News and Opinion from Sisters, Oregon
News and Opinion from Sisters, Oregon
A few Sisters citizens are exploring alternative sewer systems. They believe alternatives could be cheaper and more efficient than the system voters are being asked to approve on May 19.
However, Dick Nored of HGE, Inc., the engineer for the system now being considered, believes the conventional municipal system his firm has designed is the least expensive in the long-term, the most efficient and lowest in maintenance alternative for Sisters.
The most common alternative systems are "septic tank effluent systems," where sewage goes from houses and businesses into individual septic tanks. Then only the effluent is pumped or flows by gravity into sewer main lines and is carried to a treatment plant for final "polishing."
Because the effluent is "pre-treated" in the tanks, some towns that have used these "STEP" (septic tank effluent pump) or "STEG" (septic tank effluent gravity) systems have been able to drastically reduce the size of their treatment facilities. This cuts the costs of projects considerably.
But Nored noted that those savings are not possible in Sisters because the Department of Environmental Quality requires that the Sisters system hold effluent during the winter and spray-irrigate with it during the summer.
According to Nored, that means the plant has to be virtually the same size no matter what kind of collection system is used.
"Basically we end up with the same financial cost," Nored said.
Nored said that alternatives "have been looked at in depth" in the HGE facility planning. According to Nored, STEP or STEG systems would actually be more expensive than the conventional system HGE proposes.
Nored calculates that a STEP collection system, which pumps effluent from each tank into the mains, would cost a total of $7,491,000 to build. A STEG system, which uses gravity instead of pumps, would cost $7,030,240 to construct. The proposed conventional system rings in at $6,463,000.
In addition, Nored maintains, STEP and STEG are higher maintenance, requiring septic tank pumping every five years, and tank replacement every 10-20 years depending on the corrosiveness of the effluent. STEP also requires pump maintenance and replacement.
Nored calculates the yearly operating and maintenance cost of a conventional system at $37,350, while STEG would cost $78,220 and STEP $99,520.
Nored noted that monthly charges of at least $35 would be required if the project receives grant money, no matter what kind of technology is used.
HGE has designed STEP and STEG systems for communities in Oregon. Nored said they were particularly good options when federal EPA grants offered 20 percent funding for the use of alternative systems. Those funds are no longer available, he said.
"If they were (available) that would make it (STEG) a stronger consideration here," Nored said.
Nored said the biggest practical drawback to STEP and STEG technology is the potential for odor problems in areas that have inversions. He noted that an HGE project in Mill City has had odor problems with tanks and venting systems, although he said those problems have been mostly overcome.
One alternative technology that Nored would like to see considered for some parts of the Sisters project is a vacuum system, which uses suction to pull sewage from a building to the main.
Vacuum systems allow smaller main size and shallower pipe depths, making it a cheaper alternative, especially for low density areas like Rolling Horse or Buck Run. The vacuum system would have higher maintenance costs, Nored said.
Nored said that HGE's fee for managing the sewer project - which would be put out to public bid - would not be much different if alternative technologies were used. In fact, based on a percentage of project cost, they could be higher with an alternative system.
"I'm trying to come up with the least expensive alternative because I think it's the only way we can build it," he said.
Jim Cornelius is editor in chief of The Nugget and author of “Warriors of the Wildlands: True Tales of the Frontier Partisans.” A history buff, he explores frontier history across three centuries and several continents on his podcast, The Frontier Partisans. For more information visit www.frontierpartisans.com.
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