Benzene levels as much as 800 times more than the federal drinking water standard have been found in shallow groundwater in a monitoring well just 10 feet from the banks of Parachute Creek at the site of a liquid hydrocarbon leak.
However, Todd Hartman, spokesman for the state Department of Natural Resources, said Tuesday testing of the creek water continues to show no signs of contamination from the leak.
Sampling results from the newly completed well shows benzene levels of 1,900 to 4,100 parts per billion. The Environmental Protection Agency’s maximum allowable level for benzene, a carcinogen, in drinking water is 5 ppb.
Readings from three other wells farther from the creek and closer to the contamination site have shown readings ranging from 5,800 ppb to 18,000 ppb.
The highest reading is near a recovery trench dug as part of the leak cleanup. That trench, and the area around an above-ground valve set for a 4-inch-diameter natural gas liquids line from Williams’ nearby gas processing plant, are being investigated as possible sources of what investigators think may have been historic releases of hydrocarbons. No active leak sources have yet been found.