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Geologlc and Geotechnlcal Design Olympic Pipe Line Milepost 109 Landslide Stabilization Project Renton, Washington for Olympic Pipe Line Company March 26, 2010 GEoENGINEERS CJ 8410 154'" Avenue NE Redmond, Washington 98052 425.861.6000 City of Renton Planning Division A, ,i 1 9 :iU Geologic and Geotechnical Design Olympic Pipe Line Milepost 109 Landslide Stabilization Project Renton, Washington Prepared for: Olympic Pipe Line Company 2319 Lind Avenue Southwest Renton, Washington 98057 Attention: Ed Smith Prepared by: GeoEngineers, Inc. 8410 154'" Avenue NE Redmond, Washington 98052 425.861.6000 A. Brooke Asbury, LG Project Geologist Shaun D. Stauffer, PE, LEED AP Associate SRH:ABA:SDS:nlu:csv File No. 0894-188-00 March 26, 2010 A. BROOKE ASBURY :7:a"~:=rlf- Principal REDM:\0\0894188\00\Finals\089418800 Geologic and Geotechnical Report.doc Disclaimer: Any electronic fonn, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Copyright© 2010 by GeoEngineers, Inc. All rights reserved. GeoENGINEERS CJ Geologic and Geotechnical Design Report Rerrtcn, Washington Table of Contents INTRODUCTION .......................................................................................................................................... 1 SITE DESCRIPTION ••.•.•............................................•......•......•....•....•.•.••.•....•......•......•......................•....•.... 1 Surface Conditions ................................................................................................................................. 1 Landslide Description ............................................................................................................................ 2 Site Geology ............................................................................................................................................ 2 Subsurface Explorations ........................................................................................................................ 2 GEOTECHNICAL CONCLUSIONS AND RECOMMENDATIONS .................................................................. 3 Critical Areas Evaluations ...................................................................................................................... 3 Slope Stability Analyses ......................................................................................................................... 3 General ............................................................................................................................................ 3 Static Analysis ................................................................................................................................. 4 Landslide Stabilization Design .............................................................................................................. 4 Slope Preparation ........................................................................................................................... 4 Slope Reconstruction ...................................................................................................................... 5 Additional Drainage Improvements and Runoff Control Measures ............................................. 5 Weather Considerations ................................................................................................................. 6 Temporary Sedimentation and Erosion Control ............................................................................ 6 Slope Maintenance ......................................................................................................................... 6 Estimated Volumes ................................................................................................................................ 7 Project Schedule .................................................................................................................................... 7 DRAINAGE EVALUATION ............................................................................................................................ 7 Site Drainage Conditions ....................................................................................................................... 7 Drainage Design ..................................................................................................................................... 8 Drainage Basin Summary ...................................................................................................................... 8 Calculated Design Flows ................................................................................................................. 8 LIMITATIONS .............................................................................................................................................. 9 REFERENCES .......................................................................................................................................... 10 GEOENGINEER~ March 26, 2010 Page i Flle No. 0894·18S.OO Table of Contents (continued) LIST OF FIGURES Sheet 1. Site Plan Sheet 2. Grading Plans Sheet 3. Drainage Plan and Details Sheet 4. TESC Plan APPENDICES Appendix A. Field Explorations Figure A-1 -Key to Exploration Logs Figures A-2 through A-4 -Log of Hand Augers Figures A-5 through A-8 -Log of Drive Probes Appendix B. Slope Stability Analyses Appendix C. Drainage Evaluation Calculations Appendix D. Report Limitations and Guidelines for Use Page ii Man:h 26, 2010 GeoEngineers, Inc. FlleNo. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington Geologic and Geotechnical Design Report Renton, Washington INTRODUCTION GeoEngineers, Inc. is pleased to provide this report summarizing our landslide evaluation and stabilization design for the landslide located adjacent to the Olympic Pipe Line (Olympic) easement at Milepost 109 in Renton Washington. Olympic operates 16-inch and 20-inch-diameter petroleum-products pipelines that extend through the City of Renton. A landslide was discovered in January, 2009, located along the west side of the cleared pipeline easement (parcel number 1623059137) approximately 150 feet west of Laurel Drive and approximately 300 feet south of Hemlock Drive in Renton, Washington. The location of the site is shown on the Vicinity Map, on Drawing No. D-M-108, Sheet 1. The headscarp of the landslide is currently 6 feet away from the 20-inch petroleum-products pipeline. Therefore, Olympic is proposing to stabilize the landslide by constructing a rock buttress and site drainage improvements to protect the pipelines from future landslide activity. SITE DESCRIPTION Surface Conditions The 16-inch and 20-inch petroleum-products pipelines are oriented generally north-south within the maintained easement which is vegetated with mowed grass. The pipeline easement extends through vacant, undeveloped King County property. A residential development is located on the property to the east, upslope of the easement. The area between the residential development and the easement is vegetated with alders, firs, and blackberries. The area to the west of the pipeline easement consists of a steep, undeveloped forested drainage that descends down to the Cedar River Valley. The site features are shown on the Site Plan and Grading Plan, Sheets 1 and 2. We completed a critical areas field reconnaissance of the site and completed an office review of available critical areas information sources, including: • Washington Department of Natural Resources (WDNR) FPARS mapping system (WDNR, 2008), WDFW's SalmonScape system (WDFW, 2008a), • King County I Map GIS system (King County, 2008), • National Wetlands Inventory (NWI) maps (United States Fish and Wildlife Service [USFWSJ, 2009), and • City of Renton Critical Area Maps (2009). These data sources, along with our site investigations, indicate that steep west-facing slopes, a wetland area, and a stream are located at the site. The steep slopes are immediately adjacent to the pipeline easement, where the landslide is located. A non-fish-bearing stream (WDNR, 2008) is located at the toe of the slope, approximately 80 feet below the landslide. A wetland boundary was delineated within the Olympic easement by a GeoEngineers wetland biologist. The wetland delineation was conducted in general accordance with the U.S. Army Corps of Engineers and Washington State Department of Ecology's wetland delineation procedures. The wetland is located approximately 210 feet north of the landslide and appears to be entirely within GeoENGINEER~ March 26, 2010 Page 1 FIie No. 0894-188-00 Geologic and Geotechnical Design RePort Renton, Washington the cleared pipeline easement. The project area is therefore more than 200 feet away from the wetland area. Landslide Description The recent landslide was discovered by maintenance crews following heavy rain and rain-on-snow events in January, 2009. The headscarp of the slide is located along the west side of the easement, approximately 6 feet west (downslope) of the 20-inch pipeline. The headscarp is roughly 30 to 40 feet wide. The exposed landslide scarp extends approximately 50 feet down the slope where the majority of the slide debris was deposited. Some debris continued to flow down the slope into a small stream channel and appears to have temporarily blocked the channel. The stream has since flowed over and around the slide debris. The landslide and its surrounding features are shown on the Site Plan, Sheet 1. There is currently a stormwater outfall pipe, which exits from a stormwater detention pond on the adjacent mobile home development, located approximately 150 feet upslope/east of the landslide. The outfall pipe from the detention pond ties into a 20-inch HDPE tightline pipe installed by the City of Renton in 2002 as shown on the City of Renton Drawing Number D-283103 (City of Renton, 2000). Based on erosion features upslope of the landslide and evidence of surface water flow across the pipeline easement, water levels may have overtopped the stormwater pond during severe storm events in the past resulting in stormwater flowing down the slope and into to the slide area. In its current state, the slide is unstable with exposed soils susceptible to erosion. It is likely that slide movement will continue at the site during periods of heavy precipitation. until the landslide is stabilized and drainage improvements are implemented. Therefore, if the slide expands, it could expose and/or damage the pipeline(s). Site Geology We reviewed the "Geologic Map of Renton, 1:100,000 Quadrangle, Washington," (D.R. Mullineaux, 1965) and the 2007 Geologic Map of King County (Booth et a/., 2007). Soils mapped in the vicinity of the landslide consist of glacial till overlying outwash deposits. Glacial till in this area is generally underlain by advance outwash and Lawton clay, all associated with the Vashon glaciations or the period immediately preceding the Vashon glacial advance. The soils exposed in the landslide scarp appear to be glacial till consisting of silty sand with gravel, which was transported and deposited under ice. These deposits are generally very dense. Transitional beds of siltjclay with sand are typically encountered between the glacial till and outwash deposits. The transitional beds are generally medium stiff to stiff. Subsurface Explorations We completed 3 hand augers and 4 drive probe explorations during our site visit on June 26, 2009 to evaluate subsurface soil and groundwater conditions in the project area and help define the depth of the landslide failure surface. The approximate locations of the hand augers and drive probes are shown on the Grading Plan, Sheet 2. The logs of the hand augers and drive probes, as well as a more detailed description of our exploration activities are presented in Appendix A. Page 2 March 26, 2010 GeoEngjneer.;, Inc. FIie No. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington Soil conditions encountered in the hand augers HA-1 and HA-3 generally consisted of dense silty fine to coarse sand with gravel. Refusal on cobbles was encountered in hand auger HA-1 at a depth of 2.5 feet and at a depth of 2 feet in hand auger HA-3. Hand auger HA-2 encountered loose silty fine to coarse sand with gravel to silt with sand and gravel to a depth of about 1.5 feet. Below that depth, medium stiff elastic silt to fat clay with trace sand and occasional gravel was encountered. The hand auger was completed to a depth of about 5 feet below grade. Soil samples are not collected from drive probes. The drive probes were used to supplement the hand augers and to provide additional information on the relative density of the soil. The drive probe explorations were completed by driving a '12-inch-diameter steel pipe into the ground using an 11-pound hammer, free-falling approximately 39 inches. The blows required to advance the pipe in 6-inch increments were recorded. Drive probe refusal criteria was considered to be greater than 50 blows per 6 inches. We used an empirical equation provided by Kaler (1999) to convert drive probe blows to standard penetration test (SPT) equivalents. The drive probe logs show the depths at which the soil density changes. The SPT-equivalent data show an increase of soil consistency from very loose at the ground surface to medium dense at approximately 4 to 5 feet below ground surface. GEOTECHNICAL CONCLUSIONS AND RECOMMENDATIONS Critical Areas Evaluations We evaluated the project area with regard to Critical Areas, as defined by Renton Municipal Code (RMC) and presented on the City of Renton Critical Areas Maps (City of Renton, 2009). The Critical Areas mapping indicates that the site is located within an Erosion Hazard Area, a moderate Landslide Hazard Area and contains Steep Slopes that range from 15 to 90 percent. Based upon the presence of slopes in excess of 40 percent and the recent landslide activity, much of the site is located within a Very High Landslide Hazard Area (VHLA), as defined by RMC 4-3-050 (J)(l)(b)(iv). The project area is also located within Zone 2 of the Aquifer Protection Area. We do not anticipate adverse impacts to the project areas as a result of the planned landslide stabilization, provided that the geotechnical recommendations, the temporary erosion and sedimentation plan (TESC) and the proposed additional surface water collection systems are incorporated into construction. Furthermore, it is our opinion that if proper erosion control measures are implemented during construction and site restoration and revegetation is completed, the proposed landslide stabilization will increase the overall stability of the slope and reduce the potential for future erosion. Slope Sta blllty Analyses General We performed stability analyses of the proposed landslide stabilization using the computer program Slope/W, Version 7 .14, developed by Geo-Slope Int, Ltd. The slope stability analyses are based on the site geometry and soil and groundwater conditions encountered in our subsurface explorations and geologic reconnaissance. The soil strength parameters used in the analyses were determined by a combination of drive probe data from the explorations, back calculations (based on the slide geometry), and our professional judgment. The results of our stability analyses are GEOENGINEER~ March 26, 2010 Page 3 Flle No. 0894-lSB-OO Geologic and Geotechnical Design Report Renton, Washington shown on Figures B-1 and B-2 as presented in Appendix B and summarized in the following paragraphs. Static Analysis A global failure was analyzed for the existing landslide and adjacent slopes for the existing conditions with elevated groundwater. The global existing failure was assumed to occur in a region that included all of the moderately steep slopes, resulting in a rotational/translational block failure mode. The failure surface was assumed to occur at a depth of about 4 to 5 feet in loose silty sand. These assumptions are consistent with the failure mechanism of landslides occurring in this region under similar geologic conditions and observed during our site visits. The soil strength parameters for the disturbed native soils within the landslide mass were back-calculated assuming a factor of safety of 1.0. The results of this stability analysis are shown on Figure B-1. We also evaluated the stability of the slope after constructing the rock buttress and drainage improvements, as shown on Figure B-2. The analysis assumes a saturated condition for the slope with groundwater level at the surface within the slide area. The proposed stabilization design includes the removal of disturbed, low-strength soil from the slide scarp and placement with riprap as described in the Landslide Stabilization Design section below. The following table presents the soil parameters utilized in our slope stability analyses. Soll Unit Sataraud Unit Wel&M Coheelon F-AR&te (pcl) (pol) (dee) Native Soils (above slide) 120 200 28 Glacial Soils 130 200 34 Stabilization material -rip rap 150 0 45 Typical acceptable factors of safety for constructed landslide mitigation are 1.25 or higher. The results indicate that the landslide stabilization design with interceptor trench drains has a factor of safety of about 1.35 (Figure B-2). Therefore, it is our opinion that the landslide stabilization design has an adequate factor of safety for static conditions. Landslide Stabilization Design We recommend that the landslide at the site be repaired to protect the existing petroleum-products pipelines located immediately upslope of the landslide. We recommend excavating the loose landslide material, cutting benches into the firm, undisturbed native soils and backfilling the area with rip rap. We also recommend additional drainage elements be installed above and below the slide to help control surface water and groundwater. Our recommendations for these elements are discussed in the following sections. Details regarding our recommendations are attached on Sheets 1 through 4 of the project drawings with a detailed outline of our recommendations presented on Sheet 4. Slope PreparatJon Prior to constructing the rock buttress, the landslide debris and loose/disturbed soil that has accumulated on the slope should be removed from the landslide stabilization area. On-site soil may not be used as backfill behind the rock buttress planned for this project. The loose/disturbed Page 4 March 26, 2010 GeoEngineers, Inc. FlleNo. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington soil should be excavated down to firm, undisturbed soil and be removed from the site. Based on our field explorations and observed site conditions, we expect that the excavations will need to extend to a depth of no more than 8 feet below the existing ground surface. We recommend that 2-to 3-foot-high benches be cut into the firm, undisturbed subgrade soils to provide a stable and relatively level surface for rock placement. Slope Reconstruction Once the slide area has been prepared as described above, we recommend that the slope be reconstructed by placing rip rap to form a rock buttress. Prior to rock placement, we recommend that a 16-inch-diameter perforated HDPE pipe be placed at the bottom of the excavation, along the toe of the landslide (oriented north-south) to collect water from the rock buttress. The perforated pipe should be surrounded by gravel drain rock, wrapped in a non-woven geotextile fabric. The perforated pipe should tie into a 16-inch tightline HDPE pipe to transmit the water collected in the perforated pipe out of the landslide stabilization area and should discharge into a rock-lined swale constructed downslope of the area (see Sheets 2 and 3). After installation of the drain pipe, we recommend placing rip rap (1-to 2-man rock) to reshape the slope to a final inclination of no steeper than 1.5H:1V (horizontal:vertical). The rip rap should be compacted by tamping in place with the bucket of the excavator. We recommend that the new slope meet the top of the existing slope. Additional Drainage Improvements and Runoff Control Measures Proper drainage is imperative for long-term slope stability. In our opinion, the uncontrolled flow of surface water was a major factor contributing to the destabilization of the slope. We recommend construction of an interceptor trench drainage system upslope of the landslide and a rock-lined swale downslope of the landslide to drain water from the landslide repair area to a stable area at the bottom of the slope. A north-south oriented interceptor trench drainage system should be constructed along the east side of the pipeline easement to collect water from upslope (as shown on Sheet 2 and on Sheet 3, Detail 1). The interceptor trench drain will tie into an east-west oriented cross trench drain (Sheet 3, Detail 2) to transmit water across the pipeline easement to the head of the landslide repair area. The trench drains will generally consist of a 16-inch diameter perforated HDPE pipe surrounded by gravel drain rock, wrapped in a non-woven geotextile fabric. A 12-inch layer of quarry spalls will be placed above the drain rock and fabric to form a free-draining, stable layer at the ground surface. We also recommend constructing a rock-lined swale, which should extend from the toe of the rock buttress and discharge into a riprap outfall protection area constructed above the Ordinary High Water Mark (OHWM) of the unnamed stream at the bottom of the slope. An approximately 12- inch-thick layer of swale rock should be placed within the excavated swale, forming a shallow trapezoidal-shaped channel. The swale rock size should vary from 2 to 12 inches, with a medium diameter of 8 inches. Swale geometry and swale rock gradation requirements are shown on Sheet 3, Detail 3. A riprap outfall protection structure should be constructed at the downslope end of the rock-lined swale and should consist of an apron, at least 15 feet wide and 3 feet deep to key-in riprap (1 to 2 man) at the outfall of the rock-lined swale (Sheet 3, Detail 4). GeoENGINEER~ March 26, 2010 Page 5 file No. 0894·1B8-00 Geologic and Geotechnical Design Report Renton, Washington Weather Considerations Work should be scheduled for periods of dry weather to reduce the risk of slope instability. During dry weather the soils will be less susceptible to disturbance, and will provide better support for construction equipment. The wet weather season generally begins in October and continues through May in western Washington; however, periods of wet weather may occur during any month of the year. For earthwork activities during wet weather, we recommend that the following steps be taken: • Earthwork activities should not take place during periods of moderate to heavy precipitation. • Slopes with exposed soils should be covered with plastic sheeting when not being worked. • The contractor should take necessary measures to prevent on-site soils and fill soils from becoming wet or unstable. • The contractor should cover all soil stockpiles that will be used as structural fill with plastic sheeting. • Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practical. Temporary Sedimentation and Erosion Control In our opinion, the erosion potential of the existing on-site soils is moderate to high because of the presence of the steep slopes. The amount and potential impacts of erosion are partly related to the time of year that construction actually occurs. Since the project is scheduled for the dry season (July, 2010), it is our opinion that the potential for erosion and sedimentation can be controlled by the measures recommended below. Erosion and sedimentation control measures may be implemented by using a combination of silt fencing, a stabilized construction entrance and access road, and placement of mulch or jute fabric placed over exposed soil until vegetation is re-established. All disturbed areas within the pipeline easement or surrounding areas should be re-seeded with the Revegetation Seed Mix (Sheet 4) and covered with mulch as soon as possible. Erosion and sedimentation control measures should be installed prior to the start of excavation or fill activities and should be maintained in accordance with the requirements of the City of Renton, and the details presented in the TESC Plan, Sheet 4. Slope Maintenance Although the site slopes are considered generally stable against deep-seated failure, excessive disturbance and/or poor site drainage can destabilize the near-surface soils. At no time should loose, uncontrolled fill or debris (including organic debris) be cast over or placed on the slope. The disturbance to the slope should be kept to a minimum during and after construction. To reduce the risk of erosion and surface soil movement during construction, we recommend that the slopes be protected by placing a silt fence along the toe of the slope immediately below the work area. Proper maintenance of vegetation on steep slopes will further reduce the potential for surface soil movement. Page 6 March 26, 2010 GeoEngineers, Inc. File No. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington Estimated Volumes The total estimated volume of soils to be excavated is approximately 320 cubic yards. The total estimated volume of temporary and permanent fill material is approximately 780 cubic yards. The actual excavated volume and fill volume may be somewhat greater than the in-place volume of soil due to bulking of the excavated soils and the compaction of the fill material. Of the total fill volume, we estimate the following approximate volumes for each fill type: 500 cubic yards (135 tons) of riprap, 43 cubic yards (11 tons) of quarry spalls and swale rock, 25 cubic yards (7 tons) of gravel drain rock, and approximately 210 cubic yards (56 tons) of crushed rock for road surfacing. Project Schedule The project is scheduled to begin in July, 2010. The work will take approximately 4 weeks to complete. DRAINAGE EVALUATION Site Drainage Conditions The proposed landslide stabilization is located on a portion of Parcel Number 1623059137, owned by King County. Parcel Number 1623059137 is currently undeveloped and densely vegetated with firs, deciduous trees and brush with the exception of a utility corridor shared by Olympie's pipelines and Seattle City Light's electrical transmission lines. The utility corridor is primarily vegetated by mowed grass. Surface water in the immediate vicinity of the project generally flows westerly to an unnamed stream that flows from north to south in the eastern portion of the parcel. The property located to the east of the proposed project (Parcel Number 1623059002) and is owned by the Sunnydale Mobile Home Community. Based on utility drawings and information obtained from the City of Renton Public Utilities Department, storm water from the southern portion of the mobile home development generally flows into existing catch basins and a drainage system that ties into a detention pond, located in the southwest corner of the parcel, as shown on Sheet 1. It is our understanding that storm water flows into Catch Basin No 26 (shown on Sheet 1, just west of the pond) and then into the detention pond. When water levels in the pond are at approximate elevation 304.5, water flows back through Catch Basin No. 26 and is tight-lined downslope through a 20-inch HDPE pipe. The 20-inch HDPE tightline is within a proposed drainage easement that crosses King County's Parcel Number 1623059137. The City replaced the tightline in 2002, replacing an existing corrugated metal pipe (CMP) outfall with an HDPE tight-line, as shown on the City of Renton Drawing Number D-283103, Roll 191, FR-115 (City of Renton, 2000). The original CMP drainage system is shown on 1983 drawings by Group Four for the Sunnydale Mobile Home Community grading and drainage plans (City of Renton Drawing Numbers 136301 through 136313, Roll 203). The water discharges into an energy dissipater and then into the stream at the bottom of the slope at approximate Elevation 90 feet. It appears that the detention pond may have filled and overlapped in the past and that the overflow from the pond has flowed across the existing access road located west of the pond. The water then flowed down the slope to the west of the road, through a small ravine and onto pipeline easement on King County's Parcel (Number 1623059137), as shown on Sheet 1. It is also our GEOENGINEER~ Man:h 26, 2010 Page 7 File No. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington understanding that the City repaired a small landslide along this overflow pathway, just west of the road at the top of the ravine in 1994. Drainage Design Based on our review of available information, our site visits, and our drainage calculations, the landslide stabilization project has been designed to accommodate runoff from surface water upgradient of the proposed rock buttress and the water collected within the rock buttress and discharged into the proposed rock-lined swale downslope of the landslide area. This area, approximately 0.38 acres, will include runoff from the proposed rock buttress area, the slope upgradient of the landslide repair, as well as runoff from a portion of the contributing area adjacent to the detention pond and the access road. These areas are summarized below and shown on the Drainage Evaluation Plan, Sheet 4. The new impervious area created by construction of the rock- lined outfall swale is considered negligible for the purpose of this study and therefore is not included. It is assumed that runoff from the southern portion of the mobile home development drains into the detention pond and is tight-lined downslope and does not contribute to run-off into the project area. Upon completion of this project. all vegetated surfaces disturbed during construction will be re- seeded with Erosion Control Grass Seed Mix (per Washington State Department of Transportation standards for utility easements), as shown on Sheet 4. Existing access roads will be dressed with gravel and treated with appropriate temporary and permanent erosion control measures. Olympic will monitor the site following the project to ensure that all restoration efforts are successful. It is estimated that about 1 to 2 vehicle trips per year will be required at the proposed landslide repair. As a result. the projected traffic volumes for this project do not warrant "High Use" site standards, and therefore, "High Use" site standards are not applicable to this project. Drainage Basin Summary The drainage areas shown on Sheet 4 are summarized below: Area 1-Rock Buttress Area 2 -Gravel Access Road and Ravine Area 3 -Grass Covered Area Area 4 -Light Forest Total Tributary Area 0.04 acre 0.10 acre 0.12 acre 0.13 acre 0.38 acres The combined runoff from the areas described above will be collected by the on-site conveyance system within the landslide stabilization project area. All collected water will drain from the landslide stabilization area to a rock-lined swale constructed at the base of the rock buttress. Water from the swale will pass through a riprap outfall protection structure to dissipate energy before entering the unnamed stream at the bottom of the slope. Calculated Design Rows The surface water flow calculations for the landslide repair design were calculated using the Rational Method based on the Section 3.2.1 of the 2009 KCSWDM and 100-year rainfall rates. Page 8 March 26, 2010 GeoEngineers, Inc. FlleNo. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington Based on our calculations, the 100 year peak runoff flowing into the swale is approximately 0.40 cutiic feet per second (cfs). Calculations are summarized in Appendix C. The pipe sizes and swale dimensions have tieen verified using equations developed from Manning's Equation and Section 4.2.1.2 of the 2009 KCSWDM. Based on our calculations, the 30 feet and 45 feet lengths of 16-inch HOPE piping at a slope of 1 percent currently designed for the landslide repair are capatJle of conveying runoff at a rate of approximately 8.1 cfs at pipe-full, and therefore has significantly greater capacity than the anticipated runoff from contritJutory area. Calculations are summarized in Appendix C. The flow channel of the rock-lined swale has a flow capacity calculated from a swale geometry of 5- feet wide at the top, 1-foot wide at the tiase and side slopes of 2H: 1V. The swale will tie approximately 80 feet long with a slope of atiout 35 percent. Based on these dimensions, the swale is capatJle of conveying runoff at a rate of approximately 12 cfs with a 1-foot freetioard. Calculations are summarized in Appendix C. Additional information is included in the Technical Information Report (TIR) Worksheet included in Appendix C. LIMITATIONS GeoEngineers has developed this report for Olympic Pipe Line Company, their authorized agents and regulatory agencies for the proposed Landslide Statiilization Project at Milepost 109 in Renton, Washington. Within the limitations of scope, schedule and tiudget, our services have tJeen executed in accordance with the generally accepted practices for slope statiility evaluations in this area at the time this report was prepared. The data and report should tie provided to prospective contractors for their tJidding or estimating purposes, out our report, conclusions and interpretations should not tie construed as a warranty of the sutJsurface conditions. This report has tieen prepared for the exclusive use of Olympic, their authorized agents, and regulatory agencies following the descritJed methods and information availatJle at the time of the work. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. The information contained herein should not tie applied for any purpose or project except the one originally contemplated. Any alteration, deletion or editing of this document without explicit written permission from GeoEngineers is strictly prohitJited and may jeopardize the success of the plans. Any other unauthorized use of this document is prohitiited. This document is intended to tie used in its entirety. If an excerpt is quoted or paraphrased, it must tie properly referenced. Any electronic form, facsimile or hard copy of the original document (email, text, tatJle, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored tJy GeoEngineers and will serve as the official document of record. Please refer to Appendix D titled Report Limitations and Guidelines for Use for additional information pertaining to use of this report. GEoENGINEERu:;ii Maroh 26, 2010 Page 9 File No. 0894-188-00 Geologic and Geotechnical Design Report Renton, Washington REFERENCES Booth, D.B., 2007, Geologic Map of King County, 1:100,000, GeoMap NW, University of Washington. City of Renton. 2009. Critical Area Code. http://www.codepublishing.com/wa/renton. Accessed June 2009. City of Renton. 2009. Critical Area Maps. http://rentonnet.org/internetapps/maps/index.cfm?fuseaction=products. Accessed June 2009. City of Renton. 2010. Municipal Code. http://www.codepublishing.com/wa/renton. Accessed February 2010 City of Renton, 2000. "Sunnydale Downstream Storm Replacement Project," Public Utilities Drawing Numbers D-283101 through D-283105, Roll 191, scanned 11-7-03. City of Renton File Drawing, 1983 Drawing by Group Four, "Sunnydale Mobile Home Community Grading and Drainage Plans." Public Utilities Drawing Number 136301 through 136313, Roll 203, Scanned 10-27-06. D. R. Mullineaux, 1965, Geologic Map of the Renton Quadrangle, Kind County, Washington, USGS GQ-405. Koler, T.E., 1999, Geotechnical Report for Freshwater Creek Watershed (working draft), prepared for The Pacific Lumber Company, p. 61. United States Fish and Wildlife Service. 2009. National Wetlands Inventory database. http://wetlandsfws.er.usgs.gov/NWl/index.html Accessed June, 2009. Washington State Department of Fish and Wildlife (WDFW), 2009. SalmonScape mapping system. http://wdfw.wa.gov/mapping/salmonscape/ Accessed June, 2009. Washington State Department of Natural Resources, 2009. FPARS mapping system. http://www3. wad n r .gov/ d n ra pp5/website/fpars/ def au lt.htm Accessed June, 2009 Williamson, D. A., 1994, Geotechnical Exploration-Drive Probe Method, Appendix 3.6, pp. 317-321, in U.S. Department of Agriculture, Forest Service, Slope Stability Reference Guide for National Forests in the United States, EM-9170-13, v. I, p. 321. Page 10 March 26, 2010 GeoEngineers, Inc. Alo No. D894-188-00 / ' I ---- / / ---· ·---·--- --------- / / ' / \ / I I \ I I I ( I I I / / /"' ,· . _ __..,,,. //,' / , / I,. -.. .,, .,. i ...... \ ·-\ ' ' I I .' ·' 'I ii I I \: \ \ \ \ / ! ,/ ..-----~ APPENDIX A Field Explorations ------- / --- ) / / --- \ /0 ---I ) ' I / \ '\ ', \ ____ _,,.~ :1 \ \ ' I \ ! I \ \ ..... .--· ------· ______ ___...- / Geologic and Geotectmlcal Design Report Reriton, Washington APPENDIX A FIELD EXPLORATIONS Subsurface conditions at the project site were evaluated by completing 3 hand augers and 4 drive probes on June 26, 2009. Hand augers were completed to depths of 2 to 5 feet below the ground surface, and drive probes were completed to depths of 1.5 to 6.5 feet below the ground surface. The hand auger explorations were advanced until our staff encountered refusal of the equipment. The drive probes were discontinued when it took 50 blows to advance the drive probe 6 inches. The explorations were coordinated and completed by a member of our staff who located the hand auger and drive probe explorations, obtained representative bulk soil samples from the hand augers, examined and classified the soils encountered, observed groundwater conditions, and prepared a detailed log of each exploration. Drive probe tests were completed by advancing a Vi-inch diameter steel pipe into the ground using an 11-pound hammer free falling from approximately 39 inches. The blows required to advance the pipe six-inches were recorded. The lead sections of the pipe were drilled with holes to allow entry of water. Water levels were checked after advancing the pipe every four feet. A more detailed discussion of the methodology can be found in the Slope Stability Reference Guide for National Forests in the United States, Volume 1 (Williamson, 1994). Soil encountered was classified visually in general accordance with ASTM D-2488-90 which is described on Figure A-1. A key to the symbols on the hand auger and drive probe logs is also provided on Figure A-1. Logs of the hand augers are presented on Figures A-2 through A-4 and logs of the drive probes are presented on Figures A-5 through A-8. These logs are based on our interpretation of the field data and indicate the various types of soil conditions encountered. They also indicate the depths at which these materials or their characteristics change; although, the change may actually be gradual. The soil densities noted on the logs are based on the probe depths obtained in the hand augers and blow count data obtained in the drive probes, as well as our judgment based on the conditions encountered. GeoENGINEER~ March 26, 2010 Page A-1 File No. 0894-lSS-00 SOIL CLASSIFICATION CHART MAJOR DIVISIONS SYMBOLS GRAPH LETIER TYPICAL DESCRIPTIONS COARSE GRAINED SOILS MORE THAN 50% RETAINED ON NO. ZOO SIEVE FINE GRAINED SOILS MORE THAN 50% PASSING NO. 200 SIEVE GRAVEL AND GRAVELLY SOILS MORE THAN 50% OF COARSE FRACTION RETAINED ON NO 4SIEVE SAND AND SANDY SOILS MORE THAN 50% OF COARSE FRACTION PASSING NO. 4 SIEVE SILTS AND CLAYS SILTS AND CLAYS CLEAN GRAVELS 1unLE OR NO f'NESJ GRAVELS WITH FINES D O 0 0 0 < D O "0 (APPRECIABI.EA"4QUNT ~//, OFFl>IES) I/~ CLEAN SANDS ILITILECH'I NO rnlES) SANDS WITH FINES ('"-CIABI.EAMOUNT '/./// /6«· .. OFFlNES) '////., GP GM GC SW SP SM SC ML WELL-GRADED GRAVELS, GRAVEL - SANO "41XTURES POORL Y--GRADEO GRAVELS GRAVEL. So\ND MIXTURES SILTY GRAVELS. GRAIi EL· SAND - SILT MIXTURES CLAYEY GRAVELS, GRAVEL SAND - CLAY MIXTURES WELL-GRADED SANOS. GRAVELLY -cs POORL Y--GRADED SANDS. GRAVELLY SANO SILTY SANOS, SANO· SILT MIXTURES CL.AYEY SANDS. SANO -CLAY MIXTURES INORGANIC SILTS. ROCK FLOUR. CLAYEY SILTS WITH SLIGHT PLASTICITY / /~ INORGANICCLAYSOFLCJNTO '//// CL MEDIUMPL.ASTICITY,GRAVELLY LIQUID LIMIT '/ / / / CLAYS, SANDY CLAYS, SILTY CLAYS, LESS THAN 50 H-+-f-.ft----+-""-'-'~"'~'~'--------1 LIOUIO LIMIT GREATER THAN 50 I J.'. l ., ' OL MH CH OH ORGANIC SIL TS ANO ORGANIC SILTY CLAYS OF lCIN PLASTICITY INORGANIC SILTS. MICACEOUS OR OIATOMACEOUS SILTY SOILS INORGANIC CLAYS Of HIGH PL.ASTICITY ORGANIC ClAYS ANO SIL TS OF MEDIUM TO HIGH Pt..ASTICITY HIGHLY ORGANIC SOILS PT PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANIC CONTENTS NOTE: Multiple symbols are used to indicate borderline or dual soil classifications Sampler Symbol Descriptions [] 2.4-inch I.D. split barrel [] Standard Penetration Test (SPT) • Shelby tube ~ Piston [] Direct-Push [8J Bulk or grab Blowcount is recorded for driven samplers as the number of blows required to advance sampler 12 inches (or distance noted). See exploration log for hammer weight and drop. A "P" indicates sampler pushed using the weight of the drill rig. ADDITIONAL MATERIAL SYMBOLS SYMBOLS GRAPH LETIER TYPICAL DESCRIPTIONS cc AC CR Cement Concrete Asphalt Concrete Crushed Rock/ Quarry Spalls :-:•:•.•.•.,:,:•:• Topsoil/ f.k.:-•<·=<<· TS Forest Duff/Sod %F AL CA CP cs OS HA MC MD oc PM pp SA TX UC vs NS 55 MS HS NT Measured groundwater level in exploration, well, or piezometer Groundwater observed at time of exploration Perched water observed at time of exploration Measured free product in well or piezometer Graphic Log Contact Distinct contact between soil strata or geologic units Approximate location of soil strata change within a geologic soil unit Material Description Contact Distinct contact between soil strata or geologic units Approximate location of soil strata change within a geologic soil unit Laboratory/ Field Tests Percent fines Atterberg limits Chemical analysis Laboratory compaction test Consolidation test Direct shear Hydrometer analysis Moisture content Moisture content and dry density Organic content Penneablllty or hydraulic conductivity Pocket penetrometer Sieve analysis Triaxial compression Unconfined compression Vane shear Sheen Classification No Visible Sheen Slight Sheen Moderate Sheen Heavy Sheen Not Tested NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions. Descriptions on the logs apply only at !he specific exploralion locations and at the time the explorations were made; they are not warranted to be representative of subsurface conditions at other locations or times. KEY TO EXPLORATION LOGS GEOENGINEERS CJ FIGUREA-1 ' ' ' . ' . ' . i ' ' " • ~ C 0 ~ > • iii Date Excavated: 6/26/2009 Logged By: BHC Equipment: Hand Auger Total Depth (ft) 2.5 SAMPLE fl • ;;: <i C MATERIAL ~ E 0, Q "ji REMARKS • 0 ~ "' ~ 1l .,, DESCRIPTION " 0, I~ u ~ C ,!' ~ C E g-'in ~ 2 0. j;; ~ 0 • ~ e1 u C • • • C 8 0 f-f-(9 (9 u w : SM Brown silty fine to coarse sand with gravel (dense, dry) : --' P" 1 inch IX 1--f- : -2 : X : : 2--C - Refusal on cobbles No groundwater seepage observed No caving observed Notes: See Figure A-1 for explanation of symbols. The depths on the hand auger logs are based on an average of measurements across the hand auger and should be considered accurate to 0.5 foot. Log of Hand Auger HA-1 GEOENGINEERS Q Project: OPLC MP 109 Project Location: Renton, Washington Figure A-2 Project Number: 0894-188-00 Sheet 1 of 1 Date Excavated: 6/26/2009 Logged By: ____ _,B""H"°C,__ ___ _ 0 i I i i i ~ ~ i 'ii ,g C g > .,, w Equipment: ___ _____,H..can=d'-'A--"u"'g~er~---Total Depth (ft) SAMPLE • 0. ;~ 'ii E rn • 0 ,g "' ~ rn 0 ~ C -c ~ 15. ti E~ ~ • ~ •• ~ 0 "')-t') 2 J 4 ,.J_ ____ _J .. • ,: C g " 1l ~ .. ~ C §-'q) a 0 e~ 0 C t')" w SM-ML MATERIAL DESCRIPTION Brown to gray silty fine to co.me sand with gravel to silt with sand and gravel (loose, moist) Gray elastic silt to fat clay with trace sand and occasional gravel (medium stiff, moist) No groundwater seepage observed No caving observed 5.0 ~ REMARKS ~l Oo ~" P = 12 inches P = 40 inches Notes: See Figure A-1 for explanation of symbols. The depths on the hand auger logs are based on an average of measurements across the hand auger and should be considered accurate to 0.5 foot. o Log of Hand Auger HA-2 gl---------------------.---.::..------.....:;;_ ________________________ ~ ! CJ Project: OPLC MP 109 i Geo ENGINEERS r1 J Project Location: Renton, Washington : ~ Project Number: 0894-188-00 Figure A-3 Sheet 1 of 1 Date Excavated: 6/26/2009 Logged By: BHC Equipment: Hand Auger Total Depth (ft) 2.0 SAMPLE 2 • ro 'al" ~ 0. I? C ~ MATERIAL ,!'. 'al" E 0, 1 REMARKS ro 0 ~ C ,!'. "' -' .. DESCRIPTION ~ i 0, i ~ C -; ~ C g-·iii , ~ > 1i ~ E,;; 0. ei 8 C .. • • ro • ~ C 0 UJ 0 .... "'f.-"' "'() UJ <.> SM Brown silty fine to coarse sand with gravel (dense. moist) : -' Probe = 4 inches X : 1--- : -' : .. X : Refusal on cobbles 2 No groundwater seepage observed No caving observed Notes: See Figure A-1 for explanation of symbols. The depths on the hand auger logs are based on an average of measurements across the hand auger and should be considered accurate to 0.5 foot. Log of Hand Auger HA-3 GeoENGINEERS Q Project: OPLC MP 109 Project Location: Renton, Washington Figure A-4 Project Number: 0894-188-00 Sheet 1 of 1 Drive Probe DP-1 Blows per Foot a 10 20 30 40 50 60 70 80 90 100 110 a.a ' ' ' (Loose) ' ' ' ' ' ' 1.0 2.0 ·~ (Refusal on cobble at 1 _5 feet) 3.0 I Drive Probe ----sPT-Equivalent - (Medium dense) 4.0 5.0 Drive probe DP-1 1 . competed adJacent to HA-1. 6.0 7.0 [ t ,!l 8.0 9.0 10.0 11.0 12.0 8 ,§-130 ; ~ o:r-14.0 ~ 0 : 15.0 "-------------------------------- <( ;~~------:::;:::--r---====--_J ~ GeoENGINEERS a DRIVE PROBE EXPLORATION DP-1 FIGUREA-5 Drive Probe DP-2 Blows per Foot 0 10 20 30 40 50 60 70 80 90 100 o.o 1.0 (Loose) 2.0 --t-Drive Probe ----SPT-Equivalent 3.0 4.0 5.0 (Refusal at 4.5 feet) 6.0 (Medium dense) 7.0 ~ ,: a 8.0 " C 9.0 10.0 Drive Probe DP-2 located adjacent to HA-2. 11.0 12.0 13.0 0 ~ "' 14.0 15.0 <( Ol <( ;~~-:;:;:--r----====--=--_J ~ GeoENGINEERS CJ DRIVE PROBE EXPLORATION DP-2 FIGUREA-6 0.0 1.0 2.0 3.0 4.0 5.0 6.0 [ 7.0 .c a .. C 8.0 9.0 10.0 11.0 12.0 0 13.0 ~ ~ ..,- ~ 14.0 0 0 10 20 30 (Loose) Drive Probe DP-3 40 Blows per Foot 50 (Medium dense) 60 70 80 90 100 ~ Drive Probe l --a-SPT-Equivale~ (Refusal at 6.5 feet) ~ <i "' "' ;~~------:;::--r---====---_J ~ GEoENGINEERS CJ DRIVE PROBE EXPLORATION DP-3 15.0 FIGUREA-7 8 ci 0 0 0 "' "' :; "' "' 0 0 ~ <D el .. g .c a " Q Drive Probe DP-4 Blows per Foot 0 10 20 30 40 50 60 70 80 90 100 0.0 ' ' ' (Loose) ' ' ' ' ' ' 1.0 ' ' \. ' ' (Refusal at 1.5 feet). ___ ' ' 2.0 ' ' [_;-Drive Probe ' ~ SPT-Equivalent ' ' ' ' 3.0 ' ' ' 4.0 (Medium dense) 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 GeoENGINEERS a DRIVE PROBE EXPLORATION DP-4 FIGUREA-8 - ·~". / -.. ----~-/; _,-------· I / / / ~---....,___ -------. -------. / ------- ; } / \ I i I I \ ' \ I ' / \ ', \ \ J I i ,/ .--· .,/_..·' I I / / i / / \ -.. _. ,.. .... .... ': ' ) ( I ; \ . \ ' I i I I i I I I 'I \ \ \ } \ I ·, '. ', .. APPENDIX B Slope Stability Analyses ' \ '··---, __ _ RE DM\P,\0\0894188\00\Working\SlopeStabilityfigs.ppt ABA 03/02/1 D 70 "' 30 Slope Assumed satruta~ lO l ~ 10 > J! w 0 -10 .,o -,0 -40 .,o -10 0 IO 20 30 ,o ,0 ao .r.m. 70 80 •• Loose Sily s.na UnM Weight: 120 pct Conesion: 200 psi Phi: 28 • Glacial Soll llnil Waight 1211 pct Cohesion: 1000 psf Phi:D" 100 "" 120 ,,o ''° '"' Distance (feet) Slope Stability-Landslide Milepost 109 Landslide Stabilization Project Olympic Milepost 109 Renton, Washington 11!0 GEOENGINEERS Id Figure B-1 RE DM\P,\0\0894188\00\Working\SlopeStabilityfigs.ppt ABA 03/02/1 0 i' ~ ~ ~ JI w 70 .. 30 20 10 0 -10 -20 -30 Slape Assumed Saturated Rip Rap Unit Waight 150 pc! COhesion: 0 psi Phi: 45 • .. ... , Loose Silty Sand Un~Weight 120 pd Cohesion: 200 psi Pht 28 • Gtadal Soils IJnilWeigllt 130 pd coi.,m:200pst Phi: 34. -00 U...--'-----'---'-----'--_JL-_...L..._......L __ ,..._ _ _,_ _ __. __ _._ _ _,_ __ L-_...J...._-'---,..._-'-_J 130 140 100 .,a 0 10 "' 30 40 ,. ,o 70 80 "' ICO "' Distance (feet) Slope Stability-Proposed Repair Milepost 109 Landslide Stabilization Project Olympic Milepost 109 Renton, Washington GEOENGINEERS /;j Figure B-2 -- -------------------- -.. -. ) / ·~---------- I ' , _,..,/ I I \ I -·· I \ \ ! l i ( '_/ I. I I I ) \ I APPENDIX C Drainage Evaluation Calculations ' . I \ \ \ \ . ' \\\ -.. -__ .---, -·· ( ----______ ,.....- \ / / / RATIONALE METHOD EQUATION -2009 KCSWDM Section 3.2.1 Equation (3-1) Qr= ClrA Equation (3-2) Ct= (C1'A1+C2'A2 ... CnAn)/At "A" Values A1 -Rip Rap A2 -Gravel/ravine A3 -Grass A4 -li.9.ht forest Total Area (At) Qr = peak flow (cfs) for a storm of return frequency r C = estimated runoff coefficient (ratio of rainfall that becomes runoff) Ir = peak rainfall intensity (inches/hour) for a storm of return frequency r A = drainage basin area (acres) At = total Area (acres) A1,2, ... n = areas of land cover types (acres) C 1,2, ... n = runoff coefficients for each area land cover types Sq ft 1585.00 4380.00 5090.00 5484.00 16539.00 Acre 0.04 0.10 0.12 0.13 0.38 C -Cover Coefficient 0.8 0.8 0.25 0.15 C'A 0.03 0.08 0.03 0.02 0.16 =C1 'A1 +C2'A2 ... C4A4) Ct= (C1'A1+C2'A2 ... CnAn)/At = 0.42 Equation (3-3) Ir = (Pr)(ir) Pr100 = Equation (3-4) i100 = (ar)(Tc)exp(-br) a(100 yr) = b(100 yr) = 1100 = (P100)(i100) = Pr = the total precipitation at the project site for the 24-hour storm event for the 100-year, 24-hour precipitation rate from Figure3.2.1.D ir = the unit peak rainfall intensity factor 3.9 inch Tc= time of concentration (minutes) (6.3,;; Tc,;; 100) ac, br = coefficients from Table 3.2.1.B used to adjust the design storm return frequency R For A1 2.61 0.63 3.19 0.82 =i100 T4= Tt= Tc<6.3 Equation (3-1) Q100 = ClrA = with: C = 1100= A= 0.13 1.13 6.30 0.50 0.42 3.19 0.38 minutes minutes minutes Equation (3-5) Tc= T1 + T2+ ... Tn Equation (3-6) Tt = U60V Segment Lroad Lravine Lgrass Lriprap V= kr 1 = sq rt (slope of flowpath) = V1= kr 2= sq rt (slope of flowpath) = V2= kr 3= sq rt (slope of flowpath) = V3= kr 4= sq rt (slope of flowpath) = V3= T1= T2= T3= T1 ,2 .. n = travel time for consecturive flowpath segments with different categories of land cover or flowpath slope Tt = travel time (minutes) L = distance of flow across a given segment (feet) V= average velocity across the land cover = kr .Jso ,J = Square root difference SO=Slope Length in Elev ft/ft Sq Rt slope 142.00 5 0.04 0.187646656 85.00 40 0.47 0.685994341 50.00 10 0.20 0.447213595 50.00 20 0.40 0.632455532 kr • <sq rt (slope of flowpath) > 20.00 road 0.19 3.75 20.00 ravine 0.69 13.72 7.00 short grass 0.45 3.13 10.10 nearly bare ground 0.63 6.39 0.63 minutes 0.10 minutes 0.27 minutes Pipe capacity calculation using Mannings Equation Pipe Length = 30 feet Diameter (inches)= Radius, r, (inches)= Radius, r, (feet)= Depth of Water, d (ft) = Length, L (ft)= phi= phi= A= A= Vol= Vol= Vol= Q=A'u Depth, D= A= U= R=A/wp wp= S= n= 16.00 8.00 0.67 1.33 Depth of Water, d (in) = 30.00 2'arcos(1-(d/r)) 6.28 o. 5 'rA2'(phi-sin(phi)) 1.40 A'L 41.89 f[A3 313.32 gal 7.69 cfs 1.33 1.40 5.51 0.33 4.19 0.01 0.01 16 3452.89 GPM T= wp= 0.00 ft 0.0000 inches ft 4.19ft 50.27 inches Pipe Length = 45 feet Diameter (inches)= Radius, r, (inches)= Radius, r, (feet)= Depth of Water, d (ft) = Length, L (ft)= phi= phi= A= A= Vol= Vol= Vol= Q=A'u Depth, D= A= U= R=Alwp wp= S= n= 16.00 8.00 0.67 1.33 Depth of Water, d (in) = 45.00 2'arcos(1-(d/r)) 6.28 0. 5 'r'2 • (ph i-sin(phi)) 1.40 A'L 62.83 ft'3 469.98 gal 7.69 cfs 1.33 1.40 5.51 0.33 4.19 0.01 0.01 16 T= wp= 3452.89 GPM 0.00 ft o.oo inches 4.19 ft 50.27 inches MP109 Swale Calculations Using Mannings Equation Design Flow O=A'u 0.50 Dn= Sideslope Left Z1 = 2 Sideslope Left Z1= 2 Fr(des)= 8.13 Sideslope Rt. Z2= 2 Sideslope Rt. Z2= 2 Fr(crit)= 1 Bottom Width, b= 1 ft Bottom Width, b= 1 Depth, D= 0.092 ft Dc(trap)= 3.3 Area, A= 0.108928 ft'2 A= 25 Velocity; u= 4.57 fps Qdesign= 0 R=Aiwp 0.08 Qcrit= 189 Wetted perimeter; wp= 1.41 ft TopWidth, T(des)= 1.368 Slope of swale; S= 0.35 Topwidth, T(crit)= 14.2 Mannings Coefficient; n= 0.035 Top of Swale; T = 1.368 ft Dc(rect)= 0.20 Bid= 10.87 Maximum Flow with 6-inches of Freeboard O=A'u 11.5 Dn= Sideslope Left Z1 = 2 Sideslope Left Z1= 2 Fr(des)= 12.35 Sideslope Rt. Z2= 2 Sideslope Rt. Z2= 2 Fr(crit)= 1 Bottom Width, b= 1 ft Bottom Width, b= 1 Depth, D= 0.5 ft Dc(trap)= 3.3 Area, A= 1 ft'2 A= 25 Velocity; u= 11.51 fps Qdesign= 12 R=Aiwp 0.31 Qcrit= 189 Wetted perimeter; wp= 3.24 ft TopWidth, T(des)= 3 Slope of swale; S= 0.35 Topwidth, T(crit)= 14.2 Mannings Coefficient; n= 0.035 Top of Swale; T = 3 ft Dc(rect)= 1.60 Bid= 2 Page 1 2009 Surface Water Design Manual KING COUNTY, WASHINGTON. SURFACE WATER DESIGN MANUAL KING COUNTY, WASHINGTON SURFACE WATER DESIGN MANUAL REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET l/912009 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER • 'ID PROJECT ENGINEER Project Owner e2'11mpic V,e,• I •!lr C.o Phone 8 5,...,-\-"-, -£/l5"-j$(-,;1.C1.7.0 Address Z.~-19 L,,-,n Av<--;,W g,,.-b" wA '1@cs 1 Project Engineer ;,'r,a.<.J ,_ ". -~ ~.;,v.\~if Company 6. S:P S"t)' o <'.ctr ;o Phone ~:).'.~ -ill# I -I -"'4 "l Part 3 TYPE OF PERMIT APPLICATION CJ Landuse Services Subdivison I Short Subd_ I UPD CJ Building Services MIF / Commerical / SFR llt"c1eanng and Grading CJ Right-of-Way Use Gl Other G.~t,H"-\ Cor'.~~-,<.~on f'e:,,-,:~ Part 5 PLAN AND REPORT INFORMATION Technical lnfonnatlon Report Type of Drainage Review Full / <Jarg~ / (circle): Large Site Date (include revision ft' '. ·1 \' ,:. ,r", J.; ._.,\() ' dates): Date of Final: Part 6 ADJUSTMENT APPROVALS Part 2 PROJECT LOCATION AND DESCRIPTION Project Name 01,v, p•c f, f-' "~ l."l,.c;;.liti;;'·-k.'c,'·,~:11, DOES Permit# --------- Location Township 2 ;it~ Range 5 E IJ.f'-\ _ Section I lg Site Address r ~ r+ Part 4 OTHER REVIEWS AND PERMITS CJ DFW HPA CJ Shoreline CJ COE 404 Management CJ CJ Structural DOE Dam Safely RockeryNault/ __ CJ FEMA Floodplain CJ ESA Section 7 CJ COE Wetlands Bother (',;~-,LJ",\ArW-~ :'_,_. ,,,p\'.'",_,,, Site Improvement Plan (Engr. Plans) Type (circle one): Full I Modified , Smaiisije~ I Date (include revision .. . , _ ., '!i/010 ' dates): Date of Final: Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket Description: (include conditions in TIR Section 2) 1'I / J'. Date of Annroval: 2009 Surface Water Design Manual 1/9/2009 I KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: :_;;;;y No Describe: ~ i :± s.; \j.)\ \ I '.>t"-r,-,,or-., J1.i,r e.::: , .. cl,' { .·•• ,;.i,·-. ·,£~,='i-.,.,.., -, _,,.,;, . ,,:... : ~.I, .t ' Start Date: :J uLI ~010 -£,, -H,g, , . ~, '-r-..J:+w\(..4, '{\()i '\,r ... 1'" Completion Date: ..J0I, ·,_.:) l \ .... e_,!lr • ' Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan:------------- Special District Overlays:----------------------- Drainage Basin:-,----,------------ Stormwater Requirements: Part 9 ONSITE AND ADJACENT SENSITIVE AREAS 13 River/Straam ~ Steep Slope __ -.. -... c:~""-'i ,,~---- 0 Lake l:a Erosion Hazard ------- ~ Wetlands µl Landslide Hazard _;;;',__,a:.-.:..· ... '. ---'-.....;.r""'·~t-" D Closed Depression O Coal Mine Hazard------- 0 Floodplain D Seismic Hazard -------- 0 Other D Habitat Protection-------0 _________ _ Part 10 SOILS Soil Type Slopes Erosion Potential A I c\er ·,-"· · .i Q -Lio· .-;Jo I ""° r:.. ' . ' -o -~o 0 /o l"V1 oc.\-\.\ ;, "' u 0 High Groundwater Table (within 5 feet) D Sole Source Aquifer ~ Other .::.1 r : J ·.i. _.:,,..-1 ,r D Seeps/Springs 0 Additional Sheets Attached 2009 Surface Water Design Manual 1/9/2009 2 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAlNAGE DESIGN LIMITATIONS REFERENCE LIMITATION/ SITE CONSTRAINT D Core 2 -Offsite Ana~§i§ "'" \ ~or. c. . ' ' _;;_ "T ~ ,-. ' -, -:-, ~ "' D lan1itive/Critigl 6Cll!lli ~r". P~ It-.'" i~IP t; ~ :"",-.. ,\-!tt·:r_. \.:::.; D ~1;;e.e "1iA 1 D Qlb1r D D Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summarv Sheet oer Threshold Dischame Area) Thrnhold Discharge Area: D,<.cho.rj <t-ore.o-, . ., o.ppr.., .... ,.,._,,-1.,_1,1 :,. ~ (0..{..i{: ~ (name or descriDtion) <>""""-<.wo. \,. (~'!.<:., '5;,.,u_~ ~ • .( ~ '}' Core Requirements (all 8 apply) Discharae at Natural Location Number of Natural Dischara@ Locations: I Offsite Analysis Level: (JJ/213 dated: J:ii ,., -~~IZ , 2=>] Flow Control NIA Level: 1 / 2 / 3 or Exemption Number (incl. facililv summarv sheet) Small Site BMPs Conveyance System N/1',, Spill containment located at: Erosion and Sediment Control ESC SHe Supervisor: fu ro ~ K,::. lb 'ou r--( Contact Phone: 2..0 i.. -i. -i. 'l. -S <, ~ 3 After Hours Phone: "2.o 11 . ·;," 'I -St, 'IS Maintenance and Operation Responsibillty: i Privatei / Public If Private, Maintenance Loa Reauired: ~ / No Financial Guarantees and Provided: Yes I@ Liabilitv Water Quallty Type: Basic / Sens. Lake / Enhanced Basicm / Bog (include facillty summary sheet) or Exemption No. Land..,._...,. Manaaement Plan: Yes / ctJnJ Soaclal R11<1ulrements (as annllcable) Area Specific Drainage Type: CDA / SDO /MOP/ BP/ LMP / Shared Fae. I None R""'uirements Name: Floodplain/Floodway Delineation Type: Major I Minor I Exemption I~ 100-year Base Flood Elevation (or range): Datum: Flood Protection Facilities Describe: No I\ e.. Source Control Describe landuse: l\b" e. (comm.flndustrial landuse) Describe any structural controls: 2009 Surface Water Design Manual 1/9/2009 3 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Oil Control High-use Srte: Yes / t:!g,I Treatment BMP: Maintenance Agreement: Yes 1§ with whom? Other Dralnaae Structures Describe: \)r .. 1 ·, r-..o. ~ L f• f C ~ ,,j, ,-, , . ., ~. i :!. ,,, . ., e. ' • I ' -·I ... J 111"11·~ , ~ , 0,: r . f ~ ;. ' ' - Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION ~ AFTER CONSTRUCTION ISr Clearing Limits Stabilize Exposed Surfaces GY Cover Measures l:J"Remove and Restore Temporary ESC Facilities C3" Perimeter Protection C3"' Clean and Remove All Silt and Debris, Ensure ut'rraffic Area Stabilization Operation of Permanent Facilities Gr Sediment Retention Gr Flag Limits of SAO and open space 13'" Surface Water Collection preservation areas CJ Other Cl Dewatering Control 13" Dust Control 1:3' Flow Control Part 14 STORMWATER FACILITY DESCRIPTIONS /Note: Include Facililv Summarv and Sketch! Flow Control T criotion Water Qualilv T :Ution Cl Detention CJ Biofiltration CJ Infiltration CJ Wetpool CJ Regional Facility Cl Media Filtration 0 Shared Facility CJ Oil Control cg Flow Control l'."101.., c\«.</, fa\_,,.. CJ Spill Control BMPs ti_ Flow Control BMPs ~ Other G~d, x.h 1., Flo~) d '~" pio +, ,- (2.1 Other .:. •. :_ .. -t~ l.£ 2009 Surface Water Design Manual 1/9/2009 4 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS r·<{'. Part 16 STRUCTURAL ANALYSIS D Drainage Easement D Cast in Place Vault D Covenant D Retaining Wall D Native Growth Protection Covenant D Rockery> 4' High D Tract ~ Structural on Steep Slope D Other D Other Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual stte 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 5 1/9/2009 ------------------------ , ./ ,-- I / \ I I /,1 . I I / / ( . / / r·--..........._ i { . ....__. -----~· . ._______ __ ' · .... _ ------- -----..... ----., \ ' '·-'· ) / I ( ----- .------. ( . -. / -. l ... , ...... / \ APPENDIX D Report Limitations and Guidelines for Use \ / / I / / // I• .. ! / l \ \\ \ '· ,.\, \ ! ' \ . -------- ''• i . / --- \ ·· ........... ___ .,.,--------/ - Geologic and Geotechnical Design Report Renton, Washington APPENDIXD REPORT LIMITATIONS AND GUIDELINES FOR USE 1 This appendix provides information to help you manage your risks with respect to the use of this report. Geotechnical Services are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of Olympic Pipe line Company (Olympic) and their authorized agents. This report may be made available to Olympie's contractors and agents for review. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each geotechnical or geologic study is unique. each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of our Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with the Client and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Geotechnlcal Engineering or Geologic Report Is Based on a Unique Set of Project- Specific Factors This report has been prepared for the proposed landslide stabilization project at Olympic MP-109, in Renton, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: 1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences: www.asfe org. GEOENGINEER~ March 26, 2010 I Page 0-1 Ale No. 0894-188-00 Geologic and Geotechnlcal Design Report Renton, Washington • the function of the proposed structure; • elevation, configuration, location, orientation or weight of the proposed structure; • composition of the design team; or • project ownership. If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. Subsurface Conditions Can Change This geotechnical or geologic report is t>ased on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. Most Geotechnical and Geologic Findings are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Geotechnical Engineering Report Recommendations are not Final Do not over-rely on the preliminary construction recommendations included in this report. These recommendations are not final, because they were developed principally from GeoEngineers' professional judgment and opinion. GeoEngineers' recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for this report's recommendations if we do not perform construction observation. Sufficient monitoring, testing and consultation by GeoEngineers should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities are completed in accordance with our recommendations. Retaining Geo Engineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. A Geotechnlcal Engineering or Geologic Report Could be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. You could lower that risk by having Geo Engineers confer with appropriate members of the design Page D-2 March 26, 2010 GeoEngineeis, Inc. FIie No. 0894-188-00 - Geologic and Geotechnical Design Report Renton, Washington team after submitting the report. Also retain GeoEngineers to review pertinent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or geologic report. Reduce that risk by having Geo Engineers participate in pre-bid and preconstruction conferences, and by providing construction observation. Do Not Redraw The Exploration Logs Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors A Complete Report And Guidance Some owners and design professionals believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might an owner be in a position to give contractors the best information available, while requiring them to at least share the financial responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be included in your project budget and schedule. Contractors Are Responsible For Site Safety On Their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and to adjacent properties. Read These Provisions Closely Some clients, design professionals and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory "limitations" provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these "Report Limitations and Guidelines for Use" apply to your project or site. Geotechnical, Geologic And Environmental Reports Should Not Be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental GEO ENGINEER~ March 26, 2010 I Page 0-3 FlleNo. 0894-188-00 Geologic and Geotechnlcal Oestgn Report Renton, Washington findings, conclusions or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. Biological Pollutants GeoEngineers' Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants and no conclusions or inferences should be drawn regarding Biological Pollutants, as they may relate to this project. The term "Biological Pollutants" includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. If Client desires these specialized services, they should be obtained from a consultant who offers services in this specialized field. Page D-4 March 26, 2010 GeoEngjneers, Inc. Ale No. 0894-188-00