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An active dry cleaner site located within a multi-use commercial development strip mall was impacted with high levels of PCE vapors. A subsequent investigation revealed groundwater impacts below the building and outside the building in a former filter storage area.
The original remediation plan involved a dual-phase extraction system with an estimated cost of approximately $1.3 million. An alternative approach consisting of in situ chemical oxidation (ISCO) coupled with enhanced reductive dechlorination (ERD) was proposed by KERAMIDA and ultimately selected by the funding source. To date, the ISCO/ERD approach has cost less than $200,000, including 2 years of monitoring and multiple indoor air/sub-slab vapor sampling events. $50,000 – $75,000 in additional remediation/monitoring is anticipated to achieve closure, resulting in an estimated total savings of $1,000,000 for this project being funded by insurance companies.
KERAMIDA developed a remediation work plan consisting of an ISCO injection into the permeable fill material directly beneath the floor of the dry cleaning space (Source Area), combined with a plume-wide ERD injection.
Injection points for both RegenOx® and 3-D Microemulsion® were installed inside the dry cleaner because there was insufficient clearance for the drilling equipment. The remainder of the ERD injection points outside the building were advanced using direct push technologies.
After approximately six months of post-injection monitoring, the data suggested insufficient bacteria were present to promote accelerated reductive dechloriation. Consequently, the bioaugmentation substrate BDI Plus was applied within the ERD treatment area. Graph to the right shows results from key well within this area.
As indicated above, the bioaugmentation substrate rapidly reduced the daughter products generated as a result of the initial electron donor injection. Two years of groundwater monitoring has been performed since the initial injection and CVOC concentrations in all of the wells, except one source-area well, are below the onsite remedial standard (groundwater migration to indoor airscreening level). In addition, two downgradient wells just outside the treatment area have slightly elevated TCE and VC concentrations.
A small supplemental injection is currently planned for the source area (to further reduce the VC concentration to below the screening level) and around the two off-site wells to reduce the minor cVOC concentrations to below residential levels so that deed restrictions are not required.
3-D Microemulsion is an engineered electron donor material that offers a novel 3-stage electron donor release profile, pH neutral chemistry and is delivered on-site as a factory-emulsified product.
RegenOx is an advanced chemical oxidation technology that destroys contaminants through powerful, yet controlled chemical reactions and not through biological means. This product maximizes in situ performance while using a solid alkaline oxidant that employs a sodium percarbonate complex with a multi-part catalytic formula.
Bio-Dechlor INOCULUM Plus is an enriched natural microbial consortium containing species of Dehalococcoides sp. (DHC). This microbial consortium has since been enriched to increase its ability to rapidly dechlorinate contaminants during in situ bioremediation processes.