Former Appliance Manufacturing Plant

Project Summary

A former appliance manufacturing plant located in São Paulo, Brazil was contaminated due to historic operations. Soil and groundwater were impacted with chlorinated volatile organic compounds (CVOCs), including tetrachloroethylene (PCE), trichloroethylene (TCE), cis-1,2-dichloroethene (cis-1,2 DCE), vinyl chloride (VC), and 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA). PCE was the most widespread and concentrated contaminant of concern in groundwater, with concentrations reported greater than 200,000 µg/L.

The hydrogeological model is complex, with the vertical treatment zone being divided into four hydraulic layers with confining clay zones. The shallowest zone was considered most important for remediation due to the potential for vapor intrusion impacts.

Remediation Plan

The remediation plan developed by the consultant included the combination of multiple technologies to remediate soil and groundwater across the 113,000 sq ft groundwater plume. Initial excavation was utilized to remove shallow, densely impacted clayey soils where injections were not feasible. Multi-phase extraction was used in hot spots areas, with soil vapor extraction used in the neighboring buildings to mitigate potential exposure to residents.

In-situ chemical reduction (ISCR) with Provect-IR® was utilized in most of the plume across multiple vertical hydraulic zones. The efficacy of Provect-IR® was first confirmed via bench testing, which was followed by field-scale pilot tests. The final remediation plan included 600,000 lbs of Provect-IR® that was injected via 537 direct push points ranging in depth 13 to 56 feet below ground surface.

Results

• Following Provect-IR® application, monthly pH and ORP readings confirmed that conditions conducive to ISCR had been established.
• Groundwater conditions rapidly became anaerobic following Provect-IR® injection, and total CVOCs in soil and groundwater were reduced by 89%.
• Many targeted monitoring wells had all CVOC concentrations below calculated site-specific target levels.
• No observed rebound in parent compounds (PCE and TCE).
• Significant PCE plume contraction with further contaminant reductions anticipated.
• Current site conditions continue to exhibit favorable ISCR geochemistry with sustained treatment effectiveness.