The Johnson Company reviewed existing data to develop a conceptual model for the site to determine its potential impact on the river. We also reviewed tentative remediation plans that included the installation of a $10 million permeable reactive barrier between the site and the river. We identified and trained a local environmental firm to assist with regulatory negotiation, logistics, and field tasks.
We designed a unique method to investigate and evaluate the hyporheic zone that included:
- mobilizing all equipment and staff needed to conduct detailed field investigations
- installation of 60 mini piezometers along the river bank where the groundwater plume discharges
- sampling all mini piezometers for physical and chemical parameters and chlorinated compounds
- evaluating pressure head, temperature, specific conductance and dissolved oxygen to evaluate whether the river was receiving or losing water to the adjacent aquifer
- collecting groundwater samples from existing on-site monitoring wells
- interpreting groundwater chemistry and hydrogeology to evaluate the efficacy of remediation by natural attenuation, and
- surface water monitoring to assess impacts from groundwater contaminant discharge zones.
Using the results of field activities, The Johnson Company refined the site conceptual model and developed recommendations for future site remediation and management.
