Cottage Grove Municipal Treatment System Removes PFAS Compounds From Well Water Using Granular Activated Carbon

Located in the Twin Cities metro area, the city of Cottage Grove, Minnesota, needed to increase the capacity of its drinking water system. To meet demands for compliant water two additional wells were equipped with treatment systems designed to reduce PFAS. The city contracted consulting firm Stantec to provide engineering services for the design, during procurement, construction of the facilities and site infrastructure for the dual media granulated activated carbon (GAC) and/or Ion Exchange (IX) equipment systems.

In order to optimize operation expenditure and achieve a lower total cost of ownership for pumping and building requirements, an analysis was conducted considering the dual media capability. It was determined that the overall pressure drop should not surpass 3 pounds per square inch (psi) when media is not present. Additionally, the height of the 12-1340 vessels should not exceed 23 feet and 4 ½ inches. To accommodate the expansion of the carbon media during backwash of the GAC, the sidewall of the vessels was designed to provide sufficient space for the required bed expansion for the specified media.