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Rangely’s Water and Sanitation Department prepares drinking water and treats wastewater released back to the White River. It is a complex system that requires a significant investment in time and money.
During the past five years, about $5 million have been invested in the intake, treatment plant, storage, delivery, pollution control systems and discharge site, Town Water Utilities Supervisor Alden Vanden Brink said.
Facing outdated infrastructure and limits on the capacity, Rangely has steadily improved almost every aspect of the system. First was the replacement of impeller pumps that sit in a well house fed by an intake on the White River above Douglas Creek.
When the river is high it can contain more sediment and when it is low it may have more organics, Vanden Brink said.
Depending on natural variations in the White River, taste and odor issues can occur.
“Total Organic Carbon (TOC) and sediment are the biggest treatment problems we have,” he said.
There have been a few times when White River was low enough to threaten the ability of the plant to operate at normal capacity. Rangely has been fortunate to not have a prolonged drought, since there is no storage for town water supply in Kenny Reservoir.
Water from the White River is pumped from the intake well house to settling ponds on the south side of Highway 64. Sediment suspended in the river water falls to the bottom of the ponds and is periodically cleaned out with heavy equipment.
During the busiest time of the year, such as July and August, water continually moves through the system. Settled water from the intake ponds is piped to the treatment plant or the golf course.
Domestic water has been supplied to Rangely during all renovation phases, making construction complicated. Maintaining a constant water supply was accomplished by duplicate systems, which allow units to be taken off-line for servicing or refurbishing.
Recently completed treatment tanks sit parallel to older tanks. When one aspect of the water system is completed, it is time to redo another part of the system.
“Like the ugly kitchen remodel, you never know what you will find until you get into it,” Vanden Brink said.
Renovations are designed to last 20 to 30 years, but there is continual maintenance performed by five city workers, he said, adding that newer equipment has led to fewer maintenance tasks, such as rebuilding intake pumps.
“But, we are far from being done replacing infrastructure and equipment,” Vanden Brink said.
The treatment plant will have a total capacity of 4.2 million gallons per day (MGD) after the current renovations are complete, he said.
Treatment plant tanks use chemicals called flocculants and mechanical mixers to help bind small particles into aggregates that can be filtered out. Particles can be organic such as left over pieces of river plants, algae and nutrients (TOC and nutrients) or might be inorganic, made up of small pieces of soil or salts (sediment).
Aggregated particles that don’t settle to the bottom of a collection basin are removed using a filtration tank with activated carbon. The carbon is an anthracite coal and can last 15 years when back-flushed one to two times per week. There will be three filtration tanks when the current construction phase is complete.
The last step of water treatment is a chemical process that involves chlorinating the water to kill any bacteria and adding fluoride for public health. Every stage of the process is electronically controlled, monitored and water is continually tested to ensure it is safe.
Federal and state drinking water requirements and administration needs, such as billing, are accomplished by another four workers. The vigilance of water utility workers protect the integrity of Rangely’s water system.
The treatment plant has a second set of six pumps that move treated water to four storage tanks located at high points around Rangely. The water tanks can store up to 72 hours of normal water use and are used to help maintain pressure in the distribution system.
Much of the water used by homes and businesses in Rangely becomes wastewater, and pollution must be removed before it is released back to the river. Pollutants such as human waste, food scraps, oils, soaps and chemicals are added to water as it is used in kitchens, sinks, showers, bathtubs and toilets.
Not all the pollutants are removed. Instead they are controlled, meaning they are brought to acceptable levels. The primary function of pollution control consists of breaking up and processing large particles into smaller particles.
“Pollution control is the business of bugs,” Vanden Brink said.
Bacteria and algae fed by oxygen are used to consume organics and break down materials so they can be removed or released in the form of gases like methane, nitrogen and carbon dioxide, he said.
In industry terms, the strength of sewage is measured in biological oxygen demand (BOD). BOD is the amount of oxygen the bacteria and algae need to break down organics into their chemical elements.
“Ninety-five percent of the BOD can be treated with the pollution control measures in place,” Vanden Brink said. Treatment ponds are lined to protect groundwater and consist of aeration and mixing equipment with the goal to “keep the bugs happy.”
Ponds can last up to 20 years before they need to be cleaned out,” he said. “The leftover solids can be disposed of in a landfill or, with precautions, can be used in land reclamation since the solids are high in nutrients.
A recently installed diffusion system made up of four pipes in the deepest part of the main channel discharge treated water back to the river making the cycle complete.
“Water is a precious commodity, an enormous amount of effort goes into keeping it flowing,” Vanden Brink said.