Loading...
HomeMy WebLinkAboutEx_14_Development_Engineering_Advisory_Comments DEPARTMENT OF COMMUNITY & ECONOMIC DEVELOPMENT M E M O R A N D U M DATE: March 13, 2024 TO: Alex Morganroth, Senior Planner FROM: Sam Morman, Civil Engineer II SUBJECT: SE 172nd St Water Quality Retrofit Project LUA24-000064 I have reviewed the application for SE 172nd St Water Quality Retrofit Project located in portions of the ROW on SE 172nd St, 122nd Ave SE, 123rd Ave SE, 124th Ave SE, and 125th Ave SE and have the following comments. EXISTING CONDITIONS The site is comprised of ROW on SE 172nd St, 122nd Ave SE, 123rd Ave SE, 124th Ave SE, and 125th Ave SE. WATER: The proposed development is within the Soos Creek Water and Sewer District. SEWER: The proposed development is within the Soos Creek Water and Sewer District. STORM: There is a 12-inch surface water main in SE 172nd St that runs west to east. 122nd, 123rd, and 124th Ave SE have catch basins collecting road runoff that is conveyed through 18-inch surface water mains to the east and ties into an 18-inch surface water main running north to south within 125th Ave SE. STREETS: The site is comprised of ROW on SE 172nd St, 122nd Ave SE, 123rd Ave SE, 124th Ave SE, and 125th Ave SE. SE 172nd and 125th Ave SE have an existing ROW width of 60-feet. 122nd, 123rd, and 124th Ave SE have an existing ROW width of 50-feet. WATER COMMENTS 1. Water service is provided by Soos Creek Water and Sewer District. 2. Review of any water plans will be conducted by Soos Creek Water and Sewer District and the Renton Regional Fire Authority. 3. If the scope impacts water, plans approved by Soos Creek Water and Sewer District shall be routed to the City for final review prior to permit issuance. SEWER COMMENTS 1. Sewer service is provided by Soos Creek Water and Sewer District. 2. Review of the sewer plans will be conducted by Soos Creek Water and Sewer District. DocuSign Envelope ID: 01C814B1-0BBA-4C1D-A80D-C3E897DA2B57 SE 172nd St Water Quality Retrofit Project– LUA24-000064 March 13, 2024 Page 2 of 3 3. If the scope impacts sewer, plans approved by Soos Creek Water and Sewer District shall be routed to the City for final review prior to permit issuance. SURFACE WATER COMMENTS 1. A geotechnical report dated March 23, 2020, completed by Associated Earth Sciences Incorporated, was provided with the Land Use Application. The report discusses the soil and groundwater characteristics of the site and provides recommendations for project design and construction. Geotechnical recommendations presented in this report do not support the use of infiltration. 2. Osborn Consulting, Inc., with the Land Use Application, submitted a Preliminary Drainage Plan and Technical Information Report (TIR), dated July 21, 2021. Based on the City of Renton’s flow control map, the site falls within the Flow Control Duration Standard- Matching Forested and is within the Soos Creek Drainage Basin. The report is based on a full drainage review and Core Requirements 1 thru 9 have been discussed in the Technical Information Report. i. Update all references to the 2017 RSWDM to be referring to the 2022 RSWDM. a. Offsite Analysis, RSWDM Core Requirement #2: All proposed projects must submit an offsite analysis report that assesses potential offsite drainage and water quality impacts associated with development of the project site. a. The TIR will need to provide a Level 1 Downstream Analysis will be required prior to issuance of a civil construction permit. b. Flow Control, RSWDM Core Requirement #3: Any proposed detention and/or water quality vault shall be designed in accordance with the RSWDM that is current at the time of civil construction permit application. The TIR has indicated that detention is not needed. c. Conveyance, RSWDM Core Requirement #4: All new conveyance systems constructed as part of the project must be sized to RSWDM standards for the total tributary area (onsite and offsite) that the storm systems serve. The proposal addresses this through conveyance capacity calculations. d. Construction Stormwater Pollution Prevention, Core Requirement #5 ii. A CSWPP shall be provided with the TIR and submit prior to civil construction permit issuance. e. Maintenance and Operations, Core Requirement #6 i. A maintenance and operation manual shall be provided with the TIR and submit prior to civil construction permit issuance. f. Water Quality, RSWDM Core Requirement #8: All projects that add more than 5,000 square feet of pollution generating impervious surface (PGIS) that is not fully dispersed and less than 0.75 acre of pollution generating pervious surface that is not fully dispersed require water quality. The TIR indicates that the total new PGIS is under 5,000 SF so the project is exempt from City water quality requirements. g. Onsite BMPs, RSWDM Core Requirement #9: Appropriate on-site BMPs will be required to help mitigate the new runoff created by this development. The proposal discusses the feasibility of BMPs. 3. Storm drainage improvements along all public street frontages are required to conform to the City’s street and stormwater conveyance standards. Any new storm drain installed on or off-site shall be designed and sized in accordance with standards found in Chapter DocuSign Envelope ID: 01C814B1-0BBA-4C1D-A80D-C3E897DA2B57 SE 172nd St Water Quality Retrofit Project– LUA24-000064 March 13, 2024 Page 3 of 3 4 of the 2022 RSWDM and shall account for the total upstream tributary area, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. 4. A Construction Stormwater General Permit from the Washington Department of Ecology is required as the proposed clearing will disturb more than one acre. TRANSPORTATION COMMENTS 1. Refer to City code 4-4-080 regarding driveway regulations: a. Driveways shall be designed in accordance with City standard plans 104.1 and 104.2. b. Maximum driveway slope is 15%. Driveways which exceed 8% shall provide slotted drains at the lower end with positive drainage discharge to restrict runoff from entering the garage. c. The maximum width of a single loaded garage driveway is 9-feet and the maximum width of a double loaded garage driveway is 16-feet. If a garage is not present, the maximum driveway width is 16-feet. i. Driveways as depicted are acceptable. d. Driveways shall not be closer than 5-feet to any property line. i. Driveways as depicted are acceptable. 2. Paving and trench restoration shall comply with the City’s Trench Restoration and Overlay Requirements. DocuSign Envelope ID: 01C814B1-0BBA-4C1D-A80D-C3E897DA2B57