Overcoming Technical and Financial Challenges to Achieve Site Closure

EnviroForensics helped guide two former dry cleaner sites in Wisconsin through a complex environmental and regulatory process involving decades-old releases, evolving cleanup expectations, bedrock contamination, and vapor intrusion concerns. By combining advanced investigation tools, targeted remediation, long-term monitoring, regulatory coordination, and historical insurance recovery approach, EnviroForensics helped find funds needed to complete the investigation and remediation, resolve long-standing liabilities, and achieve closure at both sites.

The projects demonstrate how technical rigor and financial strategy can work together to bring even challenging dry cleaner sites with persistent contamination to a successful outcome.

Background

The two former drycleaners operated for decades using perchloroethylene, commonly known as PCE, a chlorinated solvent historically used in dry cleaning operations.  Initial environmental investigations began as early as the 1990s, with additional work conducted over time as more information became available and regulatory expectations evolved.

At one site, impacts were generally consistent with many historical dry cleaner releases, with affected soil and groundwater located near former operational areas.  At the second site, the environmental conditions were significantly more complex. Historical releases had migrated far beyond shallow soil and impacted three separate aquifer systems: shallow soil, fractured dolomite bedrock, and underlying sandstone.

Ultimately, more than 80 monitoring wells were installed at the more complex site, many extending deep into bedrock, to characterize the extent of chlorinated solvent impacts. Both sites also required ongoing vapor intrusion assessment, groundwater plume delineation, and coordination with the Wisconsin Department of Natural Resources.

The Challenge

The long history of releases created several layers of complexity. Historical site conditions had to be reconstructed, prior investigation files needed to be reviewed and interpreted, and the technical team had to evaluate how contamination had migrated over time.

Vapor intrusion was also a concern. Sampling identified chlorinated vapors beneath nearby residential and commercial buildings.  Addressing these risks required a comprehensive evaluation of soil gas, sub-slab vapor, and indoor air.

The most significant challenge was the contamination within fractured bedrock at one of the sites. Chlorinated solvents had migrated vertically and laterally through the bedrock in unpredictable patterns. These conditions required high-resolution characterization and a remediation design capable of addressing contaminants in deep, low-porosity rock.

The cost of investigating and remediating widespread bedrock contamination can be substantial. To help address the financial burden, EnviroForensics also supported a historical insurance recovery strategy. Insurance archaeology was used to reconstruct legacy insurance coverage and help the responsible party access funds needed to advance investigation and cleanup.

The Solution

EnviroForensics developed a strategy that combined intensive site characterization, advanced in-situ remediation, vapor intrusion evaluation, long-term monitoring, and insurance archeology.

At the more complex site, detailed geophysical analysis, including rock coring and televiewer logging, provided insight into fracture networks controlling contaminant migration. This information allowed EnviroForensics to refine the conceptual site model and focus the remedy on the 50–60-foot bedrock interval where contaminant mass was concentrated.

EnviroForensics then designed and implemented a full-scale application of PlumeStop™ Liquid Activated Carbon™ through a 21-well injection network. This innovative remedial approach created a permeable treatment barrier within the fractured rock to help halt plume migration and support contaminant breakdown.

At the second site, where contamination impacts were relatively more localized near the areas of dry cleaning operations, EnviroForensics designed, installed, and operated a soil vapor extraction system. The system was used to remediate soil impacts, prevent further contaminant migration to groundwater, and mitigate vapor intrusion.

Outcome

Results from post-remedial groundwater and vapor monitoring at both sites demonstrated declining contaminant trends and sustained vapor risk reduction.  The data showed that the selected remedies were effectively controlling remaining impacts and that the vapor intrusion had been addressed.

Ultimately, EnviroForensics prepared and submitted closure documentation demonstrating that groundwater contaminants were stable or declining, vapor intrusion risks were mitigated, and the selected remedy effectively controlled remaining impacts, and additional remedial measures were not warranted. The Wisconsin Department of Natural Resources accepted the closure packages, resulting in regulatory closure for both former dry cleaner sites.

Importantly, both sites achieved closure without the need for long-term vapor mitigation system operation or land use restrictions.

After decades of investigation, changing regulatory expectation, and complex environmental conditions, the long environmental liabilities associated with both properties were resolved. The properties are now positioned for safe and productive use.

These projects show that even complicated dry cleaner sites involving deep contamination, fractured bedrock, vapor intrusion concerns, and significant cleanup costs can be brought to closure when the technical approaches, regulatory strategy, and funding strategy are aligned.