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Preliminary TIRRECEIVED CITY OF FEDERAL WAY COMMUNITY DEVELOPMENT 23 2019OCT 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 TIR Worksheet 1.2 Site Location 1.3A Existing Drainage Basin 1.3B Developed Drainage Basin 1.4 Soils Map 3.1 Drainage Complaints 3.2 Environmental Hazard Map 3.3 Downstream Analysis Flowpath Appendix Appendix A Drainage Complaints Appendix B Hydrology Model Output Appendix C Geotechnical Study (Separate Document) Appendix D Critical Areas Report (Separate Document) Appendix E Arsenic and Lead Soil Assessment (Separate Document) Appendix F Cultural Resources Report (Separate Document) Appendix G Preliminary Tree Conservation Plan (Separate Document) Appendix H Traffic Impact Analysis (Separate Document) \\esm8\engr\esm-jobs\1352\023\019\stormreport\documents\rprt - stormreport.docx 1. Project Overview The purpose of this report is to encapsulate the documents and analysis required by the Drainage Review as defined by FWRC 16.25.020 in accordance with the 2016 King County Surface Water Design Manual (KCSWDM) and the 2016 Federal Way Addendum to the King County Washington Surface Water Design Manual (Federal Way Addendum), the King County Stormwater Prevention Manual (KCSPPM), and the latest edition of the LID Technical Guidance Manual for the Puget Sound (LID Manual), for the proposed 106 Lot townhome project/plat. Existing Site: The proposed Woodlands at Redondo Creek project site is located in Section 4, Township 21, Range 4 E, W.M., situated on two separate parcels, 042104-9012 and -9221. The site is northwest of the intersection between S 304th St and 20th Ave S, in Federal Way, Washington. Both parcels are zoned RS 5.0. Parcel 042107-9012: This parcel is 21.56 acres and is located northeast of the intersection of S 304th St and Pacific Hwy S, Federal Way 98003. The property is irregular shape and is adjacent to parcel 042107-9221 to the north. The site is bordered to the north and east by single-family residences and 20th Ave S, to the south by S 304th St, and to the west by wetland buffer area and Highway 99. The parcel’s northeast corner is bordered by a Lakehaven Utility District containing a water tower and associated pavement for maintenance access. Parcel 042107-9221: This parcel is 0.36 acres and is located northeast of the intersection of S 304th St and Pacific Hwy S, Federal Way 98003. The property is rectangular shape, approximately 117’ x 135’. The property is bordered by single-family developments to the north, west, and east, and is adjacent to parcel 042107-9012 to the south. The site is currently vacant and vegetated with moderate to heavy forest and undergrowth. The site topography is characterized by a moderate westward facing slope spanning the property that descends to a natural stream area. The slope grade reaches approximately 15 percent or slightly greater near the wetland buffer where a stream is located. Proposed improvements: The plat infrastructure improvements include new public internal roadways, tracts, existing public right-of-way (frontage) improvements, associated utilities, and landscaping. Three internal roads are proposed: Road A, B (Local Type W), and C (Local Type U). Seven tracts are proposed, including critical area/NGPA, conservation/usable/open space, and storm. Frontage improvements include half-street improvements along 20th Ave S (affecting S 302nd Pl) and S 304th St (modified half-street arterial/collector Type K). Stormwater will be conveyed and collected by a series of pipes and catch basins. One flow control facility, a combined detention and water quality pond, is proposed to meet the flow control requirements conditioned with this project. Stormwater treatment is also proposed to meet the City’s required level of treatment. See section 4 of this report for a further discussion of the existing and proposed hydrology and design details. Critical Areas Wetland: A single wetland (Wetland A) is found along the western side of the site with an associated stream channel. The wetland and stream are connected to wetlands and streams to the south of S 304th St via a 30” plastic culvert. Wetland A consists of a riverine and depressional, forested, scrub-shrub and emergent wetland located along the edges of Redondo Creek, an intermittent stream that flows from Steel Lake northerly through the site. It was determined in the critical areas report that Wetland A is a Category II wetland with a 150’ buffer measured from the wetland edge. A minor amount of buffer averaging of the buffer of Wetland A is proposed due to the slope of the property and the required grading depth near the edge of the buffer. 18,674 sf of take area (along proposed Lot 47-52’s rear lot line) and 19,188 sf of give area (south side of Tract C) is proposed. It was determined, based upon inventory data and the City’s previous determination of Redondo Creek as a minor stream or non-fish bearing, that the stream is an Ns due to seasonal flow with a 35’ buffer measured from the Ordinary High Water Mark (OHWM). Tacoma Smelter Plume The subject property is located in the Tacoma Smelter Plume detect area containing 20.1 ppm to 40.0 ppm arsenic and lead concentration. A soil testing and soil cleanup (if applicable) is required as a component of the preliminary plat and SEPA applications, review, and site development. It was determined in the arsenic and lead soil assessment; further action is necessary in the area with elevated levels of arsenic and/or lead (grid area F8 - see report Figure No. 3 for details). Ecology’s guidance provides two permanent remediation options for sites with elevated lead and/or arsenic concentrations. They are: 1) Excavation and Removal and 2) Soil Mixing. Cultural Resources Investigation of the project site resulted in the observation of no cultural materials identified. None of the structures present on the property meet the historic age threshold, and no other cultural resources were found as a result of the survey. Columbia Geotechnical Associates recommends no further consideration of cultural resources as a result of our survey. Geotechnical: A geotechnical study has been completed by Earth Solutions NW, LLC. dated October 3, 2019. Based on the results of the investigation, it is ESNW’s opinion, construction of the proposed residential development is feasible from a geotechnical standpoint. Due to the dense condition and relatively high percentage of fines of the glacial till deposits across the site, infiltration is not feasible from a geotechnical standpoint. For lightly loaded pavement areas subjected primarily to passenger vehicles, the following preliminary pavement sections may be considered: • A minimum of two inches of hot mix asphalt (HMA) placed over four inches of crushed base (CRB), or; • A minimum of two inches of HMA placed over three inches of asphalt treated base (ATB). For preliminary design purposes, the following pavement sections for occasional truck traffic areas may be considered: • Three inches of hot mix asphalt (HMA) placed over six inches of crushed base (CRB), or; • Three inches of HMA placed over four-and-one-half inches of ATB. During the subsurface exploration completed on April 12, 2019, groundwater seepage was not encountered below existing grades. However, it is ESNW’s opinion the contractor should anticipate, and be prepared to respond to, localized zones of perched groundwater seepage during construction. Figure 1.1 – TIR Worksheet TIR Worksheet can be provided with the Final TIR as requested by the City. Figure 1.2 – Vicinity Map Figure 1.3A – Existing Basin Map 123469101112131415161718192122242526272930313233353637383940414344454647484950515253545556575859606162636458111213141516 17 18 2930313233 19 21 22 24 25 26 27 5 8 2930313233 35 36 37 38 39 40 41 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 1 2 3 4 6 9 10 111213141516 17 18 19 21 22 24 25 26 27 6566676865 66 67 68 77 344242 34 2828202320 23 TRACT DTRACT ETRACT FTRACT D TRACT E TRACT F C O N S U L T I N G E N G I N E E R SL L CFederal Way, WA 9800333400 8th Ave S, Suite 205THE WOODLANDS AT REDONDO CREEK AMERICAN CLASSIC HOMESTHE WOODLANDS AT REDONDO CREEKFIG. 1.3A 1 1 PACIFIC HWY S S 304TH ST20TH AVE S 20TH AVE S S 300TH STS 302ND PLn CONTOUR INTERVAL = 2' SCALE: 1" = 50' STORM POND TRACT LEGEND Figure 1.3B – Developed Basin Map 123469101112131415161718192122242526272930313233353637383940414344454647484950515253545556575859606162636458111213141516 17 18 2930313233 19 21 22 24 25 26 27 5 8 2930313233 35 36 37 38 39 40 41 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 1 2 3 4 6 9 10 111213141516 17 18 19 21 22 24 25 26 27 6566676865 66 67 68 77 344242 34 2828202320 23 TRACT DTRACT ETRACT FTRACT D TRACT E TRACT F C O N S U L T I N G E N G I N E E R SL L CFederal Way, WA 9800333400 8th Ave S, Suite 205THE WOODLANDS AT REDONDO CREEK AMERICAN CLASSIC HOMESTHE WOODLANDS AT REDONDO CREEKFIG. 1.3B 1 1 PACIFIC HWY S S 304TH ST20TH AVE S 20TH AVE S S 300TH STS 302ND PLn CONTOUR INTERVAL = 2' SCALE: 1" = 50' STORM POND TRACT LEGEND Figure 1.4 – Soils Map 2. Conditions and Requirements Summary The proposed project is subject to Stormwater Review as a result of being subject to a City of Federal way development permit and results in more than 2,000 sf of new impervious surface according to FWRC 16.15.010. This review includes KCSWDM’s Full Drainage Review Requirements, Core Requirements 1-9, and Special Requirements 1-5. Review of the 9 Core Requirements and 5 Special Requirements This section describes how the project will meet the KCSWDM Core and Special Requirements. Core Requirement No. 1 Discharge at the Natural Location The project site, located on two parcels, is within one Threshold Discharge Area with one natural discharge location where the site naturally drains northwest to a stream. Similarly, all runoff generated from the developed basin will continue to be directed toward the natural discharge location. See Figure 1.3A for the natural discharge location. Core Requirement No. 2 Off-site Analysis The off-site analysis has been documented in Section 3 of this report. Core Requirement No. 3 Flow Control The site is located within a Conservation Flow Control Area requiring at minimum Level 2 flow control standards per Section 1.2.3.1.B of the KCSWDM and the Federal Way Addendum Flow Control Application map. The flow control standard will be met through the use of a combined detention and water quality pond in the storm tract to release stormwater at approved rates. See Section 4 for more information. Core Requirement No. 4 Conveyance System The new conveyance network will be analyzed and designed with sufficient capacity to convey and contain the 25-year peak flow. Events that exceed the 25-year event that may over top the system structure will overflow toward either of the wetlands on site Stormwater conveyance calculations will be provided in Section 5 in the final Technical Information Report (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 and discussed the Erosion and Sediment Control Report. Core Requirement No. 6 Maintenance and Operations The Operations and Maintenance manual will be included with the final TIR as requested by the City. Core Requirement No. 7 Financial Guarantees and Liability All drainage facilities constructed or modified for projects will comply with the financial guarantee requirements as provided in the City of Federal Way Bond Quantities Worksheet. Bond Quantities will be provided in the final TIR as requested by the City. Core Requirement No. 8 Water Quality The site is located within the Enhanced Basic Water Quality treatment area per the Federal Way Addendum Water Quality Applications map. However, this project is a residential subdivision development in which the actual density of single-family units is less than 8 units per acre of development area per Section 1.2.8.1. Thus, reducing the Enhanced Basic Water Quality menu to the Basic Water Quality menu. See Section 4 of this report for details. Core Requirement No. 9 Flow Control BMP’s All applicable Flow Control BMP’s are listed and discussed in Section 4 of this report. Woodlands at Redondo Creek is a subdivision project on a site greater than 5 acres in size; however, is within the UGA. Therefore, on-Site BMPs were evaluated for the project site as outlined in the KCSWDM under Section 1.2.9.1.D.3 – subdivision projects on sites less than 5 acres in size OR within the UGA. Special Requirement No. 1 Other Adopted Area-Specific Requirements There are no known master drainage plans, salmon conservation plans, stormwater compliance plans, lake management plans, flood hazard management plans, or shared facility drainage plans for this project. The project is located within the Lower Puget Sound - DM/Federal Way drainage basin, which has an associated basin plan. However, this plan’s thresholds do not necessitate further mitigation at this time. However, this plan does not describe further mitigation beyond the KCSWDM’s requirements. Special Requirement No. 1 does not apply. Special Requirement No. 2 Flood Hazard Area Delineation The project does not contain nor is it adjacent to a flood hazard area for a river, stream, lake, wetland, closed depression, marine shoreline, or a King County-mapped channel migration zone. Special Requirement No. 5 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 site is a residential development and is not subject to this requirement. Special Requirement No. 4 does not apply. Special Requirement No. 5 Oil Control The project does not have a “high-use site” characteristic and is not a redevelopment of a high-use site. Special Requirement No. 5 does not apply. A “high-use site” is a commercial or industrial site that typically generates or is subject to runoff containing high concentrations of oil due to high traffic turnover, on-site vehicle or heavy or stationary equipment use, or the frequent transfer of liquid petroleum or coal derivative products. 3. Level 1 Off-Site Analysis This narrative is to provide a Level 1 Downstream Analysis for the proposed Creekside Commons development per Core Requirement #2, Section 1.2.2 of the 2016 King County Surface Water Design Manual (SWDM). The analysis is to identify and evaluate offsite flooding, erosion, and water quality problems that may be created or aggravated by the proposed project. The primary component of this offsite analysis is the downstream corridor. The second component is to evaluate the upstream drainage system to verify any offsite run- on that may impact the project. The following Level 1 downstream analysis is a qualitative survey of the downstream system of the project site and is composed of the following four tasks: Task 1 – Define and map the study area Task 2 – Downstream Resource Review for 1-mile downstream Task 3 – Field Inspection Task 4 – Drainage System Description and Problem Descriptions Task 1: Study Area Definition and Maps The project site is located within the Hylebos Creek Drainage basin, within the Central Puget Sound watershed which is a part of the Duwamish-Green water resource inventory area (WRIA #9). The drainage study area is approximately a one-mile long path encompassing the site’s downstream corridor. See Figure 3.2 for a map of the basic study area. The study area also includes a quarter mile downstream field investigation of stormwater released from the project site. See Figure 1.3A 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 Federal Way Flow Control Applications Map, the project is located within the Conservation Flow Control Area and required to comply with Level 2 Flow Control Standards. Site Soils A geotechnical study has been completed by Earth Solutions NW, LLC. dated October 3, 2019. Based on the results of the investigation, it is ESNW’s opinion, construction of the proposed residential development is feasible from a geotechnical standpoint. Due to the dense condition and relatively high percentage of fines of the glacial till deposits across the site, infiltration is not feasible from a geotechnical standpoint. Refer to the geotechnical report included as a part of the submittal package for further details. Federal Way Critical Areas Map According to Federal Way Critical Areas map: Drainage Basin – The project is located within the Lower Puget Sound - DM/Fed Way drainage basin. Wetlands – There appear to be no wetlands indicated onsite. Streams – A stream is formed at the project site outflow and is piped to the top of Redondo Creek. Erosion Hazard Area – There is an erosion hazard area both onsite and downstream of the project site. This hazard follows Redondo Creek down to the Puget Sound. Landslide Hazard Area – None mapped Lakes – None mapped Wetland: A single wetland (Wetland A) is found along the western side of the site with an associated stream channel. The wetland and stream are connected to wetlands and streams to the south of S 304th St via a 30” plastic culvert. Wetland A consists of a riverine and depressional, forested, scrub-shrub and emergent wetland located along the edges of Redondo Creek, an intermittent stream that flows from Steel Lake northerly through the site. Refer to the critical areas report included as a part of the submittal package for further details. Downstream Drainage Complaints Relevant drainage complaints within the downstream corridor were found on King County iMap. After further researching these complaints it was concluded there are currently no relevant open or closed drainage complaints. A copy of these complaints can be found in Appendix A of this report. See Figure 3.2 for a map for location of existing downstream drainage complaints. Water Quality Assessment The Department of Ecology Water Quality Assessment 303(d)/305(b) lists were reviewed to see if there are any known downstream water quality concerns. Waters whose beneficial uses are impaired by pollutants that require a water improvement project are placed in the polluted water category (Category 5) and put on the 303(d) list. The 305(b) lists all waters and all categories. Pollutants of concerns could be Bacteria, Dissolved oxygen, temperature, metals, phosphorus, turbidity, or high pH. From the site, water is tributary to an unnamed Creek (tributary to Redondo Creek). According to the assessment, Redondo Creek is classified as Category 5 water at approximately 1.1 miles downstream of the site. The Category 5 parameter is bacteria. However, this threshold does not necessitate further mitigation at this time. See Figure 3.1 in Task 4 for a map of the Water Quality Assessment. Designated water quality problems There are no designated water quality problems known at this time. Task 3: Field Inspection (Level 1 Inspection) A site visit was conducted on September 10, 2019 by ESM Consulting Engineers for the purpose of analyzing the project site and its upstream and downstream corridors. The weather conditions were overcast and approximately 61°F. The ground surface was partly saturated due to recent rainfall. A description of the drainage path is provided below. Refer to Figure 3.2 at the end of the downstream analysis for a map of the downstream reach and point locations. Upstream and onsite runoff The site is a drainage course to several upstream areas. The conveyance channel running through the site begins approximately 900 feet south at the outfall of Steel Lake and enters the southerly boundary of the site through a 36-inch culvert (approximately sized) under South 304th Street. This 36-inch discharge pipe is shown on Figure 3.2 as Point #1. From there, runoff continues in a small channel formed that runs to the northwest across the property to another 36-inch pipe, which is the natural discharge location for the project site at the northwestern corner. This second 36-inch discharge pipe is shown on Figure 3.2 as Point #2. The project area is covered in moderately dense to dense forest areas consisting of young and mature trees. Point #1 – Discharge from Steel Lake into the 36-inch culvert. Point #1 – 36-inch plastic culvert crossing under South 304th Street, discharging to the project site. Point #1 – 36-inch plastic discharge in the drainage channel that crosses the project site. Point #2 – 24-inch CMP culvert crossing under SR-99, discharging to Redondo Creek. Point #3 – At the piped system outfall, there is a concrete headwall and 24 -inch pipe that discharges onto a rip- rap slash pad. Point #3 – 24-inch CMP culvert crossing under SR-99, discharging to Redondo Creek. This is at the bottom of a 15-foot deep gulley along the northeast side of Redondo Way. Task 4: Drainage Description and Problem Descriptions The downstream drainage system is largely comprised of an unnamed stream. See Task 3 for a narrative of the downstream flow path for a quarter mile downstream of the site and a description of each reach. Downstream Drainage Problems There are no known or observed conveyance system nuisance problems, severe erosion, or flooding problems. Downstream Water Quality Problems Noted in Task 2 of the Offsite Analysis, a Bacteria (Type 1) problem was noted approximately 1.1 miles downstream. This water quality problem is beyond the quarter mile threshold to warrant mitigation as suggested in the KCSWDM Section 1.2.2.3. See Figure 3.1 below for a map of the classified 303(d) areas downstream of project site. King County Date: 10/22/2019 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 Stormwater facilities Bonded Commercial-MF Commercial-SF Construction DOT FMD Regional Residential Drainage complaints Figure 3.1 - Drainage Complaints Approximately 1/4 Mile Downstream Approximately 1 Mile Downstream Project Site King County Date: 9/12/2019 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 Po ten tia l landslidehazard areas (2016,se e e xp lana tio n--->) Erosion hazard (1990SAO) Se ismic ha zard (1 990SAO) Coal mine haza rd(1 990 SAO) Stre am (1990 class 1 class 2 pere nnial class 2 salmon id class 3 unclassified Wetlan d (1 990 Se nsitive a rea noticeon title Streams Drainag e b asins Figure 3.2 - Environmental Hazards Project Site Point #1 Point #2 Piped Flow Path (TYP) Point #3 Figure 3.3 - Downstream Analysis Flowpath Runoff from this road is collected in the thickened edge gutter along the project site boundary and enters the existing stormwater conveyance system shown. 4. Flow Control & Water Quality Facility Analysis and Design 4.1 Existing Site Hydrology The project as a whole is made up of one threshold discharge area with one natural discharge location. Generally, the site grades direct surface water west to a wetland and stream. Within these wetlands a conveyance channel/ditch conveys water diagonally across the project site starting in the south to the north corner of the project at the site’s natural discharge location. Upstream of the project, contributing runoff from the Lakehaven Water and Sewer District also drain to the conveyance channel and onsite wetlands. 4.2 Developed Site Hydrology The project as a whole is made up of one threshold discharge area. The one natural discharge location will be preserved. The proposed combined detention and water quality pond is located within an open space tract near the western property line. The facility will discharge to a flow splitter with two level flow spreaders directing flow to the stream. Upstream run-on is proposed to be dispersed through Tract E, flow onto the site, and into Road A’s conveyance system. Bypass from the onsite grading is proposed to flow through Tracts A, B and D into Wetland A and the bypass from 20th Ave S and S 304th St are proposed to flow into their respective road’s conveyance systems. The following tables represent the pre-developed and developed conditions for the project. Table 4.1 – Historic Conditions Threshold Discharge Area #1 Area Forest Mod (ac) Impervious (ac) Total (ac) Onsite* 14.62 0 14.62 Total 14.62 - 14.62 *The upstream run-on and bypass area are not included in historic conditions. Table 4.2 – Developed Conditions Threshold Discharge Area #1 Area Roof Flat (ac) Road Flat (ac) Road Mod (ac) Sidewalk Flat (ac) Lawn Flat (ac) Lawn Mod (ac) Lawn Steep (ac) Pond (ac) Total (ac) Onsite 6.24 2.38 0.83 0.00 3.16 1.37 0.00 0.64 14.62* Upstream Run- on 0.08 0.15 0.00 0.00 0.00 1.65 0.00 0.00 1.88 Bypass 0.00 0.00 0.05*** 0.29** 0.00 0.13 1.03 0.00 1.50 Total 6.32 2.53 0.88 0.29 3.16 3.15 1.03 0.64 18.00 *Area is equal to the limits of construction under developed conditions within the ROW for surfaces considered ‘New’ or ‘Replaced’. **Sidewalk was separated from road to show the proposed non-pollution generating impervious surface bypassing the site. Onsite sidewalk is included in the road area. ***Areas of asphalt overlay are not included. Thus the 0.05 ac (<5,000 sf) of new pollution generating impervious surface bypassing the site does not trigger water quality for the road. 4.3 Performance Standards Flow Control (Sec 1.2.3.2 SWDM) Stormwater systems onsite are to be designed to mitigate runoff generated from the project per the requirements of the KCSWDM. The Federal Way Flow Control Applications Map provides the area-specific flow control facility standard. The project site falls within the Conservation Flow Control Area. Conservation Flow Control areas are to apply the Level 2 flow control standard. The Level 2 flow control standard is to match developed discharge durations to predeveloped durations for the range of predeveloped discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. Also match developed peak discharge rates to predeveloped peak discharge rates for the 2- and 10- year return periods. This also assumes historic site conditions as the predeveloped condition. The flow control basin however will consist partly of non-target areas through a mitigation trade per Section 1.2.3.2.G of the KCSWDM. This section states a project’s flow control facility may be designed to mitigate an existing developed non-target surface area in trade for not mitigating part of all of the project target surface area, provided that all of the following conditions are met: • The non-target surface area must have runoff discharge characteristics (peak flow and volume) equivalent to those of the target surface area for which mitigation is being traded. Condition is met by trading a greater than or equal amount of impervious surface and a greater than or equal amount of pervious surface. • Runoff from both the target surface area being traded and the flow control facility must converge prior to discharge of the runoff from the target surface area being traded onto private property without an easement or through any area subject to erosion. All runoff from target and non-target converge to Redondo Creek downstream. • The net effect in terms of flow control at the point of convergence downstream must be the same with or without the mitigation trade. Condition is met by detaining an area equal to or greater than the target land use characteristics. • The undetained runoff from the target surface area being traded must not create a significant adverse impact to the downstream drainage systems, salmonid habitat, or properties prior to convergence with runoff from the flow control facility. The downstream corridor is well established and stabilized, no adverse impacts are anticipated. Enhanced treatment will be provided prior to discharge from the project. To confirm the Level 2 flow control standard have been met, the Western Washington Hydrology Model Version 2012 (WWHM), an approved model per 3.2.3 of the KCSWDM, has been utilized to determine the required volume of the detention system with the proposed control structure outlet dimensions. Bypass (Sec 1.2.3.2.E) On some sites, topography can make it difficult or costly to collect all target surface runoff for conveyance to the onsite flow control facility. Section 1.2.3.2.E of the SWDM allows for bypass of the flow control facility. Compensatory mitigation by the flow control facility must be provided so that the net effect at the point of convergence downstream is the same with or without the bypass. This mitigation may be waived if the existing site conditions 100-year peak discharge from the area of the bypassed target surfaces is increased by no more than 0.15 cfs and flow control BMPs are applied to the impervious surfaces. The additional upstream run-on remaining after the mitigation trade will bypass the detention facility unmitigated and will not be traded with a non-target surface (<0.15 cfs) for hydrology modeling purposes. See Table 4.3 and 4.4 for mitigation trade areas and flows. Areas of asphalt overlay are not included. Thus the 0.05 ac (<5,000 sf) of new pollution generating impervious surface bypassing the site does not trigger water quality for the road. See Table 4.2 for developed conditions. Discharge/Wetland Recharge There is one natural discharge location on the property. This location will remain undeveloped as it is a part of a stream. The combined detention and water quality pond will discharge to a flow splitter with two level flow spreaders directing flow to the stream. Upstream run-on is proposed to be dispersed through Tract E, flow onto the site, and into Road A’s conveyance system. Bypass from the onsite grading is proposed to flow through Tracts A, B and D into Wetland A and the bypass from 20th Ave S and S 304th St are proposed to flow into their respective road’s conveyance systems. Alternatively, the upstream run-on from the Lakehaven Water and Sewer District and the bypass from 20th Ave S and S 304th St could be routed and dispersed to Wetland A. The predeveloped 100-year flow is 1.389 cfs, while the upstream run-on and bypass flows are 0.825 and 0.876 cfs, respectively. Therefore, a combination of these flows (up to 1.701 cfs) is capable of recharging Wetland A. Additional analysis will be provided with final engineering. Water Quality (Sec 1.2.8.1 SWDM & 1.2.8.2.D) Stormwater treatment is required for this project as a result of exceeding the 5,000 sf PGIS site area threshold. to provide a water quality benefit to stormwater coming in contact with pollution generating impervious surfaces (PGIS) prior to discharging from the project site. The current Federal Way Water Quality Application map provides the area-specific water quality standard for the project site. This project is a residential subdivision development in which the actual density of single-family units is less than 8 units per acre of development area per Section 1.2.8.1. Thus, reducing the Enhanced Basic Water Quality menu to the Basic Water Quality menu. Preceding detention the flow rate from the drainage basin at or below which 91% of the total runoff volume will be treated. These flows are determined using WWHM. Treatment systems are proposed prior to discharge of stormwater to the natural discharge location. Further design information during application of the construction drawings. 4.4 Flow Control System The proposed combined detention and water quality pond is within Tract C of the plat. The approved hydrology model used to confirm the stormwater detention system volume is the Western Washington Hydrology Model (WWHM). The default sizing from that software complies with the Level 2 Flow Control standards. In order to meet Level 2 flow requirements, the flow control system utilizes a flow-restrictor tee with multiple orifices. The detention and water quality portion of the system are 8.0 feet and 4.0 feet deep, respectively. The predeveloped and developed project site flow rates are provided in Table 4.3 The analyzed and proposed storage volume is provided in Table 4.4 below. Table 4.3 – Flow Frequency Return Period Predeveloped (cfs) Mitigated (cfs) 2 Year 0.435 0.236 5 Year 0.713 0.380 10 Year 0.892 0.490 25 Year 1.105 0.644 50 Year 1.252 0.771 100 Year 1.389 0.907 Table 4.4 – Volumes Description Detention Volume (ac-ft) Water Quality Volume (ac-ft) Modeled, WWHM 6.38 1.38 Provided 6.84 1.55 Further control structure design, including pipe conveyance and overflow details will be provided during review of the final engineering drawings. The equivalent area for trade (upstream run-on) has similar land use characteristics compared to the target area (bypass) and is greater than the total area and flow. The additional upstream run-on remaining after the mitigation trade will bypass the detention facility unmitigated and will not be traded with a non-target surface (<0.15 cfs) for hydrology modeling purposes. See Table 4.5 and 4.6 for mitigation trade areas and flows. See Section 4.3 for further flow control standard discussion. A basin map has been provided in Figure 1.3B Table 4.5 – Mitigation Trade Area Area Target Area (Bypass) (ac) Equivalent Area for trade (Upstream Runon) (ac) Difference (ac) Pervious 1.16 1.65 +0.49 Impervious 0.35 0.23 -0.12 Total 1.51 1.88 +0.37 Table 4.6 – Mitigation Trade Flow Return Period Target Area (Bypass) (cfs) Equivalent Area for trade (Upstream Runon) (cfs) Difference (cfs) 100 Year 0.825 0.876 +0.051* Total 0.825 0.876 +0.051* *The additional upstream run-on will bypass the detention facility unmitigated and not traded for a non-target surface (<0.15 cfs). 4.5 Water Quality System: A combined detention and water quality facility is proposed to meet the basic water quality treatment required for this site. See Table 4.6 for the modeled and provided water quality volumes. Areas of asphalt overlay are not included. Thus the 0.05 ac (<5,000 sf) of new pollution generating impervious surface bypassing the site does not trigger water. See Table 4.2 for developed conditions. 4.6 Flow Control BMPs (Core Requirement #9): On-Site BMPs were evaluated for the project site as outlined in the KCSWDM under Section 1.2.9.1.D.3 – subdivision projects on sites less than 5 acres in size OR within the UGA. Target surfaces for application of Core Requirement #9 include new impervious surfaces, new pervious surface, and replaced impervious surfaces. Implementation of flow control BMPs will be deferred until a permit is obtained for construction on each lot. The BMP’s required for the plat infrastructure per KCSWDM Section 1.2.9.4 (e.g. road and sidewalk etc.) are described in order of precedence below with feasibility determined. Requirement #1 Full Dispersion (Section C.2.1) has been evaluated for the project site. There is insufficient onsite native vegetated flow path to which target impervious surfaces may be dispersed. Therefore, minimum design requirement #1 (specified in Section C.2.1.1) cannot be met; hence, this BMP is infeasible for the project site. Requirement #2 Full Infiltration (Section C.2.2 or Section 5.2, whichever is applicable) has been evaluated. A geotechnical study has been conducted by Earth Solutions NW, LLC, dated October 3, 2019. Due to the dense condition and relatively high percentage of fines of the glacial till deposits across the site, infiltration is not feasible from a geotechnical standpoint. Therefore, the Soils requirement (specified in Section 5.2.1 - Soils) cannot be met; hence, this BMP is infeasible for the project site. Limited Infiltration (Section C.2.3) is subject to the same minimum design requirements as Full Infiltration (per Section C.2.3.2). Since Full Infiltration has been deemed infeasible, Limited Infiltration is also infeasible for this project site. Bioretention (Section C2.6) is not a suitable BMP for this project site. In order to satisfy Core Requirement #9, bioretention facilities are not allowed to have an under-drain (per Section C.2.6.1.5). Because infiltration is infeasible onsite, the draw-down time for any bioretention facilities would likely exceed 24-hours and is estimated to enable mosquito breeding (Section C.2.6: Ponding Depth and Surface Water Draw-Down). Permeable Pavement (Section C.2.7) is not a suitable BMP for this project site due to existing shallow till layer that will restrict the percolations of water. Requirement #3 Basic Dispersion (Section C.2.4) has been evaluated for the project site. Most stormwater from the new meandering sidewalks will disperse through the adjacent vegetation. Most new plat infrastructure including new road, curb, gutter, and sidewalk will flow to the proposed conveyance system within the right-of-way without opportunity for basic dispersion. Requirement #6 All new pervious surfaces will be amended in accordance with KCC 16.82.100(F) and (G) to satisfy the requirements specified therein (notes will be included on the final landscape plans). 5. Conveyance System Analysis and Design Onsite Conveyance System: Runoff from the developed project site will be collected from the developed lot lawns, roofs, drive aisles, and parking area by the proposed the conveyance system located throughout the project. The proposed stormwater drainage system is composed of catch basin structures with 6-inch and 12-inch diameter pipes. A conveyance and backwater analysis will be completed to verify the capacity of the critical pipes in the system. The proposed stormwater drainage system will be designed to convey the 25-year peak flow rate generated by the developed tributary basin as required in the SWDM. Conveyance calculations will be provided with the final TIR. 6. Special Reports and Studies Geotechnical Study Geotechnical Engineering Study Proposed Woodlands at Redondo Creek Residential Development, October 3, 2019; prepared by Earth Solutions NW, LLC. This study has been included as a part of the project submittal package. Critical Areas Report Critical Areas Report - “Woodlands at Redondo”, October 11, 2019; prepared by Sewall Wetland Consulting, Inc. This study has been included as a part of the project submittal package. Arsenic and Lead Soil Assessment Arsenic and Lead Soil Assessment, July 27, 2019; prepared by ECI Environmental Services. This study has been included as a part of the project submittal package. Cultural Resources Report Cultural Resource Assessment for The Danilchik Plat, Federal Way, King County, Washington, June 2019; prepared by Columbia Geotechnical Associates, Inc. This study has been included as a part of the project submittal package. Preliminary Tree Conservation Plan Preliminary Tree Conservation Plan, June 14, 2019; prepared by Washington Forestry Consultants, Inc. This study has been included as a part of the project submittal package. Traffic Impact Analysis The Woodlands at Redondo Creek Revised Traffic Impact Analysis, September 28, 2019; prepared by TraffEx Northwest Traffic Experts. This study has been included as a part of the project submittal package. 7. Other Permits Building permits will be required for this project, together with permits for utility connections. 8. ESC Analysis and Design The Erosion and Sedimentation Control 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. 10. Operations and Maintenance The Operations and Maintenance manual will be provided with the final TIR. Appendix A – Drainage Complaints Open SC Address Logged Date Description Response Issue:Flooding/Nuisance Water Service Request ID:S-0217-0096 Steel Lake outlet S 304th St east of SR99 2/13/2017 Hollie says Steel Lake resident has water going over his bulkhead and possibly due to outlet getting clogged and keeping the lake level high. Please check the outlet near S 304th St east of SR99 Hollie advised Ryan in person at 9am mt 2/13/17 Ryan inspected outlet channel culvert at 304th . Culvert pipe was exposed on both sides of 304th . Water level is 6 inches below top of pipe. Ryan called Ed and left message of pipe condition. Ryan Thomas 2/14/17 Service Request ID:S-0312-0005 10/18/2019 8:33:55 AM Page 1 of 17 Address Logged Date Description Response 30445 20th Ave S 3/21/2012 Per Jeff's Email I’ve been regularly checking the Steel Lake water level and noticed that the level went up significantly after the snow, ice and wind event since lots of limbs, tops and trees went down. The level raised even more after the intense rainfall last week which likely flushed leaves and woody debris into multiple jams downstream of the S. 304th Street culvert. I received a call yesterday from Gary Smith who leaves in the lowest house on Steel Lake at 30445 20th Ave. South asking if the city would check out the outlet channel. Gary asked for a return call or email to advise of our findings at 253-941-3581 or via email at: GSmith2611@AOL.com. Note that the new intake debris guard at SR99 likely also needs cleaning. With Will’s concurrence, please look at the channel downstream of the S. 304th Street culvert and advise Gary of your our findings. Gary Nieffer of the City’s Surface Water maintenance staff walked the outlet channel yesterday. Gary found no obstructions at the new intake debris guard. The outlet channel is flowing slowly at the HWY 99 inlet. Further upstream the channel starts to get deeper and deeper. The channel has no visible signs of blockage. The channel is several feet deep at the 304th Street culvert. The culvert is clear of any obstructions. There are several trees leaning over the channel North of the 304th Street culvert. The trees are in 3-4 feet of water. It is impossible to determine what is slowing the flow in the outlet channel at this time. The City’s portion of this channel is clear of any obstructions. E-mail sent to Gary Smith. *Complete* 10/18/2019 8:33:55 AM Page 2 of 17 Address Logged Date Description Response Issue:Garbage Service Request ID:S-0419-0093 29900 Pac Hwy S 4/18/2019 Trash from transients that moved from their camps (old luggage, blankets, etc.) lying on and next to the sidewalk per FWPD. 4/18: Gene ran and looked - it is 1 load that will be picked up in the am. - ss Picked up and disposed by crew, 4/19 Service Request ID:S-1118-0121 S 304th St half block east of SR99 11/29/2018 large piece of furniture dumped in ditch on S 304th St east of SR99 Picked up by crew and disposed at SLM Service Request ID:S-1216-0117 NB Pac Hwy @ 29900 block 12/28/2016 A 6-foot tall industrial cart is blocking the sidewalk. It's full of construction debris and covered with a tarp. It's on the NB side of Pac Hwy @ the 29900 block. 12/28 DISPATCHED to Gene @ 1:30pm ~su Picked up by crew and disposed at King County transfer station 10/18/2019 8:33:55 AM Page 3 of 17 Address Logged Date Description Response Issue:IDDE Investigation Service Request ID:S-0712-0030 30405 PACIFIC HWY S 7/31/2012 Report of gasoline spill at 76 station Report form Ecology (ERTs) generated on a Saturday 10/16 concerning a gasoline spill at 76 station. SWM water quality inspection on Monday 10/18. Business employee says that a small amount of gas was spilled from a portable container and properly cleaned up. Inspection of site stormwater system indicates no impacts to MS4. No further action. Service Request ID:S-0818-0079 10/18/2019 8:33:55 AM Page 4 of 17 Address Logged Date Description Response 2012 S 302nd Pl 8/20/2018 Report of a horrible smell coming up from storm drain across the street from 2017 S 302nd Pl. Voicemail was garbled, couldn't make out caller's name, but she did request a call back. 10/18/2019 8:33:55 AM Page 5 of 17 Address Logged Date Description Response 8/30/18: Maint. responded. Possible illegal Tee in 6" PVC Pipe in CB. Both CBs smell and have grey matter. 9/5/18: Fwd to JL to investigate. 9/6/18: JL and AB onsite. Active illicit discharge from a 6" pvc pipe tied to CB #4622 with a very pungent odor of sewage. Storm lines and CBs contaminated with sewage/grey matter. Storm lines and CBs likely all contaminated starting at CB#4622 going S to City Pond #1 to pond inlet, pipe #8964. JL and AB used push camera to video inspect the 6" pvc pipe, sewage/gray matter were visible within 6"pvc pipe. Illicit connection point unknown. JL contacted RT to coordinate cleaning of storm lines and CBs. Addtl. investigation needed to find and terminate connection point. Addtl. cleaning may be necessary after. 9/7: CB vactored. lm 9/10: RT advised PD on possible meth waste. lm 9/17: Determined to be food wastes from PO cleaning into downspout from outdoor kitchen. lm 9/24: NOV sent; check CB 10/12. lm 10/16: Mike site check; looks good. lm 10/18: Close-out sent. lm 10/18/2019 8:33:55 AM Page 6 of 17 Address Logged Date Description Response 10/18/2019 8:33:55 AM Page 7 of 17 Address Logged Date Description Response Issue:Item in Right-of-way (not garbage) Service Request ID:S-1217-0050 S 304th St just east of Pacific Hwy S 12/11/2017 Shopping carts in row on S 304th St just east of Pacific Hwy S. called out to Gene at 10:25 am. av 10/18/2019 8:33:55 AM Page 8 of 17 Address Logged Date Description Response Issue:Other (Surface Water) Service Request ID:S-0817-0085 2013 S 304th St 8/24/2017 Grant Sartison called, said he tried digging a trench in his yard and discovered a drainage pipe that is broken and full of dirt. Wants City to see if this is a City pipe or not. PaulH: I checked our records....we have no record of any city drainage, or any drainage at all in the area of this address. I have NOT called Grant yet...i'll leave it to Ryan just in case he wants to go take a look at it. GARY NEIFFER TALKED TO HOMEOWNER AND GAVE HIM IDEAS ON HOW TO REPLACE DRAIN PIPE. PIPE WAS PLACED IN FRONT OF A CURB YEARS AGO TO INTERCEPT WATER RUNOFF. 10/18/2019 8:33:55 AM Page 9 of 17 Address Logged Date Description Response Issue:Signals Service Request ID:S-0219-0091 Pacific Hwys S & s 304 th ST 2/9/2019 Pacific Hwys S & s 304 th ST cross walk beeps all day and night without anyone requesting to cross the intersection. The beeping disturbs our business and customers who are waiting for service. It’s soo loud it can be heard over the phone while speaking inside the building. It’s a constant beep that is disturbing to our ears and operation. Ryan T forwarded this to King County for repair. Service Request ID:S-0617-0070 S 304th St @ Pac Hwy 6/20/2017 EB/WB signals on S 304th to cross over Pac Hwy are short-cycling. 6/19 DISPATCHED to King Co @ 10am ~su 7/10/17 This issue still happening, called in by another citizen. Re- dispatched to KC 11:30am mt 7/10/17 7/18 - KC found WB detection zones shifted, after realignment saw normal operation. ~ep 10/18/2019 8:33:55 AM Page 10 of 17 Address Logged Date Description Response Issue:Signs Service Request ID:S-0219-0003 East Side of Pac Hwy / N of S 304th St 2/1/2019 2 signs down 1) Speed Limit 45 MPH and 2) Dash Point State Park Called KC - ss Service Request ID:S-0417-0018 SR 99 / S 304 St 4/5/2017 Right-turn Yield to U-turn sign down on NE corner of intersection. 4/4 - Dispatched King County ~ ep 10/18/2019 8:33:55 AM Page 11 of 17 Address Logged Date Description Response Issue:Snow / Ice Service Request ID:S-0219-0194 S 301st PLACE, FEDERAL WAY 98003 2/12/2019 We cannot drive up our hill, please plow a path for us glitch in vueworks that reopened snow and ice - reclosing mt 6/27/19 Service Request ID:S-0219-0284 S Bound Pac Hwy between Dash Pt Rd and S 304th 2/14/2019 Icy Issue completed by crew - ss 10/18/2019 8:33:55 AM Page 12 of 17 Address Logged Date Description Response Issue:Street Lights - King County Service Request ID:S-1016-0086 2015 S 301st Place 10/20/2016 Resident complained that streetlight near their house is leaning, rusty and not very bright. They also requested an additional streetlight at the 21 Ave S / S 301 Pl intersection. Working with PSE to either replace dim light or upgrade to LED. Will review collision history and evaluate additional lighting request at 21s301p intersection. Collision History does not support a need for additional street lighting. PSE will replace existing lights with like light types if fixtures are dim below standard. 10/18/2019 8:33:55 AM Page 13 of 17 Address Logged Date Description Response Issue:Street Lights - PSE Service Request ID:S-0318-0021 1651 S 304th St 3/6/2018 Second street light at 1651 S 304th St. Pole # 2579 Reported on-line to PSE. av Service Request ID:S-0318-0022 third street light on the south side of S 304th St, beginning east of Pacific Hwy S 3/6/2018 The third street light on the south side of S 304th St, beginning east of Pacific Hwy S is out. Reported on-line to PSE Service Request ID:S-0318-0023 fourth street light on the south side of S 304th St, beginning east of Pacific Hwy S 3/6/2018 The fourth street light on the south side of S 304th St, beginning east of Pacific Hwy S Called out to PSE. av 10/18/2019 8:33:55 AM Page 14 of 17 Address Logged Date Description Response Issue:Trees (dangerous or downed) Service Request ID:S-0817-0028 300 block of Pacific Highway 8/7/2017 Street trees blocking sidewalk down due to accident Terome responded and removed trees and vehicle debris 10/18/2019 8:33:55 AM Page 15 of 17 Address Logged Date Description Response Issue:Vegetation Service Request ID:S-0417-0121 north side of S 304th St between 20th Ave S & SR99 4/28/2017 Overhanging branches that could potentially fall or pose hazard on the north side of S 304th St somewhere between 20th Ave S & SR99. Needs trimming. trimmed back and hauled off by crew 10/18/2019 8:33:55 AM Page 16 of 17 Address Logged Date Description Response Issue:Water Quality Complaints Service Request ID:S-1017-0078 30402 Pacific Hwy S.10/18/2017 Citizen complaint of Auto Repair facility pressure washing motors with out containing wash water. Oil and fluids making absorb into soil and flow offsite during rain events. Inspector recommends investigation and education with business owner. 10/27: Site check by Mindi and Leah revealed no obvious track-out or sediment discharge from lower parking lot. Upper parking lot where garage is located has a washwater drain in front of the garage. Will check back after a storm event. LM 11/3: Mindi and Leah checked site during snow/rain mix and no discharge is noted from the site. LM 11/9: Mindi and Leah check the site during a heavy rain event and no sediment or washwater is observed flowing offsite. The water flowing east, downhill from the corner of 304th and Pac Hwy is not turbid. No further action needed. LM 10/18/2019 8:33:55 AM Page 17 of 17 Appendix B – Hydrology Model Output WWHM2012 PROJECT REPORT General Model Information Project Name: Pond Site Name: Woodlands Site Address: W of int. of S 302nd Pl and 20th Ave S City:Federal Way Report Date: Gage:Seatac Data Start: 1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.000 Version Date: 2019/09/13 Version: 4.2.17 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Landuse Basin Data Predeveloped Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 14.62 Pervious Total 14.62 Impervious Land Use acre Impervious Total 0 Basin Total 14.62 Element Flows To:Surface Interflow Groundwater Mitigated Land Use Basin 1 Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Flat 3.16 C, Lawn, Mod 1.37 Pervious Total 4.53 Impervious Land Use acre ROADS FLAT 2.38 ROADS MOD 0.83 ROOF TOPS FLAT 6.24 POND 0.64 Impervious Total 10.09 Basin Total 14.62 Element Flows To:Surface Interflow GroundwaterPond 1 Pond 1 Mitigated Routing Pond 1 Bottom Length:250.00 ft.Bottom Width:100.00 ft.Depth:9 ft.Volume at riser head: 6.3767 acre-feet.Side slope 1:3 To 1Side slope 2:3 To 1Side slope 3:3 To 1Side slope 4:3 To 1Discharge StructureRiser Height:8 ft.Riser Diameter:36 in.Orifice 1 Diameter: 1.5 in. Elevation:0 ft.Orifice 2 Diameter: 1.75 in. Elevation:4.75 ft.Orifice 3 Diameter: 2.75 in. Elevation:5.75 ft.Element Flows To:Outlet 1 Outlet 2 Pond Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs)0.0000 0.573 0.000 0.000 0.0000.1000 0.578 0.057 0.019 0.0000.2000 0.583 0.115 0.027 0.0000.3000 0.588 0.174 0.033 0.0000.4000 0.593 0.233 0.038 0.0000.5000 0.598 0.293 0.043 0.0000.6000 0.603 0.353 0.047 0.0000.7000 0.608 0.413 0.051 0.0000.8000 0.613 0.474 0.054 0.0000.9000 0.618 0.536 0.057 0.0001.0000 0.623 0.598 0.061 0.0001.1000 0.628 0.660 0.064 0.0001.2000 0.633 0.723 0.066 0.0001.3000 0.638 0.787 0.069 0.0001.4000 0.643 0.851 0.072 0.0001.5000 0.648 0.916 0.074 0.0001.6000 0.653 0.981 0.077 0.0001.7000 0.658 1.046 0.079 0.0001.8000 0.663 1.112 0.081 0.0001.9000 0.668 1.179 0.084 0.0002.0000 0.673 1.246 0.086 0.0002.1000 0.678 1.314 0.088 0.0002.2000 0.684 1.382 0.090 0.0002.3000 0.689 1.450 0.092 0.0002.4000 0.694 1.520 0.094 0.0002.5000 0.699 1.589 0.096 0.0002.6000 0.704 1.660 0.098 0.0002.7000 0.710 1.730 0.100 0.0002.8000 0.715 1.802 0.102 0.0002.9000 0.720 1.873 0.104 0.0003.0000 0.726 1.946 0.105 0.0003.1000 0.731 2.019 0.107 0.0003.2000 0.736 2.092 0.109 0.000 3.3000 0.742 2.166 0.110 0.0003.4000 0.747 2.240 0.112 0.0003.5000 0.752 2.315 0.114 0.0003.6000 0.758 2.391 0.115 0.0003.7000 0.763 2.467 0.117 0.0003.8000 0.769 2.544 0.119 0.0003.9000 0.774 2.621 0.120 0.0004.0000 0.780 2.699 0.122 0.0004.1000 0.785 2.777 0.123 0.0004.2000 0.791 2.856 0.125 0.0004.3000 0.796 2.935 0.126 0.0004.4000 0.802 3.015 0.128 0.0004.5000 0.807 3.095 0.129 0.0004.6000 0.813 3.176 0.131 0.0004.7000 0.818 3.258 0.132 0.0004.8000 0.824 3.340 0.152 0.0004.9000 0.830 3.423 0.167 0.0005.0000 0.835 3.506 0.178 0.0005.1000 0.841 3.590 0.187 0.0005.2000 0.847 3.674 0.195 0.0005.3000 0.852 3.759 0.202 0.0005.4000 0.858 3.845 0.208 0.0005.5000 0.864 3.931 0.215 0.0005.6000 0.869 4.018 0.221 0.0005.7000 0.875 4.105 0.226 0.0005.8000 0.881 4.193 0.278 0.0005.9000 0.887 4.281 0.316 0.0006.0000 0.892 4.370 0.345 0.0006.1000 0.898 4.460 0.368 0.0006.2000 0.904 4.550 0.389 0.0006.3000 0.910 4.641 0.408 0.0006.4000 0.916 4.732 0.426 0.0006.5000 0.922 4.824 0.443 0.0006.6000 0.928 4.917 0.459 0.0006.7000 0.934 5.010 0.474 0.0006.8000 0.940 5.103 0.488 0.0006.9000 0.945 5.198 0.502 0.0007.0000 0.951 5.293 0.515 0.0007.1000 0.957 5.388 0.528 0.0007.2000 0.963 5.484 0.541 0.0007.3000 0.969 5.581 0.553 0.0007.4000 0.975 5.678 0.565 0.0007.5000 0.982 5.776 0.576 0.0007.6000 0.988 5.875 0.587 0.0007.7000 0.994 5.974 0.598 0.0007.8000 1.000 6.073 0.609 0.0007.9000 1.006 6.174 0.620 0.0008.0000 1.012 6.275 0.630 0.0008.1000 1.018 6.376 1.646 0.0008.2000 1.024 6.478 3.491 0.0008.3000 1.031 6.581 5.859 0.0008.4000 1.037 6.685 8.614 0.0008.5000 1.043 6.789 11.64 0.0008.6000 1.049 6.893 14.83 0.0008.7000 1.055 6.999 18.07 0.0008.8000 1.062 7.104 21.25 0.0008.9000 1.068 7.211 24.24 0.0009.0000 1.074 7.318 26.96 0.000 9.1000 1.081 7.426 29.33 0.000 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1Total Pervious Area: 14.62Total Impervious Area: 0 Mitigated Landuse Totals for POC #1Total Pervious Area: 4.53Total Impervious Area: 10.09 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs)2 year 0.4353135 year 0.71329910 year 0.89203925 year 1.10465850 year 1.251931100 year 1.389492 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs)2 year 0.2363985 year 0.38007610 year 0.48974225 year 0.64434550 year 0.770994100 year 0.907404 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated1949 0.501 0.1291950 0.595 0.3561951 0.951 0.6181952 0.298 0.1181953 0.241 0.2491954 0.370 0.1981955 0.592 0.1311956 0.477 0.4511957 0.385 0.1811958 0.427 0.201 1959 0.366 0.1991960 0.656 0.4041961 0.361 0.3331962 0.225 0.1181963 0.308 0.2151964 0.437 0.3361965 0.291 0.3711966 0.279 0.2101967 0.668 0.3491968 0.376 0.1741969 0.366 0.2071970 0.294 0.2241971 0.332 0.1821972 0.722 0.5161973 0.320 0.3521974 0.355 0.2261975 0.494 0.1661976 0.353 0.1811977 0.052 0.1081978 0.298 0.2341979 0.180 0.1051980 0.850 0.5151981 0.267 0.1941982 0.551 0.3671983 0.472 0.2071984 0.284 0.1261985 0.169 0.1201986 0.746 0.1891987 0.658 0.4071988 0.260 0.1291989 0.172 0.1281990 1.576 0.4361991 0.836 0.5311992 0.341 0.2091993 0.333 0.1111994 0.112 0.1061995 0.478 0.3811996 1.104 0.5831997 0.852 0.5561998 0.208 0.1301999 0.934 0.5132000 0.332 0.1852001 0.060 0.0882002 0.385 0.3152003 0.574 0.1292004 0.614 0.4852005 0.455 0.1242006 0.512 0.4262007 1.191 0.5832008 1.452 0.4712009 0.677 0.319 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated11.5763 0.617721.4523 0.583231.1915 0.5831 4 1.1039 0.555850.9511 0.531460.9341 0.515870.8519 0.514980.8500 0.513190.8361 0.4846100.7459 0.4707110.7220 0.4512120.6771 0.4359130.6684 0.4260140.6584 0.4067150.6562 0.4041160.6137 0.3810170.5947 0.3710180.5916 0.3671190.5744 0.3561200.5512 0.3518210.5123 0.3491220.5010 0.3356230.4938 0.3334240.4775 0.3188250.4766 0.3149260.4716 0.2495270.4554 0.2345280.4373 0.2259290.4272 0.2240300.3847 0.2152310.3846 0.2103320.3763 0.2089330.3703 0.2070340.3664 0.2066350.3662 0.2009360.3609 0.1988370.3547 0.1979380.3529 0.1944390.3414 0.1894400.3332 0.1854410.3318 0.1825420.3318 0.1815430.3200 0.1811440.3083 0.1736450.2985 0.1657460.2981 0.1311470.2939 0.1302480.2906 0.1294490.2840 0.1291500.2793 0.1291510.2668 0.1282520.2600 0.1258530.2412 0.1238540.2246 0.1198550.2085 0.1179560.1805 0.1179570.1721 0.1111580.1686 0.1082590.1119 0.1059600.0596 0.1050610.0517 0.0882 Duration Flows The Facility PASSED Flow(cfs) Predev Mit Percentage Pass/Fail0.2177 17207 13734 79 Pass0.2281 15496 9616 62 Pass0.2386 14125 9161 64 Pass0.2490 12900 8739 67 Pass0.2594 11612 8280 71 Pass0.2699 10596 7854 74 Pass0.2803 9599 7433 77 Pass0.2908 8816 7011 79 Pass0.3012 8055 6581 81 Pass0.3117 7388 6216 84 Pass0.3221 6740 5707 84 Pass0.3326 6218 5242 84 Pass0.3430 5726 4785 83 Pass0.3535 5324 4348 81 Pass0.3639 4952 3993 80 Pass0.3744 4579 3685 80 Pass0.3848 4263 3343 78 Pass0.3953 3957 3046 76 Pass0.4057 3655 2819 77 Pass0.4162 3390 2586 76 Pass0.4266 3146 2370 75 Pass0.4370 2915 2162 74 Pass0.4475 2716 1947 71 Pass0.4579 2505 1728 68 Pass0.4684 2325 1461 62 Pass0.4788 2147 1256 58 Pass0.4893 1974 1040 52 Pass0.4997 1833 908 49 Pass0.5102 1704 734 43 Pass0.5206 1583 606 38 Pass0.5311 1443 519 35 Pass0.5415 1329 440 33 Pass0.5520 1243 371 29 Pass0.5624 1151 313 27 Pass0.5729 1090 265 24 Pass0.5833 1021 104 10 Pass0.5938 957 62 6 Pass0.6042 887 36 4 Pass0.6147 830 17 2 Pass0.6251 760 0 0 Pass0.6355 725 0 0 Pass0.6460 678 0 0 Pass0.6564 627 0 0 Pass0.6669 591 0 0 Pass0.6773 552 0 0 Pass0.6878 507 0 0 Pass0.6982 469 0 0 Pass0.7087 428 0 0 Pass0.7191 388 0 0 Pass0.7296 356 0 0 Pass0.7400 328 0 0 Pass0.7505 298 0 0 Pass0.7609 272 0 0 Pass 0.7714 242 0 0 Pass0.7818 219 0 0 Pass0.7923 198 0 0 Pass0.8027 176 0 0 Pass0.8131 152 0 0 Pass0.8236 131 0 0 Pass0.8340 119 0 0 Pass0.8445 105 0 0 Pass0.8549 95 0 0 Pass0.8654 84 0 0 Pass0.8758 75 0 0 Pass0.8863 69 0 0 Pass0.8967 61 0 0 Pass0.9072 53 0 0 Pass0.9176 46 0 0 Pass0.9281 39 0 0 Pass0.9385 30 0 0 Pass0.9490 25 0 0 Pass0.9594 22 0 0 Pass0.9699 20 0 0 Pass0.9803 17 0 0 Pass0.9908 14 0 0 Pass1.0012 12 0 0 Pass1.0116 9 0 0 Pass1.0221 7 0 0 Pass1.0325 7 0 0 Pass1.0430 7 0 0 Pass1.0534 6 0 0 Pass1.0639 6 0 0 Pass1.0743 6 0 0 Pass1.0848 6 0 0 Pass1.0952 6 0 0 Pass1.1057 5 0 0 Pass1.1161 5 0 0 Pass1.1266 5 0 0 Pass1.1370 5 0 0 Pass1.1475 5 0 0 Pass1.1579 5 0 0 Pass1.1684 5 0 0 Pass1.1788 4 0 0 Pass1.1892 4 0 0 Pass1.1997 3 0 0 Pass1.2101 3 0 0 Pass1.2206 3 0 0 Pass1.2310 3 0 0 Pass1.2415 3 0 0 Pass1.2519 3 0 0 Pass Water Quality Water Quality BMP Flow and Volume for POC #1On-line facility volume: 1.3843 acre-feetOn-line facility target flow: 1.6245 cfs.Adjusted for 15 min: 1.6245 cfs.Off-line facility target flow: 0.9124 cfs.Adjusted for 15 min: 0.9124 cfs. Appendix Predeveloped Schematic Mitigated Schematic Predeveloped UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Pond.wdm MESSU 25 PrePond.MES 27 PrePond.L61 28 PrePond.L62 30 POCPond1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 11 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Basin 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 11 C, Forest, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 11 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 11 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 11 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 11 0 4.5 0.08 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 11 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 11 0.2 0.5 0.35 6 0.5 0.7 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 11 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 11 14.62 COPY 501 12 PERLND 11 14.62 COPY 501 13 ******Routing****** END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 END MASS-LINK END RUN Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <-----------File Name------------------------------>*** <-ID-> *** WDM 26 Pond.wdm MESSU 25 MitPond.MES 27 MitPond.L61 28 MitPond.L62 30 POCPond1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 16 PERLND 17 IMPLND 1 IMPLND 2 IMPLND 4 IMPLND 14 RCHRES 1 COPY 1 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Pond 1 MAX 1 2 30 9 END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO <PLS ><-------Name------->NBLKS Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 16 C, Lawn, Flat 1 1 1 1 27 0 17 C, Lawn, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 16 0 0 1 0 0 0 0 0 0 0 0 0 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 16 0 0 4 0 0 0 0 0 0 0 0 0 1 9 17 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 16 0 0 0 0 0 0 0 0 0 0 0 17 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 16 0 4.5 0.03 400 0.05 0.5 0.996 17 0 4.5 0.03 400 0.1 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 16 0 0 2 2 0 0 0 17 0 0 2 2 0 0 0 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 16 0.1 0.25 0.25 6 0.5 0.25 17 0.1 0.25 0.25 6 0.5 0.25 END PWAT-PARM4 PWAT-STATE1 <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 16 0 0 0 0 2.5 1 0 17 0 0 0 0 2.5 1 0 END PWAT-STATE1 END PERLND IMPLND GEN-INFO <PLS ><-------Name-------> Unit-systems Printer *** # - # User t-series Engl Metr *** in out *** 1 ROADS/FLAT 1 1 1 27 0 2 ROADS/MOD 1 1 1 27 0 4 ROOF TOPS/FLAT 1 1 1 27 0 14 POND 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 1 0 0 1 0 0 0 2 0 0 1 0 0 0 4 0 0 1 0 0 0 14 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 1 0 0 4 0 0 0 1 9 2 0 0 4 0 0 0 1 9 4 0 0 4 0 0 0 1 9 14 0 0 4 0 0 0 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 1 0 0 0 0 0 2 0 0 0 0 0 4 0 0 0 0 0 14 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 1 400 0.01 0.1 0.1 2 400 0.05 0.1 0.08 4 400 0.01 0.1 0.1 14 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 1 0 0 2 0 0 4 0 0 14 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 1 0 0 2 0 0 4 0 0 14 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Basin 1*** PERLND 16 3.16 RCHRES 1 2 PERLND 16 3.16 RCHRES 1 3 PERLND 17 1.37 RCHRES 1 2 PERLND 17 1.37 RCHRES 1 3 IMPLND 1 2.38 RCHRES 1 5 IMPLND 2 0.83 RCHRES 1 5 IMPLND 4 6.24 RCHRES 1 5 IMPLND 14 0.64 RCHRES 1 5 ******Routing****** PERLND 16 3.16 COPY 1 12 PERLND 17 1.37 COPY 1 12 IMPLND 1 2.38 COPY 1 15 IMPLND 2 0.83 COPY 1 15 IMPLND 4 6.24 COPY 1 15 IMPLND 14 0.64 COPY 1 15 PERLND 16 3.16 COPY 1 13 PERLND 17 1.37 COPY 1 13 RCHRES 1 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------><---> User T-series Engl Metr LKFG *** in out *** 1 Pond 1 1 1 1 1 28 0 1 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT-INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC A1 A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 0 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><--------><--------><--------><--------><--------> *** 1 1 0.05 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><--------> <---><---><---><---><---> *** <---><---><---><---><---> 1 0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC-ACTIONS END SPEC-ACTIONS FTABLES FTABLE 1 91 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.573921 0.000000 0.000000 0.100000 0.578750 0.057634 0.019308 0.200000 0.583596 0.115751 0.027306 0.300000 0.588458 0.174354 0.033443 0.400000 0.593337 0.233443 0.038616 0.500000 0.598232 0.293022 0.043174 0.600000 0.603144 0.353091 0.047295 0.700000 0.608073 0.413651 0.051085 0.800000 0.613017 0.474706 0.054612 0.900000 0.617979 0.536256 0.057925 1.000000 0.622957 0.598303 0.061058 1.100000 0.627951 0.660848 0.064038 1.200000 0.632962 0.723894 0.066885 1.300000 0.637990 0.787441 0.069617 1.400000 0.643034 0.851492 0.072245 1.500000 0.648095 0.916049 0.074780 1.600000 0.653172 0.981112 0.077233 1.700000 0.658265 1.046684 0.079610 1.800000 0.663376 1.112766 0.081918 1.900000 0.668502 1.179360 0.084162 2.000000 0.673646 1.246467 0.086349 2.100000 0.678805 1.314090 0.088481 2.200000 0.683982 1.382229 0.090563 2.300000 0.689174 1.450887 0.092599 2.400000 0.694384 1.520065 0.094590 2.500000 0.699610 1.589765 0.096541 2.600000 0.704852 1.659988 0.098453 2.700000 0.710111 1.730736 0.100328 2.800000 0.715387 1.802011 0.102169 2.900000 0.720679 1.873814 0.103978 3.000000 0.725987 1.946147 0.105755 3.100000 0.731312 2.019012 0.107503 3.200000 0.736654 2.092411 0.109224 3.300000 0.742012 2.166344 0.110917 3.400000 0.747387 2.240814 0.112585 3.500000 0.752778 2.315822 0.114229 3.600000 0.758185 2.391370 0.115849 3.700000 0.763610 2.467460 0.117447 3.800000 0.769051 2.544093 0.119024 3.900000 0.774508 2.621271 0.120580 4.000000 0.779982 2.698995 0.122116 4.100000 0.785472 2.777268 0.123633 4.200000 0.790979 2.856091 0.125131 4.300000 0.796502 2.935465 0.126612 4.400000 0.802042 3.015392 0.128076 4.500000 0.807599 3.095874 0.129523 4.600000 0.813172 3.176912 0.130954 4.700000 0.818761 3.258509 0.132370 4.800000 0.824367 3.340666 0.152354 4.900000 0.829990 3.423383 0.167344 5.000000 0.835629 3.506664 0.178083 5.100000 0.841285 3.590510 0.187054 5.200000 0.846957 3.674922 0.194983 5.300000 0.852646 3.759902 0.202199 5.400000 0.858351 3.845452 0.208888 5.500000 0.864073 3.931573 0.215166 5.600000 0.869811 4.018267 0.221110 5.700000 0.875566 4.105536 0.226776 5.800000 0.881337 4.193381 0.278095 5.900000 0.887125 4.281804 0.316913 6.000000 0.892929 4.370807 0.345087 6.100000 0.898750 4.460391 0.368774 6.200000 0.904588 4.550558 0.389773 6.300000 0.910442 4.641310 0.408917 6.400000 0.916312 4.732647 0.426673 6.500000 0.922199 4.824573 0.443335 6.600000 0.928103 4.917088 0.459103 6.700000 0.934023 5.010194 0.474122 6.800000 0.939960 5.103893 0.488500 6.900000 0.945913 5.198187 0.502320 7.000000 0.951882 5.293077 0.515649 7.100000 0.957869 5.388564 0.528540 7.200000 0.963871 5.484651 0.541038 7.300000 0.969891 5.581339 0.553179 7.400000 0.975927 5.678630 0.564995 7.500000 0.981979 5.776525 0.576513 7.600000 0.988048 5.875027 0.587757 7.700000 0.994133 5.974136 0.598746 7.800000 1.000235 6.073854 0.609498 7.900000 1.006354 6.174184 0.620029 8.000000 1.012489 6.275126 0.630353 8.100000 1.018640 6.376682 1.646562 8.200000 1.024808 6.478855 3.491178 8.300000 1.030993 6.581645 5.859274 8.400000 1.037194 6.685054 8.614663 8.500000 1.043411 6.789084 11.64469 8.600000 1.049646 6.893737 14.83785 8.700000 1.055896 6.999014 18.07942 8.800000 1.062163 7.104917 21.25361 8.900000 1.068447 7.211448 24.24914 9.000000 1.074747 7.318607 26.96714 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** RCHRES 1 HYDR RO 1 1 1 WDM 1000 FLOW ENGL REPL RCHRES 1 HYDR STAGE 1 1 1 WDM 1001 STAG ENGL REPL COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL END EXT TARGETS MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS-LINK 2 PERLND PWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 2 MASS-LINK 3 PERLND PWATER IFWO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 3 MASS-LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS-LINK 5 MASS-LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 12 MASS-LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS-LINK 13 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 MASS-LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS-LINK 16 END MASS-LINK END RUN General Model Information Project Name: Upstream Run-On vs. Bypass Site Name: Woodlands at Redondo Creek Site Address: W of int. of S 302nd Pl and 20th Ave S City:Federal Way Report Date: Gage:Seatac Data Start:1948/10/01 Data End: 2009/09/30 Timestep: 15 Minute Precip Scale: 1.000 Version Date: 2019/09/13 Version: 4.2.17 POC Thresholds Low Flow Threshold for POC1: 50 Percent of the 2 Year High Flow Threshold for POC1: 50 Year Low Flow Threshold for POC2: 50 Percent of the 2 Year High Flow Threshold for POC2: 50 Year Landuse Basin Data Upstream Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 1.65 Pervious Total 1.65 Impervious Land Use acre ROADS FLAT 0.15 ROOF TOPS FLAT 0.08 Impervious Total 0.23 Basin Total 1.88 Element Flows To:Surface Interflow Groundwater Bypass Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.13 C, Lawn, Steep 1.03 Pervious Total 1.16 Impervious Land Use acre ROADS MOD 0.05 SIDEWALKS MOD 0.29 Impervious Total 0.34 Basin Total 1.5 Element Flows To:Surface Interflow Groundwater Analysis Results 8SVWUHDP5XQ2Q x Unmitigated Predeveloped Landuse Totals for Upstream Run-OnTotal Pervious Area: 1.65Total Impervious Area: 0.23 Mitigated Landuse Totals for Upstream Run-OnTotal Pervious Area: 1.65Total Impervious Area: 0.23 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Upstream Run-On.Return Period Flow(cfs)2 year 0.2353915 year 0.37427510 year 0.47941525 year 0.62672150 year 0.746764100 year 0.875543 %\SDVV x Unmitigated Predeveloped Landuse Totals for BypassTotal Pervious Area: 1.16Total Impervious Area: 0.34 Mitigated Landuse Totals for BypassTotal Pervious Area:1.16Total Impervious Area: 0.34 Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Bypass.Return Period Flow(cfs)2 year 0.2766435 year 0.39966210 year 0.49033425 year 0.61555450 year 0.716705100 year 0.824725 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. 2005-2019; All Rights Reserved. Clear Creek Solutions, Inc.6200 Capitol Blvd. Ste FOlympia, WA. 98501Toll Free 1(866)943-0304Local (360)943-0304 www.clearcreeksolutions.com Appendix C – Critical Areas Report (Submitted as a separate report) Appendix D – Geotechnical Report (Submitted as a separate report) Appendix E – Arsenic and Lead Soil Assessment (Submitted as a separate report) Appendix F – Cultural Resources Report (Submitted as a separate report) Appendix G – Preliminary Tree Conservation Plan (Submitted as a separate report) Appendix H – Traffic Impact Analysis (Submitted as a separate report)