$4.2 Million Dollar Phase II Merrimack Wastewater Treatment Facility Upgrade is complete!

Merrimack Public Works

Why Phase II?

The Merrimack Wastewater Treatment Facility (MWTF) became operational on May 5,1970 and construction was funded through Federal and State grants, with the community sharing in 5% of the costs. Since then, several focused upgrades have been completed including the recent Phase I upgrade that was completed in 2007.  Funding for the project is through sewer user fees, not taxes.
Much of the original equipment is still in operation, 42 years later, and has reached the end of its useful life. Replacing this equipment, in Phase II, is necessary to provide continued uninterrupted service to the community as well as to maintain compliance with the Town’s EPA discharge permit.  By upgrading the facility over the next several years (including a proposed Phase III project) the Town of Merrimack will renew its commitment to protecting the environmental quality of the Merrimack River and providing continued excellent service to the community while meeting regulatory requirements.

What Is Phase II?

The goal of Phase II at the MWTF is to replace old and inefficient equipment and add some new equipment, thereby realizing energy savings resulting in reduced costs to operate the MWTF and meeting the requirements of the Town's EPA discharge permit. The following is a list of equipment replacements or additions:

  • Replace two primary clarifier effluent pumps with three smaller more efficient pumps to serve current flows while meeting future needs
  • Replace two aeration blowers with two new high efficiency blowers
  • Replace diffuser membranes that will increase oxygen transfer efficiency in the aeration tanks
  • Seperate primary and secondary sludges to prevent rerelease of phoshporus
  • Upgrade the SCADA (Supervisory Control and Data Acquisition) system with new equipment. This system provides computerized information and alarming while allowing us to operate a one shift operation, a savings of five positions over a 3 shift operation
  • Plant Water System Replacement. This equipment processes  treatment plant effluent that can be  used as wash water for various equipment and in our yard wash down hydrants
  • Add a new dechlorination facility to replace a staff built facility which has limited capacity. This system is necessary to achieve permit compliance under all circumstances
  • Replace original plant lighting with new, more efficient lights and fixtures as recommended in an energy audit in all of our buildings

When Will Phase II be completed?

The Phase II project is complete and we are averaging 15% energy savings.

How Will This Project Be Funded?

Funding for this project is through a low interest loan from the State Revolving Load Fund.  The project is paid for through sewer user fees:  not taxes. 

How Can I Get More Information?

You may contact Jim Taylor, Assistant Public Works Director / Wastewater at 420-1620 from 7 am to 3 pm Monday through Friday.  
Remember; even if you aren’t connected to the sewer system all septic tanks that are pumped in Merrimack come to the MWTF for treatment.