A La Plata County subdivision will soon have something new to brag about: a state-of-the-art wastewater system designed for high-altitude locations.
Edgemont Ranch Metropolitan District, about 650 homes northeast of Durango, is the first district in the United States to build the system developed in Austria. It’s a $7.5 million upgrade, but district staff members expect to reap environmental and financial benefits from the system.
“We’re going to be the showcase for America,” said Robert Ludwig, a wastewater operator with the district. By December, it should be fully operational, he said.
Wastewater facilities take sewage water, called influent, push it through multiple cleaning stages, and release the disinfected water, called effluent, into water bodies.
Edgemont Ranch releases its treated water into the Florida River. The high mountain stream typically has low water flow past the facility. By that point in the river, Durango has already diverted much of the water for its purposes.
With less water to dilute the treated water, Edgemont Ranch must release high-quality effluent to minimize impacts on the river.
“Algae was growing,” Ludwig said. “Even meeting the effluent limits, we could see that we were impacting the watershed. So we knew we had to do better.”
Then, in the cold winter months, the bacteria in the wastewater treatment lagoons were less active. The bacteria drive the biological processes that break down waste material.
Once the temperature falls below about 39 degrees, the biological processing shuts down, Ludwig said. The lagoons were not removing nitrogen and phosphorus in the winter.
“Any biological reaction is slower in low temperatures, whether it is a ‘bad’ one like spoiling food or a ‘good’ one like wastewater treatment,” said Peter Aichinger with ARAconsult, who assisted the metropolitan district.
High-altitude environments come with both low temperatures and low atmospheric pressure. Low pressure makes it harder to dissolve oxygen in water for the bacteria.
“They need to breathe like we do, and it is harder for them in high altitudes like it is for us,” Aichinger said.
In 2006, Edgemont Ranch realized the facility would not meet the subdivision’s long-term needs: an affordable system that minimized environmental impact and worked at high altitudes.
“We were a little gun-shy because Durango’s had such a hard time starting up their new process,” Ludwig said. South Durango and Mancos also had difficulty starting up processes. “They’re all technologies that have been adapted from lower altitudes. We wanted something that was a mountain (wastewater) plant.”
Staff members spent 10 years planning and finalizing permitting for a new facility. The district bypassed the option for a membrane biological reactor. It decided against the sequenced batch reactor used in Durango and many municipalities.
“They take a lot of energy, and they produce OK results,” Ludwig said.
In 2019, staff members decided to fly to Austria and Germany to visit towns using the BIOCOS wastewater processing system.
The BIOCOS system, or biological combined system, was initially developed for huts and cottages high in the Alps, Aichinger said. About 200 BIOCOS plants are in use in Europe and China.
The system was designed to be efficient. Typical treatment plants include complex electrical equipment and control methods, and require highly skilled personnel.
“If any of the equipment fails, the whole treatment might fail, too,” Aichinger said.
BIOCOS uses one blower station, performing treatment tasks like aeration and pumping using an airlift. It extends the biological reaction zone to give bacteria more opportunities to break down material, getting more work done in smaller water volumes.
For the metropolitan district, the system will process up to 175,000 gallons of wastewater each day. The district processes about 75,000 with its current system.
Construction will take place this summer and fall before ending by December, Ludwig said.
“When a wastewater plant is operating correctly, it kind of smells like detergent,” he said. “Because (these plants) process the wastewater so efficiently ... they don’t stink.”
With increased efficiency, Ludwig expected the facility’s carbon footprint to decrease and electricity costs to stay steady. The district plans to treat water using a UV disinfection system instead of chlorine to help keep the river clean, he said.
In the future, the facility can also be used for power production, Ludwig said. Biogas, produced when anaerobic bacteria break down waste material, can be used as fuel or to produce electricity.
“I’m excited to be able to protect the environment,” Ludwig said. “I’m really excited about how healthy it’s going to be.”