C153701 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I Section 3 - Development of Alternatives Treated Water Storage Assumption: The treated water storage should consist of operational storage, emergency storage, and fire storage. Typical industry values for these items are as follows. The operational storage, which covers the difference between peak-day and max-hour flows, should be sized at 25% of max-day flow or 1.75 MG. The emergency storage, which covers periods when the pipeline is not carrying water due to planned or unplanned outage, should be equal to a one average-day, or 2.4 MG. The fire storage, which provides extra water during fires, should be sized for 2,500 gpm for two hours, or 0.3 MG. The sum of these three types of storage is 4.45 MG. This value is similar to the Rural Economic and Community Development (RECD) criteria that treated water storage be equal to no more than two times the average-day flow, or 4.8 MG. Options: A treated water elevated storage tank should be located in the City for all alternatives considered. This elevated tank would serve to equalize the pressures in the City, as well as maintain minimum pressure during high-use periods. The proposed minimum size of the storage tank is 0.3 MG and the proposed height is 130 feet to maintain 60 psi. Final values would be determined in the preliminary design stage. Previous reports suggested that the City use pumped groundwater to provide for fire and emergency storage in order to save money by decreasing the amount of treated water storage. This concept has several disadvantages. First, it requires that the existing well system be kept maintained and ready for use on a short notice, representing a considerable expense. Second, pumping poor quality groundwater into the system may potentially result in a customer receiving water that does not meet acceptable standards. Use of the wells as an emergency supply will effect the quality of the water in the distribution system, and result in more requirements for testing the water. For these reasons, we recommend against the use of groundwater for emergency storage. We do, however, recommend that the use of groundwater be pursued for non-potable uses such as irrigation of parks, cemeteries, and school grounds. Water Treatment Plant Assumptions: The water treatment plant will be sized to meet the max-day demand in 2020 of 7.0 MGD, and should have two identical process trains so that plant operation can continue during maintenance. MONTGOMERY WATSON Page 3-6