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River Islands Development at Lathrop January 2021 <br /> Final River Islands Potable Water Technical Report—Rev 3 #6520 <br /> • Two 8,000 gallons hydro-pneumatic tanks <br /> For the purposes of a steady state analysis,the discharge hydro-pneumatic tanks were not included <br /> in the model. <br /> 4.2.3.3 Proposed Phase II City of Lathrop Potable Water Storage and Booster Pump Station at <br /> River Islands (Phase II BPS) <br /> The Phase II BPS is proposed to be installed along River Islands Parkway in Phase II. As described in <br /> Section 2.6, the total required firm pumping capacity for River Islands is 10,372 GPM. With Phase I BPS <br /> 10,000 GPM firm pumping capacity, the minimum required firm pumping capacity of the proposed Phase II <br /> BPS is 372 GPM. <br /> As discussed in Section 3.3, it is recommended that the Phase 11 PW storage and booster pump station <br /> site be designed to provide a minimum of 4,000 GPM as this will satisfy the firm pumping capacity <br /> requirements, allow for future Phase 11 PW storage, and provide redundant pumping capacity in the <br /> distribution system. As shown in Table 2-8, the proposed installation of three small 2,000 GPM booster <br /> pumps will provide a total system wide firm pumping capacity of 14,000 GPM for River Islands. <br /> The Phase 11 PW Storage and Booster Pump Station site will need to be designed to add an additional 3.5 <br /> MG of storage in order to satisfy the projected Phase I and 11 storage requirements. It is recommended that <br /> two parallel 1.86 MG, 115-feet diameter, welded steel storage tanks be installed to provide the remaining <br /> storage needed for River Islands. The tanks shall be provided with separate inlet and outlet lines with a <br /> maximum height of 30 feet to match the Phase I BPS storage tanks. <br /> 4.2.3.3.1 Hydraulic Model Assumptions—Steady State Analysis <br /> It is recommended that the Phase 11 BPS tanks be designed with a similar combination PSV tank fill line as <br /> Phase I BPS. For Phase II PW storage tanks, the following assumptions were inputted into the model <br /> under the steady state analysis. <br /> • Tank fill combination PSV <br /> For the purposes of the hydraulic model, a 24-inch combination PSV is set to open when the water <br /> level in the Phase II Tank #1 reaches an elevation of 17 feet (4 feet from the FF of the tank) and <br /> close at an elevation of 36 feet. <br /> • 2 x 1.86 MG Phase II BPS Potable Water Storage Tanks <br /> For the purposes of a steady state hydraulic analysis, all Phase 11 tanks are assumed to start full, <br /> with a water level elevation of 36 feet. The site is assumed to be graded to provide a tank FF <br /> elevation of 13 feet. <br /> • Phase II small booster pumps <br /> Two out of the three Phase 11 small booster pumps were modeled to operate as lead pumps using <br /> their VFDs to maintain a distribution pressure of 67.5 psi, similar to Phase I BPS. <br /> • Two 8,000-gallons hydro-pneumatic tanks <br /> For the purposes of a steady state analysis, the proposed discharge hydro-pneumatic tanks were <br /> not included in the model. <br /> 24 <br />