U.S. Army Corps of Engineers – New York and New England Districts

Army Corps of Engineers – New York and New England Districts

Overview:

• Multiple Remedial Investigations at a Formerly Used Defense Site
• Vapor Intrusion investigations
• Long-term monitoring
• Munitions and explosives of concern

Description:

Avatar has worked under several different contracts for USACE at the former Raritan Arsenal in Edison, NJ since the early 2000s. The former Raritan Arsenal is a Formerly Used Defense Site (FUDS) encompassing approximately 3,200 acres along the banks of the Raritan River in Edison, New Jersey. It was used by the U.S. Army from 1917 to 1963. Operations at the site included the receipt, storage, shipment, and/or decommissioning of ordnance, arms, and machinery. Some waste material, including ordnance and chemical agents, were reportedly buried on-site or were destroyed by surface burning or burning in chambers or pits. Accidental explosions in magazine buildings and outdoor storage areas reportedly scattered explosive materials over large areas, and drove ordnance fragments into the ground.
Click to view layout of Raritan area

Remedial Investigations

Avatar developed Remedial Investigations (RIs) for hazardous and toxic waste (HTW) concerns at three areas. The areas investigated by Avatar range in size from approximately 170 acres to 865 acres. The RIs along with the risk assessments are CERCLA-compliant. Avatar prepared all required Quality Assurance Project Plans in accordance with UFP. The human health risk assessments (HHRAs) evaluated human health risks from soil exposure to a variety of potential receptors. The mixed use of the former Raritan Arsenal required the application of multiple, site-specific exposure scenarios including commercial/industrial, residential, recreational, and trespassing, among others. The outcome of the site-specific risk assessments are being used to support the No Further Action (NFA) alternative.

One of the primary challenges encountered during the HHRAs was the historical source of the contamination found in site soil. Since the Army ceased operations in 1963, the area has undergone significant development. The development activities and the subsequent use of the area has introduced potential sources of contamination that cannot be attributed to historical Army operations. Avatar has performed a number of evaluations ranging from desk-top statistical evaluations to field-based studies to investigate this issue. Avatar demonstrated that a significant portion of the contamination is not attributable to the Army, reducing risk.

In addition to the HTW RIs that are being performed, Avatar has also been tasked with developing RIs for munitions and explosives of concern (MEC) at two areas. The RIs, which include MEC Hazard Assessments, are underway and will be accompanied by Proposed Plans and Decisions Documents focusing on MEC.

Vapor Intrusion (VI) Investigations

Avatar has conducted VI investigations and monitoring at six buildings at the former Raritan Arsenal that are potentially impacted by subsurface (groundwater) contamination related to past Army activities. The VI investigations are a continuation of an ongoing Indoor Air Quality program that is part of USACE’s remedial strategy of natural attenuation as a means of addressing remaining groundwater contamination resulting from historical Army activities.

The VI investigations were performed for buildings with a combination of uses. A tenant of one of the buildings operates a daycare facility. Avatar performed 10 sampling events for this project with a total of approximately 65 air samples collected during each event. A situation emerged that required an emergency sample collection effort. Elevated levels of tetrachloroethene (PCE) were unexpectedly observed in indoor air samples collected from the daycare facility. Shortly after the results were known, a visual inspection and scans with a photo-ionization detector were performed within the suspected source area to identify the source. The source, a product containing PCE, was identified in a warehouse space adjacent to the daycare facility. The source was removed and the indoor air was re-sampled. The emergency re-sampling effort confirmed that the source was removed and the PCE levels were no longer a concern.

Avatar is also performing annual O&M inspections of existing subslab depressurization systems at five buildings to ensure the systems are operating properly. Avatar assisted with the optimization of vapor mitigation systems to reduce overall energy consumption at three buildings.

Long-Term Monitoring

Avatar completed groundwater compliance monitoring in September/November 2017 to demonstrate that monitored natural attenuation (MNA), the selected remedial action strategy for shallow groundwater, is occurring. Samples for VOC analysis were collected from 51 wells and were presented in the 3rd Groundwater Compliance Monitoring Progress Report for the site. The report concluded that the extent of the plumes has decreased and that natural attenuation is occurring.

Data Management

All environmental chemistry data were incorporated into a site-wide Data Inventory database that contains multi-media sample results from the previous 25 years of investigations. This inventory is routinely shared with USACE and other contractors to allow for a streamlined approach for data management and interpretation. Further, Avatar has incorporated all project data into FUDSCHEM, USACE’s online repository for electronic data and documents supporting the FUDS program.

Multiple investigations have been performed at the former Raritan Arsenal over the last 25 years to address HTW and MEC. Previous investigations ranged from Phase I Site Investigations to large scale removal actions of contaminated soil and MEC. Comprehensive reviews of all previous documents were performed along with data management and GIS-related tasks. Often, multiple investigations occurred within an area including multiple sampling efforts, geophysical surveys, and identification and removal of MEC items. Avatar developed a set of comprehensive site GIS figures for each area that displayed the results of all relevant HTRW and MEC investigations to provide USACE, independent reviewers, and project stakeholders a single location to review all work performed to date.