting surface should be proof -rolled with a loaded dump truck or other suitable equipment or systematically probed with a 1/2 -inch -diameter steel probe under our observation. Any soft, loose, or yielding areas should May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. lPlhNIff - KEl1008343 - Proiccl,IWJ10Q831KEIWP Page 24 Absw-tiae Fxplorauon, Geologir. Hazards, and Veiscn .4liddle schnoi In?provemerl's Prelimirtaly Geolec111lic0i Engineering Report Ren?o_, 1icshua tvrl Preliminary Desgn Recommendations be excavated to expose suitable bearing soils. The subgrade should then be compacted to at least 90 percent of the modified Proctor maximum dry density, as determined by the ASTM -.D-1557 test procedure, and to a firm; non-vielding condition. Structural fill can then be placed to achieve desired grades; ",,here needed and approved. 9.1 Temporary 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, temporary unsupported cut slopes can be planned at IHAV (Horizontal: Vertical) or flatter in the glacial drift deposits and 1.5H: IV in existing fill soils provided they are not saturated. Permanent cut OF fill slopes should not be steeper than 2H: IV. Tliese slope angles are for areas where ground water seepage is not encountered, and assume that surface water is not allowed to flow across the temporary slope faces. If ground or surface water is present when the temporary excavation slopes are exposed, flatter slope angles will be required. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHAIOSHA regulations should be followed at all times. 9.2 Site Disturbance Most of the on-site soils contain substantial fine-grained material, which makes them moisture - sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade wit]) structural fill. 9.3 Anter Construction Due to the moderate to ]sigh M situ moisture content of most of the site soils as judged in the field and confirmed through laboratory testing, it will likely be necessary to dry some of the site soils during favorable dry weather conditions to allow reuse in structural fill applications. Reuse of excavated site soils in compacted structural fill applications is only acceptable if such reuse is explicitly allowed by project plans and specifications. If construction takes place in winter, drying is not expected to be feasible, and we anticipate that some of the glacial drift soils and existing fill will be unsuitable for structural fill applications. Even during dry weather, site soils excavated for installation of buried utilities might not be suitable for utility backfill under; paving or other structures. We recommend budgeting for backfill of buried utility trenches in structural areas with imported select structural fill. For summer construction, significant but unavoidable effort may be needed to scarify, aerate, and dry site soils that are above optimum moisture content to reduce moisture content prior to compaction in structural fill applications. Care should be taken to seal all earthwork areas during mass May 16, 2011 ASSOCIATED EARTH SCIENCES, INC JPL11f)11f - KE110083A.? - Projrcrs I?OIIDD8,34FCEI tiS'F Page 15 slu7swyf ce ExpIoratiorz, Geoiagic Hazards, artd Nelsen Middle School lnzproverrzelw Pr•elimi?wo, Geotechnical Engineering Report. Rewon, Washington Preliminary Desi r: Recommetdol orrs grading ai the end of each workday by grading all surfaces to drain and sealing them with a smooth -drum roller. Stockpiled soils that will be reused in structural fill applications should be covered whenever rain is possible. If winter construction is desired and approved by the City, the existing pavement or new crushed rock fill could be used to provide construction staging areas. The stripped subgrade for crushed rock staging areas should be observed by the geotechnical engineer and should then be covered with a geotextile fabric, such as Mirafi 50OX or equivalent. Once the fabric is placed; we recommend using a crushed rock fill layer at least 10 inches thick in areas where construction equipment will be used. 10.0 STRUCTURAL. FILL Structural fill may be necessary to establish desired grades in some areas of the site. All references to structural fill in this report refer to subgrade preparation, fill type, 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/engineering geologist, the upper 1.2 inches of exposed ground should be recompacted to 90 percent of ASTM.:D-1557. If the subgrade contains 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 ASTM:D-1557. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with 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 perimeter footings or roadway edges before sloping down at a maximum angle of 2H: IV. 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 at least 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 thaai approximately 5 percent (measured on the minus No. 4 sieve size) should be considered May �, zol I ASSOCIATED EARTH SCIENCES, INC. JPLIrbI1� - Kb110083�E3 - Projeccsl�011�o831KE�.Wp page 16 Sub stat -face Exploraticm, Geologic Hazard's, and 7�Jelsen .��i`i�ldle S'Choul fmnrov�=azents f'reli�alrndly CevtEcllr�ical E1i�tnecrillg Re�nr1 Hentall, lY'r sktn�rort Prefulzinary Design Reccmin tid mons moisture -sensitive. All of the soil types observed on-site are estimated and have been confirmed by laboratory testing to contain significantly snore than 5 percent fine-grained material. Use of moisture -sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. The on-site soils contain substantial amounts of silt and are considered highly moisture- and disturbance -sensitive when excavated and used as fill materials. At the time of our exploration program, soil moisture content tests indicated that most soils encountered were at moisture conditions very near or above optimum for structural fill use. We anticipate that most excavated soils will require aeration and drying prior to compaction in structural fill applications. Reuse of excavated site soils in structural fill applications is only acceptable if such reuse is specifically allowed by project plans and specifications. If till 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 Iimlted to 5 percent by weight when measured on the minus No. 4 sieve fraction and at least 25 percent retained on the No. 4 sieve. 11.0 FOUNDATIONS Spread footings may be used for structural support when founded directly on undisturbed glacial deposits or on structural fill placed above suitable native deposits, as previously discussed. We recommend that an allowable bearing pressure of 2,500 pounds per square foot {psf) be used for design }purposes, including both dead and live loads. An increase of one-third may be used for short-teriri wind or seismic loading. Higher foundation soil bearing pressures are possible for foundations supported entirely on undisturbed glacial drift deposits; however, we do not expect that higher bearing pressures will be needed. If higher foundation soil bearing pressures are needed, we should be allowed to offer situation -specific recommendations. 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 1H:1V 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-1.557. In addition, a I.5H:1V lime extending down from any tooting 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. May 1 f, 2011 ASSOCIATED EARTH SCIENCES, INC. )P1,MVJ1i - KE110083A3 - Projeas1201109831KEIWP Page 17 ' jjIbs'Of is Expioratirni, Geologic and Rrelse)7 Middie khool Improvenienis Prelilmll iy Geolechnical Engineering Repari Renran, wasliinglon 1'i elinzinary' Design Recommendaitons Anticipated settlement of footings founded as described above should be on the order of 3/ inch or less. However, disturbed soil not removed from footing excavations prior to footing placement could result 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 inay be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the "Drainage Considerations" section of this report. If new foundations are plazuied in areas of existing fill, we should be allowed to offer situation - specific recommendations. Solutions might include removing existing fill, constructing rock - filled trenches, limited overexcavation and replacement of existing fill, or other alternatives. 11.1 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 washed pea gravel, The drains should be constructed with sufficient gradient to allow gravity discharge away from the proposed structures. 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 structures to achieve surface drainage. 12.4 FLOOR SUPPORT Floor slabs can be supported ou suitable native sediinents, or on structural fill placed above suitable native sediments. Floor slabs should be cast atop a minizriurn of 4 inches of clean, washed, crushed rock (such as '/s -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, 13.0 FOUNDATION WALLS All backfill behind foundation walls or around foundation units should be placed as per our recorninendations 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 of 2H: IV should be designed using an equivalent fluid of 5.5 pcf for yielding conditions or 75 pcf for fully restrained May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. lrUlb/id - KEIi008.3M - ProjeasWi 100831KEIWP page 18 Subsurfr ce ExplarnUI?71, GeologiC HC,1Z x625, LWO lltelserz Middle School Improlvinents Prcunlncvr - Geolechnical l'ng2neerrrzg Repot? Renton, Wcshington Ptslirzlirzaly Desiglz Recarzltnendaliolzs 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 2049 IBC, retaining wall design should include a seisanic 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 8H and 12H 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 cn-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 or other structures supported above the walls. Thus, the compaction level is critical and most 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 wails. 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. 13.1 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 = 250 pcf 0 Coefficient of friction = 0.30 14.0 ATHLETIC FIELD CONSIDERATIONS We understand that athletic field improvements, consisting of two new baseball fields and a new soccer field, are currently proposed as part of tine new improvements project. Existing fill was encountered within the fields with the deepest fills occurring near the northwest corner of May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. YFLIfh id - 1;r11(H283AJ- Piojec1sV20!l00831tCElWP Page 19 Subsw- �:e F,xpl01010i, Geologic Hazards, and ;Nelsen Middle SC11001 Improve+nenls Prelimi?iary Geotechnical Engineer;ng Re1)ort Rcnto+., Wcslsil to+1 Prelimina+y Design Recommendaliolis the subject site. if this fill can be recompacted to a firm, non -yielding condition, it can be used to support the new surfacing. It is unknown at this time if the new surfacing will be natural or synthetic tuff. Synthetic turf and natural turf fields that incorporate underdrains are settlement -sensitive structures. Post -construction settlement may render portions of the subdrairn system ineffective, and may result in field surfaces with visible low spots. Such settlement effects are difficult and cosily to repair, particularly when synthetic turf is used. Considering the substantial depth of existing fill below some portions of the site, complete removal of existing fill is likely not an economically viable alternative. Construction of new settlement -sensitive fields above existing fill carries risks of post -construction settlement. We are available to discuss settlement risks and approaches to reduce those risks when project plans have been formulated. Possible approaches include partial removal and recompaction of existing fill, or selecting athletic field design approaches that are less settlement-selasitive and easier to re - level. 34.1 Subsurface Drains (underdrains If athletic field underdrains are planned, the new underdrain system should consist of perforated PVC pipes, a minimum of 4 inches in diameter, placed approximately 15 to 20 feet apart. At this site, it might be appropriate to use steeper gradients than normal or underdrain system pipes to allow them to maintain flow if higher than normal past -construction settlement occurs. The pipes should have an invert of at least t2 inches below grade and be fully enveloped in at least 6 inches of free -draining material, containing less than 3 percent fines. The diameter of the drainage material should be larger than the size of the perforations in the drainpipe. The remainder of the drainage trench backfill should consist of free -draining material, conforming to the 2002 Washington State Department of Transportation (WSDOT) Standard Specifications for Road, Bridge and Municipal Construction, Section 9-03.12(4) "Gravel Backfill for Drains," which freely communicates with the field surfacing. We defer to the athletic field designer for specification of the new fields' surfacing material. 14.2 Subsurface Drain Trenchin Construction of the subsurface drains will require trenching into the underlying sediments. As part of this study, borings were advanced within the athletic fields to provide preliminary information on sediment density and ease of trenching. The fill soils within the athletic fields are in a loose to medium dense condition and should therefore be backhoe -excavated with limited difficulty. The underlying natural sediments consist of glacial drift soils, which are in a dense to very dense condition. The drift will be more difficult to excavate than the overlying fill soils, particularly where gravels and cobbles are present. Therefore, the contractor should be prepared to encounter dense to very dense sediments during the construction of the subsurface drains, and suitable excavation equipment should be utilized to expedite construction. May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. JP1,101 d - KE110083A3 - Proyeas1201J00831XE1HIP Page 20 ' uhs"a'xpf;e face lorn'ioll, oiogic 11017ards, and Nelsen Middle school h2mroveme�ts A-eiimincr v Geotechrncoi Engineering Repent Renton, Lv hir, tor. Preliminary Design Recom vl dations 14.3 1-10ht Pole Foundations We are unaware at this point if new field lighting will be constructed as pari of the field improvements. We offer the following recommendations to be used if new light poles are plaimed. Compressive Capaciries We recommend that drilled pier(s) be used for light pole foundations. Where feasible, the piers should penetrate at Ieast 5 feet into very dense glacial drift soils. For vertical compressive soil bearing values, we recommend using a unit end -bearing capacity of 5 tons per square foot (tsf) for glacially consolidated sediments. If light poles must be constructed in areas of existing fill deeper than light pole foundations, end bearing should be neglected in the structural design. The allowable end -bearing capacity includes a safety factor of 2.0 or more. Frictional Resistance For frictional resistance along the shaft of the drilled pier, acting both in compression and in uplift, allowable skin friction values of 1,000 psf in glacially consolidated sediments, and 250 psf in fill soils are recommended. It is also recommended that frictional resistance be neglected in the uppermost 2 feet below the ground surface. The allowable skin friction value includes a safety factor of at least 2.0. Lareral Capacities For design against lateral forces on the drilled pier, two methods are typically used. The parameter used to select the most appropriate design inethod is the length to pier stiffness factor ratio LIT, where "L" is the pier length in inches and "T" is the relative stiffness factor. The relative stiffness factor for the pier (T) should be computed by: T - El n t, where: E = modulus of elasticity (pounds per square inch [psi]) 1 = moment of inertia (in') ni, — constant of horizontal subgrade reaction (pounds per cubic inch [pct']) The factors "E" and "I" are governed by the internal material strength characteristics of the pier. Representative values of "n," for the soil observed on this site are presented subsequently. Piers with a LJT ratio of less than 3 may be assumed to be relatively rigid and act as a pole. The passive pressure approach may be used for this condition. For piers with a May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. JPL1Iblld - KENOTTA3 - Projecr0201100831KEiWP Page 21 Subsurface Expiorairioi7, Geologic Ha2tr-ds, nad Nelsen Middle School hnprovenmrits Preliminary Geolechmml 2 aymeer;ng Report Renton, Washilitort Preiiminmy Design Recommendations L/T ratio greater than 3, the modulus of subgrade reaction method is typically used, Both of these methods are discussed below. Modulus of Sub rade Reaction Method Using this method, the pier is designed to resist lateral loads based on acceptable lateral deflection limits. For granular soils, the coefficient of horizontal subgrade reaction is considered to increase linearly with depth along the pier. The expression for the soil modulus "K,," is Kf, = (ni)(XB), where "n," is the coefficient of modulus variation, "X" is the depth below the ground surface, and "B" is the pier diameter. We recommend using the value for the coefficient of modulus variation (m) of 150 pci for very dense glacial soils and 30 pci for existing fill soils. Passive Pressure Method Lateral loads on the shallow foundation caused by seismic or transient loading conditions may be resisted by passive soil pressure against the side of the foundation An allowable passive earth pressure of 350 pounds per cubic foot (pcf), expressed as an equivalent fluid unit weight, may be used for that portion of the foundation embedded within dense to very dense native drift. Below a depth of 2 feet in existing loose to medium dense fill soils, an allowable passive earth pressure of 200 pcf should be used. The above value only applies to foundation elements cast "neat" against undisturbed soil. For new structural fill placed around the pier shaft, a passive earth pressure value of 250 pcf is reco;nmended. All fill must be placed as structural fill and compacted to at least 95 percent of ASTM:D-1557. Passive resistance within the upper 2 feet should be ignored. However, passive values presented are used assuming an equivalent triangular fluid pressure distribution over 2 pier diameters beginning at die surface and held at a constant depth greater than 8 feet. The triangular pressure distribution is truncated above 2 feet. The presence of large -diameter boulders below the proposed light pole locations is possible. The owner should be prepared to move the light pole locations if boulders are encountered. Some drilling contractors can employ specialized drilling equipment to drill through large boulders, but these methods are often very time consuming and/or expensive. 15.0 PAVEMENT RECOMMENDATIONS We understand that permeable pavement is being considered for the parking area to the west of the existing building, and that new conventional pavement may also be included with the proposed improvements. We have presented recommendations for new conventional pavement and porous pavement in the sections that follow. May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. 1PLlrblid - KEI)0033113 - Projects l201100831KEVWP Page 22 5a�i�s �t«ce &rplorct?cin, Geologic Hazoz ds, and Nelsen iwiddle Sc,+ool Improvements Preiuumary Georecllnical Engineering Report Ren.orz, WaNhirift01. helunuzmr Design Rec:or moidatioris 15.1 New Conventional Pavement Conventional pavement for this project would be supported by very dense silty sand (drift), new structural fill, or recompacted existing fill. These soils should be suitable, with proper preparation, to allow the use of standard paving sections. Because some of the site soils were substantially above optimum moisture content at the time of our exploration program, remedial subgrade preparation might be required below the paving, particularly in areas of existing fill and silty weathered drift soils. Remedial preparation measures could include removal of some of the existing site soils below the planned pavement section and restoring the planned subgrade elevation with select imported structural fill, or aeration and drying of existing soils prior to compaction of the road subgrades_ It may be necessary to use a separation fabric between the existing subgrade and new structural fill if fine-grained sediments are exposed during grading. Preparation of pavement subgrade areas should follow the recommendations of the "Site Preparation" and "Structural FiLl" sections of this report. The proposed subgrade, whether it is cut native soils or compacted structural fill, should have a minimum density of 95 percent based on the ASTM:D-1557 test procedure within the upper foot below the pavement section. Subsequent to compaction or recompaction, the subgrade should be proof -rolled with a loaded dump truck. Any deflecting areas or soft spots detected during proof -rolling should be excavated and replaced with properly compacted structural fill. We recommend that the final determination of how to prepare the pavement subgrades be made at the tune of construction when weather and field conditions are known. Upon completion of any recompaction and proof -rolling, a conventional pavement section consisting of 21/2 inches of asphaltic concrete pavement (ACP) underlain by 4 inches of 11/4 -inch crushed surfacing base course is recommended for car parking areas. A heavier section consisting of 3 inches of ACP over 6 inches of crushed rock should be used in areas where bus traffic or other heavy vehicles are expected. The upper 1 inch of 11/4 -inch crushed rock can be replaced with I'/z inches of 5/8 -inch crushed rock as a leveling course, if desired. The crushed rock course must be compacted to at least 95 percent of the maximum density, 15.2 Porous Asphalt or Permeable Pavement Recommendations provided for use in planning and design of the porous pavement proposed as surfacing in the area of existing parking area west of the existing building focus on providing a uniform base for support of the porous pavement and allowing maximum infiltration within the soils beneath the pavement. Approximately 10 feet of fill was encountered over glacially consolidated drift in exploration boring E13-13 (Figure 2). The density of the fill within 18 inches of the existing parking lot surface is considered to be predominantly medium dense. In order to provide a uniform base for support of the porous pavement and to allow maximum infiltration within the soils beneath the pavement, our recommendations include scarification of the upper 12 inches of soil and all across the exposed parking subgrade. Moy 16, 20J ASSOCIATED EARTH SCIENCES, INC,A] IPL.Irbild - MJ6083A3 - Piojen51201100831KElWP Page 23 Subsu+face Exploration, Geologic Hazards, and Rfelseit rblidd?e 5ehool Intprovenzerus Preilminaiy Geolechnical E)igineering Report Rel�loyt, Li'aslurt [otz Prelzinu7 + ' Desi r2 Recommendations The surface of the parking lot should then be graded to drain at a gradient of no more than I percent toward the present surface water drainage system. Soil removal and surface grading should be done in such a way as to avoid densification of the exposed soil surface. Following subgradc preparation, we recommend a passenger car pavement section consisting of a 3 -inch compacted porous asphalt paving above a 3 -inch thickness of "choker course" consisting of '/B -inch crushed surfacing top course. Below the choker course, a 12- to 18 -inch - thick storage layer consisting of 2 -inch permeable ballast (WSDOT 9-03.9[2]) should be placed above the soil subgrade. The storage layer should be sized for an appropriate amount of storin water storage assuming a porosity of 0.30. Since a limited amount of the water will infiltrate the pavement subgrade during large storm events, a drainage system should be established on the downgradient side(s) of the permeable pavement. The drainage system should include perforated pipes connected to the site storm drain system. In areas where buses, garbage trucks, fire trucks, delivery trucks, or other heavy vehicles will be driven or parked, we recommend a paving section consisting of 6 inches of porous asphalt, 3 inches of choker course, and 18 inches of storage layer. Porous asphalt requires regular cleaning to avoid becoming clogged with silt and contaminants and to maintain the porous properties. We recommend the RSD establish a cleaning schedule as part of the long-term site maintenance. 16.0 DETENTION POND CONSIDERATIONS We understand that a detention pond is currently under consideration at the northwest portion of the subject site as part of the proposed improvements. As part of our exploration program, we completed three exploration borings at the area of the proposed northwestern detention pond. In summary, these exploration borings encountered loose to medium dense fill to depths ranging up to 31 feet, with the deeper fill encountered near to the top of the steep slope leading downward to the west of the subject site. Since fill sediments were encountered at the likely elevations of the pond bottom and side slopes, it is our opinion that the pond needs to be Provided with a liner. A synthetic liner is recommended over a soil liner for this project because future settlement in the underlying fill may lead to "cracking" and leaks in a soil liner, which may adversely impact the nearby steep slope. We have also included recommendations for the use of a cellular confinement system to retain the pond liner cover soil or topsoil growth medium above the liner, if required. Since the pond will be lined, the existing fill can remain in place, provided the material is cleaned of debris, moisture -conditioned, and compacted to a firm and unyielding condition. A cellular confinement system is recommended to retain liner cover soils and any recommended topsoil growth medium above the completed liner. A cellular confineinent system, such as Geoweb® or TerracellO, can be installed for purposes of topsoil containment and slope erosion control. The proposed system should be approved by the geotechnical May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. M,M)MY - ELI 1 0083A a - Projecfi l?01 f00631KE1wP Page 24 Subsurface Es�pioro0on, Gcoiogic Hazards, and Nelsen A� JXd School Inmrovements Prelinru�aiy Geoieclmir:ai Eltguieci Repo='1 Rentore, Washilr tole Preliminary Desmon Reconune;radars engineer prior to installation. We recommend the use of 6 -inch -deep cells, Instal] the selected system in accordance with the manufacturers recommendations. Anchors for the cellular confinement system should be installed so as to prevent stress points from forming and to prevent the system from sliding. Anchors should not penetrate the pond liner, The cell openings should be filled with either a clean pit run sand and gravel as a liner cover or topsoil specified by the project landscape architect, depending on location in the pond. interior detention pond slopes should be made at a maximum gradient of 3H: IV or flatter, and should be consistent with the manufacturer's recommendations for the cellular confinement system that is selected. Exterior perimeter berm slopes, if required, should be trade at a maximum gradient of 2H:1V. Perimeter pond berms should have a minimum top width of 6 feet. A base key equal to one-half the berm width and a minimum of 3 feet deep should extend below the base of the pond berm. Additionally, detention pond berm geometry should conform to municipal design standards. AESI is available to perforin a geotechnical review of the final detention pond plans once they are available. 17,0 PROJECT DESIGN AND CONSTRUCTION MONITORING At the time of this report, site plans, grading plans, structural plans, and construction methods have not been finalized. We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations for buildings and of new pavement 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 the current scope of work. If these services are desired, please let us know, and we will prepare a cost proposal. May 16, 2011 ASSOCIATED EARTH SCIENCES, INC. ;PLlrhHrl - KEI )0O83A3 - Projecr62011008PK€IWP Page 25 Si&swfoce Exploration, Geologic Hazards, chid Ne?Selt Middle School IrnPt-ai-ements Preiinninary Geotechnical Engineering Report Renton, Yi'ashin tori Preiuninary Desi n Reco.ruatendalior"s 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. Laub, L.G.: L.E.G. Prolect Engineering Geologist Attachments: Figure I: Vicinity Map Figure 2: Site and Exploration Plan Appendix: Exploration Logs Laboratory Test Results 15Un 1,� Kurt D. Merriman, P.E. Principal Engineer May 16, 2011 ASSOCIATED E,4RTH SCIENCES, INC. )PLAbbe! - HE IX3313 - Pr0lect5120110053WDWP Page 26 r I f +4 « � �� r✓a 4�i3 II V:'i - � ' 1✓ir � LrK x 4' {mss �qq PtMvo( i Irlr. _�l^p PlnnR` ���Q� ry�y F _ s• . S;4•M I r ' d1 �� '•"?�'3[Sa��ii4�i � r... IN ' -.r'( � " ��{, t r ^ ;"II �•l St3Akt��4 _ '''"ry'.+�ki.,}.. '�-.�'� � i - .. r 8•^.: f Yk [ I y. l ir Iu Tukupila xF {{ .-..,._ ...,_.. �, �--..........Ejj. I ir ■- xi S'• P 1 f y`k•� �f CA6IP, a J ' � I 3 J" - i� i 1µ t« r . � 1 9000 200 • `'e'er � .� �If r ;�_•._ �;: i� i v :� 4 N REFERENCE: USGS TOFO! FEET w Associated Earth Sciences, Inc. VICINITY MAP FIGURE 1 x, NE.LSEN MIDDLE SCHOL DATE 4111 - RENTON, WASHINGTON PROJ. NO. 14E9100B3A 55� WNW an. 2t7J REFERENCF':.KING COUNTY GIS n V ��sc�ci�ted �:a�t't� Sciences, iz$c. SdTE A1rf� EXPI�ORATiDN PIAN L FIGURE 2 j "'NELo�N (�9JDf)LE nAT� 5111 <, „��,,� . _ RENTON. 'vUASIIINGTON c PROj NO KE31ao$uA APPENDIX Classlfications of soils in this report are based on visual field and/or laboratory observations, which include densityiconsistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field or laboralory lasting unless presented herein. Visual -manual ariftr laboratory ciassibcafion methods of ASTM D-2487 and D-2488 were used as an identifrcalion guide for the Unified Soil Classification System. 0 r g Associated Earth Sciences, Inc. EXPLORATION LOG KEY FIGURE Al 0 lid 004_�" 0 0 a ° Well -graded gravel and Terms Describing Relative Density and Consistency — aN r� a_ravel with sand, little toi3ensil SPT12'blawslfoot v °ila0 o trD fides —� Very i_onse 6 Eo 4 > w ° ' a ° a ° °4°0° ° ° ° o ° Pocrly-graded gravel Corirse- Loose 410 10 i Grained Soils Medium Dense 10 to 30 �' U o`, w °o° °° GP and gravel with sand, Test Symbols 0 0 o v 6 o°ooa° oO°°o little lc no fines Dense 30 to 5G Very Dense >50 G =Grain Size N o z o°°°° PJB =Moisture Content ° u ° Silly gravel and silly Z T� ° Consistency SPTI?}blowsifoot A = Atterberg Limits o m ami 9 ° ° GM gravel with sand Very Soft to 2 C = Chemical Fine- o Y v° c e e Soft 2 to 4 DD = Dry Density Grained Soils C o m Medium SliH 4 tc 8 K= Permeability �' AC o Stift 8 to 15 y Clayey gravel and Very Stiff 15 to 30 7 NI GC clayey gravel with sand Hard >30 Component Definitions p C Weil -graded sand and 6 Descrip5ve Term Size Range and Sieve Number sW sand with gravel, little boulders Larger than 12" o LL C : _ to no fines Cobbles 3" to 12" Gravel 3" to No. 4 (4 75 mm) Poorly sand U S and sand with gravel, 9r Coarse Coarse Gravel 3" to 3f4" Fine Gravel 3/4" Io Nc. 4 (4.75 mm) m c o � o little 1D no fines Sand No. 4 (4.75 mrn) to No 200 (0.075 mm) Coarse Sand No. 4 (4.75 mm) to No. 10 (2.00 mm) m y � ° ro y Sf� 5iify sand and silty sand with Medium Sand NO. 10 (2.00 mm) to No 40 (0.425 mm) Fine Sand No. 40 (0.425 mm) to No 200 10.075 mm) v o d LL gravel Silt and Clay Smaller than Na. 200 (0 075 mm) U 7 sc Clayey sand and (3) Estimated Percentage Moisture Content @ m clayey sand will gravel Percentage by Dry -Absence of moisture, V) Component Wei ht dusty, dry to the touch grace c5 Slightly. Moist - Perceptible Silt, sandy silt, gravelly sill, ML sill With sand or gravel Few 51010 moisture Litt}e 15 to 25 Moist - Damp but no visible in t With Non -primary coarse water oy Clay of low to medium constituents 15% Very Mpisl - Water visible but z -o m CL plasticity; slaty, sandy, ar Fines content between not free draining ry Efrom gravelly clay, lean Clay 5% and 15% Wet 'Jisible free water, usually below water table -- _ Organic clay or sift of low N a UJz Symbols 2—_— GL plasticity lor 2 _ Sampler ampportion of 6" Cement grout 15 Type surface seal Elastic silt, clayey silt, silt Ali With miraCEDUS er 2-0'0D Sampler Tye s bescripfton Benlonile o diatomaceous fine sand or Split Spoon m cel seal co u silt Sampler 3.0" DD S hl S oan Sam ler p p p - _ ': Filter pack w 1h (SFS Clay of high plan#;City, .a � o 3.25" OD Split -Spoon Ring Sampler (.) := blank casing a ,n CH Sandy or grave clay, fat Bulk sample seclion 3.0° oi] Thin Wall tube Sampler =' Screened casing ,�-° E 15 D- clay with sand or aravel {including Shelby tube) or Hydrolip rIS p Grab Sample v ith filler pack c _cr Organic clay or silt of o Porion not recovered End cap OH medium to high r�if% pl25ticity Depth f Depth Iz} Percentage by dry weight (4) ground water of (SPT) Standard Penetration Test 4 At time of drilling D-1586) Peat, muck and other {ASTM t3) Q Static water leve; (date) m T C N o PT highly organic soils In General Accordance wilh Standard l far Description 151 Combined USCS symbols used #or O and Identification of Sails (ASTM D-2486) fines between 5% and 153 Classlfications of soils in this report are based on visual field and/or laboratory observations, which include densityiconsistency, moisture condition, grain size, and plasticity estimates and should not be construed to imply field or laboralory lasting unless presented herein. Visual -manual ariftr laboratory ciassibcafion methods of ASTM D-2487 and D-2488 were used as an identifrcalion guide for the Unified Soil Classification System. 0 r g Associated Earth Sciences, Inc. EXPLORATION LOG KEY FIGURE Al 0 lid 004_�" 0 0 a Associated Ea ti, Sciences, Ii1c. Log L--`` D -Exploration 17-,7 Projecl Number Exploration Number D Ll Sheet KE110083A EB-1 1 of 1 Project Name Ne,ISen Middle School Ground Surfa—c Elevation (ft} Renton WA Location Datum NZA --�� Boretec/TrK RI DrilierlFquipment Date Start/Finish 4!1All 1 4118111 140# / 0'. Hammer WeightlDrop Hale Diameter (in) r,, a S E U Q ° >. C — > J Blows/Fo140 T m 0c �E � o ❑` DESCRIPTION `� 10 20 30 Undifferentiated Stratified Drift S_t Moist, brownish gray, silty fine SAND, with gravel 37 r S-2 Moist, slightly rust-stained brownish gray, silly fine to medium SAND, with 38 gravel. 0+ E 115E " S-3 Moist. brownish gray, silly fine to medium SAND, with gravel and brown 32 sand pockets. I 41 541 " 10 S-4 Moist, brownish gray, silty tine to medium SAND, with gravel f 6 i j Bottom of exploral ion boring at 10 9 feet r I 15 i � i Ir 20 I E I 25 i E 0 N N a C Q Sampler Type (ST): r m 2" OD Split Spoon Sampler (SPT) No Recovery M - Moisture Logged by: m 3" Oil Split Spoon Sampler (D & M} U Ring Sample $Z Water Level (} Approved by: ,)PL ® Grab Sample Shelby Tube Sample l Water Level al time of drilling (ATD) Associated EaOl, Sciences; Inc, Ex 1oratlon Lo Project Number Exploration Number Sheet 4* l KL110083A E13-2 1 of 1 Project Name Nelsen Middle School Ground Surfane Elevation (fl) Location Renton, WA — _ Datum �! DrIler/Equipment Borelec/Track Riq�.__ Date Sart+Finish 4(18111 4LR11,.Lt Hammer WeighUDrop 1.40#! 30" Hole Diameter (in± E,^ vi U 2 j L Blows/Foot !j T DESCRIPTION 10 2c 30 40 Undifferentiated Stratified Drift i —�- 15 M S-5 I 20 25 Moist, silghtly rust -stained brownish gray, silty fine to meduurn SAND. with gravel Moisl, brownish gray, silty fine SAND, with gravel Moist same. Moist, brownish oray, silty fine to medium SAND, wiih gravel isl, brown, fine to medium SAN L), with gravel and trace sill. tom of exploration boring a1 16 6 feel, 5 11 23 15 33 $7, 123 I28 48 4 i ' N I 2 M Sampler Type (ST). o mm 2" dD Split Spoon Sampler (SPT) No Recovery M - Molsture Logged by: JPL m LL] 3" OD Split Spoon Samp}er (D & M) ® Ring Sample SZ Water Level {) Approved by: a ® Grab Sample Shelby Tube Sample Z Water Level at lime of drilling (ATD) G N Associated E. -IT -111 Sciences, Inc. I Exploration Lo E V- f Project Number Exploration Number + (`r� € 11110083A F-13-3 Project Name Nelsen Kdd#e School Local"ion Rnton. WA DrilierrEqulpment Boretec/Track Rig_ Hammer WeighflDrcp 140# / 30" Sheet 1o`1 Ground Surface Fleval an (ft) Datum NIA _ _ — Date Start/Finish A11 R, 11,4LIR!1 j Hole Diameter jr'j F^ m 2" GD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL m m 3" 017 Split Spoon Sampler (D & M) lu Ring Sample Q Water Leve! O Approved by: Grab Sample E SheEby Tube Samp)e 1 Water Level at time of drilling (ATD) L c E i-- — 0) Blows/Fc 5 T v7 cg c E o D DESCRIPTION " 3: 10 20 30 Fill rt 6 inches wet, brown. silly SAND, with gravel and organics eve{ moist, S -g bluish gray, silty SAND, with oravel g ! i i 8 Ali 9 - 5 I Moist, brownish gray and bluish gray, silty SAND, with gravel S-7 I I II A22 Mnisl, same 5-8 3 4 �a i 0 TIMoisl to wet brown and gray, silty SAND, with gravei and organics. S-9 3 3 6 3 i Undlffereretleted Stratified Dr -1h I i I 15 I i Moist, rust -stained gray, silty fine to medium SAND, with gravel S-10 5 9 A22 13 Weathered TertiaryBedrock 20 Moist, brownish gray, Silty fine SAND. with gravel. 5 1 p! BOVOM of exploration boring at 20 4 leel 25 gommnlor E 7—. fgTV m 2" GD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL m m 3" 017 Split Spoon Sampler (D & M) lu Ring Sample Q Water Leve! O Approved by: Grab Sample E SheEby Tube Samp)e 1 Water Level at time of drilling (ATD) Assorialed Earth Sciences, Inc Exploration Lo �LL , Project Number Exploralion Number I.J KE 110083A EB -4 i of 1 Project Name Nelsen Middle School Ground Surface Eievaiian (ft? Localior _Renton. VVA Daturn N/A. DrillerrEqu pment `Bor 3lec/Track Rig Date Star -)Finish 4/1 W-1 1 411 Rr'11 Hammer Weight)Drop 140# i 30" Hole Diameter (n) 6,- E ^ S -t S-3 20 25 1 E Q J Blows/Foot DESCRIPTION m 10 20 30 40 O Fill Moist, hiown, silky SAND, with gravel and organics Moist to wel, brown and gray, silty SAND, with gravel and organics Moisl, ruse -stained gra}, sil!v fine to medium SAND, with gravel. Undifferentiated Stratified brill Moist brownish gray, silty fine SAND, with oravei Moist, with rust staining, same. Bottom V exploralion boring at 15.5 feel 3 i i; i X13 EI I 3 '&� m Sampler Type (ST) 2" OD Split Spoon Sampler (SPT) 0 No Recovery M - Moisture Logged by: JPL o 3' OD Split Spoon Sampler {D g M) ❑ Ring Sample 4 Water Level (j Approved by: © Grab Sample Shelby Tube Sample 1 Water Level al time of drilling (ATD) N N Associaled Lartli Sciences, Inc. Exploration La a Project Number Exploration number �T Sheet f EKE -11008"A , EB -5I of 1 Project Name Nelsen Middle School Ground Surface Elevafion (tl) Lcrafion Renton, WA _ Datum NIA _ DrilierrEquipment Boretec/Track RIQ Date StarllFinish X11$119 d11 ft Hammer WeighUDrop 4p# / 30" �T Hole Diameter (in) 4° s m a S E T ° a� DESCRIPTION T ° u > o m Blows/ Foot to 20 3o ao Undifferentrated Stratified Drift Moist, slightly rust -stained, slity fine to medium SAND. with gravel. r S -f 1g� 26 53 27 I 5 I Moist, brownish gray. silty fine to medium SAND, with gravel and sand I � t S-2 lenses- 17 23 ®q 22 Moist, brownish gray, fine to rnediuM SAND, with gravel. S-3 9 15 1 A38 22i t Moist, same l ! S 4 its 28 58 31 i 15 I Moist, Same S 5 20 22 50 29I I � Bolfom of expioration baring at 16 5 feet i 2U I kI I i 25 I 2" 00 Split Spoon Sampler (SPT) E No Recovery M - Moislure logged by: JPL 3' OD Split Spoon Sampler (D & M) Ring Sample 52 Water Levei (j Approved by: ® Grab Sample Shelby Tube Sample I Water Level at time of drilling (ATD) Associalcd Ea th Scienceb, litr. Exploration Lo Projectm Number Expioratian Number Sheet --J� ' KE110t783A El 1 of i Project rNa-ne Nelsen Midd4e S0001 _ Ground Surface Eievation (ft) Lc,-aiion _Renton- VVA Datum Driler%Equipment Boretec/TrackRig __ DaleStart/Finish 4+1RII1 4118li Hammer weigt L'Drop 140# i 30" _ _ .� Hole Diameter (in) 6_ a a E a ' Blows/Foot o T n DESCRIPTION mi 10 20 30 40 --- Fill Moist to wet, rust -stained brown,, silty SAND, with gravel. 5 Moist to wet, same with woody debris. S-2 Wet, same i S-3 1U - -rMoist, rust -stained brownish gray, silly SAND, with gravel. S-4 15 rh S-5 26 S -e Moist to wet, brown and grav, silty SAND, wish gravel and organics. Moist, same 25Same for 6 inches. Undifferentiated Stratified Drift S-7 Moist, slightly rust -stained, silly fine to medium SAND, with gravel 0 $o4tDm of exploration boring at 26.5 feet N N � a K 7� 8 15 7 2C 31 A'21 A23 0 E Sampler Type (ST) - 2" DD Split Spoon Sampler (SPT) No Recovery M • Moisture Logged by: JPI_ o 3" OD Split Spoon Sampler (D 8 M) U Ring Sample I Water Level () Approved by: W © Grab Sample Z Shelby Tube Sample T- Water Level at time of drilling {ATD) a Associated Earth Sciences, Inc. Exploration Log –1 -,–_I Project Number Exploration Number I Sheet KE110083A � EB -7 f 1 of 1 Project Name Nelsen Middle School Ground Surface Flevation {ft} Location Renton, WA Datum N/A Dri ler/Equipment Boretec/Track Riq _ Date Start+Finish 411R/11 4118/11 Hammer WeightlDrap 140# ! 30" Hole Diameter (in)��— _ m _ ° G a 5 m rDm •� "3 Blows/Foot N S ? o T' DE=SCRIPTION n r Q � 10 20 30 40 Fill k E I � Moist, rust -stained brownish gray, silty fine to medium SAND, with gravel. 5f 3 B 12 tt3 I s 5 Moist to we,,, brown and gray, silty fine to medium SAND, with gravel and I S-2 organics. B ®14 fi S3 Moist to wet, same, i f5 B t l Undifferentiated Stratified Drift Moist, bluish gray, silly fine to medium SAND. I S-4 6 13 f 7 I i 5 Moist to wet, rust -stained bluish gray, fine to medium SAND, with silt and f I 8-5 trace gravel. 12 17 &.3 ,s i Botlom of exploration boring at 16 5 feel 20 i 25 I JP]Onpn l i yNe to 1). m 2" OD Split Spoon Sampler (SPT) No Recovery M - Moisture Logged by: JPL 3" OD Split Spoon Sampler (D & M) Ring Sample 7- Water Level O Approved by: ® .arab Sample � Shelby Tube Sample i Water Level at time of drilling (ATD) Associated Earth 5cienus, lnc. Exploration Log f� m r Projecl Nuber ExplDmiion Numbe, Sheet s KE110083A EB -8 1 of 2 Projecl Name Nelsen (tiliiddie Schn6 Ground Surface Flevalror ift1 Loca€on Renton. WA — Datum Nrq Driller/Equipment BCreteC/Track RiQ Date SlarL'Finish 4(1 R 11 4; 1 Hammer Weighl]Urop 140# j10" Hole Diameter (in; r � 7 W io v Q� — Blows/Foot 5 E S0E °a 3 T cm (n E rjim L DESCRIPTION I 10 20 30 40 T�' I � Fill � F—F-7— Moist tD wet, brownish gray, silly SAND, with gravel and ❑rganics MDIM t0 Wet, Settle Wel, rust -stained brownish gray, Silty fine to medium SAND, with gravel. Wet, rust -stained brown ana gray, silty fine to medium SAND, with gravel Moist, bluish gray and brown, silty SAND, with gravel and organics. MD)sl, slightty ruse -stained brownish gray, 5Pty fine SAND, with gravel. G 15 15 4 Al �4 a g 6 3 4 i1 4 p 2D i I 12 4 13 12 25 Wet, very litsfe recovery, same I E S-7 'r 13 16 0 N Sampler Type (ST). m 2" OD Split Spoon Sampler (SPT) n No Recovery M - Moisture Logged by: JPL m fm 3" OD Split Spoon Sampler (D & M) U Ring Sample SZ Waler Level (} Approved by: 4 Grab Sample Shelby Tube Sample water Level at lime of drilling (ATD) Associated Garth Sciences. Inc. Geologic & Monitorinq Well Construction Loi r— Pro ecl Number Well Number 5hee1 Prclecl name Nelsen Middle School Location Renton WA - -- Elevation (Top of Well Casing) Surface Elevating, Water Level Elevation _ Date StarlFinish 4119111 4;1gj11 Drilling/Equipment BoreteclTrac Riq Acle Diameter din) 6" Hammer Weighb'Drop m 7 U � © WELL CONSTRUCTIONT m ! DESCRIPTION slush monument Fill Concrete 0 to 2 feet 5 I Bentonite chips 2 to 26.5 feet 1 I t' 2 -inch PVC casing 0 to 29 5 feet 20 Moist, brown, silty fine to medium SAND, with gravel and organics. 3 Moist to wet, same. 3 3 f 3 We:, same. L 2 5 7 5 '6 32 26 Moist to wet, rust -stained brown and gray, silly fire to medium SAND, with gravel and organics Moist to wet, with woody debris, same Undifferentiated Stratified Drift Wist, slightly rust -stained, silty fine to medium SAND, with gravel. 31Moist, brown, fine to coarse SAND, with gravel and si#t i 5014" z� 10/20 silica sand 26.5 to it 39-5 reef a C7 M Sampler Type (ST): d 2" OD Split Spoon Sampler (SPT) No Recovery M - moisture Logged by: JPL w Y OD Split Spoon Sampler (D & M) Ring Sample Water Level (4121111 ) Approved by; Grab Sample Shelby Tube Sample i Water Level a1 time of drilling (ATD) I Associated Earth Sciestces. 1c Geologic & Monitoring Well Construction LU T Project Number Well Number Sheet �! r KE110( EB -9 2 of 2 Protect Name Nelsen Middle Schoal ._._ Location Renton, WA Elevation (Top of Well ;:asrng) Surface Elevation {R) Waler Level Elevation _ Date Starl)Finish 411 g ;1 1 4,11.q 1 1 DrillmgrEquipment Boretec/TracK jg Hole Diameter (in) 61, -- Hammer Weight/Drop 140## t 30" a Ji 3 aE WELL CONSTRUCTIONY m ` DESCRIPTION 29 Moist, rust stained brownish gray, fine to coarse SAND, with gravel. 501E" l f ch PVC 0.010" Screen 29 5 to 39 5 feet Q I' i 35 ; 34 Wet, brownish gray, fine to coarse SAND, with gravel, f Screw cap 40 I 26 Wel, same 5075" Bonnterminated af40,9 feet on 4!19/11 i I i -45 i i I I -50 55 a c� h Sampler Type (ST): g © 2" OD Split Spoon Sampler (SPT) No Recovery 1`0 - Moisture Logged by: JPL 3" OD Split Spoon Sampler (D & M) U Ring Sample Water Level (4121111) Approved by: z Grab Sample Shelby Tube Sample 1 Water Level at time of dri}ling (ATD) Associated Earth Sciences, Inc. I Exploration LO R—ED Y Project Number Expioration Number Sheet KED 100$3A EB 11 1 of 1 Project Name Nelsen Middle School Ground Surface Elevalion (ft) Locallan Renton WA Datum Iy1A��— DrillerrEquipment Boretec/Track Rig_ Date Star/Finish Ail �i111 411 all Hammer Weight/Drop 140# / 30" Hole Diameter (in) a CD 5 CQ` T DESCRIPTION � _€ v Slows/Foot o m 10 20 30 40 ° Fill ! F] I Moist to wel, Slightly rust -stained brownish gray, silty fine to medium ` I S-1 SAND, wish gravel and Irace organics. A13 !7 5 i 5 I Moist, same - S -2 4 9 5 € Moist, rust -stained brown and gray, silty fine to medium SAND, with gravel S_3 and trace organics. Aq 4 �4 1p i Undifferentiated Stratified Drift Moist, rust -stained brownish gray, silty fine to medium SAND, with gravel S-4 , 2 d AI I 12 i I 15 i Moist, slightly rust -stained brownish gray, silly fine to medium SAND, with I I I S 5 gravel 8 ,32 69 Batlorn ar exploration boring at 15 5 feel I 20 I E E 25 I ' C f l EE 2" CD Split Spoon Sampler (SPT) No Recovery M - Moisture Logged by: JPL m m 3" OD Split Spoon Sampler (D & M) U Ring Sample V Water Level {) Approved by: ® Grab Sample Shelby Tube Sample= Water Level at time of driliing (ATD) Associated Eirth Sciences, tt,r. Exploration Lo Project Number xpio atio Number Sheet aE oo83A EB -12 of P'rOject Name Nelsen Middle _School Ground Surface Ela�,1alion ';Fl) _ �~- LDralion Rentor. WA Datum R€iA DriRer`FgApment Boretec/Track Rig HateStartrFinish _4199`11.41]_91 —<< Hammer Wei ht/Drop 14Q# /a"_ �---- g Hole Diameter (in) ----- A a S E E ! a a 3IOWSIFoOi F GT � DESCRIPTION 'm 10 20 30 40 � Fill I Moist, brawn, silty fine to medium SAND, with gravel and organics. 5-1 I J S-2 .1 J �` I S-5 20 1 25 Moist, same. Undifferentiated Stratified drift 'hoist, brown, fine to medium SAND, with gravel and siltier zones. Moist to wet, brownish gray, fine to medium SAND, with trace grave[ Moist, brownish gray, fine to medium SAND, viii silt and t ace gravel. i i Ba0.orn or expioralion boring at 16.5 feet IB 5! 4 d A 14 7 7 2D 22 23 I IB 131 A17 14 I 15 25 23 i i N a C a � I t� a Sampler Type (ST): 2' OD Split Spoon Sampler (SPT) F] No Recovery M - Moisture m 3" OD Split Spoon Sampler (D & M) ® Ring Sample 5Z Water Level () e ® Grab Sample 0 Shelby Tube Sample i Water Level al time of drilling (A T D) Logged by- JPL Approves! by: Associated L�rth 5crences, Inc. Exploration Lo Project Number Exploration Number Sheet—� KE110083A EB-13 1 of 1 Project Name Nelsen Middle School Ground SUrfaCF Elevation (T. Location Renton. WA _ Datum Driller/Equipment B retec/Track Riq Date S1art'Fir sh R11 4!13111 1 _411 Hammer Weightl0rop 140# ! 30" Hole Diameter (in; 4^ N O L L ° 4 > ' W J Blows/FootC. E v 41 5 ro a (D LO Q E 3F 'r-' P k T DESCRIPTION " 10 20 30 ao 4 inches asphalt (two layers), 6 inches crushed rock Fill Moist, brawn, silty SAND, with gravel and asphalt pieces. I 5-i t8; 17:' d3 Moist, brownish gray, silty fine to medium SAND, with gravel f S-2 14 a Al a Moist. brownish gray, silty fine SAND, with gravel and trace wood debris. I S_3 LIQ 13, �3 21' 1 Same for 8 inches I ; Undifferentiated Stratified Drift S-4 Moist, rust-stained brownish gray, silly fine to medium SAND, with [race t8 13 r gravel 1 19 32 GRAIN SIZE ANALYSIS - MECHANICAL Date Project Project Na Soil Description 04/2212011 Nelsen Middle School KE110083A Sand little gravel trace silt Tested By Location EB/EP No125- Pt. Depth Intended Use Specification MS Onsite Eg-9 of moisture wet sample + TareWME mple Tare 335.62 Wt of moisture dry Sarnpie + Taremple wt + tare 764.83Wt of Tare mple Wt369.2NJt. of moisture Dry Sample mple Ory Wt 338.3Moisture % S ecitication Re uiremertts Sieve No. Diam. rnm Wt. Retained °/r, Retained % Passin Minimum Maximum 3 76.1 0.0 100.0 2.5 64 0.0 100.0 2 508 0.0 100.0 - 1.5 381 0.0 100.0 _ 1 25.4 0.0 100.0 _ 3/4 19 9.43 2.8 97.2 3/8 9.51 3838 11.3 88.7 #4 4.76 79.57 23.5 76.5 #8 2.3E 118.15 34.9 65.1 #10 2 126.97 37.5 62.5 #20 0.85 173.08 51.2 48.8 #40 0.42 247.63 73.2 26.8 #60 0.25 299.6288.6 114 _ 4100 0.149 318.66 - 94.2 5.8 #200 0.074 330.1 97.6 2.4 #270 0 053 335.25 99 1 1 0.9 _ US STANDARD SIEVE NOS. 314" NO No 1B NO 40 NO 200 100 so I w � I I w 40 I _- I_ 20 I I - .,.. i00 1Dl 1 0-1 4.01 Gravel Sand Silt and Clay Curse l=ine Coarse Medium Fine Grain Size, mm ASSOCIATED EARTH SCIENCES, INC. 911 5th Ave , Suile 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424 CRAW SIZE ANALYSIS m MECHANICAL Date Project Project No. Soil Description 04122/2011 Nelsen middle Schoo( KE110083A Sand with gravel trace silt Tested By Location EB/EP No IDepth Intended Use I Specification M5 Onsite EB -9 30' t VVI of moisture wet sample + Tare 1018.06 Total Sample Tare 521.15 Wtof moisture dry Sample + Tare 986.65 Total Sample wt + tare 986.65 Wt. of Tare 521.15 Tolal Sample Wt 465.5 M. of moisture Dry Sample 465.5 Total Sample Dry Wt 436-1 Moisture °ia 7% 00 100.0 Sieve No. Diam. mm Wt. Retained % Retained % Passing 4 Minimum v Maximum 3 76.1 0.0 100.0 _ 2.5 64 0.0 100.0 - - 2 50.8 00 100.0 1.5 381 0.0 100.0 1 25.4 32.3 7.4 92.6 314 19 32.3 7.4 92.6 318 9.51 77.14 17.7 82.3 _ #4 4.76 130.66 30.0 70.0 _ #8 2.38 198.59 45.5 54.5 410 2 214.6 49.2 50.8 #20 0.85 297.49 68.2 31.8 #40 0.42 363.73 83.4 16.6 #60 0.25 390.84 89.6 10.4 #1100 0,149 407.18 93.4 6.5 #200 0.074 420.17 964 3.6 #270 0.053 425.44 1 97.6 2.4 _ US STANDARD SIEVE NOS. 314' NO 4 NO 16 NO 40 NO ADD 100 , - - ---- - I ,J I I ! _C 60 40 20 -- .. 1DO Gravel Grain Size, mm A ss O CIA rED Ea R rN SCIENCES, INC.9 r 1 5th Ave Suite 100 Kirkland. WA 98033 425-827,7701 FAx 425.827-5424 Sand Silt and Clay Coarse Fme Coarse Medium Fine Grain Size, mm A ss O CIA rED Ea R rN SCIENCES, INC.9 r 1 5th Ave Suite 100 Kirkland. WA 98033 425-827,7701 FAx 425.827-5424 Date Project Project No. Soil Description 04/29/2011 Nelsen Middle School KE110083A Sand with silt little gravel Tested By Location EB/EP No JDepth Intended Use/ Specification M5 Onsite EB -13 5' 319.3 4Vl. of moisture wet sample + Tare 29463 Total Sample Tare 395.59 Vd1 of moisture dry Sampie + Tare 274.81 Total Sample wt + tare 751 Wt. o1 Tare 913 Total Sample Wt 355.4 Wt. of moisture Dry Sample 17551 Total Sample Dry Wt 319.3 Moisture % 11% 0.0 100.0 I c-tC-k o Sieve No Diam. mm Wt, Retained % Retained % Passing Minimum Maximum 3 76.1 0.0 100.0 - - 2-5 64 0.0 100.0 2 50.8 0.0 100.0 1.5 38.1 0.0100.0 1 25.4 0.0 w 100.0 _ 3/4 19 13.8 4.3 95.7 318 9.51 2712 8.5 91.5 _ #4 4.76 48.05 15.0 85.0 #8 2.38 6526 20.4 79.6 #10 2 69.22 21-778.3 _ #20 0.85 87.14 27.3 72.7 - #40 0-42 116.61 37.1 62.9 _ #60 0-25 163.43 51.2 48.8 #100 0.149 195.96 61.4 38.6 #200 0.074 218.37 66.4 31.6 _ #270 1 0.053 226.68 71.0 29.0 _ US STANDARD SIEVE NDS 314" NO 4 NO 16 NO 40 NO 200 i 1pG 10 1 [l 1 n n� Gravel Sand Silt and Clay Coarse Fine Coarse Medium Fine Grain Size, mm ASSOCIATED EARTH SCIENCES, INC. 911 5th Ave., Suite 100 Kirkland, WA 98033 425-827-7701 FAX 425-827-5424 Associated Earth Sciences, Inc. Percent Passing #200 ASTM D 1140 Date Sampled Project Project No. Soil Description 04/22/2011 Nelsen Middle School KE110083A Sand with sift Tested By Location EB/EP NoDepth 74.5 MS Onsite 298 Actual Dry Weight 513.5 Sample I.D. EB -1i 2.5' EB -122.5' Wet Weight 891 .7 825.5 Dry Weight 827 4 751.0 Water Weight 64.4 74.5 Pan 31 3.) 298 Actual Dry Weight 513.5 452.7 Percent of Water Weight 12.5 16.5 After Wash Weight 66-1 F< 614.1 Percent Passing #200 32.0 30.2 ASSOCIATED EARTH SCIENCES, INC. 911 51h Ave . Suite 100 Kirkland, WA 98033 425.827-7701 FAX 42"27-5424 Associated Earth Sciences, Inc. Moisture Content ASTM ® 2216 Date Sampled Project Project No. Soil Description 04/22/2011 Nelsen Middle School KE110083A Tested By Location EB/EP No. Depth Various MS Onsite Sample 10 EB -5 2.5' EB -10 5' EB -11 2.5' Wet Weight + Pan 465.4 562.7 361.0 Dry Weight + Pan 4353 521.4 330.5 Weight of Pan 99.3 100.1 101.6 Weight of Moisture 30.1 41.3 30.5 Dry Weight of Soil 336.0 421.3 228.9 % Moisture 9.0 9.8 13.3 Sample ID EB -11 15' E8-12 2.5' Wet Weight+ Pan 495.9 281.5 Dry Weight + Pan 4594 260.6 Weight of Pan 100.8 94.9 Weight of Moisture 36.5 20.8 Dry Weight of Soil 358.6 165.8 % Moisture 10.2 12.6 ASSOCIATED EARTH SCIENCES, INC. 911 51h Ave , Suite 3 DO Kirkkand, WA 98033 425-827-7701 FAX 425-927-5424 APPENDIX F Bond Quantities, Facility Summaries, and Declaration of Covenant Figure 1.......o. Bond Quantities Worksheet Figure 2......... Flow Control and Water Quality Facility Summary Sheet Figure 3......... Declaration of Covenant APPENDIX G Operation and Maintenance Manual APPENDIX H TESL Analysis and Design Figure 1......... Temporary Sediment Pond Calculations Project Subject 'T. - - 1ti�iihlTc ' ( e Address -- Date — Project No. Phone Fax # # Faxed Pages Dy i 1 s ?,n rz,T .t f'r r cr.-r�.e' Kl Ws -r _ J ❑ Page 5, of _ Calculations ❑ Fax ❑ Memorandurn Meeting Minutes Telephone Memo CDCklticir, ��e V% Ci 7 k -r, a,U 4 C-�-W ...KC L' C ~ C?:w✓:,� �'me........,., r,�,._,....� �.. �o:5c�, _�asWG �.':eo.s�•rtr,; '° ,?ur�cfA�c.� ,?,red. EE0. !jVF T{^l'.. r i 1 Civil Engineers Structural ,engineers Landscape Architects Community Planners Land Surveyors Neighbors ❑TACOMA as 2215 N. 30th 5f. l Suite 300 Tacoma, WA 98403-3305 253.383.2422 253.383.2572 FAX ❑ SEATTLE 1200 6th Avenue '- Suite 1620 Seattle, WA 98101-3123 If this does not meet with your understanding, please contact us in writing within seven days. THANK YOU. 206.287.2425 206.267.2429 FAX Subject .� - With/To Address — Date Qbki - t2- ZZ_ Project INC. Phone Fax # # Faxed Pages By t." r " Page o' Caiculabons ❑ Fax ❑ Memorandum ❑ Meeting Minutes U Telephone Memo �..�:oo.=., .,=.�_r-+�,....�,..�.m...y..�..�-._.�....�::��v i�.7` v,�e C. t- f�'.- r� 0. ... �,•�a tic r � L= rey use 14z c) ,v ` �u� _E L Civil Engineers Structural Engineers Landscape Architects Community Planners Land Surveyors Neighbors QV T l Yi (CjY'r 4� f 15�".� tCl t'EYf' ❑TACOMA T 2215 N. 30th St. nF Suite 3D0 ,r 1 c �C� Tacoma, WA 98403-3305 253.383.2422 253.383.2572 FAX 0. p ❑ SEATTLE 1200 6th Avenue Suite 1620 Seattle, WA 98101-3123 If this does Pat meet with your understanding, please contact us in writing within seven days. THANK YOtJ 206.267.2425 206,267.2429 FAX Landscape Architects Community Planners . r Land Surveyors -_ Neighbors ❑ TACOMA 2215 N. 301h St Suite 300 Tacoma, WA 98403-3305 253.383.2422 253.383.2572 FAX ❑ SEATTLE 1200 6th Avenue Suite 1620 Seattle, WA 98101-3123 If this does not meet with your understanding, please contact us in writing within seven days. THANK YOU. 206.267.2425 206.267.2429 FAX Subjacl tiro�a ,= ,. ar.-r. Phone _� Calculations ❑ Fax With/To Fax ti — - -- fvlemorandum AMU '04=1❑ Address _. 4 Faxed Pages - ❑ Meeting Minutes Date ; , ... j - l "C, By 4' E c i r r1 c C �< ` 1;,. r , , s , r . ;°_ ❑' Telephone Meirra Civil Engnreers ��4Y4W r.rs C_•,✓'.}.c-: tee, G4YG. i';l":'� f•i._G C:°_ " Structural Engineers Landscape Architects Community Planners . r Land Surveyors -_ Neighbors ❑ TACOMA 2215 N. 301h St Suite 300 Tacoma, WA 98403-3305 253.383.2422 253.383.2572 FAX ❑ SEATTLE 1200 6th Avenue Suite 1620 Seattle, WA 98101-3123 If this does not meet with your understanding, please contact us in writing within seven days. THANK YOU. 206.267.2425 206.267.2429 FAX Project: Nelson Middle School Project Number: 211128.10 Task: Sediment Pond Calculations - KCRTS output Date- December 22, 2011 Performed By: Michael R. Norton, P.E. Flow Frequency Analysis Time Series File:sed.tsf ProjectLocation:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) Prob (CFS) 0.592 4 2/09/01 12:45 0.372 7 1/06/02 1:00 1.32 3 12/08/02 17:15 0.275 8 8/26/04 1.00 1.37 2 11/17/04 5:00 0.548 5 10/27/0510:45 0.542 6 11/24/06 1:00 2.51 1 1/09/08 6:30 Computed Peaks 0.500 0.372 -----Flow Frequency Analysis ------- Peaks -- Rank Return Prob (CFS) Period 6 2.51 1 --1-6-0 0-0 1.37 225.00 0.960 3�� 0.592 4 5.00 0-800 0.548 5 3.00 0.667 0.542 6 2.00 0.500 0.372 7 1.30 0.231 0.275 8 1.10 0.091 2.13 50.00 0.980 S34 CONTRO] . S"I R1�CTCkDS 1sfcT.�i?DS o,� A 'AL.Y51:5 Riser Overflown The riomograph in l~igure. 53.4.H may be used to deienmine the head (in feet) above a riser of'give.li diameter alld for a given flow (usually the 100 -year peak flow for developed conditions). A FIGURE 5.3.4.11 RISER INFLOW CURVES Qweir==9739 DH3r2 Qorirrce=3.7$2 D2H112 Q in cfs, D and H in feet Slope change occurs at weir -orifice transition In 2009 Surface Water Design Manual 1/9/2009 5-47 7A C'GA4a 2215 North Nth Street Suite 300 Tacoma, WA 88403-3350 253.3832422 253.383.2572 FOM 5FAr71 r 1200 61h Avenue Suite 1620 Seattle WA 9 610 1-3 1 23 206,267-2425 TEE 206,267.2429 Ear www.ahb).com