Agenda - Public Works Committee - 09/17/2019

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3.0Inventory of Potential Contaminant Sources In Part 1 of this WHPP amendment, WHPAs for the Ramsey water supply wells and the associated DWSMAs were delineated. The DWSMAs encompass the 10-year groundwater time of travel WHPAs (MDH, 2018). As discussed above in Section 1.3, two DWSMAs were delineated for As shown on Figure 2 and in Appendix C, the current land use (i.e., year 2016 data from the Metropolitan Council) data indicates that numerous land uses are found within the DWSMAs. Land uses in the DWSMAs that cover more than one percent or more of the area in the DWSMAs include Residential of various types, Undeveloped land, Park/Recreational/Preserve, Retail and Other Commercial, Agricultural, Major Highways, and Open Water. Per the April 4, 2019 Scoping 2 Decision Notice, the City performed a Potential Contaminant Source Inventory (PCSI) within the DWSMAs. 3.1Inventory Process At Scoping Meeting No. 2, the types of potential contaminant sources that must be inventoried in the Ramsey DWSMAs Area were identified. As discussed in Appendix C, sources of data accessed for the potential contaminant source inventory include Minnesota Department of Health (MDH), Minnesota Department of Natural Resources (MDNR), Minnesota Department of Public Safety (DPS), Minnesota Geological Survey (MGS), Minnesota Office of Pipeline Safety (MnOPS), Minnesota Pollution Control Agency (MPCA), Metropolitan Council, Minnesota Geospatial Information Office (MGIO), Minnesota Department of Transportation (MnDOT), and U.S. Environmental Protection Agency (USEPA) databases. Aquifer vulnerability in the Ramsey DWSMAs is classified as Moderate (Figure 1). The potential contaminant source types that must be inventoried vary based on the aquifer vulnerability classification. In areas where the aquifer vulnerability is classified as Moderate the types of potential contaminant point sources inventoried include above-ground and underground storage tanks, leaking underground storage tank (LUST) locations, potential Class V well locations (Class V wells are wells or other structures that facilitate injection of wastes into the subsurface), pipeline facilities, chemical storage locations, spills/potential contamination sites, and wells. The first step in the inventory was to determine if there were any potential contaminant sources in the Inner Wellhead Management Zone (IWMZ) or the Emergency Response Zone (ERZ) around each of the Ramsey wells. The IWMZ is defined as the area within a 200-foot radius of each municipal well. The most recent IWMZ inventory for each of the Ramsey municipal wells is presented in Appendix C. The ERZ is defined as the area within which the travel time of groundwater to a municipal well is one year or less. The inventory was then expanded out to the boundaries of the DWSMAs. 8 8