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<br />City of Gem Lake Comprehensive Plan GEMLK 140643 <br />Page 79 <br />8.3 Future Water Supply Needs <br />Since Gem Lake does not intend on having their own water supply source, the City must <br />rely on the surrounding communities to maintain a safe and reliable source, however, <br />delivery of the water once purchased is the responsibility of Gem Lake. A cities <br />distribution system must be capable of meeting the daily water demands of the users. <br />Water demands of a city are based off land use patterns, projected populations, and per <br />capita water usage patterns. Historical customer water use data is unavailable for the <br />City of Gem Lake, so the water demand analysis was based off of land use patterns. For <br />each of the three service areas an average day demand and maximum day demand was <br />determined. When determining the demands it was assumed that the average day <br />demand was 250 gallons/day/residence, and the maximum day demand peaking factor <br />was 2.6 as given by the Metropolitan Council. <br />The total demands for the City of Gem Lake are an average day demand of 97,00 gallons <br />per day (gpd) and a maximum day demand of 176 gallons per minute (gpm). <br />Vadnais Heights service area has an estimated average day demand of 22,000 gpd and <br />an estimated maximum day demand of 40 gpm. <br />White Bear Lake service area has an estimated average day demand of 33,250 gpd and <br />a maximum day demand of 60 gpm. <br />White Bear Township service area has an estimated average day demand of 16,000 gpd <br />and a maximum day demand of 29 gpm. <br />8.4 System Pipe Sizing <br />In addition to meeting daily water demands, a distribution system must be capable of <br />meeting the fire flow requirements. Available fire flow is the system’s ability to provide <br />sufficient flow in the event of a fire while maintaining a minimum system pressure of 20 <br />psi. The amount of fire flow needed depends on the property and land use of that area. <br />Fire flow available to Gem Lake will be supported by each connection to each individual <br />water system. In general, close proximity to the connecting systems water tower and <br />large diameter trunk water mains will enable more robust fire flow availability. <br />Pipe sizes in a distribution system are determined based on daily flow demands or fire <br />flow requirements. In smaller communities the fire flow requirements tend to be larger <br />than the daily flow demands. The total daily demands for the City of Gem Lake are lower <br />than the fire flow demands, therefore the fire flow demands will dictate the pipe size. Pipe <br />sizes for the City of Gem Lake distribution system were modeled as part of a Metropolitan <br />Council Regional Project. The pipe sizes determined for that project will be used for the <br />City distribution system. The determined pipe sizes are 10, 8, and 6 inch pipes for <br />Vadnais Heights service area, 12, 8, and 6 inch pipes for White Bear Lake service area, <br />and 10 and 8 inch pipes for White Bear Township. The Attached map below documents a <br />suggested pipe size layout for the City of Gem Lake. <br />8.5 Interim Water System <br />There are some steps that the City should undertake if it continues to primarily rely on <br />private wells for its water supply. For instance, a program should be set up to require <br />periodic testing of water from every well in the City to determine water quality. This <br />program could include steps to take in the event water quality fails to meet minimum <br />standards.