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010 Preliminary Technical Information Report Table of Contents Section 1. Project Overview Section 2. Conditions and Requirements Summary Section 3. Off-Site Analysis Section 4. Flow Control & Water Quality Facility Analysis and Design Section 5. Conveyance System Analysis and Design Section 6. Special Reports and Studies Section 7. Other Permits Section 8. ESC Analysis and Design Section 9. Bond Quantities, Facility Summaries, & Declaration of Covenant Section 10. Operations and Maintenance Manual List of Figures 1.1 Vicinity Map 1.2 Existing Site Conditions 1.3 Proposed Site Conditions 1.4 Soils Map 3.1 Site Topography 3.2 Downstream Analysis Flow Path Appendix A Developed Basin Map B Hydrology Model Output \\esm8\engr\esm-jobs\1886\001\016-0016\document\rprt-003.docx 1. Project Overview The purpose of this report is to encapsulate the documents and analysis required by the Drainage Review in the 2016 King County Surface Water Design Manual (SWDM). Existing Site: The proposed Greenline Business Park project site is located in the NE and SE quarters of Section 16, Township 21 North, Range 04 East, W.M. in the City of Federal Way, WA. More specifically, the project site is located on the west side of Weyerhaeuser Way S between S 336th Street & S 323rd Street. The project will include 4 parcels on approximately 146 acres (162104-9030, 162104-9013, 162104-9056, and 152104-9178) zoned as CP-1 and will be developed in accordance with the applicable City of Federal Way code. Additionally, the property is subject to the Concomitant Pre-Annexation Zoning Agreement dated August 23, 1994. See Figure 1.1 for a vicinity map and Figure 1.2 for a visual representation of the existing site conditions. Existing Site Hydrology: The existing site is partially developed with a commercial building and associated parking lots, outbuildings, paved driveways, and landscaped areas. The remainder of the site is predominantly forest with some pasture. The property slopes gently to the south and east at 0 - 8%. Stormwater runoff generally drains south to S 336th Street and into the existing stormwater drainage system. A portion of the site drains to the Weyerhaeuser Way S and is estimated to outfall to North Lake. The site is located in the Hylebos Creek drainage basin (WRIA number: 10). See Section 3 for more information. Proposed Site Improvements: The proposed development includes the demolition of existing parking lots, clearing, grading, and the construction of 3 new commercial buildings with parking lots, access roads, utility services, and stormwater facilities on approximately 78 acres as well as the associated frontage improvements along Weyerhaeuser Way S. Figure 1.3 illustrates the Proposed Site Conditions and Section 4 describes in more detail the proposed developed areas. Proposed Site Hydrology: The proposed onsite stormwater conveyance system will collect and convey runoff from the developed project site to the stormwater drainage system in the Right-of-Way (ROW) of S 336th Street and Weyerhaeuser Way S. The developed project site will drain to the south and east boundaries of the site, discharging to the Weyerhaeuser Pond and North Lake respectively, which are the natural discharge locations for the site. See Sections 4 and 5 of this report for more information. Stormwater Runoff Mitigation Standard: As detailed in the pre-application meeting notes, the proposed development will comply with Level 2 Flow Control, Basic and Enhanced Water Quality Treatment per the SWDM. See Section 4 for more information. Soils on the Project Site: The Soils Map and Geotechnical Engineering Report indicate the soils onsite include Alderwood gravely sandy loam, 0 - 8% slopes. See Figure 1.4 and the Geotechnical Engineering Report included under separate cover for more information. Flow Control BMP’s: All applicable Flow Control BMP’s are listed and explained in Section 4 of this report. AAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAXFMRE002 E002 E002E002Ρ 2 2 5 Σ Γ Ρ Σ ς∆Ξ∆ΘΓ ≅ ∆ Τ Ρ ∆ Θ ς ≅ Ξ Ρ − µ ΡΒ≅Κ∆9 0! < 0 50 0//& 200100 ΑΤΗΚΧΗΜΦ !≅! 527+/// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 331−26,337−76 ΑΤΗΚΧΗΜΦ !Α! 171+4// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 31/−//,313−64 ΑΤΗΚΧΗΜΦ !Β! 036+4// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 311−//,313−4 ∆ΩΗΡΣΗΜΦ ςΣΒ ΑΤΗΚΧΗΜΦ ΕΕ<326−// NO.DESCRIPTION/DATE BY REVISIONS DWG. NAME DESIGNED BY: DRAWN BY: CHECKED BY: DATE: OF SHEETS JOB NO.\\\\Esm8\\engr\\ESM-JOBS\\1886\\001\\016-0016\\exhibits\\EN-06.dwg11/2/2017 9:44 AMPlotted:File:Plotted By: Tony AblemanEVERETTFEDERAL WAYΒ Ν Μ Ρ Τ Κ Σ Η Μ Φ ∆ Μ Φ Η Μ ∆ ∆ Θ ΡΚ Κ ΒCivil EngineeringProject ManagementLand SurveyingLandscape ArchitectureLand Planningwww.esmcivil.com(253) 838-6113(425) 297-9900Public WorksΕδχδθκ ςξ+ ς≅ 87//2223// 7σγ ≅υδ Ρ+ Ρτησδ 1/4Ε∆Χ∆Θ≅Κ ς≅Ξ Β≅ΛΟΤΡ+ ΚΚΒΦΘ∆∆ΜΚΗΜ∆ ΑΤΡΗΜ∆ΡΡ Ο≅ΘϑPROPOSED SITE CONDITIONSWASHINGTONCITY OF FEDERAL WAY1886-001-016 EN-06 LGB JJH 11/02/2017 ΕΗΦ 0−2 0 0 ΗΜΣ∆ Θ Ρ Σ ≅ Σ ∆ 4 \A1;9' RIGHT-OF-WAY DEDICATION \A1;39' \A1;30' SETBACK \A1;30' SETBACK \A1;9' RIGHT-OF-WAY DEDICATION ΟΝΜΧ 1 Χ∆Σ∆ΜΣΗΝΜ ΟΝΜΧ 0 Χ∆Σ∆ΜΣΗΝΜ ΟΝΜΧ 2 Χ∆Σ∆ΜΣΗΝΜ ΟΝΜΧ 3 Χ∆Σ∆ΜΣΗΝΜ ΟΝΜΧ 4 Χ∆Σ∆ΜΣΗΝΜ Κ∆Φ∆ΜΧ STORM DRAINAGE SANITARY SEWER WATER FIRE HYDRANT CATCH BASIN ROOF DRAIN LINE SANITARY SEWER MANHOLE Soil Map—King County Area, Washington (95 Acre Short Plat) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/6/2016 Page 1 of 352391005239200523930052394005239500523960052397005239800523990052400005239100523920052393005239400523950052396005239700523980052399005240000552600552700552800552900553000553100553200553300553400553500553600553700553800553900554000 552600 552700 552800 552900 553000 553100 553200 553300 553400 553500 553600 553700 553800 553900 554000 47° 18' 41'' N 122° 18' 18'' W47° 18' 41'' N122° 17' 7'' W47° 18' 10'' N 122° 18' 18'' W47° 18' 10'' N 122° 17' 7'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 300 600 1200 1800 Feet 0 100 200 400 600 Meters Map Scale: 1:6,840 if printed on A landscape (11" x 8.5") sheet. Warning: 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: http://websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 11, Sep 14, 2015 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 8, 2014—Jul 15, 2014 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—King County Area, Washington (95 Acre Short Plat) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/6/2016 Page 2 of 3 Map Unit Legend King County Area, Washington (WA633) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AgB Alderwood gravelly sandy loam, 0 to 8 percent slopes 104.7 99.6% AgC Alderwood gravelly sandy loam, 8 to 15 percent slopes 0.4 0.4% Totals for Area of Interest 105.1 100.0% Soil Map—King County Area, Washington 95 Acre Short Plat Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/6/2016 Page 3 of 3 2. Conditions and Requirements Summary Review of the 9 Core Requirements and 5 Special Requirements This section describes how the project will meet the SWDM Core and Special Requirements. Core Requirement No. 1 Discharge at the Natural Location Stormwater runoff generated from the developed project site is estimated to drain south and east to the S 336th Street and Weyerhaeuser Way S, respectively. Thence runoff is conveyed to North Lake and to Stream AC, which continues south to the Weyerhaeuser Pond. Both are the natural discharge locations for the site. Core Requirement No. 2 Off-site Analysis The off-site and downstream analyses are documented in Section 3 of this report. Core Requirement No. 3 Flow Control Level 2 Flow Control is required per the pre-application meeting notes for this project, which will be met by proposed detention ponds and storage in the existing Weyerhaeuser Pond. See Section 4 of this report for more information. Core Requirement No. 4 Conveyance System Stormwater conveyance will be provided for the proposed and existing conveyance systems per Section 5 of the SWDM. Calculations will be provided in the final TIR. Core Requirement No. 5 Erosion and Sediment Control Erosion and sediment controls to prevent the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties will be provided on the construction plans. Core Requirement No. 6 Maintenance and Operations The Operations and Maintenance manual will be included with the final TIR. Core Requirement No. 7 Financial Guarantees and Liability All drainage facilities constructed or modified for projects will comply with the financial guarantee requirements as provided in the King County Bond Quantities Worksheet. Bond Quantities will be provided in the final TIR. Core Requirement No. 8 Water Quality Basic and Enhanced Water Quality Treatment is required per the pre-application meeting notes and will be provided as described in Section 4. Core Requirement No. 9 Flow Control BMP’s All applicable Flow Control BMP’s are listed and discussed in Section 4 of this report. Special Requirement No. 1 Other Adopted Area-Specific Requirements There are no master drainage plans, basin plans, salmon conservation plans, stormwater compliance plans, flood hazard reduction plan updates, or shared facility drainage plans for this project. Special Requirement No. 1 does not apply. Special Requirement No. 2 Flood Hazard Area Delineation The developed project site location is not in a 100-year floodplain. Special Requirement No. 2 does not apply. Special Requirement No. 3 Flood Protection Facilities The developed project site is not protected by an existing flood protection facility. The proposed site improvements do not include the modification of an existing flood protection facility. Special Requirement No. 3 does not apply. Special Requirement No. 4 Source Control The project will follow the King County Stormwater Pollution Prevention Manual and King County Code 9.12 to identify and implement source controls as needed. Due to the proposed use of the project site, source control is not required; therefore, Special Requirement No. 4 does not apply. Special Requirement No. 5 Oil Control The proposed development is commercial and (according to the definition provided in the SWDM), portions of the project site qualify as a “high-use site” due to vehicle fleet size; therefore, Special Requirement No. 5 does apply. Implementation details regarding oil control will be provided in the final TIR. 3. Off-Site Analysis A Level 1 downstream analysis has been performed for the site. Task 1: Study Area Definition and Maps The study area consists of the project site and 1/4 mile downstream flow path for runoff released from the existing site. See Figure 1.2 and Figure 3.2 for the Existing Site Conditions and Downstream Analysis Flow Path exhibits. Task 2: Resource Review Flow Control Map According to the pre-application meeting notes, the project is required to comply with Level 2 Flow Control criteria. Soil Survey Map Web Soil Survey maps the soils onsite include Alderwood gravely sandy loam, 0 - 8% slopes. Refer to the Geotechnical Engineering Report attached under separate cover for more detail. King County iMap According to iMap, the project site is NOT mapped in any of the following areas: - Landslide Hazard area - Coal Mine Hazard Areas - Erosion Hazard area - 100 Year Floodplains - Critical Aquifer Recharge Area - Seismic Hazard area King County iMap and the Pre-Application Conference Notes The project site has the following areas mapped onsite and nearby: - Streams & Wetlands See Figure 3.1 for more information regarding the environmental hazards near the project site. Road Drainage Problems None noted Wetlands Inventory According to iMap, the Critical Areas Review, and the 1990 King County Wetlands Inventory Notebooks there are no recorded wetlands on the existing project site. However, the wetland biologist has located onsite wetland areas and there are wetland areas downstream of the developed project site. See Figure 1.2 for Existing Site Conditions and the wetland report for more information. Migrating River Study None noted Downstream Drainage Complaints According to iMap, there are no relevant downstream drainage complaints within the scope of this project. Task 3: Field Inspection (Level 1 Inspection) A Level 1 Downstream Analysis was completed by ESM Consulting Engineers, LLC in the early afternoon on October 5, 2016, when it was sunny and 65°F. During the inspection it was found that the project site has no apparent upstream offsite areas draining to the property. Stormwater runoff from the existing site’s lawn, vegetated areas, roof, roads, access ways, and parking lot is estimated to flow across the property to the south and east boundaries of the site and drain to the public right-of-way. From there, stormwater runoff south of the site’s existing south entrance is collected in the gutter along the west side of Weyerhaeuser Way S and continues south to S 336th Street. The runoff is conveyed in a piped system or via roadside ditch in the area near the roundabout. Once past the roundabout, the runoff crosses under S 336th Street in two 12 inch diameter concrete culverts and continues to the Weyerhaeuser Pond via established drainage paths. Stormwater runoff north of the site’s existing south entrance is estimated to be collected in a road side ditch and conveyed east under Weyerhaeuser Way S to North Lake via two culvert pipes. There did not appear to be any flooding issues over any of the roadways adjacent to, and downstream of, the project site. See Figure 3.2 Downstream Analysis Flowpath for further information and the approximate existing basin area draining to North Lake. The site was revisited around noon on January 18, 2017, when it was heavily raining. Following the flow of stormwater south of S 336th Street, stormwater was routed in a drainage ditch with no apparent restrictions on its way to the Weyerhaeuser Pond. The flow increased significantly once it was joined with the outflow from North Lake. At that point it appeared that the capacity of the drainage ditch was increased sufficiently to convey the stormwater runoff. Task 4: Drainage Description and Problem Descriptions According to iMap, the project site is in the Hylebos Creek (King County WRIA number: 10) drainage basin. Hylebos Creek is located approximately 0.3 miles to the west of the project and separated by I-5. No drainage problems are known to exist in the site’s present condition. There is an existing Sphagnum Bog located adjacent to the northwest corner of the project site (parcel 215465-0170). However, it is not part of the existing or developed drainage basin, and no associated drainage problems are known. Task 5: Mitigation of Existing or Potential Problems No existing or potential problems were observed with the existing drainage system within the scope of the downstream analysis. Therefore, no further mitigation is proposed. - Date: 10/7/2016 Notes: The information included on this map h as been compiled by King County sta ff from a varie ty of sources and is subject tochange without notice. King County makes no representations or warrantie s, express or implied, as to accuracy,completeness, timeliness, or rights to the use of such information. This document is not inten ded for use as a surveyproduct. King County shall not be liab le for any general, special, indirect, incidental, or consequential damages including,but not limited to, lost revenues or lost p rofits resulting from the use or misuse of the information contained on this map.Any sale of this map or information on th is map is prohibited except by written permission of King County. Le gend Parcels Bonde d Commercial -MF Commercial -SF Construction DOT FM D Region al Residential Drain age comp lai nts Potential land slidehazard a rea s (2016,see explan ation--->) Potential stee p slop ehazard a rea s (2016,see explan ation--->) Erosion haza rd (199 0SAO) Sei smic h azard (1 990SAO) Coal mi ne h azar d(19 90 SAO) cl ass 1 cl ass 2 perennia l cl ass 2 salmo nid cl ass 3 uncla ssified Wetland (1990 S AO ) Sensitive area noticeon title - Date: 10/5/2016 Notes: The information included on this map has been compiled by King County staff from a variety of sources and is subject tochange without notice. King County makes no representations or warranties, express or implied, as to accuracy,completeness, timeliness, or rights to the use of such information. This document is not intended for use as a surveyproduct. King County shall not be liable for any general, special, indirect, incidental, or consequential damages including,but not limited to, lost revenues or lost profits resulting from the use or misuse of the information contained on this map.Any sale of this map or information on this map is prohibited except by written permission of King County. Legend Parcels Streams Point 1: Looking south, east (across the road), and at the culvert inlet. Stormwater collected in the roadside ditch is conveyed to this culvert on the west side of Weyerhaeuser Way SW where it crosses the road and continues east to North Lake. Culvert Point 2: Looking south on the west side of Weyerhaeuser Way SW Water from the site that flows to Weyerhaeuser Way SW is routed to this culvert via roadside ditch and continues east. Looking north on the east side of Weyerhaeuser Way SW Point 3: Looking north on the west side of Weyerhaeuser Way SW. Stormwater runoff south of the south entrance to the existing site is collected by this roadside ditch. Point 3: Looking south on the west side of Weyerhaeuser Way SW. From the ditch, stormwater enters the existing stormwater conveyance system in this culvert. Point 3: Looking south toward the roundabout. Stormwater runoff not collect further north is collected by this ditch along the south boundary of the site and drains to Point 4. Point 4: Looking south at the inlet of the pipes crossing S 336th Street. Point 5: Looking west on the south side of S 336th Street where the stormwater runoff from the project site crosses and drains to Weyerhaeuser Pond. 4. Flow Control & Water Quality Facility Analysis and Design Existing Site Hydrology: The existing site is partially developed with a commercial building and associated parking lots, outbuildings, paved driveways, and landscaped areas. The remainder of the site is predominantly forest with some pasture. The property slopes gently to the south and east at 0 - 8%. Stormwater runoff generally drains south to the S 336th Street public ROW and into the existing stormwater drainage system. A small portion of the site drains east to the Weyerhaeuser Way S and is estimated to outfall to North Lake. The site is located in the Hylebos Creek drainage basin (WRIA number: 10). See Section 3 for more information. Due to the topography of the project site, the existing 5 onsite basins shown in Figure 1.3 drain to the south and east borders, which are the Points of Compliance. From there, stormwater runoff is conveyed to North Lake (Basin 1) and Weyerhaeuser Pond (Basins 2-5). As required by the SWDM, the existing basins have been modeled as pre- developed forested, and the areas are described in Table 4.0 below (totaling 78.22 acres). Table 4.0 Land Use ( Acres ) Basin 1 Basin 2 Basin 3 Basin 4 Basin 5 C, Forest 11.48 44.33 4.96 5.82 11.63 Developed Site Hydrology: The developed Basins 1-5 (totaling 78.22 acres) are generally described below, shown in Table 4.1, and illustrated on the Developed Basin Map in Appendix A. Basin 1 The proposed drainage Basin 1 consists of 11.48 acres of developed area. This area discharges in the same direction as the existing 24 acre drainage basin that drains to the wetlands and associated buffers on the east side of Weyerhaeuser Way S and continues to North Lake, which is the natural discharge location for the basin. The developed area includes the eastern portion of the proposed Building A, associated standard parking and landscaped areas, and the proposed Pond 1 area. Basin 2 The proposed drainage Basin 2 consists of 43.94 acres of developed area. This area discharges to the wetlands and associated buffers on the east side of Interstate 5 and continues to Stream AC, which continues south to the Weyerhaeuser Pond, which is the natural discharge location for the basin. The developed area includes the western portion of the proposed Building A, associated truck and standard parking lot areas, relocated Tech Center parking lot areas, landscaped parking lot areas, and the proposed Pond 2 area. A small 0.39 acre portion of Basin 2 drains directly to Weyerhaeuser Way S and will bypass Pond 2, which has been modeled as bypass in WWHM. Basin 3 The proposed drainage Basin 3 consists of 4.96 acres of developed area. This area discharges to Stream AC, which continues south to the Weyerhaeuser Pond, which is the natural discharge location for the basin. The developed area includes Building C clean roof runoff as well as the proposed Pond 3 area. Basin 4 The proposed drainage Basin 4 consists of 5.82 acres of developed area. This area discharges to Stream AC, which continues south to the Weyerhaeuser Pond, which is the natural discharge location for the basin. The developed area includes truck and standard parking lot areas associated with Building C, landscaped parking lot areas and the proposed Pond 4 area. Basin 5 The proposed drainage Basin 5 consists of 11.06 acres of developed area. This area discharges to Stream AC, which continues south to the Weyerhaeuser Pond, which is the natural discharge location for the basin. The developed area includes Building B, associated truck and standard parking lot areas, landscaped parking lot areas, and the proposed Pond 5 area. A small 0.57 acre portion of Basin 5 drains directly to Weyerhaeuser Way S and will bypass Pond 5, which has been modeled as bypass in WWHM. Table 4.1 Land Use ( Acres ) Basin 1 Basin 2 Basin 3 Basin 4 Basin 5 Developed Developed By pass Developed Developed Developed By pass C, Lawn 2.41 7.50 0.02 1.51 1.26 1.54 0.06 Road and Parking 1.82 21.54 0.37 0.00 4.12 2.66 0.51 Roof 7.02 13.13 0.00 3.31 0.00 6.49 0.00 Sidewalk 0.20 1.63 0.00 0.00 0.39 0.33 0.00 Pond Access 0.03 0.14 0.00 0.14 0.05 0.04 0.00 Impervious Total 9.07 36.44 0.37 3.45 4.56 9.52 0.51 Basin Total 11.48 43.94 0.39 4.96 5.82 11.06 0.57 The frontage improvements along the majority of both sides of Weyerhaeuser Way S consist of approximately 5.5 acres of ROW dedication, 2.4 acres of asphalt pavement, 1.7 acres of sidewalk, and 1.4 acres of landscaping. The northern portion of the existing roadway and associated frontage improvements discharges in the same direction as the existing 24 acre drainage basin that drains to the wetlands and associated buffers on the east side of Weyerhaeuser Way S and continues to North Lake. The remaining portion of the existing roadway and associated frontage improvements flows southeast to the Weyerhaeuser Pond, which is the natural discharge location for the basin. Performance Standards: Stormwater systems onsite are to be designed to mitigate runoff generated from the project per the requirements of the SWDM, specifically the Level 2 Flow Control standards per the Pre-application meeting notes for this project. The existing building and areas to remain will be retrofitted to meet the Level 2 Flow Control standard. The facility size is required to be determined by an approved hydrology model per the SWDM. Flow Control System: The approved hydrology model used to size the detention portion of Ponds 1-5 was the Western Washington Hydrology Model (WWHM) version 2012. The default sizing from that software complies with the Level 2 Flow Control standards. As modeled in WWHM, Basins 2 and 5 mitigated developed flows include flows bypassing the stormwater facilities. The pre-developed and developed project site mitigated flow rates are given in Table 4.2 and comply with the Level 2 Flow Control standards. The estimated volumes required and provided are given in Table 4.3. The WWHM output is provided in Appendix B. Table 4.2 Peak Flows ( cfs ) Basin 1 Basin 2 Basin 3 Basin 4 Basin 5 Return Period Pre Dev Mit Pre Dev Mit Pre Dev Mit Pre Dev Mit Pre Dev Mit 2 Year 0.34 0.18 1.30 0.71 0.15 0.09 0.17 0.10 0.34 0.80 5 Year 0.53 0.27 2.05 0.98 0.23 0.14 0.27 0.16 0.54 1.56 10 Year 0.64 0.34 2.47 1.18 0.28 0.19 0.32 0.21 0.65 2.34 25 Year 0.75 0.44 2.91 1.45 0.33 0.25 0.38 0.28 0.76 3.75 50 Year 0.83 0.52 3.19 1.67 0.36 0.30 0.42 0.35 0.84 5.20 100 Year 0.89 0.61 3.43 1.91 0.38 0.36 0.45 0.42 0.90 7.09 Table 4.3 Stormwater Detention Volume (acre-feet) Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Required 5.37 19.03 1.71 2.44 4.88* Provided 5.78 19.33 2.05 3.37 1.45 Safety Factor 8% 2% 20% 38% N/A * 3.43 acre-feet to Weyerhaeuser Pond. The Weyerhaeuser Pond’s headworks were modified and approved in July of 2004 to increase the live storage by 200,000 cubic feet (4.59 acre-feet). The pond’s weir was adjusted to obtain this additional live storage. This project preliminarily proposes to discharge 3.43 acre-feet of additional live storage from Pond 5 to the Weyerhaeuser Pond, to use the available additional live storage. Flow control for the proposed frontage improvements will be provided in relocated roadside swales, matching the drainage flow paths for the existing pavement, with additional detention capacity in the Weyerhaeuser Pond. Detailed flow control analysis will be completed with the final frontage improvement plans, which will also require relocating existing utility infrastructure, extending existing culverts, as well as new pavement channelization. Water Quality System: The approved hydrology model used to size the Ponds 1-5 was WWHM version 2012. Basin 1 consists of the eastern portion of Building A and standard parking areas. A Modular Wetlands filter vault (or approved equivalent) will be placed before detention; therefore, it will be sized with the WWHM water quality flow rate and meet Basic Water Quality Treatment. A Modular Wetlands filter vault (or approved equivalent) sized with the WWHM 2-year mitigated flow rate will be provided for Basins 2, 4, and 5 to meet the Enhanced Water Quality Treatment standards in Section 1.2.8 of the SWDM. The eastern portion of Building A in Basin 1, the western portion of Building A in Basin 2, and Building B in Basin 5’s roof runoff is considered clean, thus not requiring water quality treatment, and will be conveyed directly into their respective detention Ponds 1, 2, and 5. Basin 3 only consists of clean roof runoff from Building C and therefore does not require water quality treatment. The roof material to be used on the proposed Buildings A, B, and C will be TOP and is considered to be non-leaching which complies with the requirements specified in Section 1.2.8 of the SWDM. Oil control is required for the parking lot areas and implementation details will be provided in the final TIR. The required and provided treatment rates are given in Table 4.5. The WWHM output is provided in Appendix B. * 2 year mitigated flow rate for Enhanced Water Quality Treatment. Water quality for the asphalt pavement portion of the proposed frontage improvements will be provided in relocated roadside swales, matching the drainage flow paths for the existing pavement. Detailed flow control analysis will be completed with the final frontage improvement plans, which will also require relocating existing utility infrastructure, extending existing culverts, as well as new pavement channelization. Table 4.5 Water Quality Flow Rate ( cfs ) Basin 1 Basin 2 Basin 4 Basin 5 Required 0.31 0.71* 0.10* 0.80* Flow Control BMPs Flow control BMPs have been preliminarily evaluated for the project site as outlined in the SWDM under Section 1.2.9.2.2 – Large Lot BMP Requirements. These BMP’s are described below in the required order, with feasibility determined and the portion of applicable area credited as mitigated, which should be no less than 10% of the total site area – 7.82 acres. Full Dispersion There are multiple native vegetated areas surrounding the project site that will be left undisturbed. The areas on the east side of the project site are not large enough to accommodate a minimum flowpath of 100 feet in length. The areas on the west side of the project site consist mostly of wetlands, streams and associated buffers and are not feasible for full dispersion. The areas on the north side of the project site are upstream, thus also not feasible for full dispersion. In summary, Full Dispersion is deemed to be infeasible for this project site. Full Infiltration The Geotechnical Engineering Report states that “…there is very limited infiltration potential at this site. Because of these factors we recommend that stormwater detention be used for site development.” Because of this recommendation, Full Infiltration (specified in Section C.2.2.2.1) minimum requirements cannot be met; hence, Full Infiltration is infeasible for this project site. Limited Infiltration Limited Infiltration (specified in Section C.2.3) has the same minimum design requirements as Full Infiltration. Since Full Infiltration has been deemed infeasible, Limited Infiltration is also infeasible for this project site. Bioretention Bioretention (specified in Section C2.6) may be feasible, using raingardens pending further geotechnical field investigation (to be completed with final design). Permeable Pavement, Permeable Pavement (specified in Section C2.7) may be feasible for the onsite and frontage non-pollution generating impervious concrete sidewalk, pending further geotechnical field investigation (to be completed with final design). Basic Dispersion As discussed above for Full Dispersion, the native vegetated areas deemed to be infeasible for Basic Dispersion. If the impervious area credited as mitigated is less than the threshold specified in Flow Control BMPs above, then (according to Section 1.2.9.2.2.5 of the SWDM) a fee in lieu must be paid OR one or more the following BMPs must be implemented to achieve compliance: Reduced Impervious Surface Credit This project is larger than 250,000 square feet (Section C.2.9.2), cannot use wheel strip driveways (Section C.2.9.3) due to the proposed parking layout, cannot implement a minimum disturbance foundation (Section C.2.9.4) due to the building type, and open grid decking over pervious surface (Section C.2.9.5) is not applicable. Therefore, minimum design requirement #1 (specified in Section C.2.9.1) cannot be met; hence, the Reduced Impervious Surface Credit cannot be claimed for the proposed site improvements. Native Growth Retention Credit The minimum design requirement that any area of target impervious surface credited as mitigated by this credit must be directed to vegetated pervious areas on the site or discharged through a perforated pipe connection in accordance with Section C.2.11. While it is not feasible to direct stormwater runoff to those surfaces due to the elevation difference of the applicable vegetated pervious areas, the perforated pipe connection will be provided to the roof downspouts for the three proposed buildings. Out of the total parcel area (146 acres), the undisturbed native vegetation area of 56.9 acres mitigates for 16.26 acres of impervious area, which is equivalent to 21% of the total project site area (78.22 acres) and 25% of the total impervious area (63.98 acres). The native vegetated area used for this credit requires specific covenants, per SWDM, and these requirements have been preliminarily compared with the Weyerhaeuser Company Concomitant Pre-Annexation Zoning Agreement (CZA). The requirements in the SWDM appear to not conflict with the CZA, therefore, native growth retention appears to be feasible for the project site and will be confirmed with final design. Soil Amendment Minimum Requirement #6 All new pervious surfaces will be amended per Section 1.2.9.2.2.6 of the SWDM to satisfy the requirements specified therein (notes will be added on the final landscape plans). Roof Downspout Minimum Requirement #7 All roof downspouts will be shown on the final construction plans to connect to the storm system via Perforated Pipe Connection (as specified in Section C.2.11 of the SWDM). In summary, the project site will implement the following flow control BMPs, if determined feasible during final design: Bioretention and Permeable Pavement for the project site and frontage improvements, pending further geotechnical field investigation. If the impervious area credited as mitigated is not sufficient, a fee in lieu will be paid, or the Native Growth Retention Credit will be implemented. Additionally, the project will amend soils and use perforated pipe connections for downspouts. 5. Conveyance System Analysis and Design Onsite Conveyance System: Runoff from the developed project site will be collected by the onsite conveyance system. The proposed stormwater drainage system is composed of catch basin structures with pipes. The proposed stormwater drainage system will be designed to convey the 25-year peak flow rate generated by the developed tributary basin as required by the SWDM. The system will contain the 100-year flow within the catch basins without any backwater issues. A conveyance and backwater analysis will be completed to verify the capacity of the critical pipes in the system with the final TIR. Outlet Conveyance System: The proposed detention Pond 1 will discharge pre-developed forested stormwater runoff to the existing wetland buffers and continues to North Lake for an estimated maximum 100 year flow of 0.61 cfs, which is less than the 100 year flow of 1.87 cfs for the estimated 24 acre forested basin that currently drains in the same direction. The proposed water quality and detention Ponds 2 – 4 will match pre-developed conditions and discharge pre-developed forested stormwater runoff to Stream AC, which continues south to the Weyerhaeuser Pond for a combined 100 year discharged flow rate of 2.69 cfs. Furthermore, the existing forested and pasture areas that flow to Stream AC amount to approximately 14 acres and an associated 100 year flow rate of 1.58 cfs. In addition, Pond 5 will discharge 3.34 acre-feet of additional live storage to Weyerhaeuser Pond, to use the available additional live storage, which results in a 100 year discharged flow rate of 7.09 cfs. The total stormwater runoff to this location is 11.36 cfs (2.69 + 1.58 + 7.09), which is less than the existing culverts preliminary calculated flow capacity of 12.84 cfs, using a Manning’s n of 0.013. Conveyance and backwater calculations will be provided with the final TIR. 6. Special Reports and Studies The Critical Areas Report and Conceptual Mitigation Plan by Talasaea Consultants, Inc, (dated September 20, 2017) are included under separate cover. The Geotechnical Engineering Report by GeoEngineers, (dated September 19, 2017) is included under separate cover. 7. Other Permits Building and NPDES permits will be required for this project, together with permits for utility connections. These will be applied for and provided at a later date. 8. ESC Analysis and Design The Erosion and Sedimentation Control calculations will be provided with the final TIR. 9. Bond Quantities, Facility Summaries, and Declaration of Covenant The Bond Quantities worksheet will be provided with the final TIR. The Facilities Summaries and Declaration of Covenant will be evaluated with final design to determine if applicable. 10. Operations and Maintenance The Operations and Maintenance manual will be provided with the final TIR. Appendix A Developed Basin Map AAAAAAAAAAAAAAAAAAAAA AAA AAAAAAAAAAAAAAAAAAXFMRE002 E002 E002E002Ρ 2 2 5 Σ Γ Ρ Σ ς∆Ξ∆ΘΓ ≅ ∆ Τ Ρ ∆ Θ ς ≅ Ξ Ρ − µ ΡΒ≅Κ∆9 0! < 0 50 0//& 200100 NO.DESCRIPTION/DATE BY REVISIONS DWG. NAME DESIGNED BY: DRAWN BY: CHECKED BY: DATE: OF SHEETS JOB NO.\\\\Esm8\\engr\\ESM-JOBS\\1886\\001\\016-0016\\exhibits\\EN-03.dwg11/2/2017 9:39 AMPlotted:File:Plotted By: Tony AblemanEVERETTFEDERAL WAYΒ Ν Μ Ρ Τ Κ Σ Η Μ Φ ∆ Μ Φ Η Μ ∆ ∆ Θ ΡΚ Κ ΒCivil EngineeringProject ManagementLand SurveyingLandscape ArchitectureLand Planningwww.esmcivil.com(253) 838-6113(425) 297-9900Public WorksΕδχδθκ ςξ+ ς≅ 87//2223// 7σγ ≅υδ Ρ+ Ρτησδ 1/4Ε∆Χ∆Θ≅Κ ς≅Ξ Β≅ΛΟΤΡ+ ΚΚΒΦΘ∆∆ΜΚΗΜ∆ ΑΤΡΗΜ∆ΡΡ Ο≅ΘϑDEVELOPED BASIN MAPWASHINGTONCITY OF FEDERAL WAY1886-001-016 EN-03 LGB TMA 11/02/2017 ∆Μ,/2 0 0 ΗΜΣ∆ Θ Ρ Σ ≅ Σ ∆ 4 Cover Type ( Acres )Basin 1 Basin 2 Basin 2 Bypass Basin 3 Basin 4 Basin 5 Basin 5 Bypass Total C, Lawn 2.41 7.50 0.02 1.51 1.26 1.54 0.06 14.30 Road & Parking Lot 1.82 21.54 0.37 0.00 4.12 2.66 0.51 31.02 Roof 7.02 13.13 0.00 3.31 0.00 6.49 0.00 29.95 Sidewalk 0.20 1.63 0.00 0.00 0.39 0.33 0.00 2.55 Pond Access 0.03 0.14 0.00 0.14 0.05 0.04 0.00 0.40 Total 11.48 43.94 0.39 4.96 5.82 11.06 0.57 78.22 Detention Volume ( Ac-Ft ) Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Required 5.37 19.03 1.71 2.44 4.88* Provided 5.78 19.33 2.05 3.37 1.45 Safety Factor 8%2%20%38%N/A * 3.43 AC-FT stored in Weyerhaeuser Pond 11/2/2017 ΑΤΗΚΧΗΜΦ !≅! 527+/// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 331−26,337−76 ΑΤΗΚΧΗΜΦ !Α! 171+4// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 31/−//,313−64 ΑΤΗΚΧΗΜΦ !Β! 036+4// ΡΕ ΕΕ<Υ≅ΘΗ∆Ρ 311−//,313−4 ∆ΩΗΡΣΗΜΦ ςΣΒ ΑΤΗΚΧΗΜΦ ΕΕ<326−// Water Quality Flow Rate ( CFS ) Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Required 0.31 0.71*N/A 0.10*0.80* * 2 year mitigated flow rate for Enhanced Water Quality Treatment Appendix B Hydrology Model Output WWHM2012 PROJECT REPORT Pond 1 10/24/2017 4:08:55 PM Page 2 General Model Information Project Name:Pond 1 Site Name: Site Address: City: Report Date:10/24/2017 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 Pond 1 10/24/2017 4:08:55 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 11.48 Pervious Total 11.48 Impervious Land Use acre Impervious Total 0 Basin Total 11.48 Element Flows To: Surface Interflow Groundwater Pond 1 10/24/2017 4:08:55 PM Page 4 Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 2.41 Pervious Total 2.41 Impervious Land Use acre ROADS FLAT 1.82 ROOF TOPS FLAT 7.02 SIDEWALKS FLAT 0.2 POND 0.03 Impervious Total 9.07 Basin Total 11.48 Element Flows To: Surface Interflow Groundwater Pond 1 Pond 1 Pond 1 10/24/2017 4:08:55 PM Page 6 Mitigated Routing Pond 1 Bottom Length:250.00 ft. Bottom Width:200.00 ft. Depth:5 ft. Volume at riser head:5.3675 acre-feet. Side slope 1:4 To 1 Side slope 2:4 To 1 Side slope 3:4 To 1 Side slope 4:4 To 1 Discharge Structure Riser Height:4 ft. Riser Diameter:18 in. Orifice 1 Diameter:1.9 in.Elevation:0 ft. Orifice 2 Diameter:2.2 in.Elevation:2.25 ft. Orifice 3 Diameter:2.6 in.Elevation:3 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 1.147 0.000 0.000 0.000 0.0556 1.152 0.063 0.023 0.000 0.1111 1.157 0.128 0.032 0.000 0.1667 1.161 0.192 0.040 0.000 0.2222 1.166 0.257 0.046 0.000 0.2778 1.170 0.322 0.051 0.000 0.3333 1.175 0.387 0.056 0.000 0.3889 1.180 0.452 0.061 0.000 0.4444 1.184 0.518 0.065 0.000 0.5000 1.189 0.584 0.069 0.000 0.5556 1.194 0.650 0.073 0.000 0.6111 1.198 0.717 0.076 0.000 0.6667 1.203 0.783 0.080 0.000 0.7222 1.208 0.850 0.083 0.000 0.7778 1.213 0.918 0.086 0.000 0.8333 1.217 0.985 0.089 0.000 0.8889 1.222 1.053 0.092 0.000 0.9444 1.227 1.121 0.095 0.000 1.0000 1.232 1.189 0.098 0.000 1.0556 1.236 1.258 0.100 0.000 1.1111 1.241 1.327 0.103 0.000 1.1667 1.246 1.396 0.105 0.000 1.2222 1.251 1.465 0.108 0.000 1.2778 1.255 1.535 0.110 0.000 1.3333 1.260 1.605 0.113 0.000 1.3889 1.265 1.675 0.115 0.000 1.4444 1.270 1.745 0.117 0.000 1.5000 1.275 1.816 0.120 0.000 1.5556 1.280 1.887 0.122 0.000 1.6111 1.284 1.958 0.124 0.000 1.6667 1.289 2.030 0.126 0.000 1.7222 1.294 2.101 0.128 0.000 1.7778 1.299 2.174 0.130 0.000 Pond 1 10/24/2017 4:08:55 PM Page 7 1.8333 1.304 2.246 0.132 0.000 1.8889 1.309 2.318 0.134 0.000 1.9444 1.314 2.391 0.136 0.000 2.0000 1.319 2.464 0.138 0.000 2.0556 1.323 2.538 0.140 0.000 2.1111 1.328 2.612 0.142 0.000 2.1667 1.333 2.686 0.144 0.000 2.2222 1.338 2.760 0.146 0.000 2.2778 1.343 2.834 0.169 0.000 2.3333 1.348 2.909 0.187 0.000 2.3889 1.353 2.984 0.200 0.000 2.4444 1.358 3.059 0.211 0.000 2.5000 1.363 3.135 0.220 0.000 2.5556 1.368 3.211 0.229 0.000 2.6111 1.373 3.287 0.237 0.000 2.6667 1.378 3.364 0.244 0.000 2.7222 1.383 3.440 0.251 0.000 2.7778 1.388 3.517 0.258 0.000 2.8333 1.393 3.595 0.265 0.000 2.8889 1.398 3.672 0.271 0.000 2.9444 1.403 3.750 0.277 0.000 3.0000 1.409 3.828 0.283 0.000 3.0556 1.414 3.907 0.332 0.000 3.1111 1.419 3.985 0.355 0.000 3.1667 1.424 4.064 0.375 0.000 3.2222 1.429 4.144 0.391 0.000 3.2778 1.434 4.223 0.407 0.000 3.3333 1.439 4.303 0.421 0.000 3.3889 1.444 4.383 0.434 0.000 3.4444 1.449 4.464 0.447 0.000 3.5000 1.455 4.544 0.459 0.000 3.5556 1.460 4.625 0.471 0.000 3.6111 1.465 4.706 0.482 0.000 3.6667 1.470 4.788 0.493 0.000 3.7222 1.475 4.870 0.504 0.000 3.7778 1.481 4.952 0.514 0.000 3.8333 1.486 5.034 0.524 0.000 3.8889 1.491 5.117 0.534 0.000 3.9444 1.496 5.200 0.543 0.000 4.0000 1.501 5.283 0.553 0.000 4.0556 1.507 5.367 0.770 0.000 4.1111 1.512 5.451 1.159 0.000 4.1667 1.517 5.535 1.654 0.000 4.2222 1.523 5.620 2.225 0.000 4.2778 1.528 5.704 2.845 0.000 4.3333 1.533 5.789 3.487 0.000 4.3889 1.538 5.875 4.123 0.000 4.4444 1.544 5.960 4.725 0.000 4.5000 1.549 6.046 5.268 0.000 4.5556 1.554 6.132 5.734 0.000 4.6111 1.560 6.219 6.113 0.000 4.6667 1.565 6.306 6.407 0.000 4.7222 1.570 6.393 6.634 0.000 4.7778 1.576 6.480 6.917 0.000 4.8333 1.581 6.568 7.144 0.000 4.8889 1.587 6.656 7.363 0.000 4.9444 1.592 6.744 7.576 0.000 5.0000 1.597 6.833 7.783 0.000 Pond 1 10/24/2017 4:08:55 PM Page 8 5.0556 1.603 6.922 7.984 0.000 Pond 1 10/24/2017 4:08:55 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:11.48 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:2.41 Total Impervious Area:9.07 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.337522 5 year 0.530091 10 year 0.639223 25 year 0.754839 50 year 0.826383 100 year 0.887234 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.183778 5 year 0.272424 10 year 0.340504 25 year 0.437789 50 year 0.51883 100 year 0.607548 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.332 0.129 1950 0.413 0.214 1951 0.743 0.448 1952 0.234 0.118 1953 0.189 0.210 1954 0.291 0.136 1955 0.464 0.133 1956 0.369 0.275 1957 0.298 0.135 1958 0.336 0.145 Pond 1 10/24/2017 4:09:25 PM Page 10 1959 0.288 0.134 1960 0.503 0.279 1961 0.284 0.230 1962 0.176 0.119 1963 0.242 0.166 1964 0.319 0.231 1965 0.228 0.244 1966 0.219 0.143 1967 0.459 0.209 1968 0.286 0.139 1969 0.280 0.140 1970 0.231 0.184 1971 0.247 0.143 1972 0.553 0.377 1973 0.251 0.247 1974 0.273 0.143 1975 0.370 0.131 1976 0.267 0.138 1977 0.032 0.117 1978 0.235 0.194 1979 0.142 0.107 1980 0.525 0.400 1981 0.210 0.142 1982 0.403 0.259 1983 0.361 0.142 1984 0.223 0.121 1985 0.132 0.121 1986 0.585 0.171 1987 0.517 0.268 1988 0.204 0.133 1989 0.133 0.121 1990 1.082 0.283 1991 0.651 0.369 1992 0.251 0.185 1993 0.262 0.116 1994 0.088 0.105 1995 0.375 0.232 1996 0.791 0.425 1997 0.661 0.457 1998 0.150 0.124 1999 0.620 0.379 2000 0.261 0.171 2001 0.047 0.096 2002 0.286 0.205 2003 0.365 0.135 2004 0.472 0.402 2005 0.339 0.132 2006 0.400 0.275 2007 0.803 0.493 2008 1.036 0.360 2009 0.509 0.235 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.0819 0.4933 2 1.0360 0.4570 3 0.8031 0.4482 Pond 1 10/24/2017 4:09:25 PM Page 11 4 0.7909 0.4253 5 0.7432 0.4018 6 0.6611 0.3999 7 0.6515 0.3792 8 0.6200 0.3772 9 0.5850 0.3687 10 0.5535 0.3599 11 0.5245 0.2833 12 0.5175 0.2795 13 0.5087 0.2754 14 0.5026 0.2753 15 0.4724 0.2677 16 0.4638 0.2592 17 0.4589 0.2472 18 0.4134 0.2443 19 0.4032 0.2352 20 0.3996 0.2322 21 0.3753 0.2308 22 0.3697 0.2295 23 0.3691 0.2138 24 0.3648 0.2103 25 0.3615 0.2094 26 0.3389 0.2045 27 0.3356 0.1942 28 0.3315 0.1847 29 0.3188 0.1844 30 0.2979 0.1712 31 0.2909 0.1709 32 0.2878 0.1663 33 0.2863 0.1449 34 0.2860 0.1435 35 0.2835 0.1434 36 0.2801 0.1427 37 0.2729 0.1420 38 0.2673 0.1418 39 0.2617 0.1403 40 0.2610 0.1394 41 0.2514 0.1379 42 0.2512 0.1358 43 0.2470 0.1352 44 0.2422 0.1349 45 0.2345 0.1338 46 0.2342 0.1330 47 0.2310 0.1328 48 0.2283 0.1321 49 0.2231 0.1314 50 0.2195 0.1293 51 0.2096 0.1238 52 0.2042 0.1214 53 0.1894 0.1209 54 0.1764 0.1207 55 0.1495 0.1185 56 0.1417 0.1175 57 0.1332 0.1173 58 0.1324 0.1155 59 0.0879 0.1075 60 0.0468 0.1055 61 0.0318 0.0961 Pond 1 10/24/2017 4:09:25 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.1688 17736 14940 84 Pass 0.1754 16232 13975 86 Pass 0.1820 14970 12912 86 Pass 0.1887 13941 12112 86 Pass 0.1953 12857 10964 85 Pass 0.2020 11952 10160 85 Pass 0.2086 10970 9266 84 Pass 0.2153 10143 8365 82 Pass 0.2219 9467 7597 80 Pass 0.2285 8787 6678 75 Pass 0.2352 8164 5873 71 Pass 0.2418 7659 5221 68 Pass 0.2485 7099 4629 65 Pass 0.2551 6594 4021 60 Pass 0.2618 6188 3433 55 Pass 0.2684 5792 2802 48 Pass 0.2750 5431 2321 42 Pass 0.2817 5142 1945 37 Pass 0.2883 4819 1761 36 Pass 0.2950 4564 1723 37 Pass 0.3016 4271 1680 39 Pass 0.3083 4023 1635 40 Pass 0.3149 3816 1600 41 Pass 0.3215 3559 1542 43 Pass 0.3282 3341 1492 44 Pass 0.3348 3157 1408 44 Pass 0.3415 2960 1242 41 Pass 0.3481 2787 1125 40 Pass 0.3548 2618 1042 39 Pass 0.3614 2453 930 37 Pass 0.3680 2304 796 34 Pass 0.3747 2171 738 33 Pass 0.3813 2032 661 32 Pass 0.3880 1917 611 31 Pass 0.3946 1798 545 30 Pass 0.4013 1694 434 25 Pass 0.4079 1605 395 24 Pass 0.4145 1489 354 23 Pass 0.4212 1382 308 22 Pass 0.4278 1301 257 19 Pass 0.4345 1225 218 17 Pass 0.4411 1155 192 16 Pass 0.4478 1102 166 15 Pass 0.4544 1050 138 13 Pass 0.4610 997 121 12 Pass 0.4677 933 114 12 Pass 0.4743 884 106 11 Pass 0.4810 843 97 11 Pass 0.4876 790 35 4 Pass 0.4943 743 0 0 Pass 0.5009 719 0 0 Pass 0.5075 673 0 0 Pass 0.5142 633 0 0 Pass Pond 1 10/24/2017 4:09:25 PM Page 14 0.5208 600 0 0 Pass 0.5275 569 0 0 Pass 0.5341 539 0 0 Pass 0.5407 501 0 0 Pass 0.5474 475 0 0 Pass 0.5540 434 0 0 Pass 0.5607 403 0 0 Pass 0.5673 370 0 0 Pass 0.5740 351 0 0 Pass 0.5806 325 0 0 Pass 0.5872 296 0 0 Pass 0.5939 277 0 0 Pass 0.6005 257 0 0 Pass 0.6072 235 0 0 Pass 0.6138 218 0 0 Pass 0.6205 198 0 0 Pass 0.6271 180 0 0 Pass 0.6337 158 0 0 Pass 0.6404 145 0 0 Pass 0.6470 129 0 0 Pass 0.6537 119 0 0 Pass 0.6603 109 0 0 Pass 0.6670 97 0 0 Pass 0.6736 92 0 0 Pass 0.6802 82 0 0 Pass 0.6869 78 0 0 Pass 0.6935 69 0 0 Pass 0.7002 61 0 0 Pass 0.7068 55 0 0 Pass 0.7135 48 0 0 Pass 0.7201 41 0 0 Pass 0.7267 38 0 0 Pass 0.7334 33 0 0 Pass 0.7400 27 0 0 Pass 0.7467 23 0 0 Pass 0.7533 21 0 0 Pass 0.7600 20 0 0 Pass 0.7666 19 0 0 Pass 0.7732 17 0 0 Pass 0.7799 14 0 0 Pass 0.7865 12 0 0 Pass 0.7932 9 0 0 Pass 0.7998 4 0 0 Pass 0.8065 3 0 0 Pass 0.8131 3 0 0 Pass 0.8197 3 0 0 Pass 0.8264 3 0 0 Pass Pond 1 10/24/2017 4:09:34 PM Page 18 Appendix Predeveloped Schematic Pond 1 10/24/2017 4:09:34 PM Page 19 Mitigated Schematic Pond 1 10/24/2017 4:19:51 PM Page 5 Mitigated Land Use Basin 1 Without Roof Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.91 Pervious Total 1.91 Impervious Land Use acre ROADS FLAT 1.82 SIDEWALKS FLAT 0.2 Impervious Total 2.02 Basin Total 3.93 Element Flows To: Surface Interflow Groundwater Water Quality Node Water Quality Node Pond 1 10/24/2017 4:21:20 PM Page 27 Water Quality Water Quality BMP Flow and Volume for POC #2 On-line facility volume:0.3052 acre-feet On-line facility target flow:0.3247 cfs. Adjusted for 15 min:0.3247 cfs. Off-line facility target flow:0.1807 cfs. Adjusted for 15 min:0.1807 cfs. Pond 2 10/24/2017 5:15:39 PM Page 2 General Model Information Project Name:Pond 2 Site Name: Site Address: City: Report Date:10/24/2017 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 Pond 2 10/24/2017 5:15:39 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 2 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 44.33 Pervious Total 44.33 Impervious Land Use acre Impervious Total 0 Basin Total 44.33 Element Flows To: Surface Interflow Groundwater Pond 2 10/24/2017 5:15:39 PM Page 4 Mitigated Land Use Basin 2 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 7.5 Pervious Total 7.5 Impervious Land Use acre ROADS FLAT 21.54 ROOF TOPS FLAT 13.13 SIDEWALKS FLAT 1.63 POND 0.14 Impervious Total 36.44 Basin Total 43.94 Element Flows To: Surface Interflow Groundwater Pond 2 Pond 2 Pond 2 10/24/2017 5:15:39 PM Page 5 Basin 2 Bypass Bypass:Yes GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.02 Pervious Total 0.02 Impervious Land Use acre ROADS FLAT 0.37 Impervious Total 0.37 Basin Total 0.39 Element Flows To: Surface Interflow Groundwater Pond 2 10/24/2017 5:15:39 PM Page 7 Mitigated Routing Pond 2 Bottom Length:310.00 ft. Bottom Width:350.00 ft. Depth:8 ft. Volume at riser head:19.0278 acre-feet. Side slope 1:2 To 1 Side slope 2:2 To 1 Side slope 3:2 To 1 Side slope 4:2 To 1 Discharge Structure Riser Height:7 ft. Riser Diameter:18 in. Orifice 1 Diameter:3.25 in.Elevation:0 ft. Orifice 2 Diameter:3.75 in.Elevation:4.5 ft. Orifice 3 Diameter:4.25 in.Elevation:6.625 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 2.490 0.000 0.000 0.000 0.0889 2.496 0.221 0.085 0.000 0.1778 2.501 0.443 0.120 0.000 0.2667 2.507 0.666 0.148 0.000 0.3556 2.512 0.889 0.170 0.000 0.4444 2.517 1.113 0.191 0.000 0.5333 2.523 1.337 0.209 0.000 0.6222 2.528 1.561 0.226 0.000 0.7111 2.534 1.786 0.241 0.000 0.8000 2.539 2.012 0.256 0.000 0.8889 2.545 2.238 0.270 0.000 0.9778 2.550 2.464 0.283 0.000 1.0667 2.555 2.691 0.296 0.000 1.1556 2.561 2.918 0.308 0.000 1.2444 2.566 3.146 0.319 0.000 1.3333 2.572 3.375 0.331 0.000 1.4222 2.577 3.604 0.341 0.000 1.5111 2.583 3.833 0.352 0.000 1.6000 2.588 4.063 0.362 0.000 1.6889 2.594 4.293 0.372 0.000 1.7778 2.599 4.524 0.382 0.000 1.8667 2.605 4.755 0.391 0.000 1.9556 2.610 4.987 0.400 0.000 2.0444 2.616 5.220 0.409 0.000 2.1333 2.621 5.452 0.418 0.000 2.2222 2.627 5.686 0.427 0.000 2.3111 2.632 5.919 0.435 0.000 2.4000 2.638 6.154 0.444 0.000 2.4889 2.643 6.389 0.452 0.000 2.5778 2.649 6.624 0.460 0.000 2.6667 2.655 6.860 0.468 0.000 2.7556 2.660 7.096 0.475 0.000 2.8444 2.666 7.333 0.483 0.000 Pond 2 10/24/2017 5:15:39 PM Page 8 2.9333 2.671 7.570 0.490 0.000 3.0222 2.677 7.808 0.498 0.000 3.1111 2.682 8.046 0.505 0.000 3.2000 2.688 8.284 0.512 0.000 3.2889 2.694 8.524 0.519 0.000 3.3778 2.699 8.763 0.526 0.000 3.4667 2.705 9.004 0.533 0.000 3.5556 2.710 9.244 0.540 0.000 3.6444 2.716 9.486 0.547 0.000 3.7333 2.722 9.727 0.553 0.000 3.8222 2.727 9.970 0.560 0.000 3.9111 2.733 10.21 0.566 0.000 4.0000 2.739 10.45 0.573 0.000 4.0889 2.744 10.70 0.579 0.000 4.1778 2.750 10.94 0.585 0.000 4.2667 2.756 11.18 0.592 0.000 4.3556 2.761 11.43 0.598 0.000 4.4444 2.767 11.68 0.604 0.000 4.5333 2.773 11.92 0.680 0.000 4.6222 2.778 12.17 0.749 0.000 4.7111 2.784 12.42 0.797 0.000 4.8000 2.790 12.66 0.837 0.000 4.8889 2.795 12.91 0.871 0.000 4.9778 2.801 13.16 0.903 0.000 5.0667 2.807 13.41 0.932 0.000 5.1556 2.813 13.66 0.959 0.000 5.2444 2.818 13.91 0.985 0.000 5.3333 2.824 14.16 1.010 0.000 5.4222 2.830 14.41 1.033 0.000 5.5111 2.836 14.66 1.056 0.000 5.6000 2.841 14.92 1.078 0.000 5.6889 2.847 15.17 1.099 0.000 5.7778 2.853 15.42 1.120 0.000 5.8667 2.859 15.68 1.140 0.000 5.9556 2.864 15.93 1.159 0.000 6.0444 2.870 16.19 1.178 0.000 6.1333 2.876 16.44 1.197 0.000 6.2222 2.882 16.70 1.215 0.000 6.3111 2.887 16.95 1.233 0.000 6.4000 2.893 17.21 1.251 0.000 6.4889 2.899 17.47 1.268 0.000 6.5778 2.905 17.73 1.285 0.000 6.6667 2.911 17.98 1.401 0.000 6.7556 2.917 18.24 1.495 0.000 6.8444 2.922 18.50 1.563 0.000 6.9333 2.928 18.76 1.622 0.000 7.0222 2.934 19.02 1.727 0.000 7.1111 2.940 19.28 2.310 0.000 7.2000 2.946 19.55 3.172 0.000 7.2889 2.952 19.81 4.185 0.000 7.3778 2.957 20.07 5.237 0.000 7.4667 2.963 20.33 6.216 0.000 7.5556 2.969 20.60 7.025 0.000 7.6444 2.975 20.86 7.613 0.000 7.7333 2.981 21.13 8.013 0.000 7.8222 2.987 21.39 8.459 0.000 7.9111 2.993 21.66 8.831 0.000 8.0000 2.999 21.92 9.186 0.000 Pond 2 10/24/2017 5:15:39 PM Page 9 8.0889 3.005 22.19 9.526 0.000 Pond 2 10/24/2017 5:15:39 PM Page 10 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:44.33 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:7.52 Total Impervious Area:36.81 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.303339 5 year 2.046945 10 year 2.468359 25 year 2.91481 50 year 3.191076 100 year 3.426052 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.71474 5 year 0.980593 10 year 1.1771 25 year 1.449717 50 year 1.671145 100 year 1.908881 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.280 0.542 1950 1.596 0.708 1951 2.870 1.322 1952 0.904 0.504 1953 0.731 0.811 1954 1.123 0.572 1955 1.791 0.593 1956 1.425 1.097 1957 1.150 0.571 1958 1.296 0.606 Pond 2 10/24/2017 5:16:09 PM Page 11 1959 1.112 0.592 1960 1.941 1.094 1961 1.095 0.829 1962 0.681 0.488 1963 0.935 0.627 1964 1.231 0.861 1965 0.881 0.933 1966 0.847 0.602 1967 1.772 0.708 1968 1.105 0.595 1969 1.082 0.578 1970 0.892 0.612 1971 0.954 0.626 1972 2.137 1.222 1973 0.971 0.939 1974 1.054 0.615 1975 1.428 0.599 1976 1.032 0.565 1977 0.123 0.544 1978 0.906 0.652 1979 0.547 0.442 1980 2.026 1.244 1981 0.810 0.582 1982 1.557 1.088 1983 1.396 0.587 1984 0.862 0.525 1985 0.511 0.527 1986 2.259 0.656 1987 1.998 1.046 1988 0.789 0.585 1989 0.514 0.525 1990 4.178 1.106 1991 2.516 1.207 1992 0.970 0.623 1993 1.011 0.479 1994 0.340 0.457 1995 1.449 0.843 1996 3.054 1.278 1997 2.553 1.509 1998 0.577 0.539 1999 2.394 1.226 2000 1.008 0.611 2001 0.181 0.493 2002 1.104 0.722 2003 1.409 0.571 2004 1.824 1.248 2005 1.309 0.571 2006 1.543 1.090 2007 3.101 1.933 2008 4.000 1.198 2009 1.964 0.874 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 4.1779 1.9330 2 4.0004 1.5089 3 3.1012 1.3216 Pond 2 10/24/2017 5:16:09 PM Page 12 4 3.0539 1.2781 5 2.8701 1.2481 6 2.5529 1.2444 7 2.5156 1.2260 8 2.3940 1.2215 9 2.2590 1.2066 10 2.1373 1.1983 11 2.0255 1.1064 12 1.9982 1.0968 13 1.9642 1.0935 14 1.9406 1.0896 15 1.8241 1.0877 16 1.7912 1.0464 17 1.7722 0.9391 18 1.5964 0.9333 19 1.5569 0.8743 20 1.5432 0.8607 21 1.4490 0.8425 22 1.4278 0.8288 23 1.4253 0.8108 24 1.4088 0.7215 25 1.3959 0.7084 26 1.3086 0.7079 27 1.2958 0.6565 28 1.2803 0.6521 29 1.2311 0.6271 30 1.1502 0.6262 31 1.1233 0.6226 32 1.1115 0.6151 33 1.1055 0.6120 34 1.1043 0.6106 35 1.0948 0.6060 36 1.0815 0.6025 37 1.0538 0.5995 38 1.0322 0.5947 39 1.0105 0.5926 40 1.0077 0.5921 41 0.9709 0.5875 42 0.9702 0.5854 43 0.9538 0.5820 44 0.9352 0.5784 45 0.9057 0.5716 46 0.9044 0.5711 47 0.8918 0.5709 48 0.8815 0.5706 49 0.8617 0.5650 50 0.8475 0.5438 51 0.8095 0.5424 52 0.7885 0.5395 53 0.7315 0.5271 54 0.6812 0.5254 55 0.5775 0.5253 56 0.5472 0.5038 57 0.5145 0.4933 58 0.5113 0.4875 59 0.3396 0.4793 60 0.1807 0.4566 61 0.1229 0.4424 Pond 2 10/24/2017 5:16:09 PM Page 14 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.6517 17603 11400 64 Pass 0.6773 16174 10684 66 Pass 0.7030 15002 10162 67 Pass 0.7286 13873 9657 69 Pass 0.7543 12818 9165 71 Pass 0.7799 11845 8590 72 Pass 0.8056 10910 7884 72 Pass 0.8312 10121 7261 71 Pass 0.8569 9407 6611 70 Pass 0.8825 8746 6042 69 Pass 0.9082 8147 5495 67 Pass 0.9338 7612 5084 66 Pass 0.9595 7071 4601 65 Pass 0.9851 6590 4117 62 Pass 1.0108 6158 3643 59 Pass 1.0364 5781 3221 55 Pass 1.0621 5431 2870 52 Pass 1.0877 5108 2481 48 Pass 1.1134 4808 2180 45 Pass 1.1390 4522 1839 40 Pass 1.1647 4259 1447 33 Pass 1.1903 4017 1120 27 Pass 1.2160 3794 816 21 Pass 1.2416 3551 504 14 Pass 1.2673 3339 356 10 Pass 1.2929 3140 257 8 Pass 1.3186 2954 219 7 Pass 1.3442 2787 200 7 Pass 1.3699 2603 186 7 Pass 1.3955 2449 172 7 Pass 1.4212 2304 163 7 Pass 1.4468 2162 154 7 Pass 1.4725 2027 145 7 Pass 1.4981 1898 137 7 Pass 1.5238 1790 125 6 Pass 1.5494 1689 121 7 Pass 1.5751 1585 116 7 Pass 1.6007 1483 111 7 Pass 1.6264 1381 105 7 Pass 1.6520 1292 97 7 Pass 1.6777 1222 84 6 Pass 1.7033 1155 47 4 Pass 1.7290 1098 26 2 Pass 1.7546 1049 13 1 Pass 1.7803 997 12 1 Pass 1.8059 930 11 1 Pass 1.8316 884 9 1 Pass 1.8572 837 8 0 Pass 1.8829 790 6 0 Pass 1.9085 743 4 0 Pass 1.9342 713 0 0 Pass 1.9598 670 0 0 Pass 1.9855 632 0 0 Pass Pond 2 10/24/2017 5:16:09 PM Page 15 2.0111 595 0 0 Pass 2.0368 567 0 0 Pass 2.0625 539 0 0 Pass 2.0881 496 0 0 Pass 2.1138 473 0 0 Pass 2.1394 434 0 0 Pass 2.1651 399 0 0 Pass 2.1907 369 0 0 Pass 2.2164 348 0 0 Pass 2.2420 323 0 0 Pass 2.2677 296 0 0 Pass 2.2933 272 0 0 Pass 2.3190 256 0 0 Pass 2.3446 235 0 0 Pass 2.3703 217 0 0 Pass 2.3959 198 0 0 Pass 2.4216 180 0 0 Pass 2.4472 158 0 0 Pass 2.4729 145 0 0 Pass 2.4985 129 0 0 Pass 2.5242 119 0 0 Pass 2.5498 109 0 0 Pass 2.5755 97 0 0 Pass 2.6011 91 0 0 Pass 2.6268 82 0 0 Pass 2.6524 76 0 0 Pass 2.6781 68 0 0 Pass 2.7037 61 0 0 Pass 2.7294 54 0 0 Pass 2.7550 48 0 0 Pass 2.7807 41 0 0 Pass 2.8063 38 0 0 Pass 2.8320 33 0 0 Pass 2.8576 27 0 0 Pass 2.8833 22 0 0 Pass 2.9089 21 0 0 Pass 2.9346 20 0 0 Pass 2.9602 19 0 0 Pass 2.9859 17 0 0 Pass 3.0115 14 0 0 Pass 3.0372 12 0 0 Pass 3.0628 9 0 0 Pass 3.0885 4 0 0 Pass 3.1141 3 0 0 Pass 3.1398 3 0 0 Pass 3.1654 3 0 0 Pass 3.1911 3 0 0 Pass Pond 2 10/24/2017 5:16:18 PM Page 19 Appendix Predeveloped Schematic Pond 2 10/24/2017 5:16:18 PM Page 20 Mitigated Schematic Pond 3 10/24/2017 5:00:20 PM Page 2 General Model Information Project Name:Pond 3 Site Name: Site Address: City: Report Date:10/24/2017 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 Pond 3 10/24/2017 5:00:20 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 3 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 4.96 Pervious Total 4.96 Impervious Land Use acre Impervious Total 0 Basin Total 4.96 Element Flows To: Surface Interflow Groundwater Pond 3 10/24/2017 5:00:20 PM Page 4 Mitigated Land Use Basin 3 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.51 Pervious Total 1.51 Impervious Land Use acre ROOF TOPS FLAT 3.31 POND 0.14 Impervious Total 3.45 Basin Total 4.96 Element Flows To: Surface Interflow Groundwater Pond 3 Pond 3 Pond 3 10/24/2017 5:00:20 PM Page 6 Mitigated Routing Pond 3 Bottom Length:185.00 ft. Bottom Width:185.00 ft. Depth:3 ft. Volume at riser head:1.7112 acre-feet. Side slope 1:4 To 1 Side slope 2:4 To 1 Side slope 3:4 To 1 Side slope 4:4 To 1 Discharge Structure Riser Height:2 ft. Riser Diameter:18 in. Orifice 1 Diameter:1.58 in.Elevation:0 ft. Orifice 2 Diameter:1.45 in.Elevation:1.13 ft. Orifice 3 Diameter:2.14 in.Elevation:1.33 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.785 0.000 0.000 0.000 0.0333 0.788 0.026 0.012 0.000 0.0667 0.790 0.052 0.017 0.000 0.1000 0.792 0.078 0.021 0.000 0.1333 0.794 0.105 0.024 0.000 0.1667 0.797 0.131 0.027 0.000 0.2000 0.799 0.158 0.030 0.000 0.2333 0.801 0.185 0.032 0.000 0.2667 0.803 0.211 0.035 0.000 0.3000 0.806 0.238 0.037 0.000 0.3333 0.808 0.265 0.039 0.000 0.3667 0.810 0.292 0.041 0.000 0.4000 0.813 0.319 0.042 0.000 0.4333 0.815 0.346 0.044 0.000 0.4667 0.817 0.374 0.046 0.000 0.5000 0.820 0.401 0.047 0.000 0.5333 0.822 0.428 0.049 0.000 0.5667 0.824 0.456 0.051 0.000 0.6000 0.827 0.483 0.052 0.000 0.6333 0.829 0.511 0.053 0.000 0.6667 0.831 0.539 0.055 0.000 0.7000 0.834 0.566 0.056 0.000 0.7333 0.836 0.594 0.058 0.000 0.7667 0.838 0.622 0.059 0.000 0.8000 0.841 0.650 0.060 0.000 0.8333 0.843 0.678 0.061 0.000 0.8667 0.845 0.706 0.063 0.000 0.9000 0.848 0.735 0.064 0.000 0.9333 0.850 0.763 0.065 0.000 0.9667 0.852 0.791 0.066 0.000 1.0000 0.855 0.820 0.067 0.000 1.0333 0.857 0.848 0.068 0.000 1.0667 0.859 0.877 0.070 0.000 Pond 3 10/24/2017 5:00:20 PM Page 7 1.1000 0.862 0.906 0.071 0.000 1.1333 0.864 0.934 0.075 0.000 1.1667 0.867 0.963 0.084 0.000 1.2000 0.869 0.992 0.089 0.000 1.2333 0.871 1.021 0.093 0.000 1.2667 0.874 1.050 0.097 0.000 1.3000 0.876 1.079 0.100 0.000 1.3333 0.878 1.109 0.111 0.000 1.3667 0.881 1.138 0.130 0.000 1.4000 0.883 1.167 0.142 0.000 1.4333 0.886 1.197 0.152 0.000 1.4667 0.888 1.227 0.161 0.000 1.5000 0.890 1.256 0.168 0.000 1.5333 0.893 1.286 0.176 0.000 1.5667 0.895 1.316 0.183 0.000 1.6000 0.898 1.346 0.189 0.000 1.6333 0.900 1.376 0.195 0.000 1.6667 0.903 1.406 0.201 0.000 1.7000 0.905 1.436 0.207 0.000 1.7333 0.907 1.466 0.212 0.000 1.7667 0.910 1.496 0.217 0.000 1.8000 0.912 1.527 0.222 0.000 1.8333 0.915 1.557 0.227 0.000 1.8667 0.917 1.588 0.232 0.000 1.9000 0.920 1.618 0.237 0.000 1.9333 0.922 1.649 0.241 0.000 1.9667 0.925 1.680 0.246 0.000 2.0000 0.927 1.711 0.250 0.000 2.0333 0.929 1.742 0.351 0.000 2.0667 0.932 1.773 0.533 0.000 2.1000 0.934 1.804 0.765 0.000 2.1333 0.937 1.835 1.038 0.000 2.1667 0.939 1.866 1.345 0.000 2.2000 0.942 1.898 1.679 0.000 2.2333 0.944 1.929 2.035 0.000 2.2667 0.947 1.961 2.406 0.000 2.3000 0.949 1.992 2.788 0.000 2.3333 0.952 2.024 3.173 0.000 2.3667 0.954 2.056 3.555 0.000 2.4000 0.957 2.088 3.930 0.000 2.4333 0.959 2.120 4.290 0.000 2.4667 0.962 2.152 4.630 0.000 2.5000 0.964 2.184 4.947 0.000 2.5333 0.967 2.216 5.235 0.000 2.5667 0.969 2.248 5.493 0.000 2.6000 0.972 2.281 5.719 0.000 2.6333 0.974 2.313 5.914 0.000 2.6667 0.977 2.346 6.079 0.000 2.7000 0.979 2.378 6.220 0.000 2.7333 0.982 2.411 6.345 0.000 2.7667 0.984 2.444 6.539 0.000 2.8000 0.987 2.477 6.676 0.000 2.8333 0.990 2.510 6.810 0.000 2.8667 0.992 2.543 6.941 0.000 2.9000 0.995 2.576 7.070 0.000 2.9333 0.997 2.609 7.196 0.000 2.9667 1.000 2.642 7.320 0.000 3.0000 1.002 2.676 7.442 0.000 Pond 3 10/24/2017 5:00:20 PM Page 8 3.0333 1.005 2.709 7.562 0.000 Pond 3 10/24/2017 5:00:20 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:4.96 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:1.51 Total Impervious Area:3.45 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.145828 5 year 0.229029 10 year 0.27618 25 year 0.326133 50 year 0.357043 100 year 0.383335 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.092665 5 year 0.143907 10 year 0.185566 25 year 0.247985 50 year 0.302238 100 year 0.363709 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.143 0.063 1950 0.179 0.094 1951 0.321 0.224 1952 0.101 0.057 1953 0.082 0.076 1954 0.126 0.068 1955 0.200 0.067 1956 0.159 0.152 1957 0.129 0.068 1958 0.145 0.084 Pond 3 10/24/2017 5:00:50 PM Page 10 1959 0.124 0.063 1960 0.217 0.195 1961 0.122 0.107 1962 0.076 0.057 1963 0.105 0.072 1964 0.138 0.095 1965 0.099 0.139 1966 0.095 0.069 1967 0.198 0.090 1968 0.124 0.069 1969 0.121 0.068 1970 0.100 0.077 1971 0.107 0.075 1972 0.239 0.192 1973 0.109 0.131 1974 0.118 0.074 1975 0.160 0.065 1976 0.115 0.070 1977 0.014 0.059 1978 0.101 0.092 1979 0.061 0.053 1980 0.227 0.200 1981 0.091 0.070 1982 0.174 0.166 1983 0.156 0.073 1984 0.096 0.058 1985 0.057 0.061 1986 0.253 0.098 1987 0.224 0.181 1988 0.088 0.064 1989 0.058 0.061 1990 0.467 0.201 1991 0.281 0.185 1992 0.109 0.093 1993 0.113 0.058 1994 0.038 0.052 1995 0.162 0.102 1996 0.342 0.218 1997 0.286 0.218 1998 0.065 0.058 1999 0.268 0.192 2000 0.113 0.092 2001 0.020 0.049 2002 0.124 0.114 2003 0.158 0.067 2004 0.204 0.220 2005 0.146 0.069 2006 0.173 0.152 2007 0.347 0.315 2008 0.448 0.212 2009 0.220 0.138 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.4675 0.3149 2 0.4476 0.2237 3 0.3470 0.2201 Pond 3 10/24/2017 5:00:50 PM Page 11 4 0.3417 0.2182 5 0.3211 0.2181 6 0.2856 0.2116 7 0.2815 0.2005 8 0.2679 0.2003 9 0.2528 0.1947 10 0.2391 0.1922 11 0.2266 0.1919 12 0.2236 0.1847 13 0.2198 0.1814 14 0.2171 0.1663 15 0.2041 0.1525 16 0.2004 0.1523 17 0.1983 0.1391 18 0.1786 0.1375 19 0.1742 0.1310 20 0.1727 0.1136 21 0.1621 0.1066 22 0.1598 0.1021 23 0.1595 0.0982 24 0.1576 0.0953 25 0.1562 0.0938 26 0.1464 0.0930 27 0.1450 0.0923 28 0.1432 0.0916 29 0.1377 0.0902 30 0.1287 0.0835 31 0.1257 0.0770 32 0.1244 0.0764 33 0.1237 0.0748 34 0.1236 0.0740 35 0.1225 0.0725 36 0.1210 0.0719 37 0.1179 0.0704 38 0.1155 0.0696 39 0.1131 0.0690 40 0.1128 0.0690 41 0.1086 0.0687 42 0.1086 0.0685 43 0.1067 0.0685 44 0.1046 0.0675 45 0.1013 0.0674 46 0.1012 0.0667 47 0.0998 0.0649 48 0.0986 0.0642 49 0.0964 0.0634 50 0.0948 0.0633 51 0.0906 0.0615 52 0.0882 0.0606 53 0.0818 0.0586 54 0.0762 0.0584 55 0.0646 0.0584 56 0.0612 0.0580 57 0.0576 0.0572 58 0.0572 0.0572 59 0.0380 0.0534 60 0.0202 0.0521 61 0.0137 0.0488 Pond 3 10/24/2017 5:00:50 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0729 17550 14775 84 Pass 0.0758 16164 13327 82 Pass 0.0787 14964 12592 84 Pass 0.0815 13851 11914 86 Pass 0.0844 12810 11248 87 Pass 0.0873 11809 10230 86 Pass 0.0901 10898 9210 84 Pass 0.0930 10119 8241 81 Pass 0.0959 9383 7401 78 Pass 0.0987 8729 6370 72 Pass 0.1016 8147 5452 66 Pass 0.1045 7610 5118 67 Pass 0.1074 7071 4823 68 Pass 0.1102 6590 4519 68 Pass 0.1131 6160 4336 70 Pass 0.1160 5784 4220 72 Pass 0.1188 5435 4087 75 Pass 0.1217 5097 3972 77 Pass 0.1246 4815 3850 79 Pass 0.1274 4528 3715 82 Pass 0.1303 4252 3625 85 Pass 0.1332 4021 3499 87 Pass 0.1361 3784 3377 89 Pass 0.1389 3548 3255 91 Pass 0.1418 3341 3155 94 Pass 0.1447 3138 3027 96 Pass 0.1475 2954 2896 98 Pass 0.1504 2785 2770 99 Pass 0.1533 2599 2614 100 Pass 0.1561 2449 2479 101 Pass 0.1590 2304 2370 102 Pass 0.1619 2162 2239 103 Pass 0.1648 2027 2113 104 Pass 0.1676 1898 1986 104 Pass 0.1705 1790 1854 103 Pass 0.1734 1689 1701 100 Pass 0.1762 1587 1586 99 Pass 0.1791 1483 1465 98 Pass 0.1820 1382 1330 96 Pass 0.1848 1292 1195 92 Pass 0.1877 1218 1098 90 Pass 0.1906 1155 984 85 Pass 0.1935 1098 884 80 Pass 0.1963 1048 794 75 Pass 0.1992 997 706 70 Pass 0.2021 930 591 63 Pass 0.2049 883 507 57 Pass 0.2078 837 427 51 Pass 0.2107 789 362 45 Pass 0.2135 743 304 40 Pass 0.2164 713 253 35 Pass 0.2193 670 186 27 Pass 0.2222 631 157 24 Pass Pond 3 10/24/2017 5:00:50 PM Page 14 0.2250 596 137 22 Pass 0.2279 567 132 23 Pass 0.2308 539 126 23 Pass 0.2336 497 119 23 Pass 0.2365 473 114 24 Pass 0.2394 435 107 24 Pass 0.2422 399 95 23 Pass 0.2451 366 61 16 Pass 0.2480 348 46 13 Pass 0.2509 323 34 10 Pass 0.2537 296 32 10 Pass 0.2566 273 32 11 Pass 0.2595 256 32 12 Pass 0.2623 235 31 13 Pass 0.2652 217 31 14 Pass 0.2681 197 29 14 Pass 0.2709 180 29 16 Pass 0.2738 158 27 17 Pass 0.2767 145 25 17 Pass 0.2796 129 23 17 Pass 0.2824 119 20 16 Pass 0.2853 109 15 13 Pass 0.2882 97 14 14 Pass 0.2910 91 12 13 Pass 0.2939 82 12 14 Pass 0.2968 76 10 13 Pass 0.2996 69 10 14 Pass 0.3025 61 9 14 Pass 0.3054 54 8 14 Pass 0.3083 48 7 14 Pass 0.3111 41 5 12 Pass 0.3140 38 3 7 Pass 0.3169 33 0 0 Pass 0.3197 27 0 0 Pass 0.3226 22 0 0 Pass 0.3255 21 0 0 Pass 0.3283 20 0 0 Pass 0.3312 19 0 0 Pass 0.3341 17 0 0 Pass 0.3370 14 0 0 Pass 0.3398 12 0 0 Pass 0.3427 9 0 0 Pass 0.3456 4 0 0 Pass 0.3484 3 0 0 Pass 0.3513 3 0 0 Pass 0.3542 3 0 0 Pass 0.3570 3 0 0 Pass Pond 3 10/24/2017 5:00:59 PM Page 18 Appendix Predeveloped Schematic Pond 3 10/24/2017 5:00:59 PM Page 19 Mitigated Schematic Pond 4 10/24/2017 5:10:01 PM Page 2 General Model Information Project Name:Pond 4 Site Name: Site Address: City: Report Date:10/24/2017 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 Pond 4 10/24/2017 5:10:01 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 4 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 5.82 Pervious Total 5.82 Impervious Land Use acre Impervious Total 0 Basin Total 5.82 Element Flows To: Surface Interflow Groundwater Pond 4 10/24/2017 5:10:01 PM Page 4 Mitigated Land Use Basin 4 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.26 Pervious Total 1.26 Impervious Land Use acre ROADS FLAT 4.12 SIDEWALKS FLAT 0.39 POND 0.05 Impervious Total 4.56 Basin Total 5.82 Element Flows To: Surface Interflow Groundwater Pond 4 Pond 4 Pond 4 10/24/2017 5:10:01 PM Page 6 Mitigated Routing Pond 4 Bottom Length:75.00 ft. Bottom Width:75.00 ft. Depth:12 ft. Volume at riser head:2.4385 acre-feet. Side slope 1:2 To 1 Side slope 2:2 To 1 Side slope 3:2 To 1 Side slope 4:2 To 1 Discharge Structure Riser Height:11 ft. Riser Diameter:18 in. Orifice 1 Diameter:1.1 in.Elevation:0 ft. Orifice 2 Diameter:0.75 in.Elevation:7 ft. Orifice 3 Diameter:2 in.Elevation:7.75 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.129 0.000 0.000 0.000 0.1333 0.131 0.017 0.012 0.000 0.2667 0.132 0.034 0.017 0.000 0.4000 0.134 0.052 0.020 0.000 0.5333 0.136 0.070 0.024 0.000 0.6667 0.138 0.089 0.026 0.000 0.8000 0.140 0.107 0.029 0.000 0.9333 0.142 0.126 0.031 0.000 1.0667 0.144 0.145 0.033 0.000 1.2000 0.146 0.165 0.036 0.000 1.3333 0.148 0.184 0.037 0.000 1.4667 0.150 0.204 0.039 0.000 1.6000 0.152 0.224 0.041 0.000 1.7333 0.154 0.245 0.043 0.000 1.8667 0.156 0.265 0.044 0.000 2.0000 0.158 0.286 0.046 0.000 2.1333 0.160 0.308 0.048 0.000 2.2667 0.162 0.329 0.049 0.000 2.4000 0.164 0.351 0.050 0.000 2.5333 0.166 0.373 0.052 0.000 2.6667 0.168 0.395 0.053 0.000 2.8000 0.170 0.418 0.054 0.000 2.9333 0.172 0.441 0.056 0.000 3.0667 0.174 0.464 0.057 0.000 3.2000 0.177 0.487 0.058 0.000 3.3333 0.179 0.511 0.059 0.000 3.4667 0.181 0.535 0.061 0.000 3.6000 0.183 0.559 0.062 0.000 3.7333 0.185 0.584 0.063 0.000 3.8667 0.187 0.609 0.064 0.000 4.0000 0.190 0.634 0.065 0.000 4.1333 0.192 0.660 0.066 0.000 4.2667 0.194 0.685 0.067 0.000 Pond 4 10/24/2017 5:10:01 PM Page 7 4.4000 0.196 0.711 0.068 0.000 4.5333 0.199 0.738 0.069 0.000 4.6667 0.201 0.765 0.070 0.000 4.8000 0.203 0.792 0.071 0.000 4.9333 0.206 0.819 0.072 0.000 5.0667 0.208 0.847 0.073 0.000 5.2000 0.210 0.874 0.074 0.000 5.3333 0.213 0.903 0.075 0.000 5.4667 0.215 0.931 0.076 0.000 5.6000 0.217 0.960 0.077 0.000 5.7333 0.220 0.989 0.078 0.000 5.8667 0.222 1.019 0.079 0.000 6.0000 0.225 1.049 0.080 0.000 6.1333 0.227 1.079 0.081 0.000 6.2667 0.229 1.109 0.082 0.000 6.4000 0.232 1.140 0.083 0.000 6.5333 0.234 1.171 0.083 0.000 6.6667 0.237 1.203 0.084 0.000 6.8000 0.239 1.235 0.085 0.000 6.9333 0.242 1.267 0.086 0.000 7.0667 0.244 1.299 0.091 0.000 7.2000 0.247 1.332 0.094 0.000 7.3333 0.249 1.365 0.097 0.000 7.4667 0.252 1.399 0.100 0.000 7.6000 0.255 1.433 0.102 0.000 7.7333 0.257 1.467 0.104 0.000 7.8667 0.260 1.501 0.143 0.000 8.0000 0.262 1.536 0.162 0.000 8.1333 0.265 1.571 0.177 0.000 8.2667 0.268 1.607 0.189 0.000 8.4000 0.270 1.643 0.200 0.000 8.5333 0.273 1.679 0.210 0.000 8.6667 0.276 1.716 0.220 0.000 8.8000 0.278 1.753 0.229 0.000 8.9333 0.281 1.790 0.237 0.000 9.0667 0.284 1.828 0.245 0.000 9.2000 0.286 1.866 0.252 0.000 9.3333 0.289 1.904 0.260 0.000 9.4667 0.292 1.943 0.267 0.000 9.6000 0.295 1.982 0.274 0.000 9.7333 0.298 2.022 0.280 0.000 9.8667 0.300 2.062 0.286 0.000 10.000 0.303 2.102 0.293 0.000 10.133 0.306 2.143 0.299 0.000 10.267 0.309 2.184 0.305 0.000 10.400 0.312 2.225 0.310 0.000 10.533 0.315 2.267 0.316 0.000 10.667 0.317 2.309 0.321 0.000 10.800 0.320 2.352 0.327 0.000 10.933 0.323 2.395 0.332 0.000 11.067 0.326 2.438 0.611 0.000 11.200 0.329 2.482 1.747 0.000 11.333 0.332 2.526 3.230 0.000 11.467 0.335 2.570 4.678 0.000 11.600 0.338 2.615 5.758 0.000 11.733 0.341 2.661 6.376 0.000 11.867 0.344 2.706 6.964 0.000 12.000 0.347 2.752 7.458 0.000 Pond 4 10/24/2017 5:10:01 PM Page 8 12.133 0.350 2.799 7.920 0.000 Pond 4 10/24/2017 5:10:01 PM Page 9 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:5.82 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:1.26 Total Impervious Area:4.56 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.171113 5 year 0.268739 10 year 0.324066 25 year 0.38268 50 year 0.41895 100 year 0.4498 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.103586 5 year 0.16094 10 year 0.20858 25 year 0.281333 50 year 0.345702 100 year 0.419723 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.168 0.075 1950 0.210 0.086 1951 0.377 0.266 1952 0.119 0.068 1953 0.096 0.085 1954 0.147 0.080 1955 0.235 0.079 1956 0.187 0.183 1957 0.151 0.080 1958 0.170 0.085 Pond 4 10/24/2017 5:10:30 PM Page 10 1959 0.146 0.075 1960 0.255 0.229 1961 0.144 0.100 1962 0.089 0.069 1963 0.123 0.083 1964 0.162 0.094 1965 0.116 0.151 1966 0.111 0.081 1967 0.233 0.086 1968 0.145 0.081 1969 0.142 0.079 1970 0.117 0.084 1971 0.125 0.084 1972 0.281 0.239 1973 0.127 0.152 1974 0.138 0.083 1975 0.187 0.077 1976 0.136 0.081 1977 0.016 0.072 1978 0.119 0.087 1979 0.072 0.065 1980 0.266 0.248 1981 0.106 0.082 1982 0.204 0.183 1983 0.183 0.083 1984 0.113 0.070 1985 0.067 0.074 1986 0.297 0.096 1987 0.262 0.209 1988 0.104 0.077 1989 0.068 0.073 1990 0.549 0.230 1991 0.330 0.223 1992 0.127 0.091 1993 0.133 0.070 1994 0.045 0.064 1995 0.190 0.099 1996 0.401 0.259 1997 0.335 0.264 1998 0.076 0.071 1999 0.314 0.226 2000 0.132 0.091 2001 0.024 0.062 2002 0.145 0.102 2003 0.185 0.080 2004 0.239 0.267 2005 0.172 0.081 2006 0.203 0.185 2007 0.407 0.312 2008 0.525 0.252 2009 0.258 0.104 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.5485 0.3125 2 0.5252 0.2674 3 0.4071 0.2660 Pond 4 10/24/2017 5:10:30 PM Page 11 4 0.4009 0.2639 5 0.3768 0.2595 6 0.3352 0.2515 7 0.3303 0.2477 8 0.3143 0.2393 9 0.2966 0.2301 10 0.2806 0.2289 11 0.2659 0.2261 12 0.2623 0.2230 13 0.2579 0.2086 14 0.2548 0.1853 15 0.2395 0.1832 16 0.2352 0.1830 17 0.2327 0.1525 18 0.2096 0.1512 19 0.2044 0.1042 20 0.2026 0.1024 21 0.1902 0.0998 22 0.1875 0.0990 23 0.1871 0.0961 24 0.1850 0.0943 25 0.1833 0.0913 26 0.1718 0.0910 27 0.1701 0.0867 28 0.1681 0.0864 29 0.1616 0.0863 30 0.1510 0.0852 31 0.1475 0.0845 32 0.1459 0.0843 33 0.1451 0.0836 34 0.1450 0.0833 35 0.1437 0.0830 36 0.1420 0.0829 37 0.1383 0.0821 38 0.1355 0.0812 39 0.1327 0.0809 40 0.1323 0.0807 41 0.1275 0.0806 42 0.1274 0.0802 43 0.1252 0.0801 44 0.1228 0.0798 45 0.1189 0.0790 46 0.1187 0.0788 47 0.1171 0.0771 48 0.1157 0.0770 49 0.1131 0.0751 50 0.1113 0.0748 51 0.1063 0.0743 52 0.1035 0.0732 53 0.0960 0.0723 54 0.0894 0.0712 55 0.0758 0.0702 56 0.0718 0.0699 57 0.0675 0.0690 58 0.0671 0.0685 59 0.0446 0.0650 60 0.0237 0.0640 61 0.0161 0.0618 Pond 4 10/24/2017 5:10:30 PM Page 13 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0856 17802 14491 81 Pass 0.0889 16514 10868 65 Pass 0.0923 15049 9561 63 Pass 0.0957 14050 8611 61 Pass 0.0990 12816 6806 53 Pass 0.1024 11929 5452 45 Pass 0.1058 11101 4128 37 Pass 0.1091 10143 4004 39 Pass 0.1125 9475 3931 41 Pass 0.1159 8883 3865 43 Pass 0.1192 8181 3786 46 Pass 0.1226 7687 3732 48 Pass 0.1260 7204 3670 50 Pass 0.1293 6622 3604 54 Pass 0.1327 6228 3563 57 Pass 0.1361 5781 3503 60 Pass 0.1394 5473 3452 63 Pass 0.1428 5183 3388 65 Pass 0.1462 4819 3268 67 Pass 0.1495 4569 3172 69 Pass 0.1529 4329 3086 71 Pass 0.1563 4036 2973 73 Pass 0.1596 3829 2911 76 Pass 0.1630 3546 2802 79 Pass 0.1664 3360 2714 80 Pass 0.1697 3176 2650 83 Pass 0.1731 2954 2537 85 Pass 0.1765 2802 2443 87 Pass 0.1798 2642 2372 89 Pass 0.1832 2453 2231 90 Pass 0.1866 2331 2126 91 Pass 0.1900 2194 2039 92 Pass 0.1933 2042 1904 93 Pass 0.1967 1927 1786 92 Pass 0.2001 1790 1641 91 Pass 0.2034 1709 1535 89 Pass 0.2068 1615 1447 89 Pass 0.2102 1486 1345 90 Pass 0.2135 1391 1268 91 Pass 0.2169 1311 1189 90 Pass 0.2203 1225 1061 86 Pass 0.2236 1168 973 83 Pass 0.2270 1114 886 79 Pass 0.2304 1053 771 73 Pass 0.2337 1006 714 70 Pass 0.2371 930 645 69 Pass 0.2405 890 581 65 Pass 0.2438 848 496 58 Pass 0.2472 790 398 50 Pass 0.2506 747 350 46 Pass 0.2539 723 313 43 Pass 0.2573 673 276 41 Pass 0.2607 639 236 36 Pass Pond 4 10/24/2017 5:10:30 PM Page 14 0.2640 596 181 30 Pass 0.2674 569 152 26 Pass 0.2708 543 140 25 Pass 0.2741 497 135 27 Pass 0.2775 477 130 27 Pass 0.2809 445 125 28 Pass 0.2842 402 120 29 Pass 0.2876 376 115 30 Pass 0.2910 353 111 31 Pass 0.2943 325 103 31 Pass 0.2977 301 86 28 Pass 0.3011 272 61 22 Pass 0.3045 258 51 19 Pass 0.3078 239 40 16 Pass 0.3112 218 23 10 Pass 0.3146 202 0 0 Pass 0.3179 186 0 0 Pass 0.3213 158 0 0 Pass 0.3247 146 0 0 Pass 0.3280 129 0 0 Pass 0.3314 119 0 0 Pass 0.3348 110 0 0 Pass 0.3381 97 0 0 Pass 0.3415 93 0 0 Pass 0.3449 87 0 0 Pass 0.3482 76 0 0 Pass 0.3516 69 0 0 Pass 0.3550 63 0 0 Pass 0.3583 55 0 0 Pass 0.3617 48 0 0 Pass 0.3651 41 0 0 Pass 0.3684 38 0 0 Pass 0.3718 33 0 0 Pass 0.3752 27 0 0 Pass 0.3785 23 0 0 Pass 0.3819 21 0 0 Pass 0.3853 20 0 0 Pass 0.3886 19 0 0 Pass 0.3920 17 0 0 Pass 0.3954 14 0 0 Pass 0.3987 13 0 0 Pass 0.4021 9 0 0 Pass 0.4055 4 0 0 Pass 0.4088 3 0 0 Pass 0.4122 3 0 0 Pass 0.4156 3 0 0 Pass 0.4190 3 0 0 Pass Pond 4 10/24/2017 5:10:39 PM Page 18 Appendix Predeveloped Schematic Pond 4 10/24/2017 5:10:39 PM Page 19 Mitigated Schematic Pond 5 10/24/2017 5:18:29 PM Page 2 General Model Information Project Name:Pond 5 Site Name: Site Address: City: Report Date:10/24/2017 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 Pond 5 10/24/2017 5:18:29 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 5 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 11.63 Pervious Total 11.63 Impervious Land Use acre Impervious Total 0 Basin Total 11.63 Element Flows To: Surface Interflow Groundwater Pond 5 10/24/2017 5:18:29 PM Page 4 Mitigated Land Use Basin 5 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 1.54 Pervious Total 1.54 Impervious Land Use acre ROADS FLAT 2.66 ROOF TOPS FLAT 6.49 SIDEWALKS FLAT 0.33 POND 0.04 Impervious Total 9.52 Basin Total 11.06 Element Flows To: Surface Interflow Groundwater Pond 5 Pond 5 Pond 5 10/24/2017 5:18:29 PM Page 5 Basin 5 Bypass Bypass:Yes GroundWater:No Pervious Land Use acre C, Lawn, Flat 0.06 Pervious Total 0.06 Impervious Land Use acre ROADS FLAT 0.51 Impervious Total 0.51 Basin Total 0.57 Element Flows To: Surface Interflow Groundwater Pond 5 10/24/2017 5:18:29 PM Page 7 Mitigated Routing Pond 5 Bottom Length:100.00 ft. Bottom Width:100.00 ft. Depth:7 ft. Volume at riser head:1.7580 acre-feet. Side slope 1:2 To 1 Side slope 2:2 To 1 Side slope 3:2 To 1 Side slope 4:2 To 1 Discharge Structure Riser Height:6 ft. Riser Diameter:18 in. Orifice 1 Diameter:1.75 in.Elevation:0 ft. Orifice 2 Diameter:2.125 in.Elevation:2.75 ft. Orifice 3 Diameter:2.75 in.Elevation:3.75 ft. Element Flows To: Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.229 0.000 0.000 0.000 0.0778 0.231 0.017 0.023 0.000 0.1556 0.232 0.035 0.032 0.000 0.2333 0.233 0.054 0.040 0.000 0.3111 0.235 0.072 0.046 0.000 0.3889 0.236 0.090 0.051 0.000 0.4667 0.238 0.109 0.056 0.000 0.5444 0.239 0.127 0.061 0.000 0.6222 0.241 0.146 0.065 0.000 0.7000 0.242 0.165 0.069 0.000 0.7778 0.244 0.184 0.073 0.000 0.8556 0.245 0.203 0.076 0.000 0.9333 0.247 0.222 0.080 0.000 1.0111 0.248 0.241 0.083 0.000 1.0889 0.250 0.261 0.086 0.000 1.1667 0.251 0.280 0.089 0.000 1.2444 0.253 0.300 0.092 0.000 1.3222 0.254 0.319 0.095 0.000 1.4000 0.256 0.339 0.098 0.000 1.4778 0.257 0.359 0.101 0.000 1.5556 0.259 0.379 0.103 0.000 1.6333 0.260 0.400 0.106 0.000 1.7111 0.262 0.420 0.108 0.000 1.7889 0.263 0.440 0.111 0.000 1.8667 0.265 0.461 0.113 0.000 1.9444 0.266 0.482 0.115 0.000 2.0222 0.268 0.502 0.118 0.000 2.1000 0.269 0.523 0.120 0.000 2.1778 0.271 0.544 0.122 0.000 2.2556 0.272 0.565 0.124 0.000 2.3333 0.274 0.587 0.126 0.000 2.4111 0.276 0.608 0.129 0.000 2.4889 0.277 0.630 0.131 0.000 Pond 5 10/24/2017 5:18:29 PM Page 8 2.5667 0.279 0.651 0.133 0.000 2.6444 0.280 0.673 0.135 0.000 2.7222 0.282 0.695 0.137 0.000 2.8000 0.283 0.717 0.166 0.000 2.8778 0.285 0.739 0.184 0.000 2.9556 0.287 0.761 0.198 0.000 3.0333 0.288 0.784 0.210 0.000 3.1111 0.290 0.806 0.220 0.000 3.1889 0.291 0.829 0.229 0.000 3.2667 0.293 0.852 0.238 0.000 3.3444 0.295 0.875 0.246 0.000 3.4222 0.296 0.898 0.254 0.000 3.5000 0.298 0.921 0.261 0.000 3.5778 0.300 0.944 0.268 0.000 3.6556 0.301 0.967 0.275 0.000 3.7333 0.303 0.991 0.282 0.000 3.8111 0.304 1.015 0.339 0.000 3.8889 0.306 1.038 0.371 0.000 3.9667 0.308 1.062 0.396 0.000 4.0444 0.309 1.086 0.417 0.000 4.1222 0.311 1.110 0.437 0.000 4.2000 0.313 1.135 0.455 0.000 4.2778 0.314 1.159 0.472 0.000 4.3556 0.316 1.184 0.488 0.000 4.4333 0.318 1.208 0.503 0.000 4.5111 0.319 1.233 0.518 0.000 4.5889 0.321 1.258 0.532 0.000 4.6667 0.323 1.283 0.545 0.000 4.7444 0.325 1.309 0.558 0.000 4.8222 0.326 1.334 0.571 0.000 4.9000 0.328 1.359 0.583 0.000 4.9778 0.330 1.385 0.595 0.000 5.0556 0.331 1.411 0.607 0.000 5.1333 0.333 1.437 0.618 0.000 5.2111 0.335 1.463 0.630 0.000 5.2889 0.337 1.489 0.641 0.000 5.3667 0.338 1.515 0.651 0.000 5.4444 0.340 1.541 0.662 0.000 5.5222 0.342 1.568 0.672 0.000 5.6000 0.343 1.595 0.682 0.000 5.6778 0.345 1.621 0.692 0.000 5.7556 0.347 1.648 0.702 0.000 5.8333 0.349 1.675 0.712 0.000 5.9111 0.351 1.703 0.721 0.000 5.9889 0.352 1.730 0.731 0.000 6.0667 0.354 1.758 1.013 0.000 6.1444 0.356 1.785 1.618 0.000 6.2222 0.358 1.813 2.395 0.000 6.3000 0.359 1.841 3.268 0.000 6.3778 0.361 1.869 4.162 0.000 6.4556 0.363 1.897 5.000 0.000 6.5333 0.365 1.926 5.717 0.000 6.6111 0.367 1.954 6.269 0.000 6.6889 0.368 1.983 6.658 0.000 6.7667 0.370 2.011 7.023 0.000 6.8444 0.372 2.040 7.338 0.000 6.9222 0.374 2.069 7.640 0.000 7.0000 0.376 2.098 7.929 0.000 Pond 5 10/24/2017 5:18:29 PM Page 9 7.0778 0.378 2.128 8.207 0.000 Pond 5 10/24/2017 5:18:29 PM Page 10 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:11.63 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:1.6 Total Impervious Area:10.03 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.341932 5 year 0.537017 10 year 0.647575 25 year 0.764702 50 year 0.83718 100 year 0.898827 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.797759 5 year 1.564348 10 year 2.342229 25 year 3.751659 50 year 5.203809 100 year 7.094559 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.336 0.580 1950 0.419 0.702 1951 0.753 1.935 1952 0.237 0.363 1953 0.192 0.567 1954 0.295 0.593 1955 0.470 0.775 1956 0.374 0.707 1957 0.302 0.706 1958 0.340 0.694 Pond 5 10/24/2017 5:18:59 PM Page 11 1959 0.292 0.641 1960 0.509 2.488 1961 0.287 0.687 1962 0.179 0.287 1963 0.245 0.627 1964 0.323 0.549 1965 0.231 0.651 1966 0.222 0.493 1967 0.465 0.715 1968 0.290 0.601 1969 0.284 0.581 1970 0.234 0.508 1971 0.250 0.730 1972 0.561 0.818 1973 0.255 0.614 1974 0.276 0.572 1975 0.375 0.757 1976 0.271 0.583 1977 0.032 0.515 1978 0.238 0.581 1979 0.144 0.353 1980 0.531 1.291 1981 0.212 0.539 1982 0.408 4.495 1983 0.366 0.706 1984 0.226 0.475 1985 0.134 0.567 1986 0.593 2.000 1987 0.524 2.679 1988 0.207 0.489 1989 0.135 0.498 1990 1.096 4.253 1991 0.660 3.075 1992 0.255 0.531 1993 0.265 0.516 1994 0.089 0.315 1995 0.380 0.731 1996 0.801 2.892 1997 0.670 2.274 1998 0.152 0.664 1999 0.628 1.832 2000 0.264 0.704 2001 0.047 0.442 2002 0.290 2.143 2003 0.370 0.543 2004 0.479 4.901 2005 0.343 0.700 2006 0.405 0.740 2007 0.814 4.098 2008 1.050 4.716 2009 0.515 1.947 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.0961 4.9007 2 1.0495 4.7159 3 0.8136 4.4953 Pond 5 10/24/2017 5:18:59 PM Page 12 4 0.8012 4.2528 5 0.7530 4.0985 6 0.6697 3.0748 7 0.6600 2.8923 8 0.6281 2.6792 9 0.5927 2.4879 10 0.5607 2.2740 11 0.5314 2.1435 12 0.5242 1.9997 13 0.5153 1.9472 14 0.5091 1.9349 15 0.4785 1.8319 16 0.4699 1.2907 17 0.4649 0.8180 18 0.4188 0.7746 19 0.4085 0.7570 20 0.4049 0.7397 21 0.3802 0.7306 22 0.3746 0.7302 23 0.3739 0.7147 24 0.3696 0.7067 25 0.3662 0.7060 26 0.3433 0.7057 27 0.3400 0.7045 28 0.3359 0.7021 29 0.3230 0.7003 30 0.3018 0.6942 31 0.2947 0.6873 32 0.2916 0.6643 33 0.2900 0.6511 34 0.2897 0.6410 35 0.2872 0.6266 36 0.2837 0.6137 37 0.2765 0.6013 38 0.2708 0.5934 39 0.2651 0.5833 40 0.2644 0.5814 41 0.2547 0.5806 42 0.2545 0.5798 43 0.2502 0.5716 44 0.2454 0.5672 45 0.2376 0.5672 46 0.2373 0.5485 47 0.2340 0.5432 48 0.2313 0.5394 49 0.2261 0.5306 50 0.2223 0.5163 51 0.2124 0.5146 52 0.2069 0.5080 53 0.1919 0.4978 54 0.1787 0.4932 55 0.1515 0.4892 56 0.1436 0.4751 57 0.1350 0.4424 58 0.1341 0.3630 59 0.0891 0.3527 60 0.0474 0.3151 61 0.0322 0.2869 Pond 5 10/24/2017 5:18:59 PM Page 14 Duration Flows Flow(cfs)Predev Mit Percentage Pass/Fail 0.1710 17774 69556 391 Fail 0.1777 16296 66113 405 Fail 0.1844 15028 63118 420 Fail 0.1912 13873 60167 433 Fail 0.1979 12942 57536 444 Fail 0.2046 11905 54477 457 Fail 0.2113 10938 51355 469 Fail 0.2181 10121 48339 477 Fail 0.2248 9465 45686 482 Fail 0.2315 8787 42500 483 Fail 0.2383 8166 39527 484 Fail 0.2450 7672 37024 482 Fail 0.2517 7112 34137 479 Fail 0.2584 6609 31356 474 Fail 0.2652 6156 28640 465 Fail 0.2719 5818 26372 453 Fail 0.2786 5463 23742 434 Fail 0.2854 5120 21410 418 Fail 0.2921 4808 19937 414 Fail 0.2988 4556 19090 419 Fail 0.3056 4271 18320 428 Fail 0.3123 4025 17646 438 Fail 0.3190 3782 17111 452 Fail 0.3257 3566 16732 469 Fail 0.3325 3352 16309 486 Fail 0.3392 3140 15939 507 Fail 0.3459 2973 15620 525 Fail 0.3527 2796 15218 544 Fail 0.3594 2603 14840 570 Fail 0.3661 2449 14433 589 Fail 0.3728 2325 14055 604 Fail 0.3796 2169 13687 631 Fail 0.3863 2032 13327 655 Fail 0.3930 1898 12953 682 Fail 0.3998 1800 12604 700 Fail 0.4065 1698 12198 718 Fail 0.4132 1590 11755 739 Fail 0.4200 1497 11396 761 Fail 0.4267 1387 11011 793 Fail 0.4334 1295 10652 822 Fail 0.4401 1221 10269 841 Fail 0.4469 1161 9935 855 Fail 0.4536 1101 9554 867 Fail 0.4603 1049 9180 875 Fail 0.4671 997 8795 882 Fail 0.4738 937 8508 908 Fail 0.4805 885 8194 925 Fail 0.4872 839 7820 932 Fail 0.4940 794 7497 944 Fail 0.5007 745 7146 959 Fail 0.5074 718 6819 949 Fail 0.5142 670 6517 972 Fail 0.5209 634 6265 988 Fail 0.5276 599 5970 996 Fail Pond 5 10/24/2017 5:18:59 PM Page 15 0.5344 567 5711 1007 Fail 0.5411 539 5488 1018 Fail 0.5478 501 5289 1055 Fail 0.5545 475 5071 1067 Fail 0.5613 436 4853 1113 Fail 0.5680 399 4629 1160 Fail 0.5747 371 4425 1192 Fail 0.5815 348 4239 1218 Fail 0.5882 323 4057 1256 Fail 0.5949 299 3899 1304 Fail 0.6016 275 3707 1348 Fail 0.6084 257 3518 1368 Fail 0.6151 235 3313 1409 Fail 0.6218 218 3159 1449 Fail 0.6286 200 2956 1478 Fail 0.6353 180 2789 1549 Fail 0.6420 158 2612 1653 Fail 0.6488 146 2496 1709 Fail 0.6555 130 2353 1810 Fail 0.6622 119 2201 1849 Fail 0.6689 110 2083 1893 Fail 0.6757 97 1943 2003 Fail 0.6824 91 1810 1989 Fail 0.6891 82 1677 2045 Fail 0.6959 78 1602 2053 Fail 0.7026 69 1518 2200 Fail 0.7093 61 1424 2334 Fail 0.7161 54 1364 2525 Fail 0.7228 48 1304 2716 Fail 0.7295 41 1214 2960 Fail 0.7362 38 1139 2997 Fail 0.7430 33 1077 3263 Fail 0.7497 28 1009 3603 Fail 0.7564 22 953 4331 Fail 0.7632 21 909 4328 Fail 0.7699 20 879 4395 Fail 0.7766 19 853 4489 Fail 0.7833 17 828 4870 Fail 0.7901 14 808 5771 Fail 0.7968 12 790 6583 Fail 0.8035 9 771 8566 Fail 0.8103 4 754 18850 Fail 0.8170 3 740 24666 Fail 0.8237 3 729 24300 Fail 0.8305 3 717 23900 Fail 0.8372 3 703 23433 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Pond 5 10/24/2017 5:19:07 PM Page 19 Appendix Predeveloped Schematic Pond 5 10/24/2017 5:19:07 PM Page 20 Mitigated Schematic Basin 1 9/21/2017 11:04:16 AM Page 2 General Model Information Project Name:Basin 1 Site Name: Site Address: City: Report Date:9/21/2017 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 Basin 1 9/21/2017 11:04:16 AM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 7.56 C, Pasture, Flat 6.18 Pervious Total 13.74 Impervious Land Use acre Impervious Total 0 Basin Total 13.74 Element Flows To: Surface Interflow Groundwater Basin 1 9/21/2017 11:04:16 AM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:13.74 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:13.74 Total Impervious Area:0 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.432826 5 year 0.718229 10 year 0.919879 25 year 1.182478 50 year 1.381222 100 year 1.581181 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.432826 5 year 0.718229 10 year 0.919879 25 year 1.182478 50 year 1.381222 100 year 1.581181 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.510 0.510 1950 0.619 0.619 1951 0.920 0.920 1952 0.298 0.298 1953 0.246 0.246 1954 0.368 0.368 1955 0.578 0.578 1956 0.467 0.467 1957 0.394 0.394 1958 0.423 0.423 Basin 1 9/19/2017 12:11:48 PM Page 3 Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Flat 24.21 Pervious Total 24.21 Impervious Land Use acre Impervious Total 0 Basin Total 24.21 Element Flows To: Surface Interflow Groundwater Basin 1 9/19/2017 12:11:48 PM Page 7 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:24.21 Total Impervious Area:0 Mitigated Landuse Totals for POC #1 Total Pervious Area:24.21 Total Impervious Area:0 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.711794 5 year 1.117901 10 year 1.348048 25 year 1.591869 50 year 1.742746 100 year 1.871074 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.711794 5 year 1.117901 10 year 1.348048 25 year 1.591869 50 year 1.742746 100 year 1.871074 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.699 0.699 1950 0.872 0.872 1951 1.567 1.567 1952 0.494 0.494 1953 0.399 0.399 1954 0.613 0.613 1955 0.978 0.978 1956 0.778 0.778 1957 0.628 0.628 1958 0.708 0.708 Basin 1 9/19/2017 12:12:25 PM Page 28 Disclaimer Legal Notice This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2017; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.03200 ft/ft Normal Depth 1.00 ft Diameter 1.00 ft Results Discharge 6.37 ft³/s Flow Area 0.79 ft² Wetted Perimeter 3.14 ft Hydraulic Radius 0.25 ft Top Width 0.00 ft Critical Depth 0.96 ft Percent Full 100.0 % Critical Slope 0.02798 ft/ft Velocity 8.11 ft/s Velocity Head 1.02 ft Specific Energy 2.02 ft Froude Number 0.00 Maximum Discharge 6.86 ft³/s Discharge Full 6.37 ft³/s Slope Full 0.03200 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s 12" Culvert #1 9/15/2017 11:31:13 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page GVF Output Data Upstream Velocity Infinity ft/s Normal Depth 1.00 ft Critical Depth 0.96 ft Channel Slope 0.03200 ft/ft Critical Slope 0.02798 ft/ft 12" Culvert #1 9/15/2017 11:31:13 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.03300 ft/ft Normal Depth 1.00 ft Diameter 1.00 ft Results Discharge 6.47 ft³/s Flow Area 0.79 ft² Wetted Perimeter 3.14 ft Hydraulic Radius 0.25 ft Top Width 0.00 ft Critical Depth 0.97 ft Percent Full 100.0 % Critical Slope 0.02892 ft/ft Velocity 8.24 ft/s Velocity Head 1.06 ft Specific Energy 2.06 ft Froude Number 0.00 Maximum Discharge 6.96 ft³/s Discharge Full 6.47 ft³/s Slope Full 0.03300 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s 12" Culvert #2 9/15/2017 11:30:51 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page GVF Output Data Upstream Velocity Infinity ft/s Normal Depth 1.00 ft Critical Depth 0.97 ft Channel Slope 0.03300 ft/ft Critical Slope 0.02892 ft/ft 12" Culvert #2 9/15/2017 11:30:51 AM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page