Ground water contamination at five San Gabriel Valley sites is being assessed to ensure that leaks from underground chemical storage tanks do not reach drinking water supplies.
Most of the contaminated sites came to light when businesses applied to the county Department of Public Works for permits to discontinue use of the tanks, where gasoline, oil or cleaning solvents had been stored.
Preliminary testing has disclosed some leakage from tanks at all sites in El Monte, South El Monte, Walnut, the City of Industry and Rosemead, said Josh Workman of the Regional Water Quality Control Board. But the pollutants have not spread deep enough or far enough to reach drinking water stored in wells, he said.
Under Proposition 65, the toxic drinking water initiative passed in 1986, closure permits must include reports of possible leakage. The requests are referred to the water board, which recommends ways to clean up any contamination.
Cleanup costs must be paid by the businesses.