Colorado utility removes PFCs from well with Xylem’s ion exchange system

Perfluoro compounds (PFCs), which are suspected carcinogens, are a growing concern for communities and a challenge that many water utilities need to address. When the Stratmoor Hills Water District detected PFCs in a seasonal well, the utility partnered with Evoqua, a Xylem company, to find a cost-effective solution. The utility’s innovative new system, using selective single-use ion exchange resin, now removes PFCs to below detection limits.

The small unincorporated township of Stratmoor Hills is located in the foothills of Cheyenne Mountain in Southern Colorado Springs. It offers its residents stunning views, a lively cultural mix, and a convenient commute to the Fort Carson U.S. Army installation, making it a popular place for military families to live.

The community’s water security is the responsibility of the Stratmoor Hills Water District (SHWD), which oversees a combination of surface and groundwater sources. Concern about PFCs began in 2016, when the U.S. Environmental Protection Agency (EPA) issued a health advisory for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in drinking water.

The EPA’s advisory tightened limits for these two PFCs from previous levels of 400 parts per trillion (ppt) of PFOA and 200 ppt of PFOS to 70 ppt for single or combined concentrations.

Local aquifer contaminates seasonal well with PFCs

The EPA’s new lower limits for these suspected carcinogens coincided with the discovery of PFC contamination in the Colorado Springs area’s Widefield Aquifer. It was alleged and widely reported that the contamination originated at Peterson Air Force Base, which used foams that contain PFC chemicals in firefighting training. This caused the State of Colorado to add a third PFC, PFHPA, to the EPA’s combined 70 ppt limit.

The lower limits and reported aquifer contamination led SHWD to evaluate its seasonal wells, which draw from the Widefield Aquifer and are used to supplement surface water sources during the summer. One well was found to be above the new EPA limit.

“Up until the state added PFHPA to the restriction, our wells were all under the limit,” says Kirk Medina, District Manager for SHWD. With the change in regulation SHWD immediately went in search of a treatment solution.

PFC treatment with selective single-use ion exchange resin

To meet the treatment requirements for all three chemicals, Xylem’s Evoqua company proposed an innovative system utilizing selective single-use ion exchange (IX) resin. Evoqua has pioneered the use of selective IX resins, which have been extensively used in California and Massachusetts for removing perchlorate, a contaminant with similar properties to PFAS.

The success of an earlier pilot test at a neighboring water district gave the team confidence that Evoqua’s ion exchange solution would work as a first full-scale installation for treating PFOS, PFAS and PFHPA in the field. The operating numbers also gave the solution a compelling advantage. The installation footprint was small enough to be portable if SHWD needed to move to a different well site.

With single-pass instead of regenerable resin, operating costs and on-site materials would be minimized over a 10-year lifetime. In addition, the ion exchange resin was more suitable to the seasonal use of the well.

Based on the test results and the business case, SHWD decided to request a production-scale system from Evoqua.

“When we approached the Air Force and told them that we preferred the single-pass ion exchange system that Evoqua was offering, they were open to that, and it was ordered,” says Medina.

Close collaboration between the Air Force, SHWD and Evoqua resulted in fast delivery and setup. SHWD staff and the Air Force’s contractor worked together to pour the concrete pad, make plumbing modifications, and install the system so that it could treat the contaminated well and be moved to other sites if needed.

Removal of PFCs to levels below detection limits

With the new ion exchange system, Stratmoor Hills Water District was able to recover potable water from a PFOA/PFOS-contaminated well and distribute it to municipal customers.

Evoqua’s ability to respond with a breakthrough application of ion selective IX resin helped Stratmoor Hills Water District solve an urgent PFC contamination problem and meet its customers’ drinking water needs.

The finished configuration includes four vessels that can be operated in single- or two-pass configuration. It processes a flow of 350 gpm and occupies a footprint of 200 sq/ft.

“It’s been fantastic ever since it went online,” says Medina. “I like to say that it removes all of our PFCs to levels below detection limits of 2 parts per trillion … in other words, pretty much nonexistent.”

With the Evoqua system in place, SHWD not only met their goal for PFC removal but exceeded the EPA standards.

“We were fortunate that Evoqua provided us with options,” says Medina. “We’re also grateful that Evoqua was able to expedite delivery so we could meet our production needs. And our staff appreciated the training Evoqua provided. It looks like it’s going to be a very cost-effective solution for addressing this problem that was a big concern to the community.”

Stratmoor Hills expands PFC treatment

Following the successful treatment for the seasonal well, Stratmoor Hills Water District has now expanded its drinking water treatment for PFCs with a full-time, permanent facility. The new system uses cartridge, ultraviolet and ion exchange filtration to provide up to 1.1 million gallons of treated water per day to Stratmoor Hills residents.