Document text
Crews drill beneath Rogue to install Shady Cove sewer pipe Technology allows city to take shortest, safest route to treatment plant By Melissa Martin of the Mail Tribune Kurt Bickle of Armadillo Underground, Inc., guides a boring bit 40 feet beneath the Rogue River to pave the way for Shady Cove's new sewer line. SHADY COVE -- It might be a familiar site in the oil fields of Texas, but in Southern Oregon, drilling crews are making history as they bore a horizontal path to lay a sewer pipe beneath the Rogue River. Crews from Armadillo Underground Inc. have set up generators, computers and a compass on the east side of the Rogue to guide a directional drill bit 40 feet underground to the opposite riverbank. After they bore 600 feet across (and beneath) the river, they will run an 8-inch polyethylene pipe that will carry sewage from homes and businesses in east Shady Cove to the treatment plant about two miles away on the west side of the river. "This is technology that comes from the oil-field industry," said Lyle Schellenberg, president of the Salem company that specializes in horizontal drilling beneath the earth's surface. "They used this technology to drill underneath the next guy's property to steal his oil," he said jokingly. Shady Cove won't be stealing any oil, but it hopes to save money by sending the sewer main through the shortest and safest route from the pump station to the treatment plant, said Jerry L'Estrange, city administrator. Currently, the city's overburdened sewer pipe is stretched across the Highway 62 bridge. "This is a much more environmentally friendly way to lay sewer pipe," said David Bennett of Bennett-Staheli Engineers, the directional drilling consultant working with Shady Cove and Corolla Engineers, the project's primary designer. Cities that used to trench across a river to lay pipes are now drilling beneath rivers, even major rivers such as the Mississippi and the Missouri, Bennett said. However, boring through clay soils in the Southeast and Midwest is not as complicated as drilling through Northwest volcanic rock. "This is not the simplest river crossing," Bennett said. "The rock conditions alternate between hard, strong rock and weak, decaying rock." At the drilling site off of Maple Street in Shady Cove, Armadillo Underground crews depend on the brains of the operation, Inrock Guidance Systems Inc. of Houston. Navigator Ken Thibodeaux sits in his vehicle with a laptop computer and a two-way radio that he uses to communicate with the drill operator. Thibodeaux laid out a magnetic grid on top of the ground before the drilling began. It's like a giant compass, he said, tracking the underground guide wires in front of the drill head and sending signals to his portable computer. "It's pretty much like flying an airplane," Thibodeaux said. While he's talking, he plots the drill's movements on a graph. This navigating job -- which requires a working knowledge of calculus and trigonometry -- has taken him around the world, including Canada, Brazil and Colombia. Besides the steering tool, the drill has another companion underground -- Bentonite, a natural-occurring clay mined in Wyoming. Bentonite has the ability to suspend to other particles, Schellenberg said. "It floats the cuttings out of the hole," he said. The brown Bentonite fluid flows out of the ground into a backhoe-built pit where it's piped through a separating plant that removes the rock cuttings from the drilling slurry, Schellenberg explained. It's then piped back into the drilled hole. If the drilling is successful, crews will change sides of the river next week and send a reaming bit back through the pilot hole to make it large enough to hold the 8-inch sewer pipe. Then they will pull the fused, high-density, polyethylene pipe through the hole. "By pulling it through all at one time, there will be no joints in the pipe underneath the river," Schellenberg said. This may be Schellenberg's first drilling beneath the Rogue River, but he's tapped the ground throughout the Pacific Northwest. His company laid a pipe with communication wires underneath the Molalla River and a natural gas pipeline beneath the Pudding River, both near Canby. His crews also sent a natural gas line beneath Spooner Creek at Lincoln City. "We just bid a job to drill beneath the Pacific Ocean to send electrical cables to an island off the coast of Washington state," he said. Shady Cove is boring beneath the Rogue River as part of a $625,000 rehabilitation of its sewer system, which is too small to handle the city's growing population. Ground water is also entering the sewer system and causing problems, the city's public works director said. The project is being funded by state lottery grants and a $1 a month increase on residential sewer bills. Mail Tribune Copyright � The Mail Tribune 1999, Medford, Oregon USA