Colorado facility adds hydroelectric generator to minimize energy costs
North Central Colorado’s Larimer and Weld counties are home to not only sprawling national forests and scenic mountain vistas, but a number of fast-growing urban areas, including Fort Collins, Loveland, Thornton and Greeley. According to the U.S. Census Bureau, the counties’ combined estimated population as of July 2017 was 648,609, up from 125,687 in 1960.
Population growth of that magnitude in so short a time can greatly tax public works systems. The Soldier Canyon Filter Plant, which provides water to parts of Larimer and Weld counties, has expanded numerous times to keep up with the increasing demand, and has significantly improved its energy efficiency with the recent installation of a hydroelectric generator.
The Fort Collins – Loveland Water District, the East Larimer County Water District and the North Weld County Water District—collectively known as the Tri-Districts—built the Soldier Canyon Filter Plant in 1962, shortly after the districts were founded to provide water service to the area for the first time. Located at the base of the Soldier Canyon Dam on Horsetooth Reservoir just west of Fort Collins, the facility originally had a 10-million-gal-per-day (mgd) treatment capacity. Since its construction, its capacity has been expanded several times, and today it stands at 50 mgd.
“[The expansion] is all based on the three districts all needing additional capacity,” said Chris Harris, plant manager for the Soldier Canyon Water Treatment Authority. “There’s been a lot of growth here on the Front Range of Colorado, and so it’s pretty close to every 10 years the plant has expanded.”
The plant performs conventional treatment—coagulation, flocculation, sedimentation, filtration and disinfection. Additionally, it pre-oxidizes incoming water with chlorine dioxide to eliminate manganese, adds soda ash for corrosion control, and adds sodium fluorosilicate (fluoride) to help improve customers’ oral health.
“Like all plants that are expanded multiple times over the years, there are some limitations and some components that we would have constructed differently if they were designed today,” Harris said. “But our plant is very robust, and handles all the water quality challenges very well.”
In June 2018, the Soldier Canyon Filter Plant completed installation of a hydroelectric generator. Custom-designed by Applegate Group, built by Canyon Hydro and installed by Garney Construction, the generator uses the motion of the water flowing into the plant to produce electric power.
“It will offset our electrical costs,” Harris said. “We’ll still pay some money to be connected to the grid, but it will substantially lower our electrical costs, and it’ll pay for itself in about 15 years.”
The generator is one of 35 in the state to be supplied by Canyon Hydro, which preassembled the equipment and supplied it to the utility in a clamshell precast vault with the control system already wired. It produces approximately 125% of the power the plant needs to operate; the excess energy produced is sold back to the local utility for a profit.
“It makes a lot of sense for us from a financial, environmental and power redundancy perspective,” Harris said. “It’s new for us. The other things we do, we’ve been doing for over 50 years, so we’re fairly used to that, but the hydroelectric generator definitely seems unique to us for now.”
The generator’s installation includes space for a second turbine, which may be installed when the facility’s expansion outpaces the single generator’s production capability.
Though they are still getting used to the generator, the Soldier Canyon team is moving on to the next phase in the facility’s evolution: another expansion of its treatment capacity.
“We’re in the design phase,” Harris said. “We’re going to expand the plant to 60 mgd. That’ll begin early next year. The amount of water we’re treating is the main change, due to the increased population.”