By Jeremy Schwartz
Peninsula Daily News
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The piping was once the internal structure of the 5-million-gallon tank, said James Burke, the city's project manager for Port Angeles'
$41.7 million combined sewer overflow, or CSO, project, the $17 million first phase of which is currently under way.
The piping helped treat the industrial process waste that was once stored there when the mill operated, said Keith Parker, the on-site CSO project manager with Vanir Construction Management, Inc.
Crews from Ferndale-based IMCO General Construction have been working since September, with expected completion in late spring 2013, to renovate the tank for use as storage for untreated sewage and stormwater.
The sewage and water will be sent to the tank via miles of polyethylene pipe currently being installed across a portion of the Rayonier land, once the site of a pulp mill that ceased operation in 1998.
Burke said the city didn't need the internal structures of the tank, which was built in 1979, and the unneeded pipe debris will be disposed of by Rayonier.
The tank, with enough space to hold the liquid in 25 William Shore Memorial Pools, will keep the untreated material in storage until it can be treated by the city's wastewater treatment plant and sent into Port Angeles Harbor as part of the city's larger CSO project.
“It's just two completely different purposes,” Burke said.
Most recently, Burke said IMCO crews have nearly finished covering the interior of the tank with a special epoxy coating that will help the metal walls resist corrosion from the untreated stormwater and sewage it will store.
The goal of the CSO project is to increase sewage and stormwater capacity between downtown Port Angeles and the wastewater treatment plant to reduce the number of events, referred to as combined sewer overflows, that historically have sent untreated stormwater and sewage into Port Angeles Harbor during heavy storms.
The state Department of Ecology has given the city until 2016 to complete the CSO project or face fines of up to $10,000 for each additional combined sewer overflow that happens after the deadline.
Renovation on the 5-million-gallon tank also will add an external stair tower so the top of the tank can be accessed for maintenance, Parker said.
Crews will build a pump station just north of the tank that will move stormwater and sewage up the side of the tank, Parker added.
The tank will be fed from three pipes currently being installed on the Rayonier site that will eventually run underground through the site, roughly parallel to the Olympic Discovery Trail and stretch to downtown Port Angeles, Burke explained.
To construct each separate diameter of pipe, 24-inch, 30-inch and 36-inch, crews will fuse together smaller sections using a heating method that binds the section ends together rather then being screwed into one another, Parker explained.
“So there's really no joint that's going to leak on this pipe,” Parker added.
The pipe will run underground between downtown Port Angeles and the tank, except when crossing Ennis Creek, where crews are working on a new, 105-foot-long concrete bridge that will also carry the Olympic Discovery Trail over the creek, Parker said.
The new bridge will also be built high enough to allow later creek restoration, Parker said.
“That's all well above the flood level of the creek,” he said.
The concrete bridge abutments, which have been poured on each side of the creek, will hold concrete girders on which the trail will run, Parker explained.
Reporter Jeremy Schwartz can be reached at 360-452-2345, ext. 5074, or at email@example.com.