Green and sustainable features permeate buildings and processes at Calgary’s advanced Pine Creek Wastewater Treatment Plant.
From green roofs to new odor control technology, one of Canada’s most technologically advanced clean-water plants is in Calgary, Alberta.
The Pine Creek Wastewater Treatment Plant opened in 2009 after five years of construction to serve a growing population. Built with a focus on sustainability, the $390 million complex has a LEED Gold certified administration and operations building and the latest innovations in wastewater treatment, according to George Kewley, operations supervisor. The plant (26.4 mgd design, 21 mgd average) has a 30-person staff, including 20 operators on four rotating shifts.
Treatment begins with 6 mm perforated screens followed by highly efficient cyclone grit removal. The primary clarifiers are rectangular for a smaller footprint. The two 82,000-cubic-foot biological nutrient removal bioreactors use the Westbank configuration for enhanced phosphorus and nitrogen removal.
The four 150-foot-diameter circular secondary clarifiers have a rapid sludge removal system for better mixing. From the clarifiers, the flow goes through disk filtration and UV disinfection before discharge to the Bow River, a rainbow and brown trout fishery that attracts anglers from all over the world.
“We put a lot of thought into odor control,” Kewley says. “Nobody wants a wastewater treatment plant in their backyard, and houses are getting closer and closer to the plant.”
All wastewater channels, grit tanks and blend tanks and the rectangular clarifiers are covered. Foul air is forced through one of three biofilters that consist of rocks covered with activated carbon. A microbiological film grows on the rocks and feeds on the foul air, especially the mercaptans and hydrogen sulfide.
The filters use biological media designed to last 15 to 20 years, whereas older filters with activated carbon and potassium permanganate need media changeout every one to three years.
Many green features increase sustainability and help the plant fit into the environment. “The buildings have 18,000 square feet of green roofs with drought-resistant native prairie grasses,” says Kewley. “That keeps them cooler in summer and warmer in winter.
“We have very little asphalt and lots of drought-resistant native prairie landscaping. We even have wildlife corridors that we’ll maintain as we expand the plant.” All storm drains inside the fence line flow to the headworks. Dry ponds collect runoff from the rest of the site so that it evaporates instead of reaching the river.
Half the plant’s electricity comes from a wind farm in southern Alberta. “We don’t make enough methane at the moment for viable power generation,” Kewley says. “We will with the next expansion. The plant was designed to expand to 185 mgd, seven times bigger than it is now.” Kewley notes that the University of Calgary is developing fuel cell technology that uses methane gas.
The Pine Creek biogas isn’t wasted: It fuels boilers for process heat and water heating, including in-floor radiant heating in the operations and maintenance building. To save potable water, reclaimed water is used in the plant for purposes that include low-flow, dual-flush toilets. “That’s one thing that is going to happen in the future for wastewater plants,” Kewley says. “It’s definitely on people’s radar. Even community expansions may include ‘purple pipe’ systems for using reclaimed water.”
Once an agreement is finalized with a nearby golf course, about 10 percent of Pine Creek effluent will be reclaimed. “We have a 20-year lease with the City of Calgary for a tree farm on a part of our 340-acre site,” says Kewley. “It uses treated effluent for irrigation, and we’re always open to businesses knocking on the door.”
Biosolids from three wastewater treatment plants are decanted in lagoons and given to farmers through the city’s Calgro program. “We have farmers and ranchers lining up for it,” Kewley says. About 44 million pounds of biosolids are injected annually on 4,200 acres of farmland within a 30-mile radius.
Aesthetics played a big role in plant design. “Many wastewater plants across North America are putting a lot of value and time into architecture to make them look nice to the public,” says Kewley. “We used rock gabion walls, and the buildings are clad in brown zinc, a noncorrosive metal that will last 100 years. We’ve tried to blend in with the neighborhood.” Berms strategically placed around the property help it fit with the surroundings. Outside lighting meets dark-sky standards.
While it sits next to the river, the plant property is still outside the 100-year flood plain. “We have to pump wastewater up 20 feet to the plant,” Kewley says. Excavation was limited during construction, and the plant is built on pilings driven into bedrock to keep it above the flood plain.
The wisdom of that became clear in June 2013, when the worst flooding in Alberta history hit the region. Though the city’s Bonnybrook treatment plant was out of operation for about three weeks, Pine Creek wasn’t affected.
Kewley says the plant’s design demonstrates Calgary officials’ long-term thinking and the innovation found in the wastewater profession. “Processes and technology are changing all the time,” notes Kewley. “Plants are getting bigger and better, and treatment is getting better.”