The City's Water Treatment staff are committed to providing clean, safe, potable drinking water to the City's residents and utility customers in adequate quantities to meet the needs of our customers.
If you are interested in a water treatment plant tour, please see the following documents:
Water Treatment Facilities
Thornton Water Treatment Plant
Wes Brown Water Treatment Plant
Thornton Water Treatment Plant
Plans to construct the new Thornton Water Treatment Plant (TWTP) began in 2016. It was finished and began producing water for the public in late September 2020. TWTP has a maximum capacity of 20 Million Gallons per Day (MGD) and replaces the original plant built in 1956. TWTP uses proven advanced technology to treat a variety of source waters. It is explicitly designed to address taste and odor issues while efficiently removing pathogens and other contaminants.
TWTP treats waters from Standley Lake (SL) and East Gravel Lakes (EGL). There are significant elevation differences between the plant and its two source waters. Water from SL flows in by gravity, while water from EGL must be pumped uphill 320 feet over several miles. An oxidant is added to the raw water to remove common dissolved metals like manganese and iron. The two sources are blended depending on water availability. Coagulants are then added. These chemicals cause microorganisms and small particles suspended in the raw water to stick together and grow into bigger particles that settle out later in the process.
Two 350,000-gallon Flocculation Basins use horizontal rotating paddles to mix the water gently. The mixing encourages the particles, now called “Floc,” to grow in size. As the water progresses to each mixing chamber, the paddle area and speed reduction calm the water currents, allowing the Floc particles to settle out in the next step.
Two 440,000-gallon Sedimentation Basins allow the large Floc particles to settle out by gravity. These basins are fitted with vertically inclined plate settlers, which significantly improve the settling rates of the Floc. This “settled” water then moves to the next step of the process: Ozonation. Meanwhile, the Floc that settled out accumulates into a sludge layer on the bottom of the basin, which is removed by a pair of Track-Vac vacuum collectors that travel the length of the basins. The sludge is piped down to sludge handling lagoons at Wes Brown Treatment Plant, where the solids collect at the bottom for later removal, and any water is recycled back into the Gravel Lakes.
A 125,000-gallon Ozone Contact Chamber (OCC) is where Ozone, a powerful oxidant, is added. Ozone breaks down taste, odor, and other organic compounds into a digestible form of carbon consumed by naturally developed biology on the biofilters.
Six 634-square-foot Biofilters are the heart of the plant. Each filter has five feet of Granular Activated Carbon (GAC) on top of one foot of fine sand through which water passes by gravity. GAC is porous, allowing naturally occurring bacteria to form on a large surface. These naturally developed microbes remove organics, metals, and other contaminants. The clean water then continues onward for disinfection. The filters typically run from 96 to over 400 hours, depending on the season, source water, and production demands. When a filter reaches the end of a filtration cycle, clean water flows reverse through the filter media and aeration to remove accumulated material in a Backwash (BW) process.
Backwash waste is piped down to Wes Brown Treatment Plant lagoons for processing.
The clean water used for the backwash is a 430,000-gallon Backwash Supply Basin, filled with water diverted from the filter effluent flow before disinfectant addition, is the clean water used for the backwash. Most filtered water proceeds to the 1,090,000-gallon Disinfectant Contact Chamber (DCC).
The disinfectant is added at the beginning of the DCC. The water travels in a maze-like serpentine pattern. This ensures adequate contact time to disinfect any remaining harmful pathogens. At the end of the DCC, the disinfectant is converted to chloramines, a more stable disinfectant that provides further protection through the distribution system tanks and piping. Final pH adjustments can be made to optimize corrosion control for lead and copper mitigation and enhance chloramine stability in the nearly 650 miles of pipes that make up the city’s distribution system connecting the treatment plants to each of the city’s customers.
Wes Brown Water Treatment Plant
The Wes Brown Water Treatment Plant, a 50 million-gallon-per-day facility, uses advanced water treatment processes, including state-of-the-art ultrafiltration (UF) membranes, to remove suspended solids in the source water down to .04 microns. Along with pre-treatments in the reservoirs, vigilant environment monitoring, and many other technologies, the process provides pathogen-free, high-quality drinking water.
Clarifier—After chemicals are added to the raw water supply, four clarifiers help settle sludge (chemicals attached to dirt particles) to the bottom. In contrast, cleaner water flows to the surface and is carried to the ultrafiltration membranes.
UF Membrane - The Wes Brown Water Treatment Plant’s state-of-the-art membranes filter the clarified water to further clean it of pathogens and viruses. Placed end to end, there are over 14,000 miles of membranes in the treatment plant!
Pump Station - The final treatment process is disinfection. The City of Thornton uses Chloramines (Chlorine and Ammonia) to maintain a disinfection level in the distribution system. The Wes Brown Water Treatment Plant is also home to a 60 million gallon per day pump station, which pumps finished water to the distribution system for customer use.
The city operates the Wes Brown Water Treatment Plant and the Thornton Water Treatment Plant, both 20 million gallons per day conventional plants with UV disinfection.
The City’s Water Treatment staff are committed to providing clean, safe, potable drinking water to the city’s residents and utility customers in adequate quantities to meet the needs of our customers.