Illinois Manufacturing Plant

This former manufacturing plant had at least four degreasing pits within the facility including underground piping and outside underground storage tanks (USTs), previously removed, for fresh and spent TCE solvent.

Some vadose zone soil was impacted, which was remediated through soil vapor extraction while groundwater was impacted in multiple locations extending to 70 ft depths. The highest groundwater solvent concentrations were located at MW-674, adjacent to a former degreaser, where TCE concentrations above 2,000 mg/L were measured.

Two zones of groundwater are present: the shallow, starting typically between 12 and 20 ft bgs, and a deeper zone between 45 and 70 ft bgs.

A total of 164,500 pounds of EZVI was injected over two periods:

• Shallow injections in April 2007 (8-22 feet depth)
• Deeper injections in November 2007 (extending to 70 feet via direct injection)

This Illinois manufacturing plant project demonstrates one of IET's largest-scale EZVI (Emulsified Zero-Valent Iron) deployments — 164,500 pounds injected across two treatment periods targeting TCE DNAPL source zones at depths from 8 to 70 feet below ground surface. EZVI is a patented technology originally developed by NASA, using nanoscale ZVI particles suspended within a biodegradable emulsion that directly contacts and dechlorinates DNAPL chlorinated solvents in the source zone.

The two-phase injection strategy — shallow injections in April 2007 (8–22 feet) followed by deeper injections in November 2007 (extending to 70 feet via direct injection) — addressed contamination across multiple groundwater zones. The multi-depth approach ensured that both the shallow and deep aquifer zones received effective EZVI delivery, with the emulsion contacting TCE DNAPL at the soil-water interface where conventional dissolved-phase treatment technologies cannot reach.

The 2,000+ mg/L TCE concentration at the source area (MW-674) represents an extremely high-concentration DNAPL source zone — the type of contamination that biological ERD alone cannot treat due to microbial toxicity at high solvent concentrations. EZVI's abiotic dechlorination mechanism directly destroys DNAPL mass without requiring microbial activity, making it the logical choice for these aggressive source zones. The no-rebound result and effective treatment in tight geology confirm the technology's suitability for challenging manufacturing site conditions.

The former Illinois manufacturing plant site contained four degreasing pits and TCE solvent USTs — a common contamination scenario at historical industrial facilities where chlorinated solvents were used for metal degreasing and parts cleaning. The TCE released from these operations migrated as a DNAPL through the vadose zone into the underlying groundwater, creating source zones at multiple depths. The combination of soil vapor extraction (for vadose zone soil) and EZVI injection (for groundwater source zones) provided a comprehensive treatment approach addressing both the soil and groundwater contamination pathways.

The tight geology noted in the Key Success Factors indicates low-permeability soils — likely clay or glacial till common in Illinois — that challenge conventional reagent distribution. EZVI's emulsion-based delivery system is particularly effective in these conditions because the emulsion can be distributed under pressure through tight soil matrices, and the biodegradable oil phase slowly releases the ZVI particles over time, providing sustained treatment even in low-permeability settings where rapid reagent transport is not achievable.