Brown and Caldwell to help remove PFAS from Colorado county's water

The South Adams County Water and Sanitation District near Denver is enhancing its water treatment process to meet Environmental Protection Agency (EPA) Health Advisory Levels (HALs) for per- and polyfluoroalkyl substances (PFAS) in drinking water supplies.

Serving more than 67,000 residents in Commerce City, Colorado, and unincorporated areas of Adams County, the District’s water supply primarily comes from 13 groundwater supply wells. Although it continues to meet all federal and state drinking water requirements, the District has been proactively pursuing PFAS reduction strategies since it first discovered a low-level presence of the substance in its water supply through voluntary testing in 2018. Upon discovery, the District stopped drawing from its most impacted wells and has been purchasing additional treated water to blend into its supply to reduce PFAS levels along with optimizing use of its existing granular activated carbon treatment system.

Recently, the EPA lowered its interim lifetime HAL standard for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from 70 parts per trillion (ppt) combined to 0.004 ppt for PFOA and 0.02 ppt for PFOS.

While the District maintains test levels below 70 ppt for PFOA and PFOS, the new HALs are set so low that it is not yet possible to detect the presence of the compounds at these levels scientifically.

“Ever since the District first began voluntarily testing for PFAS, we have been monitoring for these compounds and working to reduce their impact on our customers,” District Manager Abel Moreno says. “The EPA has moved the goalposts, and we are taking steps to reduce the presence of PFAS even further. We are committed to finding long-term, sustainable solutions to offer our community high-quality drinking water.”

To tackle the challenge, the District has hired the environmental and construction services firm Brown and Caldwell, Walnut Creek, California, to design a new 18 million gallon per day ion exchange processor at its Klein Water Treatment Facility. Ion exchange treatment is the most effective technology for removing PFAS and PFOA, consisting of a highly porous resin that acts as a powerful magnet to absorb and hold onto the harmful substances. The new system at the Klein facility will consist of seven ion exchange treatment trains, a 375,000-gallon equalization tank and six vertical turbine pumps to feed the ion exchange trains from the District’s 13 groundwater supply wells.

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Additionally, nine 5-micron cartridge filters will be installed to remove particulate matter in the water before reaching the ion exchange trains, increasing the efficacy of the treatment process.

“We commend the District for taking this important step to achieve a cost-effective, reliable and safe water future,” Brown and Caldwell Client Manager and Process Lead Laurie Sullivan says. “PFAS is a nationwide challenge, and the District is working diligently to put numerous measures in place to monitor and treat contaminants to maintain regulatory compliance.”

Deemed “forever chemicals,” PFAS is a group of human-made chemicals used in many applications, including stain- and water-resistant fabrics and carpeting, cleaning products, paints and firefighting foams. PFAS are resistant to grease, oil, water and heat and may enter water supplies from landfills, the use of firefighting foam, industrial sites and wastewater treatment plant discharge, Brown and Caldwell says. 

Scheduled for completion by the end of 2026, the new ion exchange treatment facility will provide a peak combined capacity of 26 million gallons per day.