CCP 02-09-1998 - Laserfiche WebLink

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I I. INTRODUCTIONIEXISTING CONDITIONS I On December 8, 1997, the Arden Hills City Council ordered the preparation of a feasibility study I for the possible elimination of sanitary sewer Lift Station #11. The purpose of the feasibility study is to examine the costs and benefits of eliminating the lift station, the feasibility of the proposed construction, and the estimated costs and method of financing for the improvements. I The City currently maintains 13 sanitary sewer lift stations. These sanitary sewer lift stations are needed to pump sewage from the low point in one City sewer network to a higher sewer main I located in a nearby network. Sewage flows may pass through several lift stations in the City and neighboring cities before finally arriving at the Metro Plant in St. Paul for treatment and discharge into the Mississippi River. I Lift Station # 11 is located near the intersection of Prior A venue and Highway 96 adjacent to the Arden Manor Mobile Home Park. The station currently handles sewage generated from the I mobile home park, businesses and homes along the west side of Highway 10, the commercial and industrial properties located in the Gateway Business District including Phase I of the Welsh development. One single family home located along Lake Shore Place also is served by Lift I Station # 11. Sewage effluent from the station is pumped to an existing gravity sewer main located in Lake Shore Place via a four inch force main. This sewer main runs south along old ,- Highway 10 then west across the southem end of Round Lake and into the 21 inch sewer in 14th street. The City maintains three basic types oflift station designs/configurations. Lift Station # 11 is I referred to as a "can type" station. This type of lift station generally consists of a wet well manhole, two electrically operated pumps, electrical controls, valves located in a manhole or I underground in a dry well manhole. Lift Station #11 was constructed in 1970 and consists of a steel tube dry well adjacent to a 6 foot diameter concrete wet well. The station depth below grade is approximately 24 feet. The dry well houses two Chicago brand pumps as well as valves I and controls for the pumps. The station is in relatively good condition however some corrosion spots have been noted on the sides and floor of the dry well. I Due to the inherent nature of mechanical systems to break down, lift stations require daily maintenance checks and frequent routine maintenance to keep operating efficiently. If a mechanical problem does occur at a station, City staff must respond immediately, diagnose the I problem and make repairs quickly. Private property damage can occur very soon after a lift station stops operating by causing sewage backups into basements or lower levels of homes and businesses. I The design of the existing station creates some maintenance and safety concerns for City staff. The steel tube dry well is difficult to access and requires maintenance personnel to enter it in I order to check the basic operation of the station. Since the dry well is located at the same depth .- I I