This article was published on: 08/1/15 12:00 AM
Membrane plant to begin running this fall
By Tyler Leeds / The Bulletin
The city of Bend has decided losing access to Tumalo Falls this summer is a fair price to pay for clean and tasty drinking water. Luckily for hiker and utility manager alike, the wait is almost over.
Crews are currently installing a pipe under the bridge that spans Tumalo Creek downstream of the famous sight. Work should be done and the falls reopened in the next couple of weeks, city officials say.
The pipe, which will carry drinking water to Bend, has been under construction since March 2014, though a lawsuit filed by environmental groups delayed the project. The city contends the pipe is needed to replace its aging predecessor, but Central Oregon LandWatch argued the U.S. Forest Service shouldn’t have approved a permit until impacts on water flow and fish were more thoroughly vetted. In December, a federal judge sided with the city, though the parties are now meeting in mediation to possibly stave off an appeal headed to the Ninth Circuit Court of Appeals.
Despite the legal pause this past winter, Tom Hickmann, the city’s director of engineering and infrastructure planning, says construction has been quicker than anticipated, in large part because crews have encountered less hard rock while digging than planned for. The pipe is buried about 4 or 5 feet beneath the ground, deep enough to escape any issues with frost. Made mostly of steel and with an interior diameter of 28 inches, the pipe follows the road from a new, under-construction filtration plant to Tumalo Falls, where it’s currently being laid in a trench under Tumalo Creek.
Burying a pipe under a creek is as tricky as it sounds. To get the job done, the city has funneled the creek into a series of large tubes that take it over a trench crews are excavating for the pipe. When water rushes out of the tubes downstream of the trench, it crashes into a concrete barrier meant to return the creek’s flow to its normal pace. The city was hoping to build a new bridge and hook the pipe on the underside, but the Forest Service vetoed that idea.
Hickmann says access to the falls was closed in June because hikers were less than courteous to construction crews and drivers ignored closed road signs. Initially, he said, the city hoped to keep the area open. However, the creek crossing and another section above the falls should be done “in a few weeks,” Hickmann said, meaning access will be restored.
The pipe is only one part of the $70 million drinking water project. Construction crews are still busy at the membrane filtration plant, which is located on the north side of Skyliners Road. The 15,000-square-foot facility will house a system that physically filters water through narrow tubes containing synthetic fibers. While controversial due to its cost, this system will be able to operate even if a wildfire dumps ash into the creek, something cheaper options considered cannot do.
Currently, the city only treats its drinking water with chlorine, a method federal regulations rate as being too lax. The new plant will bring the city into compliance, however, it will also bring new complications. For example, in case the plant needs to be shut off, the city has dug a giant pit next to the plant big enough to hold the entire volume of water the pipe can carry.
“This plant is getting very close,” Hickmann said. “We’ll start going through the start-up procedures next month, flushing the system and then we’ll start getting into learning how to run the plant this fall. We need a period where we just really learn how to run all the various systems and the details and nuances of it.”
Membrane-treated water should be coming through faucets later this fall, Hickmann added.
— Reporter: 541-633-2160, tleeds@bendbulletin.com