The purpose of this chapter is to evaluate the City's water storage capacity. This chapter provides an overview of State rules and regulations pertaining to public water system storage facilities. As part of this evaluation, the sizes and locations of existing storage reservoirs were analyzed to determine if the City has sufficient storage to adequately meet peak demands and to provide recommended emergency and fire flow storage.
Regulations regarding required system storage are found in Section R309-510-8 of the Utah Administrative Code. The first portion of the code outlines the types of storage required:
"(1) General. Each public water system, or storage facility serving connections within a specific area, shall provide:
(a) Equalization storage volume, to satisfy average day demands for water for indoor use and irrigation use,
(b) fire flow storage volume, if the water system is equipped with fire hydrants intended to provide fire suppression water or as required by the local fire code official, and
(c) emergency storage, if deemed appropriate by the water supplier or the Director."
The following sections discuss how each of these types of storage are addressed within the City's water system.
Sources, major conveyance pipelines, and pump stations are usually sized to convey peak day demands. During peak hour demands, storage must be used to meet the increased demands. Equalization or operational storage is the storage required to cover the difference between the maximum rate of supply and the rate of demand during peak conditions.
For several decades, equalization storage requirements per the State of Utah were a uniform 400 gallons per ERC for indoor water use plus outdoor water use based on location and irrigated area per ERC. For West Jordan, the total required storage was calculated as 821 gallons/ERC in the City's 2016 master plan. State storage requirements have changed significantly since that time.
In 2018, the Utah State Legislature passed an updated Utah Code 19-4-14, which supersedes most of the previous statewide requirements by directing the Division of Drinking Water to establish system- specific source and storage sizing requirements for public water systems. These standards are typically based on the last 3 years of water use data that the City has reported to DWRi. The City received a letter from the Division of Drinking Water dated June 18, 2020, which establishes the storage requirements for their system. The standards set in this letter are based on the City's water use data for 2016 through 2018.
For this analysis, the equalization storage requirement will be based on the system-specific minimum storage requirements as provided by the Division of Drinking Water, which is 650 gallons per ERC. This is obviously a significant reduction from the standard used in the past and will result in different storage needs than have been identified in past master plans.
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