Williams officials said they have concluded that “a failed pressure gauge is the source of the hydrocarbon fluids” the company found last month near its Parachute Gas Plant. “The leak was stopped on Jan. 3, 2013 at 12:33 a.m. The gauge was part of valve set on a four-inch NGL pipeline belonging to Williams Partners.”

Based on the company’s evaluation of data from two flow meters on the NGL pipeline, the pressure gauge leak started Dec. 20. Using U.S. Environmental Protection Agency (EPA) testing standards, Williams said it estimates that 80% of the NGLs vaporized before entering the soil.

The incident in the area of Williams midstream operations came to light March 15. Since that time, 142 bbl of oil has been recovered, and the Colorado Oil and Gas Conservation Commission (OGCC) reported that there were also more than 2,000 barrels of water collected to help ensure that if some contaminated water was part of the leak it would be kept out of Parachute Creek (see Daily GPI, April 1).

OGCC also reported Wednesday that it obtained new information on groundwater samples from three new monitoring wells about 50 feet south of Parachute Creek that showed benzene concentrations between 51 and 450 parts-per-billion. “Those wells had been thought to have been unaffected based on preliminary field information reported on Tuesday,” an OGCC spokesperson said.

Williams report emphasized that laboratory analysis reports on water samples have indicated that Parachute Creek is unaffected by the hydrocarbons found in soils in the surrounding areas.

Williams reported the hydrocarbon discovery in the area to regulatory agencies March 8, and the OGCC on March 15 issued a “cease and desist” order requiring Williams to take all appropriate measures to prevent contamination of the creek. On March 18, the EPA issued an administrative order outlining required stabilization and mitigation actions required by Williams.

In its Wednesday report the state OGCC said new monitoring wells both to the south and east of the creek are now being planned.

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