Landmark conducted multiple rounds of soil and groundwater sampling on the St. Croix Valley Hardwoods facility and across the downtown portion of Luck, Wisconsin to demonstrate that chlorinated solvents originated from two separate offsite upgradient sources including a laundromat and a former telephone company. The delineation effort involved a detailed investigation to show how co-mingled plumes from several sources migrated at various depths within a drinking water aquifer, how seasonal fluctuations in the groundwater flow direction affected plume dimensions, and how former and current sanitary sewer mains in the downtown area provided multiple points of releases. Initially, Landmark mapped the plumes using a Geoprobe drill rig equipped with a mobile laboratory so that real-time data could be evaluated in the field and guide subsequent investigation locations. This saved the client time and money so that the field effort could be completed without multiple mobilizations. After the plumes had been adequately mapped, Landmark supplemented two existing monitoring well networks with the installation of five nested monitoring wells, strategically located to demonstrate the various contaminant sources. Because contaminant migration was heavily influenced by the intermittent pumping of the City well field, Landmark worked closely with the municipality to document operations.
After developing a team approach with the Wisconsin Department of Natural Resources and the Client, Landmark was able to prove that the St. Croix Valley Hardwoods property was not the source of chlorinated solvent impacts to groundwater. The Wisconsin DNR issued an Off-Site Exemption determination, which helped to facilitate the sale of the St. Croix Valley Hardwoods property.