Some contaminant levels drop at Parachute plume | PostIndependent.com

Some contaminant levels drop at Parachute plume

John Colson
Post Independent staff

PARACHUTE — The ongoing cleanup of natural-gas liquids near Parachute Creek continues this week, but state officials report that the levels of at least one potentially hazardous contaminant are diminishing.

In a report released on Monday, spokesman Mark Salley of the Colorado Department of Public Health and Environment indicated that daily water samples taken from the creek have shown “a shrinking area of benzene contamination in (the creek’s) surface water.”

According to the report, one sampling location, near where benzene is believed to be entering the creek from a plume of contaminated soil, showed a level of 2.1 parts per billion (ppb) of benzene in the water. Earlier tests had showed benzene in the creek itself at levels up to 5.3 ppb.

Benzene, a carcinogenic compound commonly associated with oil and gas drilling activities, at one time showed up in the groundwater near the spill location at levels of up to 18,000 ppb.

The state’s drinking-water standard for human consumption is 5 ppb.

Because Parachute Creek is not classified as a source of drinking water, though numerous domestic wells exist on ranch properties close to the creek, the contamination standard applied to the creek is one for protection of aquatic life forms, at 5,300 ppb.

According to Salley’s update on the conditions at the spill site, which is about 4 miles north of the Town of Parachute, pumps are at work removing hydrocarbons from the surface of ground water in a number of monitoring wells. Salley reported that approximately 60 gallons a day of “floating liquid hydrocarbons” are being collected at the site, although he did not identify which compounds were being collected.

In addition to scooping up the contamination, the company has installed a “groundwater aeration trench” that also is designed to capture the hydrocarbon compounds believed to be floating on the surface of groundwater.

Salley also reported that a “comprehensive groundwater sampling program” was conducted last week, which included samples taken from 27 monitoring points in and around the area of the leak.

Results from that sampling program will not be available for two weeks, Salley reported.

One new development reported by Salley is a plan to install pipelines to transfer contaminated ground water to a “ground water treatment system,” although use of the pipelines and treatment system is not expected to get under way until mid-June.

Williams also conducted a “pilot test” of a high-tech instrument to measure the spread of the underground plume of hydrocarbons. Results from the survey conducted using the hand-held instrument also were not available immediately.

jcolson@postindependent.com


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