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HomeMy WebLinkAboutC_Response_Letter_230320_v1 CORPORATE OFFICE (253) 984-2900 beylerconsulting.com 5920 100th St. SW, Suite 25 Lakewood, WA 98499 ENGINEERING + SURVEYING LAND SURVEYING | CIVIL ENGINEERING | STRUCTURAL ENGINEERING | PLANNING & FEASIBILITY STUDIES PROJECT MANAGEMENT | PERMITTING SERVICES | CONSTRUCTION MANAGEMENT March 20, 2023 Andrew Van Gordon Associate Planner 1055 S Grady Way Renton, WA 98057 RE: 18.00392, Castro Short Plat, LUA22-000053 King County Parcel No. 0739000085 Mr. Van Gordon, The purpose of this letter is to address the review comments dated December 20th 2022 for the proposed Castro Short Plat. To expedite your review and approval of the subject plans, below are our responses in bold, with your comments included herein for reference: Civil Engineering, Nathan Janders 1. In the TIR a flow control facility exemption is claimed per section 1.2.3.1.B of the RSWDM due to an increase of less than 0.15 CFS. However the modeling used to support the exemption did not model the target areas, for which permeable pavement and limited infiltration BMPs are proposed, in accordance with table 1.2.9.A of RSWDM. The table indicated how to model the developed condition for which a BMP is applied to target surface (such as 50% impervious and 50% grass for permeable pavement) ,however the modeling needs to be revised to demonstrate compliance with section 1.2.9.A. • Note, if a detention facility is determined to be required than a type 4 downstream drainage problem shall be evaluated in the downstream analysis. Response: Site is implementing a detention vault to capture all stormwater runoff from impervious surfaces. This vault will have a controlled release through a riser structure, which will achieve the flow control standard. The downstream analysis in the Drainage report addresses a possible type 4 downstream drainage problem. 2. The applicant should verify with geotechnical engineer the stability of fill soils when saturated (see section C.2.7 permeable pavement infeasibility criteria list no. 7) Response: Project is no longer proposing permeable surfaces. Verification of stability of fill soils is no longer required. 18.00392 l Castro City of Renton Response Letter l 03.09.2023 Page 2 of 2 If you have any questions or need additional information, please feel free to contact me at (253) 984-2900 or cwashington@beylerconsulting.com. Respectfully, Camille Washington Beyler Consulting, LLC