Tests show ‘consistent’ drop in benzene levels at Parachute leak site
Benzene levels in Parachute Creek have shown consistent reductions in recent days, according to test results.
The reductions come as Williams continues to work with state regulators to strip the carcinogen from groundwater before it reaches the creek, and to also remove benzene from the creek. The work follows the leaking this winter of what Williams estimates was about 10,000 gallons of natural gas liquids into soil and groundwater from a pipeline leaving its gas processing plant northwest of Parachute.
The leak resulted in high benzene levels in groundwater, and benzene in the creek that at one point barely topped the state drinking water standard of 5 parts per billion, although that standard doesn’t apply to the creek. The Colorado Department of Public Health and Environment said Tuesday the high daily measurement in the creek had fallen from 4.4 ppb on Thursday to 2.6 ppb on Sunday. Williams said it was 2.2 ppb on Monday.
That measurement site is about 1,300 linear feet downstream of the approximate spill location. Starting on Friday, a test site 2,158 feet downstream has no longer shown the presence of the substance, after having consistently tested positive. Likewise, Williams reported on Monday a site 1,643 feet downstream also tested negative.
Williams has been using aeration and pumping hydrocarbons from wells to help remove benzene and other contaminants. Newly installed vertical air sparge wells to treat groundwater benzene near the benzene’s point of entry into the creek went into operation Friday.
CDPHE said the domestic well of Howard Orona, who lives near the creek downstream of the leak site, again has tested negative for benzene.