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Home My WebLink AboutRS_Preliminary_TIR_180330_v1 TECHNICAL INFORMATION REPORT OB RENTON - PARKING LOT EXPANSION 800 S.W. 16th St. Renton, Washington 98059 Prepared for: OB Renton Properties, LLC S.W. 16th St. Renton, Washington 98055 October 20, 2017 Our Job No. 18557 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 FAX BRANCH OFFICES  TUMWATER, WA  LONG BEACH, CA  ROSEVILLE, CA  SAN DIEGO, CA www.barghausen.com Stormwater Site Plan OB Renton - Parking Lot Expansion Renton, Washington Our Job No. 18557 TABLE OF CONTENTS 1.0 PROJECT OVERVIEW Figure 1 – Technical Information Report (TIR) Worksheet Figure 2 – Site Location Figure 3 – Drainage Basins, Subbasins, and Site Characteristics Figure 4 – Soils 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Core Requirements 2.2 Analysis of the Special Requirements 3.0 OFF-SITE ANALYSIS 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Existing Site Hydrology B. Developed Site Hydrology C. Performance Standards D. Flow Control System E. Water Quality System 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 6.0 SPECIAL REPORTS AND STUDIES 7.0 OTHER PERMITS 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENTION (CSWPP) ANALYSIS AND DESIGN A. Erosion and Sediment Control (ESC) Plan Analysis and Design B. Stormwater Pollution Prevention and Spill (SWPPS) Plan Design 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 10.0 OPERATIONS AND MAINTENANCE MANUAL Tab 1.0 1.0 PROJECT OVERVIEW 1.0 PROJECT OVERVIEW The redevelopment project in consideration is a parking lot expansion . The total area of disturbance is ~16,500 square feet, located within a parcel of ~3.25 acres. The proposed project is located in a portion of the NW 1/4 of the SE 1/4 of sec. 24, 23 N. RGE 4 East, W. M. The tax parcel associated with this project is 334040-6430-02. The redevelopment project will utilize porous pavement underlain with a base course of crushed rock to promote infiltration. Existing conditions are composed of lawn and trees. There are no critical areas located on site. A class 4 stream is located on the northern border of the property but the construction will not occur within 100 feet of the stream. While the parcel contains a 100-year floodplain it is not located within the project limits. A slope of greater than 15% is located to the North of the site, within 200 feet of the proposed permeable pavement. Therefore, this project must be approved by a geotechnical engineer or engineering geologist unless otherwise approved by the DPER staff geologist. FIGURE 1 TECHNICAL INFORMATION REPORT (TIR) WORKSHEET KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner ___________________________ Phone _________________________________ Address _______________________________ _______________________________________ Project Engineer _________________________ Company ______________________________ Phone _________________________________ Project Name _________________________ DPER Permit # ________________________ Location Township ______________ Range ________________ Section ________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS  Landuse (e.g.,Subdivision / Short Subd. / UPD)  Building (e.g.,M/F / Commercial / SFR)  Clearing and Grading  Right-of-Way Use  Other _______________________  DFW HPA  COE 404  DOE Dam Safety  FEMA Floodplain  COE Wetlands  Other ________  Shoreline Management  Structural Rockery/Vault/_____  ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final:  Full  Targeted  Simplified  Large Project  Directed __________________ __________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final:  Full  Modified  Simplified __________________ __________________ __________________ Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Experimental / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: ______________________ 2016 Surface Water Design Manual 4/24/2016 1 Shuttle Express (425) 981-7000 800 SW 16th St. Renton, WA 98057 Ali Sadr Barghausen Consulting Engineers (425) 251-6222 ext. 7432 OB RENTON 23N RGE. 4 EAST 24 800 SW 16th St. Renton, WA 10/24/17 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: KCSWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan : ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: ____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS  River/Stream ________________________  Lake ______________________________  Wetlands ____________________________  Closed Depression ____________________  Floodplain ___________________________  Other _______________________________ _______________________________  Steep Slope __________________________  Erosion Hazard _______________________  Landslide Hazard ______________________  Coal Mine Hazard ______________________  Seismic Hazard _______________________  Habitat Protection ______________________  _____________________________________ Part 10 SOILS Soil Type _________________ _________________ _________________ _________________ Slopes _________________ _________________ _________________ _________________ Erosion Potential _________________ _________________ _________________ _________________  High Groundwater Table (within 5 feet)  Other ________________________________  Sole Source Aquifer  Seeps/Springs  Additional Sheets Attached 2016 Surface Water Design Manual 4/24/2016 2 Renton Urban Land (Fill) KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE  Core 2 – Offsite Analysis_________________  Sensitive/Critical Areas__________________  SEPA________________________________  LID Infeasibility________________________  Other________________________________  _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________  Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 8 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Level: 1 / 2 / 3 or Exemption Number ____________ Flow Control BMPs _______________________________ Conveyance System Spill containment located at: _________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. ______________________ Landscape Management Plan: Yes / No Special Requirements (as applicable): Area Specific Drainage Requirements Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): ______________ Datum: Flood Protection Facilities Describe: 2016 Surface Water Design Manual 4/24/2016 3 None Peak Rate Flow Control Standard (Existing Site Conditions) Permeable Pavement KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Source Control (comm ercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-use Site: Yes / No Treatment BMP: ________________________________ Maintenance Agreement: Yes / No with whom? ____________________________________ Other Drainage Structures Describe: Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION  Clearing Limits  Cover Measures  Perimeter Protection  Traffic Area Stabilization  Sediment Retention  Surface Water Collection  Dewatering Control  Dust Control  Flow Control  Protection of Flow Control BMP Facilities (existing and proposed)  Maintain BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION  Stabilize exposed surfaces  Remove and restore Temporary ESC Facilities  Clean and remove all silt and debris, ensure operation of Permanent Facilities, restore operation of Flow Control BMP Facilities as necessary  Flag limits of SAO and open space preservation areas  Other ______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description  Detention  Infiltration  Regional Facility  Shared Facility  Flow Control BMPs  Other ________________ ________________ ________________ ________________ ________________ ________________  Vegetated Flowpath  Wetpool  Filtration  Oil Control  Spill Control  Flow Control BMPs  Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ 2016 Surface Water Design Manual 4/24/2016 4 Permeable Pavement Permeable Pavement Permeable Pavement KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS  Drainage Easement  Covenant  Native Growth Protection Covenant  Tract  Other ___________________________  Cast in Place Vault  Retaining Wall  Rockery > 4’ High  Structural on Steep Slope  Other ______________________________ Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date 2016 Surface Water Design Manual 4/24/2016 5 FIGURE 2 SITE LOCATION FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS WESTERN PERMEABLE PAVEMENT 0.46 AC EASTERN (NORTH) PERMEABLE PAVEMENT = 0.11 AC TOTAL IMPERMEABLE PAVEMENT = 0.10 AC LANDSCAPE = 0.02 AC EASTERN (SOUTH) PERMEABLE PAVEMENT = 0.11 AC TOTAL IMPERMEABLE PAVEMENT = 0.10 AC LANDSCAPE = 0.02 AC FIGURE 4 SOILS Soil Map—King County Area, Washington (OB RENTON - PARKING LOT EXPANSION) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/23/2017 Page 1 of 352572405257260525728052573005257320525734052573605257240525726052572805257300525732052573405257360558040558060558080558100558120558140558160558180558200558220558240 558040 558060 558080 558100 558120 558140 558160 558180 558200 558220 558240 47° 28' 1'' N 122° 13' 47'' W47° 28' 1'' N122° 13' 37'' W47° 27' 57'' N 122° 13' 47'' W47° 27' 57'' N 122° 13' 37'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 45 90 180 270 Feet 0 10 20 40 60 Meters Map Scale: 1:981 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. 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: 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 12, Sep 8, 2016 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—Oct 6, 2013 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 (OB RENTON - PARKING LOT EXPANSION) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/23/2017 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ur Urban land 4.3 100.0% Totals for Area of Interest 4.3 100.0% Soil Map—King County Area, Washington OB RENTON - PARKING LOT EXPANSION Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/23/2017 Page 3 of 3 Tab 2.0 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Core Requirements Core Requirement No. 1: Discharge at the Natural Location Response: The site currently discharges any runoff which is not infiltrated by the existing landscape areas to the city storm sewer. The developed conditions will mimic this pattern, by infiltrating runoff via permeable pavement, but allowing for overflow to the city storm sewer system. Core Requirement No. 2: Off-Site Analysis Response: This project is exempt from this requirement since the project does not change the rate, volume, duration or location of discharge to and from the project site, i.e. the proposed method of stormwater management will match the existing hydrologic conditions of full-infiltration of runoff. Core Requirement No. 3: Flow Control Response: Flow control is provided via infiltration. Core Requirement No. 4: Conveyance System Response: All storm runoff from proposed areas are designed to sheet flow and infiltrate with an emergency overflow connected to the city storm sewer. There are no conveyance pipes in the proposed design, aside from the emergency overflow. Core Requirement No. 5: Construction Stormwater Pollution Prevention Response: The SWPPP will be provided with the final construction drawings. Core Requirement No. 6: Maintenance and Operations Response: A Maintenance and Operations manual will be provided with final construction drawings. Core Requirement No. 7: Financial Guarantees and Liability Response: Financial guarantees will be provided by developer/owner as required. Core Requirement No. 8: Water Quality Response: Proposed pollution generating impervious surface (PGIS) will be greater than 5,000 square feet. Therefore, water quality treatment is required. The soils beneath the permeable pavement are capable of providing this treatment. Core Requirement No. 9: Flow Control BMP's Response: The runoff from the entire development will be infiltrated with permeable pavement, underlain by soils capable of providing water quality treatment. 2.2 Analysis of the Special Requirements Special Requirement No. 1: Other Adopted Area-Specific Requirements. Response: There is no adopted area specific requirements in the area of this project. Special Requirement No. 2: Flood Hazard Area Delineation. Response: This project is exempt from this requirement because there is no floodplain located within the project limits. Special Requirement No. 3: Flood Protection Facilities. Response: There are no flood proposed protection facilities associated with this project. Special Requirement No. 4: Source Control. Response: All known, available and reasonable source control BMP's will be applied to this project. Special Requirement No. 5: Oil Control. Response: This project does not trigger requirements for oil control. Special Requirement No. 6: Aquifer Protection Area Response: Project site is not located in an aquifer protection Area. Tab 3.0 3.0 OFF-SITE ANALYSIS 3.0 OFF-SITE ANALYSIS Not deemed necessary due to full infiltration of Stormwater runoff, but will be provided with the final Technical Information Report if requested by the City of Renton. Tab 4.0 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Existing Site Hydrology There is no on-site conveyance system. The existing drainage system captures sheet flow from the pavement, and infiltrates in the existing grass area. Groundwater seepage was observed at approximately 11.0 and 7.5 feet below the ground surface. There is existing landscaping around the perimeter of the site. Vegetation is primarily composed of lawn, and ~10 trees. B. Developed Site Hydrology Stormwater from the developed site will infiltrate through the porous asphalt. One section of asphalt on the West of the site will be composed co mpletely of permeable pavement. Another section of asphalt on the Southwest of the site is composed of both pervious and impervious concrete, with coverages of ~9,950 sq. ft and ~8,320 sq. ft, respectively. The drive aisle will be impervious, and runoff from this section will flow to the parking stalls, which will be pervious, underlain by a free-draining gravel layer. The grading has been designed so that approximately half of the runoff from the drive aisle will be directed to two, separate but equally sized permeable pavement sections. Overflow for a 0.5 acre parcel of the existing parking area adjacent to the permeable pavement is composed of a gravel filled trench drain connected to the City's system in SW 16th St. Flows up to and including the 50 year flood event are capable of being infiltrated by the permeable pavement. The additional runoff produced under forested conditions during the 100-year event would be negligible (0.004 cfs per the WWHM report), and would either be infiltrated or conveyed by the trench drain to the city storm sewer system. C. Performance Standards The permeable pavement has been designed in accordance with standards presented in section C.2.7.4 of the 2017 Renton Stormwater Design Manual, as well as Chapter 5, Section IN.06, on page 5-161, of the 2014 WSDOT Highway Runoff Manual, and Section 5.4 of the 2015 WSDOT Pavement Policy reference book. The geotech report recommends a 6 inch layer of permeable HMA pavement, underlain by at least 12 inches of free draining gravel base. These recommendations are reflected in the accompanying WWHM reports, as well as the detail for the permeable pave ment specified in the civil planset. The infiltration rate of the subgrade soil was measured at 6.92 in-hr, but was modelled at 0.5 in/hr per the Geotech report, to ensure representation of the long-term infiltration rate. The minimum required depth of free-draining sand or gravel base required under the porous concrete surface is 6 inches per the 2017 RSWDM and WSDOT Pavement Policy, but a layer of 12 inches in thickness is specified per the geotech report. Typical void space in these base layers range from 20-40%. For the purposes of modelling, a relatively conservative estimate of 30% void space was utilized. This depth and porosity of subsurface material was shown to provide sufficient storage and infiltration for all flows, up to and including the 50-year precipitation event. D. Flow Control System No flow control system is required since the permeable pavement, a flow control BMP, has been designed so that 100% of runoff , up to and including the 50 year event, is infiltrated. A WWHM model report is provided in the following pages to validate the effectiveness of the specified permeable pavement design. E. Water Quality System The water quality system is composed of a subgrade of soil beneath the permeable pavement section. Since the soils at the site exhibit an infiltration rate of greater than 3.0 inches per hour, to meet the required water quality treatment goals, the subgrade soil must exhibit a cation exchange capacity (CEC) of at least 5 milliequivalents/gram of dry soil or greater. If the native soils do not provide this level of treatment, then a soil layer of 18" minimum thickness must be amended with organic matter to provide the required CEC. PERVIOUS PAVEMENT DETAIL EXISTING CONDITIONS MAP WESTERN PERMEABLE PAVEMENT CALCULATIONS WWHM2012 PROJECT REPORT 18557 - Infiltration West SSD 10/25/2017 11:05:29 AM Page 2 General Model Information Project Name:18557 - Infiltration West SSD Site Name:OB Renton Site Address:800 SW 16th St. City:Renton Report Date:10/25/2017 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2017/04/14 Version:4.2.13 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 18557 - Infiltration West SSD 10/25/2017 11:05:29 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 0.46 Pervious Total 0.46 Impervious Land Use acre Impervious Total 0 Basin Total 0.46 Element Flows To: Surface Interflow Groundwater 18557 - Infiltration West SSD 10/25/2017 11:05:29 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre PARKING FLAT 0.46 Impervious Total 0.46 Basin Total 0.46 Element Flows To: Surface Interflow Groundwater SSD Table 1 SSD Table 1 18557 - Infiltration West SSD 10/25/2017 11:05:29 AM Page 6 Mitigated Routing SSD Table 1 Depth:1 ft. Element Flows To: Outlet 1 Outlet 2 SSD Table Hydraulic Table Stage Area Volume Infilt (feet) (ac.) (ac-ft.) Manual (cfs) NotUsed NotUsed NotUsed 0.100 0.460 0.014 0.000 0.232 0.000 0.000 0.000 0.200 0.460 0.028 0.000 0.232 0.000 0.000 0.000 0.300 0.460 0.041 0.000 0.232 0.000 0.000 0.000 0.400 0.460 0.055 0.000 0.232 0.000 0.000 0.000 0.500 0.460 0.069 0.000 0.232 0.000 0.000 0.000 0.600 0.460 0.083 0.000 0.232 0.000 0.000 0.000 0.700 0.460 0.097 0.000 0.232 0.000 0.000 0.000 0.800 0.460 0.110 0.000 0.232 0.000 0.000 0.000 0.900 0.460 0.124 0.000 0.232 0.000 0.000 0.000 1.000 0.460 0.138 0.000 0.232 0.000 0.000 0.000 18557 - Infiltration West SSD 10/25/2017 11:05:29 AM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.46 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.46 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.013524 5 year 0.021241 10 year 0.025613 25 year 0.030246 50 year 0.033113 100 year 0.035551 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.013 0.000 1950 0.017 0.000 1951 0.030 0.000 1952 0.009 0.000 1953 0.008 0.000 1954 0.012 0.000 1955 0.019 0.000 1956 0.015 0.000 1957 0.012 0.000 1958 0.013 0.000 18557 - Infiltration West SSD 10/25/2017 11:06:00 AM Page 8 1959 0.012 0.000 1960 0.020 0.000 1961 0.011 0.000 1962 0.007 0.000 1963 0.010 0.000 1964 0.013 0.000 1965 0.009 0.000 1966 0.009 0.000 1967 0.018 0.000 1968 0.011 0.000 1969 0.011 0.000 1970 0.009 0.000 1971 0.010 0.000 1972 0.022 0.000 1973 0.010 0.000 1974 0.011 0.000 1975 0.015 0.000 1976 0.011 0.000 1977 0.001 0.000 1978 0.009 0.000 1979 0.006 0.000 1980 0.021 0.000 1981 0.008 0.000 1982 0.016 0.000 1983 0.014 0.000 1984 0.009 0.000 1985 0.005 0.000 1986 0.023 0.000 1987 0.021 0.000 1988 0.008 0.000 1989 0.005 0.000 1990 0.043 0.000 1991 0.026 0.000 1992 0.010 0.000 1993 0.010 0.000 1994 0.004 0.000 1995 0.015 0.000 1996 0.032 0.000 1997 0.026 0.000 1998 0.006 0.000 1999 0.025 0.000 2000 0.010 0.000 2001 0.002 0.000 2002 0.011 0.000 2003 0.015 0.000 2004 0.019 0.000 2005 0.014 0.000 2006 0.016 0.000 2007 0.032 0.000 2008 0.042 0.000 2009 0.020 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0434 0.0000 2 0.0415 0.0000 3 0.0322 0.0000 18557 - Infiltration West SSD 10/25/2017 11:06:00 AM Page 9 4 0.0317 0.0000 5 0.0298 0.0000 6 0.0265 0.0000 7 0.0261 0.0000 8 0.0248 0.0000 9 0.0234 0.0000 10 0.0222 0.0000 11 0.0210 0.0000 12 0.0207 0.0000 13 0.0204 0.0000 14 0.0201 0.0000 15 0.0189 0.0000 16 0.0186 0.0000 17 0.0184 0.0000 18 0.0166 0.0000 19 0.0162 0.0000 20 0.0160 0.0000 21 0.0150 0.0000 22 0.0148 0.0000 23 0.0148 0.0000 24 0.0146 0.0000 25 0.0145 0.0000 26 0.0136 0.0000 27 0.0134 0.0000 28 0.0133 0.0000 29 0.0128 0.0000 30 0.0119 0.0000 31 0.0117 0.0000 32 0.0115 0.0000 33 0.0115 0.0000 34 0.0115 0.0000 35 0.0114 0.0000 36 0.0112 0.0000 37 0.0109 0.0000 38 0.0107 0.0000 39 0.0105 0.0000 40 0.0105 0.0000 41 0.0101 0.0000 42 0.0101 0.0000 43 0.0099 0.0000 44 0.0097 0.0000 45 0.0094 0.0000 46 0.0094 0.0000 47 0.0093 0.0000 48 0.0091 0.0000 49 0.0089 0.0000 50 0.0088 0.0000 51 0.0084 0.0000 52 0.0082 0.0000 53 0.0076 0.0000 54 0.0071 0.0000 55 0.0060 0.0000 56 0.0057 0.0000 57 0.0053 0.0000 58 0.0053 0.0000 59 0.0035 0.0000 60 0.0019 0.0000 61 0.0013 0.0000 18557 - Infiltration West SSD 10/25/2017 11:06:00 AM Page 11 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0068 17547 0 0 Pass 0.0070 16164 0 0 Pass 0.0073 14964 0 0 Pass 0.0076 13851 0 0 Pass 0.0078 12814 0 0 Pass 0.0081 11811 0 0 Pass 0.0084 10898 0 0 Pass 0.0086 10119 0 0 Pass 0.0089 9383 0 0 Pass 0.0092 8731 0 0 Pass 0.0094 8145 0 0 Pass 0.0097 7593 0 0 Pass 0.0100 7058 0 0 Pass 0.0102 6590 0 0 Pass 0.0105 6160 0 0 Pass 0.0108 5781 0 0 Pass 0.0110 5431 0 0 Pass 0.0113 5106 0 0 Pass 0.0116 4808 0 0 Pass 0.0118 4532 0 0 Pass 0.0121 4256 0 0 Pass 0.0124 4017 0 0 Pass 0.0126 3792 0 0 Pass 0.0129 3551 0 0 Pass 0.0132 3337 0 0 Pass 0.0134 3138 0 0 Pass 0.0137 2952 0 0 Pass 0.0139 2789 0 0 Pass 0.0142 2599 0 0 Pass 0.0145 2447 0 0 Pass 0.0147 2308 0 0 Pass 0.0150 2162 0 0 Pass 0.0153 2030 0 0 Pass 0.0155 1901 0 0 Pass 0.0158 1790 0 0 Pass 0.0161 1692 0 0 Pass 0.0163 1589 0 0 Pass 0.0166 1483 0 0 Pass 0.0169 1382 0 0 Pass 0.0171 1292 0 0 Pass 0.0174 1222 0 0 Pass 0.0177 1155 0 0 Pass 0.0179 1098 0 0 Pass 0.0182 1049 0 0 Pass 0.0185 997 0 0 Pass 0.0187 930 0 0 Pass 0.0190 884 0 0 Pass 0.0193 837 0 0 Pass 0.0195 789 0 0 Pass 0.0198 743 0 0 Pass 0.0201 713 0 0 Pass 0.0203 670 0 0 Pass 0.0206 631 0 0 Pass 18557 - Infiltration West SSD 10/25/2017 11:06:00 AM Page 12 0.0209 596 0 0 Pass 0.0211 566 0 0 Pass 0.0214 539 0 0 Pass 0.0217 497 0 0 Pass 0.0219 473 0 0 Pass 0.0222 436 0 0 Pass 0.0225 401 0 0 Pass 0.0227 366 0 0 Pass 0.0230 348 0 0 Pass 0.0233 323 0 0 Pass 0.0235 296 0 0 Pass 0.0238 273 0 0 Pass 0.0241 256 0 0 Pass 0.0243 235 0 0 Pass 0.0246 217 0 0 Pass 0.0249 195 0 0 Pass 0.0251 180 0 0 Pass 0.0254 158 0 0 Pass 0.0257 145 0 0 Pass 0.0259 129 0 0 Pass 0.0262 119 0 0 Pass 0.0265 109 0 0 Pass 0.0267 97 0 0 Pass 0.0270 91 0 0 Pass 0.0273 82 0 0 Pass 0.0275 76 0 0 Pass 0.0278 69 0 0 Pass 0.0281 61 0 0 Pass 0.0283 54 0 0 Pass 0.0286 48 0 0 Pass 0.0289 41 0 0 Pass 0.0291 38 0 0 Pass 0.0294 33 0 0 Pass 0.0297 27 0 0 Pass 0.0299 22 0 0 Pass 0.0302 21 0 0 Pass 0.0305 20 0 0 Pass 0.0307 19 0 0 Pass 0.0310 17 0 0 Pass 0.0312 14 0 0 Pass 0.0315 12 0 0 Pass 0.0318 8 0 0 Pass 0.0320 4 0 0 Pass 0.0323 3 0 0 Pass 0.0326 3 0 0 Pass 0.0328 3 0 0 Pass 0.0331 3 0 0 Pass 18557 - Infiltration West SSD 10/25/2017 11:06:19 AM Page 17 Appendix Predeveloped Schematic Mitigated Schematic EASTERN PERMEABLE PAVEMENT CALCULATIONS WWHM2012 PROJECT REPORT 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 2 General Model Information Project Name:18557 - Infiltration East SSD Site Name:OB Renton Site Address:800 SW 16th St. City:Renton Report Date:10/25/2017 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2017/04/14 Version:4.2.13 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 0.46 Pervious Total 0.46 Impervious Land Use acre Impervious Total 0 Basin Total 0.46 Element Flows To: Surface Interflow Groundwater 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.02 Pervious Total 0.02 Impervious Land Use acre PARKING FLAT 0.1 Impervious Total 0.1 Basin Total 0.12 Element Flows To: Surface Interflow Groundwater SSD Table 2 SSD Table 2 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 5 Basin 2 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.02 Pervious Total 0.02 Impervious Land Use acre PARKING FLAT 0.1 Impervious Total 0.1 Basin Total 0.12 Element Flows To: Surface Interflow Groundwater SSD Table 2 SSD Table 2 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 7 Mitigated Routing SSD Table 2 Depth:1 ft. Element Flows To: Outlet 1 Outlet 2 SSD Table Hydraulic Table Stage Area Volume Infilt (feet) (ac.) (ac-ft.) Manual (cfs) NotUsed NotUsed NotUsed 0.100 0.110 0.003 0.000 0.055 0.000 0.000 0.000 0.200 0.110 0.007 0.000 0.055 0.000 0.000 0.000 0.300 0.110 0.010 0.000 0.055 0.000 0.000 0.000 0.400 0.110 0.013 0.000 0.055 0.000 0.000 0.000 0.500 0.110 0.017 0.000 0.055 0.000 0.000 0.000 0.600 0.110 0.020 0.000 0.055 0.000 0.000 0.000 0.700 0.110 0.023 0.000 0.055 0.000 0.000 0.000 0.800 0.110 0.026 0.000 0.055 0.000 0.000 0.000 0.900 0.110 0.030 0.000 0.055 0.000 0.000 0.000 1.000 0.110 0.033 0.000 0.055 0.000 0.000 0.000 Note: Precipitation is applied to the 0.11 acre area of pervious pavement. 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 8 SSD Table 2 Depth:1 ft. Element Flows To: Outlet 1 Outlet 2 SSD Table Hydraulic Table Stage Area Volume Infilt (feet) (ac.) (ac-ft.) Manual (cfs) NotUsed NotUsed NotUsed 0.100 0.110 0.003 0.000 0.055 0.000 0.000 0.000 0.200 0.110 0.007 0.000 0.055 0.000 0.000 0.000 0.300 0.110 0.010 0.000 0.055 0.000 0.000 0.000 0.400 0.110 0.013 0.000 0.055 0.000 0.000 0.000 0.500 0.110 0.017 0.000 0.055 0.000 0.000 0.000 0.600 0.110 0.020 0.000 0.055 0.000 0.000 0.000 0.700 0.110 0.023 0.000 0.055 0.000 0.000 0.000 0.800 0.110 0.026 0.000 0.055 0.000 0.000 0.000 0.900 0.110 0.030 0.000 0.055 0.000 0.000 0.000 1.000 0.110 0.033 0.000 0.055 0.000 0.000 0.000 Note: Precipitation is applied to the 0.11 acre area of pervious pavement. 18557 - Infiltration East SSD 10/25/2017 10:50:18 AM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.46 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.04 Total Impervious Area:0.2 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.013524 5 year 0.021241 10 year 0.025613 25 year 0.030246 50 year 0.033113 100 year 0.035551 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.013 0.000 1950 0.017 0.000 1951 0.030 0.000 1952 0.009 0.000 1953 0.008 0.000 1954 0.012 0.000 1955 0.019 0.000 1956 0.015 0.000 1957 0.012 0.000 1958 0.013 0.000 18557 - Infiltration East SSD 10/25/2017 10:50:50 AM Page 10 1959 0.012 0.000 1960 0.020 0.000 1961 0.011 0.000 1962 0.007 0.000 1963 0.010 0.000 1964 0.013 0.000 1965 0.009 0.000 1966 0.009 0.000 1967 0.018 0.000 1968 0.011 0.000 1969 0.011 0.000 1970 0.009 0.000 1971 0.010 0.000 1972 0.022 0.000 1973 0.010 0.000 1974 0.011 0.000 1975 0.015 0.000 1976 0.011 0.000 1977 0.001 0.000 1978 0.009 0.000 1979 0.006 0.000 1980 0.021 0.000 1981 0.008 0.000 1982 0.016 0.000 1983 0.014 0.000 1984 0.009 0.000 1985 0.005 0.000 1986 0.023 0.000 1987 0.021 0.000 1988 0.008 0.000 1989 0.005 0.000 1990 0.043 0.000 1991 0.026 0.000 1992 0.010 0.000 1993 0.010 0.000 1994 0.004 0.000 1995 0.015 0.000 1996 0.032 0.000 1997 0.026 0.000 1998 0.006 0.000 1999 0.025 0.000 2000 0.010 0.000 2001 0.002 0.000 2002 0.011 0.000 2003 0.015 0.000 2004 0.019 0.000 2005 0.014 0.000 2006 0.016 0.000 2007 0.032 0.000 2008 0.042 0.000 2009 0.020 0.000 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0434 0.0000 2 0.0415 0.0000 3 0.0322 0.0000 18557 - Infiltration East SSD 10/25/2017 10:50:50 AM Page 11 4 0.0317 0.0000 5 0.0298 0.0000 6 0.0265 0.0000 7 0.0261 0.0000 8 0.0248 0.0000 9 0.0234 0.0000 10 0.0222 0.0000 11 0.0210 0.0000 12 0.0207 0.0000 13 0.0204 0.0000 14 0.0201 0.0000 15 0.0189 0.0000 16 0.0186 0.0000 17 0.0184 0.0000 18 0.0166 0.0000 19 0.0162 0.0000 20 0.0160 0.0000 21 0.0150 0.0000 22 0.0148 0.0000 23 0.0148 0.0000 24 0.0146 0.0000 25 0.0145 0.0000 26 0.0136 0.0000 27 0.0134 0.0000 28 0.0133 0.0000 29 0.0128 0.0000 30 0.0119 0.0000 31 0.0117 0.0000 32 0.0115 0.0000 33 0.0115 0.0000 34 0.0115 0.0000 35 0.0114 0.0000 36 0.0112 0.0000 37 0.0109 0.0000 38 0.0107 0.0000 39 0.0105 0.0000 40 0.0105 0.0000 41 0.0101 0.0000 42 0.0101 0.0000 43 0.0099 0.0000 44 0.0097 0.0000 45 0.0094 0.0000 46 0.0094 0.0000 47 0.0093 0.0000 48 0.0091 0.0000 49 0.0089 0.0000 50 0.0088 0.0000 51 0.0084 0.0000 52 0.0082 0.0000 53 0.0076 0.0000 54 0.0071 0.0000 55 0.0060 0.0000 56 0.0057 0.0000 57 0.0053 0.0000 58 0.0053 0.0000 59 0.0035 0.0000 60 0.0019 0.0000 61 0.0013 0.0000 18557 - Infiltration East SSD 10/25/2017 10:50:50 AM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0068 17547 0 0 Pass 0.0070 16164 0 0 Pass 0.0073 14964 0 0 Pass 0.0076 13851 0 0 Pass 0.0078 12814 0 0 Pass 0.0081 11811 0 0 Pass 0.0084 10898 0 0 Pass 0.0086 10119 0 0 Pass 0.0089 9383 0 0 Pass 0.0092 8731 0 0 Pass 0.0094 8145 0 0 Pass 0.0097 7593 0 0 Pass 0.0100 7058 0 0 Pass 0.0102 6590 0 0 Pass 0.0105 6160 0 0 Pass 0.0108 5781 0 0 Pass 0.0110 5431 0 0 Pass 0.0113 5106 0 0 Pass 0.0116 4808 0 0 Pass 0.0118 4532 0 0 Pass 0.0121 4256 0 0 Pass 0.0124 4017 0 0 Pass 0.0126 3792 0 0 Pass 0.0129 3551 0 0 Pass 0.0132 3337 0 0 Pass 0.0134 3138 0 0 Pass 0.0137 2952 0 0 Pass 0.0139 2789 0 0 Pass 0.0142 2599 0 0 Pass 0.0145 2447 0 0 Pass 0.0147 2308 0 0 Pass 0.0150 2162 0 0 Pass 0.0153 2030 0 0 Pass 0.0155 1901 0 0 Pass 0.0158 1790 0 0 Pass 0.0161 1692 0 0 Pass 0.0163 1589 0 0 Pass 0.0166 1483 0 0 Pass 0.0169 1382 0 0 Pass 0.0171 1292 0 0 Pass 0.0174 1222 0 0 Pass 0.0177 1155 0 0 Pass 0.0179 1098 0 0 Pass 0.0182 1049 0 0 Pass 0.0185 997 0 0 Pass 0.0187 930 0 0 Pass 0.0190 884 0 0 Pass 0.0193 837 0 0 Pass 0.0195 789 0 0 Pass 0.0198 743 0 0 Pass 0.0201 713 0 0 Pass 0.0203 670 0 0 Pass 0.0206 631 0 0 Pass 18557 - Infiltration East SSD 10/25/2017 10:50:50 AM Page 14 0.0209 596 0 0 Pass 0.0211 566 0 0 Pass 0.0214 539 0 0 Pass 0.0217 497 0 0 Pass 0.0219 473 0 0 Pass 0.0222 436 0 0 Pass 0.0225 401 0 0 Pass 0.0227 366 0 0 Pass 0.0230 348 0 0 Pass 0.0233 323 0 0 Pass 0.0235 296 0 0 Pass 0.0238 273 0 0 Pass 0.0241 256 0 0 Pass 0.0243 235 0 0 Pass 0.0246 217 0 0 Pass 0.0249 195 0 0 Pass 0.0251 180 0 0 Pass 0.0254 158 0 0 Pass 0.0257 145 0 0 Pass 0.0259 129 0 0 Pass 0.0262 119 0 0 Pass 0.0265 109 0 0 Pass 0.0267 97 0 0 Pass 0.0270 91 0 0 Pass 0.0273 82 0 0 Pass 0.0275 76 0 0 Pass 0.0278 69 0 0 Pass 0.0281 61 0 0 Pass 0.0283 54 0 0 Pass 0.0286 48 0 0 Pass 0.0289 41 0 0 Pass 0.0291 38 0 0 Pass 0.0294 33 0 0 Pass 0.0297 27 0 0 Pass 0.0299 22 0 0 Pass 0.0302 21 0 0 Pass 0.0305 20 0 0 Pass 0.0307 19 0 0 Pass 0.0310 17 0 0 Pass 0.0312 14 0 0 Pass 0.0315 12 0 0 Pass 0.0318 8 0 0 Pass 0.0320 4 0 0 Pass 0.0323 3 0 0 Pass 0.0326 3 0 0 Pass 0.0328 3 0 0 Pass 0.0331 3 0 0 Pass 18557 - Infiltration East SSD 10/25/2017 10:51:10 AM Page 19 Appendix Predeveloped Schematic Mitigated Schematic Tab 5.0 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN Since the site is less than 10 acres in size, the rational method can be appropriately used to predict peak runoff volumes. The only conveyance element within the project limits func tions as an emergency overflow for 0.5 acres of parking area adjacent to the proposed improvements. The peak runoff from the 100-year precipitation event, along with Manning's equation, was used to determine the appropriate pipe size for the overflow conveyance elements. See the following worksheet for specifics. Rational Method WorksheetJOB NAME:C= 0.9 n= 0.012JOB#: 18557d= 12 Tc= 6.3FILE NO.:A= Contributing Area (Ac) Qd= Design Flow (cfs)C= Runoff Coefficient Qf= Full Capacity Flow (cfs)STORMAr BrPRECIP=3.95Tc= Time of Concentration (min) Vd= Velocity at Design Flow (fps) 2YR 1.58 0.58Ar=2.61I= Intensity at Tc (in/hr) Vf= Velocity at Full Flow (fps) 10YR 2.44 0.64Br=0.63d= Diameter of Pipe (in) s= Slope of pipe (%) 25YR 2.66 0.65L= Length of Pipe (ft) n= Manning Roughness Coefficient 50YR 2.75 0.65D= Water Depth at Qd (in) Tt= Travel Time at Vd (min) 100YR 2.61 0.63FROM TO A s L d Tc n C SUM A A*C SUM A*C I Qd QfQd/QfD/d D Vf Vd====== ====== ====== ====== ================== ====== ====== ====== ===================== ====== ====== ====== ====== ====== ====== ======CB#3 EX. CB 0.50 1.30 120 86.3 0.012 0.9 0.5 0.45 0.45 3.23 1.46 1.490.9750.795 6.36 4.28 4.83Total Site Area0.50COEFFICIENTS FOR THE RATIONAL METHOD "Ir"-EQUATIONBARGHAUSEN CONSULTING ENGINEERS - PIPE FLOW CALCULATOR using the Rational Method & Mannings Equation for 100 year storm eventOB RENTON Tab 6.0 6.0 SPECIAL REPORTS AND STUDIES 6.0 SPECIAL REPORTS AND STUDIES The following special reports and studies are included: 6.1 Geotechnical Engineering Evaluation Tab 7.0 7.0 OTHER PERMITS 7.0 OTHER PERMITS Construction Stormwater General Permit (Department of Ecology) Tab 8.0 8.0 CSWPP ANALYSIS AND DESIGN 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENT (CSWPP) ANALYSIS AND DESIGN A. Erosion and Sediment Control (ESC) Plan Analysis and Design Will be provided with the final Technical Information Report. B. Stormwater Pollution Prevention and Spill (SWPPS) Plan Design Will be provided with the final Technical Information Report. Tab 9.0 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATIONS OF COVENANT 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Will be provided with the final Technical Information Report if requested by the City of Renton. Tab 10.0 10.0 OPERATIONS AND MAINTENANCE MANUAL 10.0 OPERATIONS AND MAINTENANCE MANUAL APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Site 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. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment 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 dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity 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. 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. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged (If Applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-3 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 2 – INFILTRATION FACILITIES Maintenance Component Defect or Problem Conditions When Maintenance Is Needed Results Expected When Maintenance Is Performed Inlet/Outlet Pipes 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. 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. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. 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. 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. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond 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 at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-4 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure 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 and debris 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. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab 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. 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 in walls or bottom 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 is structurally sound. 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. 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. Inlet/Outlet Pipe 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. 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. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Metal Grates (Catch Basins) 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 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. Manhole Cover/Lid 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. 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. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes 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. 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. Ditches 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. 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. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-11