Wastewater Treatment Plant

WASTEWATER TREATMENT PLANT

Telephone:                   978-374-2382
Facility Manager:        Isaiah Lewis, ilewis@haverhillma.gov
Address:                      40 South Porter Street
                                      Haverhill, MA 01835

The Haverhill Wastewater Treatment Plant (WWTP) is located off South Porter Street, along the Bradford side of the Merrimack River, in the southeast portion of the city.  

Wastewater Treatment Staff is responsible for operating and maintaining the City's wastewater treatment plant. The treatment plant provides primary and secondary treatment for the City's wastewater. The plant discharges the treated effluent to the Merrimack River.

The plant became operational in 1977 and has the following facilities:

• Screening
• Grit Removal
• Primary Settling
• Secondary treatment using an activated sludge process
• Disinfection with sodium hypochlorite

Detention time for disinfection is achieved by passing total flow through 1,200 feet of 102-inch outfall pipe followed by 800 feet of 60-inch outfall pipe before entering diffusers that discharges to the Merrimack River.  Primary sludge is processed in gravity thickeners.  Waste activated sludge is thickened in dissolved air-flotation thickeners.  The thickened primary and waste activated sludges are combined and dewatered in centrifuges.

A single pump station pumps all flow from the terminus of the Bradford interceptor to the treatment plant. This station is designed for a peak flow of 60 mgd with 3 pumps in operation and the fourth pump as a standby. Connecting the pump station to the WWTP is a 42-inch force main with a length of approximately 3000 feet.

The Wastewater Treatment Plant is permitted through the National Pollutant Discharge Elimination System (NPDES) click here to view the NPDES permit. The permit expires every five years at which time the City has to apply for a renewal. The current permit was issued on January 1, 2020. The permit establishes the discharge limitations for the plant under the Clean Water Act.

WHAT IS A BLENDED WASTEWATER DISCHARGE?

Blending is an operational strategy for managing high treatment plant flows which occur during major storm events due to infiltration and inflow (I & I) of rainwater into the sewer system. During extreme wet weather events, wastewater becomes a small portion of the total treatment plant flow.  Blending protects the treatment plant’s secondary (biological) treatment process from flows that would damage the process and/or exceed its design capacity. 

During a blending event, all treatment plant flows undergo primary treatment, which consists of screening, grit removal, and settling.  Most of the flow then continues on to the secondary treatment process, where dissolved organic material is removed (oxidized) by bacteria and other microorganisms.  A portion of the flow is routed around (i.e. bypasses) secondary treatment, and then recombines with the main flow prior to disinfection. 

When blending, all flows undergo disinfection, and the treatment plant is still required to meet all applicable regulatory limits in its discharge permit.

For more information on partially treated wastewater click here.