Formatted Title

Expedited Site Investigation and Dynamic Remedy Deployment to Reduce Environmental Risks and Long-Term Liability

Background/Objectives

The goals of meeting regulatory objectives, reducing exposure risks, and reducing long-term liability for potential exposures in the future often takes a significant amount of time. This leads to frustrations within project teams, responsible parties, and potentially exposed parties. The limitations to reducing risks and liabilities in an expedited manner often focus on costs, decision-making timelines, access, stakeholders engagement, contractor availability, and responses from agencies. The objective of this presentation will be to:

1. Demonstrate the multiple levels of engagement required amongst the parties involved in a project to reach regulatory goals and reduce short term liabilities.
2. Present multiple approaches to implementing a dynamic investigation that includes standard and high-resolution site investigation techniques.
3. Establish a data-driven approach to establishing longer term monitoring networks.

Approach/Activities

In conjunction with cooperating parties, ERM conducted site investigation and interim remedy activities at a site where a release occurred approximately 50-75 years prior to the start of investigation activities. Data from the site investigation work indicates that dissolved-phase groundwater and soil gas impacts, albeit at low concentrations, are present in both on- and off-site areas. Additional work, including bedrock investigations, indicated that impacts are present within a discrete fracture network. Within 2 years of registering the site in a voluntary environmental regulatory program (5 years since the dynamic investigation began), over 500 data points (permanent/temporary) were collected including bedrock boreholes, bedrock wells, overburden monitoring wells, soil gas monitoring wells, Waterloo^APS borings, MIHPT borings, test pits, and soil borings, along with a variety of surface and downhole geophysical surveys to expand the conceptual site model and understand the risks associated with contamination in site media.

In parallel with the site investigation activities, interim remedies were deployed to reduce contaminant mass and interrupt completed exposure pathways. The interim remedies included the deployment of multiple SVE systems at targeted areas of the site and demolition of homes to prevent potential exposure risks in the short and long term. Decisions were made over the course of the project to manage risks via land acquisition to prevent future construction and occupancy. In addition, multiple phases of pilot testing were deployed to determine the efficacy of those technologies in the short and long term. The work on this project was done in direct cooperation with the regulators in charge of the project and communication with third parties as necessary to provide transparency around the intentions of the activities implemented through the project.

Results/Lessons Learned

To reduce the short- and long-term liabilities regarding contamination present in multi-media in an expeditious manner, a dynamic and fluid approach to the investigation, remediation, public engagement, and stakeholder engagement was deployed. This work was done in a very short amount of time compared to other sites with chlorinated solvent contamination to the satisfaction of the regulatory agency. This approach resulted in the reduction of long-term liabilities and costs associated with the project by quickly eliminating identified residential exposure risks, deploying SVE systems, and deploying multiple pilot and interim remedies in bedrock and overburden groundwater within just 2 years.