Over the River and Through the Woods ...

Bend, Ore.’s, Bridge Creek pipeline project aims to replace 10 miles of water transmission mains passing through the Deschutes National Forest.
Over the River and Through the Woods ...
Heidi Lansdowne, principal engineer and project manager in the Public Works Department for the City of Bend, poses for a portrait at the worksite of the Bridge Creek pipeline replacement project along Skyliners Road in Bend, Ore. (Photos by Joe Kline)

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The City of Bend, Ore., is currently in the middle of the Bridge Creek pipeline project – literally. After months of legal challenges, the city’s Engineering & Infrastructure Planning Department has begun work on the central 8-mile section of a 10-mile, $24 million pipeline project designed to transport mountain water downhill from Bridge Creek in the west through the Deschutes National Forest.

Bend is located roughly in the center of Oregon and its population is approaching 80,000, an increase of almost 50 percent in a little more than a decade. The water project will replace critical end-of-life infrastructure that dates back 90 years.

The original water supply was privately delivered and derived from the Deschutes River. However, by the 1920s state authorities declared the source unfit for human consumption due to the effect of the local lumber industry.

The city purchased the system in 1924 and settled on a new, high-quality water source – Bridge Creek. A new pipeline would convey water downhill by gravity.

“The initial system became operational in 1926 and consisted of two storage facilities and a 12-inch pipeline close to 14 miles in length, because it was a lot farther into town than today,” says Tom Hickmann, director of the Engineering & Infrastructure Planning Department. “The town grew and a second 12-inch line was constructed in 1955.”

In 1968, the city purchased two surface wells from logging companies and invested in newly-developed deep well technology to access the area’s robust aquifer 800 feet below. While Bridge Creek provided year-round water, the wells supplemented that source during summer. The city currently operates 23 wells.

Early efforts unsuccessful

“By 1982, the Bridge Creek pipeline had deteriorated and there was an effort to upgrade the mains with 24-inch ductile iron, but nobody thought about the hydraulic grade lines,” says Hickmann. “With the best of intentions, they replaced a few sticks near the head of the system instead of at the bottom and, when demand was low, the system overflowed and would have become a geyser if they had continued. At that point, there was no political will to spend more money on it.”

When the Environmental Protection Agency’s Long Term 2 Enhanced Surface Water Treatment Rule was adopted in 2006, the city took a fresh look at its water sources and infrastructure.

“The situation with the Bridge Creek pipeline was serious and we began the process of securing a quality year-round water supply for the city,” says Hickmann.

While the Bridge Creek pipeline approached the end of its life, the rest of Bend’s water system, built largely during the 1950s and 1960s, remained robust. The system is about 80 percent ductile iron, ranging from 2 to 36 inches in diameter, with the majority of lines measuring 8 inches. Two private water systems operate within the city.

Pipe breakages are minimal, usually the result of improper backfilling and truck loading on the few cast-iron and galvanized lines that are in the system.

One exception is a formerly private water system condemned and assumed by the city in 2002.

“It’s thin-walled PVC with glued joints,” says Hickmann. “It’s very difficult to maintain and run. We’re trying to fix it incrementally, and we’ve had some interest in selling that system back to a private owner.”

The system is 100 percent GIS mapped, with data fed into the city’s hydraulic modeling system using INFOR, its asset management program. Leak monitoring is achieved through the use of an automated meter information system.

An in-house department performs repair and maintenance on both sewer and water systems on jobs valued less than $120,000. That includes shortline repairs of about 100 feet. At the utility’s disposal are two vans outfitted with CUES CCTV equipment and five Vactor 2100 hydroexcavators and combination sewer cleaning trucks.

Replacement favored

“Given all of the information on the water system, and our wells, we used Optimatics software [see sidebar] to determine the most cost-effective course of action to secure the city’s water supply,” Hickmann says. “The analysis favored replacement of the Bridge Creek lines.”

Heidi Lansdowne, principal engineer and project manager on the Bridge Creek project for the City of Bend, describes the system as elegantly simple.

“There’s a small diversion structure on Bridge Creek, with a caretaker’s house and intake structure built in 1926 that’s still there,” she says. “There are screens to filter out twigs and leaves and the water travels by gravity through 1,000 feet of elevation to a water treatment reservoir basin.”

Hard evidence of the pipeline’s advanced age has included sections of asphalt lining shed from the original steel pipe and found in system reservoirs.

“Also, some of the easements were not well-maintained so we have trees growing over and around the original pipes,” says Lansdowne.

The system’s new design includes improved screening at the pipe intake, including protection for aquatic species.

“The current system also operates at full flow 24/7,” says Lansdowne. “The new system will allow us to control flow, to only take water when we need it.”

A U.S. Forest Service environmental assessment (EA) limits the city’s water withdrawals to match what is currently withdrawn. The EA will also require extensive monitoring of stream flows, temperature and fisheries in Tumalo Creek, into which Bridge Creek flows.

The replacement pipe will have a nominal diameter of 30 inches and be constructed of three materials with different wall thicknesses, with the thickest located at the bottom of the system where hydraulic head is greatest.

“Over a distance of 10 miles, optimizing the pipe materials and wall thicknesses saved us considerably on pipe cost,” says Lansdowne.

The top 2 miles will specify high-density polyethylene (HDPE) and a short section of ductile iron pipe, while the lower 8 miles will be built using spiral welded steel pipe with cement mortar coating and lining.

Lawsuit delays construction

The city was ready to begin construction in 2012, with HDPE pipe already delivered to the site. However, a lawsuit brought by Central Oregon LandWatch and WaterWatch of Oregon delayed the project’s start, charging that the new system would harm the ecosystem of Tumalo Creek.

The initial design also offered a small hydroelectric facility that would dampen the hydraulic head near the treatment plant and provide electricity to the grid. Court challenges by the same groups also put that feature on hold.

However, U.S. District Judge Ann Aiken has given the city the go-ahead to install 8 miles of pipe in the paved Skyliners Road through the Deschutes National Forest, after the U.S. Forest Service (USFS) issued a permit for that portion of the project.

“The Forest Service received federal highway funding to reconstruct Skyliners Road, and this section of pipe – Phase 1 – runs entirely underneath it,” says Lansdowne. “We can complete Phase 1 of the project and save ratepayer dollars by coordinating the road repair from the pipeline and road reconstruction of both projects.”

The forest project requires significant environmental covenants during construction.

“The USFS Special Use permit to allow our construction requires us to protect wildlife ranging from raptors and owls to bats and bumble bees,” says Lansdowne. “Work began in March 2014 and if all goes well, we should be finished with this phase of construction by March 2015.”

While construction of the upper and lower segments of the pipe can only commence following the conclusion of the lawsuit, the city has calculated that moving forward on any section of the project is in the community’s best interest.

“The new screening system is not only better for the wildlife at Bridge and Tumalo creeks, but the project provides us with much-needed flow control that will help to maintain water levels in the creek,” says Hickmann. “We’re also eliminating the possibility of a rupture along the original pipe. We believe that completing this project is best not only for the citizens of Bend, but for the environment.”



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