The Rollin-Woodstock treatment facility serves a system of sanitary sewers and pumping stations in the Village of Addison and portions of Rolllin and Woodstock Townships, located adjacent to Devil's Lake and Round Lake. In order to reduce biochemical oxygen demand (BOD), suspended solids and ammonia, the new 1.2-MGD plant was designed to operate with an activated sludge process rather than the aerated lagoons that were used in the County's existing 0.65-MGD facility.

The new facility has a hydraulic capacity of 3.0 MGD. In order to conserve costs, many existing structures at the existing plant were renovated for use with the new plant. For instance, the grinder was upgraded to produce finer solids, the air mixing tank is now used for grit removal, and the primary settling tanks are now operated as gravity sludge thickening tanks in the new facility. Two 400,000-gallon earthen aeration ponds and a 2.0 MG flow equalization basin were created within the existing aerated lagoon. An addition was made to the existing control building to provide more lab space, two offices and a lunch/meeting room.

ARCADIS helped the County prepare applications for financing for the project, which was financed through the Michigan State Revolving Fund. The financing package included the refinancing of existing bonds. This project was only the second one statewide to take advantage of this refinancing option. The new plant was completed in 2002 at a construction cost of $5.2 million.