Hugh Carey / hcarey@summitdaily.com
While most of us in the western world may take it for granted, modern sewage and wastewater treatment systems are critical to maintaining good water quality in modern municipalities. The Snake River Wastewater Treatment Plant in Keystone has been treating and reclaiming water for eastern Summit County residents for several decades now, and is looking to do some upgrades to keep up with the area’s growing water usage.
Summit County’s commissioners were taken on a tour of the plant Tuesday morning. Built in 1974, at its peak during ski season the Snake River plant processes and treats about 1.1 million gallons of wastewater a day with a yearly average of about 750,000 gallons a day and a theoretical maximum of 2.6 million gallons a day. The plant’s wastewater intake peaks every year on New Year’s Eve, when revelry means drinking which translates to a whole lot of toilet flushes.
The wastewater comes from sewers and drains, as well as from the many homes in the Snake River Valley in and around Keystone Resort. At the moment, the plant is servicing 6,900 “taps,” or home water connections in the area, with a capacity of up to 8,900 taps.
Given the massive amount of dirty water that needs to be treated daily, the process can be prone to breakdown, clogging and even hazardous events such as fires or explosions from built-up methane and other volatile compounds created in the treatment process.
Luckily, the plant more or less runs itself without incident. Plant director Chuck Clause said that at over 90,000 square feet, the treatment plant is by far the largest public building in the county; yet only eight human workers, including Clause, tend to the plant full-time.
The treatment process hums through an extensive industrial machine apparatus that sprawls around the complex, with nothing much but a computer keeping the entire operation up and running.
High-powered ventilation systems keeps most of the plant odor-free and with clean air, but despite its best efforts the smelliest portion of the plant – the headwaters screen, where the wastewater first arrives at the plant — is hard to mask.
The headwater screen filters out large solid items from the water, and is a critical component in the treatment process. Last year, the county approved $1.5 million to replace the headworks screens, which wear out after years of dredging, and they are slated to be replaced this year.
After the initial filtering, the wastewater goes through a secondary biochemical oxidation process. Biological bacterial agents — which Clause calls “bugs” — are dropped as a slurry into water being treated, and the bugs go to work breaking down all organic compounds in the waste, creating carbon dioxide in the process. Oxygen is fed into the slurry with a bubbler, with the oxygen encouraging bacterial growth and activity.
The bug-treated water then goes into a massive chamber called a clarifier, which separates all solid mass from liquid. That solid mass – known as activated sewage, is then rerouted for reuse, or put into a high-powered centrifuge to get rid of any remaining moisture, dried into a dirt-like product and put into dump trucks for disposal at the Summit County Resource Allocation Park’s compost pits.
The liquid portion of the water goes through a few more phases of chemical treatment and filtration before it is safe for reclamation. That includes denitrification, which causes ammonia from urine to be converted into nitrogen gas and removed, and a powerful dose of ultraviolet light, which kills disease-carrying microorganisms.
In the tertiary treatment stage, the water is also subject to phosphorous removal and then run through a sand filter, which gets rid of heavy metals and sendiment and essentially “polishes” the water before it is ready to be dumped back into Lake Dillon. The tertiary process is a mini-version of what drinking water treatment plants do, but without additional chemical processes such as adding chlorine.
Even though the plant is running smoothly at the moment, Clause and county public works director Tom Gosiorowski advised the commissioners that there are certain upgrades that need to be made at the plant. Specifically, Clause said the plant has “maxed out” on the denitrification process and it needs to be expanded. While the situation does not pose an immediate danger, the plant can’t do as effiicient a job removing ammonia from the water without increasing the processing capacity.
“We still have plenty of capacity to treat sewage, it’s not like we’re going to have to discharge raw sewage into the lake or anything,” Gosiorowski said. “But the ability to remove nitrogen out, we’re pushing the limit on that.”
The problem with the upgrade, as with most things involving public infrastructure, is the cost. Gosiorowski estimated that expanding the plant’s denitrification process will cost between $5 and $10 million.
At an upcoming work session, Gosiorowski will appeal to the commissioners formally with a cost estimate for the project and other potential improvements to the plant and the Snake River Valley wastewater system.