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Consultants reveal latest sewer details
CARNATION _ Discussions on whether homes in Carnation
should abandon septic systems for city-wide sewers continued as officials from
the county, city and the sewer consulting firm disclosed more information
on the controversial topic.
American Engineering, the company hired to develop the sewer
plan, originally planned to present their sewer study to the city council at
the end of this month. However, the company is still waiting to hear
comments from government agencies and estimates that the document will be
available by May.
In anticipation of receiving the plan on time, the council has
scheduled a public hearing for May 16, with possible adoption of the plan on
May 30. Both meetings will tentatively be held at 7 p.m. at city hall.
If the council agrees that sewers are necessary for the city, a
workable system could be in place within the next three to five years, said City
Manager Woody Edvalson.
The sewage treatment plant will be located on a 10-acre lot along
West Entwistle Street that is zoned light industrial. The plant will only
utilize half of the property, which will accommodate large concrete basins to
hold the sewage, pumps, filters and a laboratory needed to run the facility.
"Will there be a stench? Absolutely not," said Einar Gundersen of
American Engineering about the concern over smells from the sewage
treatment facility. "There could be odors at times, but offensive? Probably not."
The company is proposing three sewer system methods to the city:
a conventional gravity sewer system, a vacuum sewer system and a
grinder pump system. Most cities have used the gravity system in the past, but
with increased technology, the vacuum and grinder methods have gained in
The gravity system uses angled pipes to transport the sewage from
the homes to the treatment center. This method has the highest
construction costs because the sewer pipes need to be installed about eight to 10 feet
in the ground.
"It creates a lot of commotion with existing streets. And manholes, if
not built right, rain water can go into the [sewer] system," Gundersen said.
However, it is one of the more reliable systems and it generally
costs less to maintain and lasts longer than its mechanical counterparts.
The city will also consider the vacuum sewer system that uses
small pipes that are buried only 30 to 36 inches in the ground _ which makes
it cheaper to install than the conventional system.
The waste is collected into a holding tank on the homeowner's
property that triggers a release valve whenever it gets full. The sewage is then
sucked to the treatment center. If the power goes out, this system would still
be operable because the electronic mechanism is based at the
treatment plant where there is a huge generator for times of emergency.
The grinder pump system, however, would shut down during
power outages because each home would be equipped with its own grinder.
And since it is a piece of machinery, Gundersen said homeowners
should expect some failures.
"It's a mechanical device that will break down at some time," he
said. "Like a water heater, you never really expect something to happen,
but something will happen."
He added that the 6-foot by 30-inch grinder has the capacity to hold
a couple days' worth of sewage in case the power does go out.
Whichever system the Carnation City Council decides on,
Gundersen said all three options are feasible for the city.
"Carnation is flat and tilts to the river which makes any of these
systems workable," he said.
Once the sewage is treated at the plant, the water will then be
discharged into the river or into a holding tank as non-potable water. So
far, several area businesses have shown an interest in purchasing the
reusable water _ which is not adequate for human consumption _ to irrigate
huge tracts of land.
"There will be times of the year where we will use 100 percent for
reuse and times where we'll discharge 100 percent," Gundersen
explained. "In the winter, there is no demand
for the water and no place for storage."
The city's sewer system is expected to be constructed in
three phases, with the downtown core transforming to the new system first
and newer developments joining in about 20 years. At full capacity, the
sewage plant will treat roughly 550,000 gallons of sewage a day.
But some residents questioned why they would need to wait two
decades to have sewers installed into their newly built homes.
Gundersen said that city officials could update
the scheduled phases, but it was assumed that homeowners would probably
not want to fund the new utility.
"The new area has a fairly new septic system that has a good life
and we didn't think you'd want to pay again," he said. "Is there an
urgent need in those areas right now? We don't believe so."
But the greater part of the population in Carnation will be expected
to pay for the sewer project; however, exact figures were not available
yet. Jim Morgan, of the Cosmopolitan Engineering Group, the firm hired
to conduct the financial analysis, described the future customer's
sewer bill as a combination of several factors including the amount of debt
the city must repay for the facility, user fees and the operation and
Grants and low-interest bonds would also be available to help the
city finance the sewer system at a fairly reasonable price, Morgan said.
More details about the financial aspects will be available when the city council
discusses the plan next month.
In the meantime, Mayor Bob Patterson will host an open house
from 10 a.m. to noon on Saturday, April 29, to discuss the sewer proposal and