The Environmental Corner
By: John C. Bird, P.G., Vice President of EnviroForensics
The City of Modesto, California, began monitoring ground water in September 1984 to test 25 percent of its municipal water supply, as required by California Assembly Bill 1803. Of the 24 wells tested, 12 wells were found to be contaminated. Municipal Supply Well #11 was found to be contaminated with 16.7 parts per billion (ppb) of perchloroethylene (PCE); the State Maximum contamination Level is 5 ppb. The well was taken out of service. The City obtains all its drinking water from wells. An estimated 142,000 people obtain drinking water from Modesto municipal wells within 3 miles of the site. The California Department of Health Services (CDHS) and the Stanislaus County Environmental Health Department have identified Halford’s Cleaners, which is less than 0.5 mile upgradient of Municipal Supply Well #11, as a likely source of the PCE contamination. These agencies found up to 176,000 ppb of PCE in soil at Halford’s where a buried storage tank was being excavated and determined that Halford’s discharge to the sewer was contaminated. CDHS also found 84.6 ppb of PCE in a private well adjacent to Halford’s. Not long after, the United States Environmental Protection Agency (US EPA) took over the investigation and cleanup under the Superfund Program. This individual site is currently being remediated under S EPA control. The Halford’s Cleaners site was just the tip of the iceberg in Modesto. Continue reading “The Road Goes On Forever And The Trial Never Ends”