Agenda - Council - 01/11/2022 - Laserfiche WebLink

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Page 2 5B), and • The Hunt Addition and all of the Makowsky Addition develop simultaneously (Figure 5C). In relation to proposed infrastructure improvements, it appears that the trunk facility extensions will be similar whether part or all of the Makowsky property develops. V. TRUNK & LATERAL SANITARY SEWER SYSTEM The primary area of analysis is depicted in the City's Comprehensive Sanitary Sewer Plan as District R22 (see Figure 2). Based on the City's Sanitary Sewer Comprehensive Plan, the area will be served by the 21-inch main line located south of Trott Brook in the Variolite Street right of way. The Comprehensive Plan depicts the flows being directed to an existing lift station located in the Brookfield Estates Addition, along 168th Circle, just west of Olivine Street. Lift Station Considerations The City has indicated that alternative means of conveyance to the Variolite system should be analyzed, as the existing lift station appears to be at or near capacity. A review of the Comprehensive Plan indicates the lift station was initially sized for a portion of the sewer district, with upgrades required in the future if larger areas were to be serviced. Pumping data received from the City for June of 2021 indicates the existing duplex pumping station experiences an average of 44 starts per day, with the average run time being 2.59 minutes per start. Based on the pumping data, the lift station has adequate capacity to accommodate flows from undeveloped properties located east of Nowthen Boulevard, along with flows from the new developments. Rather than upgrade the lift station to serve the entire area north of Trott Brook, the City indicated their preference is to construct a new lift station on the north side of Trott Brook. The new lift station would serve the area located north of Trott Brook as shown in green on Figure 2. There are several reasons to consider construction of a new lift station rather than continuing to add flows to the existing facility: • The depth of the existing lift station makes it difficult to maintain with the City's equipment. The City has expressed concern with adding more flow to the station, which may result in more frequent maintenance of the facility. • Installation of a new lift station limits the number of impacted properties if the existing facility failed due to flooding, lighting strikes, etc. For these reasons, we have assumed new developments would be directed away from the existing lift station to the extent practical. Hunt Addition Only Sanitary sewer service for the Hunt Addition was analyzed based on the proposed concept plan for the site. When fully developed, the flows from the site will be approximately 18,000 GPD average daily flow and approximately 67,000 GPD peak flow. The flow will ultimately be connected to a gravity system that is proposed to traverse the Makowsky property. An interim system will be required until such time as the Makowsky property develops. The interim service is anticipated to be routed to the same manhole that serves the new Prepared by: Bolton & Menk, Inc. Trott Brook North Infrastructure Study — City of Ramsey