Build that wall: EPA races to block gas leaking into Popo Agie

Storm clouds build as workers excavate the east bank of the Middle Fork of the Popo Agie River where gasoline was found seeping into the stream. The EPA plans to build a concrete cut-off wall and recovery wells at the site to keep future contaminants from reaching the river. A fire and a spring storm have hampered efforts as workers race to complete the job before spring runoff and rising groundwater make matters worse. (Elyse Guarino / WyoFile)

April 12, 2019 by Matthew Copeland, WyoFile

An object of heated public debate when it was approved for construction in 2007, a Lander gas station is once again fueling community consternation — and possibly a calamity for the beloved stretch of river that runs through town.

The Lander Fire Department, responding to reports of a strong gasoline odor, discovered an oily sheen on the Middle Fork of the Popo Agie River near its Main Street underpass immediately downstream of a Maverick gas station on April 2, according to EPA reports.

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Volunteer firefighters deployed rigid booms to contain the contaminants and maintained a hazardous materials perimeter until a response team from the EPA arrived from Denver on Apr. 4. As a navigable waterway, active threats to the Middle Fork fall under EPA jurisdiction.

“I know it sounds like a line but it’s true: Our job first and foremost is to keep you [the public] safe,” said Craig Giggleman, on-scene coordinator for the federal agency. Initially, that means isolating the source of contamination and halting its flow: “First thing is to stop the bleeding.”

Nine days out from the discovery they’re still trying to do just that. Workers have staunched the flow into the river with a perimeter of temporary barriers — rigid booms and a super-sack sandbag embankment — but have yet to reach the source of two identified seeps. Their efforts have been slowed by a heavy spring snowstorm and, more alarmingly, a brief fire on site.

“We retrograded pretty darn quick,” Giggleman said of his team’s retreat when a spark ignited gas-saturated soils. Understanding that the alluvium and cobble makeup of the ground could contain interstitial gaps, his primary concern was that the flames might follow the seeps through the earth and potentially even back to the source.

“If that had happened I wouldn’t be here talking with you,” he said in a black humor nod to what may have happened if flames found a large quantity of gasoline. The Lander Volunteer Fire Department responded in under five minutes, he said, and extinguished the blaze with foam.

Shortly thereafter Giggleman and his team were back to work, excavating the east bank with the goal of isolating the origins of the seeps and making room for a semi-permanent concrete cut-off wall designed to block the contaminants from the river. They will also install two recovery wells behind the wall to collect and monitor the seepage.

The EPA hopes to start construction of the wall as early as Thursday, April 11, Giggleman said. Once poured the concrete structure will need at least 5 days to cure.

The Associated Press reported on Saturday that the Wyoming Department of Environmental Quality has determined the gas is originating from the nearby Maverick.

The agency said Maverick overfilled its underground tanks, which caused the fuel to migrate into the river. The department filed a notice of violation on Friday against the store for failing to make repairs that prevent overfilling, according to the AP.

Speed is of the essence. Heavy spring run-off will fill the river with meltwater at some unknown point in the near future, making continued work more difficult if not impossible.

“There’s a [U.S. Geological Service] river gauge about five miles that way’” Giggleman said, pointing upstream. “You’d better believe we’re checking it about every 30 minutes.”

Maverick did not respond to requests for comment by press time.

Twelve years ago, when the public became aware of the planned development, concerned residents questioned the wisdom of siting a 16-pump gas station immediately adjacent to the river. Proponents and permitters at the time countered that, having been home to a service station previously, the lot was appropriate — better to use an already compromised location than to create fresh impacts elsewhere.

Lander gets its drinking water from the Popo Agie, well upstream of the point of contamination. Hudson, Riverton, numerous irrigators and miles of river prized by hunters and anglers lie downstream.

Wyoming does not have a set-back law requiring that gas stations or underground storage tanks be positioned a minimum distance from waterways.

This article was originally published by WyoFile and is republished here with permission. WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.

This story has been updated with Associated Press reports.