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HomeMy WebLinkAboutCC AG PKT 2002-09-09 #J AGENDA REPORT DATE: September 9, 2002 TO: Honorable Mayor and City Council THRU: John B. Bahorski, City Manager FROM: Douglas A. Danes, P.E., Director of Public Works / City Engineer SUBJECT: WEST END PUMP STATION IMPROVEMENT PROJECT, No. 50050 - STATUS REPORT • SUMMARY The proposed City Council action will receive and file the presented information and provide concurrence for the proposed strategy and phasing for the proposed West End Pump Station Improvement Project, No. 50050. BACKGROUND: The West End Pump Station was originally constructed in 1959 as a means to pump storm water run -off from a 150 -acre watershed covering portions of Marina Hill North, Bridgeport and Old Town into the San Gabriel River. The station has two natural gas engines driven propeller pumps each rated at 25,000 gallons per minute. The streets in the adjacent Mobile Home Park drain directly into the wet well of the Pump Station. Consequently, the Park is flooded whenever the water level in the wet well exceeds the street elevation. A fire at the Station during a storm in 2000 completely damaged one of the two natural gas engines leaving the station only at half capacity. The burned engine was replaced by an engine obtained from the County of Orange and reconditioned at the City's expense in October 2001. Other minor improvements were also made to the station at that time. The West End Pump Station does not have capacity adequate for the current standards and it lacks proper controls. In early 2001, the City retained AKM Consulting Engineers to prepare a Preliminary Design Report (PDR) for construction of a new Pump Station to replace the existing. The PDR evaluated the hydrology of the drainage site among other things and found that the existing pumps are not of sufficient capacity to handle the standard 25 -year storm -flow criteria. Actually, according to the PDR, the existing pumps can handle only 71 percent of 5 -year storm flow. Therefore, the PDR recommended replacement of the existing station with a brand new station. The PDR evaluated a number of alternatives for the replacement station. Unfortunately, all of the evaluated alternatives far exceeded the City's budget since they were in the range of $4 to $5 million. One of the other major conflicts in demolishing the existing Agenda Item and constructing the new station in its location is the length of time required for the construction. The poor foundation conditions and complexity of the new station, make it difficult to complete the construction during the April to October time frame. (Due to the essential nature of the pump station for flood control protection, it must remain operational during the rainy season, which is defined as the October to April period). The recommendation from the PDR is to recondition the existing pump station and to construct an additional parallel pump station in the Oakwood Apartments property adjacent to the West End Pump Station. Considering the constraints described above, this alternative is sensible to increase the pumping capacity. The PDR also recommends the construction of a low flow dry weather urban run -off system which pumps low flow waters into the sanitary sewer system. This will improve local water quality and is consistent with the City's Storm Water Master Plan. In addition, the preliminary evaluations of the environmental process including a Coastal Commission Permit and the easement needed at the Oakwood Apartments, may take up to 2 years. This extensive environmental review and documentation is based on the review of documents from other agencies constructing pump stations. Agencies issuing permits on the project include the California Coastal Commission, Army Corp. of Engineers, and LA County Dept. of Public Works. Several local agencies and organizations are also expected to comment on the environmental report. Staff has met with both the Coastal Commission and Oakwood Apartment representatives. Given the circumstances and the budgetary constraints, staff is proposing the following courses of action for immediate implementation during FY 2002/2003: • Construct a new low flow diversion system to pump out dry weather and nuisance flows to the sewer line in First Street. • Recondition and renovate the other natural gas engine obtained from the County and install it at the station, replacing the old engine and associated controls. • Remove, inspect, and replace if necessary the two existing station pumps. • Proceed with the environmental review process of constructing a new parallel pump station. Upon receipt of the environmental permits, the following designs are recommended to be implemented: • Construct an additional wet well in the adjacent Oakwood Apartments parking lot. • Construct two additional electrical motor driven pumps and associated controls on top of the new wet well to bring the total pumping capacity to handle the 25 -year storm flows. FISCAL IMPACT: Funds in the amount of $2,300,000 were budgeted in the City's Capital Improvement Program from the City's Redevelopment Agency. To date the City has expended $150,000 for the engine repairs and station improvements including engineering and the Preliminary Design Report. A low flow division system, and reconditioning of the existing engine and existing pumps is anticipated to cost up to $200,000. The remaining balance will fund the environmental review process, design, construction and inspection of the new pump station. RECOMMENDATION: Receive and file the presented information and provide concurrence for the proposed strategy and phasing for the proposed West End Pump Station Improvement Project, No. 50050. Prepared By: Mark . Vukojevic, .ErP Deputy City Engineer Reviewed By: litiValy Doug Danes, P.E., Director, Public Works Department NO - : ► ' PROV Jo . Bahorski, City Manager •