Multi-Area ISRA Project – Innovative Remedies
Location: New Jersey Research and Development Laboratory
Regulatory Program: Industrial Site Recovery Act (ISRA)
Duration: February 2000 to Present
Summary: Complex, multi-media investigation and remediation project; soil removal adjacent to buildings and electrical utilities in two areas; innovative groundwater trace-metals characterization and chloroform source assessments; cost-effective and practical remedy development; LSRP services and application of advantageous provisions of SRRA.
Soil cores showing oxidized (reddish-brown) and unoxidized (black) aquifer matrix materials following a property transfer in late 1995, this telecommunications industry client-initiated activities necessary for regulatory closure of this research and development laboratory site, under New Jersey’s Industrial Site Recovery Act (ISRA). Initial activities performed by the client included signing a Remediation Agreement and submitting Preliminary Assessment (PA) Reports for this and five other ISRA-subject sites.
Since early 1996, Mr. Peterson has provided all project management and technical consulting services in connection with one of the project sites and Princeton Geoscience has served as the project consultant since its formation in February 2000. Since the adoption of New Jersey’s Site Remediation Reform Act (SRRA) in 2009, we have served as the Licensed Site Remediation Professional (LSRP) of record for the site.
Site characterization activities included developing, implementing, managing and reporting for work activities, during ISRA Site Investigation (SI) and, Remedial Investigation (RI) phases of work. The PA Report identified 28 potential Areas of Concern at the site. Sampling and other evaluation required during the SI focused on 19 of these areas, including decommissioned septic systems, underground chemical wastewater piping, sumps, underground storage tanks, stormwater sewers, a detention basin, and transformers.
Based on the SI results, Princeton Geoscience performed an RI to evaluate the extent of contamination at four areas, and to evaluate hydrogeologic conditions and groundwater quality across the site. Hydrogeologic investigations required consideration of several Coastal Plain geologic formations, multiple areas of aquifer recharge, complex flow conditions, and groundwater discharge into two wetland areas. Naturally elevated concentrations of several trace metals were associated with Princeton Geoscience employees sampling groundwater on-site minerals of the aquifer matrix, which necessitated the development of specialized sampling and statistical evaluation procedures to obtain a representative characterization of natural vs. facility-related groundwater impacts. A well search and water supply survey and a Baseline Ecological Evaluation were conducted in conjunction with contaminant fate and transport analysis, to assess the potential impact to receptors.
Based on the completed SI and RI, No Further Action status was obtained for 26 of the 28 Areas of Concern identified during the PA. Active remediation was required in four areas, including:
- An area of PCB-contaminated soil adjacent to an active transformer
- An area of pesticide-contaminated soil in a landscape bedding area was identified during sampling along delivery lines leading to a septic system
- Groundwater impacted by nitrate, ammonia, and trace levels of chlorinated organic compounds near a decommissioned septic system leachfield
- Groundwater impacted by chloroform downgradient of a parking lot and concrete walkway
Soil Remedial Actions
Princeton Geoscience designed and managed the implementation of removal actions to address the PCB- and pesticide-impacted soils at the transformer and landscape bedding areas. Challenges included performing excavation work safely in immediate proximity to the main facility building and in an area of active, high-voltage electrical units and subsurface utilities, and ensuring effective containment of excavated soil and prevention of dust transport of contaminants at this occupied facility.
A total of 450 tons of non-hazardous waste soil were excavated and transported offsite for recycling at a mine reclamation site in eastern Pennsylvania. The excavation and restoration was completed over three weekends, allowing facility activities to proceed without interruption during the work week.
Groundwater Remedial Actions
Abandoned Septic System Area
Site groundwater during sampling, Bench-scale treatability and field pilot studies were completed to evaluate the feasibility of implementing enhanced, in-situ bioremediation for nitrate, ammonia, and chlorinated organic compounds in groundwater near the abandoned septic system leachfield. Based on the positive results of these innovative studies, a full-scale remedy was considered which incorporated two separate treatment zones (permeable reactive barriers) along the groundwater flow path.
In the leachfield area, oxygen-releasing compounds were to be injected to establish a nitrification enhancement zone, where sorbed ammonium would be converted under aerobic conditions to nitrate, a more mobile nitrogen compound. Downgradient of the leachfield, oxygen scavenging compounds and a carbon source material would be injected to create a denitrification enhancement zone, where nitrate formed in the leachfield area would be “cut off” by anaerobic denitrification processes. The anaerobic conditions and available carbon source would also facilitate reductive dehalogenation of the chlorinated organic compounds found at low concentrations near the leachfield. Excavation and conventional pump and treat alternatives were ruled out due to their cost and partial effectiveness.
In 2004, the New Jersey Ground Water Quality Standard (GWQS) for ammonia was increased by a factor of six, to 3.0 mg/L. In light of this development, Princeton Geoscience determined that a simpler remedy based on the discharge of oxygenated, pH neutral potable water to the former leachfield piping might be appropriate. Field pilot testing over a 90-day period indicated this approach reduced nitrate and ammonia concentrations to below the GWQS, with only limited rebound following the cessation of the potable water discharge. We attributed the contaminant concentration reductions to dilution, flushing, and geochemical and microbial changes coincident with the potable water discharge.
In 2009, Princeton Geoscience began its role as LSRP of record for the project. We identified and have applied a provision of the Response Action Outcome (RAO) technical guidance issued under SRRA, allowing use of monitored natural attenuation (MNA) for the remaining low-level, non-decreasing groundwater impacts in the former source and plume areas. This approach was supported by long-term statistical analyses, and assessment indicating receptors will not be at risk.
Chloroform Plume Area
The source of the chloroform in site groundwater was initially unclear because the plume appeared to originate in a relatively undisturbed, wooded area of the site, away from any known or likely past chemical releases. To define the extent and source of the chloroform concentrations in groundwater, Princeton Geoscience conducted a detailed delineation program using direct-push (i.e., Geoprobe®) groundwater sampling techniques and in-field analyses by an NJDEP-certified mobile laboratory.
This effort showed that the plume in fact originates in a wooded and grass-covered area traversed by a Princeton Geoscience employee sampling groundwater concrete sidewalk and stairway at the downgradient edge of a paved parking lot. Potential sources such as leakage along sanitary sewer lines or water lines were ruled out, based on the locations of these utilities and the distribution of chloroform in groundwater. Since their construction in the mid-1980s, the parking lot and concrete walkway have been treated with salt for snow and ice removal. Runoff of deicing meltwater to adjacent organic topsoil takes place in this area.
Based on a literature search and review of site conditions, Princeton Geoscience identified alternate mechanisms that explain the chloroform occurrence. Specifically, we concluded that natural in-situ halogenation of soil organic matter, augmented by influxes of low pH, chloride-containing runoff associated with the deicing salt applications, caused the enhanced formation of chloroform in the soil zone, leading to the observed groundwater impact. Princeton Geoscience developed and NJDEP approved a remedial plan for this area consisting of roadway deicing Best Management Practices and groundwater monitoring.
Upon assuming responsibility as LSRP of record for the site, Princeton Geoscience identified final actions needed to support the issuance of a Site-wide RAO. Recently completed work has included identifying and conducting SI sampling at two AOCs (elevator and historic pesticide application area) not addressed in the PA conducted by the client and at a previously unknown extension of an existing AOC (subsurface laboratory wastewater sewer piping). This follow-up characterization was conducted in an expedited manner using an adaptive analytical approach, accomplishing complex characterization objectives with minimal disturbance to facility operations. The program was designed so that data needs related to contaminant delineation, and potential application of NJDEP’s Attainment and various Impact to Groundwater technical guidance provisions would be met during a single sampling episode. Results of these assessments supported the conclusion that no remediation is required in this area.
Additional activities completed under LSRP oversight have included the development of information and monitoring programs for soil and groundwater Remedial Action Permits (RAPs) established by NJDEP; biennial monitoring, inspection, and certification pursuant to the RAPs; developing and certifying remedial cost estimates for the Remedial Funding Source (RFS) and Financial Assurance (FA); and updating the Vapor Intrusion assessment, Receptor Evaluation and Public Notification initiated earlier in the project. At present, we are preparing a Remedial Action Report for the septic system area groundwater and a supplemental SI Report for the recently completed follow-up characterization. These documents and the extensive pre-SRRA project history will support a Site-wide RAO, which we expect to issue during 2014.