After being retained to provide a review of this contaminated industrial site’s existing remedial approach, GZA was asked to suggest a more cost-effective remedial optimization of the system and provide potential closure alternatives.
A remedial approach and Operations, Maintenance, and Monitoring (OM&M) program was established by others at this active site which has a history of more than 100 years of industrial/manufacturing use. Previous site investigations had identified chlorinated volatile organic compound (cVOC) contamination in groundwater and soil beneath the site. Due to the presence of contamination in the subsurface, cVOCs were detected in soil gas. The Interim Remedial Measure implemented by others in 2009 comprised a sub-slab depressurization system (SSDS) to address vapor concentrations under the building and an Air Sparging/Soil Vapor Extraction (AS/SVE) system to treat contaminated groundwater and capture contaminant vapors from groundwater sparging. With these systems operating continuously since 2009, the operations, maintenance and monitoring costs were very high, and closure was not evident.
GZA was retained in 2019 to evaluate the efficacy of the remedial technology and to provide recommendations to enhance additional recovery of VOCs to expedite closure. GZA was appointed to monitor, maintain, and operate the system and implement a closure path. GZA optimized the system and, after a period of conducting continuous operation, GZA assessed the remediation’s effectiveness. GZA executed a rebound study: the AS/SVE system to collect baseline groundwater and soil vapor samples was shut down for approximately two years and, per NYSDEC requirements, GZA has conducted quarterly groundwater and soil gas sampling. Contaminant levels have remained within regulatory limits, as expected. Closure is expected by the end of 2023 in groundwater.
GZA's remedial optimization review resulted in a closure alternative that saves the client significant amounts of money while continuing to comply with regulatory deadlines and advance the site towards regulatory closure.