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HomeMy WebLinkAboutRS_Cascade Crest_Preliminary TIR 260713_v1 PRELIM TECHNICAL INFORMATION REPORT FOR Cascade Crest Apartments CITY OF RENTON, WASHINGTON Prepared by: Andrew Oh, P.E Approved by: Sheri H. Murata, P.E. Date: April 9, 2026 Revised: Core No.: 26005 4/9/26 Core Design, Inc. CASCADE CREST APARTMENTS i Cascade Crest Apartments Table of Contents 1. PROJECT OVERVIEW .......................................................................................................................... 1-1 Figure 1-1 Vicinity Map ..................................................................................................................... 1-1 2. CONDITIONS AND REQUIREMENTS SUMMARY ................................................................................ 2-2 2.1 Core Requirements .......................................................................................................................... 2-3 2.1.1 Core Requirement #1: Discharge at the Natural Location ...................................................... 2-3 2.1.2 Core Requirement #2: Offsite Analysis .................................................................................... 2-3 2.1.3 Core Requirement #3: Flow Control......................................................................................... 2-3 2.1.4 Core Requirement #4: Conveyance System ............................................................................. 2-3 2.1.5 Core Requirements #5: Erosion and Sediment Control ........................................................... 2-3 2.1.6 Core Requirement #6: Maintenance and Operations .............................................................. 2-3 2.1.7 Core Requirement #7: Financial Guarantees and Liability ....................................................... 2-3 2.1.8 Core Requirement #8: Water Quality ...................................................................................... 2-3 2.1.9 Core Requirement #9: On-Site BMPs ....................................................................................... 2-3 2.2 Special Requirements ...................................................................................................................... 2-3 2.2.1 Special Requirement #1: Other Adopted Area Specific Requirements .................................... 2-3 2.2.2 Special Requirement #2: Flood Hazard Area Delineation ........................................................ 2-3 2.2.3 Special Requirement #3: Flood Protection Facilities ................................................................ 2-3 2.2.4 Special Requirement #4: Source Control ................................................................................. 2-3 2.2.5 Special Requirement #5: Oil Control ........................................................................................ 2-4 2.2.6 Special Requirement #6: Aquifer Protection Area ................................................................... 2-4 3. OFFSITE ANALYSIS ............................................................................................................................. 3-1 Task 1 Study Area Definition and Maps ................................................................................................. 3-1 Task 2 Resource Review ........................................................................................................................ 3-1 Sensitive Areas Folio.......................................................................................................................... 3-1 Task 3 Field Investigation ...................................................................................................................... 3-1 Task 4 Drainage System Description and Problem Description ............................................................ 3-1 4. FLOW CONTROL AND WATER QUALITY ANALYSIS ............................................................................ 4-1 4.1 Predeveloped Site Hydrology .......................................................................................................... 4-1 Table 4-1A East Basin Predeveloped Conditions ............................................................................... 4-1 Core Design, Inc. CASCADE CREST APARTMENTS ii Table 4-1B West Basin Predeveloped Conditions ............................................................................. 4-1 4.2 Developed Site Hydrology ............................................................................................................... 4-2 Table 4-2A East Basin Developed Conditions .................................................................................... 4-2 Table 4-2B West Basin Developed Conditions .................................................................................. 4-2 4.3 Flow Control Analysis....................................................................................................................... 4-3 4.5 BMP Feasibility ................................................................................................................................ 4-5 4.6 Water Quality Treatment Analysis and Design ................................................................................ 4-7 Table 4-3A West Basin PGIS Areas .................................................................................................... 4-7 Table 4-3B East Basin PGIS Areas ...................................................................................................... 4-7 5. DOWNSTREAM CONVEYANCE SYSTEM CAPACITY ANALYSIS ............................................................ 5-1 6. SPECIAL REPORTS AND STUDIES ....................................................................................................... 6-1 7. OTHER PERMITS ................................................................................................................................ 7-1 8. ESC ANALYSIS AND DESIGN ............................................................................................................... 8-1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ............................. 9-1 9.1 Bond Quantities ............................................................................................................................... 9-1 10. OPERATIONS AND MAINTENANCE .................................................................................................. 10-1 Appendix A WWHM Report ..................................................................................................................... 10-2 Core Design, Inc. CASCADE CREST APARTMENTS Page 1-1 1. PROJECT OVERVIEW The proposed project is located at 3401 NE 12TH Street/1161 Olympia Avenue NE, Renton, WA. See Vicinity Map below. Figure 1-1 Vicinity Map The site is composed of a parcel numbers: 0923059124 and 0923059135 with an area of approximately 0.90 acres. The total site area, including frontage, is approximately 0.90 acres. The site is bordered by NE 12th Street to the north and Olympia Ave NE to the east. The site was previously developed with three single-story residential homes, driveways, and sheds. The project site is split into an east and west basin, with the east basin being a small portion of the project site and frontage. The proposed development of the property will include demolition of all hard surfaces located on site and the construction of 22 apartment units, parking lot, utilities, and frontage improvements. The subject project’s drainage facilities were designed using the guidelines and requirements established in Section 1.2.3.1 of the 2022 City of Renton Surface Water Design Manual (RSWDM). The Flow Control Duration Standard matching forested site conditions is required for this project. Core Design, Inc. CASCADE CREST APARTMENTS Page 2-2 2. CONDITIONS AND REQUIREMENTS SUMMARY The proposed project is classified as requiring “Full Drainage Review” per Page 1-8 Definitions given in the 2022 RSWDM. Therefore, all nine core requirements and six special requirements will be addressed per Section 1.2 and 1.3 of the 2022 RSWDM. Core Design, Inc. CASCADE CREST APARTMENTS Page 2-3 2.1 Core Requirements 2.1.1 Core Requirement #1: Discharge at the Natural Location The east basin drains to the east onto Olympia Avenue NE and south. The west basin flows to the low point on the site and leaves the site along the west border of the site onto neighboring properties. 2.1.2 Core Requirement #2: Offsite Analysis See Section 3 of this Report for the downstream drainage path. 2.1.3 Core Requirement #3: Flow Control The project will provide flow control as it proposes greater than 5,000 SF of impervious area. See Section 4 of this report for a detailed Flow Control Analysis. 2.1.4 Core Requirement #4: Conveyance System Conveyance calculations will be done during final engineering. 2.1.5 Core Requirements #5: Erosion and Sediment Control Erosion and Sediment control design will be provided during final engineering. 2.1.6 Core Requirement #6: Maintenance and Operations An Operations and Maintenance Manual will be provided in Section 10 during final engineering. 2.1.7 Core Requirement #7: Financial Guarantees and Liability Bond quantity will be provided during final engineering. 2.1.8 Core Requirement #8: Water Quality The project will provide water quality treatment. See Section 4.6 for details. 2.1.9 Core Requirement #9: On-Site BMPs The project site is greater than 22,000 square feet; this site falls under large Lot BMP Requirements. See Section 4.4 of this report for discussion on how this Core Requirement is addressed. 2.2 Special Requirements 2.2.1 Special Requirement #1: Other Adopted Area Specific Requirements There are no known additional requirements for the subject project. 2.2.2 Special Requirement #2: Flood Hazard Area Delineation Not applicable since the project does not contain nor is adjacent to a flood hazard area. 2.2.3 Special Requirement #3: Flood Protection Facilities Not applicable since the project does not rely on an existing flood protection facility or plans to modify or construct a new flood protection facility. 2.2.4 Special Requirement #4: Source Control This special requirement does not apply as the project does not require a commercial site development permit. Core Design, Inc. CASCADE CREST APARTMENTS Page 2-4 2.2.5 Special Requirement #5: Oil Control Not applicable since the project is not a high use site. The expected average daily traffic is less than 100 vehicles per 1,000 square feet of gross building area. 2.2.6 Special Requirement #6: Aquifer Protection Area Not applicable since the project is not in an Aquifer Protection Area. Core Design, Inc. CASCADE CREST APARTMENTS Page 3-1 3. OFFSITE ANALYSIS Task 1 Study Area Definition and Maps The proposed project is located within the Lower Cedar River drainage basin. Task 2 Resource Review Sensitive Areas Folio Renton GIS was reviewed for sensitive areas. The proposed project site does not fall within the following sensitive areas: coal mines, erosion hazard, flood hazard, floodway, channel migration zone, landslide, seismic hazard, regulated stream, wetland, or wellhead protection. Task 3 Field Investigation There is negligible upstream tributary area. Downstream Drainage Path East Basin Runoff from the east basin sheet flows east onto Olympic Avenue NE and flows south 300 feet to NE 11th Place before flowing east along NE 11th Place for an additional 300 feet. Runoff will then go north along Pierce Avenue NE and enter an existing drainage system that continues north and discharge at Honeydew Creek. West Basin Runoff from the west basin flows west along neighboring properties and into NE 12th Street for approximately 400 feet where it will then enter an existing storm system. Drainage continues west along NE 12th Street past the ¼ mile downstream mark. See the following page for a downstream route exhibit. Task 4 Drainage System Description and Problem Description Drainage complaints were researched within a quarter mile of the project site using the City of Renton’s GIS Map. There were no drainage complaints found. 9,028 752 WGS_1984_Web_Mercator_Auxiliary_Sphere Notes Legend 512 0 256 512 Feet All data, information, and maps are provided "as is" without warranty or any representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the user. None City and County Labels Parcels City and County Boundary Renton <all other values> Pump Station Pump Station ( Municipal - Surface Water Utility) Pump Station (Municipal - Other) Pump Station (Private) Discharge Point Discharge Point (Municipal - Surface Water Utility) Discharge Point (Municipal - Other) Discharge Point (Private) Pipe Pipe (Municipal - Surface Water Utility) Pipe (Municipal - Other) Pipe (Private) Open Drain Facility Outline Vegetated Non-Vegetated Facility Transfer Inactive Pipe Inactive Discharge Point Drainage Complaints Known Drainage Issues Renton King County 2023.sid Red: Band_1 Green: Band_2 Blue: Band_3 Core Design, Inc. CASCADE CREST APARTMENTS Page 4-1 4. FLOW CONTROL AND WATER QUALITY ANALYSIS The project site is proposing greater than 5,000 SF of new plus replaced impervious surface. A water quality treatment facility is proposed as the project triggers requirements for water quality treatment as delineated in Section 4.5 of this report. 4.1 Predeveloped Site Hydrology The site was previously developed with three single-story residential homes. The rest of the site was left as landscaping and forest. The total disturbed area of the project site is approximately 0.90 acres and includes the site as well as frontage improvements. There is approximately 0.05 acres of existing roadway that will be undisturbed, but captured and sent to the flow control facility. See Figure 4-1 on the following pages for the predeveloped conditions exhibit. The impervious area in the predeveloped conditions is from the existing residence, driveway and sheds. The predeveloped areas are shown in the table below. Table 4-1A East Basin Predeveloped Conditions Ground Cover Area (SF) Area (Acres) Pervious 6,354 0.15 Total Basin 6,354 0.15 Table 4-1B West Basin Predeveloped Conditions Ground Cover Area (SF) Area (Acres) Existing ROW Impervious 299 0.01 Onsite Pervious 29,881 0.69 ROW Pervious 3,935 0.08 Total Basin 34,115 0.78 Core Design, Inc. CASCADE CREST APARTMENTS Page 4-2 4.2 Developed Site Hydrology The developed site will include the demolition of impervious surfaces that will be located on site and the construction of 22 apartment units, shared driveway, utilities, and frontage improvements along NE 12th Street and Olympia Avenue NE. The proposed impervious area used for stormwater design was determined using the zoning of the site (RMF) and the city’s municipal code. The maximum impervious coverage for a zoning of RMF is 75% of the lot. The maximum impervious area per zoning has been used for flow control and water quality sizing. The project is proposing a shared access driveway for both lots. The project will be collecting 0.05 Acres of upstream existing impervious area from NE 12th Street and this area will be used as a treatment trade for the 0.05 Acres of proposed frontage improvement area along NE 12th Street that cannot be collected and conveyed to the proposed stormwater facilities on site. The developed condition areas are shown in the table below. See Figure 4-2 on the following page for the developed conditions exhibit. The project has counted the exact amount of impervious area to be proposed in the east basin to determine whether the basin can be flow control exempt. The basin will be less than 5,000 SF of new/replaced impervious surface. To properly account for the max allowed impervious area of 75% of the entire site, the project has taken 75% of the entire site and subtracted the proposed impervious area from the east basin to get the impervious area to be modeled as part of the west basin flow control. Table 4-2A East Basin Developed Conditions Ground Cover Area (SF) Area (Acres) Pervious 3,470 0.08 Impervious 2,884 0.07 Total Basin 6,354 0.15 Table 4-2B West Basin Developed Conditions Ground Cover Area (SF) Area (Acres) Onsite Impervious 24,292 0.56 Onsite Pervious 5,589 0.13 ROW Impervious 3,233 0.07 ROW Pervious 1,001 0.02 Total Basin 34,115 0.78 Core Design, Inc. CASCADE CREST APARTMENTS Page 4-3 4.3 Flow Control Analysis Using the predeveloped and developed areas above, a 92’ x 20’ Vault with 8.5’ of live storage was sized. The vault requires 13,721 CF for sufficient capacity and will be designed to provide a minimum of 13,721 CF. Below are the Vault details and flow rates. The full WWHM report can be found in Appendix A. WWWWW DEC-8 / 7 / 5 " DEC-1 9 " P-14" P-23"P-15" C-7" DEC-2 5 " F-48" DEC-9 " B-6" DEC-2 4 " F-37" DEC-4 X 6 " AP-12 / 1 2 / 1 1 " AP-19 " DEC-9 " DEC-3 4 " C C MB MB MB MB C C C /// /// /// /// /// //////////// / / / /// ////// /// /// /// /// /// /// /// /// / / / XX X X X X X X XX X X X X X X X X X X X X X X X X X X XX CM G G G G G G GGGGGGGGCM CM CM CM CM CM CM CM CM CM CM / // /// / / / /// // / /// /// ////// /// /// / // ///// / /// /// / // /// /// /// // / // / O H P T O H P T OH P T OH P T OH P T OH P T OH P T OHPTOHPTOHPTOHPTOHPTOHPTOHPTOHP OH P T OHPT OH P T OH P T OH P T O H P T OH P T OH P T OH P T OH P T // / /// SS SS SS SS SS SS SS SS SS SS SS SS SD SD SD SD SD SD SD ?? WWWWW WWWW WWW WWWWWWWW W W W W W W W W W W W N88°00'31"W 134.10 N88°00'31"W 105.08 N0 0 ° 1 3 ' 4 8 " W 1 2 1 . 9 9 N0 0 ° 1 3 ' 4 8 " W 1 2 1 . 9 9 N0 0 ° 1 3 ' 4 8 " W 1 8 6 . 9 4 N88°00'28"W 124.09 N0 0 ° 1 3 ' 4 8 " W 1 1 5 . 0 9 N0 0 ° 1 3 ' 4 8 " W 3 0 2 . 0 2 N88°00'28"W 10.01 OHPT NE 12TH STREET OL Y M P I A A V E N U E N E TPN: 092305-9135 FRANK YE 1161 OLYMPIA AVENUE NE RENTON 98056 (PARCEL A)TPN: 092305-9124 FRANK YE 3401 NE 12TH STREET RENTON 98056 (PARCEL B) TPN: 0923 0 5 - 9 1 7 3 OBRIEN 3327 NE 1 2 T H S T R E E T RENTON 9 8 0 5 6 TPN: 09230 5 - 9 1 9 4 RENTON G R E E N S PORTFOL I O L L C 1151 OLYM P I A A V E N E RENTON 9 8 0 5 6 SITE BENCHMARK EL=438.81 N88°00'28"W 105.08 EAST/WEST BASIN BREAK LINE (PURPLE) EXISTING BASIN BOUNDARY (GREEN) 4/ 9 / 2 0 2 6 1 1 : 3 5 A M MS T E F A N S S O N J: \ 2 0 2 6 \ 2 6 0 0 5 \ E N G I N E E R I N G \ E X H I B I T S \ D R A I N A G E R E P O R T \ E X I S T I N G C O N D I T I O N E X H I B I T . D W G LA Y O U T 1 DESIGN E N G I N E E R I N G P L A N N I N G S U R V E Y I N G 12 1 0 0 N E 1 9 5 t h S t , S u i t e 3 0 0 Bo t h e l l , W a s h i n g t o n 9 8 0 1 1 42 5 . 8 8 5 . 7 8 7 7 F a x 4 2 5 . 8 8 5 . 7 9 6 3 E X I S T I N G C O N D I T I O N S E X H I B I T C A S C A D E C R E S T - R E N T O N 22+00 23+00 24+00 25+00 26+00 27+00 28+0028+01 32 + 0 0 33 + 0 0 34 + 0 0 35 + 0 0 1+ 0 0 2+ 0 0 2+ 5 0 10+00 11+00 4 3 8 440 438 440 442 440 SD 4 3 0 440 44 0 4 2 8 4 3 2 4 3 4 4 3 6 4 3 8 SDSD SD SD SD SDSDSDSD SD SD /// /// /// /// /// //////////// / / / /// ////// /// /// /// /// /// /// /// /// / / / // / /// /// // / /// SD SD SD NE 12TH STREET OL Y M P I A A V E N U E N E TPN: 0923 0 5 - 9 1 7 3 OBRIEN 33 27 NE 1 2T H S T RE E RENTON 9 8 0 5 6 TPN: 09230 5 - 9 1 9 4 RENTON G R E E N S PORTFOL I O L L C 1151 OLYM P I A A V E N E RENTON 9 8 0 5 6 PROPOSED DETENTION VAULT PROPOSED MODULAR WETLAND UNIT OR APPROVED EQUAL UPSTREAM TREATMENT TRADE AREA COLLECTED 0.05 AC (BLUE) PROPOSED FRONTAGE IMPROVEMENT TREATMENT TRADE AREA NOT COLLECTED 0.05 AC (RED) EAST/WEST BASIN BREAK LINE (PURPLE) DEVELOPED BASIN BOUNDARY (GREEN) 4/ 1 3 / 2 0 2 6 4 : 0 5 P M MS T E F A N S S O N J: \ 2 0 2 6 \ 2 6 0 0 5 \ E N G I N E E R I N G \ E X H I B I T S \ D R A I N A G E R E P O R T \ D E V E L O P E D C O N D I T I O N E X H I B I T . D W G LA Y O U T 1 DESIGN E N G I N E E R I N G P L A N N I N G S U R V E Y I N G 12 1 0 0 N E 1 9 5 t h S t , S u i t e 3 0 0 Bo t h e l l , W a s h i n g t o n 9 8 0 1 1 42 5 . 8 8 5 . 7 8 7 7 F a x 4 2 5 . 8 8 5 . 7 9 6 3 D E V E L O P E D C O N D I T I O N S E X H I B I T C A S C A D E C R E S T - R E N T O N Core Design, Inc. CASCADE CREST APARTMENTS Page 4-5 4.5 BMP Feasibility Per Section 1.2.9.1 in the RSWDM, projects subject to Core Requirement #9 must apply on-site BMPs to either supplement the flow mitigation provided by required flow control facilities or provide flow mitigation where flow control facilities are not required. On-site BMPs must be implemented per the requirements and approach detailed in Sections 1.2.9.2 and 1.2.9.3 for individual lots and subdivisions or road improvement projects, respectively. The Section applicable to this project is Section 1.2.9.2. Per Section 1.2.9.2, projects on individual sites/lots, on-site BMPs must be selected and applied according to the individual lot BMP requirements. The project site is larger than 22,000 square feet and follows requirements specified in Section 1.2.9.2.2 Large Lot BMP Requirements of the 2017 RSWDM. 1. The feasibility and applicability of full dispersion as detailed in Appendix C, Section C.2.1 must be evaluated for all target impervious surfaces. If feasible and applicable, full dispersion must be implemented as part of the proposed project. Typically, large lot full dispersion will be applicable only in subdivisions where enough forest was preserved by tract, easement, or covenant to meet the minimum requirements for full dispersion in Appendix C, Section C.2.1.1 Full dispersion is not feasible due to non-existent native forested area. 2. Where full dispersion of target impervious roof areas is not feasible or applicable, or will cause flooding or erosion impacts, the feasibility and applicability of full infiltration as detailed in Appendix C, Section C.2.2 must be evaluated (note, this will require a soils report for the site/lot). If feasible and applicable, full infiltration of roof runoff must be implemented as part of the proposed project. As per the Geotechnical evaluation by Cobalt Geosciences dated March 13, 2026, “Infiltration is not feasible due to the presence of extensive fill and dense glacial till.” 3. All target impervious surfaces not mitigated by Requirements 1 and 2 above, must be mitigated to the maximum extent feasible using one or more BMPs from the following list. Use of a given BMP is subject to evaluation of its feasibility and applicability as detailed in Appendix C. Feasible BMPs are required to be implemented. The BMPs listed below may be located anywhere on the site/lot subject to the limitations and design specifications for each BMP. These BMPs must be implemented as part of the proposed project. • Full Infiltration per Appendix C, Section C.2.2, or per Section 5.2, whichever is applicable As per the Geotechnical evaluation by Cobalt Geosciences dated March 13, 2026, “Infiltration is not feasible due to the presence of extensive fill and dense glacial till.” • Limited Infiltration per Appendix C, Section C.2.3, As per the Geotechnical evaluation by Cobalt Geosciences dated March 13, 2026, “Infiltration is not feasible due to the presence of extensive fill and dense glacial till.” • Rain Gardens/Bioretention per Appendix C, Section C.2.6 and C.2.12 12 Core Design, Inc. CASCADE CREST APARTMENTS Page 4-6 As per the Geotechnical evaluation by Cobalt Geosciences dated March 13, 2026, “Infiltration is not feasible due to the presence of extensive fill and dense glacial till.” • Permeable Pavement per Appendix C, Section C.2.7 The project is proposing approximately 1,039 SF of pervious pavers. 4. All target impervious surfaces not mitigated by Requirements 1, 2 and 3 above, must be mitigated to the maximum extent feasible using the Basic Dispersion BMP described below. Use of Basic Dispersion is subject to evaluation of its feasibility and applicability as detailed in Appendix C. Feasible BMPs are required to be implemented. Basic Dispersion BMPs may be located anywhere on the site/lot subject to the limitations and design specifications cited in Appendix C. The BMP must be implemented as part of the proposed project. • Basic Dispersion per Appendix C, Section C.2.4, The project is proposing four splashblocks to provide basic dispersion for proposed roof areas. Each splashblock can handle a max of 700 SF of impervious area for a total of 2,800 SF 5. BMPs must be implemented, at minimum, for an impervious area equal to 20% of target impervious surfaces of to an impervious area equal to 10% of the site/lot, whichever is less if the total impervious surface coverage is greater than 65%. The project is proposing 75% of impervious area. The project will need to provide a minimum of 3,624 SF of BMPs. Per the mentioned BMPs above, the project will provide BMPs for 3,839 SF of impervious surfaces. • Reduced Impervious Surface Credit per Appendix C, Section C.2.9 This BMP will be evaluated with the building permit. • Native Growth Retention Credit per Appendix C, Section C.2.10. This BMP is not applicable to the project since there is no forested area to retain. 6. The soil moisture holding capacity of new pervious surfaces (target pervious surfaces) must be protected in accordance with the soil amendment BMP as detailed in Appendix C, Section C.2.13. Soil amendment will be incorporated for disturbed areas not covered with hard surfaces. Core Design, Inc. CASCADE CREST APARTMENTS Page 4-7 4.6 Water Quality Treatment Analysis and Design The subject project exceeds 5,000 SF of PGIS in the west basin and does not for the east basin. Therefore enhanced basic water quality treatment is required only for the west basin. See Table 4-3 below for an area breakdown. This project will utilize a modular wetland system (or approved equal) located downstream of the detention vault to provide water quality treatment. Detailed sizing and design of the Modular Wetland System will be provided during final engineering design. Table 4-3A West Basin PGIS Areas Ground Cover Area (SF) Onsite Shared Driveway 12,432 ROW PGIS 406 Total Area 12,838 Table 4-3B East Basin PGIS Areas Ground Cover Area (SF) ROW PGIS 465 Total Area 465 Core Design, Inc. CASCADE CREST APARTMENTS Page 5-1 5. DOWNSTREAM CONVEYANCE SYSTEM CAPACITY ANALYSIS Conveyance Analysis will be provided with final engineering. Core Design, Inc. CASCADE CREST APARTMENTS Page 6-1 6. SPECIAL REPORTS AND STUDIES The following reports and assessments are provided for reference and informational purposes only. Core Design takes no responsibility or liability for these reports, assessments or designs as they were not completed under the direct supervision of Core Design. ➢ Geotechnical Evaluation March 13, 2026 Cobalt Geosciences, LLC P.O Box 82243 Kenmore, WA 98028 206-331-1097 ➢ Arborist Report March 18, 2026 Greenforest Incorporated 4547 S. Lucile St. Seattle, WA 98118 206-723-0656 Core Design, Inc. CASCADE CREST APARTMENTS Page 7-1 7. OTHER PERMITS Core Design, Inc. CASCADE CREST APARTMENTS Page 8-1 8. ESC ANALYSIS AND DESIGN ESC analysis and design will be provided during final engineering. Core Design, Inc. CASCADE CREST APARTMENTS Page 9-1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 Bond Quantities The City of Renton Bond Quantity Worksheet will be provided with Final Engineering. Core Design, Inc. CASCADE CREST APARTMENTS Page 10-1 10. OPERATIONS AND MAINTENANCE The operations and maintenance manual will be provided with final engineering. Core Design, Inc. CASCADE CREST APARTMENTS Page 10-2 Appendix A WWHM Report WWHM2012 PROJECT REPORT Detention Facility 4/9/2026 1:08:38 AM Page 2 General Model Information WWHM2012 Project Name:Detention Facility Site Name: Site Address: City: Report Date:4/9/2026 Gage:Seatac Data Start:1948/10/01 Data End:2009/09/30 Timestep:15 Minute Precip Scale:1.000 Version Date:2025/09/16 Version:4.3.2 POC Thresholds Low Flow Threshold for POC1:50 Percent of the 2 Year High Flow Threshold for POC1:50 Year Detention Facility 4/9/2026 1:08:38 AM Page 3 Landuse Basin Data Predeveloped Land Use Onsite Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 0.69 Pervious Total 0.69 Impervious Land Use acre Impervious Total 0 Basin Total 0.69 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Detention Facility 4/9/2026 1:08:38 AM Page 4 ROW Bypass:No GroundWater:No Pervious Land Use acre C, Forest, Mod 0.08 Pervious Total 0.08 Impervious Land Use acre ROADS MOD 0.01 Impervious Total 0.01 Basin Total 0.09 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: POC 1 POC 1 Detention Facility 4/9/2026 1:08:38 AM Page 5 Mitigated Land Use Onsite Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.13 Pervious Total 0.13 Impervious Land Use acre ROOF TOPS FLAT 0.56 Impervious Total 0.56 Basin Total 0.69 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Vault 1 Vault 1 Detention Facility 4/9/2026 1:08:38 AM Page 6 ROW Bypass:No GroundWater:No Pervious Land Use acre C, Lawn, Mod 0.02 Pervious Total 0.02 Impervious Land Use acre ROADS MOD 0.07 Impervious Total 0.07 Basin Total 0.09 Element Flow Componants: Surface Interflow Groundwater Componant Flows To: Vault 1 Vault 1POC 1POC 1 Detention Facility 4/9/2026 1:08:38 AM Page 7 Routing Elements Predeveloped Routing Detention Facility 4/9/2026 1:08:38 AM Page 8 Mitigated Routing Vault 1 Width:20 ft. Length:92 ft. Depth:8.5 ft. Discharge Structure Riser Height:7.5 ft. Riser Diameter:12 in. Orifice 1 Diameter:0.438 in.Elevation:0 ft. Orifice 2 Diameter:0.750 in.Elevation:4.65 ft. Orifice 3 Diameter:0.625 in.Elevation:6.1 ft. Element Outlets: Outlet 1 Outlet 2 Outlet Flows To: Vault Hydraulic Table Stage(feet)Area(ac.)Volume(ac-ft.)Discharge(cfs)Infilt(cfs) 0.0000 0.042 0.000 0.000 0.000 0.0944 0.042 0.004 0.001 0.000 0.1889 0.042 0.008 0.002 0.000 0.2833 0.042 0.012 0.002 0.000 0.3778 0.042 0.016 0.003 0.000 0.4722 0.042 0.019 0.003 0.000 0.5667 0.042 0.023 0.003 0.000 0.6611 0.042 0.027 0.004 0.000 0.7556 0.042 0.031 0.004 0.000 0.8500 0.042 0.035 0.004 0.000 0.9444 0.042 0.039 0.005 0.000 1.0389 0.042 0.043 0.005 0.000 1.1333 0.042 0.047 0.005 0.000 1.2278 0.042 0.051 0.005 0.000 1.3222 0.042 0.055 0.006 0.000 1.4167 0.042 0.059 0.006 0.000 1.5111 0.042 0.063 0.006 0.000 1.6056 0.042 0.067 0.006 0.000 1.7000 0.042 0.071 0.006 0.000 1.7944 0.042 0.075 0.007 0.000 1.8889 0.042 0.079 0.007 0.000 1.9833 0.042 0.083 0.007 0.000 2.0778 0.042 0.087 0.007 0.000 2.1722 0.042 0.091 0.007 0.000 2.2667 0.042 0.095 0.007 0.000 2.3611 0.042 0.099 0.008 0.000 2.4556 0.042 0.103 0.008 0.000 2.5500 0.042 0.107 0.008 0.000 2.6444 0.042 0.111 0.008 0.000 2.7389 0.042 0.115 0.008 0.000 2.8333 0.042 0.119 0.008 0.000 2.9278 0.042 0.123 0.008 0.000 3.0222 0.042 0.127 0.009 0.000 3.1167 0.042 0.131 0.009 0.000 3.2111 0.042 0.135 0.009 0.000 3.3056 0.042 0.139 0.009 0.000 3.4000 0.042 0.143 0.009 0.000 Detention Facility 4/9/2026 1:08:38 AM Page 9 3.4944 0.042 0.147 0.009 0.000 3.5889 0.042 0.151 0.009 0.000 3.6833 0.042 0.155 0.010 0.000 3.7778 0.042 0.159 0.010 0.000 3.8722 0.042 0.163 0.010 0.000 3.9667 0.042 0.167 0.010 0.000 4.0611 0.042 0.171 0.010 0.000 4.1556 0.042 0.175 0.010 0.000 4.2500 0.042 0.179 0.010 0.000 4.3444 0.042 0.183 0.010 0.000 4.4389 0.042 0.187 0.010 0.000 4.5333 0.042 0.191 0.011 0.000 4.6278 0.042 0.195 0.011 0.000 4.7222 0.042 0.199 0.015 0.000 4.8167 0.042 0.203 0.017 0.000 4.9111 0.042 0.207 0.019 0.000 5.0056 0.042 0.211 0.020 0.000 5.1000 0.042 0.215 0.022 0.000 5.1944 0.042 0.219 0.023 0.000 5.2889 0.042 0.223 0.024 0.000 5.3833 0.042 0.227 0.025 0.000 5.4778 0.042 0.231 0.026 0.000 5.5722 0.042 0.235 0.026 0.000 5.6667 0.042 0.239 0.027 0.000 5.7611 0.042 0.243 0.028 0.000 5.8556 0.042 0.247 0.029 0.000 5.9500 0.042 0.251 0.030 0.000 6.0444 0.042 0.255 0.030 0.000 6.1389 0.042 0.259 0.033 0.000 6.2333 0.042 0.263 0.036 0.000 6.3278 0.042 0.267 0.037 0.000 6.4222 0.042 0.271 0.039 0.000 6.5167 0.042 0.275 0.041 0.000 6.6111 0.042 0.279 0.042 0.000 6.7056 0.042 0.283 0.043 0.000 6.8000 0.042 0.287 0.044 0.000 6.8944 0.042 0.291 0.046 0.000 6.9889 0.042 0.295 0.047 0.000 7.0833 0.042 0.299 0.048 0.000 7.1778 0.042 0.303 0.049 0.000 7.2722 0.042 0.307 0.050 0.000 7.3667 0.042 0.311 0.051 0.000 7.4611 0.042 0.315 0.052 0.000 7.5556 0.042 0.319 0.191 0.000 7.6500 0.042 0.323 0.658 0.000 7.7444 0.042 0.327 1.238 0.000 7.8389 0.042 0.331 1.766 0.000 7.9333 0.042 0.335 2.116 0.000 8.0278 0.042 0.339 2.345 0.000 8.1222 0.042 0.343 2.542 0.000 8.2167 0.042 0.347 2.725 0.000 8.3111 0.042 0.351 2.896 0.000 8.4056 0.042 0.355 3.057 0.000 8.5000 0.042 0.359 3.211 0.000 8.5944 0.042 0.363 3.357 0.000 8.6889 0.000 0.000 3.497 0.000 Detention Facility 4/9/2026 1:08:38 AM Page 10 Analysis Results POC 1 + Predeveloped x Mitigated Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.77 Total Impervious Area:0.01 Mitigated Landuse Totals for POC #1 Total Pervious Area:0.15 Total Impervious Area:0.63 Flow Frequency Method:Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.025034 5 year 0.040429 10 year 0.051379 25 year 0.06581 50 year 0.076884 100 year 0.088173 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.014234 5 year 0.023591 10 year 0.031585 25 year 0.044057 50 year 0.055288 100 year 0.068378 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.032 0.009 1950 0.036 0.016 1951 0.052 0.044 1952 0.018 0.008 1953 0.014 0.016 1954 0.020 0.010 1955 0.033 0.010 1956 0.028 0.027 1957 0.024 0.010 1958 0.024 0.011 Detention Facility 4/9/2026 1:09:23 AM Page 11 1959 0.020 0.010 1960 0.038 0.029 1961 0.020 0.020 1962 0.013 0.009 1963 0.017 0.011 1964 0.026 0.020 1965 0.019 0.022 1966 0.016 0.010 1967 0.040 0.014 1968 0.024 0.010 1969 0.023 0.010 1970 0.018 0.011 1971 0.021 0.011 1972 0.040 0.034 1973 0.018 0.022 1974 0.022 0.010 1975 0.030 0.010 1976 0.022 0.010 1977 0.006 0.009 1978 0.018 0.011 1979 0.010 0.008 1980 0.052 0.033 1981 0.015 0.010 1982 0.035 0.027 1983 0.027 0.010 1984 0.017 0.009 1985 0.009 0.009 1986 0.041 0.011 1987 0.038 0.028 1988 0.015 0.010 1989 0.011 0.009 1990 0.090 0.030 1991 0.050 0.034 1992 0.021 0.011 1993 0.019 0.008 1994 0.008 0.008 1995 0.026 0.020 1996 0.063 0.041 1997 0.047 0.040 1998 0.015 0.009 1999 0.055 0.033 2000 0.019 0.011 2001 0.006 0.007 2002 0.024 0.016 2003 0.036 0.010 2004 0.036 0.042 2005 0.027 0.010 2006 0.029 0.025 2007 0.069 0.051 2008 0.082 0.035 2009 0.040 0.022 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0901 0.0514 2 0.0820 0.0436 3 0.0693 0.0419 Detention Facility 4/9/2026 1:09:23 AM Page 12 4 0.0627 0.0408 5 0.0550 0.0395 6 0.0522 0.0351 7 0.0516 0.0343 8 0.0499 0.0337 9 0.0471 0.0326 10 0.0413 0.0326 11 0.0403 0.0301 12 0.0402 0.0294 13 0.0399 0.0281 14 0.0384 0.0270 15 0.0378 0.0268 16 0.0365 0.0254 17 0.0358 0.0224 18 0.0355 0.0224 19 0.0346 0.0223 20 0.0330 0.0203 21 0.0320 0.0198 22 0.0302 0.0196 23 0.0294 0.0164 24 0.0278 0.0157 25 0.0273 0.0155 26 0.0272 0.0143 27 0.0263 0.0111 28 0.0257 0.0111 29 0.0244 0.0111 30 0.0239 0.0111 31 0.0237 0.0109 32 0.0236 0.0108 33 0.0225 0.0107 34 0.0223 0.0106 35 0.0220 0.0104 36 0.0213 0.0104 37 0.0211 0.0104 38 0.0204 0.0104 39 0.0201 0.0102 40 0.0199 0.0102 41 0.0192 0.0101 42 0.0188 0.0099 43 0.0185 0.0099 44 0.0183 0.0098 45 0.0180 0.0098 46 0.0179 0.0098 47 0.0176 0.0097 48 0.0174 0.0096 49 0.0166 0.0095 50 0.0163 0.0094 51 0.0153 0.0089 52 0.0150 0.0089 53 0.0148 0.0088 54 0.0140 0.0087 55 0.0129 0.0087 56 0.0109 0.0086 57 0.0103 0.0085 58 0.0095 0.0085 59 0.0079 0.0078 60 0.0056 0.0076 61 0.0056 0.0071 Detention Facility 4/9/2026 1:09:23 AM Page 13 Detention Facility 4/9/2026 1:09:23 AM Page 14 Duration Flows The Facility PASSED Flow(cfs)Predev Mit Percentage Pass/Fail 0.0125 14970 7415 49 Pass 0.0132 13421 7157 53 Pass 0.0138 11986 6904 57 Pass 0.0145 10694 6669 62 Pass 0.0151 9625 6468 67 Pass 0.0158 8692 6203 71 Pass 0.0164 7880 5925 75 Pass 0.0171 7078 5653 79 Pass 0.0177 6412 5322 83 Pass 0.0184 5852 4999 85 Pass 0.0190 5339 4667 87 Pass 0.0197 4898 4336 88 Pass 0.0203 4502 4038 89 Pass 0.0210 4107 3762 91 Pass 0.0216 3769 3480 92 Pass 0.0223 3454 3221 93 Pass 0.0229 3185 2967 93 Pass 0.0236 2930 2738 93 Pass 0.0242 2691 2507 93 Pass 0.0249 2455 2269 92 Pass 0.0255 2233 2019 90 Pass 0.0262 2053 1822 88 Pass 0.0268 1858 1615 86 Pass 0.0275 1698 1446 85 Pass 0.0281 1571 1292 82 Pass 0.0288 1422 1138 80 Pass 0.0294 1293 986 76 Pass 0.0301 1183 809 68 Pass 0.0307 1096 623 56 Pass 0.0314 1007 566 56 Pass 0.0320 936 512 54 Pass 0.0327 872 447 51 Pass 0.0333 808 414 51 Pass 0.0340 746 381 51 Pass 0.0346 691 356 51 Pass 0.0353 647 337 52 Pass 0.0359 591 324 54 Pass 0.0366 541 312 57 Pass 0.0372 494 294 59 Pass 0.0379 443 277 62 Pass 0.0385 399 258 64 Pass 0.0392 358 232 64 Pass 0.0398 319 203 63 Pass 0.0405 290 184 63 Pass 0.0411 258 157 60 Pass 0.0418 232 139 59 Pass 0.0424 209 127 60 Pass 0.0431 180 116 64 Pass 0.0437 155 103 66 Pass 0.0444 135 91 67 Pass 0.0450 120 83 69 Pass 0.0457 109 74 67 Pass 0.0463 96 65 67 Pass Detention Facility 4/9/2026 1:09:23 AM Page 15 0.0470 86 59 68 Pass 0.0476 72 54 75 Pass 0.0483 62 47 75 Pass 0.0489 50 42 84 Pass 0.0496 46 37 80 Pass 0.0502 40 30 75 Pass 0.0509 32 17 53 Pass 0.0515 28 0 0 Pass 0.0522 24 0 0 Pass 0.0528 19 0 0 Pass 0.0535 16 0 0 Pass 0.0541 14 0 0 Pass 0.0548 13 0 0 Pass 0.0554 9 0 0 Pass 0.0561 8 0 0 Pass 0.0567 7 0 0 Pass 0.0574 7 0 0 Pass 0.0580 7 0 0 Pass 0.0587 7 0 0 Pass 0.0593 7 0 0 Pass 0.0600 7 0 0 Pass 0.0606 7 0 0 Pass 0.0613 6 0 0 Pass 0.0619 6 0 0 Pass 0.0626 6 0 0 Pass 0.0632 5 0 0 Pass 0.0639 5 0 0 Pass 0.0645 5 0 0 Pass 0.0652 5 0 0 Pass 0.0658 5 0 0 Pass 0.0665 5 0 0 Pass 0.0671 5 0 0 Pass 0.0678 5 0 0 Pass 0.0684 4 0 0 Pass 0.0691 4 0 0 Pass 0.0697 3 0 0 Pass 0.0704 3 0 0 Pass 0.0710 3 0 0 Pass 0.0717 3 0 0 Pass 0.0723 3 0 0 Pass 0.0730 3 0 0 Pass 0.0736 3 0 0 Pass 0.0743 3 0 0 Pass 0.0749 3 0 0 Pass 0.0756 3 0 0 Pass 0.0762 3 0 0 Pass 0.0769 3 0 0 Pass Detention Facility 4/9/2026 1:09:23 AM Page 16 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume:0 acre-feet On-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Off-line facility target flow:0 cfs. Adjusted for 15 min:0 cfs. Detention Facility 4/9/2026 1:09:23 AM Page 17 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. Detention Facility 4/9/2026 1:09:23 AM Page 18 Appendix Predeveloped Schematic Detention Facility 4/9/2026 1:09:25 AM Page 19 Mitigated Schematic Detention Facility 4/9/2026 1:09:26 AM Page 20 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 Detention Facility.wdm MESSU 25 PreDetention Facility.MES 27 PreDetention Facility.L61 28 PreDetention Facility.L62 30 POCDetention Facility1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 11 IMPLND 2 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<----------Title----------->***TRAN PIVL DIG1 FIL1 PYR DIG2 FIL2 YRND 1 Onsite 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 Detention Facility 4/9/2026 1:09:26 AM Page 21 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 *** 2 ROADS/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 2 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 2 0 0 4 0 0 4 1 9 END PRINT-INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 2 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 2 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 2 0 0 Detention Facility 4/9/2026 1:09:26 AM Page 22 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 2 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Onsite*** PERLND 11 0.69 COPY 501 12 PERLND 11 0.69 COPY 501 13 ROW*** PERLND 11 0.08 COPY 501 12 PERLND 11 0.08 COPY 501 13 IMPLND 2 0.01 COPY 501 15 ******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 Detention Facility 4/9/2026 1:09:26 AM Page 23 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 MASS-LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS-LINK 15 END MASS-LINK END RUN Detention Facility 4/9/2026 1:09:26 AM Page 24 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 Detention Facility.wdm MESSU 25 MitDetention Facility.MES 27 MitDetention Facility.L61 28 MitDetention Facility.L62 30 POCDetention Facility1.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 17 IMPLND 4 IMPLND 2 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 Vault 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 *** 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 *** 17 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT-INFO <PLS > ***************** Print-flags ***************************** PIVL PYR Detention Facility 4/9/2026 1:09:26 AM Page 25 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 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 *** 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 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 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 *** 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 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 *** 4 ROOF TOPS/FLAT 1 1 1 27 0 2 ROADS/MOD 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 4 0 0 1 0 0 0 2 0 0 1 0 0 0 END ACTIVITY PRINT-INFO <ILS > ******** Print-flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 4 0 0 4 0 0 4 1 9 2 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 *** 4 0 0 0 0 0 2 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC Detention Facility 4/9/2026 1:09:26 AM Page 26 4 400 0.01 0.1 0.1 2 400 0.05 0.1 0.08 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 4 0 0 2 0 0 END IWAT-PARM3 IWAT-STATE1 <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 4 0 0 2 0 0 END IWAT-STATE1 END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Onsite*** PERLND 17 0.13 RCHRES 1 2 PERLND 17 0.13 RCHRES 1 3 IMPLND 4 0.56 RCHRES 1 5 ROW*** PERLND 17 0.02 RCHRES 1 2 PERLND 17 0.02 RCHRES 1 3 IMPLND 2 0.07 RCHRES 1 5 ******Routing****** PERLND 17 0.13 COPY 1 12 IMPLND 4 0.56 COPY 1 15 PERLND 17 0.13 COPY 1 13 PERLND 17 0.02 COPY 1 12 IMPLND 2 0.07 COPY 1 15 PERLND 17 0.02 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 Vault 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 Detention Facility 4/9/2026 1:09:26 AM Page 27 # - # 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 0.02 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 92 4 Depth Area Volume Outflow1 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (ft/sec) (Minutes)*** 0.000000 0.042241 0.000000 0.000000 0.094444 0.042241 0.003989 0.001596 0.188889 0.042241 0.007979 0.002257 0.283333 0.042241 0.011968 0.002765 0.377778 0.042241 0.015958 0.003193 0.472222 0.042241 0.019947 0.003569 0.566667 0.042241 0.023936 0.003910 0.661111 0.042241 0.027926 0.004223 0.755556 0.042241 0.031915 0.004515 0.850000 0.042241 0.035904 0.004789 0.944444 0.042241 0.039894 0.005048 1.038889 0.042241 0.043883 0.005294 1.133333 0.042241 0.047873 0.005530 1.227778 0.042241 0.051862 0.005755 1.322222 0.042241 0.055851 0.005973 1.416667 0.042241 0.059841 0.006182 1.511111 0.042241 0.063830 0.006385 1.605556 0.042241 0.067820 0.006582 1.700000 0.042241 0.071809 0.006772 1.794444 0.042241 0.075798 0.006958 1.888889 0.042241 0.079788 0.007139 1.983333 0.042241 0.083777 0.007315 2.077778 0.042241 0.087767 0.007487 2.172222 0.042241 0.091756 0.007655 2.266667 0.042241 0.095745 0.007820 2.361111 0.042241 0.099735 0.007981 2.455556 0.042241 0.103724 0.008139 2.550000 0.042241 0.107713 0.008294 2.644444 0.042241 0.111703 0.008447 2.738889 0.042241 0.115692 0.008596 2.833333 0.042241 0.119682 0.008743 2.927778 0.042241 0.123671 0.008888 3.022222 0.042241 0.127660 0.009030 3.116667 0.042241 0.131650 0.009170 3.211111 0.042241 0.135639 0.009308 3.305556 0.042241 0.139629 0.009444 3.400000 0.042241 0.143618 0.009578 Detention Facility 4/9/2026 1:09:26 AM Page 28 3.494444 0.042241 0.147607 0.009710 3.588889 0.042241 0.151597 0.009840 3.683333 0.042241 0.155586 0.009969 3.777778 0.042241 0.159576 0.010096 3.872222 0.042241 0.163565 0.010221 3.966667 0.042241 0.167554 0.010345 4.061111 0.042241 0.171544 0.010467 4.155556 0.042241 0.175533 0.010588 4.250000 0.042241 0.179522 0.010708 4.344444 0.042241 0.183512 0.010826 4.438889 0.042241 0.187501 0.010943 4.533333 0.042241 0.191491 0.011059 4.627778 0.042241 0.195480 0.011174 4.722222 0.042241 0.199469 0.015389 4.816667 0.042241 0.203459 0.017631 4.911111 0.042241 0.207448 0.019311 5.005556 0.042241 0.211438 0.020723 5.100000 0.042241 0.215427 0.021970 5.194444 0.042241 0.219416 0.023101 5.288889 0.042241 0.223406 0.024146 5.383333 0.042241 0.227395 0.025123 5.477778 0.042241 0.231385 0.026045 5.572222 0.042241 0.235374 0.026920 5.666667 0.042241 0.239363 0.027756 5.761111 0.042241 0.243353 0.028557 5.855556 0.042241 0.247342 0.029329 5.950000 0.042241 0.251331 0.030074 6.044444 0.042241 0.255321 0.030795 6.138889 0.042241 0.259310 0.033586 6.233333 0.042241 0.263300 0.036046 6.327778 0.042241 0.267289 0.037897 6.422222 0.042241 0.271278 0.039501 6.516667 0.042241 0.275268 0.040957 6.611111 0.042241 0.279257 0.042310 6.705556 0.042241 0.283247 0.043584 6.800000 0.042241 0.287236 0.044796 6.894444 0.042241 0.291225 0.045955 6.988889 0.042241 0.295215 0.047070 7.083333 0.042241 0.299204 0.048147 7.177778 0.042241 0.303194 0.049190 7.272222 0.042241 0.307183 0.050202 7.366667 0.042241 0.311172 0.051187 7.461111 0.042241 0.315162 0.052148 7.555556 0.042241 0.319151 0.191814 7.650000 0.042241 0.323140 0.658789 7.744444 0.042241 0.327130 1.238459 7.838889 0.042241 0.331119 1.766110 7.933333 0.042241 0.335109 2.116678 8.027778 0.042241 0.339098 2.345642 8.122222 0.042241 0.343087 2.542783 8.216667 0.042241 0.347077 2.725495 8.311111 0.042241 0.351066 2.896554 8.405556 0.042241 0.355056 3.057945 8.500000 0.042241 0.359045 3.211146 8.594444 0.042241 0.363034 3.357293 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 *** Detention Facility 4/9/2026 1:09:26 AM Page 29 <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 Detention Facility 4/9/2026 1:09:26 AM Page 30 Predeveloped HSPF Message File Detention Facility 4/9/2026 1:09:26 AM Page 31 Mitigated HSPF Message File ERROR/WARNING ID: 238 1 The continuity error reported below is greater than 1 part in 1000 and is therefore considered high. Did you specify any "special actions"? If so, they could account for it. Relevant data are: DATE/TIME: 1999/ 9/30 24: 0 RCHRES : 1 RELERR STORS STOR MATIN MATDIF -4.505E-03 0.00000 0.0000E+00 0.00000 -4.600E-09 Where: RELERR is the relative error (ERROR/REFVAL). ERROR is (STOR-STORS) - MATDIF. REFVAL is the reference value (STORS+MATIN). STOR is the storage of material in the processing unit (land-segment or reach/reservior) at the end of the present interval. STORS is the storage of material in the pu at the start of the present printout reporting period. MATIN is the total inflow of material to the pu during the present printout reporting period. MATDIF is the net inflow (inflow-outflow) of material to the pu during the present printout reporting period. ERROR/WARNING ID: 238 1 The continuity error reported below is greater than 1 part in 1000 and is therefore considered high. Did you specify any "special actions"? If so, they could account for it. Relevant data are: DATE/TIME: 2002/ 8/31 24: 0 RCHRES : 1 RELERR STORS STOR MATIN MATDIF -6.852E-02 0.00000 0.0000E+00 0.00000 -2.688E-10 Where: RELERR is the relative error (ERROR/REFVAL). ERROR is (STOR-STORS) - MATDIF. REFVAL is the reference value (STORS+MATIN). STOR is the storage of material in the processing unit (land-segment or reach/reservior) at the end of the present interval. STORS is the storage of material in the pu at the start of the present printout reporting period. MATIN is the total inflow of material to the pu during the present printout reporting period. MATDIF is the net inflow (inflow-outflow) of material to the pu during the present printout reporting period. ERROR/WARNING ID: 238 1 The continuity error reported below is greater than 1 part in 1000 and is therefore considered high. Did you specify any "special actions"? If so, they could account for it. Relevant data are: Detention Facility 4/9/2026 1:09:26 AM Page 32 DATE/TIME: 2006/ 7/31 24: 0 RCHRES : 1 RELERR STORS STOR MATIN MATDIF -7.629E-02 0.00000 0.0000E+00 0.00000 -2.395E-10 Where: RELERR is the relative error (ERROR/REFVAL). ERROR is (STOR-STORS) - MATDIF. REFVAL is the reference value (STORS+MATIN). STOR is the storage of material in the processing unit (land-segment or reach/reservior) at the end of the present interval. STORS is the storage of material in the pu at the start of the present printout reporting period. MATIN is the total inflow of material to the pu during the present printout reporting period. MATDIF is the net inflow (inflow-outflow) of material to the pu during the present printout reporting period. Detention Facility 4/9/2026 1:09:26 AM Page 33 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. 2005-2026; 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