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F_Kinkade Crossing Plat_Technical Information Report_160823
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 Revised August 15, 2016 Job No. 994-001-015 Approved By: City of Renton Date \\esm8\engr\esm-jobs\994\001\015\document\kinkadecrossingtir-2016-08-15.docx 3 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 4.2 Existing Offsite Basin 4 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 by a detention pond and a filter vault located in Tract B, at the northeast corner of the site. Refer to Section 4 for flow control & water quality design details. The stormwater detention 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”. 5 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 6 Figure 1.2 Existing Site Conditions 7 Figure 1.3 Proposed Site Conditions 8 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 0 150 300 600 900Feet 0 50 100 200 300Meters 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 9 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 detention 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 water quality filter vault. See Section 4 for more information. 10 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. 11 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 12 According to the information available on iMap, there have been no downstream drainage complaints in the study area within the last 10 years. 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 No problems with the existing drainage system were observed within the scope of the downstream analysis and no mitigation is proposed. 13 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 15 Figure 3.2 Drainage Complaint Map 16 17 Figure 3.3 Site Topography 18 19 Figure 3.4 Offsite Analysis Downstream Flowpath 20 21 Figure 3.5 Offsite Analysis Drainage System Table 22 Figure 3.6 Picture from Point #1 Looking north along 116th Ave SE 23 Figure 3.7 Picture from Point #2 Looking north along 116th Ave SE The 12” CMP culvert was almost completely covered with vegetation. 24 Figure 3.8 Picture from Point #3 Looking north along 116th Ave SE The 12” CMP culvert was covered with vegetation under the driveway. 25 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. 26 Figure 3.10 Picture from Point #5 Looking west along SE Petrovitsky Road 27 Figure 3.11 Picture from Point #6 Looking east along SE Petrovitsky Road The manhole cover shown in the crosswalk is estimated to be the point of convergence between the 116th Ave SE and SE Petrovitsky Road storm drains. From there it’s piped to Big Soos Creek. 28 Figure 3.12 Picture from Point #7 Looking east along SE Petrovitsky Road The estimated discharge location of the project site’s storm water, approximately 1300 feet downstream of the project site. 29 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 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. This area is represented by the Bypass Basin in Table 4.1 below. There is a significant amount of upstream offsite Right-Of-Way (116th Ave SE) area that drains to the roadside ditch along the west side of 116th Ave SE. See Section 3 for the Offsite Analysis. TABLE 4.1 Pre-Developed Tributary Area TOTAL AREA TILL GRASS IMPERVIOUS (Ac) (Ac) (Ac) Onsite Basin 3.50 3.50 0.00 0.00 Bypass Basin 0.14 0.14 0.00 0.00 Total Onsite 3.64 3.64 0.00 0.00 TOTAL 3.64 3.64 0.00 0.00 SUBBASIN TILL FOREST (Ac) 4.2 Developed Site Hydrology The project will create 17 single family lots with associated roadway, sidewalk, driveways, roof areas, landscaped yards, and a detention pond (flow control facility). All 17 residence lots will have new single-family dwelling units. The areas associated with that development are summarized in the Onsite Basin of Table 4.2. All upstream offsite Right-Of-Way (116th Ave SE) runoff will be collected in a catch basin and piped downstream of the project site and associated flow control facility. A portion of the frontage improvement area will bypass the pond and be treated as bypass area. For more information, see Table 4.3 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 30 10%. Therefore, building rooftops and impervious areas (driveway, porch, patios) are modeled as 55% impervious. The flow control facility is located in the northeastern corner of the site. From there, detained flow will discharge to the east into the existing 116th Ave SE system, which is the site’s natural discharge location. TABLE 4.2 Developed Detained Area TOTAL AREA IMPERVIOUS (Ac) (Ac) Onsite Basin 3.50 1.48 2.02 TOTAL 3.50 1.48 2.02 SUBBASIN TILL GRASS (Ac) TABLE 4.3 Developed Bypass Area TOTAL AREA IMPERVIOUS (Ac) (Ac) Bypass Basin 0.14 0.03 0.11 TOTAL 0.14 0.03 0.11 SUBBASIN TILL GRASS (Ac) 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 PerkFilter vaults located in Tract B, after detention. 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 flow control facility 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 target flows are calculated as follows: 50% 2 year: 50% of the 2 year from PreDev (Onsite) 50 year: PreDev 50 year 31 The pond’s inflow will be modeled using the Dev 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 46,274 cubic feet of storage, with 8.25 feet of detention. The proposed pond provides 50,546 cubic feet of storage, which results in a 9.2% 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. A wetpond for water quality treatment requires a length-to-width ratio greater than 3:1 which is not feasible in the proposed pond’s current configuration. Therefore, water quality treatment will be provided by a PerkFilter vault after the detention facility. The water quality treatment flow rate is defined in the SWDM to be the 2-year developed flow rate following detention. Flow Frequency Analysis LogPearson III Coefficients Time Series File:dsout.tsf Mean= -1.098 StdDev= 0.212 Project Location:Sea-Tac Skew= 0.697 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period ....................................................................... Computed Peaks 0.316 100.00 0.990 Computed Peaks 0.258 50.00 0.980 Computed Peaks 0.208 25.00 0.960 Computed Peaks 0.153 10.00 0.900 Computed Peaks 0.143 8.00 0.875 Computed Peaks 0.117 5.00 0.800 Computed Peaks 0.075 2.00 0.500 Computed Peaks 0.054 1.30 0.231 Therefore, the two post-detention water quality treatment flow rate is 0.075 cfs. 32 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 therefore will not require treatment in accordance with Core Requirement #8 of the 2009 Surface Water Design Manual. 33 Figure 4.1 Pond Tributary Area (GFGTCN9C[9#VJ#XG55WKVG014&+%4+&)'..%-+0-#&'%4155+0)(+) AREA SUMMARY BASIN TOTAL BASIN IMPERVIOUS BASIN PERVIOUS DETAINED 3.50 AC 2.02 AC 1.48 AC BYPASS 0.14 AC 0.11 AC 0.03 AC TOTAL 3.64 AC 2.13 AC 1.51 AC 34 Figure 4.2 Existing Offsite Basin KCRTS Input: C:\KC_SWDM\KC_DATA\ [C] CREATE a new Time Series ST 3.65 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 0.04 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 Flow Frequency Analysis LogPearson III Coefficients Time Series File:predev.tsf Mean= -1.055 StdDev= 0.233 Project Location:Sea-Tac Skew= -0.145 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period Computed Peaks 0.290 100.00 0.990 Computed Peaks 0.255 50.00 0.980 Computed Peaks 0.220 25.00 0.960 Computed Peaks 0.174 10.00 0.900 Computed Peaks 0.164 8.00 0.875 Computed Peaks 0.139 5.00 0.800 Computed Peaks 0.089 2.00 0.500 Computed Peaks 0.059 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:dev.tsf Mean= -0.216 StdDev= 0.112 Project Location:Sea-Tac Skew= 0.417 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period Computed Peaks 1.20 100.00 0.990 Computed Peaks 1.09 50.00 0.980 Computed Peaks 0.989 25.00 0.960 Computed Peaks 0.854 10.00 0.900 Computed Peaks 0.827 8.00 0.875 Computed Peaks 0.750 5.00 0.800 Computed Peaks 0.597 2.00 0.500 Computed Peaks 0.497 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:bypass.tsf Mean= -1.514 StdDev= 0.104 Project Location:Sea-Tac Skew= 0.489 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period Computed Peaks 0.058 100.00 0.990 Computed Peaks 0.053 50.00 0.980 Computed Peaks 0.048 25.00 0.960 Computed Peaks 0.042 10.00 0.900 Computed Peaks 0.041 8.00 0.875 Computed Peaks 0.037 5.00 0.800 Computed Peaks 0.030 2.00 0.500 Computed Peaks 0.025 1.30 0.231 Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 0.00 H:1V Pond Bottom Length: 79.00 ft Pond Bottom Width: 71.00 ft Pond Bottom Area: 5609. sq. ft Top Area at 1 ft. FB: 5609. sq. ft 0.129 acres Effective Storage Depth: 8.25 ft Stage 0 Elevation: 0.00 ft Storage Volume: 46274. cu. ft 1.062 ac-ft Riser Head: 8.25 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 0.81 0.051 2 5.38 1.44 0.095 4.0 3 6.50 1.38 0.068 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 5609. 0.01 0.01 56. 0.001 0.002 0.00 5609. 0.02 0.02 112. 0.003 0.002 0.00 5609. 0.03 0.03 168. 0.004 0.003 0.00 5609. 0.04 0.04 224. 0.005 0.004 0.00 5609. 0.05 0.05 281. 0.006 0.004 0.00 5609. 0.06 0.06 337. 0.008 0.004 0.00 5609. 0.07 0.07 393. 0.009 0.005 0.00 5609. 0.23 0.23 1290. 0.030 0.009 0.00 5609. 0.39 0.39 2188. 0.050 0.011 0.00 5609. 0.55 0.55 3085. 0.071 0.013 0.00 5609. 0.71 0.71 3982. 0.091 0.015 0.00 5609. 0.88 0.88 4936. 0.113 0.017 0.00 5609. 1.04 1.04 5833. 0.134 0.018 0.00 5609. 1.20 1.20 6731. 0.155 0.020 0.00 5609. 1.36 1.36 7628. 0.175 0.021 0.00 5609. 1.52 1.52 8526. 0.196 0.022 0.00 5609. 1.69 1.69 9479. 0.218 0.023 0.00 5609. 1.85 1.85 10377. 0.238 0.024 0.00 5609. 2.01 2.01 11274. 0.259 0.025 0.00 5609. 2.17 2.17 12172. 0.279 0.026 0.00 5609. 2.33 2.33 13069. 0.300 0.027 0.00 5609. 2.49 2.49 13966. 0.321 0.028 0.00 5609. 2.66 2.66 14920. 0.343 0.029 0.00 5609. 2.82 2.82 15817. 0.363 0.030 0.00 5609. 2.98 2.98 16715. 0.384 0.031 0.00 5609. 3.14 3.14 17612. 0.404 0.032 0.00 5609. 3.30 3.30 18510. 0.425 0.033 0.00 5609. 3.46 3.46 19407. 0.446 0.033 0.00 5609. 3.63 3.63 20361. 0.467 0.034 0.00 5609. 3.79 3.79 21258. 0.488 0.035 0.00 5609. 3.95 3.95 22156. 0.509 0.036 0.00 5609. 4.11 4.11 23053. 0.529 0.036 0.00 5609. 4.27 4.27 23950. 0.550 0.037 0.00 5609. 4.44 4.44 24904. 0.572 0.038 0.00 5609. 4.60 4.60 25801. 0.592 0.038 0.00 5609. 4.76 4.76 26699. 0.613 0.039 0.00 5609. 4.92 4.92 27596. 0.634 0.040 0.00 5609. 5.08 5.08 28494. 0.654 0.040 0.00 5609. 5.24 5.24 29391. 0.675 0.041 0.00 5609. 5.38 5.38 30176. 0.693 0.042 0.00 5609. 5.39 5.39 30233. 0.694 0.042 0.00 5609. 5.40 5.40 30289. 0.695 0.043 0.00 5609. 5.42 5.42 30401. 0.698 0.046 0.00 5609. 5.43 5.43 30457. 0.699 0.049 0.00 5609. 5.45 5.45 30569. 0.702 0.053 0.00 5609. 5.46 5.46 30625. 0.703 0.057 0.00 5609. 5.48 5.48 30737. 0.706 0.060 0.00 5609. 5.49 5.49 30793. 0.707 0.061 0.00 5609. 5.66 5.66 31747. 0.729 0.072 0.00 5609. 5.82 5.82 32644. 0.749 0.081 0.00 5609. 5.98 5.98 33542. 0.770 0.087 0.00 5609. 6.14 6.14 34439. 0.791 0.094 0.00 5609. 6.30 6.30 35337. 0.811 0.099 0.00 5609. 6.47 6.47 36290. 0.833 0.104 0.00 5609. 6.50 6.50 36459. 0.837 0.105 0.00 5609. 6.51 6.51 36515. 0.838 0.106 0.00 5609. 6.53 6.53 36627. 0.841 0.108 0.00 5609. 6.54 6.54 36683. 0.842 0.110 0.00 5609. 6.56 6.56 36795. 0.845 0.113 0.00 5609. 6.57 6.57 36851. 0.846 0.117 0.00 5609. 6.59 6.59 36963. 0.849 0.122 0.00 5609. 6.60 6.60 37019. 0.850 0.124 0.00 5609. 6.61 6.61 37075. 0.851 0.126 0.00 5609. 6.63 6.63 37188. 0.854 0.127 0.00 5609. 6.79 6.79 38085. 0.874 0.141 0.00 5609. 6.95 6.95 38983. 0.895 0.152 0.00 5609. 7.11 7.11 39880. 0.916 0.162 0.00 5609. 7.28 7.28 40834. 0.937 0.171 0.00 5609. 7.44 7.44 41731. 0.958 0.179 0.00 5609. 7.60 7.60 42628. 0.979 0.187 0.00 5609. 7.76 7.76 43526. 0.999 0.194 0.00 5609. 7.92 7.92 44423. 1.020 0.201 0.00 5609. 8.08 8.08 45321. 1.040 0.208 0.00 5609. 8.25 8.25 46274. 1.062 0.214 0.00 5609. 8.35 8.35 46835. 1.075 0.526 0.00 5609. 8.45 8.45 47396. 1.088 1.090 0.00 5609. 8.55 8.55 47957. 1.101 1.830 0.00 5609. 8.65 8.65 48518. 1.114 2.620 0.00 5609. 8.75 8.75 49079. 1.127 2.910 0.00 5609. 8.85 8.85 49640. 1.140 3.170 0.00 5609. 8.95 8.95 50201. 1.152 3.400 0.00 5609. 9.05 9.05 50761. 1.165 3.630 0.00 5609. 9.15 9.15 51322. 1.178 3.830 0.00 5609. 9.25 9.25 51883. 1.191 4.030 0.00 5609. 9.35 9.35 52444. 1.204 4.220 0.00 5609. 9.45 9.45 53005. 1.217 4.400 0.00 5609. 9.55 9.55 53566. 1.230 4.570 0.00 5609. 9.65 9.65 54127. 1.243 4.740 0.00 5609. 9.75 9.75 54688. 1.255 4.900 0.00 5609. 9.85 9.85 55249. 1.268 5.050 0.00 5609. 9.95 9.95 55810. 1.281 5.200 0.00 5609. 10.05 10.05 56370. 1.294 5.350 0.00 5609. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.65 0.20 7.84 7.84 43968. 1.009 2 0.72 0.19 7.67 7.67 43013. 0.987 3 1.02 0.17 7.36 7.36 41267. 0.947 4 0.67 0.17 7.17 7.17 40229. 0.924 5 0.68 0.17 7.19 7.19 40305. 0.925 6 0.48 0.10 6.50 6.50 36434. 0.836 7 0.36 0.04 5.38 5.38 30175. 0.693 8 0.72 0.03 3.07 3.07 17208. 0.395 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.20 0.03 ******** ******* 0.21 2 0.19 0.03 ******** ******* 0.20 3 0.17 0.05 ******** ******* 0.19 4 0.17 0.03 ******** ******* 0.17 5 0.17 0.03 ******** ******* 0.17 6 0.10 0.02 ******** ******* 0.11 7 0.04 0.02 ******** ******* 0.05 8 0.03 0.04 ******** ******* 0.06 ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:RDout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 1.12 CFS at 6:00 on Jan 9 in 1990 Peak Outflow Discharge: 0.214 CFS at 20:00 on Feb 9 in 1951 Peak Reservoir Stage: 8.25 Ft Peak Reservoir Elev: 8.25 Ft Peak Reservoir Storage: 46246. Cu-Ft : 1.062 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.227 CFS at 18:00 on Feb 9 in 1951 Point of Compliance File:dsout.tsf Flow Frequency Analysis LogPearson III Coefficients Time Series File:rdout.tsf Mean= -1.195 StdDev= 0.273 Project Location:Sea-Tac Skew= 0.470 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.038 38 2/22/49 22:00 0.214 8.25 1 89.50 0.989 0.086 17 3/05/50 7:00 0.200 7.89 2 32.13 0.969 0.214 1 2/09/51 20:00 0.176 7.37 3 19.58 0.949 0.034 43 2/04/52 8:00 0.176 7.37 4 14.08 0.929 0.082 19 1/18/53 21:00 0.174 7.34 5 10.99 0.909 0.040 33 1/07/54 21:00 0.167 7.21 6 9.01 0.889 0.037 39 11/19/54 20:00 0.166 7.19 7 7.64 0.869 0.129 10 1/06/56 10:00 0.159 7.06 8 6.63 0.849 0.039 35 3/10/57 4:00 0.142 6.80 9 5.86 0.829 0.063 25 1/17/58 8:00 0.129 6.65 10 5.24 0.809 0.039 36 1/27/59 1:00 0.117 6.57 11 4.75 0.789 0.159 8 11/21/59 3:00 0.102 6.41 12 4.34 0.769 0.098 14 11/24/60 11:00 0.098 6.27 13 3.99 0.749 0.033 44 12/24/61 6:00 0.098 6.26 14 3.70 0.729 0.068 24 11/30/62 18:00 0.097 6.25 15 3.44 0.709 0.089 16 11/19/63 17:00 0.089 6.02 16 3.22 0.690 0.097 15 12/01/64 8:00 0.086 5.97 17 3.03 0.670 0.042 28 1/07/66 4:00 0.082 5.84 18 2.85 0.650 0.079 20 12/13/66 15:00 0.082 5.84 19 2.70 0.630 0.040 32 1/20/68 22:00 0.079 5.79 20 2.56 0.610 0.041 30 12/11/68 10:00 0.078 5.76 21 2.44 0.590 0.078 21 1/27/70 3:00 0.075 5.71 22 2.32 0.570 0.041 31 12/07/70 14:00 0.070 5.63 23 2.22 0.550 0.174 5 3/06/72 22:00 0.068 5.59 24 2.13 0.530 0.102 12 12/26/72 6:00 0.063 5.53 25 2.04 0.510 0.042 27 1/18/74 20:00 0.043 5.40 26 1.96 0.490 0.038 37 1/14/75 2:00 0.042 5.39 27 1.89 0.470 0.040 34 12/04/75 10:00 0.042 5.35 28 1.82 0.450 0.029 49 8/26/77 8:00 0.041 5.29 29 1.75 0.430 0.082 18 12/15/77 19:00 0.041 5.20 30 1.70 0.410 0.030 48 2/13/79 1:00 0.041 5.19 31 1.64 0.390 0.167 6 12/17/79 20:00 0.040 5.05 32 1.59 0.370 0.041 29 12/30/80 23:00 0.040 4.96 33 1.54 0.350 0.117 11 10/06/81 19:00 0.040 4.89 34 1.49 0.330 0.043 26 1/08/83 6:00 0.039 4.80 35 1.45 0.310 0.033 45 12/13/83 8:00 0.039 4.68 36 1.41 0.291 0.034 42 11/11/84 9:00 0.038 4.45 37 1.37 0.271 0.070 23 1/19/86 6:00 0.038 4.37 38 1.33 0.251 0.142 9 11/24/86 8:00 0.037 4.34 39 1.30 0.231 0.036 40 12/10/87 8:00 0.036 4.17 40 1.27 0.211 0.033 46 11/05/88 23:00 0.036 3.93 41 1.24 0.191 0.176 3 1/09/90 14:00 0.034 3.60 42 1.21 0.171 0.176 4 11/24/90 16:00 0.034 3.58 43 1.18 0.151 0.075 22 1/31/92 6:00 0.033 3.50 44 1.15 0.131 0.032 47 1/26/93 5:00 0.033 3.50 45 1.12 0.111 0.028 50 2/17/94 23:00 0.033 3.43 46 1.10 0.091 0.098 13 12/27/94 7:00 0.032 3.16 47 1.08 0.071 0.200 2 2/09/96 4:00 0.030 2.82 48 1.05 0.051 0.166 7 1/02/97 12:00 0.029 2.67 49 1.03 0.031 0.036 41 1/25/98 0:00 0.028 2.57 50 1.01 0.011 Computed Peaks 0.340 8.29 100.00 0.990 Computed Peaks 0.270 8.27 50.00 0.980 Computed Peaks 0.211 8.15 25.00 0.960 Computed Peaks 0.146 6.87 10.00 0.900 Computed Peaks 0.135 6.72 8.00 0.875 Computed Peaks 0.106 6.51 5.00 0.800 Computed Peaks 0.061 5.49 2.00 0.500 Computed Peaks 0.039 4.79 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:dsout.tsf Mean= -1.098 StdDev= 0.212 Project Location:Sea-Tac Skew= 0.697 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.058 33 2/16/49 21:00 0.227 1 89.50 0.989 0.093 17 1/22/50 4:00 0.212 2 32.13 0.969 0.227 1 2/09/51 18:00 0.187 3 19.58 0.949 0.047 45 1/30/52 8:00 0.185 4 14.08 0.929 0.089 18 1/18/53 19:00 0.184 5 10.99 0.909 0.057 36 12/19/53 19:00 0.176 6 9.01 0.889 0.063 27 11/25/54 2:00 0.176 7 7.64 0.869 0.135 10 1/06/56 9:00 0.167 8 6.63 0.849 0.062 28 12/09/56 14:00 0.147 9 5.86 0.829 0.066 26 1/17/58 6:00 0.135 10 5.24 0.809 0.059 32 1/26/59 20:00 0.130 11 4.75 0.789 0.167 8 11/21/59 1:00 0.110 12 4.34 0.769 0.108 13 11/24/60 8:00 0.108 13 3.99 0.749 0.047 46 12/22/61 17:00 0.105 14 3.70 0.729 0.071 24 11/30/62 17:00 0.105 15 3.44 0.709 0.095 16 11/19/63 15:00 0.095 16 3.22 0.690 0.105 14 12/01/64 6:00 0.093 17 3.03 0.670 0.062 29 1/05/66 16:00 0.089 18 2.85 0.650 0.083 20 12/13/66 10:00 0.087 19 2.70 0.630 0.061 30 8/24/68 16:00 0.083 20 2.56 0.610 0.054 39 12/15/68 15:00 0.082 21 2.44 0.590 0.082 21 1/27/70 1:00 0.079 22 2.32 0.570 0.058 34 12/06/70 8:00 0.072 23 2.22 0.550 0.184 5 3/06/72 19:00 0.071 24 2.13 0.530 0.110 12 12/26/72 3:00 0.066 25 2.04 0.510 0.056 37 11/28/73 9:00 0.066 26 1.96 0.490 0.066 25 12/26/74 23:00 0.063 27 1.89 0.470 0.053 41 12/02/75 20:00 0.062 28 1.82 0.450 0.055 38 8/26/77 2:00 0.062 29 1.75 0.430 0.087 19 12/15/77 16:00 0.061 30 1.70 0.410 0.044 48 9/08/79 15:00 0.060 31 1.64 0.390 0.176 6 12/17/79 19:00 0.059 32 1.59 0.370 0.060 31 11/21/80 11:00 0.058 33 1.54 0.350 0.130 11 10/06/81 15:00 0.058 34 1.49 0.330 0.054 40 1/05/83 8:00 0.057 35 1.45 0.310 0.051 43 1/03/84 1:00 0.057 36 1.41 0.291 0.047 47 11/11/84 1:00 0.056 37 1.37 0.271 0.072 23 1/19/86 6:00 0.055 38 1.33 0.251 0.147 9 11/24/86 7:00 0.054 39 1.30 0.231 0.051 44 12/09/87 16:00 0.054 40 1.27 0.211 0.051 42 11/05/88 14:00 0.053 41 1.24 0.191 0.185 4 1/09/90 10:00 0.051 42 1.21 0.171 0.187 3 11/24/90 14:00 0.051 43 1.18 0.151 0.079 22 1/31/92 5:00 0.051 44 1.15 0.131 0.041 49 3/22/93 22:00 0.047 45 1.12 0.111 0.041 50 2/17/94 18:00 0.047 46 1.10 0.091 0.105 15 12/27/94 5:00 0.047 47 1.08 0.071 0.212 2 2/09/96 2:00 0.044 48 1.05 0.051 0.176 7 1/02/97 11:00 0.041 49 1.03 0.031 0.057 35 10/04/97 15:00 0.041 50 1.01 0.011 Computed Peaks 0.316 100.00 0.990 Computed Peaks 0.258 50.00 0.980 Computed Peaks 0.208 25.00 0.960 Computed Peaks 0.153 10.00 0.900 Computed Peaks 0.143 8.00 0.875 Computed Peaks 0.117 5.00 0.800 Computed Peaks 0.075 2.00 0.500 Computed Peaks 0.054 1.30 0.231 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 197198 45.022 45.022 54.978 0.550E+00 0.009 55938 12.771 57.794 42.206 0.422E+00 0.015 59194 13.515 71.308 28.692 0.287E+00 0.021 44212 10.094 81.402 18.598 0.186E+00 0.027 37736 8.616 90.018 9.982 0.998E-01 0.033 24167 5.518 95.535 4.465 0.446E-01 0.039 12950 2.957 98.492 1.508 0.151E-01 0.045 4339 0.991 99.483 0.517 0.517E-02 0.051 164 0.037 99.520 0.480 0.480E-02 0.057 89 0.020 99.540 0.460 0.460E-02 0.063 216 0.049 99.590 0.410 0.410E-02 0.069 316 0.072 99.662 0.338 0.338E-02 0.075 254 0.058 99.720 0.280 0.280E-02 0.081 223 0.051 99.771 0.229 0.229E-02 0.087 239 0.055 99.825 0.175 0.175E-02 0.093 145 0.033 99.858 0.142 0.142E-02 0.099 180 0.041 99.900 0.100 0.100E-02 0.105 138 0.032 99.931 0.069 0.689E-03 0.111 27 0.006 99.937 0.063 0.628E-03 0.117 17 0.004 99.941 0.059 0.589E-03 0.123 13 0.003 99.944 0.056 0.559E-03 0.129 33 0.008 99.952 0.048 0.484E-03 0.135 25 0.006 99.957 0.043 0.427E-03 0.141 21 0.005 99.962 0.038 0.379E-03 0.147 19 0.004 99.966 0.034 0.336E-03 0.153 21 0.005 99.971 0.029 0.288E-03 0.159 21 0.005 99.976 0.024 0.240E-03 0.165 23 0.005 99.981 0.019 0.187E-03 0.171 22 0.005 99.986 0.014 0.137E-03 0.177 27 0.006 99.992 0.008 0.753E-04 0.183 6 0.001 99.994 0.006 0.616E-04 0.189 5 0.001 99.995 0.005 0.502E-04 0.195 5 0.001 99.996 0.004 0.388E-04 0.201 7 0.002 99.998 0.002 0.228E-04 0.207 3 0.001 99.998 0.002 0.160E-04 0.213 5 0.001 100.000 0.000 0.457E-05 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 197756 45.150 45.150 54.850 0.549E+00 0.010 60860 13.895 59.045 40.955 0.410E+00 0.016 55157 12.593 71.638 28.362 0.284E+00 0.022 46646 10.650 82.287 17.713 0.177E+00 0.029 35724 8.156 90.444 9.556 0.956E-01 0.035 22583 5.156 95.600 4.400 0.440E-01 0.041 13458 3.073 98.672 1.328 0.133E-01 0.048 2945 0.672 99.345 0.655 0.655E-02 0.054 592 0.135 99.480 0.520 0.520E-02 0.061 247 0.056 99.536 0.464 0.464E-02 0.067 308 0.070 99.606 0.394 0.394E-02 0.073 299 0.068 99.675 0.325 0.325E-02 0.080 262 0.060 99.734 0.266 0.266E-02 0.086 244 0.056 99.790 0.210 0.210E-02 0.092 203 0.046 99.837 0.163 0.163E-02 0.099 157 0.036 99.872 0.128 0.128E-02 0.105 181 0.041 99.914 0.086 0.863E-03 0.112 69 0.016 99.929 0.071 0.705E-03 0.118 25 0.006 99.935 0.065 0.648E-03 0.124 28 0.006 99.942 0.058 0.584E-03 0.131 25 0.006 99.947 0.053 0.527E-03 0.137 33 0.008 99.955 0.045 0.452E-03 0.143 21 0.005 99.960 0.040 0.404E-03 0.150 24 0.005 99.965 0.035 0.349E-03 0.156 17 0.004 99.969 0.031 0.311E-03 0.162 20 0.005 99.974 0.026 0.265E-03 0.169 23 0.005 99.979 0.021 0.212E-03 0.175 23 0.005 99.984 0.016 0.160E-03 0.182 18 0.004 99.988 0.012 0.119E-03 0.188 24 0.005 99.994 0.006 0.639E-04 0.194 5 0.001 99.995 0.005 0.525E-04 0.201 4 0.001 99.996 0.004 0.434E-04 0.207 6 0.001 99.997 0.003 0.297E-04 0.213 5 0.001 99.998 0.002 0.183E-04 0.220 5 0.001 99.999 0.001 0.685E-05 0.226 2 0.000 100.000 0.000 0.228E-05 ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:RDout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 1.12 CFS at 6:00 on Jan 9 in 1990 Peak Outflow Discharge: 0.214 CFS at 20:00 on Feb 9 in 1951 Peak Reservoir Stage: 8.25 Ft Peak Reservoir Elev: 8.25 Ft Peak Reservoir Storage: 46246. Cu-Ft : 1.062 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.227 CFS at 18:00 on Feb 9 in 1951 Point of Compliance File:dsout.tsf Flow Frequency Analysis LogPearson III Coefficients Time Series File:rdout.tsf Mean= -1.195 StdDev= 0.273 Project Location:Sea-Tac Skew= 0.470 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.038 38 2/22/49 22:00 0.214 8.25 1 89.50 0.989 0.086 17 3/05/50 7:00 0.200 7.89 2 32.13 0.969 0.214 1 2/09/51 20:00 0.176 7.37 3 19.58 0.949 0.034 43 2/04/52 8:00 0.176 7.37 4 14.08 0.929 0.082 19 1/18/53 21:00 0.174 7.34 5 10.99 0.909 0.040 33 1/07/54 21:00 0.167 7.21 6 9.01 0.889 0.037 39 11/19/54 20:00 0.166 7.19 7 7.64 0.869 0.129 10 1/06/56 10:00 0.159 7.06 8 6.63 0.849 0.039 35 3/10/57 4:00 0.142 6.80 9 5.86 0.829 0.063 25 1/17/58 8:00 0.129 6.65 10 5.24 0.809 0.039 36 1/27/59 1:00 0.117 6.57 11 4.75 0.789 0.159 8 11/21/59 3:00 0.102 6.41 12 4.34 0.769 0.098 14 11/24/60 11:00 0.098 6.27 13 3.99 0.749 0.033 44 12/24/61 6:00 0.098 6.26 14 3.70 0.729 0.068 24 11/30/62 18:00 0.097 6.25 15 3.44 0.709 0.089 16 11/19/63 17:00 0.089 6.02 16 3.22 0.690 0.097 15 12/01/64 8:00 0.086 5.97 17 3.03 0.670 0.042 28 1/07/66 4:00 0.082 5.84 18 2.85 0.650 0.079 20 12/13/66 15:00 0.082 5.84 19 2.70 0.630 0.040 32 1/20/68 22:00 0.079 5.79 20 2.56 0.610 0.041 30 12/11/68 10:00 0.078 5.76 21 2.44 0.590 0.078 21 1/27/70 3:00 0.075 5.71 22 2.32 0.570 0.041 31 12/07/70 14:00 0.070 5.63 23 2.22 0.550 0.174 5 3/06/72 22:00 0.068 5.59 24 2.13 0.530 0.102 12 12/26/72 6:00 0.063 5.53 25 2.04 0.510 0.042 27 1/18/74 20:00 0.043 5.40 26 1.96 0.490 0.038 37 1/14/75 2:00 0.042 5.39 27 1.89 0.470 0.040 34 12/04/75 10:00 0.042 5.35 28 1.82 0.450 0.029 49 8/26/77 8:00 0.041 5.29 29 1.75 0.430 0.082 18 12/15/77 19:00 0.041 5.20 30 1.70 0.410 0.030 48 2/13/79 1:00 0.041 5.19 31 1.64 0.390 0.167 6 12/17/79 20:00 0.040 5.05 32 1.59 0.370 0.041 29 12/30/80 23:00 0.040 4.96 33 1.54 0.350 0.117 11 10/06/81 19:00 0.040 4.89 34 1.49 0.330 0.043 26 1/08/83 6:00 0.039 4.80 35 1.45 0.310 0.033 45 12/13/83 8:00 0.039 4.68 36 1.41 0.291 0.034 42 11/11/84 9:00 0.038 4.45 37 1.37 0.271 0.070 23 1/19/86 6:00 0.038 4.37 38 1.33 0.251 0.142 9 11/24/86 8:00 0.037 4.34 39 1.30 0.231 0.036 40 12/10/87 8:00 0.036 4.17 40 1.27 0.211 0.033 46 11/05/88 23:00 0.036 3.93 41 1.24 0.191 0.176 3 1/09/90 14:00 0.034 3.60 42 1.21 0.171 0.176 4 11/24/90 16:00 0.034 3.58 43 1.18 0.151 0.075 22 1/31/92 6:00 0.033 3.50 44 1.15 0.131 0.032 47 1/26/93 5:00 0.033 3.50 45 1.12 0.111 0.028 50 2/17/94 23:00 0.033 3.43 46 1.10 0.091 0.098 13 12/27/94 7:00 0.032 3.16 47 1.08 0.071 0.200 2 2/09/96 4:00 0.030 2.82 48 1.05 0.051 0.166 7 1/02/97 12:00 0.029 2.67 49 1.03 0.031 0.036 41 1/25/98 0:00 0.028 2.57 50 1.01 0.011 Computed Peaks 0.340 8.29 100.00 0.990 Computed Peaks 0.270 8.27 50.00 0.980 Computed Peaks 0.211 8.15 25.00 0.960 Computed Peaks 0.146 6.87 10.00 0.900 Computed Peaks 0.135 6.72 8.00 0.875 Computed Peaks 0.106 6.51 5.00 0.800 Computed Peaks 0.061 5.49 2.00 0.500 Computed Peaks 0.039 4.79 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:dsout.tsf Mean= -1.098 StdDev= 0.212 Project Location:Sea-Tac Skew= 0.697 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.058 33 2/16/49 21:00 0.227 1 89.50 0.989 0.093 17 1/22/50 4:00 0.212 2 32.13 0.969 0.227 1 2/09/51 18:00 0.187 3 19.58 0.949 0.047 45 1/30/52 8:00 0.185 4 14.08 0.929 0.089 18 1/18/53 19:00 0.184 5 10.99 0.909 0.057 36 12/19/53 19:00 0.176 6 9.01 0.889 0.063 27 11/25/54 2:00 0.176 7 7.64 0.869 0.135 10 1/06/56 9:00 0.167 8 6.63 0.849 0.062 28 12/09/56 14:00 0.147 9 5.86 0.829 0.066 26 1/17/58 6:00 0.135 10 5.24 0.809 0.059 32 1/26/59 20:00 0.130 11 4.75 0.789 0.167 8 11/21/59 1:00 0.110 12 4.34 0.769 0.108 13 11/24/60 8:00 0.108 13 3.99 0.749 0.047 46 12/22/61 17:00 0.105 14 3.70 0.729 0.071 24 11/30/62 17:00 0.105 15 3.44 0.709 0.095 16 11/19/63 15:00 0.095 16 3.22 0.690 0.105 14 12/01/64 6:00 0.093 17 3.03 0.670 0.062 29 1/05/66 16:00 0.089 18 2.85 0.650 0.083 20 12/13/66 10:00 0.087 19 2.70 0.630 0.061 30 8/24/68 16:00 0.083 20 2.56 0.610 0.054 39 12/15/68 15:00 0.082 21 2.44 0.590 0.082 21 1/27/70 1:00 0.079 22 2.32 0.570 0.058 34 12/06/70 8:00 0.072 23 2.22 0.550 0.184 5 3/06/72 19:00 0.071 24 2.13 0.530 0.110 12 12/26/72 3:00 0.066 25 2.04 0.510 0.056 37 11/28/73 9:00 0.066 26 1.96 0.490 0.066 25 12/26/74 23:00 0.063 27 1.89 0.470 0.053 41 12/02/75 20:00 0.062 28 1.82 0.450 0.055 38 8/26/77 2:00 0.062 29 1.75 0.430 0.087 19 12/15/77 16:00 0.061 30 1.70 0.410 0.044 48 9/08/79 15:00 0.060 31 1.64 0.390 0.176 6 12/17/79 19:00 0.059 32 1.59 0.370 0.060 31 11/21/80 11:00 0.058 33 1.54 0.350 0.130 11 10/06/81 15:00 0.058 34 1.49 0.330 0.054 40 1/05/83 8:00 0.057 35 1.45 0.310 0.051 43 1/03/84 1:00 0.057 36 1.41 0.291 0.047 47 11/11/84 1:00 0.056 37 1.37 0.271 0.072 23 1/19/86 6:00 0.055 38 1.33 0.251 0.147 9 11/24/86 7:00 0.054 39 1.30 0.231 0.051 44 12/09/87 16:00 0.054 40 1.27 0.211 0.051 42 11/05/88 14:00 0.053 41 1.24 0.191 0.185 4 1/09/90 10:00 0.051 42 1.21 0.171 0.187 3 11/24/90 14:00 0.051 43 1.18 0.151 0.079 22 1/31/92 5:00 0.051 44 1.15 0.131 0.041 49 3/22/93 22:00 0.047 45 1.12 0.111 0.041 50 2/17/94 18:00 0.047 46 1.10 0.091 0.105 15 12/27/94 5:00 0.047 47 1.08 0.071 0.212 2 2/09/96 2:00 0.044 48 1.05 0.051 0.176 7 1/02/97 11:00 0.041 49 1.03 0.031 0.057 35 10/04/97 15:00 0.041 50 1.01 0.011 Computed Peaks 0.316 100.00 0.990 Computed Peaks 0.258 50.00 0.980 Computed Peaks 0.208 25.00 0.960 Computed Peaks 0.153 10.00 0.900 Computed Peaks 0.143 8.00 0.875 Computed Peaks 0.117 5.00 0.800 Computed Peaks 0.075 2.00 0.500 Computed Peaks 0.054 1.30 0.231 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 197198 45.022 45.022 54.978 0.550E+00 0.009 55938 12.771 57.794 42.206 0.422E+00 0.015 59194 13.515 71.308 28.692 0.287E+00 0.021 44212 10.094 81.402 18.598 0.186E+00 0.027 37736 8.616 90.018 9.982 0.998E-01 0.033 24167 5.518 95.535 4.465 0.446E-01 0.039 12950 2.957 98.492 1.508 0.151E-01 0.045 4339 0.991 99.483 0.517 0.517E-02 0.051 164 0.037 99.520 0.480 0.480E-02 0.057 89 0.020 99.540 0.460 0.460E-02 0.063 216 0.049 99.590 0.410 0.410E-02 0.069 316 0.072 99.662 0.338 0.338E-02 0.075 254 0.058 99.720 0.280 0.280E-02 0.081 223 0.051 99.771 0.229 0.229E-02 0.087 239 0.055 99.825 0.175 0.175E-02 0.093 145 0.033 99.858 0.142 0.142E-02 0.099 180 0.041 99.900 0.100 0.100E-02 0.105 138 0.032 99.931 0.069 0.689E-03 0.111 27 0.006 99.937 0.063 0.628E-03 0.117 17 0.004 99.941 0.059 0.589E-03 0.123 13 0.003 99.944 0.056 0.559E-03 0.129 33 0.008 99.952 0.048 0.484E-03 0.135 25 0.006 99.957 0.043 0.427E-03 0.141 21 0.005 99.962 0.038 0.379E-03 0.147 19 0.004 99.966 0.034 0.336E-03 0.153 21 0.005 99.971 0.029 0.288E-03 0.159 21 0.005 99.976 0.024 0.240E-03 0.165 23 0.005 99.981 0.019 0.187E-03 0.171 22 0.005 99.986 0.014 0.137E-03 0.177 27 0.006 99.992 0.008 0.753E-04 0.183 6 0.001 99.994 0.006 0.616E-04 0.189 5 0.001 99.995 0.005 0.502E-04 0.195 5 0.001 99.996 0.004 0.388E-04 0.201 7 0.002 99.998 0.002 0.228E-04 0.207 3 0.001 99.998 0.002 0.160E-04 0.213 5 0.001 100.000 0.000 0.457E-05 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.003 197756 45.150 45.150 54.850 0.549E+00 0.010 60860 13.895 59.045 40.955 0.410E+00 0.016 55157 12.593 71.638 28.362 0.284E+00 0.022 46646 10.650 82.287 17.713 0.177E+00 0.029 35724 8.156 90.444 9.556 0.956E-01 0.035 22583 5.156 95.600 4.400 0.440E-01 0.041 13458 3.073 98.672 1.328 0.133E-01 0.048 2945 0.672 99.345 0.655 0.655E-02 0.054 592 0.135 99.480 0.520 0.520E-02 0.061 247 0.056 99.536 0.464 0.464E-02 0.067 308 0.070 99.606 0.394 0.394E-02 0.073 299 0.068 99.675 0.325 0.325E-02 0.080 262 0.060 99.734 0.266 0.266E-02 0.086 244 0.056 99.790 0.210 0.210E-02 0.092 203 0.046 99.837 0.163 0.163E-02 0.099 157 0.036 99.872 0.128 0.128E-02 0.105 181 0.041 99.914 0.086 0.863E-03 0.112 69 0.016 99.929 0.071 0.705E-03 0.118 25 0.006 99.935 0.065 0.648E-03 0.124 28 0.006 99.942 0.058 0.584E-03 0.131 25 0.006 99.947 0.053 0.527E-03 0.137 33 0.008 99.955 0.045 0.452E-03 0.143 21 0.005 99.960 0.040 0.404E-03 0.150 24 0.005 99.965 0.035 0.349E-03 0.156 17 0.004 99.969 0.031 0.311E-03 0.162 20 0.005 99.974 0.026 0.265E-03 0.169 23 0.005 99.979 0.021 0.212E-03 0.175 23 0.005 99.984 0.016 0.160E-03 0.182 18 0.004 99.988 0.012 0.119E-03 0.188 24 0.005 99.994 0.006 0.639E-04 0.194 5 0.001 99.995 0.005 0.525E-04 0.201 4 0.001 99.996 0.004 0.434E-04 0.207 6 0.001 99.997 0.003 0.297E-04 0.213 5 0.001 99.998 0.002 0.183E-04 0.220 5 0.001 99.999 0.001 0.685E-05 0.226 2 0.000 100.000 0.000 0.228E-05 Duration Comparison Anaylsis Base File: predev.tsf New File: dsout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New %Change Probability Base New %Change 0.044 | 0.10E-01 0.87E-02 -14.5 | 0.10E-01 0.044 0.043 -2.7 0.060 | 0.52E-02 0.47E-02 -10.0 | 0.52E-02 0.060 0.054 -9.5 0.075 | 0.29E-02 0.31E-02 5.8 | 0.29E-02 0.075 0.077 2.1 0.090 | 0.18E-02 0.18E-02 0.4 | 0.18E-02 0.090 0.091 0.1 0.106 | 0.11E-02 0.83E-03 -23.3 | 0.11E-02 0.106 0.102 -4.1 0.121 | 0.67E-03 0.61E-03 -9.2 | 0.67E-03 0.121 0.115 -5.0 0.137 | 0.44E-03 0.45E-03 2.1 | 0.44E-03 0.137 0.138 1.1 0.152 | 0.30E-03 0.34E-03 11.3 | 0.30E-03 0.152 0.157 2.9 0.168 | 0.21E-03 0.22E-03 5.4 | 0.21E-03 0.168 0.169 0.6 0.183 | 0.12E-03 0.94E-04 -19.6 | 0.12E-03 0.183 0.182 -0.8 0.199 | 0.59E-04 0.48E-04 -19.2 | 0.59E-04 0.199 0.191 -4.1 0.214 | 0.32E-04 0.14E-04 -57.1 | 0.32E-04 0.214 0.207 -3.6 0.230 | 0.68E-05 0.00E+00 -100.0 | 0.68E-05 0.230 0.221 -4.0 0.245 | 0.23E-05 0.00E+00 -100.0 | 0.23E-05 0.245 0.227 -7.5 Maximum positive excursion = 0.005 cfs ( 3.0%) occurring at 0.151 cfs on the Base Data:predev.tsf and at 0.156 cfs on the New Data:dsout.tsf Maximum negative excursion = 0.006 cfs (-11.7%) occurring at 0.055 cfs on the Base Data:predev.tsf and at 0.048 cfs on the New Data:dsout.tsf 35 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The onsite stormwater drainage conveyance system has been sized to convey and contain the onsite 100 year design storm event as computed via the Rational Method. The offsite area that is collected by the drainage ditch along 116th Ave SE will bypass the onsite conveyance system in a pipe within the ROW. Due to the conservative nature of the Rational Method, the offsite area’s conveyance flow rate has been calculated with the KCRTS 15 minute time series to better represent the existing conditions. The onsite developed outflow from the detention facility has been calculated via KCRTS. The calculated flow rates through the offsite conveyance system, downstream of onsite detention, are over the flow rate capacity of the proposed system. However, the resultant flow from the developed onsite area combined with the existing offsite area is contained within the catch basins and pipes in this section of the proposed conveyance system, as determined in the Backwater Analysis. Per Section 4.2.1.2 (Conveyance Capacity) in the SWDM, the results of the Backwater Analysis method determine final pipe sizes in all cases. Therefore the conveyance system has sufficient capacity. The calculations are included following this page. CONVEYANCE CALCULATIONPipePervious Area(acres)Impervious Area(acres)Total Area(acres)25-yearTotal Flow(cfs) 100-yearTotal Flow(cfs) Pipe Diameter (in)Pipe Diameter (ft)Area (ft2)Wet Perimeter (ft)Hydraulic Radius (ft)Slope (ft/ft)Pipe nCapacity (cfs)Velocity @25-year Capacity (ft/sec)25 year % Capacity (cfs)100 year % Capacity (cfs)CB #23 to CB #220.000.000.002.403.751210.7853.1420.2500.1250.01312.6216.0719%30%CB #21 to CB #200.000.000.000.210.341210.7853.1420.2500.0140.0134.175.315%8%CB #20 to CB #190.000.000.000.210.341210.7853.1420.2500.0130.0134.135.255%8%CB #19 to Filter Vault**0.000.000.000.210.341210.7853.1420.2500.0140.0134.165.295%8%Filter Vault to CB #18**0.000.000.000.210.341210.7853.1420.2500.0050.0132.563.268%13%CB #18 to CB #17**0.000.000.002.614.091210.7853.1420.2500.0050.0132.533.22103%162%CB #22 to CB #18*1.761.743.502.403.751210.7853.1420.2500.0350.0136.708.5336%56%CB #23 to CB #22*0.000.000.002.403.751210.7853.1420.2500.1250.01312.6216.0719%30%CB #16 to CB #150.000.040.040.110.131210.7853.1420.2500.0100.0133.504.463%4%CB #15 to CB #140.020.080.100.320.371210.7853.1420.2500.0060.0132.783.5412%13%CB #14 to CB #130.100.180.280.820.951210.7853.1420.2500.0220.0135.316.7515%18%CB #13 to CB #120.000.000.000.820.951210.7853.1420.2500.0880.01310.5713.468%9%CB #12 to Pond0.000.000.000.820.951210.7853.1420.2500.0060.0132.683.4131%36%CB #9 to CB #80.250.370.611.001.171210.7853.1420.2500.0110.0133.714.7227%31%CB #8 to CB #70.090.040.121.091.281210.7853.1420.2500.0500.0137.9610.1314%16%CB #7 to CB #60.010.020.021.151.341210.7853.1420.2500.0260.0135.767.3320%23%CB #11 to CB #100.130.290.410.780.911210.7853.1420.2500.0050.0132.533.2231%36%CB #10 to CB #60.020.050.070.921.081210.7853.1420.2500.0050.0132.573.2736%42%CB #6 to CB #10.060.120.182.402.801210.7853.1420.2500.1300.01312.8816.4019%22%CB #5 to CB #40.180.400.581.081.271210.7853.1420.2500.0050.0132.573.2742%49%CB #4 to CB #20.000.000.001.081.271210.7853.1420.2500.0050.0132.483.1644%51%CB #3 to CB #20.150.310.460.850.991210.7853.1420.2500.0200.0135.056.4317%20%CB #2 to CB #10.060.110.172.242.611210.7853.1420.2500.0060.0132.773.5281%94%*The pipes that will convey the existing upstream offsite flows to the existing downstream piped conveyance system.**These pipes are downstream of detention and Backwater Analysis confirms that the 100-year storm event is contained in the catch basins BACKWATER CALCULATION1234567891011121314151617181920Pipe100-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 Pond2.781120.011450.8456.90.793.440.18459.10.33459.40.090.18459.7458.00.170.220.00459.7466.87.1CB #2 to CB #12.670120.011456.9457.30.793.330.17459.70.27460.00.090.17460.2458.40.040.050.07460.2462.72.5CB #3 to CB #21.017120.011457.3457.70.791.260.02460.20.01460.20.010.02460.2458.40.000.000.00460.2462.72.4CB #4 to CB #21.331120.011457.3457.50.791.610.04460.20.03460.20.020.04460.3458.20.040.050.00460.3461.71.4CB #5 to CB #41.331120.011457.5457.60.791.610.04460.30.03460.30.020.04460.4458.40.000.000.00460.4461.10.8CB #6 to CB #12.870120.011456.9466.00.793.570.20460.20.31460.50.100.20460.8467.10.050.060.08467.1471.03.9CB #10 to CB #61.131120.011466.0466.20.791.370.03467.10.02467.10.010.03467.1466.90.020.030.00467.1470.93.8CB #11 to CB #100.932120.011466.2466.30.791.160.02467.10.01467.10.010.02467.2467.00.000.000.00467.1471.34.1CB #7 to CB #61.3100120.011466.0468.60.791.700.05467.10.10467.20.020.05467.2469.40.040.050.00469.4473.64.2CB #8 to CB #71.377120.011468.6472.40.791.630.04469.40.07469.50.020.04469.5473.20.030.040.00473.2475.92.7CB #9 to CB #81.226120.011472.4472.70.791.480.03473.20.02473.20.020.03473.2473.50.000.000.00473.4476.22.8CB #12 to Pond1.016120.011450.8450.90.791.220.02459.10.01459.10.010.02459.1451.60.020.030.00459.1454.2-4.9*CB #13 to CB #121.067120.011450.9456.80.791.220.02459.10.03459.20.010.02459.2457.50.020.030.00459.2461.92.7CB #14 to CB #131.073120.011456.8458.40.791.220.02459.20.04459.20.010.02459.3459.10.000.000.00459.3465.86.6CB #15 to CB #140.428120.011458.4458.60.790.480.00459.30.00459.30.000.00459.3459.20.000.000.00459.3463.64.3CB #16 to CB #150.125120.011458.6458.80.790.160.00459.30.00459.30.000.00459.3459.50.000.000.00459.5463.84.3CB #22 to CB #183.8298120.011449.2459.70.794.770.35451.52.34453.80.180.35454.3461.30.350.460.00461.4464.73.3CB #18 to CB #174.1134120.011448.6449.20.795.210.42449.61.25450.80.210.42451.4451.00.350.460.00451.5457.86.3Filter Vault to CB #18***0.335120.011449.2449.40.790.430.00451.50.00451.50.000.00451.5450.10.000.000.00451.5463.011.5CB #19 to Filter Vault***0.317120.011450.3450.50.790.430.00451.50.00451.50.000.00451.5451.20.000.000.00451.5460.59.0CB #20 to CB #19***0.312120.011450.5450.70.790.430.00451.50.00451.50.000.00451.5451.40.000.000.00451.5459.37.8CB #21 to CB #200.311120.011450.7450.80.790.430.00451.50.00451.50.000.00451.5451.50.000.000.00451.5459.17.6CB #23 to CB #223.821120.011459.7462.30.794.770.35461.40.16461.50.180.35462.1463.80.000.000.00463.5464.20.7*The rim elevation of this catch basin will be located in the detention pond and will be below the top of live storage.**The Manning's n value used in Backwater analysis differs from the Conveyance analysis n value per 2009 KCSWDM, Section 4.2, Table 4.2.1.D. ***The pipes that will convey the existing upstream offsite flows to the existing downstream piped conveyance system. 37 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: 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): 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 Retaining existing vegetation whenever feasible Establishing a quarry spall construction entrance Installing siltation control fencing or anchored straw or coir wattles on the downhill side of work areas Covering soil stockpiles with anchored plastic sheeting 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 Directing runoff away from exposed soils and slopes 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.) Decreasing runoff velocities with check dams, straw bales or coir wattles Confining sediment to the project site 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: 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 Exposed soil along the slope is protected from surface erosion using waterproof tarps and/or plastic sheeting Construction activities are scheduled so that the length of time the temporary cut is left open is minimized Surface water is diverted away from the excavation 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: 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 38 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 39 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 detention 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 3.64 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 40 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT The Site Improvement Bond Quantity Worksheet is attached following this page. Site Improvement Bond Quantity Worksheet S15 Web date: 04/03/2015 Department of Permitting & Environmental Review 35030 SE Douglas Street, Suite 210 Snoqualmie, Washington 98065-9266 206-296-6600 TTY Relay 711 Project 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 9 Kinkade Crossing 17709 116th Avenue SE, Renton WA For alternate formats, call 206-296-6600. __________________ 8/16/2016 U16-001701 li-wks-sbqxls.xls Unit prices updated: 3/2/2015 Version: 3/2/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet S15 Web date: 04/03/2015 Unit # of Reference #Price Unit Quantity Applications Cost EROSION/SEDIMENT CONTROL Number Backfill & compaction-embankment ESC-1 6.00$CY 5510 1 33060 Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 80.00$Each Crushed surfacing 1 1/4" minus ESC-3 WSDOT 9-03.9(3)95.00$CY Ditching ESC-4 9.00$CY 676 1 6084 Excavation-bulk ESC-5 2.00$CY 5130 1 10260 Fence, silt ESC-6 SWDM 5.4.3.1 1.50$LF 1536 1 2304 Fence, Temporary (NGPE)ESC-7 1.50$LF Hydroseeding ESC-8 SWDM 5.4.2.4 0.80$SY 12695 1 10156 Jute Mesh ESC-9 SWDM 5.4.2.2 3.50$SY Mulch, by hand, straw, 3" deep ESC-10 SWDM 5.4.2.1 2.50$SY Mulch, by machine, straw, 2" deep ESC-11 SWDM 5.4.2.1 2.00$SY Piping, temporary, CPP, 6"ESC-12 12.00$LF Piping, temporary, CPP, 8"ESC-13 14.00$LF Piping, temporary, CPP, 12"ESC-14 18.00$LF Plastic covering, 6mm thick, sandbagged ESC-15 SWDM 5.4.2.3 4.00$SY Rip Rap, machine placed; slopes ESC-16 WSDOT 9-13.1(2)45.00$CY Rock Construction Entrance, 50'x15'x1'ESC-17 SWDM 5.4.4.1 1,800.00$Each Rock Construction Entrance, 100'x15'x1'ESC-18 SWDM 5.4.4.1 3,200.00$Each 2 1 6400 Sediment pond riser assembly ESC-19 SWDM 5.4.5.2 2,200.00$Each 1 1 2200 Sediment trap, 5' high berm ESC-20 SWDM 5.4.5.1 19.00$LF Sed. trap, 5' high, riprapped spillway berm section ESC-21 SWDM 5.4.5.1 70.00$LF Seeding, by hand ESC-22 SWDM 5.4.2.4 1.00$SY Sodding, 1" deep, level ground ESC-23 SWDM 5.4.2.5 8.00$SY Sodding, 1" deep, sloped ground ESC-24 SWDM 5.4.2.5 10.00$SY TESC Supervisor ESC-25 110.00$HR Water truck, dust control ESC-26 SWDM 5.4.7 140.00$HR WRITE-IN-ITEMS **** (see page 9) Each ESC SUBTOTAL:70,464.00$ 30% CONTINGENCY & MOBILIZATION:21,139.20$ ESC TOTAL:91,603.20$ COLUMN:A Page 2 of 9 li-wks-sbqxls.xls Unit prices updated: 3/2/2015 Version: 3/2/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Private Right-of-Way Right of Way Improvements Unit Price Unit Quant.Cost Quant.Cost Quant.Cost GENERAL ITEMS No. Backfill & Compaction- embankment GI - 1 6.00$CY 5510 33,060.00 Backfill & Compaction- trench GI - 2 9.00$CY Clear/Remove Brush, by hand GI - 3 1.00$SY Clearing/Grubbing/Tree Removal GI - 4 10,000.00$Acre 3.6 36,000.00 Excavation - bulk GI - 5 2.00$CY 5130 10,260.00 Excavation - Trench GI - 6 5.00$CY Fencing, cedar, 6' high GI - 7 20.00$LF Fencing, chain link, vinyl coated, 6' high GI - 8 20.00$LF 503 10,060.00 Fencing, chain link, gate, vinyl coated, 20'GI - 9 1,400.00$Each 1 1,400.00 Fencing, split rail, 3' high GI - 10 15.00$LF Fill & compact - common barrow GI - 11 25.00$CY Fill & compact - gravel base GI - 12 27.00$CY Fill & compact - screened topsoil GI - 13 39.00$CY Gabion, 12" deep, stone filled mesh GI - 14 65.00$SY Gabion, 18" deep, stone filled mesh GI - 15 90.00$SY Gabion, 36" deep, stone filled mesh GI - 16 150.00$SY Grading, fine, by hand GI - 17 2.50$SY Grading, fine, with grader GI - 18 2.00$SY 387 774.00 4686 9,372.00 Monuments, 3' long GI - 19 250.00$Each 1 250.00 3 750.00 Sensitive Areas Sign GI - 20 7.00$Each Sodding, 1" deep, sloped ground GI - 21 8.00$SY Surveying, line & grade GI - 22 850.00$Day Surveying, lot location/lines GI - 23 1,800.00$Acre Traffic control crew ( 2 flaggers )GI - 24 120.00$HR Trail, 4" chipped wood GI - 25 8.00$SY Trail, 4" crushed cinder GI - 26 9.00$SY Trail, 4" top course GI - 27 12.00$SY Wall, retaining, concrete GI - 28 55.00$SF 1730 95,150.00 Wall, rockery GI - 29 15.00$SF 973 14,595.00 Page 3 of 9 SUBTOTAL 1,024.00 196,052.00 14,595.00 & Drainage Facilities *KCC 27A authorizes only one bond reduction. li-wks-sbqxls.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Right-of-way Right of Way Improvements Unit Price Unit Quant.Cost Quant.Cost Quant.Cost ROAD IMPROVEMENT No. AC Grinding, 4' wide machine < 1000sy RI - 1 30.00$SY AC Grinding, 4' wide machine 1000-2000syRI - 2 16.00$SY AC Grinding, 4' wide machine > 2000sy RI - 3 10.00$SY AC Removal/Disposal RI - 4 35.00$SY 234 8,190.00 Barricade, type III ( Permanent )RI - 6 56.00$LF Curb & Gutter, rolled RI - 7 17.00$LF Curb & Gutter, vertical RI - 8 12.50$LF 283 3,537.50 1468 18,350.00 Curb and Gutter, demolition and disposal RI - 9 18.00$LF Curb, extruded asphalt RI - 10 5.50$LF Curb, extruded concrete RI - 11 7.00$LF Sawcut, asphalt, 3" depth RI - 12 1.85$LF 904 1,672.40 Sawcut, concrete, per 1" depth RI - 13 3.00$LF Sealant, asphalt RI - 14 2.00$LF Shoulder, AC, ( see AC road unit price ) RI - 15 -$SY Shoulder, gravel, 4" thick RI - 16 15.00$SY Sidewalk, 4" thick RI - 17 38.00$SY 1170 44,460.00 Sidewalk, 4" thick, demolition and disposal RI - 18 32.00$SY Sidewalk, 5" thick RI - 19 41.00$SY Sidewalk, 5" thick, demolition and disposal RI - 20 40.00$SY Sign, handicap RI - 21 85.00$Each Striping, per stall RI - 22 7.00$Each Striping, thermoplastic, ( for crosswalk ) RI - 23 3.00$SF Striping, 4" reflectorized line RI - 24 0.50$LF Page 4 of 9 SUBTOTAL 13,399.90 62,810.00 Private & Drainage Facilities *KCC 27A authorizes only one bond reduction. li-wks-sbqxls.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Private Right-of-way Right of Way Improvements Unit Price Unit Quant.Cost Quant.Cost Quant.Cost ROAD 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$SY HMA 1/2" Overlay, 1.5"RS - 2 14.00$SY HMA 1/2" Overlay 2"RS - 3 18.00$SY HMA Road, 2", 4" rock, First 2500 SY RS - 4 28.00$SY 502 14,056.00 2253 63,084.00 HMA Road, 2", 4" rock, Qty. over 2500 SY RS - 5 21.00$SY HMA Road, 3", 9 1/2" Rock, First 2500 SY RS - 6 35.00$SY HMA Road, 3", 9 1/2" Rock, Qty Over 2500 SYRS - 7 42.00$SY Not Used RS - 8 Not Used RS - 9 HMA Road, 6" Depth, First 2500 SY RS - 10 33.10$SY HMA Road, 6" Depth, Qty. Over 2500 SY RS - 11 30.00$SY HMA 3/4" or 1", 4" Depth RS - 12 20.00$SY Gravel Road, 4" rock, First 2500 SY RS - 13 15.00$SY Gravel Road, 4" rock, Qty. over 2500 SY RS - 14 10.00$SY PCC Road (Add Under Write-Ins w/Design)RS - 15 Thickened Edge RS - 17 8.60$LF Page 5 of 9 SUBTOTAL 14,056.00 63,084.00 & Drainage Facilities *KCC 27A authorizes only one bond reduction. li-wks-sbqxls.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Private Right-of-way Right of Way Improvements Unit Price Unit Quant.Cost Quant.Cost Quant.Cost DRAINAGE (CPP = Corrugated Plastic Pipe, N12 or Equivalent) Access Road, R/D D - 1 21.00$SY 172 3,612.00 Bollards - fixed D - 2 240.74$Each Bollards - removable D - 3 452.34$Each * (CBs include frame and lid) CB Type I D - 4 1,500.00$Each 1 1,500.00 7 10,500.00 CB Type IL D - 5 1,750.00$Each 2 3,500.00 CB Type II, 48" diameter D - 6 2,300.00$Each 3 6,900.00 10 23,000.00 for additional depth over 4'D - 7 480.00$FT 33 15,840.00 CB Type II, 54" diameter D - 8 2,500.00$Each for additional depth over 4'D - 9 495.00$FT CB Type II, 60" diameter D - 10 2,800.00$Each 1 2,800.00 for additional depth over 4'D - 11 600.00$FT 4 2,400.00 CB Type II, 72" diameter D - 12 3,600.00$Each for additional depth over 4'D - 13 850.00$FT Through-curb Inlet Framework (Add)D - 14 400.00$Each 5 2,000.00 Cleanout, PVC, 4"D - 15 150.00$Each Cleanout, PVC, 6"D - 16 170.00$Each 16 2,720.00 Cleanout, PVC, 8"D - 17 200.00$Each Culvert, PVC, 4"D - 18 10.00$LF Culvert, PVC, 6"D - 19 13.00$LF 771 10,023.00 Culvert, PVC, 8"D - 20 15.00$LF Culvert, PVC, 12"D - 21 23.00$LF Culvert, CMP, 8"D - 22 19.00$LF Culvert, CMP, 12"D - 23 29.00$LF 452 13,108.00 873 25,317.00 Culvert, CMP, 15"D - 24 35.00$LF Culvert, CMP, 18"D - 25 41.00$LF Culvert, CMP, 24"D - 26 56.00$LF Culvert, CMP, 30"D - 27 78.00$LF Culvert, CMP, 36"D - 28 130.00$LF Culvert, CMP, 48"D - 29 190.00$LF Culvert, CMP, 60"D - 30 270.00$LF Culvert, CMP, 72"D - 31 350.00$LF Page 6 of 9 SUBTOTAL 21,508.00 88,969.00 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.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Private Right-of-way Right of Way Improvements DRAINAGE CONTINUED No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Culvert, Concrete, 8"D - 32 25.00$LF Culvert, Concrete, 12"D - 33 36.00$LF Culvert, Concrete, 15"D - 34 42.00$LF Culvert, Concrete, 18"D - 35 48.00$LF Culvert, Concrete, 24"D - 36 78.00$LF Culvert, Concrete, 30"D - 37 125.00$LF Culvert, Concrete, 36"D - 38 150.00$LF Culvert, Concrete, 42"D - 39 175.00$LF Culvert, Concrete, 48"D - 40 205.00$LF Culvert, CPP, 6"D - 41 14.00$LF Culvert, CPP, 8"D - 42 16.00$LF Culvert, CPP, 12"D - 43 24.00$LF Culvert, CPP, 15"D - 44 35.00$LF Culvert, CPP, 18"D - 45 41.00$LF Culvert, CPP, 24"D - 46 56.00$LF Culvert, CPP, 30"D - 47 78.00$LF Culvert, CPP, 36"D - 48 130.00$LF Ditching D - 49 9.50$CY Flow Dispersal Trench (1,436 base+)D - 50 28.00$LF French Drain (3' depth)D - 51 26.00$LF Geotextile, laid in trench, polypropylene D - 52 3.00$SY Mid-tank Access Riser, 48" dia, 6' deep D - 54 2,000.00$Each Pond Overflow Spillway D - 55 16.00$SY Restrictor/Oil Separator, 12"D - 56 1,150.00$Each 1 1150 Restrictor/Oil Separator, 15"D - 57 1,350.00$Each Restrictor/Oil Separator, 18"D - 58 1,700.00$Each Riprap, placed D - 59 42.00$CY Tank End Reducer (36" diameter)D - 60 1,200.00$Each Trash Rack, 12"D - 61 350.00$Each 3 1050 Trash Rack, 15"D - 62 410.00$Each Trash Rack, 18"D - 63 480.00$Each Trash Rack, 21"D - 64 550.00$Each Page 7 of 9 SUBTOTAL 2200 & Drainage Facilities *KCC 27A authorizes only one bond reduction. li-wks-sbqxls.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Future Public Private Right-of-way Right of Way Improvements Unit Price Unit Quant.Price Quant.Cost Quant.Cost PARKING LOT SURFACING No. 2" AC, 2" top course rock & 4" borrow PL - 1 21.00$SY NA NA 2" AC, 1.5" top course & 2.5" base coursePL - 2 28.00$SY NA NA 4" select borrow PL - 3 5.00$SY NA NA 1.5" top course rock & 2.5" base course PL - 4 14.00$SY NA NA UTILITY POLES & STREET LIGHTING Utility pole relocation costs must be accompanied by Franchise Utility's Cost Estimate Utility Pole(s) Relocation UP-1 Street Light Poles w/Luminaires UP-2 Each WRITE-IN-ITEMS (Such as detention/water quality vaults.)No. Perk Filter Vault WI - 1 31,100.00$Each 1 31,100.00 WI - 2 SY WI - 3 CY WI - 4 LF WI - 5 FT WI - 6 WI - 7 WI - 8 WI - 9 WI - 10 SUBTOTAL 31,100.00 SUBTOTAL (SUM ALL PAGES):49,987.90 444,215.00 27,338.00 30% CONTINGENCY & MOBILIZATION:14,996.37 133,264.50 8,201.40 GRANDTOTAL:64,984.27 577,479.50 35,539.40 COLUMN:B C D Page 8 of 9 Lump Sum & Drainage Facilities Not To Be Used For Roads Or Shoulders *KCC 27A authorizes only one bond reduction. li-wks-sbqxls.xls Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Original 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 Completed Total 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 0.30 Minimum is $2000.Minimum is $2000. Maintenance/Defect Bond* Total Minimum is $2000. NAME OF PERSON PREPARING BOND* REDUCTION:Date: * NOTE:The word "bond" as used in this document means a financial guarantee acceptable to King County. ** NOTE:KCC 27A authorizes right of way and site restoration bonds to be combined when both are required. The restoration requirement shall include the total cost for all TESC as a minimum, not a maximum. In addition, corrective work, both on- and off-site needs to be included. Quantities shall reflect worse case scenarios not just minimum requirements. For example, if a salmonid stream may be damaged, some estimated costs for restoration needs to be reflected in this amount. The 30% contingency and mobilization costs are computed in this quantity. *** NOTE:Per KCC 27A, total bond amounts remaining after reduction shall not be less than 30% of the original amount (T) or as revised by major design changes. REQUIRED BOND* AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY KING COUNTY 8/16/2016 (253) 838-6113 FINANCIAL GUARANTEE REQUIREMENTS PUBLIC ROAD & DRAINAGE MAINTENANCE/DEFECT BOND* Laura Bartenhagen, PE ESM Consulting Engineers, LLC 33400 8th Avenue South, Suite 205, Federal Way, WA 98003 PERFORMANCE BOND* AMOUNT 40111 MINIMUM BOND* AMOUNT REQUIRED FOR RECORDING OR TEMPORARY OCCUPANCY AT SUBSTANTIAL COMPLETION *** 8/16/2016 U16-001701 160,615.9$ Laura Bartenhagen, PE 91,603.2$ 64,984.3$ 577,479.5$ 230,881.9$ (B+C) x 0.25 = 156,587.5$ 35,539.4$ 769,606.4$ Page 9 of 9 li-wks-sbqxls.xls Check out the DDES Web site at www.kingcounty.gov/permits Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 8/16/2016 41 10. OPERATIONS AND MAINTENANCE MANUAL The Operations and Maintenance Manual is provided following this page. INSPECTION AND MAINTENANCE GUIDE oldcastlestormwater.com stormcapture.com(800) 579-8819 PERKFILTER™ November 4, 2015 Version 1 PerkFilter | Inspection and Maintenance Guide 2 11/4/2015_V1©2015 Oldcastle Precast, Inc. PerkFilter™ Media Filtration System Description The PerkFilter is a stormwater treatment device used to remove pollutants from urban runoff. Impervious surfaces and other urban and suburban landscapes generate a variety of contaminants that can enter stormwater and pollute downstream receiving waters. The PerkFilter is a media-filled cartridge filtration device designed to capture and retain sediment, gross solids, metals, nutrients, hydrocarbons, and trash and debris. As with any stormwater treatment system, the PerkFilter requires regular periodic maintenance to sustain optimum system performance. Function The PerkFilter is a water quality treatment system consisting of three chambers: an inlet chamber, a filter cartridge treatment chamber, and an outlet chamber (Figure 1). Stormwater runoff enters the inlet chamber through an inlet pipe, curb opening, or grated inlet. Gross solids are settled out and floating trash and debris are trapped in the inlet chamber. Pretreated flow is then directed to the treatment chamber through an opening in the baffle wall between the inlet chamber and treatment chamber. The treatment chamber contains media-filled filter cartridges (Figure 2) that use physical and chemical processes to remove pollutants. During a storm event, runoff pools in the treatment chamber before passing radially through the cylindrical cartridges from the outside surface, through the media for treatment, and into the center of the cartridge. At the center of the cartridge is a center tube assembly designed to distribute the hydraulic load evenly across the surface of the filter cartridge and control the treatment flow rate. The center tube assembly discharges treated flow through the false floor and into the outlet chamber. A draindown feature built into each cartridge allows the treatment chamber to dewater between storm events. Inlet pipe Filter cartridge treatment chamberPrecast concrete vault Inlet chamber Bypass assembly Concrete false floor Outlet chamber Outlet pipe Outlet hood Access Covers Figure 1. Schematic of the PerkFilter system. PerkFilter | Inspection and Maintenance Guide 3 11/4/2015_V1©2015 Oldcastle Precast, Inc. All PerkFilter systems include a high flow bypass assembly to divert flow exceeding the treatment capacity of the filter cartridges around the treatment chamber. The bypass assembly routes peak flow from the inlet chamber directly to the outlet chamber, bypassing the treatment chamber to prevent sediment and other captured pollutants from being scoured and re-entrained by high flow. Treated flow and bypass flow merge in the outlet chamber for discharge by a single outlet pipe. Configuration The PerkFilter structure may consist of a vault, manhole, or catch basin configuration. Catch basin units may be fabricated from concrete or steel. Internal components including the PerkFilter cartridges are manufactured from durable plastic and stainless steel components and hardware. All cartridges are 18 inches in diameter and are available in two heights: 12-inch and 18-inch. Cartridges may be used alone or may be stacked (Figure 3) to provide 24-inch and 30-inch combinations. The capacity of each cartridge or cartridge combination is dictated by the allowable operating rate of the media and the outer surface area of the cartridge. Thus, taller cartridges have greater treatment capacity than shorter cartridges but they also require more hydraulic drop across the system. Cartridges may be filled with a wide variety of media but the standard mix is composed of zeolite, perlite, and carbon (ZPC). Access to an installed PerkFilter system is typically provided by ductile iron castings or hatch covers. The location and number of access appurtenances is dependent on the size and configuration of the system. Vent tube Center tube assembly Outer media layer Inner media layer Connection to outlet chamber (with draindown) Outer screen Figure 2. Schematic of the PerkFilter cartridge. PerkFilter | Inspection and Maintenance Guide 4 11/4/2015_V1©2015 Oldcastle Precast, Inc. Single or bottom stacked cartridge Inner interconnector coupling (2 “ dia.) Top stacked cartridge Vent tube (4 “ dia.) Outer interconnector coupling (4 “ dia.) Urethane bottom cap Slip coupler (2 “ dia.) Figure 3. Schematic of stacked cartridges and connector components. PerkFilter | Inspection and Maintenance Guide 5 11/4/2015_V1©2015 Oldcastle Precast, Inc. Maintenance Overview State and local regulations require all stormwater management systems to be inspected on a regular basis and maintained as necessary to ensure performance and protect downstream receiving waters. Maintenance prevents excessive pollutant buildup that can limit system performance by reducing the operating capacity and increasing the potential for scouring of pollutants during periods of high flow. Inspection and Maintenance Frequency The PerkFilter should be inspected on a regular basis, typically twice per year, and maintained as required. Initially, inspections of a new system should be conducted more frequently to help establish an appropriate site-specific inspection frequency. The maintenance frequency will be driven by the amount of runoff and pollutant loading encountered by a given system. In most cases, the optimum maintenance interval will be one to three years. Inspection and maintenance activities should be performed only during dry weather periods. Inspection Equipment The following equipment is helpful when conducting PerkFilter inspections: • Recording device (pen and paper form, voice recorder, iPad, etc.) • Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.) • Traffic control equipment (cones, barricades, signage, flagging, etc.) • Socket and wrench for bolt-down access covers • Manhole hook or pry bar • Flashlight • Tape measure • Measuring stick or sludge sampler • Long-handled net (optional) Inspection Procedures PerkFilter inspections are visual and may be conducted from the ground surface without entering the unit. To complete an inspection, safety measures including traffic control should be deployed before the access covers are removed. Once the covers have been removed, the following items should be checked and recorded (see form provided at the end of this document) to determine whether maintenance is required: • Inspect the internal components and note whether there are any broken or missing parts. In the unlikely event that internal parts are broken or missing, contact Oldcastle Stormwater Solutions at (800) 579-8819 to determine appropriate corrective action. • Note whether the inlet pipe is blocked or obstructed. The outlet pipe is covered by a removable outlet hood and cannot be observed without entering the unit. PerkFilter | Inspection and Maintenance Guide 6 11/4/2015_V1©2015 Oldcastle Precast, Inc. • Observe, quantify, and record the accumulation of floating trash and debris in the inlet chamber. The significance of accumulated floating trash and debris is a matter of judgment. A long-handled net may be used to retrieve the bulk of trash and debris at the time of inspection if full maintenance due to accumulation of floating oils or settled sediment is not yet warranted. • Observe, quantify, and record the accumulation of oils in the inlet chamber. The significance of accumulated floating oils is a matter of judgment. However, if there is evidence of an oil or fuel spill, immediate maintenance by appropriate certified personnel is warranted. • Observe, quantify, and record the average accumulation of sediment in the inlet chamber and treatment chamber. A calibrated dipstick, tape measure, or sludge sampler may be used to determine the amount of accumulated sediment in each chamber. The depth of sediment may be determined by calculating the difference between the measurement from the rim of the PerkFilter to the top of the accumulated sediment and the measurement from the rim of the PerkFilter to the bottom of the PerkFilter structure. Finding the top of the accumulated sediment below standing water takes some practice and a light touch, but increased resistance as the measuring device is lowered toward the bottom of the unit indicates the top of the accumulated sediment. • Finally, observe, quantify, and record the amount of standing water in the treatment chamber around the cartridges. If standing water is present, do not include the depth of sediment that may have settled out below the standing water in the measurement. Maintenance Triggers Maintenance should be scheduled if any of the following conditions are identified during the inspection: • Internal components are broken or missing. • Inlet piping is obstructed. • The accumulation of floating trash and debris that cannot be retrieved with a net and/or oil in the inlet chamber is significant. • There is more than 6” of accumulated sediment in the inlet chamber. • There is more than 4” of accumulated sediment in the treatment chamber. • There is more than 4” of standing water in the treatment chamber more than 24 hours after end of rain event. • A hazardous material release (e.g. automotive fluids) is observed or reported. • The system has not been maintained for 3 years (wet climates) to 5 years (dry climates). Maintenance Equipment The following equipment is helpful when conducting PerkFilter maintenance: • Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.) • Traffic control equipment (cones, barricades, signage, flagging, etc.) • Socket and wrench for bolt-down access covers • Manhole hook or pry bar • Confined space entry equipment, if needed PerkFilter | Inspection and Maintenance Guide 7 11/4/2015_V1©2015 Oldcastle Precast, Inc. • Flashlight • Tape measure • 9/16” socket and wrench to remove hold-down struts and filter cartridge tops • Replacement filter cartridges • Vacuum truck with water supply and water jet Contact Oldcastle Stormwater Solutions at (800) 579-8819 for replacement filter cartridges. A lead time of four weeks is recommended. Maintenance Procedures Maintenance should be conducted during dry weather when no flow is entering the system. Confined space entry is necessary to maintain vault and manhole PerkFilter configurations. Only personnel that are OSHA Confined Space Entry trained and certified may enter underground structures. Confined space entry is not required for catch basin PerkFilter configurations. Once safety measures such as traffic control are deployed, the access covers may be removed and the following activities may be conducted to complete maintenance: • Remove floating trash, debris, and oils from the water surface in the inlet chamber using the extension nozzle on the end of the boom hose of the vacuum truck. Continue using the vacuum truck to completely dewater the inlet chamber and evacuate all accumulated sediment from the inlet chamber. Some jetting may be required to fully remove sediment. The inlet chamber does not need to be refilled with water after maintenance is complete. The system will fill with water when the next storm event occurs. • Remove the hold-down strut from each row of filter cartridges and then remove the top of each cartridge (the top is held on by four 9/16” bolts) and use the vacuum truck to evacuate the spent media. When empty, the spent cartridges may be easily lifted off their slip couplers and removed from the vault. The couplers may be left inserted into couplings cast into the false floor to prevent sediment and debris from being washed into the outlet chamber during washdown. • Once all the spent cartridges have been removed from the structure, the vacuum truck may be used to evacuate all accumulated sediment from the treatment chamber. Some jetting may be required to fully remove sediment. Take care not to wash sediment and debris through the openings in the false floor and into the outlet chamber. All material removed from the PerkFilter during maintenance including the spent media must be disposed of in accordance with local, state, and/or federal regulations. In most cases, the material may be handled in the same manner as disposal of material removed from sumped catch basins or manholes. • Place a fresh cartridge in each cartridge position using the existing slip couplers and urethane bottom caps. If the vault is equipped with stacked cartridges, the existing outer and inner interconnector couplers must be used between the stacked cartridges to provide hydraulic connection. Transfer the existing vent tubes from the spent cartridges to the fresh cartridges. Finally, refit the struts to hold the fresh cartridges in place. • Securely replace access covers, as appropriate. • Make arrangements to return the empty spent cartridges to Oldcastle Stormwater Solutions. PerkFilter | Inspection and Maintenance Guide 8 11/4/2015_V1©2015 Oldcastle Precast, Inc. 7 | Page-Dual Vortex Separator -Inspection and Maintenance Guide Oldcastle Stormwater Solutions 360 Sutton Place Santa Rosa, CA 95407 (800) 579-8819 www.oldcastlestormwater.com PerkFilter Inspection and Maintenance Log Location _____________________________________________________________ Structure Configuration and Size: Inspection Date ______________ □ Vault _____ feet x _____ feet □ Manhole _____diameter □ Catch Basin _____ feet x _____ feet Number and Height of Cartridges: Count _____each □ 12” □ 18” □ 24” □ 30” Media Type: □ ZPC □ Perlite □ Other _______________ Condition of Internal Components □ Good □ Damaged □ Missing Notes: Inlet Pipe Blockage or Obstruction □ Yes □ No Notes: Floating Trash and Debris □ Significant □ Not Significant Notes: Floating Oils □ Significant □ Not Significant □ Spill Notes: Sediment Depth in Inlet Chamber □ Inches of Sediment: __________ Notes: Sediment Depth in Treatment Chamber □ Inches of Sediment: __________ Notes: 8 | Page-Dual Vortex Separator -Inspection and Maintenance Guide Oldcastle Stormwater Solutions 360 Sutton Place Santa Rosa, CA 95407 (800) 579-8819 www.oldcastlestormwater.com Standing Water in Treatment Chamber □ Inches of Standing Water: __________ Notes: Maintenance Required □ Yes –Schedule Maintenance □ No –Inspect Again in _____ Months APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-15 NO. 10 – GATES/BOLLARDS/ACCESS BARRIERS Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Missing gate. Gates in place. Broken or missing hinges such that gate cannot be easily opened and closed by a maintenance person. Hinges intact and lubed. Gate is working freely. Gate is out of plumb more than 6 inches and more than 1 foot out of design alignment. Gate is aligned and vertical. Damaged or missing members Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in place. Locking mechanism does not lock gate Locking device missing, no-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Chain Link Fencing Gate Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size. Damaged or missing cross bar Cross bar does not swing open or closed, is missing or is bent to where it does not prevent vehicle access. Cross bar swings fully open and closed and prevents vehicle access. Locking mechanism does not lock gate Locking device missing, no-functioning or does not link to all parts. Locking mechanism prevents opening of gate. Bar Gate Support post damaged Support post does not hold cross bar up. Cross bar held up preventing vehicle access into facility. Damaged or missing Bollard broken, missing, does not fit into support hole or hinge broken or missing. No access for motorized vehicles to get into facility. Bollards Does not lock Locking assembly or lock missing or cannot be attached to lock bollard in place. No access for motorized vehicles to get into facility. Dislodged Boulders not located to prevent motorized vehicle access. No access for motorized vehicles to get into facility. Boulders Circumvented Motorized vehicles going around or between boulders. No access for motorized vehicles to get into facility. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-16 NO. 11 – GROUNDS (LANDSCAPING) Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Trash or litter Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Site Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Hazard Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees and Shrubs Damaged Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-17 NO. 12 – ACCESS ROADS Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Trash and debris exceeds 1 cubic foot per 1,000 square feet (i.e., trash and debris would fill up one standards size garbage can). Roadway drivable by maintenance vehicles. Trash and debris Debris which could damage vehicle tires or prohibit use of road. Roadway drivable by maintenance vehicles. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Any obstruction which reduces clearance above road surface to less than 14 feet. Roadway overhead clear to 14 feet high. Site Blocked roadway Any obstruction restricting the access to a 10- to 12 foot width for a distance of more than 12 feet or any point restricting access to less than a 10 foot width. At least 12-foot of width on access road. Erosion, settlement, potholes, soft spots, ruts Any surface defect which hinders or prevents maintenance access. Road drivable by maintenance vehicles. Road Surface Vegetation on road surface Trees or other vegetation prevent access to facility by maintenance vehicles. Maintenance vehicles can access facility. Erosion Erosion within 1 foot of the roadway more than 8 inches wide and 6 inches deep. Shoulder free of erosion and matching the surrounding road. Shoulders and Ditches Weeds and brush Weeds and brush exceed 18 inches in height or hinder maintenance access. Weeds and brush cut to 2 inches in height or cleared in such a way as to allow maintenance access. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Modular Grid Pavement Damaged or missing Access surface compacted because of broken on missing modular block. Access road surface restored so road infiltrates. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-2 NO. 1 – DETENTION PONDS Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Site Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Top or Side Slopes of Dam, Berm or Embankment Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Sediment accumulation Accumulated sediment that exceeds 10% of the designed pond depth. Sediment cleaned out to designed pond shape and depth; pond reseeded if necessary to control erosion. Storage Area Liner damaged (If Applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Inlet/Outlet Pipe. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. Emergency Overflow/Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil on the spillway. Spillway restored to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-7 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Trash and debris Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Damage to frame and/or top slab Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks in walls or bottom Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Structure Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. FROP-T Section Damage Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-8 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Damaged or missing Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Orifice Plate Obstructions Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Obstructions Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Overflow Pipe Deformed or damaged lip Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Inlet/Outlet Pipe Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Metal Grates (If Applicable) Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Manhole Cover/Lid Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-9 NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Sediment Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Trash and debris Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Damage to frame and/or top slab Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and structurally sound. Cracks in walls or bottom Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Structure Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Inlet/Outlet Pipe Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-10 NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Metal Grates (Catch Basins) Damaged or missing Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Manhole Cover/Lid Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-11 NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Pipes Damaged Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Ditches Rock lining out of place or missing (If Applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-12 NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS) Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed. Trash and debris Trash or debris plugging more than 20% of the area of the barrier. Barrier clear to receive capacity flow. Site Sediment accumulation Sediment accumulation of greater than 20% of the area of the barrier Barrier clear to receive capacity flow. Structure Cracked broken or loose Structure which bars attached to is damaged - pipe is loose or cracked or concrete structure is cracked, broken of loose. Structure barrier attached to is sound. Bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inche spacing. Bars are bent out of shape more than 3 inches. Bars in place with no bends more than ¾ inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars Damaged or missing bars Bars are loose and rust is causing 50% deterioration to any part of barrier. Repair or replace barrier to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 2009 Surface Water Design Manual – Appendix A 1/9/2009 A-13 NO. 8 – ENERGY DISSIPATERS Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed. Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or debris. Site Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Rock Pad Missing or moved Rock Only one layer of rock exists above native soil in area five square feet or larger or any exposure of native soil. Rock pad prevents erosion. Pipe plugged with sediment Accumulated sediment that exceeds 20% of the design depth. Pipe cleaned/flushed so that it matches design. Not discharging water properly Visual evidence of water discharging at concentrated points along trench (normal condition is a “sheet flow” of water along trench). Water discharges from feature by sheet flow. Perforations plugged. Over 1/4 of perforations in pipe are plugged with debris or sediment. Perforations freely discharge flow. Water flows out top of “distributor” catch basin. Water flows out of distributor catch basin during any storm less than the design storm. No flow discharges from distributor catch basin. Dispersion Trench Receiving area over-saturated Water in receiving area is causing or has potential of causing landslide problems. No danger of landslides. Damaged mesh Mesh of gabion broken, twisted or deformed so structure is weakened or rock may fall out. Mesh is intact, no rock missing. Corrosion Gabion mesh shows corrosion through more than ¼ of its gage. All gabion mesh capable of containing rock and retaining designed form. Collapsed or deformed baskets Gabion basket shape deformed due to any cause. All gabion baskets intact, structure stands as designed. Gabions Missing rock Any rock missing that could cause gabion to loose structural integrity. No rock missing. Worn or damaged post, baffles or side of chamber Structure dissipating flow deteriorates to ½ or original size or any concentrated worn spot exceeding one square foot which would make structure unsound. Structure is in no danger of failing. Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch or any evidence of soil entering the structure through cracks, or maintenance inspection personnel determines that the structure is not structurally sound. Manhole/chamber is sealed and structurally sound. Manhole/Chamber Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No soil or water enters and no water discharges at the joint of inlet/outlet pipes. APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES 1/9/2009 2009 Surface Water Design Manual – Appendix A A-14 NO. 9 – FENCING Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12- 18 inches wide permitting access through an opening under a fence. No access under the fence. Missing or damaged parts Missing or broken boards, post out of plumb by more than 6 inches or cross members broken No gaps on fence due to missing or broken boards, post plumb to within 1½ inches, cross members sound. Weakened by rotting or insects Any part showing structural deterioration due to rotting or insect damage All parts of fence are structurally sound. Wood Posts, Boards and Cross Members Damaged or failed post foundation Concrete or metal attachments deteriorated or unable to support posts. Post foundation capable of supporting posts even in strong wind. Post out of plumb more than 6 inches. Post plumb to within 1½ inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and fabric) more than 1 foot out of design alignment. Fence is aligned and meets design standards. Damaged parts Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or protective coating Part or parts that have a rusting or scaling condition that has affected structural adequacy. Structurally adequate posts or parts with a uniform protective coating. Metal Posts, Rails and Fabric Openings in fabric Openings in fabric are such that an 8-inch diameter ball could fit through. Fabric mesh openings within 50% of grid size.