Aerial view of the Warren, Maine lagoon system. Photo courtesy of Woodard and Curran.

Lagoon Systems In Maine 

Systems In Maine

An Informational Resource for
Operators of Lagoon Systems

Mars Hill Wastewater Lagoon System - Mars Hill  Maine. Photo Courtesy of Wright-Pierce Engineers.
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North Berwick Sanitary District


North Berwick Sanitary District

The North Berwick Sanitary District has achieved their goal of improving the water quality of the Great Works River through the construction of a wastewater treatment facility for the Town of North Berwick. The total project included the construction of 38,000 feet of sewer and force main, seven pump stations, and a new wastewater treatment facility.

     Prior to construction of the new sewer system and wastewater treatment facility, untreated sewage from the village of North Berwick was discharged to the Great Works River creating nuisance and public health concerns. Of particular concern were the adverse effects these raw sewage discharges were having on the downstream impoundment of Leighs Mill Pond.

     After careful evaluation of several treatment alternatives, Wright-Pierce selected the aerated lagoon treatment process with seasonal discharge to the Great Works River. This was found to be the most cost-effective means to provide the required high level of treatment and to protect the river and downstream impoundments.

    Treatment of wastewater in lagoons is one of the oldest, simplest and most reliable treatment processes. Wastewater entering the lagoons is stabilized or treated by several natural processes. Heavier solids settle to the bottom where they are decomposed by bacteria. The lighter material is broken down by bacteria in suspension. The large lagoon volume and corresponding long wastewater detention times provide a high level of treatment. However, even this highly treated effluent contains certain plant nutrients that can contribute to algae blooms downstream.

   To address these and other concerns, Wright- Pierce incorporated several unique and innovative design concepts in the new treatment facility including seasonal discharge and hydrograph release (plant discharge correlated to stream flow). North Berwick is one of the first large scale operating seasonal discharge treatment facilities in the state. The treatment facility includes a 38-million gallon storage lagoon that allows storage (zero discharge) of treated sewage during the summer months of the year. The lower river flows of the summer, combined with the high water temperatures and long sunny days promote algae growth during this period when discharge from the treatment facility will be eliminated completely. During the higher river flows of the winter and spring, discharged nutrients are greatly diluted and more readily flushed through Leighs Mill Pond.

    To provide the needed air for the treatment lagoons, Wright-Pierce incorporated a new "state- of-the-art" aeration system. The aeration system consists of fine bubble porous plate diffusers that rest on the bottom of the lagoons. The system was selected for its comparatively high efficiency, low maintenance, flexibility and reliability.

     The new treatment facility and sewer system represents a major step in restoring the natural water quality of the Great Works River and Leighs Mill Pond. Initial plant start-up occurred in February 1987. A combination of state, federal, and local funds were used to finance the project with a total construction cost of $4.8 million



North Berwick Maine

Design Flow: 0.230 MGD
Peak Flow: 1.150 MGD
Design BOD Load: 643 pounds per day
(38% Industrial, 62% Municipal)
Design SS Load: 708 pounds per day
Total Lagoon Volume: 45.6 MG
Design Detention Time: 122 Days


Flow Schematic

North Berwick Maine

aerated lagoons
click the image above to enlarge


Lagoon Specifications

North Berwick Maine

Lagoons No.1 No. 2 No. 3 Storage
Volume 3.5 MG 1.8 MG 1.8 MG 38.3 MG
Aeration Fine Bubble Fine Bubble Fine Bubble None

Total lagoon acreage is 10.9 acres or 474,804 square feet. Facility has (4) 25 horsepower blowers. Facility has a total of 3.5 acres aerated. Aerator manufacturer is Environmental Dynamics, Inc. Aerator model is the Reef I unit. Lagoons have a total of 106 diffusers.


System Information

lagoon aeration

Design Flow 0.023 MGD
Actual Flow 0.095 MGD
Discharge To Great Works River
Year Built 1985
Design Engineers Wright Pierce
Septage Received No
Collector System 11 miles of gravity sewers, 146 manholes,  3 pump stations
Staff Size 3 Full Time
Number of Users 475
Billing Software User Developed
Comments Plant operates in hold and release mode. No discharge from May 31st to October 1st. Limited to 0.10 MGD from January 1st to March 15th.


Bridge Construction Corporation
Augusta, Maine

S.E. MacMillan Co., Inc.
Bangor, Maine

P. Gioioso & Sons, Inc.
Boston, Massachusetts


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