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I~ II- Bkf place and factory built stations) and submersible stations (cast-in-place and pre-cast). Other alternatives that the consultant believes to be feasible and cost-effective for the site and situation should also be included With the proposed short-term improvement to the existing pump station, and having discussions with City staff and understanding City's needs, and with our extensive pump station design experience, BKF will begin to develop the new pump station alternatives. The following major items need to be discussed or agreed upon between BKF and the City during the development of the different alternati ves: . · It is our understanding that the existing pump station has a peak capacity of 3.S9 mgd, and as stated in the Wastewater Master Plan dated March 2006 that this pump station is in need of an upgrade from 3.S9 mgd to 11.9 mgd. This is three times more than the existing pump station capacity. BKF will review the available data and evaluate the pump station design capacity and to reach a consensus with the City on future pump station design need. The capacity of the pump station will dictate the building size, control panel, cost, and number of pumps. If the capacity of the future pump station is about three times larger than the existing pump station, the horse-power of each pump will become an issue. Idling a very large horse power pump for firm capacity maybe an expensive option and should be further investigated. The number of pumps will be studied and cost analysis will be discussed. · Various types of building enclosure including pre-fabricated metal building, timber building, and concrete block building are possible alternatives. Thc type of finish and roofing material also need to be discussed for cost estimate purpose. 1 . The existing pump station consists of a wet well which receives sewer from a 24" main from the east and 33" main from the south, and a dry pit housing all the three pumps and motors in a very deep and extremely confined space. It is difficult for the maintenance crew to get in and out for maintaining the equipment. Submersible pump stations are very popular and economical. The pumps and motors can be lifted to above ground for easy maintenance in the shop or in the factory. A pre-cast wet well and cast-in-place concrete wet well structure will be studied and cost analysis will be performed. ,J . Each of the existing dry pit pumps have an above-ground discharge pipe with control valve and swing check valve, and discharges to the Dublin-San Ramon Services District (DSRSDj Wastewater Treatment Plant (WWTP) through a 2,700'- 16" force main and a 24"gravity system. This information will be used to determine the pumping head of the existing and future pump station. The existing discharge system is also a factor used to determine the pump size, the number of pumps, and dimension of the wet well and building for the alternative study. The existing pump station with above ground discharge piping and valve system has a good chance to allow air entrap in the force main system, therefore underground piping and valve system should be coosidered. It is also aesthetically more attractive than the above ground piping system. . The Wastewater Master Plan dated March 2006 reeommended replacing the existing 16" force main with an IS" force main. The area of an IS" force main is only about 26ck more than the 16" force main. However, the master plan also indicated that the capacity needs to increase from 3.89 mgd to about 11.9 mgd. Pumping head will be significantly increased if an IS" pipe is to replace the existing 16" force main, but we suspect that one IS" FM ma)' not meet the capacity of 11.9 4