Groundwater contamination discovered seven years ago near a former Nike missile site in the Deep Creek area continues, but its source remains a mystery, the Environmental Protection Agency said Monday.
In a letter updating the status of the contamination site, the agency said wells along Euclid Road between North Woods and Richie roads, west of Airway Heights, continue to show contamination with the solvent trichloroethylene, or TCE.
The letter from Renee Dagseth, EPA community involvement coordinator, to the Spokane Association of Realtors and the Washington State Ground Water Association advises property owners to avoid drilling wells within the boundaries of the contaminated area.
The chemical, once commonly used as an engine degreaser by the U.S. military, is a carcinogen. Drinking water contaminated even with small amounts of TCE for long periods may cause liver and kidney damage, impaired immune system function and impaired fetal development in pregnant women.
The EPA says that despite an extensive investigation, it has not been able to identify the source of TCE. Wells in the area draw from fractured basalts, which make it difficult to determine the precise boundaries of the contamination.
The agency advised property owners planning to install wells outside the contamination boundaries to test their water for TCE.
The chemical was first discovered in the Deep Creek area late in 2004 during an EPA assessment of the former Air Force Nike Missile Battery 87, which was in operation in the late 1950s and early 1960s.
After confirming the presence of TCE, the EPA tested for two chemicals associated with solid rocket fuel: perchlorate, known to disrupt thyroid function, and N-nitrosodimethylamine, or NDMA, a probable carcinogen. Both were found at very low levels in numerous wells in the area.
Nevertheless, a U.S. Army Corps of Engineers report released in 2007 found no evidence linking the missile battery to the groundwater contamination. The corps cannot spend Defense Department funds on environmental spills without first establishing a clear link to a military source.
The Spokane Health District has applied for a grant from the Washington Department of Ecology to continue monitoring wells in the area.