Thirwood Place on Flax Pond in West Yarmouth is a premier senior living community. Coastal Engineering Co. has been providing operation and maintenance for the area’s wastewater treatment plant since 2015. The treatment system consists of an aerobic Rotating Biological Contactor (RBC) and a anoxic RBC. The system has a equalization tank that feeds the RBC’s and then the effluent passes through a clarifier. The system is very efficient at reduces solids and removes total nitrogen which is consistently less than 10 mg/l. Currently, Coastal Engineering performs daily operation and maintenance of the facility. Process control chemicals are dosed from the control building.