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Feasibility Study Update Gem Lake Municipal Water Supply Prepared for City of Gem Lake, Minnesota Background A previous municipal water supply feasibility study was developed by SEH to evaluate alternatives for supplying potable water to Gem Lake residents and businesses and was provided to the City on September 8, 2006. The scenarios explored in the 2006 Municipal Water Supply Feasibility Study included the potential for constructing an independent water system for Gem Lake as well as a centralized water distribution system within Gem Lake with source water provided by interconnections to one of the neighboring communities of White Bear Lake, White Bear Township, or Vadnais Heights. Based on evaluation of estimated costs, constructability, water quality, and hydraulic function, SEH concluded that connection to any of the neighboring water distribution systems was possible from a constructability point of view, however the costs and system performance varied for the different interconnection scenarios. Since the development of the 2006 study, Gem Lake has constructed an interconnection with the City of Vadnais Heights that serves the Villas of Gem Lake residents and an interconnection with the City of White Bear Lake that serves the commercial district. The majority of residents remain on private wells. Recently the Minnesota Pollution Control Agency (MPCA) and Minnesota Department of Health (MDH) completed sampling for 1,4- dioxane, a likely human carcinogen, in private wells in Gem Lake and the White Bear area. Results of the sampling showed levels above the MDH health -based guidance value for 1,4-dioxane in some of the private wells in Gem Lake and are shown in MDH's fact sheet in Appendix A. Due to the high levels of 1,4-dioxane in some of the wells, the City is again :ploring the feasibility of a municipal water supply system to supply safe and reliable nkina water to its residents and businesses. 2 Gem Lake Water Needs A feasible water supply for the City must be both safe and reliable. A safe water supply is one that meets and/or exceeds all State and Federal regulations. Additionally, in light of 1,4-dioxane which is not a regulated contaminant, the water supply should meet all MDH health -based rules and guidance. A reliable water supply is one that meets the City's water demand and required fire flow availability. Per discussions with the City, this updated feasibility study will focus on the feasibility of a centralized water distribution system within Gem Lake with water supplied solely from either the City of White Bear Lake or White Bear Township's community water systems. To determine the adequacy of each water system's ability to supply the City of Gem Lake, we first estimated the projected ultimate water demand from Gem Lake residents and City of Gem Lake, MN Page i