Frankfort Water Treatment Plant Disinfection and Chemical Feed System

Constructed in 1974 and located in Kentucky's capital, the Edwin Keith White Water Treatment Plant, has a treatment capacity of approximately 18 MGD. The facility is conventional in design with traditional flocculation, sedimentation, filtration, and chemical feed processes. The Frankfort Plant Board (FPB) hired GRW to evaluate and design improvements for all of the chemical feed systems.

As a result of the evaluation, GRW recommended the replacement of all chemical piping, equipment, and storage facilities. In addition to these constructed improvements, a sulfuric acid feed system for pH adjustment was designed. All chemical feed facilities were sized for a future treatment capacity of 27 MGD. The bulk liquid chemical feed facilities largely consisted of 6,200 gallon fiberglass bulk storage tanks, polyethylene day tanks, magnetic drive transfer pumps, peristaltic tube chemical feed pumps, various piping materials, and associated instrumentation.

On-site generation of 0.8% sodium hypochlorite (NaOCl) was selected for disinfection in lieu of traditional chlorine gas utilization. On-site generation of chlorine utilizes salt (sodium chloride), water and electricity to create a low concentration chlorine solution. The process was selected due to the high safety risk factor associated with chlorine gas utilization. Two 1,500 lb./day NaOCl generators were installed.

The disinfection application locations in the treatment process were also changed to better comply with the Federal Safe Drinking Water Act Amendments for Stage 2 of the Disinfectants and Disinfection Byproducts Rule. Historically, the FPB has pre-treated with chlorine to obtain the required disinfection time and concentration values. Since the FPB converts chlorine disinfection from free chlorine to chloramines by utilization of ammonia, disinfection byproducts have not been a compliance concern. The new improvements will now minimize pre-treatment disinfection and apply greater disinfection post-filtration, which will minimize the exposure of chlorine to microbials and minimize the risk of disinfection byproducts in the water quality.

GRW also designed a new building and a building addition as part of the project. A new disinfection facility was constructed to house the process equipment for the sodium hypochlorite generation system, and a filter/chemical feed building addition accommodated housing of the new chemicals. As a part of the design, common chemical containment areas for acidic and basic materials were separated for safety reasons.

Sustainable design features include architectural skylights and wall panels for natural lighting in the new chemical feed building. In addition, the power rectification units, which provide the correct power for the generation equipment, produce heat during the conversion. This byproduct heat energy is utilized during the colder months to warm the facility, and is distributed throughout the building by thermostatically controlled fan and louver units.

The Frankfort Plant Board and GRW were honored to receive an American Council of Engineering Companies of Kentucky Engineering Excellence Honor Award for this innovative project design.