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Kinkade Crossing TIR II Comments
TECHNICAL INFORMATION REPORT FOR KINKADE CROSSING Prepared for: Taylor Development 15 Lake Bellevue Drive, Suite 102 Bellevue, WA 98005 Prepared by: ESM Consulting Engineers, LLC 33400 8th Avenue S, Suite 205 Federal Way, WA 98003 May 25, 2016 Job No. 994-001-015 Approved By: City of Renton Date \\esm8\engr\esm-jobs\994\001\015\document\kinkadecrossingtir-2016-05-24.docx 1 TABLE OF CONTENTS 1. PROJECT OVERVIEW ................................................................................................................................................................................ 1-1 2. CONDITIONS AND REQUIREMENTS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 3. OFF-SITE ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 4. FLOW CONTROL & WATER QUALITY FACILITY ANALYSIS AND DESIGN .............................4-1 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN .............................................................................................. 5-1 6. SPECIAL REPORTS AND STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 7. OTHER PERMITS ............................................................................................................................................................................................. 7-1 8. CSWPPP ANALYSIS AND DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ...9-1 10. OPERATIONS AND MAINTENANCE MANUAL ............................................................................................................ 10-1 LIST OF FIGURES 1.1 Vicinity Map 1.2 Existing Site Conditions 1.3 Proposed Site Conditions 1.4 Soils Map 3.1 KCGIS Parcel Reports/Environmental Hazards 3.2 Drainage Complaint Map 3.3 Site Topography 3.4 Offsite Analysis Downstream Flowpath 3.5 Offsite Analysis Drainage System Table 4.1 Pond Tributary Area 2 1.PROJECT OVERVIEW The proposed Kinkade Crossing project is a 17-lot plat located southwest of the intersection of 116th Ave SE and SE Petrovitsky Road in the City of Renton, WA. The plat incorporates one parcel numbered 322305-9303, which is zoned R-8. See Figure 1.1 for the Vicinity Map. The existing site consists of 1 single-family dwelling with associated driveway and several detached sheds near the dwelling. The existing site is relatively flat (mean slope of 5.5%, less than 10% max slopes on site) with a slope from the southwest to the northeast corners of the project site. The pervious portions of the parcel are generally pastured. See Figure 1.2 for the Existing Site Conditions. The proposed 3.64 acre project site consists of 17 residential lots for single-family dwelling units and the associated road network. The lots are proposed to be 5,000 square feet minimum and will be served by Road A, going north/south, Alley A on the north side, going east/west and an extension to SE 177th PL and Road B to 116th Ave SE also going east/west. See Figure 1.3 for the Proposed Site Conditions. Stormwater detention and water quality treatment will be provided in a combined detention/water quality pond located in Tract B, at the northeast corner of the site. The combined stormwater facility will discharge east, towards the natural location, in a piped system to connect to the existing stormwater conveyance system in 116th Ave SE and ultimately flow east along SE Petrovitsky Road and enter Big Soos Creek. See Section 3 for the Level 1 Downstream Analysis. According to the Geotechnical Engineering Report (GER)by The Riley Group, Inc. (RGI), on July 08, 2015 and attached in Section 6, the soils onsite include loose to very dense silty sand with gravel. See Figure 1.4 for the Soils Map. Based on the City of Renton’s Flow Control Application Map, the project site is in the Flow Control Duration Standard (Forested Conditions, Level 2) area. The project will be subject to Full Drainage Review per the City of Renton 2009 Surface Water Design Manual Amendments and the 2009 King County Surface Water Design Manual (2009 KCSWDM). The City of Renton 2009 Surface Water Design Manual Amendment and the 2009 KCSWDM will collectively be referred to as the “2009 Surface Water Design Manual”. 3 Figure 1.1 Vicinity Map Project Name: Kinkade Crossing Project Address: 17709 116th Ave SE, Renton, WA 98058 Lat/Long: 47.444184, -122.187074 S-T-R: 32-23N-5E Data Source: BING Maps, City of RentonJun 22, 2015 11:39PM patrick I:\ESM-JOBS\994\001\015\gis\VIC-001.mxd^_ ÜN.T.S. Vicinity Map ® 0 1,500750 1 inch = 1,500 feet 4 Figure 1.2 Existing Site Conditions 5 Figure 1.3 Proposed Site Conditions 6 Figure 1.4 Soils Map Soil Map—King County Area, Washington (Kinkade Crossing) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/20/2015 Page 1 of 3525465052547405254830525492052550105255100525465052547405254830525492052550105255100561080561170561260561350561440561530561620561710561800561890 561080 561170 561260 561350 561440 561530 561620 561710 561800 561890 47° 26' 48'' N 122° 11' 24'' W47° 26' 48'' N122° 10' 44'' W47° 26' 31'' N 122° 11' 24'' W47° 26' 31'' N 122° 10' 44'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0150300 600 900 Feet 050100 200 300 Meters Map Scale: 1:3,820 if printed on A landscape (11" x 8.5") sheet. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 10, Sep 30, 2014 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 31, 2013—Jul 15, 2014 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington (Kinkade Crossing) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/20/2015 Page 2 of 3 Map Unit Legend King County Area, Washington (WA633) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AgB Alderwood gravelly sandy loam, 0 to 8 percent slopes 41.1 58.2% AgC Alderwood gravelly sandy loam, 8 to 15 percent slopes 29.6 41.8% Totals for Area of Interest 70.7 100.0% Soil Map—King County Area, Washington Kinkade Crossing Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/20/2015 Page 3 of 3 7 2. CONDITIONS AND REQUIREMENTS SUMMARY Review of the 8 Core Requirements and 6 Special Requirements This section describes how the project will meet the 2009 Surface Water Design Manual’s Core and Special Requirements. Core Requirement No. 1 Discharge at the Natural Location In the existing conditions, the site drains to the northeast, however the flows converge about 200 feet downstream, at the intersection of SE Petrovitsky Road and 116th Ave SE. In the proposed condition, the combined detention/water quality pond will discharge east on 116th Ave SE, which is the natural discharge location for the project site. Core Requirement No. 2 Off-site Analysis A Level 1 Downstream Analysis was performed by ESM on June 22, 2015. See Section 3 for the offsite analysis. Core Requirement No. 3 Flow Control The proposed project generates a larger developed peak flow than the pre-developed peak flow, which is more than 0.1 cfs, the proposed project will have to meet the flow control requirements. Based on the City of Renton’s Flow Control Application Map, the project site is in the Flow Control Duration Standard (Forested Conditions, Level 2) area. See Section 4 for flow control analysis and calculations. Core Requirement No. 4 Conveyance System The stormwater drainage conveyance system has been sized to convey the 25 year design storm event and to contain the 100 year design storm event. See Section 5 for conveyance calculations. Core Requirement No. 5 Erosion and Sediment Control The proposed project includes clearing and grading for the 17 new single-family units, open space tract, associated roadways, and pond area. Erosion and sediment controls will be provided to prevent, to the maximum extent possible, the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties. The Temporary Erosion and Sedimentation Control (TESC) Plan is shown on sheets GR-01 through GR-03 and described in Section 8. Core Requirement No. 6 Maintenance and Operations The Operations and Maintenance Manual is included in Section 10. Core Requirement No. 7 Financial Guarantees and Liability All drainage facilities constructed or modified for projects will comply with the financial guarantee requirements as provided in the City of Renton Bond Quantities Worksheet, which is included in Section 9. Core Requirement No. 8 Water Quality The proposed project produces more than 5,000 square feet of pollution generating impervious area and is required to meet the water quality requirements. According to King County iMap, the project site requires Basic Water Quality. The site does not meet the requirements for enhanced treatment in the 2009 Surface Water Design Manual. Treatment for the pollution generating surfaces will be provided by a combined detention/water quality pond. See Section 4 for more information. 8 Special Requirement No. 1 Other Adopted Area-Specific Requirements There are no master drainage plans, basin plans, salmon conservation plans, stormwater compliance plans, flood hazard reduction plan updates, or shared facility drainage plans for this project. Special Requirement No. 1 does not apply. Special Requirement No. 2 Flood Hazard Area Delineation There is no 100-year flood plain associated with a large body of water (i.e. lake or stream) on the site or adjacent to the site. Special Requirement No. 2 does not apply. Special Requirement No. 3 Flood Protection Facilities The project lies outside any pre-defined flood plain. Special Requirement No. 3 does not apply. Special Requirement No. 4 Source Control The project is a residential subdivision and is not subject to this requirement. Special Requirement No. 4 does not apply. Special Requirement No. 5 Oil Control The project does not have a “high-use site characteristic” and is not a redevelopment of a high-use site. Special Requirement No. 5 does not apply. Special Requirement No. 6 Aquifer Protection Area According to the “Groundwater Protection Areas in the City of Renton” map, the project site is not in an Aquifer Protection Area. Special Requirement No. 6 does not apply. 9 3.OFF-SITE ANALYSIS Task 1: Study Area Definition and Maps Figure 1.2 shows the existing site conditions. Figure 3.4 shows the extent of offsite analysis and the downstream flow path from the site. Task 2: Resource Review ·Flow Control Map According to the City of Renton Flow Control Application Map, the site is a Flow Control Duration Standard (Forested Conditions) area. ·Soil Survey Map According to the City of Renton Soil Survey prepared by City of Renton Public Works Department on 01/09/2014, the geologic map of the area indicates that the soil type on the project site is AgB: ALDERWOOD GRAVELLY SANDY LOAM, 0 TO 6 PERCENT SLOPES. The GER indicates that the soils onsite include loose to very dense silty sand with gravel. Further details and descriptions can be found in the GER attached in Section 6. ·King County iMap According to the King County GIS Viewer (iMap), the project is NOT in any of the following areas: o Streams & 100 year floodplains o Erosion Hazard Areas o Seismic Hazard Areas o Landslide Hazard Areas o Coal Mine Hazard Areas o Wetlands ·City of Renton 2009 Surface Water Design Manual Amendments According to Reference 11-B in the City of Renton 2009 Surface Water Design Manual Amendments, the project is NOT in any of the following areas: o Aquifer Protection Areas o Groundwater Protection Areas ·Road Drainage Problems None noted ·Wetlands Inventory There are no recorded wetlands on or near the site according to iMap and the 1990 King County Wetlands Inventory Notebooks. ·Migrating River Study None noted ·Downstream Drainage Complaints 10 According to the information available on iMap, there have been no downstream drainage complaints in the study area within the last 10 years. 11 Figure 3.1 KCGIS Parcel Report/Environmental Hazards 8/21/2015 King County Districts and Development Conditions for parcel number 3223059303 http://www5.kingcounty.gov/KCGISReports/dd_report_print.aspx?PIN=3223059303 1/1 King County Districts and Development Conditions for parcel 3223059303 Parcel number 3223059303 Address Not Available Jurisdiction Renton Zipcode 98058 Kroll Map page 604 Thomas Guide page 656 and 686 Drainage Basin Soos Creek Watershed Duwamish Green River WRIA DuwamishGreen (9) PLSS NE 32 23 5 Latitude 47.44465 Longitude 122.18632 Electoral Districts Voting district RNT 110539 King County Council district District 5, Dave Upthegrove (206) 4771005 Congressional district 9 Legislative district 11 School district Renton #403 Seattle school board district does not apply (not in Seattle) District Court electoral district Southeast Fire district does not apply Water district does not apply Sewer district does not apply Water & Sewer district Soos Creek Water & Sewer District Parks & Recreation district does not apply Hospital district Public Hospital District No. 1 Rural library district Rural King County Library System King County planning and critical areas designations King County zoning NA, check with jurisdiction Development conditions None Comprehensive Plan um Urban Growth Area Urban Community Service Area does not apply Community Planning Area Soos Creek Coal mine hazards?None mapped Erosion hazards?None mapped Landslide hazards?None mapped Seismic hazards?None mapped Potential annexation area does not apply Rural town?No Water service planning area does not apply Roads MPS zone 341 Transportation Concurrency Management does not apply Forest Production district?No Agricultural Production district?No Critical aquifer recharge area?None mapped 100year flood plain?None mapped Wetlands at this parcel?None mapped Within the Tacoma Smelter Plume?20.1 ppm to 40.0 ppm Estimated Arsenic Concentration in Soil This report was generated on 8/21/2015 8:25:01 AM Contact us at giscenter@kingcounty.gov. © 2015 King County 12 Task 3: Field Inspection (Level 1 Inspection) A Level 1 Downstream Analysis was completed by ESM Consulting Engineers in the afternoon on June 22, 2015, when it was partly cloudy and 76°F. During the inspection it was found that the project site slopes from the southwest to the northeast, with no offsite areas observed to drain to the property. There are approximately 5 residential lots at the southwest corner of the property that appear to be higher than the project site, that are bordered by fences and dense landscaping. These lots do not appear to drain to the project site but to 114th Place SE. Typical culverts were 12” CMP along the east frontage and constricted from vegetation and litter. The edge of the asphalt pavement of 116th Ave SE has eroded into the roadside ditch in some places along the east frontage of the project site. Task 4: Drainage Description and Problem Descriptions According to iMap, the project site is in the Soos Creek (King County WRIA number: 9) basin. Big Soos Creek is located to the north and east of the project site. The project site’s high point is the south-west corner which causes the existing site to flow to the north and east boundaries. All flows on the east boundary flow into a roadside ditch and enter the storm drainage system on 116th Ave SE. All flows on the north boundary enter the storm drainage system on SE Petrovitsky Road. Some flows at the north-east corner of the project site sheet flow onto the parcel adjacent to the project at the corner of 116th Ave SE and SE Petrovitsky Road. All of these flows converge in the storm drainage system on SE Petrovitsky Road and flow along SE Petrovitsky Rd in a piped catch basin system for about 1300 feet until they are discharged into Big Soos Creek. Task 5: Mitigation of Existing or Potential Problems All runoff from the site will be collected in a piped storm system and directed to the proposed combined detention/water quality pond. From there, runoff will be discharged at the Flow Control Duration Standard (Forested Conditions) into the existing storm drainage system in 116th Ave SE. 13 Figure 3.2 Drainage Complaint Map 14 15 Figure 3.3 Site Topography 16 17 Figure 3.4 Offsite Analysis Downstream Flowpath 18 19 Figure 3.5 Offsite Analysis Drainage System Table 20 Figure 3.6 Picture from Point #1 Looking north along 116th Ave SE 21 Figure 3.7 Picture from Point #2 Looking north along 116th Ave SE The 12” CMP culvert was almost completely covered with vegetation. 22 Figure 3.8 Picture from Point #3 Looking north along 116th Ave SE The 12” CMP culvert was covered with vegetation under the driveway. 23 Figure 3.9 Picture from Point #4 Looking north along 116th Ave SE Flows from the ditch enter the culvert and are piped into the storm drain system from this location. The culvert was covered with litter and vegetation. 24 Figure 3.10 Picture from Point #5 Looking west along SE 176th St 25 Figure 3.11 Picture from Point #6 Looking east along SE 176th St (Petrovitsky) The manhole cover shown in the crosswalk is estimated to be the point of convergence between the 116th Ave SE and SE 176th St storm drains. From there it’s piped to Big Soos Creek. 26 Figure 3.12 Picture from Point #7 Looking east along SE 176th St (Petrovitsky) The estimated discharge location of the project site’s storm water, approximately 1300 feet downstream of the project site. 27 4.FLOW CONTROL & WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Existing Site Hydrology The existing site consists of 1 single-family dwelling with associated driveway and several detached sheds near the dwelling. The existing site is relatively flat (mean slope of 5.5%, less than 10% max slopes on site) with a slope from the southwest to the northeast corners of the project site. The pervious portions of the parcel are generally pastured. According to the GER by RGI the soils onsite include loose to very dense silty sand with gravel. See Figure 1.4 for the Soils Map. This report shows that the site is generally underlain with Till soils, which are incapable of infiltration. Therefore Till soils are used in the KCRTS model, with the predeveloped area being modeled as Till Forest. Due to the existing site slope, the site will flow toward the northeast corner of the property. These flows converge about 200 feet downstream of the project site at the intersection of SE Petrovitsky Road and 116th Ave SE. The predeveloped basin for the project site also includes the frontage improvements. This area will be improved with a new sidewalk including curb and gutter. TABLE 4.1 Pre-Developed Tributary Area SUBBASIN TOTAL AREA (Ac) TILL FOREST (Ac) IMPERVIOUS (Ac) Onsite Basin 3.50 3.50 0.00 Bypass Basin 0.14 0.14 0.00 Offsite Basin 0.08 0.01 0.07 TOTAL 3.72 3.67 0.07 4.2 Developed Site Hydrology The project will create 17 single family lots with associated roadway, sidewalk, driveways, roof areas, landscaped yards, and a combined detention/water quality pond adjacent to an open space tract. All 17 residence lots will have new single-family dwelling units. A portion of the frontage improvement area will bypass the pond and be treated as bypass area. For more information, see Table 4.3 below and Figure 4.1. The maximum impervious surface area allowed by the City of Renton Zoning Code 4-2- 110A for R-8 zoned lots is 65%. However, the site will utilize Flow Control BMP C2.9 Reduced Impervious Surface Credit, and reduce on-site allowable impervious area by 10%. Therefore, building rooftops and impervious areas (driveway, porch, patios) are modeled as 55% impervious. 28 The combined detention/water quality pond is located in the northeastern corner of the site. The combined detention/water quality pond will discharge to the east into the existing 116th Ave SE system, which is the site’s natural discharge location. TABLE 4.2 Developed Pond Detained Area SUBBASIN TOTAL AREA (Ac) TILL GRASS (Ac) IMPERVIOUS (Ac) Onsite Basin 3.50 1.48 2.02 Offsite Basin 0.08 0.01 0.07 TOTAL 3.58 1.49 2.09 TABLE 4.3 Developed Bypass Area SUBBASIN TOTAL AREA (Ac) TILL GRASS (Ac) IMPERVIOUS (Ac) Bypass Basin 0.14 0.04 0.11 TOTAL 0.14 0.04 0.11 See Figure 4.1 for a visual representation of the Developed Tributary Area. 4.3 Performance Standards Performance Standards for flow control design use the KCRTS Methodology with hourly time steps as described in Section 4.4 below. Runoff files for the existing, proposed, and bypass conditions were created using the historic KCRTS time series data sets for the SeaTac Rainfall Region with a Correction Factor of 1.0. The site requires basic water quality treatment. Water quality will be satisfied with a wetpond, which will be located in the combined detention/water quality pond. 4.4 Flow Control System The proposed project generates a larger developed peak flow than the pre-developed peak flow, which is more than 0.1 cfs, the proposed project will have to meet the flow control requirements. The pond was sized per the requirements in the 2009 Surface Water Design Manual. Per the City of Renton’s Flow Control Application Map, the project site is in the Flow Control Duration Standard (Forested Conditions, Level 2) area. This standard requires the site to match the durations of high flows at their predevelopment levels for all flows from one-half of the 2 year peak flow up to the 50 year peak flow. The project will also match developed peak discharge rates to predeveloped peak discharge rates for the 2 and 10 year return periods. The offsite flows being routed through the pond are not subject to flow control, therefore the offsite flows will be added to the predeveloped and developed flows. PreDevFT = PreDev (Onsite + Bypass) + Offsite (Flow Through) 29 DevFT = Dev (Onsite) + Offsite (Flow Through) The target flows are calculated as follows: 50% 2 year: 50% of the 2 year from PreDev (Onsite) + Offsite 2 year 50 year: PreDev 50 year + Offsite 50 year The pond’s inflow will be modeled using the DevFT time series and the pond’s outflow will be the RDout time series. This RDout time series plus the Bypass time series will match the Flow Control Duration Standard (Forested Conditions, Level 2) at the Point of Compliance 200 feet downstream of the project site. KCRTS v6.0 was used to design the proposed pond. Procedures and design criteria specified in the 2009 Surface Water Design Manual were followed for the hydrologic and hydraulic modeling. The KCRTS pond sizing output is included at the end of this section. The KCRTS output models the required detention volume as 47,600 cubic feet of storage, with 8 feet of detention. The proposed pond provides 50,135 cubic feet of storage, which results in a 5% factor of safety. An outflow control structure and an emergency overflow structure have been provided on the plans. They are estimated to comply with Section 5.3.1 and Section 5.3.4 of the 2009 KCSWDM. 4.5 Water Quality Facility The proposed project produces more than 5,000 square feet of pollution generating impervious area and is required to meet core requirement #8 for water quality. The proposed water quality pond for Kinkade Crossing will use the 2009 Surface Water Design Manual guidance for Basic Menu wetpond(s) that would be sized to a VB/VR ratio of 3.0, which will treat approximately 95 percent of all runoff. A VB/VR = 3 is calculated by dividing the wetpond volume (VB) by the volume of runoff (VR) from the mean annual storm. The sizing of wetponds is accomplished by determining the acreage of pervious and impervious land. Runoff volumes from pervious and impervious areas were determined by multiplying the acreage of each category by the mean annual storm (0.47 inches). Runoff factors of 0.25 for till grass areas, 0.10 for till forest areas and 0.90 for impervious areas were utilized. The sum of these values is the total runoff volume (VR). The required basin volume or the volume of the wetpond is determined by multiplying the VR by 3.0. VR_Till_Grass = 1.28 Ac (Table 4.2) x 0.47 in. x 0.25/12 = 0.0125 Acre - feet VR_Impervious = 2.30 Ac (Table 4.2) x 0.47 in x 0.90/12 = 0.0811 Acre - feet Total runoff volume VR = VR_Till_Grass + VR_Impervious = 0.0936 Acre - feet Total basin volume VB = 0.0936 x 3 = 0.2798 Acre - feet = 12,233 cubic feet Wetpond Volume provided = 12,664 cubic feet The bypass area will not be able to be treated due to topography. The bypass area is less than 5,000 square feet of Non-Pollution Generating Impervious Surface and 30 therefore will not require treatment in accordance with Core Requirement #8 of the 2009 Surface Water Design Manual. Additionally, the wetpond will not have a till liner, as the existing soils are impermeable till. 30 Figure 4.1 Pond Tributary Area (GFGTCN9C[9#VJ#XG55WKVG014&+%4+&)'..%-+0-#&'%4155+0)(+) AREAS SUMMARY IMPERVIOUS PGIS PERVIOUS TOTAL AREA 1.75 0.46 1.52 DEVELOPED AREA TO POND 1.57 0.46 1.48 POND BYPASS AREA 0.11 0.00 0.04 OFFSITE AREA TO POND 0.07 0.00 0.01 Kinkade Crossing KCRTS Input: KCRTS Program...File Directory: C:\KC_SWDM\KC_DATA\ [C] CREATE a new Time Series ST 3.64 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.00 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0.00 0.00 0.000000 Impervious PreDev.tsf F 1.00000 T [C] CREATE a new Time Series ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 1.48 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 2.02 0.00 0.000000 Impervious Dev.tsf F 1.00000 T [C] CREATE a new Time Series ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.01 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0.07 0.00 0.000000 Impervious OffsiteFT.tsf F 1.00000 T [C] CREATE a new Time Series ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.04 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0.11 0.00 0.000000 Impervious Bypass.tsf F 1.00000 T [A] ADD Time Series PreDevFT.tsf 2 offsiteft.tsf 1.00000 0.00000 predev.tsf 1.00000 0.00000 [A] ADD Time Series DevFT.tsf 2 offsiteft.tsf 1.00000 0.00000 dev.tsf 1.00000 0.00000 [T] Enter the Analysis TOOLS Module [P] Compute PEAKS and Flow Frequencies predevft.tsf PreDevFT.pks [P] Compute PEAKS and Flow Frequencies devft.tsf DevFT.pks [D] Compute Flow DURATION and Exceedence predevft.tsf Target.dur F F 36 0.640000E-02 0.505000E-01 [R] RETURN to Previous Menu [F] Size a Retention/Detention FACILITY Manual Design Pond.rdf 5 Route Time Series 0 Return to Main Menu [T] Enter the Analysis TOOLS Module [P] Compute PEAKS and Flow Frequencies bypass.tsf Bypass.pks [R] RETURN to Previous Menu [X] eXit KCRTS Program PreDevFT Peaks: Flow Frequency Analysis LogPearson III Coefficients Time Series File:predevft.tsf Mean= -0.999 StdDev= 0.220 Project Location:Sea-Tac Skew= -0.121 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.124 16 2/16/49 22:00 0.269 1 89.50 0.989 0.239 3 3/03/50 16:00 0.243 2 32.13 0.969 0.243 2 2/09/51 18:00 0.239 3 19.58 0.949 0.083 33 1/30/52 8:00 0.233 4 14.08 0.929 0.065 42 1/18/53 19:00 0.229 5 10.99 0.909 0.089 28 1/22/54 20:00 0.192 6 9.01 0.889 0.155 11 2/07/55 21:00 0.190 7 7.64 0.869 0.139 13 12/20/55 17:00 0.170 8 6.63 0.849 0.111 20 12/09/56 14:00 0.161 9 5.86 0.829 0.108 21 1/16/58 20:00 0.160 10 5.24 0.809 0.089 29 1/24/59 1:00 0.155 11 4.75 0.789 0.170 8 11/20/59 21:00 0.145 12 4.34 0.769 0.090 27 2/24/61 15:00 0.139 13 3.99 0.749 0.058 44 1/02/62 22:00 0.134 14 3.70 0.729 0.076 37 11/25/62 14:00 0.134 15 3.44 0.709 0.092 25 1/01/64 14:00 0.124 16 3.22 0.690 0.066 41 11/30/64 22:00 0.118 17 3.03 0.670 0.077 36 1/05/66 16:00 0.115 18 2.85 0.650 0.160 10 1/19/67 14:00 0.114 19 2.70 0.630 0.096 22 2/03/68 22:00 0.111 20 2.56 0.610 0.095 23 12/03/68 17:00 0.108 21 2.44 0.590 0.085 32 1/13/70 23:00 0.096 22 2.32 0.570 0.072 39 12/06/70 8:00 0.095 23 2.22 0.550 0.192 6 2/28/72 3:00 0.093 24 2.13 0.530 0.086 30 1/13/73 5:00 0.092 25 2.04 0.510 0.093 24 1/15/74 2:00 0.090 26 1.96 0.490 0.145 12 12/26/74 23:00 0.090 27 1.89 0.470 0.090 26 12/02/75 20:00 0.089 28 1.82 0.450 0.020 50 3/24/77 19:00 0.089 29 1.75 0.430 0.081 35 12/10/77 17:00 0.086 30 1.70 0.410 0.046 46 2/12/79 7:00 0.086 31 1.64 0.390 0.114 19 12/15/79 8:00 0.085 32 1.59 0.370 0.072 40 12/26/80 0:00 0.083 33 1.54 0.350 0.134 14 10/06/81 15:00 0.082 34 1.49 0.330 0.115 18 1/05/83 8:00 0.081 35 1.45 0.310 0.076 38 1/24/84 11:00 0.077 36 1.41 0.291 0.040 47 2/11/85 4:00 0.076 37 1.37 0.271 0.190 7 1/18/86 20:00 0.076 38 1.33 0.251 0.161 9 11/24/86 4:00 0.072 39 1.30 0.231 0.065 43 1/14/88 12:00 0.072 40 1.27 0.211 0.039 48 4/05/89 15:00 0.066 41 1.24 0.191 0.269 1 1/09/90 9:00 0.065 42 1.21 0.171 0.229 5 4/05/91 2:00 0.065 43 1.18 0.151 0.086 31 1/27/92 17:00 0.058 44 1.15 0.131 0.082 34 3/22/93 23:00 0.052 45 1.12 0.111 0.026 49 2/17/94 18:00 0.046 46 1.10 0.091 0.118 17 2/19/95 18:00 0.040 47 1.08 0.071 0.233 4 2/09/96 1:00 0.039 48 1.05 0.051 0.134 15 1/02/97 9:00 0.026 49 1.03 0.031 0.052 45 10/30/97 7:00 0.020 50 1.01 0.011 Computed Peaks 0.311 100.00 0.990 Computed Peaks 0.274 50.00 0.980 Computed Peaks 0.238 25.00 0.960 Computed Peaks 0.190 10.00 0.900 Computed Peaks 0.180 8.00 0.875 Computed Peaks 0.154 5.00 0.800 Computed Peaks 0.101 2.00 0.500 Computed Peaks 0.069 1.30 0.231 DevFT Peaks: Flow Frequency Analysis LogPearson III Coefficients Time Series File:devft.tsf Mean= -0.203 StdDev= 0.112 Project Location:Sea-Tac Skew= 0.418 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.644 21 2/16/49 21:00 1.15 1 89.50 0.989 1.10 2 3/03/50 16:00 1.10 2 32.13 0.969 0.665 20 2/09/51 2:00 1.05 3 19.58 0.949 0.507 40 10/15/51 13:00 1.03 4 14.08 0.929 0.490 45 3/24/53 15:00 0.890 5 10.99 0.909 0.598 27 12/19/53 19:00 0.881 6 9.01 0.889 0.616 23 11/25/54 2:00 0.823 7 7.64 0.869 0.601 25 11/18/55 15:00 0.820 8 6.63 0.849 0.719 15 12/09/56 14:00 0.778 9 5.86 0.829 0.628 22 12/25/57 16:00 0.771 10 5.24 0.809 0.467 47 11/18/58 13:00 0.744 11 4.75 0.789 0.607 24 11/20/59 5:00 0.739 12 4.34 0.769 0.538 35 2/14/61 21:00 0.735 13 3.99 0.749 0.527 38 11/22/61 2:00 0.722 14 3.70 0.729 0.538 36 12/15/62 2:00 0.719 15 3.44 0.709 0.599 26 12/31/63 23:00 0.705 16 3.22 0.690 0.536 37 12/21/64 4:00 0.703 17 3.03 0.670 0.541 34 1/05/66 16:00 0.685 18 2.85 0.650 0.823 7 11/13/66 19:00 0.680 19 2.70 0.630 0.890 5 8/24/68 16:00 0.665 20 2.56 0.610 0.494 42 12/03/68 16:00 0.644 21 2.44 0.590 0.547 33 1/13/70 22:00 0.628 22 2.32 0.570 0.522 39 12/06/70 8:00 0.616 23 2.22 0.550 0.820 8 2/27/72 7:00 0.607 24 2.13 0.530 0.480 46 1/13/73 2:00 0.601 25 2.04 0.510 0.584 28 11/28/73 9:00 0.599 26 1.96 0.490 0.771 10 12/26/74 23:00 0.598 27 1.89 0.470 0.494 43 12/02/75 20:00 0.584 28 1.82 0.450 0.568 30 8/26/77 2:00 0.580 29 1.75 0.430 0.778 9 9/17/78 2:00 0.568 30 1.70 0.410 0.680 19 9/08/79 15:00 0.564 31 1.64 0.390 0.705 16 12/14/79 21:00 0.559 32 1.59 0.370 0.735 13 11/21/80 11:00 0.547 33 1.54 0.350 1.03 4 10/06/81 0:00 0.541 34 1.49 0.330 0.722 14 10/28/82 16:00 0.538 35 1.45 0.310 0.580 29 1/03/84 1:00 0.538 36 1.41 0.291 0.492 44 6/06/85 22:00 0.536 37 1.37 0.271 0.703 17 1/18/86 16:00 0.527 38 1.33 0.251 0.881 6 10/26/86 0:00 0.522 39 1.30 0.231 0.386 49 11/11/87 0:00 0.507 40 1.27 0.211 0.500 41 8/21/89 17:00 0.500 41 1.24 0.191 1.15 1 1/09/90 6:00 0.494 42 1.21 0.171 1.05 3 11/24/90 8:00 0.494 43 1.18 0.151 0.564 31 1/27/92 15:00 0.492 44 1.15 0.131 0.361 50 11/01/92 16:00 0.490 45 1.12 0.111 0.422 48 11/30/93 22:00 0.480 46 1.10 0.091 0.559 32 11/30/94 4:00 0.467 47 1.08 0.071 0.744 11 2/08/96 10:00 0.422 48 1.05 0.051 0.685 18 1/02/97 6:00 0.386 49 1.03 0.031 0.739 12 10/04/97 15:00 0.361 50 1.01 0.011 Computed Peaks 1.23 100.00 0.990 Computed Peaks 1.12 50.00 0.980 Computed Peaks 1.02 25.00 0.960 Computed Peaks 0.879 10.00 0.900 Computed Peaks 0.851 8.00 0.875 Computed Peaks 0.772 5.00 0.800 Computed Peaks 0.615 2.00 0.500 Computed Peaks 0.513 1.30 0.231 Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 0.00 H:1V Pond Bottom Length: 100.00 ft Pond Bottom Width: 59.50 ft Pond Bottom Area: 5950. sq. ft Top Area at 1 ft. FB: 5950. sq. ft 0.137 acres Effective Storage Depth: 8.00 ft Stage 0 Elevation: 0.00 ft Storage Volume: 47600. cu. ft 1.093 ac-ft Riser Head: 8.00 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.88 0.059 2 5.30 1.63 0.118 4.0 3 6.60 1.50 0.072 4.0 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 5950. 0.01 0.01 60. 0.001 0.002 0.00 5950. 0.02 0.02 119. 0.003 0.003 0.00 5950. 0.03 0.03 179. 0.004 0.003 0.00 5950. 0.04 0.04 238. 0.005 0.004 0.00 5950. 0.05 0.05 298. 0.007 0.005 0.00 5950. 0.06 0.06 357. 0.008 0.005 0.00 5950. 0.07 0.07 417. 0.010 0.006 0.00 5950. 0.23 0.23 1369. 0.031 0.010 0.00 5950. 0.39 0.39 2321. 0.053 0.013 0.00 5950. 0.54 0.54 3213. 0.074 0.015 0.00 5950. 0.70 0.70 4165. 0.096 0.017 0.00 5950. 0.86 0.86 5117. 0.117 0.019 0.00 5950. 1.01 1.01 6010. 0.138 0.021 0.00 5950. 1.17 1.17 6962. 0.160 0.022 0.00 5950. 1.33 1.33 7914. 0.182 0.024 0.00 5950. 1.48 1.48 8806. 0.202 0.025 0.00 5950. 1.64 1.64 9758. 0.224 0.027 0.00 5950. 1.80 1.80 10710. 0.246 0.028 0.00 5950. 1.96 1.96 11662. 0.268 0.029 0.00 5950. 2.11 2.11 12554. 0.288 0.030 0.00 5950. 2.27 2.27 13506. 0.310 0.031 0.00 5950. 2.43 2.43 14459. 0.332 0.032 0.00 5950. 2.58 2.58 15351. 0.352 0.033 0.00 5950. 2.74 2.74 16303. 0.374 0.034 0.00 5950. 2.90 2.90 17255. 0.396 0.035 0.00 5950. 3.05 3.05 18147. 0.417 0.036 0.00 5950. 3.21 3.21 19100. 0.438 0.037 0.00 5950. 3.37 3.37 20051. 0.460 0.038 0.00 5950. 3.52 3.52 20944. 0.481 0.039 0.00 5950. 3.68 3.68 21896. 0.503 0.040 0.00 5950. 3.84 3.84 22848. 0.525 0.041 0.00 5950. 3.99 3.99 23740. 0.545 0.042 0.00 5950. 4.15 4.15 24693. 0.567 0.042 0.00 5950. 4.31 4.31 25644. 0.589 0.043 0.00 5950. 4.47 4.47 26596. 0.611 0.044 0.00 5950. 4.62 4.62 27489. 0.631 0.045 0.00 5950. 4.78 4.78 28441. 0.653 0.045 0.00 5950. 4.94 4.94 29393. 0.675 0.046 0.00 5950. 5.09 5.09 30286. 0.695 0.047 0.00 5950. 5.25 5.25 31237. 0.717 0.048 0.00 5950. 5.30 5.30 31535. 0.724 0.048 0.00 5950. 5.32 5.32 31654. 0.727 0.048 0.00 5950. 5.33 5.33 31713. 0.728 0.050 0.00 5950. 5.35 5.35 31832. 0.731 0.053 0.00 5950. 5.37 5.37 31951. 0.734 0.057 0.00 5950. 5.38 5.38 32011. 0.735 0.062 0.00 5950. 5.40 5.40 32130. 0.738 0.068 0.00 5950. 5.42 5.42 32249. 0.740 0.073 0.00 5950. 5.44 5.44 32368. 0.743 0.075 0.00 5950. 5.59 5.59 33261. 0.764 0.088 0.00 5950. 5.75 5.75 34213. 0.785 0.098 0.00 5950. 5.91 5.91 35164. 0.807 0.106 0.00 5950. 6.06 6.06 36057. 0.828 0.114 0.00 5950. 6.22 6.22 37009. 0.850 0.120 0.00 5950. 6.38 6.38 37961. 0.871 0.127 0.00 5950. 6.53 6.53 38854. 0.892 0.133 0.00 5950. 6.60 6.60 39270. 0.902 0.135 0.00 5950. 6.62 6.62 39389. 0.904 0.136 0.00 5950. 6.63 6.63 39449. 0.906 0.138 0.00 5950. 6.65 6.65 39568. 0.908 0.141 0.00 5950. 6.66 6.66 39627. 0.910 0.145 0.00 5950. 6.68 6.68 39746. 0.912 0.149 0.00 5950. 6.69 6.69 39806. 0.914 0.155 0.00 5950. 6.71 6.71 39925. 0.917 0.159 0.00 5950. 6.73 6.73 40043. 0.919 0.161 0.00 5950. 6.88 6.88 40936. 0.940 0.177 0.00 5950. 7.04 7.04 41888. 0.962 0.190 0.00 5950. 7.20 7.20 42840. 0.983 0.201 0.00 5950. 7.35 7.35 43732. 1.004 0.212 0.00 5950. 7.51 7.51 44685. 1.026 0.222 0.00 5950. 7.67 7.67 45637. 1.048 0.231 0.00 5950. 7.82 7.82 46529. 1.068 0.239 0.00 5950. 7.98 7.98 47481. 1.090 0.248 0.00 5950. 8.00 8.00 47600. 1.093 0.249 0.00 5950. 8.10 8.10 48195. 1.106 0.562 0.00 5950. 8.20 8.20 48790. 1.120 1.130 0.00 5950. 8.30 8.30 49385. 1.134 1.860 0.00 5950. 8.40 8.40 49980. 1.147 2.660 0.00 5950. 8.50 8.50 50575. 1.161 2.950 0.00 5950. 8.60 8.60 51170. 1.175 3.210 0.00 5950. 8.70 8.70 51765. 1.188 3.450 0.00 5950. 8.80 8.80 52360. 1.202 3.670 0.00 5950. 8.90 8.90 52955. 1.216 3.880 0.00 5950. 9.00 9.00 53550. 1.229 4.080 0.00 5950. 9.10 9.10 54145. 1.243 4.270 0.00 5950. 9.20 9.20 54740. 1.257 4.450 0.00 5950. 9.30 9.30 55335. 1.270 4.620 0.00 5950. 9.40 9.40 55930. 1.284 4.790 0.00 5950. 9.50 9.50 56525. 1.298 4.950 0.00 5950. 9.60 9.60 57120. 1.311 5.100 0.00 5950. 9.70 9.70 57715. 1.325 5.250 0.00 5950. 9.80 9.80 58310. 1.339 5.400 0.00 5950. 9.90 9.90 58905. 1.352 5.540 0.00 5950. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.66 0.22 7.41 7.41 44111. 1.013 2 0.74 0.21 7.28 7.28 43317. 0.994 3 1.15 0.18 6.98 6.98 41505. 0.953 4 0.70 0.17 6.82 6.82 40608. 0.932 5 0.61 0.16 6.76 6.76 40203. 0.923 6 1.03 0.10 5.83 5.83 34671. 0.796 7 0.62 0.04 3.78 3.78 22515. 0.517 8 0.56 0.04 4.25 4.25 25266. 0.580 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.22 0.03 ******** ******* 0.23 2 0.21 0.03 ******** ******* 0.22 3 0.18 0.05 ******** ******* 0.19 4 0.17 0.03 ******** ******* 0.18 5 0.16 0.03 ******** ******* 0.17 6 0.10 0.05 ******** ******* 0.11 7 0.04 0.03 ******** ******* 0.06 8 0.04 0.03 ******** ******* 0.06 ---------------------------------- Route Time Series through Facility Inflow Time Series File:devft.tsf Outflow Time Series File:RDout.tsf POC Time Series File:DSout Inflow/Outflow Analysis Peak Inflow Discharge: 1.15 CFS at 6:00 on Jan 9 in 1990 Peak Outflow Discharge: 0.229 CFS at 20:00 on Feb 9 in 1951 Peak Reservoir Stage: 7.64 Ft Peak Reservoir Elev: 7.64 Ft Peak Reservoir Storage: 45436. Cu-Ft : 1.043 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.240 CFS at 19:00 on Feb 9 in 1951 Point of Compliance File:DSout.tsf Flow Frequency Analysis LogPearson III Coefficients Time Series File:rdout.tsf Mean= -1.187 StdDev= 0.260 Project Location:Sea-Tac Skew= 0.716 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.042 38 2/22/49 22:00 0.229 7.64 1 89.50 0.989 0.092 16 1/22/50 6:00 0.214 7.38 2 32.13 0.969 0.229 1 2/09/51 20:00 0.185 6.98 3 19.58 0.949 0.037 43 2/04/52 8:00 0.181 6.93 4 14.08 0.929 0.063 22 1/31/53 15:00 0.175 6.86 5 10.99 0.909 0.044 33 1/07/54 21:00 0.172 6.83 6 9.01 0.889 0.042 37 2/08/55 21:00 0.167 6.78 7 7.64 0.869 0.127 10 1/06/56 11:00 0.164 6.76 8 6.63 0.849 0.043 35 2/26/57 12:00 0.129 6.43 9 5.86 0.829 0.047 24 1/17/58 11:00 0.127 6.37 10 5.24 0.809 0.042 36 1/27/59 1:00 0.118 6.18 11 4.75 0.789 0.164 8 11/21/59 3:00 0.107 5.93 12 4.34 0.769 0.097 14 11/24/60 11:00 0.103 5.84 13 3.99 0.749 0.036 46 12/24/61 6:00 0.097 5.73 14 3.70 0.729 0.047 25 11/30/62 20:00 0.095 5.70 15 3.44 0.709 0.089 17 11/19/63 17:00 0.092 5.65 16 3.22 0.690 0.103 13 12/01/64 8:00 0.089 5.60 17 3.03 0.670 0.045 30 1/07/66 4:00 0.080 5.50 18 2.85 0.650 0.080 18 12/15/66 8:00 0.074 5.43 19 2.70 0.630 0.045 32 1/20/68 22:00 0.068 5.40 20 2.56 0.610 0.045 31 12/11/68 10:00 0.067 5.40 21 2.44 0.590 0.048 23 1/27/70 5:00 0.063 5.38 22 2.32 0.570 0.045 28 12/07/70 13:00 0.048 5.25 23 2.22 0.550 0.181 4 3/06/72 22:00 0.047 5.11 24 2.13 0.530 0.107 12 12/26/72 6:00 0.047 5.04 25 2.04 0.510 0.046 26 1/18/74 20:00 0.046 4.94 26 1.96 0.490 0.041 39 1/14/75 1:00 0.046 4.88 27 1.89 0.470 0.044 34 12/04/75 6:00 0.045 4.79 28 1.82 0.450 0.033 49 8/26/77 8:00 0.045 4.78 29 1.75 0.430 0.068 20 12/15/77 19:00 0.045 4.71 30 1.70 0.410 0.033 48 2/13/79 0:00 0.045 4.56 31 1.64 0.390 0.172 6 12/17/79 20:00 0.045 4.56 32 1.59 0.370 0.045 29 12/30/80 23:00 0.044 4.49 33 1.54 0.350 0.118 11 10/06/81 19:00 0.044 4.49 34 1.49 0.330 0.046 27 1/08/83 5:00 0.043 4.28 35 1.45 0.310 0.036 45 12/10/83 20:00 0.042 4.01 36 1.41 0.291 0.038 42 11/04/84 8:00 0.042 4.01 37 1.37 0.271 0.067 21 1/19/86 7:00 0.042 3.92 38 1.33 0.251 0.129 9 11/24/86 9:00 0.041 3.90 39 1.30 0.231 0.040 40 12/10/87 8:00 0.040 3.76 40 1.27 0.211 0.037 44 11/05/88 23:00 0.038 3.38 41 1.24 0.191 0.185 3 1/09/90 14:00 0.038 3.35 42 1.21 0.171 0.175 5 11/24/90 16:00 0.037 3.20 43 1.18 0.151 0.074 19 1/31/92 23:00 0.037 3.20 44 1.15 0.131 0.035 47 1/26/93 5:00 0.036 3.13 45 1.12 0.111 0.032 50 2/17/94 23:00 0.036 3.12 46 1.10 0.091 0.095 15 12/27/94 7:00 0.035 2.93 47 1.08 0.071 0.214 2 2/09/96 3:00 0.033 2.58 48 1.05 0.051 0.167 7 1/02/97 12:00 0.033 2.51 49 1.03 0.031 0.038 41 1/25/98 0:00 0.032 2.38 50 1.01 0.011 Computed Peaks 0.355 8.03 100.00 0.990 Computed Peaks 0.276 8.01 50.00 0.980 Computed Peaks 0.212 7.35 25.00 0.960 Computed Peaks 0.145 6.66 10.00 0.900 Computed Peaks 0.133 6.54 8.00 0.875 Computed Peaks 0.104 5.88 5.00 0.800 Computed Peaks 0.061 5.38 2.00 0.500 Computed Peaks 0.041 3.80 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:dsout.tsf Mean= -1.096 StdDev= 0.207 Project Location:Sea-Tac Skew= 0.905 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.062 32 2/16/49 21:00 0.240 1 89.50 0.989 0.097 16 1/22/50 4:00 0.225 2 32.13 0.969 0.240 1 2/09/51 19:00 0.193 3 19.58 0.949 0.050 45 1/30/52 8:00 0.189 4 14.08 0.929 0.065 24 1/31/53 15:00 0.182 5 10.99 0.909 0.058 39 12/19/53 19:00 0.179 6 9.01 0.889 0.065 25 11/25/54 2:00 0.174 7 7.64 0.869 0.134 10 1/06/56 9:00 0.170 8 6.63 0.849 0.065 23 12/09/56 14:00 0.138 9 5.86 0.829 0.063 28 1/16/58 16:00 0.134 10 5.24 0.809 0.062 31 1/26/59 20:00 0.127 11 4.75 0.789 0.170 8 11/21/59 2:00 0.113 12 4.34 0.769 0.102 14 11/24/60 9:00 0.109 13 3.99 0.749 0.050 46 12/22/61 17:00 0.102 14 3.70 0.729 0.062 30 11/30/62 12:00 0.099 15 3.44 0.709 0.093 17 11/19/63 15:00 0.097 16 3.22 0.690 0.109 13 12/01/64 6:00 0.093 17 3.03 0.670 0.064 26 1/05/66 16:00 0.084 18 2.85 0.650 0.084 18 12/15/66 7:00 0.077 19 2.70 0.630 0.062 33 8/24/68 16:00 0.073 20 2.56 0.610 0.056 40 12/03/68 16:00 0.070 21 2.44 0.590 0.058 35 1/25/70 3:00 0.069 22 2.32 0.570 0.062 29 12/06/70 8:00 0.065 23 2.22 0.550 0.189 4 3/06/72 21:00 0.065 24 2.13 0.530 0.113 12 12/26/72 5:00 0.065 25 2.04 0.510 0.058 36 11/11/73 17:00 0.064 26 1.96 0.490 0.069 22 12/26/74 23:00 0.063 27 1.89 0.470 0.056 41 12/02/75 20:00 0.063 28 1.82 0.450 0.058 37 8/26/77 2:00 0.062 29 1.75 0.430 0.070 21 12/15/77 19:00 0.062 30 1.70 0.410 0.044 49 11/19/78 3:00 0.062 31 1.64 0.390 0.179 6 12/17/79 19:00 0.062 32 1.59 0.370 0.063 27 11/21/80 11:00 0.062 33 1.54 0.350 0.127 11 10/06/81 15:00 0.060 34 1.49 0.330 0.058 38 1/05/83 8:00 0.058 35 1.45 0.310 0.053 44 1/03/84 1:00 0.058 36 1.41 0.291 0.050 47 11/03/84 11:00 0.058 37 1.37 0.271 0.073 20 1/18/86 16:00 0.058 38 1.33 0.251 0.138 9 11/24/86 6:00 0.058 39 1.30 0.231 0.054 42 12/09/87 16:00 0.056 40 1.27 0.211 0.054 43 11/05/88 14:00 0.056 41 1.24 0.191 0.193 3 1/09/90 13:00 0.054 42 1.21 0.171 0.182 5 11/24/90 15:00 0.054 43 1.18 0.151 0.077 19 1/31/92 22:00 0.053 44 1.15 0.131 0.045 48 3/22/93 22:00 0.050 45 1.12 0.111 0.044 50 2/17/94 18:00 0.050 46 1.10 0.091 0.099 15 12/27/94 6:00 0.050 47 1.08 0.071 0.225 2 2/09/96 2:00 0.045 48 1.05 0.051 0.174 7 1/02/97 11:00 0.044 49 1.03 0.031 0.060 34 10/04/97 15:00 0.044 50 1.01 0.011 Computed Peaks 0.329 100.00 0.990 Computed Peaks 0.264 50.00 0.980 Computed Peaks 0.210 25.00 0.960 Computed Peaks 0.152 10.00 0.900 Computed Peaks 0.142 8.00 0.875 Computed Peaks 0.116 5.00 0.800 Computed Peaks 0.075 2.00 0.500 Computed Peaks 0.055 1.30 0.231 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 209884 47.919 47.919 52.081 0.521E+00 0.010 54132 12.359 60.278 39.722 0.397E+00 0.016 55070 12.573 72.851 27.149 0.271E+00 0.023 43287 9.883 82.734 17.266 0.173E+00 0.029 31743 7.247 89.981 10.019 0.100E+00 0.035 23586 5.385 95.366 4.634 0.463E-01 0.042 11497 2.625 97.991 2.009 0.201E-01 0.048 7317 1.671 99.661 0.339 0.339E-02 0.055 189 0.043 99.704 0.296 0.296E-02 0.061 82 0.019 99.723 0.277 0.277E-02 0.068 77 0.018 99.741 0.259 0.259E-02 0.074 74 0.017 99.758 0.242 0.242E-02 0.080 176 0.040 99.798 0.202 0.202E-02 0.087 122 0.028 99.826 0.174 0.174E-02 0.093 116 0.026 99.852 0.148 0.148E-02 0.100 122 0.028 99.880 0.120 0.120E-02 0.106 93 0.021 99.901 0.099 0.989E-03 0.112 74 0.017 99.918 0.082 0.820E-03 0.119 90 0.021 99.939 0.061 0.614E-03 0.125 63 0.014 99.953 0.047 0.470E-03 0.132 61 0.014 99.967 0.033 0.331E-03 0.138 31 0.007 99.974 0.026 0.260E-03 0.145 7 0.002 99.976 0.024 0.244E-03 0.151 7 0.002 99.977 0.023 0.228E-03 0.157 4 0.001 99.978 0.022 0.219E-03 0.164 20 0.005 99.983 0.017 0.174E-03 0.170 19 0.004 99.987 0.013 0.130E-03 0.177 13 0.003 99.990 0.010 0.100E-03 0.183 13 0.003 99.993 0.007 0.708E-04 0.190 7 0.002 99.995 0.005 0.548E-04 0.196 3 0.001 99.995 0.005 0.479E-04 0.202 3 0.001 99.996 0.004 0.411E-04 0.209 5 0.001 99.997 0.003 0.297E-04 0.215 6 0.001 99.998 0.002 0.160E-04 0.222 3 0.001 99.999 0.001 0.913E-05 0.228 3 0.001 100.000 0.000 0.228E-05 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 210224 47.996 47.996 52.004 0.520E+00 0.010 54245 12.385 60.381 39.619 0.396E+00 0.017 55637 12.703 73.084 26.916 0.269E+00 0.024 42396 9.679 82.763 17.237 0.172E+00 0.030 32186 7.348 90.111 9.889 0.989E-01 0.037 22979 5.246 95.358 4.642 0.464E-01 0.044 12108 2.764 98.122 1.878 0.188E-01 0.051 5797 1.324 99.446 0.554 0.554E-02 0.057 908 0.207 99.653 0.347 0.347E-02 0.064 242 0.055 99.708 0.292 0.292E-02 0.071 129 0.029 99.738 0.262 0.262E-02 0.078 100 0.023 99.761 0.239 0.239E-02 0.084 181 0.041 99.802 0.198 0.198E-02 0.091 122 0.028 99.830 0.170 0.170E-02 0.098 123 0.028 99.858 0.142 0.142E-02 0.105 121 0.028 99.885 0.115 0.115E-02 0.111 83 0.019 99.904 0.096 0.957E-03 0.118 81 0.018 99.923 0.077 0.772E-03 0.125 74 0.017 99.940 0.060 0.603E-03 0.132 69 0.016 99.955 0.045 0.445E-03 0.138 58 0.013 99.969 0.031 0.313E-03 0.145 16 0.004 99.972 0.028 0.276E-03 0.152 11 0.003 99.975 0.025 0.251E-03 0.158 8 0.002 99.977 0.023 0.233E-03 0.165 12 0.003 99.979 0.021 0.205E-03 0.172 19 0.004 99.984 0.016 0.162E-03 0.179 17 0.004 99.988 0.012 0.123E-03 0.185 14 0.003 99.991 0.009 0.913E-04 0.192 13 0.003 99.994 0.006 0.616E-04 0.199 3 0.001 99.995 0.005 0.548E-04 0.206 6 0.001 99.996 0.004 0.411E-04 0.212 2 0.000 99.996 0.004 0.365E-04 0.219 3 0.001 99.997 0.003 0.297E-04 0.226 7 0.002 99.999 0.001 0.137E-04 0.233 2 0.000 99.999 0.001 0.913E-05 0.239 2 0.000 100.000 0.000 0.457E-05 Duration Comparison Anaylsis Base File: predevft.tsf New File: dsout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New %Change Probability Base New %Change 0.050 | 0.84E-02 0.60E-02 -29.2 | 0.84E-02 0.050 0.048 -4.0 0.067 | 0.44E-02 0.28E-02 -36.1 | 0.44E-02 0.067 0.053 -20.0 0.084 | 0.25E-02 0.20E-02 -18.7 | 0.25E-02 0.084 0.076 -9.4 0.101 | 0.14E-02 0.13E-02 -7.9 | 0.14E-02 0.101 0.098 -2.6 0.117 | 0.86E-03 0.80E-03 -7.2 | 0.86E-03 0.117 0.115 -1.9 0.134 | 0.54E-03 0.39E-03 -27.5 | 0.54E-03 0.134 0.128 -4.9 0.151 | 0.36E-03 0.25E-03 -29.5 | 0.36E-03 0.151 0.136 -10.1 0.168 | 0.25E-03 0.18E-03 -25.0 | 0.25E-03 0.168 0.154 -8.5 0.185 | 0.15E-03 0.94E-04 -36.9 | 0.15E-03 0.185 0.173 -6.3 0.202 | 0.75E-04 0.50E-04 -33.3 | 0.75E-04 0.202 0.190 -5.7 0.218 | 0.43E-04 0.30E-04 -31.6 | 0.43E-04 0.218 0.206 -5.9 0.235 | 0.18E-04 0.68E-05 -62.5 | 0.18E-04 0.235 0.224 -4.7 0.252 | 0.46E-05 0.00E+00 -100.0 | 0.46E-05 0.252 0.239 -5.0 0.269 | 0.23E-05 0.00E+00 -100.0 | 0.23E-05 0.269 0.240 -10.8 There is no positive excursion Maximum negative excursion = 0.016 cfs (-22.2%) occurring at 0.074 cfs on the Base Data:predevft.tsf and at 0.058 cfs on the New Data:dsout.tsf 31 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The stormwater drainage conveyance system has been sized to convey the KCRTS 15 minute time series 25 year design storm event and to contain the 100 year design storm event. The calculations are included following this page. CONVEYANCE CALCULATION Pipe Pervious Area (acres) Impervious Area (acres) Total Area (acres) 25-year Total Flow (cfs) 100-year Total Flow (cfs) Pipe Diameter (in) Pipe Diameter (ft) Area (ft2) Wet Perimeter (ft) Hydraulic Radius (ft) Slope (ft/ft)Pipe n Capacity (cfs) Velocity @25- year Capacity (ft/sec) 25 year % Capacity (cfs) 100 year % Capacity (cfs) CB #16 to CB #15 0.01 0.11 0.13 0.31 0.36 12 1 0.785 3.142 0.250 0.010 0.013 3.50 4.46 9%10% CB #15 to CB #14 0.02 0.08 0.10 0.52 0.61 12 1 0.785 3.142 0.250 0.006 0.013 2.78 3.54 19%22% CB #14 to CB #13 0.10 0.18 0.28 1.02 1.19 12 1 0.785 3.142 0.250 0.022 0.013 5.31 6.75 19%22% CB #13 to CB #12 0.00 0.00 0.00 1.02 1.19 12 1 0.785 3.142 0.250 0.113 0.013 12.02 15.31 8%10% CB #12 to Pond 0.00 0.00 0.00 1.02 1.19 12 1 0.785 3.142 0.250 0.110 0.013 11.87 15.11 9%10% CB #9 to CB #8 0.25 0.37 0.61 1.00 1.17 12 1 0.785 3.142 0.250 0.010 0.013 3.64 4.63 27%32% CB #8 to CB #7 0.09 0.04 0.12 1.09 1.28 12 1 0.785 3.142 0.250 0.030 0.013 6.20 7.90 18%21% CB #7 to CB #6 0.01 0.02 0.02 1.15 1.34 12 1 0.785 3.142 0.250 0.026 0.013 5.76 7.33 20%23% CB #11 to CB #10 0.13 0.29 0.41 0.78 0.91 12 1 0.785 3.142 0.250 0.005 0.013 2.53 3.22 31%36% CB #10 to CB #6 0.02 0.05 0.07 0.92 1.08 12 1 0.785 3.142 0.250 0.008 0.013 3.21 4.08 29%34% CB #6 to CB #1 0.06 0.12 0.18 2.40 2.80 12 1 0.785 3.142 0.250 0.144 0.013 13.57 17.28 18%21% CB #5 to CB #4 0.18 0.40 0.58 1.08 1.27 12 1 0.785 3.142 0.250 0.005 0.013 2.57 3.27 42%49% CB #4 to CB #2 0.00 0.00 0.00 1.08 1.27 12 1 0.785 3.142 0.250 0.005 0.013 2.48 3.16 44%51% CB #3 to CB #2 0.15 0.31 0.46 0.85 0.99 12 1 0.785 3.142 0.250 0.079 0.013 10.03 12.77 8%10% CB #2 to CB #1 0.06 0.11 0.17 2.24 2.61 12 1 0.785 3.142 0.250 0.006 0.013 2.77 3.52 81%94% CB #1 to Pond 0.01 0.03 0.04 2.31 2.70 12 1 0.785 3.142 0.250 0.095 0.013 10.99 14.00 21%25% BACKWATER CALCULATION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Pipe 100-year Flow (cfs) Pipe Length (ft) Pipe Diameter (in) Pipe n** I.E. Out (ft) I.E. In (ft) Pipe Area (ft) Velocity (ft/s) Velocity Head (ft/s) Tailwater Elevation (ft) Friction Loss Entrance HGL Elevation (ft) Entrance Head Loss (ft) Exit Head Loss (ft) Outlet Control Elevation (ft) Inlet Control Elevation (ft) Appr Vel Head (ft) Bend Head Loss (ft) Junction Head Loss (ft) HW Elevation (ft) Upstream CB Grate Elevation (ft) CB Grate Elev. - HW Elev. (ft) CB #1 to Pond 2.7 94 12 0.011 447.0 455.9 0.79 3.44 0.18 458.8 0.38 459.1 0.09 0.18 459.4 457.0 0.17 0.22 0.00 459.4 466.8 7.4 CB #2 to CB #1 2.6 70 12 0.011 455.9 456.3 0.79 3.33 0.17 459.4 0.27 459.7 0.09 0.17 460.0 457.4 0.04 0.05 0.07 459.9 462.7 2.7 CB #3 to CB #2 1.0 17 12 0.011 456.3 457.7 0.79 1.26 0.02 459.9 0.01 459.9 0.01 0.02 460.0 458.4 0.00 0.00 0.00 459.9 462.7 2.7 CB #4 to CB #2 1.3 31 12 0.011 456.3 456.5 0.79 1.61 0.04 459.9 0.03 460.0 0.02 0.04 460.0 457.2 0.04 0.05 0.00 460.0 461.7 1.6 CB #5 to CB #4 1.3 31 12 0.011 456.5 456.6 0.79 1.61 0.04 460.0 0.03 460.1 0.02 0.04 460.1 457.4 0.00 0.00 0.00 460.1 461.1 1.0 CB #6 to CB #1 2.8 70 12 0.011 455.9 466.0 0.79 3.57 0.20 459.9 0.31 460.2 0.10 0.20 460.5 467.1 0.05 0.06 0.08 467.0 471.0 4.0 CB #10 to CB #6 1.1 31 12 0.011 466.0 466.3 0.79 1.37 0.03 467.0 0.02 467.1 0.01 0.03 467.1 467.0 0.02 0.03 0.00 467.1 471.3 4.1 CB #11 to CB #10 0.9 32 12 0.011 466.3 466.4 0.79 1.16 0.02 467.1 0.01 467.1 0.01 0.02 467.2 467.1 0.00 0.00 0.00 467.1 471.3 4.1 CB #7 to CB #6 1.3 100 12 0.011 466.0 468.6 0.79 1.70 0.05 467.0 0.10 467.1 0.02 0.05 467.2 469.4 0.04 0.05 0.00 469.4 473.6 4.2 CB #8 to CB #7 1.3 77 12 0.011 468.6 470.9 0.79 1.63 0.04 469.4 0.07 469.5 0.02 0.04 469.5 471.7 0.03 0.04 0.00 471.7 475.9 4.2 CB #9 to CB #8 1.2 27 12 0.011 470.9 471.2 0.79 1.48 0.03 471.7 0.02 471.7 0.02 0.03 471.8 472.0 0.00 0.00 0.00 471.9 476.2 4.3 CB #12 to Pond 1.2 29 12 0.011 446.0 449.2 0.79 1.52 0.04 458.8 0.02 458.8 0.02 0.04 458.8 449.9 0.04 0.05 0.00 458.8 454.2 -4.6* CB #13 to CB #12 1.2 67 12 0.011 449.2 456.8 0.79 1.52 0.04 458.8 0.05 458.9 0.02 0.04 458.9 457.5 0.04 0.05 0.00 459.0 461.9 2.9 CB #14 to CB #13 1.2 73 12 0.011 456.8 458.4 0.79 1.52 0.04 459.0 0.06 459.0 0.02 0.04 459.1 459.2 0.01 0.01 0.00 459.1 465.8 6.7 CB #15 to CB #14 0.6 28 12 0.011 458.4 458.6 0.79 0.78 0.01 459.1 0.01 459.1 0.00 0.01 459.1 459.3 0.00 0.00 0.00 459.3 463.6 4.3 CB #16 to CB #15 0.4 25 12 0.011 458.6 458.8 0.79 0.46 0.00 459.3 0.00 459.3 0.00 0.00 459.3 459.5 0.00 0.00 0.00 459.5 463.8 4.3 * The rim elevation of this CB will be located in the detention pond and will be below the top of live storage. ** The Manning's n used in Backwater analysis differs from the Conveyance analysis per 2009 KCSWDM, Section 4.2, Table 4.2.1.D. 32 6. SPECIAL REPORTS AND STUDIES Following are the reports and studies referenced for the proposed development: • Geotechnical Engineering Report, by The Riley Group, Inc., dated July 08, 2015 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone 425.415.0551 ♦ Fax 425.415.0311 www.riley-group.com GEOTECHNICAL ENGINEERING REPORT PREPARED BY: THE RILEY GROUP, INC. 17522 BOTHELL WAY NORTHEAST BOTHELL, WASHINGTON 98011 PREPARED FOR: NORDIC RIDGE, LLC 15 LAKE BELLEVUE DRIVE, SUITE 102 BELLEVUE, WASHINGTON 98005 RGI PROJECT NO. 2015-097 NORDIC RIDGE PLAT 17709 116TH AVENUE SOUTHEAST RENTON, WASHINGTON JULY 8, 2015 Geotechnical Engineering Report i July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 TABLE OF CONTENTS 1.0 INTRODUCTION ............................................................................................................................... 1 2.0 PROJECT DESCRIPTION ............................................................................................................... 1 3.0 FIELD EXPLORATION AND LABORATORY TESTING .......................................................... 1 3.1 FIELD EXPLORATION ................................................................................................................................... 1 3.2 LABORATORY TESTING ................................................................................................................................ 2 4.0 SITE CONDITIONS ........................................................................................................................... 2 4.1 SURFACE .................................................................................................................................................. 2 4.2 GEOLOGY ................................................................................................................................................. 2 4.3 SOILS ....................................................................................................................................................... 2 4.4 GROUNDWATER ........................................................................................................................................ 3 4.5 SEISMIC CONSIDERATIONS ........................................................................................................................... 3 4.6 GEOLOGIC HAZARD AREAS .......................................................................................................................... 4 5.0 DISCUSSION AND RECOMMENDATIONS ................................................................................. 4 5.1 GEOTECHNICAL CONSIDERATIONS ................................................................................................................. 4 5.2 EARTHWORK ............................................................................................................................................. 4 5.2.1 Erosion and Sediment Control ..................................................................................................... 4 5.2.2 Stripping ....................................................................................................................................... 5 5.2.3 Excavations................................................................................................................................... 6 5.2.4 Site Preparation ........................................................................................................................... 6 5.2.5 Structural Fill ................................................................................................................................ 7 5.2.6 Cut and Fill Slopes ........................................................................................................................ 9 5.2.7 Wet Weather Construction Considerations ................................................................................. 9 5.3 FOUNDATIONS .......................................................................................................................................... 9 5.4 RETAINING WALLS ................................................................................................................................... 10 5.4.1 Cast-In-Place Walls ..................................................................................................................... 10 5.5 SLAB-ON-GRADE CONSTRUCTION ............................................................................................................... 11 5.6 DRAINAGE .............................................................................................................................................. 11 5.6.1 Surface ....................................................................................................................................... 11 5.6.2 Subsurface .................................................................................................................................. 12 5.6.3 Infiltration .................................................................................................................................. 12 5.7 UTILITIES ................................................................................................................................................ 12 5.8 PAVEMENTS ............................................................................................................................................ 12 6.0 ADDITIONAL SERVICES .............................................................................................................. 13 7.0 LIMITATIONS ................................................................................................................................. 13 LIST OF FIGURES AND APPENDICES Figure 1 ..................................................................................................................... Site Vicinity Map Figure 2 ................................................................................................ Geotechnical Exploration Plan Figure 3 .................................................................................. Typical Retaining Wall Drainage Detail Figure 4 ................................................................................................... Typical Footing Drain Detail Appendix A .......................................................................... Field Exploration and Laboratory Testing Geotechnical Engineering Report ii July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 Executive Summary This Executive Summary should be used in conjunction with the entire Geotechnical Engineering Report (GER) for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the GER must be read in its entirety for a comprehensive understanding of the items contained herein. Section 7.0 should be read for an understanding of limitations. RGI’s geotechnical scope of work included the advancement of eight test pits to approximate depths of six to eight feet below existing site grades. Based on the information obtained from our subsurface exploration, the site is suitable for development of the proposed project. The following geotechnical considerations were identified: Soil Conditions: The soils encountered during field exploration include loose to very dense silty sand with gravel. Groundwater: No groundwater seepage was encountered during our subsurface exploration. However, iron oxide staining was observed at 3 to 4 feet indicating a perched seasonal groundwater table over the top of dense glacial till layer. Foundations: Foundations for the proposed building may be supported on conventional spread footings bearing on medium dense to dense native soil or structural fill Slab-on-grade: Slab-on-grade floors and slabs for the proposed building can be supported on medium dense to dense native soil or structural fill. Pavements: The following pavement sections are recommended in accordance with the preferred section in the King County Road Design and Construction Standards - 2007: ¾ For Residential Streets: 2 inches of Class ½ inch Hot Mix Asphalt (HMA) over 4 inches of Class ¾ or 1 inch HMA Geotechnical Engineering Report 1 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 1.0 Introduction This Geotechnical Engineering Report (GER) presents the results of the geotechnical engineering services provided for the Nordic Ridge Plat in Renton, King County, Washington. The purpose of this evaluation is to assess subsurface conditions and provide geotechnical recommendations for the construction of a residential plat. Our scope of services included field explorations, laboratory testing, engineering analyses, and preparation of this GER. The recommendations in the following sections of this GER are based upon our current understanding of the proposed site development as outlined below. If actual features vary or changes are made, RGI should review them in order to modify our recommendations as required. In addition, RGI requests to review the site grading plan, final design drawings and specifications when available to verify that our project understanding is correct and that our recommendations have been properly interpreted and incorporated into the project design and construction. 2.0 Project description The project site is located at 17709 116th Avenue Southeast in Renton, Washington. The approximate location of the site is shown on Figure 1. The site is currently occupied by a single family residence with outbuildings and pasture areas. We understand it is proposed to construct a residential development on the site with access roadways, underground utilities and storm water facilities. At the time of preparing this GER, building plans were not available for our review. Based on our experience with similar construction, RGI anticipates that the proposed residences will be supported on perimeter walls with bearing loads of two to four kips per linear foot, and a series of columns with a maximum load up to 70 kips. Slab-on-grade floor loading of 250 pounds per square foot (psf) are expected. 3.0 Field Exploration and Laboratory Testing 3.1 FIELD EXPLORATION On July 1, 2015, RGI observed the excavation of eight test pits. The approximate exploration locations are shown on Figure 2. Field logs of each exploration were prepared by the geologist that continuously observed the excavation. These logs included visual classifications of the materials encountered during drilling as well as our interpretation of the subsurface conditions between samples. The test pits logs included in Appendix A represent an interpretation of the field Geotechnical Engineering Report 2 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 logs and include modifications based on laboratory observation and analysis of the samples. 3.2 LABORATORY TESTING During the field exploration, a representative portion of each recovered sample was sealed in containers and transported to our laboratory for further visual and laboratory examination. Selected samples retrieved from the test pits were tested for moisture content and grain size analysis to aid in soil classification and provide input for the recommendations provided in this GER. The results and descriptions of the laboratory tests are enclosed in Appendix A. 4.0 Site Conditions 4.1 SURFACE The subject site is an irregular-shaped parcel of land approximately 3.63 acres in size. The site is bound to the north by Southeast Petrovitsky Road and residential property, to the east by 116th Avenue Southeast and residential property, to the south by residential property, and to the west by Southeast 177th Place and residential property. The site contains a single-family residence and several out-buildings in the central portion of the property, with the remainder of the site vegetated by grass. Several medium- diameter trees are located around the residence and in the southern portion of the property. Small-diameter trees ring a fenced off pasture in the northern portion of the site. The site slopes generally northeast at gradients of about 10 percent with an elevation change across the site of approximately 30 feet. 4.2 GEOLOGY Review of the Geologic Map of the Renton Quadrangle, King County, Washington, by D. R. Mullineaux (1965) indicates that the soil in the project vicinity is mapped as Ground moraine deposits (Qgt), which is light to dark gray, nonsorted, nonstratified mixture of clay, silt, sand, and gravel deposited by glacial ice. The deposit is generally very stiff and impermeable, often resulting in poorly drained bogs developing in relatively flat area. The deposit is usually 1 to 2 meters thick, but locally can be as much as 25 meters. These descriptions are generally similar to the findings in our field explorations. 4.3 SOILS The soils encountered during field exploration include loose to very dense silty sand with gravel. The soil generally becomes denser with depth. Geotechnical Engineering Report 3 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 More detailed descriptions of the subsurface conditions encountered are presented in the test pits included in Appendix A. Sieve analysis was performed on three selected soil samples. Grain size distribution curves are included in Appendix A. 4.4 GROUNDWATER No groundwater seepage was encountered during our subsurface exploration. However, iron oxide staining was observed at 3 to 4 feet indicating a perched seasonal groundwater table over the top of dense glacial till layer. It should be recognized that fluctuations of the groundwater table will occur due to seasonal variations in the amount of rainfall, runoff, and other factors not evident at the time the explorations were performed. In addition, perched water can develop within seams and layers contained in fill soils or higher permeability soils overlying less permeable soils following periods of heavy or prolonged precipitation. Therefore, groundwater levels during construction or at other times in the future may be higher or lower than the levels indicated on the logs. Groundwater level fluctuations should be considered when developing the design and construction plans for the project. 4.5 SEISMIC CONSIDERATIONS Based on the 2012 International Building Code (IBC), RGI recommends the follow seismic parameters for design. Table 1 2012 IBC Parameter Value Site Soil Class1 C2 Site Latitude 47.44399o N Site Longitude 122.18701o W Short Period Spectral Response Acceleration, SS (g) 1.386 1-Second Period Spectral Response Acceleration, S1 (g) 0.517 Adjusted Short Period Spectral Response Acceleration, SMS (g) 1.386 Adjusted 1-Second Period Spectral Response Acceleration, SM1 (g) 0.672 1. Note: In general accordance with Chapter 20 of ASCE 7. The Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. 2. Note: The 2012 IBC and ASCE 7 require a site soil profile determination extending to a depth of 100 feet for seismic site classification. The current scope of our services does not include the required 100 foot soil profile determination. Test pits extended to a maximum depth of 8 feet, and this seismic site class definition considers that very dense soil continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration. Geotechnical Engineering Report 4 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in water pressure induced by vibrations from a seismic event. Liquefaction mainly affects geologically recent deposits of fine-grained sands that are below the groundwater table. Soils of this nature derive their strength from intergranular friction. The generated water pressure or pore pressure essentially separates the soil grains and eliminates this intergranular friction, thus reducing or eliminating the soil’s strength. RGI reviewed the results of the field and laboratory testing and assessed the potential for liquefaction of the site’s soil during an earthquake. Since the site is underlain by glacial till, RGI considers that the possibility of liquefaction during an earthquake is minimal. 4.6 GEOLOGIC HAZARD AREAS Regulated geologically hazardous areas include erosion, landslide, earthquake, or other geological hazards. Based on the definition in the King County Code, the site does not contain geologically hazardous areas. 5.0 Discussion and Recommendations 5.1 GEOTECHNICAL CONSIDERATIONS Based on our study, the site is suitable for the proposed construction from a geotechnical standpoint. Foundations for the proposed building can be supported on conventional spread footings bearing on medium dense to dense native soil or structural fill. Slab-on- grade and pavements can be similarly supported. Detailed recommendations regarding the above issues and other geotechnical design considerations are provided in the following sections. These recommendations should be incorporated into the final design drawings and construction specifications. 5.2 EARTHWORK The earthwork for the project is expected to include mass grading to achieve lot and roadway grades, excavating the detention pond, installing underground utilities and preparing roadway subgrades. 5.2.1 EROSION AND SEDIMENT CONTROL Potential sources or causes of erosion and sedimentation depend on construction methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction sequencing and weather. The impacts on erosion-prone areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable city and/or county standards. Geotechnical Engineering Report 5 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 RGI recommends the following erosion control Best Management Practices (BMPs): ¾ Scheduling site preparation and grading for the drier summer and early fall months and undertaking activities that expose soil during periods of little or no rainfall ¾ Retaining existing vegetation whenever feasible ¾ Establishing a quarry spall construction entrance ¾ Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas ¾ Covering soil stockpiles with anchored plastic sheeting ¾ Revegetating or mulching exposed soils with a minimum 3-inch thickness of straw if surfaces will be left undisturbed for more than one day during wet weather or one week in dry weather ¾ Directing runoff away from exposed soils and slopes ¾ Minimizing the length and steepness of slopes with exposed soils and cover excavation surfaces with anchored plastic sheeting (Graded and disturbed slopes should be tracked in place with the equipment running perpendicular to the slope contours so that the track marks provide a texture to help resist erosion and channeling. Some sloughing and raveling of slopes with exposed or disturbed soil should be expected.) ¾ Decreasing runoff velocities with check dams, straw bales or coir wattles ¾ Confining sediment to the project site ¾ Inspecting and maintaining erosion and sediment control measures frequently (The contractor should be aware that inspection and maintenance of erosion control BMPs is critical toward their satisfactory performance. Repair and/or replacement of dysfunctional erosion control elements should be anticipated.) Permanent erosion protection should be provided by reestablishing vegetation using hydroseeding and/or landscape planting. Until the permanent erosion protection is established, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. 5.2.2 STRIPPING Stripping efforts should include removal of pavements, vegetation, organic materials, and deleterious debris from areas slated for building, pavement, and utility construction. The test pits encountered six to eight inches of topsoil and rootmass. Deeper areas of stripping may be required in forested or heavily vegetated areas of the site. Geotechnical Engineering Report 6 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 5.2.3 EXCAVATIONS All temporary cut slopes associated with the site and utility excavations should be adequately inclined to prevent sloughing and collapse. The site soils consist of medium dense to very dense silty sand with gravel. Accordingly, for excavations more than 4 feet but less than 20 feet in depth, the temporary side slopes should be laid back with a minimum slope inclination of 1H:1V (Horizontal:Vertical). The slope inclination may be increased to 3/4H:1V in the very dense till. If there is insufficient room to complete the excavations in this manner, or excavations greater than 20 feet in depth are planned, using temporary shoring to support the excavations should be considered. For open cuts at the site, RGI recommends: ¾ No traffic, construction equipment, stockpiles or building supplies are allowed at the top of cut slopes within a distance of at least five feet from the top of the cut ¾ Exposed soil along the slope is protected from surface erosion using waterproof tarps and/or plastic sheeting ¾ Construction activities are scheduled so that the length of time the temporary cut is left open is minimized ¾ Surface water is diverted away from the excavation ¾ The general condition of slopes should be observed periodically by a geotechnical engineer to confirm adequate stability and erosion control measures In all cases, however, appropriate inclinations will depend on the actual soil and groundwater conditions encountered during earthwork. Ultimately, the site contractor must be responsible for maintaining safe excavation slopes that comply with applicable OSHA or WISHA guidelines. 5.2.4 SITE PREPARATION RGI anticipates that some areas of loose or soft soil will be exposed upon completion of stripping and grubbing. Proofrolling and subgrade verification should be considered an essential step in site preparation. After stripping, grubbing, and prior to placement of structural fill, RGI recommends proofrolling building and pavement subgrades and areas to receive structural fill. These areas should moisture condition and compacted to a firm and unyielding condition in order to achieve a minimum compaction level of 95 percent of the modified proctor maximum dry density as determined by the American Society of Testing and Materials D1557-09 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (ASTM D1557). Proofrolling and adequate subgrade compaction can only be achieved when the soils are within approximately ± 2 percent moisture content of the optimum moisture content. Soils which appear firm after stripping and grubbing may be proofrolled with a heavy Geotechnical Engineering Report 7 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 compactor, loaded double-axle dump truck, or other heavy equipment under the observation of an RGI representative. This observer will assess the subgrade conditions prior to filling. The need for or advisability of proofrolling due to soil moisture conditions should be determined at the time of construction. In wet areas it may be necessary to hand probe the exposed subgrades in lieu of proofrolling with mechanical equipment. Subgrade soils that become disturbed due to elevated moisture conditions should be overexcavated to reveal firm, non-yielding, non-organic soils and backfilled with compacted structural fill. In order to maximize utilization of site soils as structural fill, RGI recommends that the earthwork portion of this project be completed during extended periods of warm and dry weather if possible. If earthwork is completed during the wet season (typically November through May) it will be necessary to take extra precautionary measures to protect subgrade soils. Wet season earthwork will require additional mitigative measures beyond that which would be expected during the drier summer and fall months. 5.2.5 STRUCTURAL FILL Once stripping, clearing and other preparing operations are complete, cuts and fills can be made to establish desired lot and roadway grades. Prior to placing fill, RGI recommends proof-rolling as described above. RGI recommends fill below the foundation and floor slab, behind retaining walls, and below pavement and hardscape surfaces be placed in accordance with the following recommendations for structural fill. The suitability of excavated site soils and import soils for compacted structural fill use will depend on the gradation and moisture content of the soil when it is placed. As the amount of fines (that portion passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve. Soils containing more than about 5 percent fines cannot be consistently compacted to a dense, non-yielding condition when the moisture content is more than 2 percent above or below optimum. Optimum moisture content is that moisture that results in the greatest compacted dry density with a specified compactive effort. Non-organic site soils are only considered suitable for structural fill provided that their moisture content is within about two percent of the optimum moisture level as determined by ASTM D1557. Excavated site soils may not be suitable for re-use as structural fill depending on the moisture content and weather conditions at the time of construction. If soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should be protected with plastic sheeting that is securely anchored. Even during dry weather, moisture conditioning (such as, windrowing and drying) of site soils to be reused as structural fill may be required. Even during the summer, delays in grading can occur due to excessively high moisture conditions of the soils or due to precipitation. If Geotechnical Engineering Report 8 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 wet weather occurs, the upper wetted portion of the site soils may need to be scarified and allowed to dry prior to further earthwork, or may need to be wasted from the site. The site soils are moisture sensitive and will not be useable for will in wet weather. If grading operations take place in the summer and fall months, it should be feasible to moisture condition and compact the native soil. If on-site soils are or become unusable, it may become necessary to import clean, granular soils to complete site work that meet the grading requirements listed in Table 2 to be used as structural fill. Table 2 Structural Fill Gradation U.S. Sieve Size Percent Passing 4 inches 100 No. 4 sieve 75 percent No. 200 sieve 5 percent * *Based on minus 3/4 inch fraction. Prior to use, an RGI representative should observe and test all materials imported to the site for use as structural fill. Structural fill materials should be placed in uniform loose layers not exceeding 12 inches and compacted as specified in Table 2. The soil’s maximum density and optimum moisture should be determined by ASTM D1557. Table 3 Structural Fill Compaction ASTM D1557 Location Material Type Minimum Compaction Percentage Moisture Content Range Foundations On-site granular or approved imported fill soils: 95 +2 -2 Retaining Wall Backfill On-site granular or approved imported fill soils: 92 +2 -2 Slab-on-grade On-site granular or approved imported fill soils: 95 +2 -2 General Fill (non- structural areas) On-site soils or approved imported fill soils: 90 +3 -2 Pavement – Subgrade and Base Course On-site granular or approved imported fill soils: 95 +2 -2 Placement and compaction of structural fill should be observed by RGI. A representative number of in-place density tests should be performed as the fill is being placed to confirm that the recommended level of compaction is achieved. Geotechnical Engineering Report 9 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 5.2.6 CUT AND FILL SLOPES All permanent cut and fill slopes (except interior slopes of detention pond) should be graded with a finished inclination no greater than 2H:1V. The interior slopes of the detention pond must be graded with a slope gradient no steeper than 3H:1V. Upon completion of construction, the slope face should be trackwalked, compacted and vegetated, or provided with other physical means to guard against erosion. Final grades at the top of the slopes must promote surface drainage away from the slope crest. Water must not be allowed to flow in an uncontrolled fashion over the slope face. If it is necessary to direct surface runoff towards the slope, it should be controlled at the top of the slope, piped in a closed conduit installed on the slope face, and taken to an appropriate point of discharge beyond the toe of the slope. All fill placed for slope construction should meet the structural fill requirements as described in Section 5.2.5. 5.2.7 WET WEATHER CONSTRUCTION CONSIDERATIONS RGI recommends that preparation for site grading and construction include procedures intended to drain ponded water, control surface water runoff, and to collect shallow subsurface seepage zones in excavations where encountered. It will not be possible to successfully compact the subgrade or utilize on-site soils as structural fill if accumulated water is not drained prior to grading or if drainage is not controlled during construction. Attempting to grade the site without adequate drainage control measures will reduce the amount of on-site soil effectively available for use, increase the amount of select import fill materials required, and ultimately increase the cost of the earthwork phases of the project. Free water should not be allowed to pond on the subgrade soils. RGI anticipates that the use of berms and shallow drainage ditches, with sumps and pumps in utility trenches, will be required for surface water control during wet weather and/or wet site conditions. 5.3 FOUNDATIONS Following site preparation and grading, the proposed building foundation can be supported on conventional spread footings bearing on dense native soil or structural fill. Loose, organic, or other unsuitable soils may be encountered in the proposed building footprint. If unsuitable soils are encountered, they should be overexcavated and backfilled with structural fill. Perimeter foundations exposed to weather should be at a minimum depth of 18 inches below final exterior grades. Interior foundations can be constructed at any convenient depth below the floor slab. Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings. Geotechnical Engineering Report 10 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 Table 4 Foundation Design Design Parameter Value Allowable Bearing Capacity - Structural Fill 2,500 psf1 Friction Coefficient 0.30 Passive pressure (equivalent fluid pressure) 250 pcf2 Minimum foundation dimensions Columns: 24 inches Walls: 16 inches 1. psf = pounds per square foot 2. pcf = pounds per cubic foot The allowable foundation bearing pressures apply to dead loads plus design live load conditions. For short-term loads, such as wind and seismic, a 1/3 increase in this allowable capacity may be used. At perimeter locations, RGI recommends not including the upper 12 inches of soil in the computation of passive pressures because they can be affected by weather or disturbed by future grading activity. The passive pressure value assumes the foundation will be constructed neat against competent soil or backfilled with structural fill as described in Section 5.2.5. The recommended base friction and passive resistance value includes a safety factor of about 1.5. With spread footing foundations designed in accordance with the recommendations in this section, maximum total and differential post-construction settlements of 1 inch and 1/2 inch, respectively, should be expected. 5.4 RETAINING WALLS If retaining walls are needed for the future residences or within the detention pond, RGI recommends cast-in-place concrete walls be used. If grade changes are necessary in lot or landscape areas, modular block walls can be used. RGI can provide design for modular block walls once the configuration and height of the walls has been determined. 5.4.1 CAST-IN-PLACE WALLS The magnitude of earth pressure development on retaining walls will partly depend on the quality of the wall backfill. RGI recommends placing and compacting wall backfill as structural fill. Wall drainage will be needed behind the wall face. A typical retaining wall drainage detail is shown in Figure 3. The perforated pipe shown in the detail may be replaced with 2 inch diameter weep holes through the wall at 10 foot centers approximately 6 inches above the wetpond or finished landscape surface for walls in the detention pond or landscape areas. Geotechnical Engineering Report 11 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 With wall backfill placed and compacted as recommended, and drainage properly installed, RGI recommends using the values in the following table for design. Table 5 Retaining Wall Design Design Parameter Value Allowable Bearing Capacity - Structural Fill 2,500 psf Active Earth Pressure (unrestrained walls) 35 pcf At-rest Earth Pressure (restrained walls) 50 pcf For seismic design, an additional uniform load of 7 times the wall height (H) for unrestrained walls and 14H for restrained walls should be applied to the wall surface. Friction at the base of foundations and passive earth pressure will provide resistance to these lateral loads. Values for these parameters are provided in Section 5.3. 5.5 SLAB-ON-GRADE CONSTRUCTION Once site preparation has been completed as described in Section 5.2, suitable support for slab-on-grade construction should be provided. RGI recommends that the concrete slab be placed on top of medium dense native soil or structural fill. Immediately below the floor slab, RGI recommends placing a four-inch thick capillary break layer of clean, free-draining sand or gravel that has less than five percent passing the U.S. No. 200 sieve. This material will reduce the potential for upward capillary movement of water through the underlying soil and subsequent wetting of the floor slab. Where moisture by vapor transmission is undesirable, an 8- to 10-millimeter thick plastic membrane should be placed on a 4-inch thick layer of clean gravel. For the anticipated floor slab loading, we estimate post-construction floor settlements of 1/4- to 1/2-inch. 5.6 DRAINAGE 5.6.1 SURFACE Final exterior grades should promote free and positive drainage away from the building area. Water must not be allowed to pond or collect adjacent to foundations or within the immediate building area. For non-pavement locations, RGI recommends providing a minimum drainage gradient of 3 percent for a minimum distance of 10 feet from the building perimeter. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. Geotechnical Engineering Report 12 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 5.6.2 SUBSURFACE RGI recommends installing perimeter foundation drains. A typical footing drain detail is shown on Figure 4. The foundation drains and roof downspouts should be tightlined separately to an approved discharge facility. Subsurface drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved discharge. 5.6.3 INFILTRATION The site soils consist of weathered glacial till underlain by very dense unweather glacial till. Iron oxide staining was observed at the interface of the unweathered till indicative of a shallow seasonal perched groundwater table. Based on the soil conditions the site is not suitable for infiltration. 5.7 UTILITIES Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the right-of-ways, bedding and backfill should be completed in accordance with King County specifications. At a minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2.5. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil’s maximum density as determined by the referenced ASTM D1557. As noted, soils excavated on site will not be suitable for use as backfill material in wet weather. Imported structural fill meeting the gradation provided in Table 2 may be necessary for trench backfill. The native soils should be suitable for use as backfill material in the summer and fall months in dry weather, however moisture condition of the soils should be expected. 5.8 PAVEMENTS Pavement subgrades should be prepared as described in Section 5.2 and as discussed below. Regardless of the relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proofrolled with heavy construction equipment to verify this condition. With the pavement subgrade prepared as described above, RGI recommends the following pavement sections in accordance with the preferred section in the King County Road Design and Construction Standards - 2007: ¾ For Residential Streets: 2 inches of Class ½ inch Hot Mix Asphalt (HMA) over 4 inches of Class ¾ or 1 inch HMA The asphalt paving materials used should conform to the Washington State Department of Transportation (WSDOT) specifications for HMA surfacing. Geotechnical Engineering Report 13 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 Long-term pavement performance will depend on surface drainage. A poorly-drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance, surface drainage gradients of no less than 2 percent are recommended. Also, some degree of longitudinal and transverse cracking of the pavement surface should be expected over time. Regular maintenance should be planned to seal cracks when they occur. 6.0 Additional Services RGI is available to provide further geotechnical consultation throughout the design phase of the project. RGI should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated into project design and construction. RGI is also available to provide geotechnical engineering and construction monitoring services during construction. The integrity of the earthwork and construction depends on proper site preparation and procedures. In addition, engineering decisions may arise in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this scope of work. If these services are desired, please let us know and we will prepare a cost proposal. 7.0 Limitations This GER is the property of RGI, Nordic Ridge, LLC, and its designated agents. Within the limits of the scope and budget, this GER was prepared in accordance with generally accepted geotechnical engineering practices in the area at the time this GER was issued. This GER is intended for specific application to the Nordic Ridge Plat project in Renton, Washington, and for the exclusive use of Nordic Ridge, LLC and its authorized representatives. No other warranty, expressed or implied, is made. Site safety, excavation support, and dewatering requirements are the responsibility of others. The scope of services for this project does not include either specifically or by implication any environmental or biological (for example, mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, we can provide a proposal for these services. The analyses and recommendations presented in this GER are based upon data obtained from the test exploration performed on site. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, RGI should be requested to reevaluate the recommendations in this GER prior to proceeding with construction. Geotechnical Engineering Report 14 July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 It is the client’s responsibility to see that all parties to the project, including the designers, contractors, subcontractors, are made aware of this GER in its entirety. The use of information contained in this GER for bidding purposes should be done at the contractor’s option and risk. USGS, 1994, Renton, Washington 7.5-Minute Quadrangle Approximate Scale: 1"=1000' 0 500 1000 2000 N Site Vicinity Map Figure 1 07/2015 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Nordic Ridge Plat (Wells Property) RGI Project Number 2015-097 Date Drawn: Address: 17709 116th Avenue Southeast, Renton, Washington 98058 SITE TP-7 TP-6 TP-8 TP-5 TP-4 TP-3 TP-2 TP-1 N Geotechnical Exploration Plan Figure 2 Approximate Scale: 1"=100' 0 50 100 200 = Test Pit Location by RGI on 07/01/15 Drawn from ESM Consulting Engineers LLC, Preliminary Plat Plan PP-01. 07/2015 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Nordic Ridge Plat (Wells Property) RGI Project Number 2015-097 Date Drawn: Address: 17709 116th Avenue Southeast, Renton, Washington 98058 Incliniations) 12" Over the Pipe 3" Below the Pipe Perforated Pipe 4" Diameter PVC Compacted Structural Backfill (Native or Import) 12" min. Filter Fabric Material 12" Minimum Wide Free-Draining Gravel Slope to Drain (See Report for Appropriate Excavated Slope 07/2015 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Nordic Ridge Plat (Wells Property) RGI Project Number 2015-097 Date Drawn: Address: 17709 116th Avenue Southeast, Renton, Washington 98058 Retaining Wall Drainage Detail Figure 3 Not to Scale 3/4" Washed Rock or Pea Gravel 4" Perforated Pipe Building Slab Structural Backfill Compacted Filter Fabric 07/2015 Corporate Office 17522 Bothell Way Northeast Bothell, Washington 98011 Phone: 425.415.0551 Fax: 425.415.0311 Nordic Ridge Plat (Wells Property) RGI Project Number 2015-097 Date Drawn: Address: 17709 116th Avenue Southeast, Renton, Washington 98058 Typical Footing Drain Detail Figure 4 Not to Scale Geotechnical Engineering Report July 8, 2015 Nordic Ridge Plat, Renton, Washington RGI Project No. 2015-097 APPENDIX A FIELD EXPLORATION AND LABORATORY TESTING On July 1, 2015, RGI performed field explorations using a rubber tired backhoe. We explored subsurface soil conditions at the site by observing the excavation of eight test pits to a maximum depth of 8 feet below existing grade. The test pits locations are shown on Figure 2. The test pits locations were approximately determined by measurements from existing property lines and paved roads. A geologist from our office conducted the field exploration and classified the soil conditions encountered, maintained a log of each test exploration, obtained representative soil samples, and observed pertinent site features. All soil samples were visually classified in accordance with the Unified Soil Classification System (USCS). Representative soil samples obtained from the explorations were placed in closed containers and taken to our laboratory for further examination and testing. As a part of the laboratory testing program, the soil samples were classified in our in house laboratory based on visual observation, texture, plasticity, and the limited laboratory testing described below. Moisture Content Determinations Moisture content determinations were performed in accordance with ASTM D2216-10 Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass (ASTM D2216) on representative samples obtained from the exploration in order to aid in identification and correlation of soil types. The moisture content of typical sample was measured and is reported on the test pits Logs. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses was determined using D6913-04(2009) Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis (ASTM D6913) on three of the samples. Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-1 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:8 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 16% moisture, 24% fines 16% moisture 10% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with some gravel, loose to medium dense, moist Gray silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, dense to very dense, moist (Glacial Till) Becomes very dense Test Pit terminated at 8'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-2 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:7 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 14% moisture 11% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test pit terminated at 7'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-3 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:7 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 11% moisture 14% moisture 10% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test Pit terminated at 7'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-4 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:7.5 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 9% moisture 15% moisture 12% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test Pit terminated at 7.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-5 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:6.5 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 9% moisture 11% moisture 12% moisture, 35% finesGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with trace gravel, very dense, moist (Glacial Till) Test Pit terminated at 6.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-6 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:6 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 11% moisture 12% moisture 12% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test Pit terminated at 6'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-7 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:8 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 10% moisture 10% moisture, 20% fines 12% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Gray silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test Pit terminated at 8'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Test Pit No.: TP-8 Date(s) Excavated:7/1/2015 Excavation Method:Backhoe Excavator Type:Rubber Tire Backhoe Groundwater Level:Not Encountered Test Pit Backfill:Cuttings Logged By ELW Bucket Size:N/A Excavating Contractor:Harbor Point Excavating Sampling Method(s)Grab Location 17709 116th Avenue Southeast, Renton, Washington Surface Conditions:Grass Total Depth of Excavation:6.5 feet bgs Approximate Surface Elevation Compaction Method Bucket USCS SymbolTPSL SM SM SM REMARKS AND OTHER TESTS 9% moisture 13% moisture 11% moistureGraphic LogMATERIAL DESCRIPTION Topsoil Brown silty SAND with trace gravel, loose to medium dense, moist Brown silty SAND with some gravel, medium dense to dense, moist (Weathered Till) Iron oxide staining Gray silty SAND with some gravel, very dense, moist (Glacial Till) Test Pit terminated at 6.5'Depth (feet)0 5 10 Sample NumberSample TypeElevation (feet)Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 Project Name:Nordic Ridge Plat Project Number:2015-097 Client:Nordic Ridge, LLC Key to Logs USCS SymbolREMARKS AND OTHER TESTSGraphic LogMATERIAL DESCRIPTIONDepth (feet)Sample NumberSample TypeElevation (feet)1 2 3 4 5 6 7 8 COLUMN DESCRIPTIONS 1 Elevation (feet): Elevation (MSL, feet). 2 Depth (feet): Depth in feet below the ground surface. 3 Sample Type: Type of soil sample collected at the depth interval shown. 4 Sample Number: Sample identification number. 5 USCS Symbol: USCS symbol of the subsurface material. 6 Graphic Log: Graphic depiction of the subsurface material encountered. 7 MATERIAL DESCRIPTION: Description of material encountered. May include consistency, moisture, color, and other descriptive text. 8 REMARKS AND OTHER TESTS: Comments and observations regarding drilling or sampling made by driller or field personnel. FIELD AND LABORATORY TEST ABBREVIATIONS CHEM: Chemical tests to assess corrosivity COMP: Compaction test CONS: One-dimensional consolidation test LL: Liquid Limit, percent PI: Plasticity Index, percent SA: Sieve analysis (percent passing No. 200 Sieve) UC: Unconfined compressive strength test, Qu, in ksf WA: Wash sieve (percent passing No. 200 Sieve) MATERIAL GRAPHIC SYMBOLS Silty SAND (SM) TYPICAL SAMPLER GRAPHIC SYMBOLS Auger sampler Bulk Sample 3-inch-OD California w/ brass rings CME Sampler Grab Sample 2.5-inch-OD Modified California w/ brass liners Pitcher Sample 2-inch-OD unlined split spoon (SPT) Shelby Tube (Thin-walled, fixed head) OTHER GRAPHIC SYMBOLS Water level (at time of drilling, ATD) Water level (after waiting) Minor change in material properties within a stratum Inferred/gradational contact between strata ?Queried contact between strata GENERAL NOTES 1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be gradual. Field descriptions may have been modified to reflect results of lab tests. 2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative of subsurface conditions at other locations or times. Sheet 1 of 1 The Riley Group, Inc. 17522 Bothell Way NE, Bothell, WA 98011 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Nordic Ridge Plat SAMPLE ID/TYPE TP-1 PROJECT NO.2015-097 SAMPLE DEPTH 2' TECH/TEST DATE ELW 7/1/2015 DATE RECEIVED 7/1/2015 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)391.8 Weight Of Sample (gm)339.2 Wt Dry Soil & Tare (gm)(w2)339.2 Tare Weight (gm) 15.6 Weight of Tare (gm)(w3)15.6 (W6) Total Dry Weight (gm)323.6 Weight of Water (gm)(w4=w1-w2)52.6 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3)323.6 Cumulative Moisture Content (%) (w4/w5)*100 16 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"15.6 0.00 0.00 100.00 cobbles % C GRAVEL 0.0 3.0"15.6 0.00 0.00 100.00 coarse gravel % F GRAVEL 19.1 2.5" coarse gravel % C SAND 9.4 2.0" coarse gravel % M SAND 19.1 1.5"15.6 0.00 0.00 100.00 coarse gravel % F SAND 28.6 1.0" coarse gravel % FINES 23.8 0.75"15.6 0.00 0.00 100.00 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"51.9 36.30 11.22 88.78 fine gravel D10 (mm)#4 77.4 61.80 19.10 80.90 coarse sand D30 (mm)#10 107.9 92.30 28.52 71.48 medium sand D60 (mm)#20 medium sand Cu #40 169.7 154.10 47.62 52.38 fine sand Cc #60 fine sand #100 240.9 225.30 69.62 30.38 fine sand #200 262.1 246.50 76.17 23.83 fines PAN 339.2 323.60 100.00 0.00 silt/clay DESCRIPTION Silty SAND with some gravel USCS SM Prepared For:Reviewed By:KMW Nordic Ridge, LLC 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3"2"1".75".375"#4 #10 #20 #40 #60 #100 #200 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Nordic Ridge Plat SAMPLE ID/TYPE TP-5 PROJECT NO.2015-097 SAMPLE DEPTH 5' TECH/TEST DATE ELW 7/1/2015 DATE RECEIVED 7/1/2015 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)490.4 Weight Of Sample (gm)439.0 Wt Dry Soil & Tare (gm)(w2)439.0 Tare Weight (gm) 15.4 Weight of Tare (gm)(w3)15.4 (W6) Total Dry Weight (gm)423.6 Weight of Water (gm)(w4=w1-w2)51.4 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3)423.6 Cumulative Moisture Content (%) (w4/w5)*100 12 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"15.4 0.00 0.00 100.00 cobbles % C GRAVEL 7.0 3.0"15.4 0.00 0.00 100.00 coarse gravel % F GRAVEL 4.5 2.5" coarse gravel % C SAND 3.0 2.0" coarse gravel % M SAND 10.7 1.5"15.4 0.00 0.00 100.00 coarse gravel % F SAND 40.3 1.0" coarse gravel % FINES 34.5 0.75"45.0 29.60 6.99 93.01 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"56.9 41.50 9.80 90.20 fine gravel D10 (mm)#4 64.0 48.60 11.47 88.53 coarse sand D30 (mm)#10 76.6 61.20 14.45 85.55 medium sand D60 (mm)#20 medium sand Cu #40 122.0 106.60 25.17 74.83 fine sand Cc #60 fine sand #100 257.1 241.70 57.06 42.94 fine sand #200 292.9 277.50 65.51 34.49 fines PAN 439.0 423.60 100.00 0.00 silt/clay DESCRIPTION Silty SAND with trace gravel USCS SM Prepared For:Reviewed By:KMW Nordic Ridge, LLC 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3"2"1".75".375"#4 #10 #20 #40 #60 #100 #200 THE RILEY GROUP, INC. 17522 Bothell Way NE Bothell, WA 98011 PHONE: (425) 415-0551 FAX: (425) 415-0311 GRAIN SIZE ANALYSIS ASTM D421, D422, D1140, D2487, D6913 PROJECT TITLE Nordic Ridge Plat SAMPLE ID/TYPE TP-7 PROJECT NO.2015-097 SAMPLE DEPTH 4' TECH/TEST DATE ELW 7/1/2015 DATE RECEIVED 7/1/2015 WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture Wt Wet Soil & Tare (gm) (w1)329.5 Weight Of Sample (gm)300.7 Wt Dry Soil & Tare (gm)(w2)300.7 Tare Weight (gm) 15.6 Weight of Tare (gm)(w3)15.6 (W6) Total Dry Weight (gm)285.1 Weight of Water (gm)(w4=w1-w2)28.8 SIEVE ANALYSIS Weight of Dry Soil (gm) (w5=w2-w3)285.1 Cumulative Moisture Content (%) (w4/w5)*100 10 Wt Ret (Wt-Tare) (%Retained)% PASS +Tare {(wt ret/w6)*100}(100-%ret) % COBBLES 0.0 12.0"15.6 0.00 0.00 100.00 cobbles % C GRAVEL 12.1 3.0"15.6 0.00 0.00 100.00 coarse gravel % F GRAVEL 13.3 2.5" coarse gravel % C SAND 7.4 2.0" coarse gravel % M SAND 17.4 1.5"15.6 0.00 0.00 100.00 coarse gravel % F SAND 29.5 1.0" coarse gravel % FINES 20.3 0.75"50.0 34.40 12.07 87.93 fine gravel % TOTAL 100.0 0.50" fine gravel 0.375"68.3 52.70 18.48 81.52 fine gravel D10 (mm)#4 87.9 72.30 25.36 74.64 coarse sand D30 (mm)#10 109.0 93.40 32.76 67.24 medium sand D60 (mm)#20 medium sand Cu #40 158.7 143.10 50.19 49.81 fine sand Cc #60 fine sand #100 223.5 207.90 72.92 27.08 fine sand #200 242.8 227.20 79.69 20.31 fines PAN 300.7 285.10 100.00 0.00 silt/clay DESCRIPTION Silty SAND with some gravel USCS SM Prepared For:Reviewed By:KMW Nordic Ridge, LLC 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 % P A S S I N G Grain size in millimeters 12"3"2"1".75".375"#4 #10 #20 #40 #60 #100 #200 33 7. OTHER PERMITS The National Pollutant Discharge Elimination System (NPDES) permit will be applied for online, as the project gets closer to construction. This project will also require the following permits: Building Permits Clearing & Grading Permits 35 8.CSWPPP ANALYSIS AND DESIGN The Temporary Erosion and Sedimentation Control (TESC) Plan is shown on sheets GR-01 through GR-03 of the plan set. The TESC Plan was developed in accordance with criteria in Section 1.2.5 and Appendix D of the 2009 Surface Water Design Manual. One sediment drainage basin was used with a sediment pond placed at the same location as the permanent combined detention/water quality pond. The sediment pond was located on the northeast side of the project, to match existing topography with the intent of preventing to the maximum extent possible, the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties. The soils and hydrology of the proposed project site are described in Section 4. The 15- minute peak discharge from the 2 year storm event was used to size the sediment pond, to provide as additional protection during construction for the downstream areas. Table 6 is a summary of the sediment pond drainage basin hydrology calculations. The sediment pond has been sized with 3:1 side slopes, 1.5 feet of sediment storage depth, 4.5 feet of settling depth, a 1 foot of overflow depth to the top of the riser and an additional 1 foot overflow depth to the top of the emergency overflow spillway. TABLE 8.1 Developed Bypass Area Sediment Basin Characteristics Area (ac) 2 year Peak Flow (cfs) Trap Surface Area (sf) Bottom Dimensions (ft) Sediment Basin 3.76 1.15 2396 43x80 Detailed calculations are attached following this section. A Stormwater Pollution Prevention Plan (SWPPP), has been completed under separate cover. Kinkade Crossing Temporary Erosion and Sediment Control Plan (TESCP) Sediment Pond Parameters Developed Basin Maximum basin contributing area (acres)3.76 Settling Velocity (feet/second)0.00096 Sediment Storage (feet)1.5 Settling Depth, Riser Height (feet)3.5 Freeboard to Overflow (feet)1 Overflow (feet)1 Total Depth (feet)7 Orifice Area, A0 (square feet)A0 0.022 2 X {orifice Head || Riser Height} (feet)2h 7 Drawdown Time T (hours)T 24 Accereration due to gravity, g (ft/sec^2)g 32.2 Orifice Diameter, D (inches)D 1.99 Sediment Pond Sizing Developed Basin Facility Top Elev.460.5 Width at Top of Sed. Stor. Length at Top of Sed. Stor. Settling Depth (feet)3.5 Impervious Contributing Area (acres) Pervious Contributing Area (acres) Total Contributing Area (acres)3.76 Developed 10 year Flow, 15-minute timesteps (cfs)1.15 Design Surface Area (square feet)SA 2396 Trap Surface Area (square feet)As 2396 kinkadetesc.pks Flow Frequency Analysis Time Series File:kinkadetesc.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 1.15 6 8/27/01 18:00 3.53 1 100.00 0.990 0.817 8 1/05/02 15:00 2.47 2 25.00 0.960 2.47 2 12/08/02 17:15 1.61 3 10.00 0.900 0.928 7 8/23/04 14:30 1.41 4 5.00 0.800 1.41 4 11/17/04 5:00 1.38 5 3.00 0.667 1.38 5 10/27/05 10:45 1.15 6 2.00 0.500 1.61 3 10/25/06 22:45 0.928 7 1.30 0.231 3.53 1 1/09/08 6:30 0.817 8 1.10 0.091 Computed Peaks 3.18 50.00 0.980 Page 1 35 9.BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT The Site Improvement Bond Quantity Worksheet is attached following this page. Site Improvement Bond Quantity WorksheetS15 Web date: 04/03/2015 Department of Permitting & Environmental Review35030 SE Douglas Street, Suite 210Snoqualmie, Washington 98065-9266206-296-6600 TTY Relay 711Project Name: Date: Location: Project No.: Activity No.: Note: All prices include labor, equipment, materials, overhead and Clearing greater than or equal to 5,000 board feet of timber? profit. Prices are from RS Means data adjusted for the Seattle area or from local sources if not included in the RS Means database._____________yes __________________no If yes, Forest Practice Permit Number: (RCW 76.09)Page 1 of 9Kinkade Crossing17709 116th Avenue SE, Renton WAFor alternate formats, call 206-296-6600. __________________5/25/2016li-wks-sbqxls.xlsUnit prices updated: 3/2/2015 Version: 3/2/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetS15 Web date: 04/03/2015 Unit# ofReference # Price Unit Quantity Applications CostEROSION/SEDIMENT CONTROLNumberBackfill & compaction-embankmentESC-16.00$ CY 5820 134920Check dams, 4" minus rockESC-2SWDM 5.4.6.3 80.00$ EachCrushed surfacing 1 1/4" minusESC-3WSDOT 9-03.9(3) 95.00$ CYDitchingESC-49.00$ CY 676 16084Excavation-bulkESC-52.00$ CY 5666 111332Fence, siltESC-6SWDM 5.4.3.1 1.50$ LF 1536 12304Fence, Temporary (NGPE)ESC-71.50$ LFHydroseedingESC-8SWDM 5.4.2.4 0.80$ SY 12695 110156Jute MeshESC-9SWDM 5.4.2.2 3.50$ SYMulch, by hand, straw, 3" deepESC-10SWDM 5.4.2.1 2.50$ SYMulch, by machine, straw, 2" deepESC-11SWDM 5.4.2.1 2.00$ SYPiping, temporary, CPP, 6"ESC-1212.00$ LFPiping, temporary, CPP, 8"ESC-1314.00$ LFPiping, temporary, CPP, 12"ESC-1418.00$ LFPlastic covering, 6mm thick, sandbaggedESC-15SWDM 5.4.2.3 4.00$ SYRip Rap, machine placed; slopesESC-16WSDOT 9-13.1(2) 45.00$ CYRock Construction Entrance, 50'x15'x1'ESC-17SWDM 5.4.4.1 1,800.00$ EachRock Construction Entrance, 100'x15'x1'ESC-18SWDM 5.4.4.1 3,200.00$ Each 2 16400Sediment pond riser assemblyESC-19SWDM 5.4.5.2 2,200.00$ Each 1 12200Sediment trap, 5' high berm ESC-20SWDM 5.4.5.1 19.00$ LFSed. trap, 5' high, riprapped spillway berm section ESC-21SWDM 5.4.5.1 70.00$ LFSeeding, by handESC-22SWDM 5.4.2.4 1.00$ SYSodding, 1" deep, level groundESC-23SWDM 5.4.2.5 8.00$ SYSodding, 1" deep, sloped groundESC-24SWDM 5.4.2.5 10.00$ SYTESC SupervisorESC-25110.00$ HRWater truck, dust controlESC-26SWDM 5.4.7 140.00$ HRWRITE-IN-ITEMS **** (see page 9)EachESC SUBTOTAL:73,396.00$ 30% CONTINGENCY & MOBILIZATION:22,018.80$ ESC TOTAL:95,414.80$ COLUMN: Ali-wks-sbqxls.xlsUnit prices updated: 3/2/2015 Version: 3/2/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetS15 Web date: 04/03/2015 Page 2 of 9li-wks-sbqxls.xlsUnit prices updated: 3/2/2015 Version: 3/2/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future Public PrivateRight-of-Way Right of Way ImprovementsUnit Price Unit Quant. Cost Quant. Cost Quant. CostGENERAL ITEMSNo.Backfill & Compaction- embankment GI - 1 6.00$ CY5820 34,920.00Backfill & Compaction- trench GI - 2 9.00$ CYClear/Remove Brush, by hand GI - 3 1.00$ SYClearing/Grubbing/Tree Removal GI - 4 10,000.00$ Acre3.6 36,000.00Excavation - bulk GI - 5 2.00$ CY5666 11,332.00Excavation - Trench GI - 6 5.00$ CYFencing, cedar, 6' high GI - 7 20.00$ LFFencing, chain link, vinyl coated, 6' high GI - 8 20.00$ LF503 10,060.00Fencing, chain link, gate, vinyl coated, 20' GI - 9 1,400.00$ Each1 1,400.00Fencing, split rail, 3' high GI - 10 15.00$ LFFill & compact - common barrow GI - 11 25.00$ CYFill & compact - gravel base GI - 12 27.00$ CYFill & compact - screened topsoil GI - 13 39.00$ CYGabion, 12" deep, stone filled mesh GI - 14 65.00$ SYGabion, 18" deep, stone filled mesh GI - 15 90.00$ SYGabion, 36" deep, stone filled mesh GI - 16 150.00$ SYGrading, fine, by hand GI - 17 2.50$ SYGrading, fine, with grader GI - 18 2.00$ SY 387 774.00 4686 9,372.00Monuments, 3' long GI - 19 250.00$ Each 1 250.00 3 750.00Sensitive Areas Sign GI - 20 7.00$ EachSodding, 1" deep, sloped ground GI - 21 8.00$ SYSurveying, line & grade GI - 22 850.00$ DaySurveying, lot location/lines GI - 23 1,800.00$ AcreTraffic control crew ( 2 flaggers ) GI - 24 120.00$ HRTrail, 4" chipped wood GI - 25 8.00$ SYTrail, 4" crushed cinder GI - 26 9.00$ SYTrail, 4" top course GI - 27 12.00$ SYWall, retaining, concrete GI - 28 55.00$ SF2472 135,960.00Wall, rockery GI - 29 15.00$ SF973 14,595.00Page 3 of 9SUBTOTAL 1,024.00 239,794.00 14,595.00 & Drainage Facilities*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future PublicRight-of-way Right of Way ImprovementsUnit Price Unit Quant. Cost Quant. Cost Quant. CostROAD IMPROVEMENTNo.AC Grinding, 4' wide machine < 1000sy RI - 1 30.00$ SYAC Grinding, 4' wide machine 1000-2000syRI - 2 16.00$ SYAC Grinding, 4' wide machine > 2000sy RI - 3 10.00$ SYAC Removal/Disposal RI - 4 35.00$ SY 234 8,190.00Barricade, type III ( Permanent ) RI - 6 56.00$ LFCurb & Gutter, rolled RI - 7 17.00$ LFCurb & Gutter, vertical RI - 8 12.50$ LF 283 3,537.50 1468 18,350.00Curb and Gutter, demolition and disposal RI - 9 18.00$ LFCurb, extruded asphalt RI - 10 5.50$ LFCurb, extruded concrete RI - 11 7.00$ LFSawcut, asphalt, 3" depth RI - 12 1.85$ LF 653 1,208.05Sawcut, concrete, per 1" depth RI - 13 3.00$ LFSealant, asphalt RI - 14 2.00$ LFShoulder, AC, ( see AC road unit price ) RI - 15 -$ SYShoulder, gravel, 4" thick RI - 16 15.00$ SYSidewalk, 4" thick RI - 17 38.00$ SY1170 44,460.00Sidewalk, 4" thick, demolition and disposalRI - 18 32.00$ SYSidewalk, 5" thick RI - 19 41.00$ SYSidewalk, 5" thick, demolition and disposalRI - 20 40.00$ SYSign, handicap RI - 21 85.00$ EachStriping, per stall RI - 22 7.00$ EachStriping, thermoplastic, ( for crosswalk ) RI - 23 3.00$ SFStriping, 4" reflectorized line RI - 24 0.50$ LFPage 4 of 9SUBTOTAL 12,935.55 62,810.00Private & Drainage Facilities*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future Public PrivateRight-of-way Right of Way ImprovementsUnit Price Unit Quant. Cost Quant. Cost Quant. CostROAD SURFACING No. (4" Rock = 2.5 base & 1.5" top course) 9 1/2" Rock= 8" base & 1.5" top course)Additional 2.5" Crushed Surfacing RS - 1 3.60$ SYHMA 1/2" Overlay, 1.5" RS - 2 14.00$ SYHMA 1/2" Overlay 2" RS - 3 18.00$ SYHMA Road, 2", 4" rock, First 2500 SY RS - 4 28.00$ SY 294 8,232.00 2253 63,084.00HMA Road, 2", 4" rock, Qty. over 2500 SYRS - 5 21.00$ SYHMA Road, 3", 9 1/2" Rock, First 2500 SYRS - 6 35.00$ SYHMA Road, 3", 9 1/2" Rock, Qty Over 2500 SYRS - 7 42.00$ SYNot Used RS - 8Not Used RS - 9HMA Road, 6" Depth, First 2500 SY RS - 10 33.10$ SYHMA Road, 6" Depth, Qty. Over 2500 SY RS - 11 30.00$ SYHMA 3/4" or 1", 4" Depth RS - 12 20.00$ SYGravel Road, 4" rock, First 2500 SY RS - 13 15.00$ SYGravel Road, 4" rock, Qty. over 2500 SY RS - 14 10.00$ SYPCC Road (Add Under Write-Ins w/Design) RS - 15Thickened Edge RS - 17 8.60$ LFPage 5 of 9SUBTOTAL 8,232.00 63,084.00 & Drainage Facilities*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future Public PrivateRight-of-way Right of Way ImprovementsUnit Price Unit Quant. Cost Quant. Cost Quant. CostDRAINAGE (CPP = Corrugated Plastic Pipe, N12 or Equivalent)Access Road, R/D D - 1 21.00$ SY172 3,612.00Bollards - fixed D - 2 240.74$ EachBollards - removable D - 3 452.34$ Each* (CBs include frame and lid)CB Type I D - 4 1,500.00$ Each 1 1,500.00 6 9,000.00CB Type IL D - 5 1,750.00$ Each2 3,500.00CB Type II, 48" diameter D - 6 2,300.00$ Each 1 2,300.00 10 23,000.00 for additional depth over 4' D - 7 480.00$ FT33 15,840.00CB Type II, 54" diameter D - 8 2,500.00$ Each for additional depth over 4' D - 9 495.00$ FTCB Type II, 60" diameter D - 10 2,800.00$ Each1 2,800.00 for additional depth over 4' D - 11 600.00$ FT4 2,400.00CB Type II, 72" diameter D - 12 3,600.00$ Each for additional depth over 4' D - 13 850.00$ FTThrough-curb Inlet Framework (Add) D - 14 400.00$ Each5 2,000.00Cleanout, PVC, 4" D - 15 150.00$ EachCleanout, PVC, 6" D - 16 170.00$ Each16 2,720.00Cleanout, PVC, 8" D - 17 200.00$ EachCulvert, PVC, 4" D - 18 10.00$ LFCulvert, PVC, 6" D - 19 13.00$ LF771 10,023.00Culvert, PVC, 8" D - 20 15.00$ LFCulvert, PVC, 12" D - 21 23.00$ LFCulvert, CMP, 8" D - 22 19.00$ LFCulvert, CMP, 12" D - 23 29.00$ LF1054 30,566.00Culvert, CMP, 15" D - 24 35.00$ LFCulvert, CMP, 18" D - 25 41.00$ LFCulvert, CMP, 24" D - 26 56.00$ LFCulvert, CMP, 30" D - 27 78.00$ LFCulvert, CMP, 36" D - 28 130.00$ LFCulvert, CMP, 48" D - 29 190.00$ LFCulvert, CMP, 60" D - 30 270.00$ LFCulvert, CMP, 72" D - 31 350.00$ LFPage 6 of 9SUBTOTAL 3,800.00 92,718.00 12,743.00 & Drainage Facilities For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future Public PrivateRight-of-way Right of Way ImprovementsDRAINAGE CONTINUEDNo. Unit Price Unit Quant. Cost Quant. Cost Quant. CostCulvert, Concrete, 8" D - 32 25.00$ LFCulvert, Concrete, 12" D - 33 36.00$ LFCulvert, Concrete, 15" D - 34 42.00$ LFCulvert, Concrete, 18" D - 35 48.00$ LFCulvert, Concrete, 24" D - 36 78.00$ LFCulvert, Concrete, 30" D - 37 125.00$ LFCulvert, Concrete, 36" D - 38 150.00$ LFCulvert, Concrete, 42" D - 39 175.00$ LFCulvert, Concrete, 48" D - 40 205.00$ LFCulvert, CPP, 6" D - 41 14.00$ LFCulvert, CPP, 8" D - 42 16.00$ LFCulvert, CPP, 12" D - 43 24.00$ LFCulvert, CPP, 15" D - 44 35.00$ LFCulvert, CPP, 18" D - 45 41.00$ LFCulvert, CPP, 24" D - 46 56.00$ LFCulvert, CPP, 30" D - 47 78.00$ LFCulvert, CPP, 36" D - 48 130.00$ LFDitching D - 49 9.50$ CYFlow Dispersal Trench (1,436 base+) D - 50 28.00$ LFFrench Drain (3' depth) D - 51 26.00$ LFGeotextile, laid in trench, polypropylene D - 52 3.00$ SYMid-tank Access Riser, 48" dia, 6' deep D - 54 2,000.00$ EachPond Overflow Spillway D - 55 16.00$ SYRestrictor/Oil Separator, 12" D - 56 1,150.00$ Each1 1150Restrictor/Oil Separator, 15" D - 57 1,350.00$ EachRestrictor/Oil Separator, 18" D - 58 1,700.00$ EachRiprap, placed D - 59 42.00$ CYTank End Reducer (36" diameter) D - 60 1,200.00$ EachTrash Rack, 12" D - 61 350.00$ Each2 700Trash Rack, 15" D - 62 410.00$ Each1 410Trash Rack, 18" D - 63 480.00$ EachTrash Rack, 21" D - 64 550.00$ EachPage 7 of 9SUBTOTAL2260 & Drainage Facilities*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Existing Future Public PrivateRight-of-way Right of Way ImprovementsUnit Price Unit Quant. Price Quant. Cost Quant. CostPARKING LOT SURFACINGNo.2" AC, 2" top course rock & 4" borrow PL - 1 21.00$ SY NA NA2" AC, 1.5" top course & 2.5" base coursePL - 2 28.00$ SY NA NA4" select borrow PL - 3 5.00$ SY NA NA1.5" top course rock & 2.5" base course PL - 4 14.00$ SY NA NAUTILITY POLES & STREET LIGHTINGUtility pole relocation costs must be accompanied by Franchise Utility's Cost EstimateUtility Pole(s) Relocation UP-1Street Light Poles w/Luminaires UP-2 EachWRITE-IN-ITEMS(Such as detention/water quality vaults.)No.WI - 1 EachWI - 2 SYWI - 3 CYWI - 4 LFWI - 5 FTWI - 6WI - 7WI - 8WI - 9WI - 10SUBTOTAL SUBTOTAL (SUM ALL PAGES):25,991.55 460,666.00 27,338.0030% CONTINGENCY & MOBILIZATION:7,797.47 138,199.80 8,201.40 GRANDTOTAL: 33,789.02 598,865.80 35,539.40COLUMN: B C DPage 8 of 9Lump Sum & Drainage FacilitiesNot To Be Used For Roads Or Shoulders*KCC 27A authorizes only one bond reduction.li-wks-sbqxls.xlsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 Site Improvement Bond Quantity WorksheetWeb date: 04/03/2015Original bond computations prepared by:Name:Date:PE Registration Number:Tel. #:Firm Name:Address:Project No: Stabilization/Erosion Sediment Control (ESC) (A)Existing Right-of-Way Improvements (B)Future Public Right of Way & Drainage Facilities (C)Private Improvements (D)Calculated Quantity CompletedTotal Right-of Way and/or Site Restoration Bond*/** (A+B)(First $7,500 of bond* shall be cash.)Performance Bond* Amount (A+B+C+D) = TOTAL (T)T x 0.30Minimum is $2000. Minimum is $2000.Maintenance/Defect Bond* TotalMinimum is $2000.NAME OF PERSON PREPARING BOND* REDUCTION:Date:* NOTE:The word "bond" as used in this document means a financial guarantee acceptable to King County.** NOTE: KCC 27A authorizes right of way and site restoration bonds to be combined when both are required. The restoration requirement shall include the total cost for all TESC as a minimum, not a maximum. In addition, corrective work, both on- and off-site needs to be included. Quantities shall reflect worse case scenarios not just minimum requirements. For example, if a salmonid stream may be damaged, some estimated costs for restoration needs to be reflected in this amount. The 30% contingency and mobilization costs are computed in this quantity.*** NOTE: Per KCC 27A, total bond amounts remaining after reduction shall not be less than 30% of the original amount (T) or as revised by major design changes.REQUIRED BOND* AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY KING COUNTY5/25/2016(253) 838-6113 FINANCIAL GUARANTEE REQUIREMENTSPUBLIC ROAD & DRAINAGE MAINTENANCE/DEFECT BOND*Laura Bartenhagen, PEESM Consulting Engineers, LLC33400 8th Avenue South, Suite 205, Federal Way, WA 98003PERFORMANCE BOND*AMOUNT40111MINIMUM BOND* AMOUNT REQUIRED FOR RECORDING ORTEMPORARY OCCUPANCY AT SUBSTANTIAL COMPLETION ***158,163.7$ 95,414.8$ 33,789.0$ 598,865.8$ 229,082.7$ (B+C) x 0.25 =129,203.8$ 35,539.4$ 763,609.0$ Page 9 of 9li-wks-sbqxls.xlsCheck out the DDES Web site at www.kingcounty.gov/permitsUnit prices updated: 03/02/2015Version: 03/02/2015Report Date: 5/25/2016 36 10.OPERATIONS AND MAINTENANCE MANUAL The Operations and Maintenance Manual is provided following this page.