Cottage Grove’s Row River Water Treatment Plant has kicked its expansion project into high gear, entering the final leg to increase the plant’s water treatment capacity.
“We’ve put several months of work into getting up to this point getting a lot of the physical labor done and now we’re going to start doing the final tie-ins to get it all buttoned up,” said the plant’s Water Production Superintendent Ryan Kimball.
Plans for the project were solidified in a vote by the Cottage Grove City Council Sept. 23, 2019, to expand the plant’s water treatment capacity from four million gallons per day to six million.
Coming in at a final cost of just over $1.1 million, the project is intended as a proactive measure to address a number of city issues for years to come.
“I think the biggest importance for us is that it gives us room to expand,” said Kimball. “As the city grows, we’ll be able to meet demand and it’ll give us redundancy in the racks.”
The plant currently operates with two membrane racks, each able to push 2 million gallons of water through per day.
If one of the two racks go down, there could be a significant strain on the plant.
Kimball said he has observed the city using more than three million gallons per day and, at last year’s Sept. 23 city council meeting, City Engineer Ron Bradsby reported the number at three-and-a-half million gallons.
“This gives us a little wiggle room and it’ll be easier to bring racks down and do maintenance on them individually, so it gives us a safety factor as well,” said Kimball.
In addition, sudden increased usage of city water due to firefighting, such as the case of last summer’s spate of house fires, can be a heavy draw on the amount of water available.
“It absolutely increases our ability to fight fire,” said Cottage Grove Civil Engineer Ryan Sisson.
Maintaining the city’s access to water is another reason behind the project.
“There’s also the aspect of our six-million-gallon water right and we don’t want to lose that,” said Sisson.
Demonstrating that the city can produce the amount it holds the rights to is key to keeping those rights, which Sisson said would be difficult to recapture once lost.
“And as the city grows, there maybe come a day when we need that,” Sisson said.
Water Quality in The Grove
The expansion not only covers city concerns for some time on the horizon, but also triples down on Pall Corporation’s hollow fiber membrane system, a technology Kimball readily gushes about.
“What’s impressive for me is just how efficient it runs,” he said. “It’s really clean technology and it’s been really fun to operate.”
The microfiltration technology consists of series of tubes, each of which is packed with tiny filaments with .1-micron pores. The process resembles pushing water through thousands of miniscule straws.
“That’s kind of the leading edge when it comes to water filtration principles,” said Lucas Albrecht, lead systems field engineer with Pall. “As far as meeting any and all requirements and regulations from a health perspective, this is the best kind of filter you can have.”
While the tech offers this quality advantage, Kimball attributes the plant’s level of water quality to the staff’s dedication and thoroughness as well.
“We baby this plant,” he said. “We really put a lot of energy into making sure we put out the best product that we can.”
Comparatively, Kimball feels the technology and the plant’s production would seem to be on par or better than similar systems in the state.
“We’ve been sort of the poster child for membrane facilities,” he said. “We have a lot of tours and a lot of plants that come to us to see how we’re running because of how well we’re able to run this and the water we’re able to produce.”
In the world of water quality contests, too, Cottage Grove has its place.
“They have annual water quality contests in Oregon where all the plants submit their water and we’ve come in anywhere from 2nd to 8th,” said Kimball. “And we’re working against cities that are off of fresh springs.”
Kimball cites the low turbidity of the plant’s water, measured by NTUs (Nephelometric Turbidity Units), as a major factor in its quality.
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles and measurement of it is key to determining water quality.
“High turbidity can cause problems because it can interact with chlorine’s ability to disinfect,” said Kimball, adding he’s been proud of the plant’s numbers.
“The treatment is so effective that the water going out is just incredibly pure and clean,” he said. “The only thing we would like to do different is, in the summertime there’s a little bit of taste to the water that comes from organics in the water that die off.”
Minerals like iron and manganese naturally accumulate in the city’s water system and, though still considered safe to drink, can cause a yellow tint to appear in residents’ tap water.
The mineral deposits can be scoured through a flushing process, however the city had until last year not been meeting the once-a-year minimum recommendation of this process.
Several complaints from Cottage Grove residents surfaced last September about a hazy discoloration in people’s tap water.
City officials maintained that the water had passed quality tests and attributed the discoloration to a spike in house fires that had recently swept through the city.
The discoloration may show up in residents’ tap water when large quantities of water are used, such as in fighting fires and summertime plant watering, city officials said. This heavy usage can stir up the mineral deposits in the lines and get into household plumbing systems.
The city has since made flushing of city quadrants part of a weekly routine, a move Kimball applauded.
“Everything’s getting hit at least once a month, if not more,” he said.
Pathogens, too, are unlikely to find their way through the system.
“Those membranes can handle quite a bit,” said Kimball.
Though Dorena Lake will often play host to blue-green algae blooms, Kimball said the resulting cyanotoxins have never made it as far down as the plant’s intake.
In any case, the .1-micron pores in the system’s filaments prevent the most worrisome of organisms from breaking through.
The size of the giardia parasite, for example, is typically between 8 to 14 microns and a pathogen such as Naegleria fowleri, the brain-eating amoeba which recently killed youths in Florida and Texas, would also easily be caught by the system.
Though the city’s first two racks are more than a decade old, Kimball assured that the plant’s “aggressive” maintenance routines will keep the technology running for some time without need for replacement.
“They’re still functioning as if almost new. We’ve had very, very few issues,” he said. “We’re not going to be having any issues with them for a long time to come.”
The expansion project is slated to be completed in mid-December.
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