The end is in sight for Avista Utilities' $5 million natural gas pipeline upgrade and extension.

The roadblocks, detours, flaggers and day-long vibrations associated with the six-month project are nearing completion in east Medford. The final piece of the pipe project involves welding sections together at the corner of Spring Street and Pierce Road, an elbow-shaped turn near Dunbar Farms.

Avista Utilities spokesman Steve Vincent said paving over the torn-up streets will begin as early as Monday, starting at the corner of Hillcrest Road and Pierce Road and working toward Spring and Springbrook.

"It could take a week, depending on weather," Vincent said. "If it's under 45 degrees, the asphalt just doesn't cure right. But looking at weather forecasts, I'm seeing 62 degrees by next Wednesday."

Boring six days a week, 10 hours a day for three months, Brotherton Pipeline crews bore 2,000 feet in three months along Spring Street. In contrast, the Gold Hill firm has drilled 12,000 feet in a single week in easier conditions, Vincent said.

"I've heard secondhand from some of the employees that they've never seen the kind of rock they encountered on Spring Street," Vincent said. "And they've worked all over the country and places like Japan and Peru."

During the project, Vincent discovered east Medford hills have been a tough nut to crack more than once. Crews had to blast their way through some of the terrain when city water lines were built along Spring Street, and ground near Rogue Valley Country Club proved to be particularly resistant.

"In the area around Black Oak Drive and Hillcrest, when the water and sewer lines were put in, they had to use dynamite," Vincent said. "One person told me that his parents made him climb up on the roof to remove rocks, and retrieve them from the swimming pool."

Avista snaked a 10-inch pipeline from the Delta Waters Road area, south to Spring Street, east to Pierce Road, west to Hillcrest Road to the Hillcrest Orchard area, connecting a line from White City to North Phoenix Road in Medford. Brotherton Pipeline placed pipes as much as 50 feet beneath the surface as they put the final vertebrae of its eastside backbone together.

That provides the utility with major distribution lines on both sides of Medford for the first time. It also provides redundancy in the system by tying together two natural gas distribution lines, one coming from the north and one coming from the east.

The work was necessitated by growth in the Medford area, Vincent said.

"This line is necessary for the current demands of east Medford," he said. "This is a once in a 50-year kind of project."

Because the project took longer than expected, it's likely the cost will be higher than anticipated, but Vincent said contingencies were built into the contract.

"We haven't got all those invoices in, so we don't have an exact number," he said. "It could take a couple more weeks before we know the full extent."

Avista is required by city ordinance to repave the roads.

"Utilities anticipate three, four or five decades down the line," he said. "Part of that is chasing down business, and that's the cost of doing business."

On the bright side, Vincent said, local Brotherton workers who might have been holed up in a motel on a job elsewhere got to sleep in their own beds.

"They got to go home every night and not be on a boring rig somewhere else in the country," he said.

Natural gas was first piped into the Rogue Valley in 1963 when a pipe paralleled Interstate 5 from British Columbia. Avista's local predecessor extended a line into the Bear Creek drainage, working its way through the west side of the freeway.

Decades later, a pipe from the Klamath Basin brought gas over the Cascades to a point near 2Hawk Winery on North Phoenix Road. In recent years, the gas line was extended north along North Phoenix Road. Another line from White City traced Crater Lake Highway to Delta Waters Road.

When the project extended beyond its announced duration, Avista representatives posted signs thanking drivers and neighbors for their patience and walked door to door to talk with affected residents.

"It turned out to take a lot longer than we projected," Vincent said. "We are really close to completion."

 Reach reporter Greg Stiles at 541-776-4463 or business@mailtribune.com. Follow him on Twitter at www.twitter.com/GregMTBusiness and on Facebook at www.facebook.com/greg.stiles.31.