2016.04.18 CC Packet - Laserfiche WebLink

Home

6.0 Water Storage 6.1 Storage Requirements Water storage facilities serve several important functions including providing reserve to meet peak demands when well capacity is exceeded, maintaining constant pressure on the system, providing fire flow reserves, and reducing maintenance by preventing frequent pump stopping and starting. Storage facilities are also important during emergency scenarios such as fires, power outages and facility breakdowns. Minimum water storage requirements are outlined in "Ten State Standards." According to this document, "storage volume must be greater than or equal to the average daily consumption, and should include a reasonable fire -fighting reserve." Storage volumes can be decreased if adequate backup generators would allow for wells to be pumped during a power outage. Future water system storage was planned to meet average day demand plus firefighting volumes outlined in Section 3.2 (assumption 10). Again, storage is a place where a joint utility offers efficiency. By combining communities, larger storage structures may become feasible. Larger storage structures are more cost effective from both a construction and operations standpoint. Furthermore, dependent on detailed hydraulic modeling, cities may not have to each individually maintain fire flow reserves which could reduce overall storage volume requirements. 6.2 Water Storage Facilities Figure 6.1 and Table 6.1 depict existing storage volumes and deficits for individual cities and the joint system. The average day demand for the combined six -city region was about 3.5 million gallons over the most recent five yearS2. Combined, the cities would only need to maintain one volume of fire flow, rather than individual fire flow volumes for each city. Incorporating the required fire flow of 1.08 million gallons (the maximum fire flow volume required for the six cities), the minimum recommended storage volume for a Joint Utility (in 2013) is 4.6 million gallons. The available storage capacity of 5.0 million gallons is sufficient to provide the recommended storage volume for a 2013 joint system. An immediate benefit of a Joint Utility is that construction of water storage facilities could possibly be delayed in favor of trunk watermain interconnections. Sizing of the interconnecting watermains would need to be carefully modeled to ensure that adequate fire flow could be conveyed from the storage facilities to the endpoints of the system. 2 Based on DNR Annual Water Use Reports, and City records. Joint Water Utility Feasibility Study 22