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Geothermal effects mean park sewer lines anything but faithful When opened, fire hydrants may vent steam for minutes By MICHAEL MILSTEIN Gazette Wyoming Bureau YELLOWSTONE NATIONAL PARK - Strange things happen to sewer and water lines when the ground simmers at 200 degrees or more. Steam shoots out of fire hydrants. Grease bakes into cement-like layers on the inside of sewage lines. Pipes disintegrate. Flushed toilets fill with water hot enough to melt gaskets.
"This is definitely a different operating environment than at other developed areas in the park, or probably anywhere," says Tim Hudson, chief of maintenance in Yellowstone. Old Faithful was a different place in the 1950s, when many of today's sewer lines were installed. Parking lots wrapped in close formation around the geyser, laying atop ground heated by the same geological systems that drive Yellowstone's geysers and hot springs. Park workers at the time may not have realized the consequences of laying sewer and water lines through the same hot ground. "They just ran everything right up near the thermal features," Hudson said. "Right now sewage comes out of the (Old Faithful) Lodge and flows that way, towards the geyser," he says, pointing at Old Faithful. Hudson and Jeff Schelbach, who runs the sewage treatment plant at Old Faithful, quickly pry up a metal cover to reveal a grease trap intended to catch grease emerging from the Old Faithful Lodge kitchens as it cools and coagulates, keeping it out of the sewer lines. But the grease trap is undersized and the ground is hot, keeping the grease from coagulating, so that much of it escapes into the sewer. Following the sewer line, Hudson and Schelbach arrive at a manhole about 100 feet from the cone of Old Faithful. The ground temperature here runs hotter than 200 degrees, and when they open the manhole, a gush of steam billows out. A glance into the dark hole reveals popcorn-shaped clumps of grease and other unmentionables floating by in a line about eight feet down. "We get lots of grease - heavy grease, severe grease," Hudson says. "It bakes right on the inside of the tube." Pace Construction of Billings sent a tiny video camera down the sewer line and found that hardened grease had shrunk the diameter of the pipe from 8 inches to between 4 and 6 inches, making clogs in cooler points in the line more likely. Once, when crews dug up the line to remove a "blockage," as Hudson calls it, they found they could not stand in the ditch. "It would burn your soles right off," Schelbach said. Farther down the line, heat from a vent pipe rising from the underground sewer charred the interior of the Old Faithful Visitor Center. Simply put, the line is in a bad spot. "It's no good for us sewagewise, it's no good resourcewise - we shouldn't be there," Hudson says.
Also this year, Amfac Parks and Resorts, which operates Yellowstone's lodges, will install new, larger grease traps at both Old Faithful Lodge and Old Faithful Inn. Old Faithful last year was the site of two of Yellowstone Park's growing list of sewage spills: once when grease blocked a sewer line leading from Old Faithful Inn and sewage overflowed into a creek and again when grease clogged another line and sewage flowed into an abandoned septic tank and from there into the Firehole River. Park workers early this summer expanded the pump house, called a "lift station," that drives sewage to the treatment plant to include a 20,000-gallon backup holding tank and a backup, propane-powered generator to keep sewage from collecting in the tank during a power failure. Hudson, lifting a lid over the holding tank, picks up a garden rake and plunges it into a layer of grease about 5 inches thick floating atop the liquid sewage below. "Once the new grease traps are in, we shouldn't be seeing this here anymore," he said. Just up the road, behind Old Faithful Inn and Hamilton Stores' closest gift shop is another place where underground lines and geothermal heat butt heads. A water line installed about 20 years ago runs along the edge of what is known as the Myriad Group of geysers, where the ground is extremely hot, especially five feet down where the pipe lies. Shortly after the line was installed, crews opened a fire hydrant that draws water from the line, and the hydrant vented steam for 20 minutes before any water emerged. Water flowing from the "cold" water taps in the Hamilton Stores gift shop sometimes emerges very hot and has in rare cases melted the gaskets on toilets. "They don't use their hot water heater much," Hudson says. "They don't need to." While many people let their faucets drip during the winter to keep water moving through their pipe so it doesn't freeze in place, Yellowstone maintenance staff keeps water flowing through the lines so it doesn't boil in place. The practice is essential in the winter when the store doesn't operate and water would otherwise stand in the line until it boils and wastes about 30,000 gallons of water each day, Hudson says. The ground is not only hot, but also acidic, and eats away at metal lines, "so the pipe is usually gone in 15 or 20 years," he says. Before that happens, crews are installing a new, specially insulated water line within about three feet of the cooler surface of the ground in the hopes that the line itself will remain cooler. Raising the line, installing the new sewage conduit from Old Faithful Lodge and installing new grease traps will, altogether, cost about $1 million, which the National Park Service has funded separately from Yellowstone's normal annual budget. "Most people would think we're battling the cold, but we're really battling the heat," Hudson says. "It makes you come up with some unique solutions."
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