Old oil, gas contamination probed in Thompson Divide

Authorities are investigating contamination involving what are believed to be historic leaks or spills from four oil and gas well pads in the Thompson Divide area southwest of Glenwood Springs.

The contamination relates to infrastructure owned by SourceGas LLC subsidiary Rocky Mountain Natural Gas. Its discovery comes amid controversy over efforts by companies to renew drilling in the Thompson Divide, which covers some 220,000 acres of mostly national forest and stretches roughly to McClure Pass.

The releases were discovered as part of an ongoing $10 million undertaking by SourceGas to enhance the safety and reliability of its Wolf Creek Natural Gas Storage Field above Sunlight Mountain Resort.

SourceGas uses the 9,254-acre field to store gas in depleted gas wells for use in serving the Roaring Fork and Eagle valleys in the winter. Many of the wells were drilled in the 1960s and were converted for storage in the 1970s.

According to a report on the Colorado Oil and Gas Conservation Commission website, SourceGas reported that on June 20 it discovered contamination after removing production equipment and a building surrounding it on a pad. The report said the exact volume of the release isn’t known but its source may have been removed.

The report said groundwater contamination occurred, with groundwater just 5 to 6 feet below the surface, and soil 
contamination was contained to the well pad.

On Friday, SourceGas issued a news release that also discussed the other cases of contamination.

“In each case, RMNG has immediately notified the appropriate state and federal agencies, instituted extensive sampling, and wherever needed is taking measures to remediate these sites,” SourceGas said.

One of the other instances involved discovery of a discolored seep at the downgradient toe of a well pad last year. SourceGas said low levels of hydrocarbons were found.

It said that at the direction of the Forest Service and Bureau of Land Management, it did more sampling at that location and two others with similar characteristics. Contaminants above regulatory thresholds were found at one of the other sites but not the other.

Bureau of Land Management spokesman David Boyd said 400 cubic feet of soil contaminated with hydrocarbons and glycol, which is used to dehydrate natural gas, was excavated last summer from one of the pads where a building and equipment had been removed.

SourceGas said sampling this summer downgradient from the pads, at a ditch running to Divide Creek three-quarters of a mile away, found no contamination.

Boyd said while further test results are still pending, all the contamination appears to involve “historic spills that are confined fairly close to the pad.”

With the possibility of renewed Thompson Divide drilling looming, Boyd said spills are always a possibility, but modern-day practices and equipment are a lot different and agencies impose measures to minimize risk.

The SourceGas upgrades include new concrete slabs designed to contain any spills, replacing wood buildings with metal ones to reduce fire risk, improving communications equipment to allow remote 24-hour monitoring, and adding a system to automatically shut in a well if a fire or leak is detected.

Peter Hart of the Wilderness Workshop in Carbondale, which opposes Thompson Divide drilling, said some advancements reduce impacts, “but there are also technological advancements that have occurred over the years that actually increase impacts associated with oil and gas development.”

These impacts result from things such as drilling deeper wells with long horizontal reaches, and boosting truck traffic to hydraulically fracture wells both initially and then repeatedly over many years, he said.

“Associated with all of that are air emissions and all the potential for human error associated with spills and everything else,” he said.


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