Underground Spill Controlled, Wwp Says Network Of Wells, Pumps And Pipes Will Start Bringing Oil To Surface

The blob that came from the steam plant is under control at last, according to Washington Water Power Co. officials.

Late Tuesday afternoon construction crews finished the last underground column of grout in a line that runs from the intersection of Lincoln and First eastward past the Rodeway Inn, then south about halfway to the Burlington Northern & Santa Fe Railroad overpass.

Trapped behind the barrier are an estimated 75,000 gallons of thick oil that once threatened to gum up redevelopment efforts in the area.

A network of wells, pumps and pipes will start bringing the oil to the surface by the end of the year, said Bob Mansfield, WWP’s neighborhood liaison for the project.

The oil leaked from tanks buried next to a WWP steam plant that heated many downtown buildings until it was shut down in 1986.

The leak was discovered in 1982, but the amount of oil that had escaped was underestimated. No attempts were made to clean it up until traces were found 400 feet away and four stories below ground.

That was 1994. WWP and state Department of Ecology officials agreed on a plan for removing the oil in late 1996.

Meanwhile, plans for rehabilitating The Davenport Hotel were put on hold, paralyzing a broader effort to create an arts district focused on the hotel and steam plant.

The hotel owners decided to proceed with renovations once the cleanup was announced, and executive director Jeffrey Ng said they are very satisfied with the progress made so far.

When the dust got bad, he said, WWP provided free car washes and two parking slots in the Rodeway basement to help solve the problem.

The contractors have done a good job of working with the neighborhood, Ng said.

Work on the $13 million project started in June. Mansfield said work has proceeded on time and within the budget.

Construction of the barrier was the most complex and disruptive step, Mansfield said.

Shafts were drilled down to the basalt that underlies downtown. Then high-pressure water jets carved out hollows 3 feet in diameter that were filled with grout.

The grout columns overlap, forming a continuous wall.

One stretch of the barrier is slightly lower than the rest. Any oil that breaches the wall should flow through at that point, where it can be captured by backup pumps, Mansfield said.

Wednesday, crews were packing up the batch plant and other equipment used in pouring the barrier. A backhoe in the middle of First was helping repair one of two breaks in city sewer lines caused by the water jets.

Mansfield said one line was unmarked on city maps, the other was marked inaccurately.

When those repairs are finished, he said the street will be repaved and traffic flow - interrupted since June - can return to normal.

Other crews will complete the wiring and conduct tests before the system becomes operational, Mansfield said.

Besides the barrier and pumps to capture oil and ground water, the system includes “bioventing” equipment that injects air into the ground to help nurture bacteria that digest oil.

Mansfield said surface runoff will be pumped into another set of tanks near the steam plant. By holding the water until a storm passes, then lifting it into the city’s storm-water system, the tanks will prevent overflow, he said.

All the systems will be managed by a controller located beneath the Rodeway Inn. Mansfield said AGI Technologies will monitor the equipment from Bellevue, making adjustments as necessary.

WWP will also have access to the controller, but does not have the expertise of AGI, Mansfield said.

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