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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Wastewater Engineering




  In 1990, the Town of Thomaston initiated a wastewater system improvement program, the
essence of which was to improve the water quality of the St. George River by the elimination of combined sewer overfIows (CSOs) in the sewer system and to improve the compliance record of the treatment facility. The Town began an aggressive sewer replacement program in an effort to eliminate the CSOs. The Town retained Wright-Pierce to conduct an evaluation of the existing treatment plant to determine the scope of work necessary to upgrade the plant to meet the current and future needs of the Town.

   In 1992, the Town determined it was in its best interest to construct a completely new treatment facility. The Town and the Maine Department of Environmental Protection (DEP) agreed to evaluate alternatives that would eliminate the existing discharge to the St. George River. The St. George River is a very productive shellfish area, and by eliminating Thomaston's wastewater discharge, much of the area previously closed to shellfishing could be opened. It was determined that complete elimination of the river discharge was not economically feasible.

    The Town and the DEP worked together to develop an alternative that fit within the available funding and would utilize land application of treated effluent for as much of the year as possible (May through October) and discharge to the river only in the months of January, February and March when much of the river is typically frozen and less accessible for shellfishing. The total area with suitable soils for land application was limited at the proposed treatment site, however those soils present would allow a spray application rate of three inches per week (twice the typical rate in Maine) which made the alternative feasible. This alternative would ultimately allow those areas of the St. George River currently closed to shellfishing to be opened for approximately nine months each year.

    By the end of 1997, the new pumping stations began transporting Thomaston's wastewater to the new treatment facility culminating a 7-year process to upgrade their wastewater collection system and replace their 30-year old treatment plant.

New Facilities

    In 1991, the Town began a sewer replacement program to reduce the amount of non-sanitary (stormwater and groundwater) flows in their sanitary sewer system. By the end of 1997, the Town had replaced approximately 36,500 linear feet of gravity sewer pipe and associated sewer services to each building, and installed five new pump stations with approximately 7,100 linear feet of force main pipe. Through this effort, the Town has eliminated all of its CSOs and no longer discharges untreated wastewater to the St. George River during rainstorms.

    The new wastewater treatment facility also went on-line at the end of 1997. The treatment facility consists of three aerated facultative treatment lagoons constructed in series with a total capacity of 21 million gallons. The treatment lagoons are followed by a storage lagoon with a capacity of 36 million gallons. The facility is designed to treat an average daily flow of 427,000 gallons per day. Aeration is provided to the treatment lagoons via three blowers, air distribution piping, and 98 fine-bubble tubular membrane diffuser assemblies.

    The treated effluent from the lagoons is disposed of in one of two ways. In January, February and March the effluent is disinfected with sodium hypochlorite and discharged by gravity through 7, 100 linear feet of pipe to the St. George River via the outfall pipe at the old treatment plant. From mid may through October, the effluent is land applied by a spray irrigation system consisting of two 75 Hp spray pumps, approximately 26,000 linear feet of distribution piping, and 130 spray nozzles. The land application area is divided into five fields, each consisting of approximately ten acres. The effluent is applied to one field at a time, with each field being used one day each week. Between the river discharge period and the land application season, the treatment lagoon effluent is stored in the storage lagoon. The 78-foot x 40-foot operations building at the treatment facility includes a control room, laboratory, blower room, chemical room, pump room and a garage.


    The total cost of the project, which began in 1991, was $12.2 million, including construction, land acquisition, administration, and technical services. The total construction cost was approximately $8.5 million. The project was funded by state and federal grants and loans from the Department of Environmental Protection (DEP), the Rural Utility Service (RUS), and the Maine Municipal Bond Bank (MMBB) as summarized below.

Maine DEP:

Grants $5.1-million

Loans $2.35-million


Grants $1.26-million

Loans $2.74-million


Loan $0.75-million





Lagoon Specifications

Lagoons No.1 No.2 No. 3 Storage
Volume 10.5 MG 5.25 MG 5.25 MG 36 MG
Lagoon Size 600' x 240' x 15' 350' x 240' x 15' 350' x 240' 15' 960' x 370' x 20'
Lagoon Acreage 3.38 acres 3.3 acres 3.3 acres 8.2 acres
Aeration Fine Bubble Fine Bubble Fine Bubble None
Number of Units 70 16 12 None

Lagoon acreage including berms is 25 or 1,089,000 square feet. Facility has (3) motor blower sets, all 25 horsepower driving 350 SCFM positive displacement blowers. One has an Allen Bradley VFD. Aeration system manufacturer is Environmental Dynamics, Inc and diffuser model is the FlexAir.



System Information

Design Flow

0.430 MGD

Actual Flow

0.270 MGD

Discharge To

Winter-St. George River; Summer to Land Application

Year Built


Design Engineers


Septage Received


Collector System

11 miles of gravity, 355 manholes, 5 pump stations

Staff Size

Two Full Time, 1 Part Time

Number of Users

800 Services plus Maine State Prison


Seasonal (Jan.-Mar.) river discharge and land application May-Oct., to a 50 acre spray area. The Thomaston Town Forest Trail System, a section of the Georges Highland Path, begins at the treatment facility.


Process Flow Schematic

click on schematic for larger size


Basic Design Data

Ship Street Pump Station
A. Influent Pumps
Type: Submersible
Number of Pumps: 2
Capacity: 1700 gpm @ 137 feet TDH
Motor: 100 Hp

B. Mechanical Bar Screen
Bar Spacing: 1/2 inch
Drive Motor: 11/2 Hp


Wastewater Treatment Facility
A. Treatment Lagoons
Type: Aerated-Facultative
Design Average Daily Flow: 0.427 mgd
Influent BOD: 885 lbs/day
Number of Cells: 3
Total Lagoon Volume: 21 million gallons
Liquid Depth: 15 feet (max), 12 feet (min)

B. Aeration Equipment
Type: Positive Displacement
Number: 3
Capacity: 3 70 SCFM each
Drive Motor: 25 Hp
Type: Fine-Bubble Tube Membrane

C. Storage Lagoon
Number of Cells: I
Storage Period: April 1 - May 15, Nov I - Dec 31
Total Lagoon Volume: 36 million gallons
Maximum Liquid Depth: 20 feet
Aeration System: None

D. Disinfection
Chemical Used: Sodium Hypochlorite
Application Points: Effluent Piping / Operations Building Disinfection 
Period: Jan I - March 31
Chemical Storage: 2-550 gallon tanks

E. Spray Irrigation
Typical Spray Period: May 15 - Oct 31 (24 weeks) Number of Fields: 5
Size of Fields: 10.2 acres each
Application Rate: 3 inches/week
Spray Pumps
Type: Horizontal Split Case
Number: 2
Capacity: 1050 - 1350 gallons/minute


Operator Name John Fancy
Facility Address Dover Road
  Thomaston, Maine 04861-0299
Telephone (207) 354 - 2131
Fax (207) 876 - 2137


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