DHEC’s South Carolina Drycleaning Facility Restoration Trust Fund (DFRTF) team with engineering services provided WSP USA Inc. (WSP, formerly Ecology & Environment, Inc.) earned a National Recognition Award for exemplary engineering achievement in the American Council of Engineering Companies’ (ACEC) 54th annual Engineering Excellence Awards (EEA) for performing environmental assessment and contamination remediation statewide at former dry cleaning facility sites enrolled in the DFRTF program.
Konstantine Akhvlediani, Robert Hodges, and LaJoyce Perkins-Alexander compose the agency team and their mission is to clean up contaminated dry-cleaning sites using state contractors, all of which is paid for from the trust fund. The team administers the fund and directs and oversees the cleanup activities.
Preliminary assessment (PA) was performed at 420 former dry-cleaning facility sites to determine the magnitude of environmental contamination resulting from the use of various chemicals. Of these, 100 sites were closed where no impact was found and more than 300 sites had chemical residue that posed a risk to private and public drinking water wells. Following the PA risk-based ranking of sites, comprehensive remedial investigations beginning with sites exhibiting with the highest potential risks to drinking water sources was initiated.
Dry-cleaning solvent impacts to groundwater and soil were evaluated by identifying source areas and delineating the extent of dissolved contaminants using rapid vertical profiling techniques for sample collection combined with a highly effective and innovative field-based colorimetric screening method for low-level detection of chlorinated compounds. WSP specifically developed this screening method to facilitate real-time decision making and strengthened overall data quality resulting in significantly accelerated process of source identification and dissolved contaminant delineation.
Once fully characterized with contaminant fate and transport determined, each site was reprioritized. Sites presenting the greatest risk were addressed through design and implementation of various remedial actions including source removal, in-situ chemical oxidation, in-situ biostimulation, and/or monitored natural attenuation.
A special approach was designed to rapidly evaluate the Vapor Intrusion Potential (VIP) of contaminant impacts to the sub-slab soil gas and indoor air facilities currently occupied by non-dry cleaning-related businesses. At sites with indoor air concentrations exceeding target cleanup concentrations, the team designed and implemented an approach to mitigate the indoor air impacts using a modified Sub-Slab Depressurization System (SSDS). Originally designed for radon mitigation, this system requires minimal design modifications and utilizes readily available system components.
This significantly minimized design and construction costs. Most SSDS systems achieved target Vapor Intrusion Screening Levels for drycleaning related compounds within 30 days of startup. The SSDS systems also provide significant removal of chlorinated solvent mass from the sub-slab soils. To date, the systems have collectively removed over 800 pounds of tetrachloroethylene from beneath former DC facilities.
The project also received the additional honor of Diamond Award from ACEC New York this year representing engineering excellence from throughout the nation and the world. Judging for the awards program—known industry-wide as the “Academy Awards of the engineering industry”– took place in February and was conducted by a national 20-member panel of built-environment leaders, along with experts from government, media, and academia. Award criteria focused on uniqueness and originality, technical innovation, social and economic value, and generating excitement for the engineering profession.
Recognition of all award winners including top winners—20 Honor Awards, 16 Grand Awards, and the prestigious “Grand Conceptor Award” for the year’s most outstanding overall engineering achievement—took place during the 2021 Virtual EEA Gala, held Thursday, June 17, 2021.