Assessment of Monitored Natural Attenuation for Fort Dix Army Installation

Problem

A Remedial Investigation was being conducted for the U.S. Army at the Fort Dix, N.J installation, resulting from groundwater petroleum impacts by leaking underground storage tanks. Multiple tank removals were performed at various locations within the facility. Pelorus was hired to develop a supplemental site characterization work plan and interface with the prime contractors to collect the appropriate data for an assessment of MNA as a remedial alternative.

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Solution

Pelorus was contracted to develop a monitored natural attenuation sampling and analysis program to evaluate groundwater quality and extent of contamination on each of the three sites within the Fort Dix Facility. A preliminary assessment based on an incomplete historical data set indicated that one plume had already reached NJDEP regulatory levels for benzene but was above background levels for iron content. One of the sites appeared to be a retracting plume and the third site required additional plume delineation before an accurate modeling effort could be completed.

After 4 quarters of ground water monitoring and supplemental site characterization a sufficient database had been assembled to perform the MNA modeling assessment of the two remaining plumes. One of the plumes was observed to be shrinking, although the center of mass was moving toward compliance wells. However, the modeling simulations indicated that over a period of 5 – 7 years the center of mass would continue to biodegrade to groundwater standards for benzene before reaching sentinel wells.

Supplemental site characterization revealed NAPL product averaging 0.1 foot in thickness in the source area of the third and final site. Using the historical and supplemental site characterization data, an evaluation of the potential for MNA to remediate the site is being performed. As part of the MNA evaluation Pelorus is evaluating how much source reduction will be required to ensure that MNA will meet remedial objectives within a 3, 10 and 15 year time frame.

The remedial technology recommended by Pelorus for the source area is, In situ chemical oxidation using hydrogen peroxide and the Fenton Reagent process. Pelorus has developed a proprietary formulation of catalyst stabilizers and rate enhancers that increase the over control and efficiency of the process. Application of this process to the source area will be targeted to achieve the desired mass reduction necessary for MNA to meet NJDEP regulatory requirements.

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