9900 19TH AVE SE WINCO FOODS 2025-03-27

JSACIVIL Engineering I Planning I Management Technical Memorandum To: City of Everett From: Brandon Johnson, PE—JSA Civil, LLC Date: September 12, 2022 ■ City of EvereU Permit Review EVER_E_TT StMUS: Reviewed for Permit 01/19/2023 6:54:26 PM Subject: Pond Volume Adjustments Project: Wince Foods Store No. 104 (Everett, WA) 1. INTRODUCTION: This memorandum has been prepared by 1SA Civil USA) at the request of Wirco Foods (WinCo) and the City of Everett (City) to document pond volume adjustments as a result of actions taken by Wince to resolve the ongoing Flooding issues at the intersection of 100'" St SE and 16P Ave SE. 2. BACKGROUND: Since 2016, Wince foods has taken significant steps to reduce ongoing Flooding. These steps are documented in the January 2022 Technical Memorandum prepared by JSA Civil, which has been previously submitted to the City of Everett. Two of the items listed as corrections Impacted the volumes of the detention ponds south of Wince, known as the lower and upper ponds. A detailed description of the corrective actions taken in each pond and the corresponding pond volume adjustments are documented below: • Lower Pond: The overflow standpipe in the lower pond was installed 2" above the rims of the adjacent CB's in 16T' Avenue, contributing to the 16r" Avenue roadway Flooding. In April 2020, the overflow standpipe was lowered by 6" which reduced the overall lower Pond volume by approximately 7,348 CF. See the calculation below: LOWER POND ORIGINAL MAX. W.S. SQUAT E FOOTAGE 15128 NEW MAX W.S. SQUARE FOOTAGE 14265 ELEVATION DIFFERENCE(FT) -0.5 LOWER POND VOL. REDUCTION 7348.25 CF