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Portsmouth to Build Higher Level of Treatment and Control Sewer Overflows

Release Date: 08/18/2009
Contact Information: David Deegan, (617) 918-1017

(Boston, Mass. – Aug. 18, 2009) – Under a recent settlement, the City of Portsmouth, N.H. will build better wastewater treatment and control sewer overflows.

The agreement is filed as a consent decree in federal court because the City does not currently have the treatment facilities necessary to meet stringent limits in its waste water discharge permit. Also, much of the City’s sewer system is made up of a single set of pipes that carry combined storm water and industrial and domestic wastewater to the treatment plant. These pipes overflow during heavy rainfall, discharging untreated wastewater.

The consent decree requires the City to complete all construction for its “Combined Sewer Overflow” (CSO) control projects, called for in its 2005 Long Term Control Plan, by October 2013. It also requires Portsmouth to submit to EPA by Sept. 1, 2010 a schedule for all facility upgrades and collection system improvements, including secondary treatment and CSO controls, to be incorporated into the decree.

The federal Clean Water Act requires most municipal treatment plants to provide “secondary treatment” for all wastewater. It allows communities discharging to oceans, however, to receive a waiver of that requirement. Historically, Portsmouth has received a waiver. The law has been changed to prohibit waivers for communities discharging to impaired waters even if the community is not causing the impairment. Portsmouth’s current permit requires “secondary treatment.”

Portsmouth’s sewer system, along with many other communities in New England, has a “combined sewer system.” Combined systems carry storm water and industrial and domestic waste water in a single system and were designed to overflow during heavy rainfall. The City has completed a substantial amount of work to separate its system, reducing untreated overflows to waterways by up to 75 percent. The Consent Decree requires the City to implement a number of additional projects and to develop a plan for eliminating its overflows entirely.

“EPA is committed to taking action to bring aging sewer systems into compliance with the Clean Water Act," said Ira Leighton, acting regional administrator for EPA’s New England office. “We are pleased that the City of Portsmouth has agreed to do what is necessary to come into compliance with these regulations.”

The consent decree does not require the City to pay an up-front penalty, but if the City fails to comply with the agreed-upon schedule, penalties could be applied.

More information:
EPA's enforcement of the Clean Water Act in New England (

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