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2021 1,4-DIOXANE PRIVATE WELL TESTING UPDATE IN GEM LAKE AND THE WHITE <br />BEAR AREA <br />July/August 2021 testing <br />In December 2020, the Minnesota Pollution Control Agency (MPCA) directed Water Gremlin to <br />submit a work plan to sample additional private wells within a one -mile radius of the Water Gremlin <br />facility, including those wells with previous detections of 1,4-Dx. Water Gremlin's environmental <br />consultant, Wenck, sent letters to 129 residents requesting access to collect and test a sample of <br />their well water, including some homes just beyond the one -mile radius to include everyone along <br />Goose Lake Rd, where 1,4-Dx was detected in 2020. Wenck received permission to sample the water <br />from 49 wells on 48 properties. <br />MDH staff also collected samples at the same time as Wenck from 15 wells to verifytesting results. <br />These MDH-collected samples were analyzed at the MDH Public Health Laboratory and several of the <br />sample results are still pending. The samples collected by Wenck were tested by Pace Analytical and <br />results were reported directly to MPCA. <br />Sixteen wells are being resampled after a quality assurance/quality control issue was identified, so <br />additional results will be forthcoming. MDH will also be collecting additional samples. Currently, <br />results from 33 wells are available. Of those, 1,4-Dx was detected in 20 private well samples: 8 were <br />above the HRL and 12 were below the HRL. The Public Health Lab reported similar results as the lab <br />used by Water Gremlin. <br />1,4-Dioxane health risks <br />The 1,4-Dx HRL of 1 ppb represents an amount of a contaminant that poses little or no health risk to <br />those drinking the water daily for a lifetime, including sensitive or highly exposed people. 1,4-Dx is <br />considered a likely human carcinogen, based on studies of animals exposed to very high amounts. <br />Concentrations detected in well water in Gem Lake are just above the HRL and present a low health <br />risk. 1,4-Dx breaks down quickly in the body and is eliminated within several days. For more <br />information about 1,4-Dx exposure and health in Gem Lake, see 1,4-Dioxane in Private Wells - Gem <br />Lake and the White Bear Area (PDF) <br />(https://www.health.state.mn.us/communities/environment/hazardous/docs/sites/ramsey/wgprtwe <br />Ilgemlake.pdf). <br />Is the source known for 1,4-dioxane detected in private wells? <br />The distribution of the 1,4-Dx detections in the private wells makes the source unclear. Additional <br />sampling efforts to identify the source are ongoing. Samples of shallow groundwater (less than 100 <br />feet below the ground surface) were collected from borings drilled on the Water Gremlin property as <br />part of monitoring required in December 2019 and the summer of 2020. This monitoring showed 1,4- <br />Dx at concentrations greater than the HRL. <br />In January and February 2020, MDH sampled 11 private wells, detecting 1,4-Dx below the HRL in 3 <br />wells. Water Gremlin sampled 44 more private wells in July 2020, but detected 1,4-Dx in only 3 <br />additional wells, also below the HRL. To better understand the occurrence, movement, and the <br />source of 1,4-Dx in the area, additional data collection and analysis is required. <br />[Note: White Bear Lake city water was tested in March 2020 and no 1,4-Dx was detected.] <br />