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JSACIVIL <br />Engineering l Planning l Management <br />Bypass System: The original system was designed with a gravity bypass at both pump stations which was <br />intended to allow the runoff entering the pump station to bypass both the upper and lower ponds in the <br />event of a pump failure or the pumps hitting rapacity. <br />A full description of the original system can be found here: 1999 Drainage Report. <br />Unfortunately, as is described in Section 4 of this memorandum, many of the proposed components of this <br />stormwater system were not installed correctly, which has led to ongoing Hooding issues. <br />3. <br />Beginning in 2016, Wini has taken significant steps to identify the cause and mitigate the ongoing flooding. A <br />chronological list of key events, actions taken, etc. is below: <br />a) Jan 2016: Wini completes significant maintenance and restoration on their ponds. <br />b) March 2016: Wini engages SO Alliance to complete a review of the stormwater system. <br />c) March 2020: Terraria Surveyi ng completes a survey of the stormwater system to assist with assessment. <br />o A link to the survey can be found here: 202110310 Survey <br />d) April 2020: Modifications to the upper and lower pond were completed. See Section 4. <br />e) Sep 2021: An onsite meeting with Aqualis,City, and JSA staff to review the Hooding and discuss proposed <br />solutions was held. <br />f) Sep 2021: Wini engages Aqualis to complete additional surveys and a CCTV of flooded stormwater <br />lines. <br />g) Nov 2021: CM Completed. <br />o A link to the CCTV Documents can be found here: Nov 2021 CM Inspections <br />h) Dec 2021: Wini engages JSA to review the CCTV data as well as the historic design documents and <br />prepare a stormwater model of the existing system (as surveyed) to identify potential causes and <br />solutions. <br />I Jan 2022: JSA Provides City with results of the model and findings. <br />o A link to the email and documents provided to the City can be found here: 2022-0105 Email <br />j) Ian 2022:JSA & City staff meet to discuss findings. <br />k) Ian 2022: Preparation of this Memorandum <br />4. <br />Following the completion of the survey by Terraria in March 2020, It was determined the overflow of the lower <br />pond was installed 0.15' above the rim of the lowest CB in 16v Avenue. The 1999 design cal led for the overflow <br />20220125 1 2M4 <br />