At a glance
Location: Florida
Geology: Silty sand
Contaminant(s): Chlorinated solvent, DCE, PCE
ETEC Solution(s): CarBstrate, ISD system
Unique challenge(s): Active business
Site Summary
An active dry cleaner facility with PCE/TCE contaminated soil aimed to remediate while remaining open for business during the remediation process. An In Situ Delivery (ISD) system was applied in tandem with CarBstrate to treat both the contaminated soil and groundwater. The result was >99% reduction of PCE, TCE, DCE, and VC in the full-scale area.
Site conditions and remedial goal
The site was especially unique because of its close proximity to a number of active businesses. The source dimensions are 300 feet wide by 125 feet long with a saturated thickness of 15 feet with a total site volume of 21,000 cubic yards. The remedial goal of this site was to achieve effective elector donor delivery that promoted complete PCE/TCE dechlorination within months while the generated biomass continued to sustain dechlorination for months/years.
ETEC Solution
The In Situ Delivery (ISD) system was fabricated and installed by ETEC and was able to recirculate over 6 million gallons of groundwater over a 24 month timeframe. This recirculated groundwater was amended with 7,500 lbs. of CarBstrate - chosen for its high solubility and lack of any risk to human health. The unique challenge of ensuring the business remained operational was met with a directional drilling rig which allowed the installation to occur without disruption to the businesses and without trenching. Groundwater was extracted from 5 extraction wells and was distributed into the subsurface though 9 vertical injection wells and 3 horizontal injection wells. ETEC trained the local consultant to operate the In Situ Delivery (ISD) system and provided them with the appropriate substrate feed rate based on the mass of the chlorinated solvents. The extraction wells doubled as performance monitoring wells in addition to specific monitoring wells which enabled a highly accurate assessment of the effectiveness of the treatment.
Remedial outcome
The result of this project was overwhelmingly successful. All monitoring locations (MWs and EWs) showed a >99% decrease in total molar concentrations 24 months after recirculation/substrate addition began. Once recirculation ceased, only trace detections of VC remain at 2 locations (12-28 µg/L). This VC is co-mingled with 30 mg/L TOC and nutrients, and will attenuate rapidly over time as the aquifer becomes more aerobic. This project was a massive success and serves as an example of working within the unique parameters of an active business.