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

Upper Pond: This Pond was intended to have an overflow elevation of 486.7, however grading along the southern retaining wall of the Pond was installed incorrectly with a maximum elevation of 466.7. This resulted in runoff exiting the pond along the retaining wall and flowing down 100" Street, back into the lower pond system. In April 2020, a berm was constructed in the upper pond to prevent this overflow which increased the overall upper pond volume by approximately 39,624 CF. See the calculation below: UPPER POND ORIGINAL MAX W.S. SQUARE FOOTAGE 19649 NEW MAX W.S. SQUARE FOOTAGE 19975 ELEVATION DIFFERENCE 2 UPPER POND VOL. INCREASE 39624 CF 3. RESULTS AND ANALYSIS The results of the corrective actions are a net increase in treatment pond volume of 32,276 CF. Based on the original drainage report for the site prepared by Barghausen Consulting Engineers in 1998, the intent of the two ponds Is to provide water quality and detention volumes prior to releasing runoff to the existing wetland north of the W info site. The ponds were designed in series, therefore the reduction of volume of the lower Pond but a net increase of volume should not impact the overall function of the system. 9 City of Everett Permit Review EVER_E_TT Status: Reviewed for Permit 01/19/2023 6.54:31 PM