Wastewater Treament Plant

The Keene Wastewater Treatment Plant (WWTP) is owned by the City of Keene and is operated by the City's Department of Public Works. It is a Grade IV secondary treatment, activated sludge facility. Located on Airport Road, behind the Dillant-Hopkins Airport, the WWTP presently treats the domestic and industrial wastes from the communities of Keene, Marlborough, and some sections of Swanzey with a combined population of 35,000. It also accepts septage waste from the local area.

The WWTP is an activated sludge process, with biological nitrification, permitted for the discharge of an average daily flow of 6 million gallons. Peak design capacity is 15 mgd. Treatment consists of grit removal, primary settling, secondary aeration, flocculation, final settling, and disinfection by ultraviolet light. The plant effluent is discharged into the Ashuelot River.

Solids collected from the primary and secondary systems, are thickened and combined then dewatered using belt filter presses.

The City is permitted, through its NPDES Discharge Permit issued by the U.S. Environmental Protection Agency and the State of New Hampshire, to treat and discharge 6 million gallons per day. The actual average daily flow is approximately 3 million gallons per day. Effluent flow to the river must have a monthly average of less than 30mg/L total suspended solids (TSS) and 25 mg/L carbonaceous biochemicaloxygen demand (CBOD). Keene has averaged greater than 95% removal of both of these parameters since 1990.

Above left: Aeration; Above right: Dewatering; Below center: UV disinfection

Links of Interest:
Keene City laboratory
Water Treament Facility
NH DES Water Division

Operations Manager Aaron Costa: 357-8483