PSA - Groundwater Remedy and Quarterly Sampling Plan - Oliver Industrial Park - Hull and Assoc.

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Hull & Associates Inc. Page 15 APPENDIX 3: TECHNOLOGY DISCUSSION The options available for a cost-effective and reliable technology to treat chlorinated hydrocarbon contaminants such as tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2- dichlorethene (cis-1,2-DCE), and carbon tetrachloride in groundwater have in recent years moved away from traditional pump -and -treat processes, especially in cases where: • NAPL, micro -emulsions or high concentration adsorbed materials are present leading to high dissolved phase concentrations. • Access to groundwater is restricted by surface structures or uses. • Local restrictions forbid the implementation of other available technologies such as air sparging or natural attenuation. • Pump and Treat technologies have been applied, but have reached asymptotic removal rates. • Contamination is extensive and concentrations are too high for risk based closure but otherwise relatively low (typically 100-7500 ppb). • The migration of dissolved Chlorinated Aliphatic Compounds (CAHs) across property boundaries or into adjacent surface water presents a long-term remediation requirement. • The vertical migration of free phase CAHs (DNAPL) into underlying drinking water aquifers is a concern. The environmental chemistry of a site in part determines the rate of biodegradation of chlorinated solvents at that site. The initial metabolism of chlorinated solvents such as chloroethenes and chloroethanes in ground water usually involves a biochemical process described as sequential reductive dechlorination. The occurrence of different types and concentrations of electron donors such as native organic matter, and electron acceptors such as oxygen and chlorinated solvents, determines to a large degree the extent to which reductive dechlorination occurs during the natural attenuation of a site. To accelerate the natural processes, ZVI and enhanced microbial dechlorination processes are proposed to be utilized at the site. The utilization of coenzymes, oxygen scavengers and nutrients insures that little or no lag phase in the process is experienced and that the most efficient pathways may be utilized. Program Elements Nutrient: Critical to the sustained microbial activity and general microbial health is sufficient bio available nutrient. IET has incorporated nitrogen and o-POa into the remedial program such that organelle and ATP-ADP formation is not limited throughout the microbial respiratory process.