Sinkhole turns out to be old mine shaft
July 11, 2008
A state investigator said this week a sinkhole-like depression discovered off the Rail Trail is at the surface of a historic mine shaft, a scenario that seemed plausible soon after the depression was discovered.
Louis Amodt, a state geologist with the state Division of Oil, Gas & Mining, visited the site on Wednesday and said the shaft had been sealed with clay and dirt years ago. The shaft’s depth was not immediately known.
The depression measures about 8 feet by 10 feet. Debris inside near the surface prevents investigators from estimating the shaft’s depth, Amodt said.
He said there is not a danger of the ground near the opening collapsing into the shaft. Amodt estimates the shaft is at least 50 years old.
Park City was founded in the 19th century as a silver-mining outpost, and mining was the dominant industry through the middle of the 20th century. Tourism and skiing then emerged to dominate the economy, but underground mining-era shafts and tunnels remain.
Water eroded the clay and dirt seal over years, and the seal failed, Amodt said. Once the seal gave way, a pond on the land emptied into the shaft.
Recommended Stories For You
"It looks like there was a pond here. It drained the pond," he said, adding, "It’s like pulling the plug out of the bath tub."
It was unclear whether the land where the pond was situated is a federally designated wetland.
The water may have traveled through the mine shaft and drained into the Jordanelle Reservoir east of Park City, Amodt said.
The shaft is near a Rail Trail bridge designated Bridge #1, and it is located just east of Wyatt Earp Way. The authorities have cordoned off the site with tape and ‘Keep out’ signs.
The historic mining industry was centered in the mountains south of Old Town, and there are numerous relics from the era that remain standing in places like Empire Canyon.
But mining activity stretched to other places in Park City, including to points near the Rail Trail, according to Hal Compton, a historian with extensive knowledge of Park City’s mining industry. Compton said the Silver King Extension mine was once situated near the location where the shaft was found.
Compton, who works with the Park City Historical Society and Museum, said silver, lead and gold was mined from ground near the Rail Trail. He said the mining there roughly occurred in the first half of the 20th century.
Prospectors of the era found outcroppings — described as a massive rock pieces that the miners followed as they searched for underground strikes — along what became the S.R. 248 entryway. The state highway follows the Rail Trail route into Park City from the east.
"They were looking for precious metals anywhere," Compton said.