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HomeMy WebLinkAboutRS_Draft_Drainage_Review_TIR_20200421_v1 19-2612 Downtown Utility Improvement Project April 2020 City of Renton Drainage Review Technical Information Report Date: April 2020 Project: Renton Downtown Utility Improvement Project (DUIP) To: City of Renton From: Murraysmith 1. Project Overview 1.1 Project Description The City of Renton plans to upgrade existing water, sewer, and stormwater utility systems as part of the Downtown Utility Improvement Project (DUIP). Replacement, rehabilitation, and/or upsizing the individual utilities is planned based on age, capacity needs, condition, and/or maintenance requirements. Work is within the downtown area of Renton and is confined to the City right-of-way or utility easements. The project is in the City of Renton, WA, primarily on S 2nd Street and S 3rd Street, including several cross streets, as defined per the following and shown in the plans attached in Appendix A: • S 2nd St, between Rainier Ave S and the Cedar River • S 3rd St, between Hardie Ave SW and Burnett Ave S • Lake Ave S, between S 2nd St and S Tobin St • Shattuck Ave S, between S 2nd St and S 4th Pl • Whitworth Ave S, between S 2nd St and S 3rd St • Morris Ave S, between S 2nd St and S 3rd St • Smithers Ave S, between S 3rd St and S 4th St • Burnett Ave S at the intersection of S 2nd St • Mill Ave S, between Bronson Way S and S 3rd St • Sanitary sewer easements that connect to sewer mains in S 2nd St and S 3rd St 1.2 Design Standards The storm drainage improvements for this project will be designed in accordance with the City of Renton Municipal Code (4.6.030), and the 2017 City of Renton Surface Water Design Manual (SWDM). 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx 1.3 Drainage Basin and Threshold Discharge Areas Stormwater within the study area drains either to the Cedar River to the north or the Black River to the southwest. The general project area is approximately 185 acres in size, of which approximately 69 acres (37%) lie within the Cedar River Basin and approximately 116 acres (63%) lie within the Black River Basin. Within the project area, seven local drainage basins were identified and named according to their location: Logan, Williams, Wells, Main, Old City Hall, Lake and Shattuck. Five study area trunk lines outfall to the Cedar River to the northeast and two trunk lines discharge toward the Black River towards the south and west. The project is within a Level 1 and Level 2 Aquifer Protection Area as shown in Appendix B. Per the Renton SWDM, a Threshold Discharge Area (TDA) is defined as an onsite area that drains to a single natural discharge location, or multiple natural discharge locations that combine wi thin one-quarter mile downstream (as determined by the shortest flow path). TDAs are used for determining the applicability of Core Requirements for the project. A single TDA has been completed for stormwater analysis and can be found in Section 2 as Table 2. 2. Conditions and Requirements Summary 2.1 Applicability of Drainage Requirements The type of drainage review and applicability of the Core Requirements of the SWDM is dependent on the size and type of project. Table 1 below contains project-specific information for the TDA. The project will be constructed within the existing roadway. Restoration of the roadway after the utilities are installed will be in accordance with City of Renton standards, which require a trench patch and limited asphalt overlay. Sidewalks and curb ramps, where impacted, will be replaced in kind materials. The site area as it applies to the threshold discharge area is considered to be the total area of the overlay. Areas outside the overlay but within the right-of-way will not be affected or changed by this project. The existing project area, because it is asphalt or concrete, is all impervious, however, it is not considered ‘Replaced Impervious Surface’ because surfaces replaced for the sole purpose of installing utilities is excluded from this classification in the Renton SWDM (pg 1-7). The project area is considered “Land Disturbing Area” because the grind and overlay will result in a temporary change in the ground surface cover. Table 1 – Project Area Summary as Proposed Site Location Site Area 285,000 sf Existing Impervious Surface 285,000 sf Percent Existing Impervious Surface 100% 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx New Pollution Generating Impervious Surfaces 0 sf New Non-Pollution Generating Impervious Surfaces 0 sf Proposed Pervious 0 sf Replaced Impervious Surfaces 01 sf Land Disturbing Activity 285,0002 sf 1As defined in the 2017 City of Renton Surface Water Design Manual, “Replaced impervious surface means any existing impervious surface on the project site that is proposed to be removed and re-established is impervious surface, excluding impervious surface removed for the sole purposed of installing utilities” 2As defined in the 2017 City of Renton Surface Water Design Manual, “Land disturbing activity means any activity that results in a change in the existing soil cover.” Table 2 summarizes how certain project area characteristics determine the applicability of the project’s drainage requirements. The Full Drainage Review categories require demonstration of compliance with Core Requirements #1 through #9 and Special Requirements #1 through #6. The thresholds and applicability of requirement are addressed in the following sections. Table 2 – Determining Applicability of Core Requirements Threshold Discharge Area Is the Project a single-family residential project? No This project will upgrade existing water, sewer, and stormwater utilities. It is not a single-family project. Is the project a single-family residential project that results in greater than or equal to 2,000 sf of new plus replaced impervious surface or greater than or equal to 7,000 sf of land disturbing activity? No The project is not a single-family residential project. Does the new or redevelopment project result in greater than or equal to 2,000 sf of new plus replaced impervious surface or greater than or equal to 7,000 sf of land disturbing activity? Yes This project results in greater than 2,000 sf of new plus replaced impervious surface or greater than 7,000 sf of land disturbing activity. Does the project result in greater than 50 acres of new impervious surface within a sub-basin or multiple sub-basins that are hydraulically connected? No The project area is less than 50 acres. This results in a Full Drainage Review per Renton SWDM Section 1.1.2.4 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx 2.2 Core Requirements Per Table 1.1.2.2 of the Renton SWDM, the following Core Requirements apply for full drainage review. However, these requirements have exemptions or thresholds that may preclude or limit their application to the project TDA. The following text documents how each Core Requirement is addressed for the project TDA. • Core Requirement #1 -- Discharge at Natural Location • Core Requirement #2-- Offsite Analysis • Core Requirement #3 – Flow Control Facilities • Core Requirement #4 – Conveyance System • Core Requirement #5 – Erosion & Sediment Control • Core Requirement #6 – Maintenance & Operations • Core Requirement #7 – Financial Guarantees & Liability • Core Requirement #8 – Water Quality Facilities • Core Requirement #9 – On-Site BMP’s 2.2.1 Core Requirement #1 -- Discharge at Natural Location The drainage design will maintain existing drainage patterns and outflow locations (where runoff leaves the site) to existing piped conveyance systems. New structures will be placed as needed along the project site to connect to these systems. 2.2.2 Core Requirement #2 – Offsite Analysis The project is exempt from this requirement since the project does not change the rate, volume, duration, or location of discharges to and from the project site. The project will not adversely impact the downstream and/or upstream drainage system. See Chapter 1.2.2., Exemptions from Core Requirement #2 in the Renton SWDM. Five study area trunk lines outfall to the Cedar River to the northeast and two trunk lines discharge toward the Black River towards the south and west. 2.2.3 Core Requirement #3 – Flow Control Facilities As stated in the Renton SWDM, “Replaced impervious surface means any existing impervious surface on the project site that is proposed to be removed and re-established is impervious surface, excluding impervious surface removed for the sole purposed of installing utilities”. The project’s sole purpose is to install water, storm and wastewater utilities; therefore, no new impervious surfaces are added as a part of this project. The restoration will match existing site conditions, so net impervious surface area and runoff rates will not change. There will be no change to peak flow, duration, or volume of runoff as a result of this project. 2.2.4 Core Requirement #4 – Conveyance System This project is to replace existing stormwater infrastructure that is aging and, in some areas, does not meet the City’s minimum design standards. All new pipe has been designed to meet the 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx Renton SWDM conveyance system capacity standards as specified in section 1.2.4 as detailed in the Draft Conceptual Stormwater Design Report, see Appendix C. Design storm and modeling requirements for the existing and proposed conveyance systems met the following requirements: • Existing and new pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. • Pipe system structures may overtop for runoff events that exceed the 25 -year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a severe flooding problem or severe erosion problem. • Any overflow occurring onsite for runoff events up to and including the 100 -year event must discharge at the natural location for the project site. All modeling was conducted based on future build-out conditions allowed by current zoning regulations. 2.2.5 Core Requirement #5 – Erosion & Sediment Control A Stormwater Pollution Prevention Plan (SWPPP) and temporary erosion control plans will be prepared during the final design of the project. 2.2.6 Core Requirement #6 – Maintenance & Operations All proposed and existing stormwater system components will be maintained by the City in accordance with COR maintenance operations. Maintenance requirements for catch basins, manholes, and conveyance pipes are found in the Renton SWDM Appendix A Numbers 5 and 6. Therefore, a project specific Maintenance and Operations Manual is not required. 2.2.7 Core Requirement #7 – Financial Guarantees & Liability As a public project, financial guarantee and liability requirements are not applicable. 2.2.8 Core Requirement #8 – Water Quality Facilities The project is exempt from Core Requirement #8. The Surface Area Exemption and Surface Exemption for Transportation Redevelopment Projects detailed in Section 1.2.8 of the Renton SWDM state the project is exempt if the new impervious surface is less than 50% of the existing impervious surface, less than 5,000 square feet of new plus replaced pollution-generating impervious surface (PGIS) is created, and less than ¾ acre of new Pollution-generating pervious surface (PGPS) will be added. The replaced surface area included in this project does not qualify as an impervious surface per the Renton SWDM as detailed previously and the work is a precursor to a future transportation redevelopment project, therefore both exemptions apply. 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx 2.2.8 Core Requirement #9 – On-Site BMP’s The project is exempt from Core Requirement #9. The project’s sole purpose is to install water, storm and wastewater utilities; therefore, no new impervious surfaces are added as a part of this project. The restoration will match existing site conditions, so net impervious surface area and runoff rates will not change. There will be no change to peak flow, duration, or v olume of runoff as a result of this project. This project meets the requirements for Core Requirement #3 Flow Control Facilities; therefore, the Flow Control Facility Exemption applies. 2.3 Special Requirements The following are Special Requirements that may or may not be applicable to the project TDA. • Special Requirement #1 -- Other Adopted Requirements • Special Requirement #2 -- Flood Hazard Area Delineation • Special Requirement #3 -- Flood Protection Facilities • Special Requirement #4 -- Source Control • Special Requirement #5 -- Oil Control • Special Requirement #6 -- Aquifer Protection Area 2.3.1 Special Requirement #1 – Other Adopted Requirements There are no other applicable adopted requirements set forth by the City for the project area, therefore this project is exempt from Special Requirement #1. 2.3.2 Special Requirement #2 – Flood Hazard Area Delineation The project site is not within a Flood Hazard Area; therefore, this project is exempt from Special Requirement #2. 2.3.3 Special Requirement #3 -- Flood Protection Facilities There are no proposed flood protection facilities included with the proposed drainage system, therefore this project is exempt from Special Requirement #3. 2.3.4 Special Requirement #4 -- Source Control This project does not require a commercial building or commercial site development permit; therefore, the project is exempt from Special Requirement #4. 2.3.5 Special Requirement #5 -- Oil Control The traffic volumes within the project area meet the high-use site thresholds set forth by Special Requirement #5 in the Renton SWDM. According to the 2016 WSDOT Annual Traffic Report, Rainier Ave is the only street within the project area with an average daily traffic (ADT) exceeding 18-2251 Downtown Utility Improvement Project April 2020 City of Renton H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\Phase 3 - Final Design\401-Environmental and Permitting\Drainage Review TIR\Draft Drainage Review Technical Information Report.docx 25,000 cars. There are no planned stormwater improvements in the vicinity of Rainier Ave, therefore, oil control has not been included in this project. 2.3.6 Special Requirement #6 -- Aquifer Protection Area A portion of the project area lies within Zone 1 of an Aquifer Protection area, and the remainder is within Zone 2 as shown in Appendix B. The proposed drainage improvements meet the requirements set forth by Special Requirement #6 of the Renton SWDM. The project does not include any open facilities or open conveyance system. 19-2612 Downtown Utility Improvement Project April 2020 City of Renton APPENDIX A: PROJECT AREA H:\EVT_Projects\18\2251 - Renton DUIP Phase 2\CAD\GIS\18-2251-WA-PROJECT LIMITS.mxd 10/18/2019 1:08:48 PM kent.harjalaC i t y o f R e n t o n D U I PWater, S e w e r , a n dStormwater I m p r o v e m e n t s Pr ojectImprovemen ts© EXISTING UTILITY SYSTEMS & BASE DATA: CITY OF RENTON 2017, UNLESS OTHERWISE NOTED. KING COUNTY INTERCEPTOR DATA: KING COUNTY 2017. DATA SOURCE SUPPLIED MAY NOT REFLECT CURRENT OR ACTUAL CONDITIONS. THIS MAP IS A GEOGRAPHIC REPRESENTATION BASED ON INFORMATION AVAILABLE. IT DOES NOT REPRESENT SURVEY DATA.NO WARRANTY IS MADE CONCERNING THE ACCURACY, CURRENCY, OR COMPLETENESS OF DATA DEPICTED ON THIS MAP. 0 300150 Scale in Feet???????????????????????????????"" 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KING COUNTY INTERCEPTOR DATA: KING COUNTY 2017. DATA SOURCE SUPPLIED MAY NOT REFLECT CURRENT OR ACTUAL CONDITIONS. THIS MAP IS A GEOGRAPHIC REPRESENTATION BASED ON INFORMATION AVAILABLE. IT DOES NOT REPRESENT SURVEY DATA.NO WARRANTY IS MADE CONCERNING THE ACCURACY, CURRENCY, OR COMPLETENESS OF DATA DEPICTED ON THIS MAP. 0 300150 Scale in Feet???????????????????????????????"" 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Talich, P.E. Project Manager Rebecca Loveday Ochiltree, P.E. Project Engineer 37426STATE O F WASHIN G T ONR EGI S T E R EDPROF E SSIONA L E N G INEERACRLCA L I T H.GA 45243STATEOFWASHIN G T ONR EGI S T E R EDP R OFESSIONA L E N G IN EER REBL DAY O C HI LTREEECCAO V E City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report i TABLE OF CONTENTS 1. Introduction .......................................................................................................................................... 1 1.1 Background ................................................................................................................................... 1 1.2 Project Improvements and Phasing ............................................................................................... 1 1.3 Study Area and Scope of Work ...................................................................................................... 1 1.4 Potential Impacts on Other Utilities ................................................................................................ 2 2. Applicable Standards and Design Criteria ........................................................................................... 2 2.1 General .......................................................................................................................................... 2 2.2 Stormwater Hydrology ................................................................................................................... 2 2.3 System Hydraulics ......................................................................................................................... 3 3. Study Area ........................................................................................................................................... 3 3.1 Previous Studies and Sources of Information ................................................................................ 3 3.2 Basin Delineation ........................................................................................................................... 4 3.3 Land Use Conditions ..................................................................................................................... 6 3.3.1 Zoning .................................................................................................................................... 6 3.3.2 Percent Impervious and Pervious Areas ................................................................................ 8 4. Model Overview ................................................................................................................................. 10 4.1 General ........................................................................................................................................ 10 4.2 Hydrologic Model Inputs .............................................................................................................. 10 4.2.1 Precipitation Data ................................................................................................................ 10 4.2.2 Runoff Curve Number (RCN) ............................................................................................... 10 4.2.3 Time of Concentration (Tc) .................................................................................................. 11 4.3 Hydraulic Model Inputs ................................................................................................................ 12 4.3.1 Conveyance System Geometry ........................................................................................... 12 4.3.2 Hydrologic Input Locations .................................................................................................. 13 4.3.3 Pipe Roughness .................................................................................................................. 13 4.3.4 Downstream Boundary Conditions ...................................................................................... 13 4.3.5 Junction Loss Coefficients ................................................................................................... 16 4.3.6 Gutter Flow (Overflow Links) ............................................................................................... 17 4.3.7 Sensitivity Analysis .............................................................................................................. 17 5. Model Results .................................................................................................................................... 18 5.1 Existing Conveyance System ...................................................................................................... 18 5.1.1 Existing Conveyance System Deficiencies .......................................................................... 19 5.1.2 Select Model Results ........................................................................................................... 19 5.1.3 Problem Area Prioritization .................................................................................................. 20 5.2 Alternatives Analysis .................................................................................................................... 20 5.2.1 General ................................................................................................................................ 20 5.2.2 Alternative 1 ......................................................................................................................... 21 5.2.3 Alternative 2 ......................................................................................................................... 22 5.2.4 Alternative 3 ......................................................................................................................... 22 5.3 Preferred Alternative .................................................................................................................... 23 6. Regulatory Considerations for Future Phases ................................................................................... 25 6.1 General Requirements ................................................................................................................. 25 6.2 Drainage Requirements ............................................................................................................... 26 6.2.1 Drainage Review Types and Requirements ......................................................................... 26 City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report ii 6.2.2 Direct Discharge Exemption ................................................................................................ 28 6.2.3 Modeling Requirements ....................................................................................................... 28 6.2.4 Outfall Improvements to Cedar River: .................................................................................. 30 7. References ........................................................................................................................................ 32 LIST OF TABLES Table 1 Study Area Basin Summary ............................................................................................................. 5 Table 2 Study Area Zoning ........................................................................................................................... 6 Table 3 Sub-basin Zoning Areas (Acres) ...................................................................................................... 7 Table 4 Effective Impervious Area based on Zoning .................................................................................... 8 Table 5 Sub-basin Breakdown of Pervious and Impervious Area ................................................................. 9 Table 6 Precipitation Summary ................................................................................................................... 10 Table 7 Runoff Curve Numbers .................................................................................................................. 11 Table 8 Time of Concentration Coefficients ................................................................................................ 11 Table 9 Time of Concentration Summary ................................................................................................... 12 Table 10 Manning’s Roughness Coefficients .............................................................................................. 13 Table 11 Cedar River– Outfall Boundary Conditions .................................................................................. 14 Table 12 Prior Modeling Results for 25-year Storm .................................................................................... 15 Table 13 Black River– Outfall Boundary Conditions ................................................................................... 16 Table 14 Loss Coefficients – Existing Stormwater System ......................................................................... 17 Table 15 Material Quantities - Alternative 1 ................................................................................................ 21 Table 16 Material Quantities - Alternative 2 ................................................................................................ 22 Table 17 Material Quantities - Alternative 3 ................................................................................................ 23 Table 18 Materials Quantity Summary ........................................................................................................ 25 Table 19 Drainage Review Core Requirements.......................................................................................... 27 LIST OF FIGURES Figure 1 – Stormwater Study Area Figure 2 – Basin Delineation Figure 3 – Sub-basin Delineation Figure 4 – Zoning Figure 5 – Model Schematic Figure 6 – Existing System Deficiencies (Fixed Backwater Elevation: 23.3 feet) Figure 6A – Existing System Deficiencies (Fixed Backwater Elevation: 19.5 feet) Figure 7 – Alternative 1 Proposed Improvements Figure 8 – Alternative 2 Proposed Improvements Figure 9 – Alternative 3 Proposed Improvements Figure 10 – Preferred Alternative LIST OF APPENDICES Appendix A – Model Input Appendix B – Select Model Results City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 1 1. Introduction 1.1 Background The City of Renton (City) is planning to redevelop and revitalize its downtown city center. The City recently prepared a City Center Community Plan that includes goals such as creating a dynamic civic node in downtown, encouraging private redevelopment, improving access both locally and regionally, and protecting and enhancing downtown residential neighborhoods. The City has decided to convert S 2nd and S 3rd Streets, which are one-way streets, to two-way streets in the interest of decreasing pass-thru traffic from I-405 and creating an improved and safer pedestrian environment. The downtown area is known to have old insufficient infrastructure that may need to be upgraded or replaced to accommodate redevelopment. This project is intended to evaluate the existing stormwater conveyance system within downtown Renton, identify and prioritize deficiencies, and make recommendations to address stormwater conveyance for the future developed condition. The evaluation focuses on trunk conveyance and excludes roadway drainage (collection facilities), flow control, and water quality treatment facility analyses. 1.2 Project Improvements and Phasing This report was prepared under Phase I – Conceptual Analysis and Design, and evaluates the capacity of the existing storm water conveyance system within the downtown area. Other aspects of Phase I include evaluations of sewer and water system infrastructure, which are presented under separate reports. General plans for improvement within the downtown area include:  Upgrades to utilities to encourage private redevelopment projects  Desire for festival type curbs at Burnett and 2nd Street  Transportation improvements in the area of Wells and Williams between 2nd and 3rd Streets  Plans to move the transit center closer to Grady Way and Rainier Avenue S and use the existing parking garage for downtown parking 1.3 Study Area and Scope of Work The approximate limits of the study area for storm water have been defined with Rainier Avenue South as the western boundary, Airport Way as the northern boundary, and Houser Way S as the eastern and southern boundaries. The study area limits are shown on Figure 1. Approximately one third of the study area is located within the Lower Cedar River Drainage Basin and the remaining two thirds is located within the Black River Drainage Basin. Five study area trunk lines outfall to the Cedar River to the northeast and two trunk lines discharge towards the Black River towards the south and west. Stormwater analyses included evaluating both the existing conveyance system and proposed improvements. The existing system evaluation included data review, field reconnaissance, regulatory and design criteria definition, evaluation of land use and zoning characteristics, hydrologic and hydraulic analyses of the existing conveyance system, and identification of conveyance system deficiencies. The proposed system evaluation included developing alternatives to correct stormwater conveyance deficiencies, alternatives analysis hydraulic modeling, and working with the City to select the preferred alternative to carry forward into the design phase. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 2 1.4 Potential Impacts on Other Utilities Many different utilities lie within the study area. There are several large diameter transmission mains and sewer interceptors that will need to be avoided for this project. Smaller systems, including water distribution and sewer collection piping within the study area are being evaluated as part of the Downtown Utility Improvements project under a separate report. The Seattle Public Utilities (SPU) water line corridor runs through the study area, with right-of-way (ROW) easements primarily located between S 2nd and 3rd Streets. The SPU pipe alignments are shown in blue on Figure 1. Three large diameter SPU Cedar River supply pipelines (CRPLs) run through the SPU ROW easement corridor. SPU does not allow waterlines to cross beneath CRPLs due to potential for pressure lines to break and jeopardize CRPL integrity. Storm drain pipeline crossings may be acceptable, since they are not pressurized. SPU requires review and approvals of storm line construction, operation, and maintenance within their ROW. The City’s preference is to avoid installing new stormwater systems in the SPU ROW. For existing storm drain within the SPU ROW, such as between Shattuck Ave S and Logan Ave S, the City would like to consider providing alternate stormwater collection and conveyance outside of the SPU ROW. The King County Sewer Interceptor runs in a north-south alignment beneath Burnett Ave. This pipeline, shown in green on Figure 1, is known to be deep and is not anticipated to affect proposed stormwater improvements. 2. Applicable Standards and Design Criteria 2.1 General The December 2016 City of Renton (COR) Surface Water Design Manual (SWDM) was referenced for determining the design storm and modeling requirements for the existing and proposed conveyance system. For criteria not available in the COR SWDM, the April 2016 King County Surface Water Design Manual and the Washington State Department of Ecology Stormwater Management Manual for Western Washington (Amended December 2014) were referenced. Other reference documents include:  City of Renton Comprehensive Plan (June 2015)  City of Renton City Center Community Plan (2017)  King County Surface Water Design Manual (January 1990, Revised November 1995)  Washington State Department of Ecology Stormwater Management Manual for Western Washington (August 2001)  US Department of Transportation Federal Highway Administration, Hydraulic Engineering Circular No. 22, Urban Drainage Design Manual (September 2009, Revised August 2013) 2.2 Stormwater Hydrology In accordance with COR SWDM Table 3.2: Acceptable Uses of Runoff Computation Methods, the Santa Barbara Unit Hydrograph (SBUH) method is acceptable for peak flow conveyance sizing for tributary areas greater or equal to 10 acres and where no storage routing is performed; and SBUH is acceptable for use in downstream analysis for projects in Full or Targeted Drainage Review where tributary areas are greater or City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 3 equal to 10 acres if no storage routing is performed. SBUH was selected for conveyance capacity hydrologic modeling. For this project, modeling conducted to evaluate the existing stormwater system was based on future build- out conditions allowed by current zoning designations. The land use for both existing and proposed conditions is based on the COR Comprehensive Plan Zoning Land Use map, effective July 1, 2015. One exception was made to this criteria for the Renton High School property. Pervious areas, including ball fields and landscaping, were assumed to remain pervious. 2.3 System Hydraulics Conveyance Design Requirements are described in COR SWDM Section 1.2.4.1 under Core Requirement #4. Design storm and modeling requirements for the existing and proposed conveyance systems include:  Existing and new pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas.  Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a severe flooding problem or severe erosion problem.  Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. 3. Study Area The stormwater study area, shown on Figure 1, was selected to extend approximately one to two blocks north and south of the core downtown area and cover the area between Rainier Avenue S and I-405. 3.1 Previous Studies and Sources of Information Several prior stormwater analyses have been prepared for areas downstream of the study area and provide useful information. No reports or prior models have been developed specific to the downtown area. The following reports and data were referenced:  Renton Stormwater Network GIS Data  Cedar River 205 Levee System Interior Drainage Analysis (Tetra Tech 2017)  Draft Hardie Avenue SW – SW 7th Street Storm System Improvement Project, Supplemental Hydrologic and Hydraulic Analysis Report (Louis Berger 2016)  Draft SW 7th Street Storm Drainage Alternatives Analysis and Preliminary Design Memorandum, City of Renton, and associated XPSWMM model (SAIC 2012)  Rainier Avenue South Improvement Project – SW Grady Way to S 2nd Street, Surface Water Technical Information Report (GHD 2011)  Hydrologic and Hydraulic Report, Lake Avenue South Storm System Project (H&H Report) (Parametrix 2011)  City of Renton, Shattuck Avenue Stormwater Diversion Modeling Report (GHD 2010)  Rainier Ave (SR 167) Improvements Project Phase 1 Shattuck Ave S Stormwater Bypass System Record Drawings (DMJM Harris|AECOM 2010)  Cedar River FEMA Flood Insurance Study and Rate Maps (FEMA 2010)  Cedar River HEC-RAS Sediment Model (City of Renton 2008) City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 4 3.2 Basin Delineation Stormwater within the study area drains either to the Cedar River to the north or the Black River to the southwest, as shown on Figure 1. The study area is approximately 185 acres in size, of which approximately 69 acres (37%) lie within the Cedar River Basin and approximately 116 acres (63%) lie within the Black River Basin. Within the study area, seven drainage basins were identified and named according to their location. The seven drainage basins are Logan, Williams, Wells, Main, Old City Hall, Lake, and Shattuck. The study area basin delineation is shown on Figure 2. Basins were divided into sub-basins for hydrologic and hydraulic modeling purposes. Sub-basins are smaller, isolated catchments located within a drainage basin and are useful for inputting smaller components of overall flows at different locations through a trunk conveyance system in the model. For example, the Lake basin was subdivided into eight sub-basins, Lake-1 through Lake-8. Select sub-basins were further divided during modeling, for example, Lake-1 was divided into two parts, labeled Lake-1a and Lake-1b. Sub-basin delineation is presented on Figure 3. Chart 1 and Table 1 provide a summary of the breakdown of sub-basins within the approximately 185-acre study area. Five outfalls to the Cedar River are included in this evaluation and occur at Logan Ave S, Williams Ave S, Wells Ave S, Main Ave S, and near the former City Hall property between Bronson Way N and Houser Way S. Two drainage basins outlet towards the Black River, with one discharging towards Rainier Ave S and Sunset Blvd and the other along Shattuck Avenue S, leaving the study area at S 4th Place. The locations where stormwater discharges from the study area are labeled as Outfall Conveyance Boundaries and are shown on Figures 1, 2, and 3. Logan-1 Logan-2 Logan-3 Williams-1 Williams-2 Williams-3 Wells Main Old City Hall-1 Old City Hall-2 Lake-1 Lake-2Lake-3Lake-4 Lake-5 Lake-6 Lake-7 Lake-8 Shattuck-1 Shattuck-2 Shattuck-3 Shattuck-4 Shattuck-5 Chart 1. Study Area Sub-basins City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 5 Table 1 Study Area Basin SummaryStudy Area Receiving Water Basin Outfall Location Sub-basin Area (Ac) Sub-basin (divided) Area (Ac) Total Area 184.47 acres Black River 115.75 acres Lake 80.47 acres Rainier Ave S and SW Sunset Blvd Lake-1 11.79 Lake-1a Lake-1b9.14 2.65Lake-2 3.37Lake-3 10.70Lake-4 10.55 Lake-4a Lake-4b7.68 2.87Lake-5 4.99Lake-6 11.01 Lake-6a Lake-6b 8.45 2.56 Lake-7 15.81Lake-8 12.25 Lake-8a Lake-8b 7.09 5.16 Shattuck 35.28 acres Shattuck Ave S and S 4th Pl Shattuck-1 4.25Shattuck-2 5.25Shattuck-3 11.91 Shattuck-3a Shattuck-3b 3.97 7.94 Shattuck-4 6.80Shattuck-5 7.07Cedar River 68.72 acres Logan 35.68 acres Logan Ave S and Cedar River Logan-1 5.55Logan-2 15.88 Logan-2a Logan-2b Logan-2c 5.56 7.06 3.26 Logan-3 14.25 Logan-3a Logan-3b Logan-3c Logan-3d5.59 2.65 3.35 2.66Williams 15.61 acres Williams Ave S and Cedar River Williams-1 1.99 Williams -2 7.82 Williams-3 5.80 Wells 5.66 acres Wells Ave S and Cedar River Wells 5.66 Main 3.69 acresMain Ave S and Cedar RiverMain 3.69 Old City Hall 8.08 acres Bronson Way S/Mill Ave S and Cedar River Old City Hall-1 3.41 Old City Hall-2 4.67 City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 6 3.3 Land Use Conditions 3.3.1 Zoning Hydrologic Analysis for the existing conveyance system is based on the Land Use Zoning map dated July 1, 2015 presented in the 2015 COR Comprehensive Plan. One land use condition was selected for the study, based on presently allowed zoning, because the study area is already developed and hydrologic parameters for the existing condition are anticipated to be similar to those based on allowed zoning. Study area Zoning is shown on Figure 4. Zoning within the study area includes residential, commercial, center-downtown, and industrial zoning. Nearly half (47%) of the study area is zoned as center-downtown (CD), 20% is zoned as commercial arterial (CA), 7% is zoned for residential, and 1% is zoned as industrial. The remaining 25% is ROW. Table 2 and Chart 2 present the zoning composition within the study area. Table 2 Study Area Zoning Zoning Area (Ac) Percent R-8 Residential, 8 dwelling units per acre 6.05 3% R-14 Residential, 14 dwelling units per acre 6.68 4% CA Commercial Arterial 37.44 20% CD Center Downtown 89.16 47% IM Industrial - Medium 1.45 1% ROW Right-of-Way 45.68 25% Total 184.47 100% 3%4% 20% 47% 1% 25% Chart 2. Zoning R8-Residential 8 du/ac R14-Residential 14 du/ac CA-Commercial Arterial CD-Center Downtown IM-Industrial - Medium ROW-Right-of-Way City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 7 Table 3 Sub-basin Zoning Areas (Acres) Sub-basin ID R-8 Residential R-14 Residential CA Commercial Arterial CD Center Downtown IM Industrial Medium Right- of-Way Total Area Lake-1a 7.32 1.82 9.14 Lake-1b 2.32 0.33 2.65 Lake-2 2.08 0.56 0.74 3.37 Lake-3 2.15 7.82 0.72 10.70 Lake-4a 5.88 1.81 7.68 Lake-4b 0.25 0.82 1.80 2.87 Lake-5 3.74 1.26 4.99 Lake-6a 8.45 0.00 8.45 Lake-6b 1.50 1.06 2.56 Lake-7 15.09 0.72 15.81 Lake-8a 5.27 1.82 7.09 Lake-8b 3.84 1.32 5.16 Shattuck-1 0.18 1.63 2.43 4.25 Shattuck-2 2.67 1.39 1.19 5.25 Shattuck-3a 1.28 1.31 1.38 3.97 Shattuck-3b 2.55 2.63 2.76 7.94 Shattuck-4 1.86 3.55 1.40 6.80 Shattuck-5 2.85 1.21 1.24 1.77 7.07 Logan-1 1.66 0.20 1.45 2.23 5.55 Logan-2a 1.40 2.77 1.39 5.56 Logan-2b 5.08 1.99 7.06 Logan-2c 2.51 0.75 3.26 Logan-3a 3.43 2.15 5.59 Logan-3b 1.63 1.02 2.65 Logan-3c 2.06 1.29 3.35 Logan-3d 1.63 1.02 2.66 Williams-1 1.77 0.22 1.99 Williams-2 5.87 1.94 7.82 Williams-3 3.99 1.81 5.80 Wells 4.13 1.53 5.66 Main 2.44 1.26 3.69 Old City Hall-1 2.25 1.16 3.41 Old City Hall-2 3.08 1.59 4.67 Total Areas 6.05 6.68 37.44 87.16 1.45 45.68 184.47 City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 8 3.3.2 Percent Impervious and Pervious Areas COR SWDM Table 3.2.2.C lists percent impervious coverage for use in runoff modeling analysis of existing residential areas. The net hydrologic response of an impervious area depends on whether that area is effectively connected (usually by pipes or a channel) to a storm drainage system. The impervious area that the user inputs to the hydrologic model is the Effective Impervious Area (EIA). For commercial land use, King County SWDM Table 3.2.2.D: Effective Impervious Fraction, provides values of 0.95 and 1.00 for predevelopment and post-development, respectively. These values were deemed overly conservative for this study and were further evaluated. A prior study conducted for the downtown study area (Parametrix 2011) assigned EIA for zoning codes CA and CD to 90 and 95 percent EIA, respectively. The City’s current development standards, including setbacks and landscaping requirements may also result in lower impervious area on a redeveloped site. A 2014 Technical Information Report for a retail development within CA zoning was referenced. The predeveloped 3-acre site was 98% impervious. The proposed redeveloped site, after implementing setback and landscaping requirements, is 82% impervious. Based on the two examples described, EIA for CA was set at 85% and EIA for CD, IM, and ROW was set to 90%. Renton High School grassed athletic fields and landscaped areas fall within CA and CD zoning; however, they will be modeled as grass. It is assumed that the grassed fields will remain in the future condition and/or future flows from these areas will be required to mimic those generated by the existing pervious area. The grassed fields are located in sub-basins Lake-3 and Lake-7. Impervious areas within these sub- basins were measured. Effective Impervious Area (EIA) for study area zoning codes are summarized in Table 4. Table 4 Effective Impervious Area based on Zoning Zoning Effective Impervious Area (%) Residential-8 (R-8)1 75 Residential-14 (R-14)1 85 Commercial Arterial (CA) 85 Commercial Downtown (CD) and Industrial - Medium (IM) 90 Renton High School 2 Site-specific, to be measured Right-of-Way 90 Notes: 1 COR SWDM 2017 Table 3.2.2.C: Maximum Impervious Coverage for Residential Areas. Remaining pervious areas are assumed to be grass in good condition. 2 Grass fields to be modeled as grass for the future condition. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 9 Table 5 presents impervious and pervious areas calculated for each sub-basin based on the EIA for each zoning category. Table 5 Sub-basin Breakdown of Pervious and Impervious Area Sub-basin ID Area (Ac) Percent Impervious Impervious Pervious Total Lake-1a 7.86 1.28 9.14 86% Lake-1b 2.03 0.61 2.65 77% Lake-2 2.72 0.65 3.37 81% Lake-3 1.44 9.26 10.70 13% Lake-4a 6.62 1.06 7.68 86% Lake-4b 2.51 0.37 2.87 87% Lake-5 4.31 0.69 4.99 86% Lake-6a 7.19 1.27 8.45 85% Lake-6b 2.23 0.33 2.56 87% Lake-7 13.75 2.06 15.81 87% Lake-8a 6.38 0.71 7.09 90% Lake-8b 4.64 0.52 5.16 90% Shattuck-1 3.82 0.43 4.25 90% Shattuck-2 4.59 0.66 5.25 87% Shattuck-3a 3.49 0.48 3.97 88% Shattuck-3b 6.99 0.95 7.94 88% Shattuck-4 6.03 0.77 6.80 89% Shattuck-5 6.16 0.91 7.07 87% Logan-1 4.91 0.64 5.55 89% Logan-2a 4.79 0.77 5.56 86% Logan-2b 6.36 0.71 7.06 90% Logan-2c 2.94 0.33 3.26 90% Logan-3a 5.03 0.56 5.59 90% Logan-3b 2.39 0.27 2.65 90% Logan-3c 3.02 0.34 3.35 90% Logan-3d 2.39 0.27 2.66 90% Williams-1 1.79 0.20 1.99 90% Williams-2 7.03 0.78 7.82 90% Williams-3 5.22 0.58 5.80 90% Wells 5.10 0.57 5.66 90% Main 3.32 0.37 3.69 90% Old City Hall-1 3.07 0.34 3.41 90% Old City Hall-2 4.20 0.47 4.67 90% Total 154.34 30.12 184.47 84% Note: 1) Measured grass area at Renton High School (sub-basins Lake-3 and Lake-7) City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 10 4. Model Overview 4.1 General Hydrologic and hydraulic modeling is needed for the existing conditions within the study area to evaluate the capacity of the existing storm drainage network and define design flow rates for future improvements. Existing conditions model results serve as the basis for developing, analyzing, and comparing alternatives that will provide conveyance of storm flows within the City’s design criteria. 4.2 Hydrologic Model Inputs Hydrologic calculations for the conveyance system evaluation includes estimating peak flows for the 10-, 25-, and 100-year 24-hour storms using the SBUH method. This runoff computation method is acceptable per Table 3.2 of the COR SWDM. For the SBUH methodology, the following inputs are needed for each drainage sub-basin:  Precipitation Data  Runoff Curve Number (RCN)  Time of Concentration (Tc)  Percent Impervious Area Inputs including precipitation data, RCN, and Tc are described in the following subsections (4.2.1 through 4.2.3), while percent impervious areas are provided in Section 3.3.2. 4.2.1 Precipitation Data Precipitation values for the 2-, 10-, 25-, and 100-year storm events are referenced from COR SWDM Figure 3.2.1 and presented in Table 6. Table 6 Precipitation Summary Frequency 24-hour Precipitation (inches) 2-year 2.0 10-year 2.9 25-year 3.4 100-year 3.9 4.2.2 Runoff Curve Number (RCN) Runoff Curve Number (RCN) is generally based on soil type and land cover. Approximately 95% of the soils within the study area are mapped as Urban Land and the remaining 5% are mapped as Beausite (BeC and BeD) (USDA NRCS 2016). According to COR SWDM Table 3.2.2.A, Beausite soil type is a glacial till soil, classified as hydrologic soil group (HSG) C. Soils within the study area are assumed to be HSG C. Geotechnical data review completed by Kleinfelder under contract to Murraysmith for this project, confirmed that HSG C is appropriate for the study area. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 11 RCNs for the study area are referenced from COR SWDM Table 6.4.1.1.A, Runoff Curve Numbers for Selected Agricultural, Suburban, and Urban Areas. Table 7 Runoff Curve Numbers Cover Type and Hydrologic Condition Runoff Curve Number Impervious Paved parking lots, roofs, driveways 98 Pervious Open Space (lawns, parks, golf courses, cemeteries, landscaping) 86 Pasture, grassland in fair condition (ground cover 50% to 75%) 79 Pasture, grassland in good condition (ground cover greater than 75%) 74 Impervious areas will be modeled using RCN equal to 98. As shown on Table 5, approximately 84% of the study will be modeled as impervious. Three values for pervious area RCN, shown in Table 7, were considered for the study area. An existing conditions hydraulic model sensitivity analysis was conducted, as described in Section 4.3.7, and concluded that RCN of 86 appears to overpredict runoff; therefore, the pervious area RCN of 79 was selected for modeling both existing conditions and proposed alternatives. 4.2.3 Time of Concentration (Tc) Time of Concentration (Tc) calculations were completed using the methodology outlined in the King County Surface Water Design Manual (KCSWDM 1990). The same procedure and coefficients are also presented in the Washington State Department of Ecology Stormwater Management Manual for Western Washington (Ecology 2001). Coefficients used for calculating Tc are presented in Table 8. Table 8 Time of Concentration Coefficients Sheet Flow Manning’s Roughness Coefficient, ns (for the initial 300 feet of travel) Surface ns Smooth surfaces (concrete, asphalt, gravel, packed bare soil) 0.011 Short prairie grass and lawns 0.15 Velocity Factor, ks (shallow concentrated) and kc (channel) flow Shallow Concentrated Flow ks Short grass, pasture, lawn (n=0.030) 11 Paved and gravel areas (n=0.012) 27 Channel flow (intermittent, beginning of visible channels) kc Grassed waterway (n = 0.030) 17 Concrete pipe 42 A velocity factor, kc, of 42 for concrete pipe was selected from Table 3.5.2C (KCSWDM 1990) and was used for Tc calculations within the study area. Velocity factor, kc, can also be calculated based on pipe diameter and Manning’s roughness coefficient. Calculated kc for a range of pipe types (plastic, ductile iron, concrete, and clay) and diameters (8-inch to 48-inch) is presented in Appendix A. The majority of the pipe within the system, especially near the hydrologic input locations described in Section 4.3, is 8- to 12-inch concrete pipe. The calculated values for kc range from 34.7 to 49.3. The selected value of 42 lies within City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 12 the range of calculated values and was therefore determined appropriate for use within the overall study area. A sample Tc calculation was performed to determine how much the estimated Tc would differ based on the calculated kc. The result was that the Tc value changed by less than one minute; therefore, the table value of 42 was determined appropriate for all sub-basins. Tc for rainfall on each sub-basin to reach the point of concentration – pipe or channel inlet, or catch basin is summarized in Table 9. Table 9 Time of Concentration Summary Sub-basin Tc (minutes) Sub-basin Tc (minutes) Lake-1a 31 Logan-1 6 Lake-1b 31 Logan-2a 31 Lake-2 17 Logan-2b 31 Lake-3 65 Logan-2c 12 Lake-4a 21 Logan-3a 16 Lake-4b 17 Logan-3b 6 Lake-5 11 Logan-3c 6 Lake-6a 20 Logan-3d 6 Lake-6b 6 Williams-1 6 Lake-7 32 Williams-2 6 Lake-8a 20 Williams-3 6 Lake-8b 21 Wells 6 Shattuck-1 30 Main 6 Shattuck-2 6 Old City Hall-1 31 Shattuck-3a 19 Old City Hall-2 6 Shattuck-3b 18 Shattuck-4 17 Shattuck-5 15 4.3 Hydraulic Model Inputs Hydrologic and hydraulic modeling was conducted using XPSWMM Version 2014 Service Pack 1 (XP Solutions 2015). XPSWMM was selected because the City is most familiar with its use and other Renton stormwater evaluations have been performed using this model. Version 2014 Service Pack 1 was selected to be consistent with the City’s current version of the software. 4.3.1 Conveyance System Geometry Model geometry, presented on Figure 5, has been set up using geospatial referencing and is based on the City’s GIS system inventory. Several data sources were reviewed to determine existing conveyance elements and confirm flow routes. Stormwater system information was downloaded from the City’s GIS database, reviewed, and compared to available City record drawings. Several historic drainage reports, hydrologic and hydraulic models, and design reports provided by the City were reviewed. Data gaps and inconsistencies were reconciled through review of record drawings, drainage studies, site visits, and limited City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 13 field survey. Where record drawings and survey data were used to fill gaps in the GIS data, a note was made in the XPSWMM file describing the change. Within the model, existing manholes, catch basins, conveyances are labeled with an “E” for existing. Proposed elements, included in the alternatives analysis, are labeled with a “P” for proposed. Nodes (catch basins, manholes, and structures) within the model network are labeled according to the City’s asset number. Links (pipes and ditches) are referenced to the upstream structure name. An example of a pipe name is, “E_US Node_.1”. Some areas, covered by older record drawings, appeared to be referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29) instead of the North Atlantic Vertical Datum of 1988 (NAVD 88). Within the study area, the difference between these two datums is 3.56 feet. Where pipe segments appeared to be different by this amount along a particular pipe run, the inverts were adjusted by 3.56 feet and a note was inserted into the XPSWMM file. 4.3.2 Hydrologic Input Locations Nodes shown in blue in Figure 5 represent hydrologic input locations for each sub-basin. This is the point where sub-basin runoff generated using SBUH enters the hydraulic network. 4.3.3 Pipe Roughness Pipe materials for the existing conveyance system were referenced from GIS and record drawing information. Manning’s roughness coefficients for conveyance pipes are referenced from COR SWDM Table 4.2.1.D and the Civil Engineering Reference Manual (Lindeburg 2005) and are presented in Table 10. Table 10 Manning’s Roughness Coefficients Pipe Material Manning’s Roughness Coefficient (n) Clay 0.013 Concrete (reinforced concrete pipe) 0.013 Concrete (cast-in-place) 0.015 Corrugated metal pipe 0.024 Ductile iron 0.012 Plastic (PVC, HDPE, and CPE) 0.012 4.3.4 Downstream Boundary Conditions Downstream boundary conditions occur at seven locations and include five locations along the Cedar River, one near Rainier Ave S and SW Sunset Blvd, and one near Shattuck Ave S and S 4th Place. Boundary conditions at these locations include assumptions for water surface elevation (or tailwater elevation) and are based on available information and engineering judgement. Monitoring data, such as records for water levels within existing manhole structures, is not presently available. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 14 Cedar River Outfalls The bed of the Cedar River through the channelized downtown Renton area is known to aggrade over time and is periodically dredged, as recommended in the US Army Corps of Engineers report “Cedar River at Renton Flood Damage Reduction Operation and Maintenance Manual: Cedar River Section 205 (Renton, Washington)” (USACE 2004). The most recent dredge cycle spanned from 1999 to 2016. Several HEC- RAS models have been prepared for the Cedar River with varying bed levels that correlate to various years within the dredge cycle. The 2008 Cedar River HEC-RAS Sediment Model provided by the City was selected because it is in the middle of the 1996-2016 dredging cycle and provides an average bed level for the river. Model plan, “Cedar2008”, includes 2008 geometry that represents a real bathymetric survey of the river bed from that year. HEC-RAS model cross sections that occur on or near stormwater outfall locations simulated in the XPSWMM model are shown in Table 11. Based on the Interior Drainage Analysis (TetraTech 2017), high flows in the Cedar River lag storm flows in downtown Renton. During a 10-, 25-, and 100-year rainfall event in downtown Renton, it is assumed that the water level in the Cedar River will correlate to the 2-, 10-, and 25-year water levels identified in the HEC-RAS model, respectively. Fixed backwater elevations at each boundary condition location are presented in Table 11. Table 11 Cedar River– Outfall Boundary Conditions Basin Location (XPSWMM Node) HEC-RAS Cross Section and Location Fixed Backwater Elevation at Outfall (feet) Tide gate? (yes/no) 10-year storm 25-year storm 100-year storm Logan Logan Ave S Outfall (Node O_2) CX 5644A downstream face of Logan Ave S Bridge 26.22 28.52 29.47 yes Williams Williams Ave S Outfall (Node O_1) CX 6502 downstream face of Williams Ave S Bridge 27.86 30.05 30.94 yes Wells Wells Ave S Outfall (Node O_3) CX 6974 upstream face of Wells Ave S Bridge 29.03 31.34 32.32 yes Main Main Ave S Outfall (Node O_4) CX 7483 at Main Ave S 30.13 32.37 33.33 yes Old City Hall Old City Hall Outfall (Node O_5) CX 8092 upstream face of Library 31.31 33.78 34.83 yes Black River Boundary Conditions Two boundary conditions within the Black River basin occur within the study area. For the Lake Basin, the boundary condition location is at Rainier Ave S and SW Sunset Blvd. The Shattuck Basin boundary condition is located at Shattuck Ave S and S 4th Place. Boundary conditions were evaluated based on prior modeling conducted for both Lake Ave S and 7th Street storm drainage improvement projects. The Draft SW 7th Street Storm Drainage Alternatives Analysis and Preliminary Design Memorandum and associated XPSWMM model (SAIC 2012) is based on the King County Runoff Time Series (KCRTS), future land use (or current land use if aerial imagery showed it was more impervious than allowed by zoning); land cover set to either impervious or till grass, Sea-Tac Region rainfall with a 1.0 scale factor, and a 15-minute City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 15 computational time step. Resulting hydrology was input into an XPSWMM hydraulic model to determine water surface elevations, identify areas of flooding, and develop design alternatives. The XPSWMM model begins (downstream) at the Naches Ave SW outfall to the Black River Pump Station forebay, extends up SW 7th Street to Burnett Ave S, and also includes contributing systems from Lake Ave S/Hardie Ave SW and Shattuck Ave S. The XPSWMM model does consider downstream tailwater effects from the unnamed “Stream A” connecting the Naches Ave SW outfall to the Black River Pump Station forebay. No calibration of the model was described. The modeling was revised to a 1-hour time step (Louis Berger 2016). Both the SAIC 2012 and Louis Berger 2016 model results were compared to establish boundary conditions for this study. Parametrix prepared a hydrologic and hydraulic report for the Lake Avenue South Storm System Project (February 2011) using similar model geometry, however used inlet control calculations to estimate water surface elevations near Rainier Ave S and SW Sunset Blvd. The XPSWMM node 80A_ABACAP is located at Rainier Ave S and SW Sunset Blvd, and is coincident with the Rainer Ave S and SW Sunset Blvd boundary. Node SH50_AN is located at Shattuck Ave S and S 4th Place, and is coincident with the Shattuck Ave S and S 4th Place boundary. There is a flow splitter or overflow riser that may engage during high flows and convey a portion of the flow down S 4th Place to an existing pump station, while lower flows are routed down Shattuck Ave S towards SW 7th Street. The flow splitter was evaluated during existing conditions modeling and is further described in Section 5.1. Select water surface elevations from prior reports (Louis Berger 2016, SAIC 2012, and Parametrix 2011) are summarized in Table 12. While prior reports used different models, inputs, and assumptions than present modeling, values were compared to determine if a rating curve could be applied to each outfall. As shown by varying data points in Table 12, the rating curve methodology was not reasonable. Instead, varying fixed backwater levels were input into XPSWMM and the model output was compared to prior model output and City observations. Table 12 Prior Modeling Results for 25-year Storm Basin Location (node) Ground Elevation (feet) Maximum Water Surface Elevation (feet) Flow (cfs) Flow Frequency Reference Lake Rainier Ave S and SW Sunset Blvd (Old Node: 80A_ABACAP; XPSWMM Node: E_500082) 30.22 23.3 10.1 25-year Louis Berger 2016 20.7 21.0 2-year SAIC 2012 28.8 17.0 10-year SAIC 2012 26.9 17.0 25-year SAIC 2012 29.2 15.3 100-year SAIC 2012 19.5 23.5 25-year Parametrix 2011 Shattuck Shattuck Ave S and S 4th Place (Old Node: SH50_AN; XPSWMM Node E_166498) 28.31 19.0 18.3 25-year Louis Berger 2016 19.1 8.2 2-year SAIC 2012 24.5 10.2 10-year SAIC 2012 24.9 11.7 25-year SAIC 2012 25.6 36.2 100-year SAIC 2012 Note: 1) Elevations are based on the North Atlantic Vertical Datum 1988 (NAVD 88). City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 16 For the Lake Basin, three fixed backwater elevations at the basin outfall were selected for initial modeling and include elevation 26.0, 23.3, and 19.5. Elevation 26.0 was thrown out due to overpredicted flooding. Elevations 23.3 and 19.5 were further evaluated during existing conditions modeling. Elevation 19.5 is approximately equal to the inlet control headwater elevation of the downstream-most pipe in the model network. As further described in Section 5, the recommended fixed backwater elevation for the Lake Basin is 19.5. For the Shattuck Basin, two fixed backwater elevations were initially evaluated, including elevation 19.0 feet and elevation 0.0 feet. The use of elevation 19.0 feet resulted in unstable model output; however, the use of elevation 0.0 feet, allowed XPSWMM to calculate normal flow within the downstream-most pipe, which resulted in a water surface elevation of 18.98 feet during a 25-year flow. The fixed backwater elevation was also estimated assuming an inlet control condition on the downstream-most pipe within the model network. The results were found to be similar, therefore a fixed backwater elevation of 0.0 feet was assigned to the Shattuck Basin. Table 13 summarizes the fixed backwater elevations for the Lake and Shattuck Basins draining towards the Black River. Table 13 Black River– Outfall Boundary Conditions Basin Location (node) Fixed Backwater Elevation at Outfall (feet) Tide gate? (yes/no) 10-year storm 25-year storm 100-year storm Lake Rainier S & Sunset (Node E_500082) 23.0 19.5* 23.3 19.5* 23.3 19.5* no Shattuck Shattuck & 4th Place (Node E_166498) 0 0 0 no Note: *Recommended value until further information is available, see Section 5 4.3.5 Junction Loss Coefficients Model results for existing conditions modeling do not include entrance and exit losses through a catch basin or manhole. Many of the prior models conducted in the project vicinity did not include junction losses and since many of the other model inputs for this study are considered conservative, junction losses were not applied to existing conditions. To evaluate model sensitivity as it relates to loss coefficients, the 25-year existing conditions storm was run for the Lake Basin with and without loss coefficients presented in Table 14. In comparing the results where flooding at a particular node was occurring without consideration of junction losses, the flood duration only slightly increased. One additional node was reported to flood within the Lake Basin. It was concluded that since only a slight increase in flooding was observed through the use of loss coefficients for existing conditions modeling, that loss coefficients would not be implemented for existing conditions modeling. Loss coefficients will be included for modeling of new conveyances for alternative solutions (or proposed conditions). Recommended loss coefficients for are presented in Table 14. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 17 Table 14 Loss Coefficients – Existing Stormwater System Loss Loss Coefficient, K Reference Selected Value for Model Comparison Entrance, upstream most manhole 0.1 to 0.5 for smooth to abrupt pipe entrance; 0.5 for inlet, straight run, square edge 1, 3, 5 Entrance Loss: 0.15 Straight flow through a junction 0.15-0.26 for access hole, straight run 3, 4 Entrance Loss: 0.15 90-degree bend, no shaping 1.0-1.1 (total loss through junction) 3,4 Exit Loss: 0.85 120-degree bend with no special shaping 0.6 to 0.85 (total loss through junction) 3, 5 Exit Loss: 0.45 Contraction loss, no bend angle (Ѳ=0) and V2>V1 or D1>D2 0.1 for gradual contraction to 0.5 for abrupt contraction 5 Entrance or Exit Loss: 0.5 Expansion Loss, no bend angle (Ѳ=0) and V1>V2 or D2>D1 0.2 for rounded corner to 1.0 for abrupt entrance 5 Entrance or Exit Loss: 0.5 Exit to Manhole 0.35 4 Not used Exit to Outfall/Culvert 1.0 2, 3 Exit Loss: 1.0 (at Cedar River Outfalls) References: 1) Brater et al 1996 2) Lindeburg 2005 3) FHWA 2013 4) SAIC 2012 5) XP Solutions 2015 4.3.6 Gutter Flow (Overflow Links) Overflow links were added to the existing conditions models to evaluate the extent of flooding within the existing system for the 10-, 25-, and 100-year storms. The overflow links were represented by a trapezoidal channel with the invert located at the existing node’s rim elevation. A six-inch tall curb was included, which added six inches to the node’s rim elevation. The gutter cross section was comprised of an 18-inch bottom width, one vertical side slope and one 2% side slope. 4.3.7 Sensitivity Analysis Prior hydrologic modeling within the City of Renton has been conducted KCRTS and routed hydraulically using XPSWMM. KCRTS is no longer supported by King County. Calibration data are not available for the study area and prior models have not been calibrated. For these reasons, it was determined that a representative basin within the study area would selected for a brief sensitivity analysis and comparison to other models. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 18 As shown in Table 12, prior analysis of 25-year peak flows estimated using KCRTS, have ranged from 10.1 cfs (Louis Berger 2016) to 23.5 cfs (Parametrix 2011). For this analysis, the initial 25-year peak flow, calculated using SBUH for the Lake Basin, was 56.5 cfs prior to flow routing through the basin conveyance pipe network using XPSWMM. With flow routing and an assigned fixed backwater elevation of 23.3 feet at the outfall, the calculated 25-year basin outflow was 33.8 cfs. Flooding of several nodes occurred during this model run. The model reported more flooding than the City has observed; therefore, several input parameters were further evaluated to test for model sensitivity to a particular parameter. SBUH flows were also compared with flows generated using the Western Washington Hydrology Model (WWHM) for comparative purposes. The sensitivity analysis concluded that several inputs were overly conservative and were adjusted within the limits of the model. Model sensitivity results are provided in Appendix A. Input values provided in this Section represent the conclusions made during the model sensitivity analysis. 5. Model Results 5.1 Existing Conveyance System Nine XPSWMM models were run to evaluate the existing conditions conveyance system, including: 1. 10-year, no overflow links, fixed backwater elevation for Lake Basin = 23.0 feet 2. 10-year, with overflow links, fixed backwater elevation for Lake Basin = 23.0 feet 3. 25-year, no overflow links, fixed backwater elevation for Lake Basin = 23.3 feet 4. 25-year, with overflow links, fixed backwater elevation for Lake Basin = 23.3 feet 5. 100-year, no overflow links, fixed backwater elevation for Lake Basin = 23.3 feet 6. 100-year, with overflow links, fixed backwater elevation for Lake Basin = 23.3 feet 7. 10-year, no overflow links, fixed backwater elevation for Lake Basin = 19.5 feet 8. 25-year, no overflow links, fixed backwater elevation for Lake Basin = 19.5 feet 9. 100-year, no overflow links, fixed backwater elevation for Lake Basin = 19.5 feet While the City’s design requirements include conveyance of the 25-year storm for existing systems, the 10- year storm was included in this evaluation to help demonstrate the severity of a capacity or flooding problem. During the 10- and 25-year storms, several nodes were found to overtop the rim. Where water overtops the rim of a catch basin during a 10- or 25-year storm, these nodes are out of compliance with the City’s requirements. There are several isolated low areas where ponding occurs during the 10- and 25-year storms. Overflow links were added to the models to determine depth of ponding within a curb and gutter system and help evaluate the extent of flooding. Overflow links were also added to the 100-year storm model to evaluate conditions where flooding occurs and determine if 100-year flooding causes increased or excessive flood concerns. Near the Outfall Conveyance Boundary for the Shattuck Basin (Node E_166500 shown on Figure 5), there is a flow splitter previously described in Section 4.3.4. The flow splitter is shown on Record Drawings for the Rainier Avenue S (SR 167) Improvements Project Phase 1 Shattuck Ave S Stormwater Bypass (DMJM Harris 2010). Sheet SD07, “Storm Drainage & Utilities Details” shows detail CB#10 that includes an 18- inch diameter riser within an 84” Type 2 catch basin. The rim elevation of the catch basin is shown at elevation 28.3 feet, and the invert of the sheer gate is shown at elevation 22.46. The elevation at the top of the over flow riser is not labeled, however it is shown 10 inches lower than the inside of the catch basin City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 19 structure. In the fall of 2017, City crews observed CB#10, measured down to the top of the over flow riser, and found it to be three-feet below the rim elevation of 28.3 feet, or approximately elevation 25.3 feet. The XPSWMM model for the existing conditions 25-year storm was analyzed to determine if storm flows would flow over the riser and be directed towards the pump station. The model shows that the hydraulic grade line (HGL) in CB#10 is approximately elevation 21.3, approximately four-feet below the over flow riser, so the flow splitter is not being engaged, and storm flows are not leaving the system towards the pump station. The flow splitter was therefore not included in the model geometry. 5.1.1 Existing Conveyance System Deficiencies Combined results from six models (numbers 1 through 6, above) were used as input to Figure 6, Existing System Deficiencies. These models assumed fixed backwater values (ranging from 23.0 to 23.3) for the three candidate storms, with and without gutter flow. Figure 6 shows pipe segments in green that do not have adequate capacity to convey the 10-year storm. Pipes shown in orange are pipes that do not have adequate capacity to convey the 25-year storm. Pipes shown in black have adequate capacity for the 100- year storm. After reviewing Figure 6 with the City, it was determined that the fixed backwater elevation of 23.3 feet at the outfall to the Lake Basin may be overly conservative. The existing stormdrain within Lave Ave S is not currently causing flooding problems for the City. Also, the existing stormdrain along S 2nd Street between Shattuck Ave S and Lake Ave S is not currently causing flooding problems. For these reasons, a lower tailwater elevation of 19.5 feet was selected from Table 12. Figure 6A was developed using results from three models (numbers 7 through 9, above). Two stormwater trunk lines within Lake Sub-basins, Lake-1 and Lake-2, appear to be undersized. These are on the edge of the study area and not within the core downtown area. The City plans to monitor these areas for flooding before initiating the design phase. The fixed backwater elevation of 19.5 feet for the Lake Basin is recommended for both existing conditions modeling and modeling of proposed alternatives. 5.1.2 Select Model Results Select model results are provided in Appendix B and include a plan map showing profile locations, stormwater profiles, and XPSWMM output tables for the 25-year existing conditions model (without overflow links and fixed backwater elevation equal to 19.5). This model was selected for presentation in the appendix because it appears to have the most reasonable inputs and assumptions. Output tables are organized by pipe profile and show the depth and duration of flooding at a particular node. Flooded nodes are highlighted in yellow. Model output tables for the 10- and 100-year storms are also included in Appendix B. Stormwater capacity concerns occur at the following locations:  Lake-1 along S Tillicum Street includes undersized 8-inch pipe and two low areas  Lake-2 along S Tobin Street includes an undersized 18- to 24-inch trunk  Lake-4b presently routes flows across private property and into the stormdrain within Lake Ave S. Future plans will route stormwater flows south along Rainier Avenue to the Lake-5 sub-basin.  Lake-8a and 8b within the SPU Water Main Right-of-Way (ROW) includes undersized pipe  Shattuck-2 and Shattuck-4/5 along Shattuck Avenue includes an undersized 12-inch trunk  Shattuck-3 along S 4th Street includes an undersized 12-inch trunk  Logan-1 near Airport Way includes an undersized 12-inch trunk City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 20  Logan-2c includes isolated ponding due to a low spot.  Logan-3a/3d along 3rd Street and Burnett Ave includes an undersized 8-inch trunk  Williams-1/2 along Burnett and Tillicum includes an undersized 8-inch trunk and isolated low areas  Williams-3 along Williams includes an undersized 8-inch trunk  Old City Hall-1/2 includes an undersized 12-inch trunk along 2nd Street 5.1.3 Problem Area Prioritization Problem areas listed in order from high to low priority are as follows:  Logan-3a/3d along 3rd Street and Burnett Ave – The City’s Transportation Group is planning intersection improvements in this vicinity. Planning and design are underway.  Williams-1/2 along Burnett and Tillicum – Recent flooding of a residential apartment complex along Burnett due to the finished floor elevation being lower than the catch basin rim elevation in the ROW.  Williams-3 along Williams – This project would be combined with Williams-1/2 project.  Shattuck-2 and Shattuck-4/5 along Shattuck Avenue – This pipe run is in disrepair and is undersized.  Shattuck-3 along S 4th Street – This project may be included with Shattuck-2 and Shattuck-4/5 project.  Lake-8a and 8b pipe is within the SPU ROW and is undersized. City desires to install new trunk lines in S 3rd Street, which would be easier to maintain in the long-term. This project may be included with Shattuck-2 and Shattuck-4/5 project.  Logan-1 near Airport Way is outside the core downtown area, but pedestrian trail improvements are underway that could include conveyance pipe upsizing.  Old City Hall-1 and -2 – The Old City Hall property is targeted for redevelopment and work could include upsizing pipe within S 2nd Street to improve long-term conveyance.  Lake-1 and Lake-2 are outside the core downtown area and these areas are not targeted for near- term development. These areas will be monitored during storm events. 5.2 Alternatives Analysis 5.2.1 General The alternatives analysis included the following:  Consideration of existing and potential flow routes with respect to downtown improvements. The City’s preference is to maintain drainage routes and discharge locations; in other words where possible, “keep water where it currently goes”.  Conceptual design of alternatives to include system sizing and layout for the proposed improvements (pipeline conveyance system only). The conceptual design was performed to a sufficient level of detail to develop and define project improvements (including identifying general elements and features required) to determine constraints related to feasibility, permitting, constructability, and other factors.  Alternative conveyance system alignments were modeled using XPSWMM.  Relative/qualitative cost and advantages and disadvantages of each alternative.  Preferred alternative recommendation. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 21 5.2.2 Alternative 1 Alternative 1 includes upsizing conveyances along existing alignments where deficiencies occur. Conveyance pipe improvements include matching the existing pipe alignment and slope, and maintaining existing conveyance outfall locations. Stormwater trunk line improvements for Alternative 1 are shown on Figure 7 and include the following:  Lake-1 along Tillicum (undersized 8-inch pipe and two low areas)  Lake-2 along Tobin (undersized 18- to 24-inch trunk)  Lake-4b: Route south along Rainier Avenue to the Lake-5 sub-basin  Lake-8 within the SPU Water Main Right-of-Way (ROW)  Lake-4 along Lake Ave (upgrades are needed in response to the additional flow from Lake-4b and Lake-8 upgrades)  Shattuck-2 and Shattuck-4/5 along Shattuck Avenue (upsize 12-inch trunk)  Shattuck-3 along S 4th Street (upsize 12-inch trunk)  Logan-1 near Airport Way (upsize 12-inch trunk)  Logan-2c (no upgrades). Note: isolated ponding due to low spot and backwater caused by Logan- 3a/3d upgrades. See attached Output Table for more information, including flood depth (3 inches) and duration (27 minutes). City will monitor rather than upsize due to limited flooding.  Logan-3a/3d along 3rd Street and Burnett Ave (upsize 8-inch trunk)  Williams-1/2 along Burnett and Tillicum (upsize 8-inch trunk). Notes: o Isolated ponding occurs at two locations due to low areas. See Appendix B for output tables that include flood depth (2.5 inches) and duration (30 minutes). Flooding would be alleviated by upsizing the 12-inch outfall. o Narrow alley along Tillicum; may be difficult/expensive to install 24-inch replacement pipe.  Williams-3 along Williams (upsize 8-inch trunk)  Old City Hall-1/2 (upsize 12-inch trunk along 2nd Street) Alternative 1, 2, and 3 assume a fixed backwater elevation equal to 19.5 feet for the Lake Basin. Due to limited information available for calibration of this Basin, it is recommended that sub-basins Lake-1 and Lake-2 be observed during storm events to determine the extent and severity of flooding near S Tillicum Street and S Tobin Street near Lake Ave S. Isolated flooding of low areas occurs near Williams-1. Mitigation options could include:  Monitor outfall and potentially upsize the outfall when it needs replacement in the future  Install detention pipe (similar to Alternative 2)  Replace outfall (see Alternative 3) Material quantities for Alternative 1 conveyance system upgrades are summarized in Table 15. Table 15 Material Quantities - Alternative 1 Pipe (linear feet) 8,505 48-inch Manhole, for 12- to 24-inch diameter pipe (each) 44 72-inch Manhole, for 36-inch diameter pipe (each) 14 Excavation (cubic yards) 13,510 City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 22 5.2.3 Alternative 2 Key differences between Alternatives 1 and 2 include rerouting sub-basin Lake-8 to the Shattuck Basin and adding a new 36-inch trunk between Burnett Ave S and Williams Ave S within the Williams Basin. Alternative 2 improvements are shown on Figure 8 and include Alternative 1 improvements, except for the following:  Lake-8: Size a new trunk along 3rd Street from Logan Ave to Shattuck Ave to collect the Lake-8 Sub-basin drainage area along SPU ROW between 2nd and 3rd Streets. Size connections along Whitworth Ave and Morris Ave from SPU ROW to 3rd Street. Route Lake-8 to the Shattuck Basin. The stormwater line within the SPU Cedar River Pipeline corridor (Lake-8a) will remain as a redundant system; however, it was disconnected for modeling purposes.  Lake Basin: Note flooding of four nodes. See Appendix B output table for more information. o Lake-2 flooding at three nodes. Depth and duration are 8 inches and 61 minutes, respectively. o Lake-4 flooding at one nodes. Depth and duration are less than one inch and 15 minutes, respectively.  Shattuck-2 and Shattuck-4/5: Upsize trunk to structure E_133171 as needed to relieve flooding along connecting mains. Avoid new crossings of the SPU Water Mains.  Williams-1/2 (Burnett Ave) and Williams-3 (Williams Ave) – add new pipe connection from Burnett to Williams along Tobin Street, because Tobin Street has a wider ROW than Tillicum. Leave the existing 8-inch pipe in Tillicum Street. Notes: o Isolated ponding occurs at four low areas due to the undersized 12-inch outfall o Williams-1 flooding at three nodes. Depth and duration are 1.5 inches and 36 minutes o Williams-2 flooding at one nodes. Depth and duration are less than one inch and 12 minutes o Additional pipes require replacement due to elevation differences, because Burnett pipe (Williams-2) is deeper than the trunk in Williams (Williams-3) Material quantities for Alternative 2 conveyance system upgrades are summarized in Table 16. Table 16 Material Quantities - Alternative 2 Pipe (linear feet) 8,034 48-inch Manhole, for 12- to 24-inch diameter pipe (each) 37 72-inch Manhole, for 36-inch diameater pipe (each) 12 Excavation (cubic yards) 12,938 5.2.4 Alternative 3 Alternative 3 includes similar revisions to the Lake-8 sub-basin as Alternative 2; however, this alternative includes routing sub-basin Lake-8 down S 3rd Street to the Lake Basin. Improvements within the Williams Basin include upsizing the 12-inch diameter outfall to the Cedar River to alleviate upstream flooding. Alternative 3 improvements are shown on Figure 9 and include Alternative 2 improvements, except for the following:  Lake-8: Extend the new trunk on 3rd Street, starting at node P_Node2325 (at the intersection of Whitworth and 3rd Street) and connect to the existing storm line on 3rd Street at structure E_135876. Upsize the existing pipe to E_178159. Shattuck-2 remains flowing south along Shattuck Ave due to deeper pipe elevations within Shattuck Ave. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 23  Lake-4: Note increased flooding as compared with Alternative 2 (one additional node)  Williams: Upsize the 12-inch outfall to alleviate flooding and check pipe sizes in Williams sub- basins Material quantities for Alternative 3 conveyance system upgrades are summarized in Table 17. Table 17 Material Quantities - Alternative 3 Pipe (linear feet) 8,975 48-inch Manhole, for 12- to 24-inch diameter pipe (each) 45 72-inch Manhole, for 36-inch diameter pipe (each) 8 Excavation (cubic yards) 12,205 5.3 Preferred Alternative The Preferred Alternative, presented on Figure 10, includes a combination of Alternatives 1, 2, and 3. Preferred Alternative improvements include:  Lake-1 along Tillicum (undersized 8-inch pipe and two low areas)  Lake-2 along Tobin (undersized 18- to 24-inch trunk)  Lake-4b: Route south along Rainier Avenue to the Lake-5 sub-basin  Lake-8: Size a new trunk along 3rd Street from Logan Ave to Shattuck Ave to collect the Lake-8 Sub-basin drainage area along SPU ROW between 2nd and 3rd Streets. Size connections along Whitworth Ave and Morris Ave from SPU ROW to 3rd Street. The stormwater line within the SPU Cedar River Pipeline corridor (Lake-8a) will remain as a redundant system; however, it was disconnected for modeling purposes.  Shattuck-2 and Shattuck-4/5: Upsize trunk to structure E_133171 to relieve flooding along connecting mains. Avoid new crossings of the SPU Water Mains.  Shattuck-3 along S 4th Street (upsize 12-inch trunk)  Logan-2c (no upgrades). Note: isolated ponding due to low spot and backwater caused by Logan- 3a/3d upgrades. See Appendix B output table for more information, including flood depth (3 inches) and duration (27 minutes). City will monitor rather than upsize due to limited flooding.  Logan-3a/3d along 3rd Street and Burnett Ave (upsize 8-inch trunk)  Williams-1/2 (Burnett Ave) and Williams-3 (Williams Ave): o Add new pipe connection from Burnett to Williams along Tobin Street, because Tobin Street has a wider ROW than Tillicum o Leave the existing 8-inch pipe in Tillicum Street o Note that additional pipes require replacement due to elevation differences, because Burnett pipe (Williams-2) is deeper than the trunk in Williams (Williams-3) o Upsize the 12-inch outfall to alleviate flooding and check pipe sizes in Williams sub-basins For improvements within sub-basin Lake-8, Alternative 2 was preferred for the following reasons:  Fewer pipe replacements than Alternatives 1 and 3.  Draft Environmental Report notes existing leaking underground storage tanks near 3rd Street and Lake Ave S. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 24 For improvements within the Williams Basin, the preferred alternative includes upsizing storm water trunk lines within Burnett Ave S and Williams Ave S, replacing the 12-inch outfall to the Cedar River with a 24- inch outfall, and providing a redundant storm trunk between Burnett Ave S and Williams Ave S along S Tobin Street. The preferred alternative proposes routing storm flows from sub-basin Lake-8 to the Shattuck system. A brief analysis was conducted to evaluate the capacity of the conveyance system downstream of the Shattuck Basin outfall conveyance boundary located at Shattuck Ave S and S 4th Place (Node E_166500). Peak flow for the 25-year storm existing conditions model (with overflow links) is 19.9 cfs, while the proposed alternative 25-year peak flow is 30.8 cfs. The proposed alternative includes an increase in peak flow to the Shattuck trunk of approximately 11 cfs during the 25-year storm. Two prior reports (GHD 2010 and GHD 2011) describe the Shattuck Avenue Diversion Modeling, which was conducted to design the new 48-inch diameter pipe along Shattuck Ave S between S 4th Place and S 7th Street. The design assumed the Shattuck system would receive runoff from 54 acres of contributing area. The 54 acres were made up of four historic sub-basins: Basin AL (5.05 acres), Basin AG (14.06 acres), Basin V2 (24.04 acres), and Basin AN (11.22 acres). The four sub-basins were modeled using KCRTS assuming “future conditions” represented by percent impervious area assumptions of 78%, 94%, 83%, and 75% for Basins AL, AG, V2, and AN, respectively. The resulting weighted average is 54 acres of 84% impervious surface, or 46 acres of impervious contributing area. Comparing the GHD design assumptions for the 48-inch trunk to the preferred alternative for this study, there are five Shattuck sub-basins plus Lake-8 that represent a total area of 42 acres. The weighted average impervious surface is 89%, resulting in 37 acres of impervious contributing area flowing to the Shattuck system. Since the original design of the Shattuck Avenue Diversion assumed a greater total contributing area (54 versus 42 acres) and a greater impervious contributing area (46 versus 42 acres), the system downstream of Shattuck appears to have adequate capacity for the additional flows from the Lake-8 sub-basin. Table 18 provides a materials quantity summary for Alternatives 1, 2, 3, and the Preferred Alternative. Alternative 2 includes the shortest length of pipe replacements and the fewest new manholes (or catch basins). Alternative 3 includes the longest length of pipe replacements and the greatest number of new manholes. Alternative 1 has the highest volume for excavation while the Preferred Alternative has the lowest volume for excavation. Based on total length of pipe replacements and quantity of structures needed, Alternative 2 appears to have the lowest project cost, followed by the Preferred Alternative. However, the Preferred Alternative includes replacement of the Williams Ave S outfall to the Cedar River, which may result in costs higher than Alternative 2, but lower than Alternative 3. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 25 Table 18 Materials Quantity Summary Material Type Alternative 1 Alternative 2 Alternative 3 Preferred Alternative Pipe, total (linear feet) 8,505 8,034 8,975 8,123 12-inch diameter (linear feet) 1,383 1,893 2,229 2,399 18-inch diameter (linear feet) 3,776 2,535 4,886 3,273 21-inch diameter (linear feet) 235 235 235 235 24-inch diameter (linear feet) 1,502 1,789 595 1,185 36-inch diameter (linear feet) 1,610 1,583 1,031 1,031 Manhole, total (each) 58 49 53 50 48-inch Manhole, for 12- to 24- inch diameter pipe (each) 44 37 45 42 72-inch Manhole, for 36-inch diameter pipe (each) 14 12 8 8 Excavation (cubic yards) 11,253 10,783 10,351 9,792 24-inch Outfall Replacement at Williams Ave S (each) 1 1 Qualitative Comparison of Costs (lowest -$ to highest - $$$$) $$ $ $$$$ $$$ 6. Regulatory Considerations for Future Phases This section includes a review of the regulatory environment related to the existing conditions within the study area and a review of standards and requirements for improvements to the stormwater conveyance system to handle anticipated roadway modifications and future development per current zoning. Other potential design requirements related to future redevelopment have also been identified and includes a qualitative assessment of general regulatory requirements. It is assumed that specific project thresholds for future development projects will be handled independent from this scope of work. Reference documents related to the regulatory setting include, but are not limited to:  Renton Municipal Code (RMC), Title IV Development Regulations  2017 City of Renton Surface Water Design Manual (COR SWDM)  COR Comprehensive Plan (June 22, 2015)  Zoning Map (July 1, 2015)  City of Renton Standard Plans  Federal Emergency Management Agency Flood Insurance Study (2010) 6.1 General Requirements General regulations related to development and redevelopment within the study area include:  Shoreline Master Program Regulations (RMC 4-3-090) which apply to the Cedar River. Shoreline lands include areas within 200 feet, as measured on a horizontal plane, from the Ordinary High Water Mark (OHWM), or lands within 200 feet from floodways, whichever is greater. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 26  Airport related height and use restrictions (RMC 4-3-020). The study area is located within the Renton Municipal Airport Safety Zones or Airport Influence Area. Height and land use activities are regulated within this area as required by the Federal Aviation Authority.  Urban design regulations (RMC 4-3-100) are established in accordance with and to implement policies established in the Land Use Element of the Comprehensive Plan.  City-Wide Property Development Standards (RMC 4-4) includes standards governing site development of property City-wide, such as parking, landscaping, fencing, and others.  Building and Fire Prevention Standards (RMC 4-5) provides structural and design information.  Street and Utility Standards (RMC 4-6) includes development-related requirements for water, sewer, storm drainage, and street construction.  Work within the floodplain of the Cedar River will be subject to FEMA requirements. The City’s GIS and 1995 FEMA FIRM show the Cedar River floodplain generally within or adjacent to the river levees within the project study area.  Work below the OHWM of the Cedar River will require permits and review through multiple agencies including but not limited to Washington State Department of Fish and Wildlife, Department of Natural Resources, Ecology, US Army Corps of Engineers, and the Muckleshoot Indian Tribe. 6.2 Drainage Requirements The proposed improvements for the Downtown Utility Improvements Project will include utility upgrades to stormwater, water, and wastewater systems and other impacted utilities. The construction of the utility improvements may be coordinated with other proposed improvement projects, such as roadway and intersection reconfigurations, to limit the length of construction impacts within the project limits. Regulations specific to drainage are described in RMC 4-6-030 Drainage (Surface Water) Standards. Drainage review is required when any proposed project is subject to a City of Renton development permit or approval and: 1. Would result in 2,000 square feet or more of new impervious surface, replaced impervious surface, or new plus replaced impervious surface; or 2. Would involve 7,000 square feet of land disturbing activity; or 3. Would construct or modify a drainage pipe or ditch that is 12 inches or more in size or depth or receives surface or stormwater runoff from a drainage pipe or ditch that is 12 inches or more in size or depth; or 4. Contains or is abutting a critical area designation; or 5. Is a single family residential development that would result in new impervious surface, replaced impervious surface, or new plus replaced impervious surface. Impervious area removed and replaced for the sole purpose of installing utilities is excluded from the threshold of replaced impervious area per the definition of replaced impervious surface in the COR SWDM. Utility related impacted areas are still considered land disturbing activities subject to the 7,000-square foot threshold. Maintenance only projects are exempt from drainage review per COR SWDM Section 1.1.1. 6.2.1 Drainage Review Types and Requirements There are five drainage review types (Simplified, Directed, Targeted, Full, and Large Project) that tailor the review process and application of drainage requirements to a project’s size, location, type of development, and anticipated impacts to the local and regional surface water system. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 27 COR SWDM Table 1.1.2.A: Requirements Applied Under Each Drainage Review Type identifies five different types of drainage reviews that may be required for a given project. The two likely drainage review types required for the Downtown Utilities Improvement Project are either the Targeted (Category 2) or the Full Drainage Review.  Targeted (Category 2) drainage review applies to projects that construct or modify a drainage pipe/ditch that is 12 inches or larger or receive runoff from a 12 inch or larger drainage pipe or ditch. This requirement would apply to conveyance system or other utility improvements in the right-of-way.  Full Drainage Review are required for development projects resulting in 2,000 square feet or more of new plus replaced impervious surface or greater than 7,000 square feet of land disturbing activity. The Downtown Utility Improvements Project will likely require a Full Drainage Review based on anticipated exceedance of land disturbing activity thresholds. Core requirements for Targeted (Category 2) and Full Drainage Review are presented in Table 19. Table 19 Drainage Review Core Requirements Core Requirement Drainage Review Type Targeted (Category 2) for Utility Improvements in Right-of-Way Full for Downtown Redevelopment on Private Property 1. Discharge at the natural location X X 2. Off-site analysis X X 3. Flow control facilities X 4. Conveyance system X X 5. Construction stormwater pollution prevention X X 6. Maintenance and operations X X 7. Financial guarantees and liability X X 8. Water quality facilities X 9. On-site Best Management Practices (BMPs) X Project-specific requirements related to select Core Requirements 3, 4, 8, and 9 are described below. The other five core requirements do not vary for the type of project modification proposed, such as inclusion of roadway improvements, once the minimum disturbed area thresholds are exceeded. Core Requirement #3 (Flow Control Requirements) The COR SWDM Section 1.2.3 provides the criterion for flow control facilities. Projects are exempt from flow control if they meet the following requirements:  Less than 5,000 square feet of new plus replaced impervious surface will be created; and  Less than ¾ acres of new pervious surface will be added. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 28 6.2.2 Direct Discharge Exemption Development within areas draining to the Cedar River may be covered under a Direct Discharge Exemption. According to COR SWDM Section 1.2.3.1, an on-site drainage area is exempt from the flow control facility requirement if the area drains to the Cedar River downstream of Taylor Creek, and meets the following criteria: 1. The flow path from the project site discharge point to the edge of the 100-year floodplain of the major receiving water will be no longer than a half mile, and 2. The conveyance system between the project site and the major receiving water will extend to the OHWM, and will be comprised of manmade conveyance elements (pipes, ditches, etc.), and will be within public right-of-way or a public or private drainage easement, and 3. The conveyance system will have adequate capacity to convey the 25-year peak flow (per Core Requirement #4, Conveyance System), for the entire contributing drainage area, assuming build- out conditions, and 4. The conveyance system will be adequately stabilized to prevent erosion, and 5. The direct discharge proposal will not divert flows from or increase flows to an existing wetland or stream sufficient to cause a significant adverse impact. 6.2.3 Modeling Requirements The SBUH Method was selected for use in hydrologic modeling for the conveyance capacity analysis based on COR SWDM Table 3.2: Acceptable Uses of Runoff Computation Methods. Per the COR SWDM, SBUH is acceptable for peak flow conveyance sizing for tributary areas greater or equal to 10 acres and where no storage routing is performed; and SBUH is acceptable for use in downstream analysis for projects in Full or Targeted Drainage Review where tributary areas are greater or equal to 10 acres if no storage routing is performed. The Rational method is also allowed by the COR SWDM if no storage routing is performed. For future development projects related to downtown redevelopment, hydrologic modeling using continuous hydrologic analysis using an “approved model” will be required, primarily for the design of flow control facilities. COR SWDM approved models include the Western Washington Hydrologic Model (WWHM) and MGS Flood. Core Requirement #4 (Conveyance Design Requirements) The COR SWDM Section 1.2.4.1 provides the following criterion for the design storm and modeling requirements for the existing and proposed conveyance systems:  Existing and new pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for on-site tributary areas and existing conditions for any offsite tributary areas.  Pipe system structures may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a severe flooding problem or severe erosion problem.  Any overflow occurring on-site for runoff events up to and including the 100-year event must discharge at the natural location for the project site. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 29 For this project, modeling conducted to evaluate the existing stormwater system will be based on future build-out conditions allowed by current zoning designations. Core Requirement #8 (Water Quality Facilities) The COR SWDM Section 1.2.8 provides criterion for the design of water quality (WQ) facilities for proposed projects, including redevelopment projects. WQ facilities are required to treat runoff from new and replaced pollution-generating impervious surfaces and new pollution-generating pervious surfaces. There are four possible exemptions from the requirement to provide a WQ facility per Core Requirement #8, including:  Surface Area Exemption: a) Less than 5,000 square feet of new plus replaced pollution generating impervious surface (PGIS) that is not fully dispersed, and b) Less than ¾ acre of new pollution generating pervious surface (PGPS) that is not fully dispersed.  Surface Area Exemption for Transportation Redevelopment Projects: a) Total new impervious surface within the project limits is less than 50% of the existing impervious surface, and b) Less than 5,000 square feet of new PGIS that is not fully dispersed will be added, and c) Less than ¾ acre of new PGPS that is not fully dispersed will be added.  Cost Exemption for Parcel Redevelopment Projects: d) The total valuation of the project’s proposed improvements (including interior improvements and excluding required mitigation improvements) is less than 50% of the assessed value of the existing site improvements, and e) Less than 5,000 square feet of new PGIS that is not fully dispersed will be added, and f) Less than ¾ acre of new PGPS that is not fully dispersed will be added.  Soil Treatment Exemption: A proposed project is exempt if the runoff from PGIS is infiltrated in soils that meet the “groundwater protection criteria” outlined in Section 1.2.8.1 of the COR SWDM. The COR SWDM describes two types of WQ treatment, Basic and Enhanced Basic WQ treatment. Basic WQ Treatment Areas are designated by the City where a general, cost-effective level of treatment is sufficient for most land uses. Many direct discharges only require Basic WQ Treatment. Some land uses will need an increased level of treatment, Enhanced Basic WQ Treatment, because they generate high concentrations of metals in stormwater runoff and acute concentrations of metals in streams are toxic to fish. Enhanced Basic WQ is required if 50% or more of the runoff that drains to any proposed WQ facility is from one or more of the following land uses: 1. Commercial, industrial, or multifamily land use. 2. A road with an expected average daily traffic (ADT) count of 7,500 or more vehicles. Based on zoning, most of the land targeted for redevelopment is anticipated to require Enhanced Basic WQ treatment during redevelopment. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 30 The Cedar River Downstream of Taylor Creek confluence qualifies as a major receiving water that has been determined by City to be safe for the direct discharge of increased runoff from a proposed project without a flow control facility. Major receiving waters are also considered safe for application of Basic WQ treatment in place of otherwise required Enhanced Basic WQ treatment, except where the receiving water is either (1) listed as impaired for metals or organic pollutants according to Ecology’s Water Quality Assessment categories 2, 4, or 5, and/or (2) where subject to any other local, state, or federal cleanup plan. According to the Washington State Department of Ecology Water Quality Atlas map (https://fortress.wa.gov/ecy/waterqualityatlas/map.aspx?CustomMap=y&RT=0&Layers=23,29&Filters=n,n,n ,n), the Cedar River within the study area is listed as Category 2 for Mercury. Therefore, areas draining to the Cedar River will require Enhanced Basic WQ treatment during development/redevelopment. Receiving waters that are fish bearing require Enhanced Basic WQ treatment; therefore, areas draining to the Black River Basin will require Enhanced Basic WQ treatment during development/redevelopment. Based on this initial review, unless an exemption applies, it appears that Enhanced Basic WQ treatment will be required for development/redevelopment projects within the study area. Core Requirement #9 (On-Site BMPs) The COR SWDM Section 1.2.9 describes on-site BMPs as methods and designs for dispersing, infiltrating, or otherwise reducing or preventing development-related increases in runoff at or near the sources of those increases. On-site BMPs include, but are not limited to, preservation and use of native vegetated surfaces to fully disperse runoff; use of other pervious surfaces to disperse runoff; roof downspout infiltration; permeable pavements; bioretention; limited infiltration systems; and reduction of the development footprint. Exemption criterion for Core Requirement #9 include: 1. Basic Exemption a. Less than 2,000 square feet of new plus replaced impervious surface will be created, and b. Less than 7,000 square feet of land disturbing activity will occur. 2. Flow Control Facility Exemption – Any impervious surface served by an infiltration facility designed in accordance with the flow control facility requirement (Section 1.2.3.1), the facility implementation requirements (Section 1.2.3.2), and the design criteria for infiltration facilities (Section 5.2) is exempt from the on-site BMP requirement. 6.2.4 Outfall Improvements to Cedar River: Through hydrologic and hydraulic modeling conducted for this study, if conveyance improvements are found to be needed for one of the two Cedar River outfalls, environmental permitting and review with multiple agencies related to in-water work within the OHWM of the Cedar River will be necessary and mitigation may be required. Potential environmental permitting requirements are being evaluated separately for this project. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 31 Project Implementation Scenarios Summaries for Core Requirement 3, 8 and 9 are provided for three different project implementation scenarios of Utility Improvements, Coordinated Roadway Improvements and Regional Mitigation for Existing or Future Development. Core requirements for each scenario would need to be evaluated based on the proposed improvements. The following project implementation scenarios would likely include:  Flow Control Facilities (Core Requirement #3)  Water Quality Facilities (Core Requirement #8)  On-site BMPs (Core Requirement #9) Utility Improvements Only Scenario: If the project moves through construction based on implementation of utility improvements only, a Full Drainage Review would likely be necessary, based on the thresholds for land disturbing activities. For small, isolated projects, a Targeted Drainage Review might apply and should be evaluated on a case-by- case basis. Coordinated Roadway Improvements Scenario: If the utility improvements are combined with the anticipated roadway improvements to limit construction disturbances within the downtown core, then Core Requirement thresholds based on both projects would need to be addressed. A review of all Core Requirements would be necessary through a Full Drainage Review. Regional Mitigation for Existing or Future Development Scenario: The utility improvements project could provide flow control or water quality treatment as a stormwater retrofit effort or as a regional system to promote redevelopment within the downtown district. Regional or dispersed stormwater facilities could be integrated into the proposed utility and/or roadway improvement projects. This approach could allow for consolidation of flow control, water quality, and on-site BMP requirements. However, a review of all Core Requirements would still be necessary through a Full Drainage Review. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 32 7. References Brater et al 1996 Brater, King, Lindell, and Wei; Handbook of Hydraulics, Seventh Edition; 1996. COR SWDM 2016 City of Renton, Public Works Department, Surface Water Utility; City of Renton Surface Water Design Manual (COR SWDM); December 12, 2016. COR 2015 City of Renton, Comprehensive Plan, June 2015. DMJM Harris 2010 DMJM Harris | AECOM; Rainier Ave (SR 167) Improvements Project Phase 1 Shattuck Ave S Stormwater Bypass System Record Drawings; September 2010. FEMA 2010 Federal Emergency Management Agency (FEMA); Flood Insurance Study Number 53033CV002B, and Flood Insurance Rate Map, King County, Washington and Incorporated Areas; 2010. FHWA 2013 U.S. Department of Transportation, Federal Highway Administration; Hydraulic Engineering Circular No. 22, Third Edition, Urban Drainage Design Manual; September 2009, revised August 2013. GHD 2011 GHD; Rainier Avenue South Improvement Project – SW Grady Way to S 2nd Street, Surface Water Technical Information Report; November 2011. GHD 2010 GHD; City of Renton, Shattuck Avenue Stormwater Diversion Modeling Report; April 2010. KC SWDM 2016 King County Department of Natural Resources and Parks; King County, Washington, Surface Water Design Manual (KC SWDM); April 24, 2016. KC SWDM 1990 King County Department of Natural Resources and Parks; King County, Washington, Surface Water Design Manual (KC SWDM); January 9, 1990. Lindeburg 2005 Lindeburg, Michael; Civil Engineering Reference Manual, 10th Edition; 2005. Louis Berger 2016 Louis Berger; Draft Hardie Avenue SW - SW 7th Street Storm System Improvement Project, Supplemental Hydrologic and Hydraulic Analysis Report; February 2016. NRCS 2017 United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS); Web Soil Survey https://websoilsurvey.sc.egov.usda.gov/; accessed August 2017. Parametrix 2011 Parametrix; Hydrologic and Hydraulic Report, Lake Avenue South Storm System Project (H&H Report); February 2011. SAIC 2012 SAIC; Draft Alternatives Analysis and Preliminary Design Memorandum Report and Associated XPSWMM Model; July 2012. SWMMWW 2014 Washington State Department of Ecology, Stormwater Management Manual for Western Washington; December 2014. City of Renton Downtown Utility Improvements Conceptual Stormwater Design Report 33 SWMMWW 2001 Washington State Department of Ecology, Water Quality Program; Stormwater Management Manual for Western Washington; August 2001. Tetra Tech 2017 Cedar River 205 Levee System Interior Drainage Analysis Draft Report, April 2017. USACE 2004 U.S. Department of the Army, Corps of Engineers; Cedar River at Renton Flood Damage Reduction Operation and Maintenance Manual: Cedar River Section 205 (Renton, Washington); 2004. XPSWMM 2015 XP Solutions; XPSWMM Stormwater and Wastewater Management Model; 2015. FIGURES P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 1 Stormwater Study Area 11x17.mxd 11/15/2017 8:38:59 AM ctolentinoWILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST "J "J "J "J "J "J "J Cedar River C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 1STORMWATERSTUDY AREA N o v e m b e r 15 2017 0 400200 Scale in Feet © Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. BlackRiverDrainage CedarRiverDrainage Legend "J Outfall ConveyanceBoundary Pipe SPU Cedar River Pipeline King County EastsideInterceptor Project Study Drainage Area Parcels Black River Drainage Cedar River Drainage P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 2 Basin Delineation 11x17.mxd 11/9/2017 3:16:01 PM ctolentinoWILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST "J "J "J "J "J "J "J Cedar River VeteransMemorial Park Piazza CedarRiver Park Jones Park GatewayPark Tonkin Park Cedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail Lake Logan Wells Williams Main Old City Hall Shattuck C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 2BASINDELINEATION N o v e m b e r 15 2017 0 400200 Scale in Feet ©Legend "J Outfall ConveyanceBoundary Pipe Culvert King County EastsideInterceptor SPU Cedar River Pipeline Project Study Area Building Footprints Parks Water Body Lake Logan Main Old City Hall Shattuck Wells Williams Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 3 Sub-basin Delineation 11x17.mxd 11/15/2017 8:48:24 AM ctolentinoLake-7 Lake-1a Logan-1 Logan-2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST "J "J "J "J "J "J "J Cedar River VeteransMemorial Park Piazza CedarRiver Park Jones Park GatewayPark TonkinPark BurnettLinear Park Cedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail 12in CPEP8 i n PCP21in PCP 12in PCP12in PCP 12in PVC42in UNK 12in PCP 6in PCP 8in PCP1 2 i n CMP1 2in C P E P48in PCP12in CPEP12in UNK 12i n PVC18in PCP 8in CMP18in CPEP6in PVC1 2 i n CPEP12in UNK12in CPEP12in PCP 8in P C P 12in DI12in CPEP12in CPEPin12in CMP12in UNK12in CPEP18in UNK1 2 i n P C P12in PCP12in UNK12in UNK 12in PCP6in CPEP12in PC P12in PVC 8in PCP12in PCP12in UNK8in PVC12in PCP 18i n UNK12in UNK 8in UNK12in CPEP12in UNK24in UNK12in PCP18in PCP18in PCP 18i n CPEP12in UNK12i n UNK12in PCP8in DI1 2 i n CPEPin15in CPEP24in PCP6in PCP 12in UNK12in PCP24in PCP3 6 in C P E P 12in CPEP18in CPEP 8in PCP 8in PCP48in CPEP12in PCP 12in UNK 8in UNK24in PCP10in PCP12in CMP24in CPEP12in PCP60in CMPA8in UNK12in PCP 12in PCP12in PCP12in PCP 1 2 in P C P 1 2in U N K 12in PCP 12in PVC 1 2 in C M P 24in CPEP 12in PCP18in UNK12i n UNK8in PCP 8in PCP 8in PCP10in DI12in PCP 12in UNK18in UNK 8in PCP12in PCP10in CLAY -2 in CMP 12in PCP12in CMP-1in CPEP8in DI12in CMP6in UNK12in CMP 12in UNK12in CPEP-2 in C M P A 8in PCP 6in PCP33in HDPE8in UNK 12in PCP8in PCP6in CLAY6in UNK 12in UNK 10in PCP -1in UNK6in UNK2 4 in P C P6in PC P 8in PCP 8in CPEP8in PCP10in PCP12in PCP10in PCP48in UNK6in CONCin18in CMP-2in CMP8in P C P 8in PCP-1in UNK12in PCP15in PCP 8in PCP12in PCP8in RCP 12in PCP 18in PCP12in PCP6in PCP 12in CLAY 12in PCP 18in PCP12in UNK 1 0 i n P C P 1 8 in P C P 18in HDPE1 2 in UNK 12in PCP 42in PCP12in CPEP1 2 i n U N K 12in UNK 8 in U N K 24in UNK6in P C P 30in UNK8i n PCP8in PVC 30in UNK12in UNK8in UNK 8in CPEP8in CPEP8in PVC8in PVC 12i n UNK12in CPEP 8 i n U N K 12in CPEP12in UNK30in UNK8in C P E P6in PVC12in CPEP 12in PCP12in UNK12in UNK 30in UNK12in U N K 12in U N K 8in DI 12in PVC12in UNK 18in UNK8in P V C 12in UNK4in P C P 12in UNK18in CPEP 8in PVC 12in PVC8in UNK1 2in U N K 8in CPEP8in UNK8in UNK 18in UNK8 in U N K 8in PCP15in PVC 1 2 i n P C P 12in CMP1 8in U N K 42in UNK8in UNK 12in UNK12in UNK 8in UNK12in CSP12in PVC12in CMP 12in UNK18in UNK12in PCPC i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 3SUB-B ASINDELINEATION N o v e m b e r 15 2017 0 400200 Scale in Feet ©Legend "J Outfall ConveyanceBoundary Public Pipe Private Pipe Culvert Project Study Sub-basins Parcels Water Body Building Footprints Parks Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data.8in PCP8in PCP24in PCP24in PCP12in PCP10in CLAY 8in PCP 12in CLAY 12in CLAY24in CPEP24in CPEP 33in HDPE12in PCP 12in PCP 8in PCP24in PCP21in PCP 18in PCP 15in PCP 12in PCP 12in PCP 18in CPEP11in UNK P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 4 Zoning 11x17.mxd 11/15/2017 8:49:47 AM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST "J "J "J "J "J "J "J Cedar River R-14 R-8R-10CDR-14R-14 R-14R-14R-14R-14R-14 R-14 R-14 R-14R-14R-14 R-14 R-14R-14RM-F R-8 R-10CD CDCDCD RM-F CDCA CD CDCDR-14R-14R-14 CDCACD CD CD CDCD CD CDCDCDCDCA CA R-8 CA CD R-8 CDR-8 CD CD R-8 CD CD CD CD CDR-8 CD CD CD CD CD R-10 CA CD CD CD R-10 CA CD R-10 CD R-8 CA CA CD R-10 R-10 CD CA CA R-8 CA R-8 CACA R-8 R-10 R-8R-8CD R-10R-10 CA R-10 CA CACA CA CD R-8 CD R-8 CD R-8R-8 R-8 R-10 R-10 R-8 R-8 R-8R-8 R-8 R-8R-8 CNCN R-8R-8 R-8 R-8R-8 CA R-8R-8R-8 CA R-8 IM R-8 CD CA R-10 CD CD CA CAR-10 R-10 R-10 R-10 R-14RM-F CA RC CA CA CA CA COR CA COR CA CDCDCDCD CD CD CD CD CD CD CD CA R-10 CD CD R-10 R-8 CDR-14 R-14 R-14R-14 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 4ZONING N o v e m b e r 15 2017 0 400200 Scale in Feet © Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Legend "J Outfall Conveyance Boundary Pipe Project Study Sub-basins Parcels Water Body Zoning DesignationRC-Resource Conservation R8-Residential 8 du/ac R10-Residential 10 du/ac R14-Residential 14 du/ac RMF-Residential Multi-Family CN-Commercial Neighborhood Zoning DesignationCA-Commercial UC-Urban Center CD-Center Downtown COR-CommercialOffice/Residential IM-Industrial - Medium P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 5 Model Schematic 11x17.mxd 11/15/2017 9:43:29 AM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Cedar River VeteransMemorial Park Piazza CedarRiver Park Jones Park GatewayPark Tonkin Park BurnettLinear ParkCedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113723 E_113725 E_113741E_113742 E_113745 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114122 E_114123 E_114125 E_114126 E_114385 E_114388 E_114391 E_114393 E_114395E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508 E_134536 E_134539 E_134792 E_134793 E_134799 E_134801 E_134804 E_134805 E_134808 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135876E_135877E_135878 E_135885 E_135886E_135887 E_135888 E_136579 E_136580 E_136582 E_136583 E_136646 E_136802 E_149523 E_149524 E_149525E_149527 E_149554 E_150772E_150773 E_150775 E_150777 E_162430 E_166498 E_166500 E_166501 E_166512 E_166513 E_168879 E_171436 E_171439 E_171440 E_171441 E_171442 E_171443 E_171446 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_188041 E_194449 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222 E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 1021in 12in42in8in12in12in12in72in12in36in 18in 18in12in12in12in24in8in30in12in8in18in18in 12in12in 8in 12in 18in 33in12in24in48in12in 24in 8in 12in 10in 8in12in 8in 6in10in 6in15in 8in12in 6in12in C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 5MODELSCHEMATIC N o v e m b e r 15 2017 0 400200 Scale in Feet ©Legend Input Node !Node Pipe Sub-basins Project Study Area Building Footprints Parks Parcels Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data.8in8in24in 12in 12in 12in 12in P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 6 Existing System Deficiencies 11x17.mxd 11/15/2017 9:45:57 AM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Cedar River Piazza CedarRiver Park Jones Park GatewayPark Tonkin Park BurnettLinear ParkCedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113725 E_113741E_113742 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114122 E_114123 E_114125 E_114126 E_114385 E_114387E_114388 E_114391 E_114393 E_114395E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508 E_134529 E_134536 E_134539 E_134792 E_134793 E_134799E_134801E_134804 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136802 E_149523 E_149524 E_149525 E_149527 E_149554 E_150772E_150773 E_150775 E_150777 E_162430 E_166498 E_166500E_166501 E_166512 E_166513 E_171436 E_171439 E_171440E_171442 E_171443 E_171446 E_178158 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_188041 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 6EXISTING S Y S TEMDEFICIENCIES N o v e m b e r 15 2017 0 400200 Scale in Feet ©Legend !Node Pipe Less than 10 year level ofservice Less than 25 year level ofservice Less than 100 year level ofservice, See Note 1 Sub-basins Project Study Area Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Note 1:Pipes with less than 100-yearservice are already out of compliance for the 25-year storm. P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 6A Existing System Deficiencies 11x17.mxd 12/12/2017 4:00:03 PM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Cedar River Piazza CedarRiver Park Jones Park GatewayPark Tonkin Park BurnettLinear ParkCedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113725 E_113741E_113742 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114122 E_114123 E_114125 E_114126 E_114385 E_114387E_114388 E_114391 E_114393 E_114395E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508 E_134529 E_134536 E_134539 E_134792 E_134793 E_134799E_134801E_134804 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136802 E_149523 E_149524 E_149525 E_149527 E_149554 E_150772E_150773 E_150775 E_150777 E_162430 E_166498 E_166500E_166501 E_166512 E_166513 E_171436 E_171439 E_171440E_171442 E_171443 E_171446 E_178158 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_188041 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U R E 6AEXISTING S Y S TEMDEFICIENCIES D e c e m b e r 12 2017 0 400200 Scale in Feet ©Legend !Node Pipe Less than 10 year level ofservice Less than 25 year level ofservice Less than 100 year level ofservice, See Note 1 Sub-basins Project Study Area Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Note 1:Most pipes with less than 100-yearservice are already out of compliance for the 25-year storm. TailwaterEL = 19.5 P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 7 Alternative 1 Proposed Improvements 11x17.mxd 12/12/2017 2:10:27 PM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Cedar River 36in VeteransMemorial Park Piazza CedarRiver Park Jones Park GatewayPark Tonkin Park BurnettLinear ParkCedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail 18in36in36in 12in 18in24in12in 21in18in18in36in36in 12in 24in 18in 12in18in18in E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113723E_113725 E_113741E_113742E_113745 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114123 E_114125 E_114126 E_114385 E_114387 E_114388 E_114391 E_114393 E_114395 E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508E_134529 E_134539 E_134792 E_134793 E_134799E_134801 E_134804E_134805 E_134814 E_134815 E_134816 E_134817 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136802 E_149523 E_149525E_149527 E_149554 E_150772 E_150773 E_150775 E_150777 E_162430 E_166498 E_166500 E_166501 E_166512 E_166513E_168879 E_171436 E_171439E_171440E_171442 E_171443 E_171446 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_194449 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222 E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 7ALTERNATIVE 1PROPOSEDIMPROVEMENTS D e c e m b e r 12 2017 0 400200 Scale in Feet ©Legend Flooding !No Flooding Upsized Pipe Existing Pipe Sub-basins Project Study Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Disconnect Sub-basinLake-4b & route toRainier Avenue storm drain Shattuck-2 pipe crossesbeneath Lake-8 pipe P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 8 Alternative 2 Proposed Improvements 11x17.mxd 12/12/2017 2:09:16 PM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! !! ! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! ! ! Cedar River VeteransMemorial Park Piazza CedarRiver Park Jones Park Gateway Park Tonkin Park BurnettLinear ParkCedar RiverTrail Extension Liberty Park CedarRiverTrail Cedar RiverTrail Cedar River Trail CedarRiverTrail 36in 12in12in18in18in 36in36in 36in 24in24in12in 24in21in36in18in36in 12in 18in18in18in E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113723E_113725 E_113741E_113742 E_113745 E_113753 E_113758 E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114123 E_114125 E_114126 E_114385 E_114387E_114388 E_114391 E_114393 E_114395 E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508E_134529 E_134539 E_134792 E_134793 E_134799 E_134801 E_134804 E_134805 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136802 E_149523 E_149524 E_149525E_149527 E_149554 E_150772 E_150773 E_150775 E_150777 E_162430 E_166498 E_166500 E_166501 E_166512 E_166513E_168879 E_171436 E_171439E_171440 E_171443 E_171446 E_178158 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_194449 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222 E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 P_Node2325 P_Node2326 P_Node2327 P_Node2328 P_Node2331 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 8ALTERNATIVE 2PROPOSEDIMPROVEMENTS D e c e m b e r 12 2017 0 400200 Scale in Feet ©Legend Flooding !No Flooding Existing Pipe Upsized Pipe New Pipe Disconnected Pipe Sub-basins Project Study Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Disconnect Sub-basinLake-4b & route toRainier Avenue storm drain P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 9 Alternative 3 Proposed Improvements 11x17.mxd 12/12/2017 2:12:56 PM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! ! ! Cedar River VeteransMemorialPark Piazza CedarRiver Park Jones Park GatewayParkTonkin ParkBurnettLinear ParkCedar RiverTrail ExtensionLiberty Park Cedar RiverTrail Cedar River Trail CedarRiver Trail Cedar River TrailCedar River Trail36in 1 8 i n 12in12in 18in36in18in24in12in24in 21in36in18in18in 36in 12in 18in18in18in E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113723E_113725 E_113741E_113742E_113745 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114122 E_114123 E_114125 E_114126 E_114385 E_114387 E_114388 E_114391 E_114393 E_114395 E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508E_134529 E_134536 E_134539 E_134792 E_134793 E_134799E_134801E_134804 E_134805 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136646 E_136802 E_149523 E_149524 E_149525E_149527 E_149554 E_150772 E_150773 E_150775 E_150777 E_162430 E_166498 E_166500 E_166501 E_166512 E_166513E_168879 E_171436 E_171439E_171440E_171442 E_171443 E_171446 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_188041 E_194449 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222 E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 P_Node2325 P_Node2326 P_Node2327 P_Node2328 P_Node2331 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U RE 9ALTERNATIVE 3PROPOSEDIMPROVEMENTS D e c e m b e r 12 2017 0 400200 Scale in Feet ©Legend Flooding !No Flooding Existing Pipe Upsized Pipe New Pipe Disconnected Pipe Sub-basins Project Study Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Disconnect Sub-basinLake-4b & route toRainier Avenue storm drain Shattuck-2 pipe crossesbeneath Lake-8 pipe 24in P:\Mapping\Maps_Generated\Renton\17-10525.00\006\1.1\maps\Fig 10 Preferred Alternative 11x17.mxd 11/29/2017 2:42:21 PM ctolentinoLake-7 Lake-1a Logan-1 Logan2b Logan-3c Lake-2 Lake-3Lake-4aLake-5 Lake-6a Williams-2 Williams-1 Williams-3 Wells Main Old CityHall-2 Shattuck-1 Shattuck-2 Lake-8a Shattuck-3bShattuck-4 Shattuck-5 Lake-4b Lake-1b Lake-6b Logan-2a Logan-2c Logan-3a Logan-3d Logan-3b Old CityHall-1 Lake-8b Shattuck-3a WILLIAMSAVESWELLSAVESS 2ND ST PARKAVENS TOBIN ST MAINAVESBURNETTAVESGARDENAVENHARDI E AV E S WS 3RD ST PLUMTREEPA RK APARTMEN T A C R D S 5TH STLOGANAVESA C C E S S R D SWLANGSTONRD87TH PL SCEDAR RIVER TRAIL B ENS ONRDSSHATTUCKAVESH O U SER W AYSSW SUNSETBLVDFACTORYAVENN 2ND STWILLIAMSAVEN S 4TH ST89THAVES GRANTAVESBRONSONWAYNCEDARAVESHIGHAVESMORRISAVESH A Y E S PL S W WHITWORTHAVESRAI NI ERAVESN 1ST ST PRIVATERDLAKEAVES MAPLEAVESWSW 5TH PLSRIVERSIDEDR N/B I-405 RAMPWELLSAVENS 4 T H P LHARDIEAVENWNW 2ND PL RENTONC E N T E R WA Y S WTAYLORAVENWN BROOKS ST SMITHERSAVESR E N TO N A V E E X TSW VICTORIA ST S 3 R D P L SW 2ND PL S 134TH ST MILLAVESS W 4 T H P L MEADOWAVENBURNETTAVENMAPLEVALLEYHWY B E A C O N W A Y SLINDAVESWCEDARRIVERPA R K DRPELLYAVENN RIVERSIDE DR AIRPORT WAY SW 2ND ST NELSONPLNWNW 2 N D S T S TILLICUM STRAINIER AVENBURNETTPLSSUNSETBLVDNRENTONAVESPE DESTRIAN WALK HOUSERWAYNS/BI-405RAMPI-405FWYWP E R I M E T E R RDLINDAV E NW H O U SER W A YS WELLS AVE SS 3RD STHARDIEAVESW S 2ND STRAINIERAVES S 4TH ST ! ! ! ! ! ! ! ! !! ! !!! ! ! ! !! ! ! ! ! ! !!! ! ! ! ! ! ! ! ! ! !! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!!! !! ! !! ! ! ! ! ! ! ! ! ! !!! !!!! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! !!! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !!! ! ! ! Cedar River VeteransMemorialPark Piazza CedarRiver Park Jones Park GatewayParkTonkin ParkBurnettLinear ParkCedar RiverTrail ExtensionLiberty Park Cedar RiverTrail Cedar River Trail CedarRiver Trail Cedar River TrailCedar River Trail18in 18in12in 12in18in 36in36in 24in24in12in 24in21in36in18in36in 12in 18in18in18in E_112800 E_112957 E_113011 E_113456 E_113458 E_113461 E_113466 E_113468 E_113721 E_113723E_113725 E_113741E_113742E_113745 E_113753 E_113758E_113761 E_113790 E_114020 E_114027 E_114030 E_114032 E_114093 E_114094 E_114097 E_114108 E_114111 E_114113 E_114118 E_114122 E_114123 E_114125 E_114126 E_114385 E_114387 E_114388 E_114391 E_114393 E_114395 E_114396 E_114397 E_114399 E_115261 E_115263 E_115264 E_115265 E_115266 E_115267 E_115290 E_133129 E_133131 E_133171 E_133214 E_133309 E_133310 E_133311 E_133539 E_133944 E_134507 E_134508E_134529 E_134536 E_134539 E_134792 E_134793 E_134799E_134801E_134804 E_134805 E_134814 E_134815 E_134816 E_134818 E_134845 E_134846 E_134847 E_134848 E_134849 E_134850 E_134851 E_135240 E_135876E_135877E_135878 E_135885 E_135886E_135887E_135888 E_136579 E_136580 E_136582 E_136583 E_136646 E_136802 E_149523 E_149524 E_149525 E_149527 E_149554 E_150772 E_150773 E_150775 E_150777 E_162430 E_166498 E_166500 E_166501 E_166512 E_166513E_168879 E_171436 E_171439E_171440E_171442 E_171443 E_171446 E_178159 E_178160 E_178161 E_178165 E_178166 E_178833 E_188037 E_188039 E_188041 E_194449 E_500082 E_500083 E_500084 E_500219 E_502443 E_503438 E_504222 E_504223E_504224 N_1 N_2 O_1 O_2 E_113737 E_134510 E_114131 E_112820 E_112772 E_134782 E_134781 E_136638 E_136639 E_133275 E_112817 E_171437 E_136652 E_114376 E_113736 E_133204 E_115291 O_5 O_3 E_133199 O_4 E_136637 E_145029 E_114377 CB 10 P_Node2325 P_Node2326 P_Node2327 P_Node2328 P_Node2331 C i t y o f R entonDowntown U t i l i t y ImprovementsStormwaterDRAFT F I G U R E 10PREFERREDALTERNATIVE N o v e m b e r 29 2017 0 400200 Scale in Feet ©Legend Flooding !No Flooding Existing Pipe Upsized Pipe New Pipe Disconnected Pipe Sub-basins Project Study Area Building Footprints Parks Water Body Data sources supplied may not reflect current or actual conditions. This mapis a geographic representation based on information available. It does not represent survey data. No warranty is made concerning the accuracy, currency,or completeness of data depicted on this map.BHC Consultants LLC., assumes no responsibility for the validity of anyinformation presented herein, nor any responsibility for the use or misuse of the data. Disconnect Sub-basinLake-4b & route toRainier Avenue storm drain 24inSee Note 1 See Note 1 Note 1:Isolated ponding due to low topography. City to monitorthese locations during rain events to determine if additionalanalysis or improvements are necessary.