Introductions
Today, clean water plays a vital and indispensable role in the lives of Maine’s people, industry, and our environment. Since the introduction of the Clean Water Act in 1972, we have recognized that clean water is a resource that must be valued and protected. Senator Edmund Muskie, a Kennebunk resident, championed that Act and was instrumental in its passage into law.
The Kennebunk Sewer District was established in 1955 with the purpose of preserving and protecting the public health and welfare of the citizens of Kennebunk and to protect the waters of the Kennebunk and Mousam Rivers. For that purpose, the Maine Legislature granted the District a charter to serve within the boundaries set forth and described in the charter with the authority to establish rules and regulations to govern the operation of its wastewater system and to establish and collect fees from the users of that system.
Admirals Way Pump Station 1
Collection and Transportation
The first step in treatment is the collection and transportation of sanitary waste to the Wastewater Treatment Facility on Water Street. To accomplish this, the District has constructed over 36 miles of gravity sewers, 11 miles of force mains, and 29 pumping stations. Because the treatment plant is located close to the downtown, the wastewater needs to flow by gravity to a pumping station that then pumps it to a higher elevation. The topography in Kennebunk requires more than typical number of pumping stations be constructed to collect the wastewater. In one case in the Lower Village area, wastewater needs to be pumped through five pumping before arriving at the Treatment Plant.
Wastewater Treatment Processes
The District Treatment Facility is a 1.3 Million Gallon per Day (MGD) plant consisting of physical, biological and chemical treatment units located a 71 Water Street. Originally constructed as primary treatment facility that included waste settling and disinfection, the plant has been reconstructed a number of times to provide higher and more dependable levels of treatment.
The existing facility consists of the following main treatment units in order of treatment:
Headworks: Provides grit and screenings removal and pumping to the rest of the treatment units;
Primary Clarification: Allows for solid and liquid separation;
Biological Treatment Units: Rotating Biological Contactors grow beneficial bacteria at breakdown the waste into food for the bacteria transforms the waste into form that can be separated from the liquid in the next phase;
Secondary Clarification: This post biological treatment allows for quiescent conditions that allow the waste to settle to the bottom of the tanks for pumping to dewatering units while the separated liquid moves to the final treatment units;
Disinfection: The liquid that separates from the solids in the secondary clarification process is then disinfected with a form of Chlorine and then the chlorine is removed from the final effluent before being discharged to the Mousam River, and;.
Sludge Disposal: Settled solids or sludge at the bottom of the primary and secondary clarifiers are pumped to Sludge dewatering units that remove water from the waste. The resulting sludge is deposited in containers and shipped to a licensed composting or digesting facility for use as a soil amendment.
Future Needs
The existing treatment facility relies on biological treatment units that will not be able to meet anticipated nutrient removal requirements moving forward. The existing biological units, Rotating Biological Contractors (RBCs), are now beyond the end of their 30-year life expectancy and the District has decided that the RBCs will be replaced with a biological system that will serve the District’s treatment needs into the future.