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By ADAM LAPIERRE

News staff writer

A crew armed with heavy machinery and hydraulic hammers went to work this week on the most destructive phase of the several-months-long Powerdale Dam decommissioning project.

After isolating the 200-foot-long diversion structure that has blocked the Hood River since it was built in 1923, workers started breaking apart and hauling away many tons of concrete, most of which will be buried in large pits near the site. With the project’s permitted in-water work period ending Sept. 30, crews will have to make fast work of removing the dam, reshaping the riverbed to a natural grade and taking out the two large cofferdams and fish ladder used to reroute the river around the project.

While workers from Weekly Bros. Inc. — the prime contractor PacifiCorp chose for the roughly $2.4 million project — are busy stirring up dust at the project’s upstream location, downstream at the powerhouse just outside Hood River things have settled and public access to the site has been reopened. Earlier this year a small crew and two large cranes carefully took down, piece by piece, the tall green tower and surge tank that took the humble honor of being the tallest structure in town for many decades. Inside the powerhouse much of the old equipment has been cleared out, with only the gear left to manage the transfer station that is still in operation.

“The project has gone very well,” said Todd Olson, PaciCorp project manager, who led a tour of the sites last week. “Everything has been very smooth, which is important for the contractors since they are on a pretty strict timeline.”

Olson brought a group of about 15 people on Thursday morning through the lower powerhouse, then up to the dam site for a tour of the project’s progress. With no significant complications to speak of, the tour was a fairly straightforward explanation of what has been done so far, what crews are currently doing and what is left to do in the near future.

Once the dam is removed and the riverbed is shaped to a natural grade, the river will be released, free to flow unrestricted for the first time in nearly 100 years.

Concrete extended about 18 feet below the bed of the river, so a huge hole had to be dug at the downstream side of the dam to get to the base of the structure. The hole will have to be filled in strategically so that over time material doesn’t wash away, leaving an unnatural section of river or rapids.

Olson explained that the goal is to create a section of river where, once vegetation around the project is restored, it looks and flows just like any other part of the river. If all goes as planned, local kayakers will not have a new set of class-4 rapids where the dam once was.

Up and downstream fish access has remained open throughout the project. Currently, fish can travel downstream in either of the two side channels used to direct the river around the dam. Upstream access has been limited to the dam’s old fish ladder, which was used from 1923 until about 1999, when the Oregon Department of Fish and Wildlife built an on-site facility used to regulate and count fish traveling upstream. The facility was reduced to rubble as part of the decommissioning project; where it once was will eventually be a restored riparian area.