The Environmental Protection Agency is reviewing the potential hazards of transporting natural gas contaminated with extremely lethal concentrations of hydrogen sulfide through two Utah counties.
Concerns expressed by residents of Evanston, Wyo., prompted the EPA decision to examine an already-completed "hazard analysis" of the Wahsatch Gathering System pipeline, said Bill McMahan, a Bureau of Land Management environmental coordinator based in Rock Springs, Wyo.Union Pacific Resources plans to build the Wahsatch Gathering System, a 41-mile pipeline that will connect eight "sour gas" wells to a processing plant in Whitney Canyon, about 16 miles northeast of Evanston.
Sour gas is natural gas contaminated with hydrogen sulfide, which is hazardous to people, wildlife and livestock in even low concentrations. Once the hydrogen sulfide is removed, the gas can be burned as fuel in homes and businesses.
The sour gas that will be transported in the pipeline will have a hydrogen sulfide concentration of 15 percent, or 150,000 parts per million. A person exposed to sour gas with 700 parts hydrogen sulfide per million would die in less than two minutes, according to a Union Pacific Resources study.
The sour gas will be taken from seven wells in Wyoming and one in Summit County.
The Summit County well, located about 10 miles northeast of Coalville, will account for about half the total sour gas that will be processed at the Whitney Canyon plant.
The project, proposed by Amoco in 1983, received final approval in 1984. Amoco sold its interests to Union Pacific Resources, which is virtually certain to be allowed the same pipeline right-of-way, McMahan said. Union Pacific plans to begin pipeline construction in 1993.
An environmental study completed in 1984 shows a 95 percent chance of a "pipeline incident" and a 28 percent chance of a pipeline rupture over the 20-year life of the project, but it assumes the actual risk of exposure to people living in the area to be almost non-existent.
Evanston has grown since the 1984 study was completed. Three neighborhood meetings on the pipeline were held in June in subdivisions closest to the pipeline's path, and a fourth public meeting was held in Evanston City Hall.
"As can be expected, the primary concern expressed by the public was the risk associated with release of the sour gas," McMahan said.
The public wanted an independent review of a hazard analysis of the project. The EPA's report should be completed by the end of July, McMahan said.
About 18 miles of the project will run through Summit County, and approximately nine miles of line will run through Rich County.
Union Pacific Resources representatives in May met with officials in Summit and Rich counties.
The pipeline will cross the Utah-Wyoming line six times and will run under I-80, U-16 and the Union Pacific railroad line. The pipeline will also cross two sections of the Bear River in Wyoming and will pass through important wildlife habitat in the two states.