E. Coli levels at wastewater treatment plant under watch

Benny Westcott

The Sweet Home wastewater treatment plant experienced unusually high flow levels, followed by die-offs of biological life in its aeration basin, on a pair of Tuesdays two weeks apart, Aug. 9 and 23.

And Public Works Director Greg Springman hoped that, come Sept. 6, it didn’t happen again.

(Due to The New Era’s production schedule, those results weren’t available at press time.)

“We’re asking businesses to be cognizant of what they’re discharging and how they’re discharging,” he advised in a Sept. 1 interview. “If they have concerns with how they’re putting things into the sewer system, they should contact myself or (Sweet Home Utilities Manager) Steven Haney. We’ll be more than happy to come out and meet with them.

“If this keeps going, (the Oregon Department of Environmental Quality) is going to force us to start knocking on some industries’ doors. They’re going to want us to identify it.”

Originally built in 1947, the treatment plant last saw a major upgrade in 1974. In 2001, the City of Sweet Home reached an agreement with the Oregon DEQ to address ongoing wastewater system overflows and discharge violations primarily caused by inflow and infiltration in the collection system, which is water that enters the sewer system through deteriorating pipes and cross-connections with storm drainage.

On Aug. 9 of this year, the facility experienced double its usual flow of 700 gallons of wastewater per minute (GPM). For the next three to four hours, the influent level increased to 1,400. Within a day, the plant had lost nearly all the biological life in its aeration basin due to the unknown discharge.

Sampling was conducted when the plant became odorous. Test results at 12:30 p.m. Wednesday, Aug. 17, indicated E. coli levels exceeding the permitted level of 406 MPN, or most probable number

The city notified the Oregon DEQ, the Oregon Health Advisory and other agencies, then issued a press release to the public later that afternoon pinpointing the affected waterway downstream from the Pleasant Valley boat ramp. Staff recommended avoiding swimming or wading in the area, and signs were posted regarding the water quality advisory.

The following morning, city staff reviewed the Aug. 17 samples and determined that the system was back within DEQ compliance, with E. coli levels at 133.4 MPN. Then, a week later, test results again revealed high E. coli bacteria levels, but they’ve since returned to an acceptable range.

“From the original die-off, at two weeks we were actually turning the corner and starting to look better,” Sweet Home Utilities Manager Steven Haney recalled. “And then we died again. I’m hoping that we’ll be turning the corner early next week and things will really start looking better. ”

According to Springman, public works employees began adding ferric chloride to the wastewater on Aug. 26, which helped with odors and settling.

“It gets right into the sludge, grabs onto it, and gives it a little more weight because it’s iron,” he explained. “It helps it settle and fall out to the bottom. We’re tricking (the wastewater) into being treated. We’re getting it to settle out and then chlorinating the heck out of it, so we’re not violating.”

Staff have also been adding freeze-dried bacteria to the aeration basin. They’re also purchasing a pH probe for the plant’s influent wet well, which will track pH level adjustments. Wastewater samples are taken regularly, with their biological life levels examined under a microscope.

“If we see our flow come in and recognize that there is a pH change, we’re going to take that sample to our lab and run it for the full spectrum of constituents,” Springman said. “And that will give us a roadmap of what kind of constituents it is, content-wise. It won’t tell us it’s ‘whatever’ product. It will just say that it has ‘this’ in it. We want to be able to see it come into the plant, grab a sample of it and categorize the constituents. We can easily do that, and we’re planning to do that.”

That, of course, runs into money. The five pounds of engineered bacteria added daily to the wastewater costs $2,500 per month. The ferric chloride runs about $8,000, while the pH probe requires around $13,000. The Public Works Department has ordered a new portable auto-sampler which carries a price tag of about $8,000.

“We’re spending money trying to identify and stop,” Springman said.

“Although those costs are significant,” Haney added, “the potential DEQ fines could be more significant.”

Even tracking the plant’s flow levels can be somewhat challenging; Haney describes the equipment as “1974 telemetry. It’s me estimating numbers on a graph that are blurry. It’s a ballpark.”

Staff efforts to curb the biological life die-offs come amidst some public frustration.

“We’ve had a lot of customers complain,” Springman said. “We’ve had a lot of concerns over the odors. We’re getting beat up on Facebook and everything.

“We’re doing everything we can possibly do to keep this plant alive. I really need the help of the industry and the people of the community to be cognizant of what they put down the drain and get this thing back to life. It takes literally four to six weeks for us to build the proper life to eat the amount of poundage that we get in here. We just want to make sure that people understand that spent solutions should be contained and hauled offsite.”

He explained that spent solutions could be an array of any type of industrial products used in a process and then discarded.

“A good example of that is if you have a dishwasher in your house that you put dish soap in,” he said. “When it’s used, that solution has been spent. If you have a tank at your property or business and you do a cleaning of it, or if you need to change the solution, the old solution should be contained and hauled off-site or treated in some way, not discharged to the sewer as a disposal method.”

Springman doesn’t know exactly what caused the increased flows, though he has some ideas.

“The volumes that we got didn’t come from a truck,” he said. “This wasn’t a pumper truck company or a hazardous-waste company or something worse that just went and dumped it in the sewer line. This is a sustained flow for a period of time. It could be periodic cleaning of a business, like boilers or steam systems – any type of industry-type system that uses water in conjunction with chemicals in its processes.

“We’re just wanting to educate right now,” he noted. “We have a sewer ordinance that covers industrial discharges. If we have to initiate that, we will. But I think the reality is that we need to ask businesses to be cognizant of what they discharge and how they discharge.”

He said that sewage regulations are both local and federal.

“We have our local ordinance,” he said, “but it’s also based on federal regulations that have been adopted. We’re asking everybody to comply with those.”

As of Sept. 1, the aeration basin still had some odor. However, it wasn’t as bad as it was previously.

“It should smell like you just took a shovel and turned over wet dirt,” Springman explained. “It should have that earthy smell. It’s getting there, but it’s not there yet. But it’s a heck of a lot better today than what it has been.”

Still, if unusually high flow events and the resultant biological life die-offs continue, Springman said, “We’re going to be expected to start meeting up with some of our industry partners to have discussions and learn a little bit more about their businesses and how we can partner better.”

He noted the importance of the relationship between the city and industry.

“We have to coexist,” he said. “We have to have business, and we have to have our treatment plant. They need our treatment plant, and our community needs our treatment plant.”