Trihydro provides ongoing environmental services to address chlorinated solvent impacts at an industrial facility, including regulatory compliance and groundwater remediation.

Trihydro is performing ongoing work at a site under U.S. Environmental Protection Agency (USEPA) and New Jersey Department of Environmental Protection (NJDEP) oversight and the requirements of a USEPA Hazardous and Solid Waste Amendments (HSWA) permit. The work is being performed to address extensive chlorinated solvent impacts in soil, bedrock, and groundwater. Various ketones are also present at high concentrations.

Trihydro designed and implemented a complex site investigation to delineate the extent of impacts in groundwater at six solid waste management units (SWMUs) and three Areas of Concern (AOCs). Over 80 monitoring wells were installed and sampled in three water-bearing zones including fractured bedrock.  Multiple dissolved-phase chlorinated solvent plumes extending offsite from the facility were delineated. The vapor intrusion to indoor air pathway was investigated in two offsite buildings and dismissed. Extensive well to well aquifer testing was performed to map out fracture interconnection and delineate a stacked sequence of five water-bearing bedding-plane fractures controlling plume migration in the bedrock. Trihydro’s thorough evaluation of geologic and hydrogeologic conditions at the site and integration into a detailed conceptual site model (CSM) clarified the understanding of site conditions. This led to the conclusion of the delineation phase of work and successful dismissal of a number of unusual regulatory agency interpretations and costly investigatory ideas resulting in cost savings.

Trihydro is guiding the remediation phase of work toward a final remedy that will cap and leave residual impacts in place and control groundwater through a sitewide groundwater extraction and treatment system. The system includes bedrock groundwater extraction and provides hydraulic control of groundwater contamination, treatment of extracted groundwater to remove volatiles and inorganics, and discharge of treated water under permit to the municipal sewer system. Trihydro performed the evaluations and permitting necessary to add another well to the groundwater extraction system to expand the capture zone and satisfy conditions for incorporation of the system into a final remedy for groundwater. Optimization of the treatment system is ongoing and is focused on system upgrades and testing that may lead to the elimination of an inorganic treatment circuit that will lower operating costs. 

An innovative approach for screening vapor intrusion incorporated the use of passive diffusion bag (PDB) sampling of groundwater in monitoring wells to provide for more representative assessment of shallow groundwater quality, which eliminated the need for indoor air sampling at a number of off-site structures.

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