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HomeMy WebLinkAboutR_TIR_Matveyev_Short_Plat_190710.pdf Western Washington Division Eastern Washington Division 165 NE Juniper St., Ste 201, Issaquah, WA 98027 108 East 2nd Street, Cle Elum, WA 98922 Phone: (425) 392-0250 Fax: (425) 391-3055 Phone: (509) 674-7433 Fax: (509) 674-7419 www.EncompassES.net TECHNICAL INFORMATION REPORT For Matveyev Short Plat 1810 Park Avenue North Renton, WA 98056 January 10, 2018 Revised: May 16, 2019 Prepared by: Samuel Salo Encompass Engineering Job No. 16645 Prepared For: Emil Matveyev 807 Kirkland Way Kirkland, WA 98033 5/15/15/15/16666/19/19/19/19 SURFACE WATER UTILITY jfarah 07/10/2019 DEVELOPMENT ENGINEERING swarlick 07/24/2019 Matveyev Short Plat Technical Information Report 5/16/19 P a g e i Table of Contents I. PROJECT OVERVIEW ................................................................................................................ 1 II. CONDITIONS AND REQUIREMENTS SUMMARY ...................................................................... 3 III. OFF-SITE ANALYSIS .................................................................................................................. 5 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ........................... 12 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ..................................................................... 14 VI. SPECIAL REPORTS AND STUDIES ............................................................................................ 15 VII. OTHER PERMITS ..................................................................................................................... 15 VIII. CSWPPP ANALYSIS AND DESIGN............................................................................................ 15 IX. BOND QUANTITIES and DECLARATION of COVENANT .......................................................... 17 X. OPERATION AND MAINTENANCE MANUAL .......................................................................... 17 Appendix A Geotechnical Engineering Study by Earth Solutions NW LLC dated May 18, 2017 Appendix B Bond Quantity Worksheet Appendix C Operations and Maintenance Appendix D Complete WWHM2012 Output Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 I. PROJECT OVERVIEW Site Address: 3810 Park Avenue North, Renton WA, 98056 (see Vicinity Map) King County Tax Parcel: 334270-0510 Vicinity Map This project proposes to subdivide this 0.48-acre parcel into two single-family residential lots and a shared driveway tract. This site is within the Residential-6 (R-6) Zone. One single-family residence is presently on the property and will be removed prior to construction. One new lot (Lot 2), east of the existing residence, is proposed for a new single-family home. The proposed lot sizes are 7,947 SF for Lot 1 and 10,047 SF for Lot 2. There is also a 2,401 SF Tract proposed to provide access to the proposed lots. The site generally slopes to the north and northwest at 8 percent. Moderate landslide hazards and sensitive slopes are mapped within 50 feet of the project site. The soil of the site is mapped as silty sand and sandy silt per the Geotechnical Engineering Study by Earth Solutions NW, LLC (see appendix A) and Indianola loamy sand per the web soils survey (see map on next page). Pre-developed Site Conditions: The project site presently consists of a single-family residence with a detached garage and a paved driveway that provides access to Park Avenue N. Except for the structures and driveway, the site is vegetated with grass areas and shrubs. Matveyev Short Plat Technical Information Report 5/16/19 P a g e 2 Post-developed Site Conditions: This proposal incorporates the construction of on-site and off-site infrastructure to support the future construction of 2 new single-family detached residences. All existing structures will be demolished prior to the start of construction. The lots will be accessed via one driveway within Tract A that connects to Park Avenue N. Developed rooftop runoff will be routed to on-site dispersion trenches. Storm water quality is not required since the new pollution generating impervious surface is less than 5,000 SF. The pervious landscape areas will be allowed to infiltrate naturally into the native soil. The project abuts Park Avenue N to the East. The proposed off-site frontage improvements along Park Avenue N include the installation of 6’ parking lane, curb, gutter, 8’ landscape strip and a 5’ sidewalk within the 16’ ROW dedication and additional 6.5’ ROW dedication. Soils Map Proposed Drainage Controls A 15’ dispersion trench will be installed on lot two with a 25’ vegetated flowpath segment. This allows up to 1,050 SF of impervious area to be mitigated on Lot 2. Due to the site topography we are not able to provide flow control BMPs for Lot 1, Tract A or the frontage improvements. Dispersion is not feasible as these areas downstream of our project site. Infiltration BMPs are infeasible due to poorly infiltrating soils per the Geotechnical Engineering Study. This project also proposes to use reduced impervious surface credits per Section C.2.9 of the 2017 City of Renton Surface Water Design Manual to meet minimum stormwater mitigation requirements. (See Section IV for additional information on BMPs and Appendix A for more soils information). SITE Matveyev Short Plat Technical Information Report 5/16/19 P a g e 3 II. CONDITIONS AND REQUIREMENTS SUMMARY CORE REQUIREMENTS Core Requirement #1: Discharge at the Natural Location Runoff from the eastern portion of the site generally sheet flows to the northern edge of the property. Runoff from the western portion of the site sheet flows to the northwest edge of the site. This drainage pattern will be maintained as the site is developed. Core Requirement #2: Offsite Analysis An offsite drainage analysis is provided in Section III of this TIR. Level 1 Drainage Analysis has been performed and no problems downstream have been identified. Core Requirement #3: Flow Control Facilities This project lies within the Peak Rate flow control applications area, therefore predeveloped conditions may be modeled as existing. Flow control facilities are not required since the project does not generate 0.15-cfs increase in the existing site conditions 100-year peak flow using 15-minute timesteps per the 2017 City of Renton Surface Water Design Manual. Basic flow control BMPs will be utilized for the proposed lots. Core Requirement #4: Conveyance System Conveyance system analysis is not warranted for this project. Core Requirement #5: Erosion & Sediment Control A temporary erosion and sediment control (TESC) plan is included with this submittal. See Section VIII of this TIR for a list of BMPs to be utilized. Core Requirement #6: Maintenance & Operations An Operation and Maintenance Manual is provided in Appendix C. Core Requirement #7: Financial Guarantees & Liability The owner will arrange for any financial guarantees and liabilities required by the permit. Matveyev Short Plat Technical Information Report 5/16/19 P a g e 4 Core Requirement #8: Water Quality Facilities A tract of 1,600 sf and a driveway area of 1,543 SF for the lots have been proposed. This gives us 3,143 SF of PGIS. This is less than 5,000 SF threshold, therefore the project is exempt from the water quality requirement. Core Requirement #9: On-Site BMP’s A 15’ dispersion trench will be installed on lot two with a 25’ vegetated flowpath segment. This allows up to 1,050 SF of impervious area to be mitigated on Lot 2. Due to the site topography we are not able to provide flow control BMPs for Lot 1, Tract A or the frontage improvements. Dispersion is not feasible as these areas downstream of our project site. Infiltration BMPs are infeasible due to poorly infiltrating soils per the Geotechnical Engineering Study. This project also proposes to use reduced impervious surface credits per Section C.2.9 of the 2017 City of Renton Surface Water Design Manual to meet minimum stormwater mitigation requirements. (See Section IV for additional information on BMPs and Appendix A for more soils information). SPECIAL REQUIREMENTS: Special Requirement #1: Other Adopted Area-Specific Requirements This site does not fall under any other adopted area-specific requirements per the city of Renton surface water design manual. Page 1 – 89, Section 1.3.1 Critical Drainage Area – N/A Master Drainage Plan – N/A Basin Plan – N/A Lake Management Plan –N/A Shared Facility Drainage Plan – N/A Special Requirement #2: Flood Hazard Area Delineation This site does not fall under the flood hazard area delineation requirements per the Renton Surface Water Design Manual. Page - 1-90, Section 1.3.2 Special Requirement #3: Flood Protection Facilities This site does not fall under the flood protection facilities requirements per the Renton Surface Water Design Manual. Page – 1-91, Section 1.3.3 Matveyev Short Plat Technical Information Report 5/16/19 P a g e 5 Special Requirement #4: Source control This site does not fall under the source control requirements per the Renton Surface Water Design Manual. Page – 1-92, Section 1.3.4 Special Requirement #5: Oil Control This site does not fall under the oil control requirements per the Renton Surface Water Design Manual. Page – 1-94, Section 1.3.5 Special Requirement #6: Aquifer Protection Areas This site does not fall under the aquifer protection areas requirement per the Renton Surface Water Design Manual. Page – 1-97, Section 1.3.6 III. OFF-SITE ANALYSIS The level 1 analysis was done Thursday June 1, 2017 around 9:00AM. The weather was cloudy with some rain, roughly 59°. The site is currently developed with a single-family residence, detached garage and driveway access. The site is comprised of tall grasses with trees and shrubs throughout. There are two flow patterns for the site. The eastern portion of the sight slopes to the north. The western portion slopes to the west and northwest. Runoff from the eastern portion of the site generally sheet flows to the northern edge of the property. It then flows through the adjacent properties and onto N 39th Pl. where it is collected by private detention tanks by inlets in the street. The tanks drain through 12” concrete pipe into the Park Ave N drainage system. This is where it converges with the runoff from the western portion of the site. Runoff from the western portion of the site generally sheet flows towards the northeast corner of the property with some concentrated flow on the driveway. Runoff is then collected in 24” drainage ditch to a 12” concrete culvert passing under the driveway. After traveling 26’ through another drainage ditch of similar size runoff is then fed into a 12” concrete pipe entering the Park Avenue drainage system. This is where it converges with the runoff from the eastern portion of the site. It then flows north to N 40th Street N through a series of 12” concrete and ductile iron pipe. Runoff then travels west along N 40th Street N and under Lake Washington Blvd through 18” corrugated plastic pipe, then under the Burlington Northern Inc. Railroad through 24” corrugated plastic pipe. Here the runoff travels through a 2’ wide 27’ long drainage channel before entering a 24” corrugated plastic pipe leading under Wells Ave N. This is where the level 1 analysis was completed. Using the city of Renton CORMaps we see that the runoff then travels through another series of pipes before being discharged into Lake Washington. (See Downstream Map) Matveyev Short Plat Technical Information Report 5/16/19 P a g e 6 Downstream Map Photo 1 – Existing Conditions and Development SITE Conversion Point Matveyev Short Plat Technical Information Report 5/16/19 P a g e 7 Photo 2 – Drainage Ditch South of Driveway on Park Avenue Photo 3 – Drainage Ditch North of Driveway on Park Avenue Matveyev Short Plat Technical Information Report 5/16/19 P a g e 8 Photo 4 – Transition to 12” Ductile Iron Pipe Photo 5 – Drainage Channel from Burlington Northern Railroad Matveyev Short Plat Technical Information Report 5/16/19 P a g e 9 Map of Photo Locations Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 2 IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Flow Control BMPs Based on the geotechnical report and addendum, infiltration is not feasible for the site due to the soil types. It is required that 10% of the lot area be mitigated for flow control. Lot 1 is 7,947 SF therefore we need flow control for 10% or 795 SF. Lot 2 is 10,047 SF therefore we need flow control for 10% or 1,005 SF. It was decided that 10’ trench with a 25’ flow vegetated flow path segment would be installed on Lot 2. This will mitigate 700 SF of impervious surface from the lot. The remaining area to be mitigated is 305 SF. Due to site area we cannot lengthen the trench to disperse more area. The soils on-site cannot infiltrate therefore permeable pavement, limited or full infiltration and bioretention are not feasible. This project also proposes to use reduced impervious surface credits per Section C.2.9 of the 2017 City of Renton Surface Water Design Manual. The maximum allowable impervious surface for Lot 1 is 3,205 SF (4,000 SF – 795 SF). The maximum allowable impervious surface for Lot 2 is 3,695 (4,000 SF – 305 SF). No other BMPs are feasible for the project site, therefore this design mitigates stormwater runoff to the maximum extent feasible. Flow Control The site is exempt from providing flow control as the difference in 100-Year Peaks is 0.2568- 0.2348 = 0.022 which is less than 0.15 CFS. This site also falls under the Peak Rate flow control applications area, therefore predeveloped conditions can be modeled as existing (see area calculations and WWHM analysis on next page). Area Calculations: Area Breakdown: Site Area – 20,395 SF or 0.47 Acre Impervious Area Calculation for WWHM: · The proposed improvements include dividing the parcel into two separate lots. Lot 1 will be 7,947 sf and Lot 2 will be 10,047 SF. There will also be a tract of land (Tract A) that is 2,401 SF and an offsite area of 1,625 SF. The existing impervious area is 4,115 SF. The proposed impervious area is 7,906 SF. The offsite area was not included in the model due to the increase in 100- year flows of 0.022 CFS. Adding in the offsite area will not push this over the 0.15 CFS threshold. Tract A: 1,600 SF Lot 1: Maximum Impervious = 3,205 SF Lot 2: Maximum Impervious = 3,695 SF TOTAL IMPERVIOUS: 8,500 SF (0.19 AC) Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 3 WWHM Analysis Soil Type: Existing and Developed– Indianola Loamy Sand Existing Conditions: Developed Conditions: Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 4 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN A conveyance system analysis was performed using King County iMap and WWHM2012. iMap was used to first estimate the area tributary to our proposed storm drainage system. This was found to be approximately 8.19 Acres. This area appeared to be approximately 45% impervious. This area was then modeled in WWHM resulting in a 25-year return flow rate of 3.16 CFS. A 12” CPP at 0.5% is capable of conveying 3.2 CFS, therefore our system is capable of conveying the upstream tributary area. See map and detailed description of calculation on following page. Map of Upstream Tributary Area Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 5 Map of Pipes The conveyance calculations were performed using Manning’s Equation. The conveyance system was checked to ensure that during the 25-year storm event, the system would function adequately. The 100-year peak flow from the developed site using WWHM2012 with 15 minute time steps was compared to the maximum capacity of the pipe. Using the Manning’s Equation, the maximum capacity of a 6”, 8” and 12” pipe for reference was calculated: Pipe Diameter (inches) Pipe Slope Capacity (CFS) 6 1.0% 0.65 8 0.50% 1.34 12 0.50% 3.20 As shown in the table the capacity of the 12” pipe is greater than the 3.16 CFS required to convey the upstream tributary area. VI. SPECIAL REPORTS AND STUDIES Geotechnical Engineering Study by Earth Solutions NW LLC Dated May 18, 2017 Arborist Report by American Forest Management Dated March 9th 2017 VII. OTHER PERMITS Building permits will be required. VIII. CSWPPP ANALYSIS AND DESIGN The potential for erosion within the site will be mitigated by use of erosion control measures during clearing, grading, and site development activities. Filter fences will be installed along the downhill perimeter of the site to protect adjacent properties from sediment-laden water. The existing access will be installed at the entrance to the site to protect mud from entering the paved roadway. Stockpiles and exposed disturbed areas will be covered to protect from erosion and sediment runoff. Element 1: Mark Clearing Limits. All clearing and grading will be clearly marked in the field prior to construction in accordance to the plans and specifications. Prior to beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. These will be clearly marked, both in the field and on the plans, to prevent damage and offsite impacts. Plastic, metal, or stake wire fence may be used to mark the clearing limits. Element 2: Establish Construction Access. The existing access from Park Avenue N will be utilized as the construction access. Access points will be stabilized with a pad of quarry spalls, crushed rock, or equivalent BMP prior to traffic leaving the construction site to minimize the tracking of sediment onto all roads and accesses. Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 6 Element 3: Control Flow Rates. No flow rate control is proposed at this time. Element 4: Install Sediment Controls. Soils should be covered if not worked for 7 days during the dry season or 2 days during the wet season. The street should be swept each night or as required. If the minimum BMPs fail to retain sediment to the sight, additional BMPs will be used. Element 5: Stabilize Soils. Soils will be covered if not worked for 7 days during the dry season or 2 days during the wet season. Soil stockpiles will be covered unless worked. Soil stockpiles will be located away from drain inlets and surface water discharge locations. Soil stockpiles will be stabilized and covered as needed. Soils will be stabilized at the end of the shift before holidays or weekends if needed based on weather forecast. Element 6: Protect Slopes. Slope protection is not proposed as there are no slopes on the site. Element 7: Protect Drain Inlets. Existing drain inlets will be protected during construction Element 8: Stabilize Channels and Outlets. Existing and proposed drainage outlets will be stabilized throughout construction. Element 9: Control Pollutants. Pollution generated from construction must be controlled at all times. Control of pollutants other than sediments includes the following:  All pollutants other than sediments will be handled and disposed of in a manner that does not cause contamination of stormwater.  Cover, containment and protection from vandalism will be provided for all chemicals, liquid products, petroleum products, and non-inert wastes present on the project site.  Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces will be cleaned immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. Element 10: Control De-Watering. De-watering is not anticipated for the site. In the event that dewatering is necessary, the waste water will be treated such that sediment remains on site. This will be done by routing the storm water through a straw filter or sediment trap. Element 11: Maintain BMPs. BMPs will be inspected monthly and after every significant storm event, Sediment will be removed from the BMPs as necessary for them to continue operating at the required performance level. In the event that a BMPs has been damaged, it will be replaced immediately. Matveyev Short Plat Technical Information Report 5/16/19 P a g e 1 7 Element 12: Manage the Project. Construction activities will be phased such that the impact to the area will be kept at a minimum. Coordination will occur with all utility agencies that are affected by this project. BMPs will be inspected regularly and after each significant storm event. The Contractor will provide a Certified Erosion and Sediment Control Specialist. If for any reason a BMPs is not sufficient for the project, additional BMPs will be installed. IX. BOND QUANTITIES and DECLARATION of COVENANT Bond Quantities The bond quantity is included in Appendix B of this TIR. Facility Summaries Not applicable. Declaration of Covenant The Declaration of Covenant will have to be approved and recorded. X. OPERATION AND MAINTENANCE MANUAL Operation and maintenance of the site and all proposed stormwater facilities on this project will be required after the construction completion and throughout the life of this development. This development is served by a series of storm drain pipes that collect and convey post development runoff associated with this project, catch basins, infiltration drywells, and infiltration trenches. Each storm drainage component mentioned above consists of several items that need to be properly maintained. The list below specifies the maintenance requirements for each component of the stormwater facility being constructed. Applicable maintenance requirements, taken from City of Renton Stormwater Design Manual, are included in Appendix C. Proposed maintenance requirements include: 1. Dispersion Trench 2. Catch Basins and Manholes 3. Conveyance Pipes and Ditches Matveyev Short Plat Technical Information Report Appendix A Geotechnical Report EarthSolutionsNWLLC EarthSolutions NW LLC Geotechnical Engineering Geology Environmental Scientists Construction Monitoring 1805 -136th Place N.E.,Suite 201 Bellevue,WA 98005 (425)449-4704 Fax (425)449-4711 www.earthsolutionsnw.com GEOTECHNICAL ENGINEERING STUDY PROPOSED SHORT PLAT 3810 PARK AVENUE NORTH RENTON,WASHINGTON ES-5134 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring EarthSolutionsNWLLC EarthSolutions NW LLC and Environmental Sciences Vicinity Map Matveyev Short Plat Renton,Washington MRS CGH 04/28/2017 April 2017 5134 1 NORTH NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. Reference: King County,Washington Map 626 By The Thomas Guide Rand McNally 32nd Edition SITE Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring EarthSolutionsNWLLC EarthSolutions NW LLC and Environmental Sciences NORTH 0 2 0 4 0 8 0 Sc ale in Feet1"=4 0 ' NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. NOTE:The graphics shown on this plate are not intended for design purposes or precise scale measurements,but only to illustrate the approximate test locations relative to the approximate locations of existing and /or proposed site features.The information illustrated is largely based on data provided by the client at the time of our study.ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. LEGEND Approximate Location of ESNW Test Pit,Proj.No. ES-5134,Mar.2017 Subject Site Existing Building Test Pit Location Plan Matveyev Short Plat Renton,Washington MRS CGH 05/01/2017 May 2017 5134 2 TP-1 TP-2 TP-4 TP-3 House Garage Shed Landscaping Pond TP-1 Asphalt Driveway PARK AVENUE N.130 140 130 140 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring and Environmental Sciences EarthSolutionsNWLLC EarthSolutions NW LLC RETAINING WALL DRAINAGE DETAIL Matveyev Short Plat Renton,Washington MRS CGH 05/01/2017 May 2017 5134 3 NOTES: Free Draining Backfill should consist of soil having less than 5 percent fines. Percent passing #4 should be 25 to 75 percent. Sheet Drain may be feasible in lieu of Free Draining Backfill,per ESNW recommendations. Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1" Drain Rock. LEGEND: Free Draining Structural Backfill 1 inch Drain Rock 18"Min. Structural Fill Perforated Drain Pipe (Surround In Drain Rock) SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring and Environmental Sciences EarthSolutionsNWLLC EarthSolutions NW LLC FOOTING DRAIN DETAIL Slope Perforated Rigid Drain Pipe (Surround with 1"Rock) 18"(Min.) NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12"of less permeable,suitable soil.Slope away from building. LEGEND: Surface Seal;native soil or other low permeability material. 1"Drain Rock SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAW ING Matveyev Short Plat Renton,Washington MRS CGH 05/01/2017 May 2017 5134 4 Matveyev Short Plat Technical Information Report Appendix B Bond Quantity Worksheet CED Permit #:17-000389ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostDRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/DD-126.00$ SY* (CBs include frame and lid)BeehiveD-290.00$ EachThrough-curb Inlet FrameworkD-3400.00$ EachCB Type ID-41,500.00$ Each34,500.0023,000.00CB Type ILD-51,750.00$ EachCB Type II, 48" diameterD-62,300.00$ Each for additional depth over 4' D-7480.00$ FTCB Type II, 54" diameterD-82,500.00$ Each for additional depth over 4'D-9495.00$ FTCB Type II, 60" diameterD-102,800.00$ Each for additional depth over 4'D-11600.00$ FTCB Type II, 72" diameterD-126,000.00$ Each for additional depth over 4'D-13850.00$ FTCB Type II, 96" diameterD-1414,000.00$ Each for additional depth over 4'D-15925.00$ FTTrash Rack, 12"D-16350.00$ EachTrash Rack, 15"D-17410.00$ EachTrash Rack, 18"D-18480.00$ EachTrash Rack, 21"D-19550.00$ EachCleanout, PVC, 4"D-20150.00$ EachCleanout, PVC, 6"D-21170.00$ Each2340.00Cleanout, PVC, 8"D-22200.00$ EachCulvert, PVC, 4" D-2310.00$ LFCulvert, PVC, 6" D-2413.00$ LF1011,313.00Culvert, PVC, 8" D-2515.00$ LF18270.00Culvert, PVC, 12" D-2623.00$ LF1453,335.00Culvert, PVC, 15" D-2735.00$ LFCulvert, PVC, 18" D-2841.00$ LFCulvert, PVC, 24"D-2956.00$ LFCulvert, PVC, 30" D-3078.00$ LFCulvert, PVC, 36" D-31130.00$ LFCulvert, CMP, 8"D-3219.00$ LFCulvert, CMP, 12"D-3329.00$ LFSUBTOTAL THIS PAGE:7,835.003,000.001,923.00(B)(C)(D)(E)Quantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESPage 1 of 5Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 5/16/2019 CED Permit #:17-000389ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, CMP, 15"D-3435.00$ LFCulvert, CMP, 18"D-3541.00$ LFCulvert, CMP, 24"D-3656.00$ LFCulvert, CMP, 30"D-3778.00$ LFCulvert, CMP, 36"D-38130.00$ LFCulvert, CMP, 48"D-39190.00$ LFCulvert, CMP, 60"D-40270.00$ LFCulvert, CMP, 72"D-41350.00$ LFCulvert, Concrete, 8"D-4242.00$ LFCulvert, Concrete, 12"D-4348.00$ LFCulvert, Concrete, 15"D-4478.00$ LFCulvert, Concrete, 18"D-4548.00$ LFCulvert, Concrete, 24"D-4678.00$ LFCulvert, Concrete, 30"D-47125.00$ LFCulvert, Concrete, 36"D-48150.00$ LFCulvert, Concrete, 42"D-49175.00$ LFCulvert, Concrete, 48"D-50205.00$ LFCulvert, CPE Triple Wall, 6" D-5114.00$ LFCulvert, CPE Triple Wall, 8" D-5216.00$ LFCulvert, CPE Triple Wall, 12" D-5324.00$ LFCulvert, CPE Triple Wall, 15" D-5435.00$ LFCulvert, CPE Triple Wall, 18" D-5541.00$ LFCulvert, CPE Triple Wall, 24" D-5656.00$ LFCulvert, CPE Triple Wall, 30" D-5778.00$ LFCulvert, CPE Triple Wall, 36" D-58130.00$ LFCulvert, LCPE, 6"D-5960.00$ LFCulvert, LCPE, 8"D-6072.00$ LFCulvert, LCPE, 12"D-6184.00$ LFCulvert, LCPE, 15"D-6296.00$ LFCulvert, LCPE, 18"D-63108.00$ LFCulvert, LCPE, 24"D-64120.00$ LFCulvert, LCPE, 30"D-65132.00$ LFCulvert, LCPE, 36"D-66144.00$ LFCulvert, LCPE, 48"D-67156.00$ LFCulvert, LCPE, 54"D-68168.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 2 of 5Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 5/16/2019 CED Permit #:17-000389ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESDRAINAGE (Continued)Culvert, LCPE, 60"D-69180.00$ LFCulvert, LCPE, 72"D-70192.00$ LFCulvert, HDPE, 6"D-7142.00$ LFCulvert, HDPE, 8"D-7242.00$ LFCulvert, HDPE, 12"D-7374.00$ LFCulvert, HDPE, 15"D-74106.00$ LFCulvert, HDPE, 18"D-75138.00$ LFCulvert, HDPE, 24"D-76221.00$ LFCulvert, HDPE, 30"D-77276.00$ LFCulvert, HDPE, 36"D-78331.00$ LFCulvert, HDPE, 48"D-79386.00$ LFCulvert, HDPE, 54"D-80441.00$ LFCulvert, HDPE, 60"D-81496.00$ LFCulvert, HDPE, 72"D-82551.00$ LFPipe, Polypropylene, 6"D-8384.00$ LFPipe, Polypropylene, 8"D-8489.00$ LFPipe, Polypropylene, 12"D-8595.00$ LFPipe, Polypropylene, 15"D-86100.00$ LFPipe, Polypropylene, 18"D-87106.00$ LFPipe, Polypropylene, 24"D-88111.00$ LFPipe, Polypropylene, 30"D-89119.00$ LFPipe, Polypropylene, 36"D-90154.00$ LFPipe, Polypropylene, 48"D-91226.00$ LFPipe, Polypropylene, 54"D-92332.00$ LFPipe, Polypropylene, 60"D-93439.00$ LFPipe, Polypropylene, 72"D-94545.00$ LFCulvert, DI, 6"D-9561.00$ LFCulvert, DI, 8"D-9684.00$ LFCulvert, DI, 12"D-97106.00$ LFCulvert, DI, 15"D-98129.00$ LFCulvert, DI, 18"D-99152.00$ LFCulvert, DI, 24"D-100175.00$ LFCulvert, DI, 30"D-101198.00$ LFCulvert, DI, 36"D-102220.00$ LFCulvert, DI, 48"D-103243.00$ LFCulvert, DI, 54"D-104266.00$ LFCulvert, DI, 60"D-105289.00$ LFCulvert, DI, 72"D-106311.00$ LFSUBTOTAL THIS PAGE:(B)(C)(D)(E)Page 3 of 5Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 5/16/2019 CED Permit #:17-000389ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESSpecialty Drainage ItemsDitching SD-19.50$ CYFlow Dispersal Trench (1,436 base+)SD-328.00$ LF 1,436.00101,716.00 French Drain (3' depth)SD-426.00$ LFGeotextile, laid in trench, polypropyleneSD-53.00$ SYMid-tank Access Riser, 48" dia, 6' deepSD-62,000.00$ EachPond Overflow SpillwaySD-716.00$ SYRestrictor/Oil Separator, 12"SD-81,150.00$ EachRestrictor/Oil Separator, 15"SD-91,350.00$ EachRestrictor/Oil Separator, 18"SD-101,700.00$ EachRiprap, placedSD-1142.00$ CYTank End Reducer (36" diameter)SD-121,200.00$ EachInfiltration pond testingSD-13125.00$ HRPermeable PavementSD-14Permeable Concrete SidewalkSD-15Culvert, Box __ ft x __ ftSD-16SUBTOTAL SPECIALTY DRAINAGE ITEMS:1,436.001,716.00(B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention PondSF-1Each Detention TankSF-2Each Detention VaultSF-3Each Infiltration PondSF-4Each Infiltration TankSF-5Each Infiltration VaultSF-6Each Infiltration TrenchesSF-7Each Basic Biofiltration SwaleSF-8Each Wet Biofiltration SwaleSF-9Each WetpondSF-10Each WetvaultSF-11Each Sand FilterSF-12Each Sand Filter VaultSF-13Each Linear Sand FilterSF-14Each Proprietary FacilitySF-15Each Bioretention FacilitySF-161,500.00$ Each SUBTOTAL STORMWATER FACILITIES:(B)(C)(D)(E)Page 4 of 5Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 5/16/2019 CED Permit #:17-000389ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostQuantity Remaining (Bond Reduction) (B)(C)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESWRITE-IN-ITEMS (INCLUDE ON-SITE BMPs)WI-1WI-2WI-3WI-4WI-5WI-6WI-7WI-8WI-9WI-10WI-11WI-12WI-13WI-14WI-15SUBTOTAL WRITE-IN ITEMS:DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:7,835.004,436.003,639.00SALES TAX @ 10%783.50443.60363.90DRAINAGE AND STORMWATER FACILITIES TOTAL:8,618.504,879.604,002.90(B) (C) (D) (E)Page 5 of 5Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 04/26/2017Printed 5/16/2019 Matveyev Short Plat Technical Information Report Appendix C Operations and Maintenance Matveyev Short Plat Technical Information Report Appendix D Full WWHM2012 Output WWHM2012 PROJECT REPORT Storm Design 5/16/2019 3:20:16 PM Page 2 General Model Information Project Name:Storm Design Site Name: Site Address: City: Report Date:5/16/2019 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2018/10/10 Version:4.2.16 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Storm Design 5/16/2019 3:20:16 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.372 Pervious Total 0.372 Impervious Land Use acre ROADS MOD 0.038 DRIVEWAYS MOD 0.04 SIDEWALKS FLAT 0.01 Impervious Total 0.088 Basin Total 0.46 Element Flows To: Surface Interflow Groundwater Storm Design 5/16/2019 3:20:16 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.28 Pervious Total 0.28 Impervious Land Use acre ROOF TOPS FLAT 0.15 DRIVEWAYS MOD 0.04 Impervious Total 0.19 Basin Total 0.47 Element Flows To: Surface Interflow Groundwater Storm Design 5/16/2019 3:20:16 PM Page 5 Routing Elements Predeveloped Routing Storm Design 5/16/2019 3:20:16 PM Page 6 Mitigated Routing Storm Design 5/16/2019 3:20:16 PM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.372 Total Impervious Area:0.088 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.28 Total Impervious Area:0.19 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.074499 5 year 0.10966 10 year 0.135944 25 year 0.172646 50 year 0.202577 100 year 0.234778 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.097488 5 year 0.134095 10 year 0.160649 25 year 0.196916 50 year 0.225955 100 year 0.256773 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.122 0.148 1950 0.121 0.138 1951 0.070 0.088 1952 0.041 0.058 1953 0.038 0.062 1954 0.059 0.079 1955 0.063 0.087 1956 0.067 0.083 1957 0.083 0.108 1958 0.051 0.074 Storm Design 5/16/2019 3:20:52 PM Page 8 1959 0.046 0.065 1960 0.077 0.094 1961 0.062 0.085 1962 0.040 0.064 1963 0.068 0.088 1964 0.062 0.075 1965 0.088 0.113 1966 0.047 0.064 1967 0.119 0.135 1968 0.107 0.139 1969 0.079 0.102 1970 0.068 0.091 1971 0.083 0.111 1972 0.110 0.133 1973 0.037 0.055 1974 0.087 0.109 1975 0.087 0.111 1976 0.065 0.083 1977 0.060 0.077 1978 0.076 0.095 1979 0.071 0.114 1980 0.154 0.166 1981 0.067 0.096 1982 0.129 0.159 1983 0.080 0.101 1984 0.049 0.070 1985 0.067 0.096 1986 0.069 0.088 1987 0.072 0.113 1988 0.035 0.063 1989 0.055 0.085 1990 0.222 0.246 1991 0.160 0.182 1992 0.057 0.071 1993 0.041 0.055 1994 0.033 0.054 1995 0.058 0.084 1996 0.115 0.123 1997 0.081 0.103 1998 0.070 0.085 1999 0.179 0.221 2000 0.074 0.099 2001 0.058 0.090 2002 0.110 0.139 2003 0.105 0.120 2004 0.162 0.202 2005 0.066 0.087 2006 0.066 0.083 2007 0.207 0.224 2008 0.151 0.175 2009 0.091 0.111 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.2225 0.2460 2 0.2068 0.2245 3 0.1795 0.2207 Storm Design 5/16/2019 3:20:52 PM Page 9 4 0.1624 0.2017 5 0.1600 0.1820 6 0.1537 0.1752 7 0.1515 0.1660 8 0.1294 0.1592 9 0.1225 0.1483 10 0.1211 0.1390 11 0.1194 0.1390 12 0.1147 0.1380 13 0.1102 0.1352 14 0.1100 0.1334 15 0.1066 0.1229 16 0.1049 0.1197 17 0.0914 0.1144 18 0.0877 0.1134 19 0.0872 0.1126 20 0.0868 0.1108 21 0.0833 0.1106 22 0.0832 0.1106 23 0.0807 0.1089 24 0.0802 0.1079 25 0.0791 0.1027 26 0.0769 0.1019 27 0.0759 0.1012 28 0.0740 0.0989 29 0.0724 0.0965 30 0.0710 0.0962 31 0.0701 0.0948 32 0.0700 0.0935 33 0.0692 0.0913 34 0.0682 0.0897 35 0.0677 0.0882 36 0.0674 0.0881 37 0.0673 0.0880 38 0.0665 0.0873 39 0.0664 0.0868 40 0.0662 0.0854 41 0.0654 0.0852 42 0.0629 0.0846 43 0.0622 0.0844 44 0.0617 0.0827 45 0.0601 0.0827 46 0.0585 0.0825 47 0.0584 0.0793 48 0.0577 0.0775 49 0.0570 0.0750 50 0.0550 0.0744 51 0.0510 0.0710 52 0.0488 0.0701 53 0.0474 0.0647 54 0.0457 0.0643 55 0.0411 0.0637 56 0.0406 0.0626 57 0.0402 0.0624 58 0.0384 0.0584 59 0.0368 0.0552 60 0.0347 0.0550 61 0.0333 0.0539