Rapid Reduction of VOCs Results in Site Closure
Subsurface investigations at a dry cleaning facility revealed elevated levels of PCE and other regulated daughter products. A remediation technology was needed that could cost-effectively reduce the contaminants to the Washington Department of Ecology’s (WDOE) cleanup levels. HRC was chosen for groundwater remediation due to its ability to provide a low cost solution for site restoration. A groundwater monitoring program was created to assess the efficacy of remediation. The results from this program indicate a significant reduction in all contaminants and provides convincing evidence that the application of HRC to a chlorinated solvent contaminated site results in successful site cleanup.
Total VOCs were reduced across the HRC grid area shortly after injection. Wells MW-1, MW-3, and MW-5 (Graph 2) were situated within the HRC grid area and thus represented the behavior of HRC. The results indicate a significant reduction in the concentration of PCE and its related daughter products. PCE and TCE were reduced by 99.8% and DCE was reduced by 94.5%. Similar results were displayed in all other wells affected by HRC. As a result of HRC treatment, PCE, TCE, and DCE levels have been reduced to 10 times below the federal standards. Although VC has dropped to 4 times below federal standards, contamination levels still exceed WDOE MCLs of 0.2 ug/L. This site is expected to gain regulatory closure in the near future once VC is reduced to 0.2 ug/L.