Tetrachloroethene (PCE) and trichloroethene (TCE) were present at concentrations that suggested the presence of nonaqueous-phase liquid (NAPL) in both vadose zone soil and groundwater at a brownfield site with significant redevelopment value. Investigation and remediation has been implemented in phases as cleanup funding is secured, and all efforts aim to maximize the value of every dollar spent. Based on the conclusions of an Analysis of Brownfields Cleanup Alternatives (ABCA), remedial technologies were selected to first target the area of highest impacts: soil vapor extraction (SVE) and in situ chemical reduction (ISCR) with enhanced bioremediation by injection of carbon substrates with zero-valent iron (ZVI). Multiple reductive additives were injected to achieve a cost-effective remedy by selecting the required strength amendment for different concentrations, and including two different ZVI amendments as well as sodium lactate. Fourteen months after startup, SVE has resulted in removal of over 1,390 kilograms (3,060 pounds) of chlorinated VOCs. Groundwater concentrations of PCE and TCE have been reduced by 80 percent to >99 percent. Dehalococcoides cell counts have increased more than three orders of magnitude from baseline, and concentrations of daughter products are also trending downward.
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