Top Stop begins remediation procedures
By John Hales
8-29-07

GUNNISON—The large, underground fuel tanks have been removed, and a remediation system has been put in place, but the cleanup of a gas leak that shut down part of Gunnison’s Main Street for a day and shut Gunnison Top Stop’s doors—probably for good—could take years.
Between Monday and Wednesday last week, crews from Wasatch Environmental, a consulting firm that contracts with Top Stop’s parent company, Wind River Petroleum, took out the three gas tanks that contained the store’s gasoline, finding in the process a nickel- to quarter-sized hole blamed for the leak.
Later in the week, they began installing a remediation system that will literally suck the spilled gas out of the soil, according to Wasatch Environmental engineer Les Pennington.
The system was scheduled to begin its work this week pending the delivery of a component of the system due in from another completed project in Castle Dale, Pennington said.
After Aug. 10, when officials evacuated businesses along Main Street for one block south of Top Stop and called in Sanpete County hazmat crews because of the gas leak, Pennington and others examined the nearby area to ascertain the extent of the leak.
“From exploration, we discovered contaminated soil along the sidewalk,” Pennington said.
Wanting, therefore, to get the remediation system as close to buildings as possible, crews cut a trench—in which to put the remediation system—down the center of the sidewalk on the east side of Main Street between Center Street and 100 South.
The system is called a soil vapor-extraction system, or SVE, and Pennington explained its operation.
“Basically, we put in slotted PVC pipe down in the trench, about nine feet deep, surrounded by gravel,” he said.
“We then seal off the top of the trench with flow-fill concrete (that’s really runny or ‘lean’ concrete) that hardens in about a day.”
One end of the pipe sticks out of the ground at one point. “Then we put a vacuum on the end of the pipe,” Pennington said. “It draws out the vapors, and that gives the vapor a place to go.”
But wouldn’t that simply trade soil contamination for air contamination?
Pennington said no.
“We’re allowed to emit a certain amount out into the atmosphere. We measure the concentration of gas from the air flow, and if we exceed emission standards then we’ll treat or filter that air stream.”
Pennington said the system could remain in place indefinitely, even after its work is done. “There’s no reason to remove it. It could be abandoned and the PVC pumped full of grout.”
Asked how long the cleanup would take, Pennington said it could take several years.
“Because of the buildings in the area, we’re limited in our options,” he said.
Pennington said that the actual amount of fuel lost due to the leak is still being evaluated by the Utah Division of Environmental Response and Remediation, a branch of the Department of Environmental Quality.
Based on statements from several unofficial sources, that amount could range from 12,000 gallons to more than 22,000 gallons.