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River Islands Development at Lathrop November 2020 <br /> Final Phase 2 Sewer Technical Report Rev 1 #6520 <br /> 7.2.4.1 Sewer Lift Station PS-A2 Preliminary Capacity Analysis <br /> As shown in Figure 2-1, PS-A2 will be located at the end of the River Islands collection system and will be <br /> responsible for pumping all the collected sewage offsite. The station is currently only installed with two <br /> 2,000 GPM pumps with provisions for four additional 2,000 GPM pumps in the future. The two pumps <br /> currently provide a firm pumping capacity of 2,000 GPM in accordance with the City Standards. Table 7-6 <br /> below describes the potential interim, normal, and emergency operating scenarios and the corresponding <br /> pumping capacity requirements for PS-A2. The preliminary capacity analysis is required to be revisited <br /> once final improvement plans and land use summaries are provided for Phase II. <br /> Table 7-6: Sewer Lift Station PS-A2 Preliminary Capacity Analysis <br /> Other <br /> Areas Area Al PWWF <br /> ADWF ADWF (GPD) Minimum Firm Pumping Capacity <br /> Scenario (GPD) (GPD) GPM Requirements <br /> From Collection Area A2 Only 0 568,208 1'278485 61 1 duty+ 1 standby 2,000 GPM pumps required <br /> From Collection Area A2+A1 603,302 568,208 2,422,471 1 duty+ 1 standby 2,000 GPM pumps required <br /> 1,682 <br /> From Collection Area A2+A1+131 1,254,171 568,208 3,738,361 2 duty+ 1 standby 2,000 GPM pumps required <br /> 2,596 <br /> From Collection Area 1,555,498 568,208 4,354,478 2 duty+ 1 standby 2,000 GPM pumps required <br /> A2+A1+B1+C2 3,024 <br /> From Collection Area 1,763,580 568,208 4,780,590 2 duty+ 1 standby 2,000 GPM pumps required <br /> A2+A1+B1+C2+C1 3,320 <br /> From Collection Area 2,446,511 568,208 6,180,211 3 duty+ 1 standby 2,000 GPM pumps required <br /> A2+A1+B1+B2+C2+C1 4,292 <br /> As mentioned previously, PS-A2 is a critical chokepoint in the River Islands sewer collection system. Even <br /> though the City's minimum firm pumping capacity only requires 1 standby pump, due to the size of these <br /> pumps it is recommended to still proceed with the design of 2 standby pumps as there can be an expected <br /> level of difficulty in replacing a damaged pump as the size of the pumps limits the potential of shelf spare <br /> pumps being available from the manufacturer. <br /> 36 <br />