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Operators at the city of Sheridan Wastewater Treatment Plant run a settleometer test Wednesday, Nov. 4, 2020. The settleability test is an analysis of the settling characteristics of the activated sludge mixed liquid suspended solids. It is often referred to as “running a settleometer.” The test is normally done at the treatment plant rather than a certified laboratory. The idea of the test is to provide a place where the MLSS can quietly separate from the liquid water. The MLSS solids consist mostly of bacteria with some organic and inorganic debris mixed in. The debris can be finely shredded toilet paper, paper towel fibers, vegetable fibers, plastic material, seeds, insect parts — you name it.

SHERIDAN — A question has been dogging Sheridan County since a local woman was the first Wyoming resident to be diagnosed with COVID-19 this spring: What does the future hold?

The answer to that question may be found in the 2.5 million gallons of wastewater processed each day at the Sheridan Wastewater Treatment Plant, and it isn’t promising.

According to predictions made based on local wastewater testing, the number of locals diagnosed and hospitalized with COVID-19 will likely climb throughout November. The estimated infection rate in the county, determined by sifting through composite samples of local wastewater for COVID-19 biological material, has increased nearly six-fold since the first sample was taken in the county  July 24 and the estimated infection rate was 1%. In the most recently recorded sample Oct. 28, the estimated infection rate was 5.8%.

“Certainly, the wastewater samples in Sheridan and in most cities in the state are trending up,” said Franz Fuchs, policy analyst with the Wyoming Department of Health, who noted that there’s a lot of uncertainty in the estimated infection rate and  the trends were more valuable than the estimated numbers. “That means things are going to get worse before they get better.”

“We definitely noticed a difference in the data we were collecting at the end of August and beginning of September,” said Doug Rideout, city of Sheridan Wastewater Treatment Plant superintendent. “We could see the trends going up a few weeks before the reported case counts started going up. The case counts being reported by the Department of Health have been very similar to what we’ve been seeing in our data. If that trend continues, we’re definitely not out of the woods yet.”

Sheridan County started testing wastewater in late July, according to Rideout. The county was one of the first to jump on a Department of Health plan to test wastewater for COVID ribonucleic acid.

“We’ve always been innovative, and we were one of the first to contact them,” Rideout said. “We have a great wastewater treatment plant, and we were anxious to get on board and see how we could help.”

Statewide wastewater testing was instituted by WDH this summer in an effort to generate a “representative random sample” of COVID-19 throughout the state, according to Fuchs.

“What’s interesting about the wastewater is that it is hard otherwise to get a representative random sample of COVID in the community,” Fuchs said. “You can’t just walk up to random people on the street and shove a swab up their nose. But the nice thing about wastewater is it’s right there and readily available because everybody poops.”

Fuchs went on to explain that wastewater is useful from a data perspective because virus RNA will appear regardless whether the carrier is symptomatic.

“The problem with relying on case counts like the ones that the department releases everyday is that it is subject to people getting symptoms and deciding to get tested,” Fuchs said. “So that means we’re not counting people who are predominantly younger and may be asymptomatic. So the numbers we get from wastewater testing may be closer to the real number.”

The biological material of the virus is often found in wastewater before people are symptomatic, Rideout said. Thus, wastewater testing results provide something of an “early warning” for local health care providers and a prediction of what they might have to face in coming weeks.

The virus has been known to shed in feces, Fuchs said, and the testing process considers the virus’ half-life and degradation in the sewer — when compared to total gallons of wastewater, lab technicians can estimate the actual infection rate in the community.

Samples are taken every 30 minutes over a 24-hour period, with 100 milliliters of sample collected by the end of the day, Rideout said.  The samples are stored in a cooler at 20 degrees Celsius before being shipped out to the WDH, Rideout said.

The local wastewater treatment plant originally sent one sample to the state each week, but has since started sending multiple weekly samples to provide more data to the state.

“For at least the last month, we have been doing two samples a week, which just provides the state with more data,” Rideout said.

As of right now, Sheridan is one of 20 Wyoming sites — including towns, cities and Yellowstone National Park — reporting wastewater testing results to WDH. Of all the sites, only Cody (8.2% estimated infection rate), Gillette (7.9% estimated infection rate), Riverton (7.6% infection rate), Cheyenne (6% estimated infection rate) and Green River (5.7% estimated infection rate) have a higher infection rate than Sheridan.

The wastewater results mirror what is happening statewide with case counts, according to Fuchs. As of Nov. 5, WDH reported 189 active lab-confirmed COVID cases in Sheridan County. Only Albany (804 active cases), Campbell (747 active cases), Laramie (642 active cases), Natrona (612 active cases), Fremont (359 active cases) and Park counties (234 active cases) had more active lab-confirmed cases.

The high number of cases in the county — which Sheridan Memorial Hospital’s Chief Medical Officer Dr. John Addlesperger attributed to group gatherings throughout the county — remains concerning, according to hospital CEO Mike McCafferty. McCafferty said contingency plans could potentially include limiting nonessential surgeries and procedures at the hospital.

McCafferty said he continues to reevaluate the need to execute contingency plans to ensure both those with COVID and without can be served.

“We have to evaluate things every day,” McCafferty said. “We know that by mid-November, COVID numbers are going to increase. We just have to decide how to manage that number of patients with the number of staff we have available and how to allocate resources to make sure we’re caring for patients.”

Thursday morning, there were 12 hospitalized COVID-19 patients at SMH, according to McCafferty, but none of them were on ventilators. Just a quarter of the patients are age 60 and older —  the age group most susceptible to COVID, McCafferty said.

Both McCafferty and Addlesperger emphasized the importance of continuing to adhere to social distancing, masking and hand sanitization measures in an effort to flatten the disease curve and prevent the hospital from being oversaturated with COVID-19 patients.

“If people increased their mask use to even 95%, it would cut the state’s COVID cases by 2/3,” Addlesperger said. “It is a proven effective way to reduce the spread. Doing little things like that is our major defense against the spread of this virus.”  


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