BAs much as $40 million in contract work to upgrade Spokanes waste-water treatment plant will be filtering through the economy here later this year, with much of the work to be awarded in the fall.


Between about $30 million and $33 million will be spent to build and install two new digesters to replace a digester that was destroyed in an explosion last May that killed one worker and injured several others.


Digesters process sewer sludge, and are critical to the waste-water treatment process, says Lars Hendron, principal engineer in the citys wastewater capital improvement program.


Its a nervous time, says Hendron. The two old digesters are the same design as the one that failed. They take more than two years to build. So were keeping our fingers crossed that we dont have another failure.


The new digesters will be more efficient than the current sewage tanks, says Jim Correll, Spokane-area manager of CH2M Hill Inc., the environmental-services company thats overseeing the upgrades at the waste-water treatment plant.


They will be state of the art, says Correll. They will require less energy to operate, and they will be efficient, and will require less maintenance.


The funds for the projects will come from the plants capital improvement budget. Because of the accident, the digester project was moved forward, and other projects were rescheduled for a later date, Correll says.


The digesters will be made out of steel instead of concrete, which will be safer, he says.


The city will decide the fate of its old tanks later. They could be converted into storage tanks or demolished. The damaged, but still standing tank that failed likely will be demolished, Correll says.


The new digesters will have a dramatically different appearance than the old tanks. They will resemble giant eggs instead of squat tanks. The new digesters will be about 130 feet tall, which is 90 feet taller than the tanks in place now.


The digesters will be held in place by a giant mechanical infrastructure that will be partially underground. Correll says the plant is trying to minimize the visual impact of the digesters by partly burying them.


Before work on the digesters can start, the city plans to build about a $7 million structure to house the plants steam boilers, which generate heat for the plant. The current boiler building is outdated and too small to meet the demands of the sewer plant, says Correll. The job of building the new one likely will go out to bid in the coming months, and the work could start shortly after the contracts are awarded.


The jobs are part of $100 million in planned capital improvements at the plant located at 4401 N. Aubrey L. White Parkway. Those capital improvements, some of which already have been done, are scheduled to run through 2007, Hendron says.


Correll expects there will be multiple contracts put out to bid for the 2005 projects, including big excavation, mechanical, and concrete jobs.


Weve had trouble getting local contractors to bid on our projects, says Hendron. We would like to keep it local. On most of the projects weve tried to keep the magnitude under $10 million so that it doesnt restrict who can bid.


Hoffman Construction Inc., of Spokane, recently was awarded a $10 million contract to upgrade the plants infrastructure and improve safety and efficiency systems. That work is expected to start shortly and be completed this year.


The treatment plant, which was built in the 1950s, was upgraded in the mid-70s, Hendron says. Portions of the latest renovations were completed in the late 90s, including an electrical upgrade and construction of a data center.