Atkins Reservoir

Overview Descriptions
Pre-Trident Ozonation
Improves raw water quality by removal of taste, odor, and color. Additionally, CT disinfection credits can be achieved.

Trident Process
This proprietary process is provided in 3 factory-fabricated steel tank modules, each rated for 0.75 MGD. The trident process utilizes a buoyant plastic media placed within an upflow clarifier / roughing filter. This initial stage is followed by conventional mixed media filtration.

GAC Adsorption
GAC adsorption has been provided in an economical factory-fabricated, gravity flow contractor vessel segmented into 2 separate compartments. The use of GAC preceded by ozone application promotes a biologically active GAC process and provides excellent removal of naturally occurring organics through biodegradation.

The treated water that is produced is very pure and stable with regards to taste and odor-producing organics. Additionally, the improved removal of DOC reduces the water's chlorine demand and reduces the potential for bacterial re-growth within the distribution system.

Chlorine Addition and Rapid Mixing
Chlorine may be added at multiple locations and is followed by a static mixer. Chlorine addition may be for the purpose of maintaining a distribution system residual or may also be utilized to provide the full CT disinfection requirements for a plant meeting the direct filtration criteria.

Chlorine Contact Basin
Primary disinfection to meet the CT requirements, if by free chlorine as an alternate to the plant's ozone system, is provided by the chlorine contact basin, which is a long narrow basin with 5 intermediate redwood baffles. Tank geometry plus inlet flow distribution and baffling is provided to provide a plus flow efficiency of 65┬▒%, which satisfies the worst case CT requirement using chlorine residual of 1.0 mg/L.

Ammonia Addition
Amherst has successfully controlled distribution system trihalomethanes (THMs) and maintained disinfectant residuals by utilizing chloramination.

Clearwell Storage
Flow equalization and backwash water requirements are provided by a 2 compartment clearwell storage arrangements. Each clearwell basin provides 250,000┬▒ gallons of treated water storage.

Treated Water Pumping
Two variable speed vertical turbine pumps are provided, each rated at 1.5 MGD (1,040 gpm).

Treated Water Chemical Addition for Corrosion Control
Prior to entering the distribution system, the corrosivity of the treated water is reduced by adjusting the pH to 9.0 using sodium hydroxide.

Treated Water Fluoridation
Amherst currently fluoridates all of its water supplies.