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WATER GREMLIN PUB-LIC HEALTH ASSESSMENT: PUBLIC COMMENT DRAFT directions may varyfrom the regional groundwaterflow direction, There. is little information regarding local grou ndwater flow directions in the area (if .the Water Gremlin property. Monitoring wells. in the. buried sand aquifer are needed to deterrnine the local flow direction in this important aquifer. Flow direction 1n the very shallow groundwater (less than 30 feet) is likely to be influenced by topography, nearby su rface waters, and precipitation. For example;. near Lambert Creek, the shallow groundwater may discharge into the creek part of the year and at other times surface water from the creek may flow outward into the: shallow glacial deposits. Since June 2019, there have been five phases of groundwater investigations on and near the Water Gremlin property: These have generally started at areas of known or suspected releases of site -related contaminants and expanded outward to define the horizontal and vertical extent:of the contamination and to evaluate potential releases to nearby surface waters. Investigations in 2019 and 2020 focused on shallow groundwater with borings 50.feet.below the groundsurface or less, although six borings were drilled deeper (70-100 feet deep) to sample water in the buried sand aquifer. In 2021, additional borings were drilled on and.;offthe Water Gremlin property to. evaluate the water quality in the. buried sand aquifer. The results of the first four investigations are described in detail in the site reports (Wenck, 2019b, 20201 2021) and summarized here. MPGA provided the analytical results of the 2021 investigation to MDH, but a site investigation report was not available at tiie time this document -was written. Trichlproethylene: As shown in Figure 5, TCE was detected at most of the boring locations on the north. campus property atconcentrations above.the M.D.H Health Risk. Limit (HRL) of0.4 pp (parts per billion, which is the.;same as micrograms per liter). A HRL represents an amount of a contarninarit that poses little or.no health risk to those'drinking the water daily for a lifetime, including sensitive or highly exposed people. The highest concentration detected.was.189 pp.b, with the greatest concentrations found beneath or near the. Water Gremlin plant building. TCE was not detected. in borings near the north side of Lambert Creek or in borings on the south campus...TCE also was not detected to the north, west, or northeast of the. Water Gremlin plant. This suggests. that TCE may have a somewhat limited extent in the shallow groundwater. TCE has not been detected to date in any samples collected from the buried sand.aquifer. 23