By Brian Mittge, The Chronicle, The Chronicle, 1/13/2001
Although it does not intend to participate with Centralia on a regional wastewater treatment plant, Chehalis has been part of a regional treatment plant for a generation.
Since 1979, Chehalis has processed wastewater from Napavine and from Lewis County Sewer District 1, located along Jackson Highway near Newaukum Valley Golf Course.
This arrangement will continue as Chehalis develops a new treatment plant in the next seven years.
Chehalis' 52-year-old plant, located just west of the city near Exit 77 from Interstate 5, has plenty of capacity, but cannot be upgraded to meet water quality standards set by the state's Department of Ecology.
In addition, the current location routinely floods, and personnel often must commute to the plant via boat during winter months.
A new wastewater treatment plant is planned, but city officials haven't yet picked a site. If the prospective sites don't work out officials likely will grudgingly build a new facility at the old location.
This plan would require flood mitigation and the complexities of keeping the old plant operating while building a new facility on the same small piece of ground.
"If all else fails, we'll use the same site," said Jim Nichols, Chehalis public works director, adding that, ideally, "if you want to do it right, you don't try to bubble-gum-and-Scotch-tape it at the same location."
Chehalis has until 2008 to build a new wastewater plant to comply with DOE requirements for dissolved oxygen and biological oxygen demand in its effluent.
During periods of very low flow in the river, generally the warm summer months, the city will not be allowed to dump any treated water into the Centralia Reach of the Chehalis River.
This slow-moving stretch of water, roughly between where the Chehalis River meets the Newaukum and the mouth of the Skookumchuck, exhibits lake-like conditions during the summer, and has no capacity to handle extra BOD, according to DOE watershed specialist Kahle Jennings.
Under a consent decree with the DOE, Chehalis must avoid dumping into this stretch of water, instead piping its treated effluent miles downstream to be dumped below the Chehalis River's confluence with the Skookumchuck.
Chehalis has opted to keep its water out of the river entirely. The city intends to plant between 100 and 200 acres of hybrid poplar trees, a thirsty variety officials hope will gulp the 1.1 million gallons of grade A treated wastewater the city's new plant will produce during the average summer day.
As a backup, the city will still have to build a pipe to haul water down to the Mellen Street area in Centralia.
"It's like an insurance policy," Nichols said. "It's a lot cheaper and easier to do it now, instead of creating a whole separate situation down the road."
The $3 million pipe, which would carry treated wastewater during non-summer low-flow periods, such as this dry winter, is already included in the $30 million budget for the plant, Nichols added.
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