The Arnold Sewer Treatment Plant was finished in 1985. It is an activated sludge plant using an oxidation ditch and secondary clarifier. The solids are processed by aerobic digesters and sand drying. The liquid is then disinfected and filtered. Disposal is done on-site using a leach field and spray irrigation. The capacity is 170,000 gallons per day (gpd). The average dry weather flow is 70,000 gpd.