Lab Contaminated Tri-Cities' Water Samples
U.S. Environmental Protection Agency Region 5 said the results of some samples from the Midland, Saginaw and Bay City, Mich., water supply systems taken last July are faulty due to laboratory contamination.
EPA collected the samples in response to community questions about impacts to drinking water from contaminated sediment stirred up by U.S. Army Corps of Engineers' navigational dredging in the Saginaw River. Dioxins and furans are byproducts of historical industrial processes by the Midland-based Dow Chemical Co.
Test results showed low levels of furans in the samples; however, because the furans were also detected at similar concentrations in clean blank reference samples, scientists quickly realized these results were actually caused by lab contamination. Since the results are unusable, EPA contacted the cities to schedule a new round of sampling.
After reviewing the situation with SGS North America the company whose lab analyzed the results EPA confirmed the water samples were contaminated by furans in the lab equipment. SGS has since modified its equipment and processed a new, clean blank reference sample. This sample did not detect any furans.
"EPA has extensive quality control procedures in place to catch analytical problems and this case proves they are effective," said Acting Regional Administrator Bharat Mathur.
This past July 28-29, EPA contractors Weston Solutions collected samples from both the intakes and from treated water for the Saginaw, Midland and the Bay City water supply systems. The samples were then processed by Weston's subcontractor, SGS North America (Wilmington, N.C.), which operates a laboratory certified to analyze dioxin and furans. More sampling is planned for spring 2010, when USACE dredging is expected to resume.
The EPA water sampling tested for more than 120 other chemicals. The results for these other chemicals, analyzed at a different lab, were below EPA's maximum contaminant levels which ensure municipal drinking water supplies are safe. The complete report was updated Oct. 7.
The agency is forming a community advisory group for the Dow Superfund site. Applications are now available for membership and are due no later than Oct. 16.