The Minnesota Pollution Control Agency (MPCA) and Minnesota Department of Health are
actively involved in detecting and remediating perfluorochemical contamination of groundwater in
the Twin Cities Metropolitan area. A perfluorochemical plume in the Lake Elmo area of
Washington County contaminated the water supply of more than 285 residents in that area. As a
result, a municipal water system has been connected to more than 200 residents, and domestic
wells in the area were abandoned. This report summarizes the results of a project by the Minnesota
Geological Survey to collect downhole geophysical data from nearly 200 of these domestic wells
before they were sealed as part of the abandonment process. Over 95 percent of these wells extract
water from the lower one-half of the St. Peter Sandstone or upper part of the Shakopee Formation, with the remaining wells open to overlying unconsolidated glacial deposits. The downhole
geophysical data are used to determine rock properties and flow characteristics of these bedrock
aquifers. The results will be used by the MPCA to help better determine the three dimensional
extent of contamination, and in particular provide insight into the role of groundwater flow through fractures. Such information will assist the MPCA in determining appropriate remedial monitoring actions in a cost effective manner.
Runkel, A.C.; Mossler, J.H.; Tipping, R.G..
OFR 07-05, The Lake Elmo Downhole Logging Project: Hydrostratigraphic Characterization of Fractured Bedrock at a Perfluorochemical Contamination Site.
University of Minnesota.
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