Here's What You Missed At The Tour
Glasgow’s most expensive public works project doesn’t get the respect it deserves. It cost nearly $6 million and took a decade to go from planning to performance. The system is unique in Montana, packed with energy-saving features and it harnesses biological processes to keep the Milk River water pure.
But it gets no respect. It slinks around under a pseudonym: WWTF. Waste water treatment facility. It’s a sewage plant, one of the fundamental services required of civilization. The full, double-barreled scientific description of this state of the art facility is provided by Rika Lashley, one of the engineers from Morrison-Maierle who designed it: a four-cell, covered, aerated lagoon system with post-nitrification.
A public invitation was extended to tour this fine new structure at Sullivan Park last Friday, to “see how we get rid of the poo.” Apparently this is not something people want to think about, not even with free beer as an added incentive. Of the 10 people at the event, four could be classified as members of the public and one of those was the operator of the Hinsdale sewage treatment plant. The other six were city officials or engineers with the project.
If it was the fear of bad smells and sights that kept people away, they would have been pleasantly surprised. The covered lagoons and the air management systems practically eliminate odors and there’s no visible waste. Any collection of cows or pigs or gym socks smells more potent than the WWTF.
If people had come, they would have toured the process step by step, from the screening of the “influent” (as the sewage is called when it enters the facility) to its transfer to two huge lagoons for aeration and settling, followed by ammonia removal in the post-nitrification reactor and a final blast of ultraviolet light to kill harmful E. coli bacteria before release into the river as effluent.
The process that transforms messy sewage into tame discharge is the natural action of living bacteria that come with the influent. The lagoon system consists of two earthen basins with thick synthetic liners, each subdivided into two cells. The lagoons are topped with 4 inches of rigid insulation that keeps water at the correct temperature, even during a Montana winter. This is the unusual feature of Glasgow’s system. Powerful floating mixers and submerged fine-bubble diffusers force oxygen through the water for the bacteria. If the “bugs” are kept happy, the process ticks along without any chemicals. They consume most of the solids, although the settling cell will need pumping every 10 years or so. Microbes even do the work of converting ammonia to nitrate.
“The environment selects for those bacteria that want to eat ammonia,” Lashley said. “We give bacteria the environment to do the job we want them to do.”
“This is biological treatment of wastewater,” said Jeremy Perlinski, an engineer with Morrison-Maierle. “We’re getting smarter and better about the environment.”
The average flow through the system is half a million gallons per day. Wastewater is pumped from the lift station next to the water plant on Glasgow’s south side to the WWTF where it discharges into the influent channel in the Screen Building. A basket-type ¼-inch fine screen removes rags and debris, which are washed, compacted and discharged to a garbage can for disposal at the landfill. That’s the only smell there is, and it’s in a small building.
Dave George, of Glasgow’s Water Department, said the WWTF is visited by a water operator once a day, and it takes about half an hour to read all the equipment.
Construction of the new facility was necessary for several reasons. The existing lagoon system was 35 to 40 years old and had become unreliable in its performance. Aeration equipment was at the end of its design life, with portions of it not working at all. In addition, regulations and stricter DEQ permit limits required treatment processes that the existing lagoon system was not capable of performing. Ammonia, which is toxic to aquatic life in high concentrations, was one of the new restricted substances that had to be removed from Glasgow’s effluent.