For several years, the city of Lebanon has been working toward building a new water treatment plant because the current one is aging and nearing its capacity.
Overall, city staff are happy with how well the plant is working considering its age, said Ron Whitlatch, city engineering services manager.
“It’s just to the point now where you’re starting to get into that age where you run a risk if you don’t do something,” Whitlatch said.
If anything in the system breaks down, there are no alternatives to keep the plant functioning to meet consumer needs, he said. What’s more, the facility’s capacity is maxed out for Lebanon’s population.
The current plant pushes out about 3.6 million gallons of water day, and it might be able to produce as much as 4 mgd, but that’s the limit, Whitlatch said. The city wants to build a new plant that will have a rated capacity of 6 mgd.
That number will cover Lebanon’s current need and projected growth, said Rob Emmons, engineering services supervisor.
“(Water treatment plants) only last for so long, and we’re at that point where in order to grow and maintain a good capacity, it’s time to build a new plant,” Whitlatch said.
How the water treatment plant works
Lebanon’s water treatment plant was originally built in 1946 and modifications were made to it in the 1960s and 1980s.
“If there’s an earthquake, run, don’t duck,” Whitlatch said while touring the plant. “It has no structural integrity at all.”
The plant pulls water from the canal to the brick building through a metal screen wheel, which can be seen on Second Street.
“That screen is designed to keep the bigger stuff out of the filters,” Whitlatch said.
So the water passes through the screen, and the wheel turns in order to push wood and other debris away from the screen and back along the canal, he added.
Pumps stationed inside the brick building push the water into the accelator, a large holding tank that allows heavier solids to separate from the water and settle to the bottom.
It is one of the few remaining accelators in the nation because they are old technology, said Jeff Houchin, water treatment project manager. Albany’s water treatment system has two of them.
“(In the accelator) we mix the water with a coagulant, which attracts the dirt particles together,” Houchin said. “Then we take the cleaner water off the top.”
The finer particles that don’t collect and settle to the bottom will pass with the water to the next stage of the process, a mixed media filter, he said.
The mixed media filter is a pool about seven feet deep that uses nature’s own tools to remove the particles.
“It’s charcoal and different layers of agragate,” Emmons said.
Each layer is a bed of rocks that are small at the top and become increasingly larger toward the bottom. Emmons said this filtering system was added to the treatment plant in the 1960s.
“(The water) filters through there and takes out the fine particles,” Emmons said. “It’s old-school, but it still works.”
After filtration, the water is chlorinated and treated with fluoride before it is sent to the city’s distribution center, ready for sinks, toilets, showers and yard faucets.
“What’s not initially consumed by the consumers goes into the storage reservoirs,” Houchin noted.
Waste water treatment process
After residents use the water, the waste heads to the waste water treatment plant.
Unlike the water treatment plant, the waste water treatment plant is not in need of any major repairs or renovations at the time.
Lebanon’s waste water treatment plant, located on Tennessee Road, was built in the 1970s, but most of the equipment is replaced as it wears out, Houchin said.
However, much of the sewer system is more than 70 years old, Whitlatch added. The pipes were made from clay, so groundwater leaks into the system, and they are slowly being replaced as time and budget allow.
The waste water plant receives an average of 1.5 to 5.5 million gallons of sewage a day, depending on the season, Houchin said. On a heavy rain day, the plant processes as much as 20 million gallons.
Whether by storm drains or human disposal, all waste water ends up at the waste water plant.
“Everything that comes out of your shower, your sink, everything that gets flushed, (it all goes) into the wet well,” Houchin said.
As for those who question whether it’s okay to urinate in the shower, Whitlatch said “it all goes to the same place.”
From the well, a portion of sludge is set aside for a later purpose, while the rest is pumped into the headworks where an autorig rakes out debris.
“The headworks performs the duty of screening out large junk matter—basically any plastics, wood or sticks that happen to get flushed down the system or in the system from a manhole,” Houchin said.
Workers at the plant have seen items such as false teeth, cell phones, jewelry, money, mop heads, clothing, toys and drug bags filter out of the system, he added.
Paper and cloth that enter the system are also raked out, washed and sent to the landfill, Houchin said. That includes disposable wipes, which cause problems at the plant.
“They say they’re flushable, and they are, but they don’t break down like they’re supposed to or should,” he said.
“Those are bad news,” Whitlatch added. “They clog up our various pumps in the process; they clog and bind the pumps.”
After disposable wipes and other large debris are removed, the remaining raw sewage is aerated, creating a large sloshing effect.
During this process, grit and sand settle to the bottom while bacteria “bugs” feed on the sewage, Houchin said.
“A waste water plant is all biological-driven, it’s not chemically-driven,” Houchin said. “So this is all a natural process that you condition the right way, and the microbiological bugs take care of the process.”
They need oxygen to remain strong, so the sludge that was set aside earlier is introduced at this point, he said.
“We introduce that back into our process here so the healthy bugs will eat those younger bugs to get an oxygen source out of them,” Houchin explained.
Using reserved sludge in this way is one of the latest upgrades the plant has introduced into the system to help reduce solids, he said.
“It’s a new thought process and we’ve actually got it working quite well,” Houchin said.
This system reduces solids by about 50 to 60 percent, Whitlatch added.
“The waste product always has some material in it that you have to get rid of that you can’t return back into the system,” Houchin said. “So if we can reduce that naturally, it saves us in the long term from having to take this product out and haul it over a road.”
The next step is for the sewage to go to the clarifiers, where it has time to slow down and settle, he said.
“The solids will settle out because it’s heavier, and the clear water comes to the top,” Houchin said.
The clear water is filtered out, treated with chlorine, and then disinfected with sodium bisulphate which deactivates the chlorine before being sent back into the Santiam River from which it originated.
“So the effluent we send to the river is cleaner than the river itself,” Houchin said.
As for the solids that are removed from the water, it’s thickened up and used as fertilizer for farmers’ grass fields, Houchin said.