11-08-1999 Council Packet - Laserfiche WebLink

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capacity of Lift Station No. 2 to 60 gpm. This capacity would result in a flow velocity of approximately 6 feet per second in the 2-inch forcemain, which is acceptable. 6. Lift Station No. 2 pumps into Lift Station No. 1. Lift Station No. 1 also serves a small area north of Highway 15. The design capacity of Lift Station No. 1 is 45 to 60 gpm. Although this capacity has proved adequate, the capacity of Lift Station Nc. 1 will require an increase due to the Lift Station No. 2 upgrade. It is proposed that the capacity of Lift Station No. 1 be increased to at least 80 gpm. Lift Station No. 1 pumps through a short 4-inch forcemain connected to the interceptor forcemain under Highway 15. Ideally, private property Inflow and Infiltration from leaky services or illegal connections should be eliminated. If problems in the Femdale area persist after the proposed improvements, private property Inflow and Infiltration will need to be addressed. The only other alternative would be to install approximately 2,000 feet of larger diameter forcemain, or install deep gravity sewer, under Femdale Road W :st, which would be both difficult and costly. Lift Station Structures A concrete lift station structure would be appropriate for the Highway 12 Bypass Lift Station. Fiberglass or polyethylene lift station structures would be appropriate for Lift Stations 3,4, and 5. A 6-foot diameter concrete structure would be appropriate for Lift Station No. 2. This would allow construction by caisson methods, which may be necessary due to the required depth, soil conditions, high groundwater, and site constraints Electrical Improvements The electrical panels and controls should be replaced due to age and as necessary for larger pumps. Relatively simple controls and alarm systems, such as float switches and external alarm lights are anticipated for all of the lift stations. Construction Sequencing - Femdale Area Construction of the new lift stations would be along side of the existing lift stations. In that manner, the existing lift stations can remain in service until the new lift stations are completed. Septic pumping trucks would be required during the switch-over period. Approvals / Permits Minnesota Pollution Control .\gency (MPCA) permits will be required for all of the lift stations. For the Femdale area lift stations, the Metropolitan Council Environmental Services (MCES) has indicated that they require notification of the Lift Station 1 improvements, since the pumping capacity is to be somewhat increased and Lift Station 1 pumps directly into an MCES forcemain. It is believed that the MCES has given concept approval for the Highway 12 Bypass Lift Station. Formal approval of this lift station will be required by the MCES, since it will be connected directly to an MCES line. K:\iJ9\ U999JO7[w0ntrepcrts\tetUf r€pQrtd0C