Filtration Plant

Background

The original Kennebunk, Kennebunkport, and Wells Water District filtration plant was constructed in 1913, many decades before other water utilities in Maine began to filter their surface water. The facility is specifically designed to remove color and turbidity contained within Branch Brook, the District’s primary source of water. The treatment process utilized for removing impurities in the water is classified as conventional filtration.

The initial brick filter building still exists and houses chemicals for disinfection. Over the years, several significant upgrades have been made to the facility for increasing the production rate, improving water quality, improving efficiency in operations and for compliance with drinking water regulations. For example, in 1947 modern chemical mixing and settling basins were added. Rapid sand filters, a clearwell, and laboratory were constructed in 1955. Additional filtration was incorporated in 1980 with a traveling bridge ABW system. Most recently, the District completed building improvements for the addition of fluoride and ammonia.

The Process

Raw water pumps lift water from an impoundment along Branch Brook into a serpentine channel, where chemicals are introduced to promote coagulation. This is where microscopic particles (consisting primarily of color, turbidity and other contaminants) bond together and become larger as the water passes through flocculation chambers with slowly revolving paddles. The flocculated particles then settle out to the bottom of twin sedimentation basins. All settled residuals collected from the sedimentation basin are concentrated and managed for reuse as a topsoil additive. The water is then filtered to remove any remaining particles that did not settle out. Disinfection is achieved through chlorination in a clearwell. Final chemical additives for disinfection, corrosion control and fluoridation are introduced to the finished water prior to the water being pumped into the distribution system. Daily water production can vary from less than 2 million gallons per day (MGD) during the winter months to over 6 MGD during the peak demand tourist season.

Electromechanical Equipment

The instrumentation and controls housed within the treatment plant are state-of-the-art and alert operators to any trouble in the process train. Real-time information for many physical and chemical parameters is available to an operator through a Supervisory Control and Data Acquisition (SCADA) system. The District has upgraded to premium efficient motors, variable frequency drives, high efficiency lighting, and other electrical equipment to save on energy costs.

Plant Staff

The filtration plant is operated by an experienced group of State Board certified water operators. (See 2004: A Year of Many Successes for more information on our talented plant staff) Due to the sophistication of operations and the rapid changes in source water chemistry, the facility is staffed at all times while water is being produced.