The subsurface of the property consists of unconsolidated overburden ranging from 7 feet thick at the upgradient extent and 16 feet deep at the downgradient extent of the property. These sediments consist of relatively coarse (sand) and fine (clay) sediments that overlie sedimentary bedrock of the Brunswick Formation, extending to depths of hundreds of feet below ground surface. The Brunswick Formation is composed of fine-grained sediments that are cemented together with little or no interstitial porosity and well yields are typically less that 1 gallon per minute. Vertical and horizontal fractures are randomly spaced and distributed throughout the rock. Secondary fracture porosity is principally oriented along bedding planes.
Targeted Environmental Media:
 Fractured Bedrock
Ground water contaminated with volatile organic compounds (VOC) are exiting the property through fractures in the bedrock, unconsolidated sediments above the bedrock, and through Sheffield Brook.
Major Contaminants and Maximum Concentrations:
- Tetrachloroethene (0 µg/L)
No technologies selected.
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
Comments:
In 1991, source area soils from a former storage yard at the site were excavated and removed for off-site disposal. Post-excavation testing demonstrated that contaminated soils were adequately removed. Ground water monitoring showed the site to have established an equilibrium condition of dissolved-phase migration with minor attenuation as a result of the reduced mass of the source area.
In response to the New Jersey Department of Environmental Protections (NJDEP) requirement for more aggressive action at the site, Hydrogen Release Compound (HRC) was identified as an innovative remediation alternative. Approximately 16,000 pounds of HRC was injected at a total of 200 locations within a high-density injection grid during September and October 2001.
Post-injection quarterly ground water monitoring commenced in December 2002.
None provided
Reductive dechlorination of tetrachloroethene (PCE) was immediately evident within the first post-injection monitoring event. Overall, the data show a favorable response to HRC injection. There has been a 99 percent reduction in PCE within the high-density injection grid.
Post-injection concentrations of PCE indicate that PCE has declined to less than 10 percent of the total VOC mass. 1,2-Dichloroethene (DCE) increased to 85 percent of the mass of VOCs present. Concentrations of vinyl chloride (VC) also increased. Concentrations of PCE on the leading fringe of the treatment area have exhibited reductions of more than 50 percent. Targeted reinjection of HRC into perimeter portions of the plume is planned along with attenuation monitoring for the residual PCE mass.
Locations where HRC was injected into a bedrock well under pressure have achieved better results than at neighboring wells where HRC was passively released into the aquifer.
Costs to conduct the enhanced in situ bioremediation treatment at the site are $250,000. The use of HRC at the site has realized a significant cost savings and greater effective results when compared with conventional ground water remediation technologies.
References:
Nachlas, Paul E.; Ted Tesler. 2003. HRC Remediation of PCE at a New Jersey, Printed Circuits Site. The Seventh International In Situ and On-Site Bioremediation Symposium, Orlando, Florida, June 2-5.
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