Challenge. Determine environmental liabilities associated with potential impacts to soil and groundwater from chlorinated solvents prior to a potential sale of a portion of the general office facility.
Solution. As part of a preliminary site investigation (PSI) to confirm recognized environmental concerns (RECs), INTERA installed and sampled three clusters of soil gas wells that revealed low concentrations of chlorinated solvents (TCE and TCA) in soil vapor at various locations within the office complex. To further define the nature and extent of these contaminants in the vadose zone and groundwater, we designed, drilled, and installed a dual-purpose (i.e., groundwater and soil vapor) monitoring well to a depth of 385 feet using sonic drilling and sampling techniques. In addition to the groundwater monitoring well screen, five soil-vapor sampling ports were attached to the outside of the polyvinyl chloride casing at depths identified during the drilling as potentially containing volatile organic compounds. While the NMDOT ultimately decided not to sell the portion of the office complex property, results of soil-vapor and groundwater monitoring showed that no contaminants of concern (COCs) were present in groundwater and that the concentrations of COCs in soil vapor were not indicative of an on-site source.