Water Treatment

Mission: To convert ground water to a potable water supply that meets or exceeds the Department of Environmental Protection Agency standards, Department of Health standards and the standard established by the Safe Drinking Water Act of 1974.

Operations: The Water Treatment Plant is licensed to operate under specific guidelines established by the Environmental Protection Agency and the State of Tennessee. The plant is operated by Tennessee licensed Water Plant Operators with a Grade III license or higher.

Capacity: The Water Treatment Plant is capable of producing three (3) million gallons of potable water per day (MGD.) City customers, on average, require approximately 1.8 MGD to meet their needs. Currently, the average person uses about 80 gallons of water per day. The current available “Elevated Storage” is 2.4 million gallons of potable water.

THE PROCESS

Water Source & Transmission The source of our city’s drinking water is ground water that stems from underground aquifers located 700 to 800 feet below the earth’s surface. The ground water source is pumped from a depth of approximately 750 feet through underground transmission lines to the City Water Treatment Plant. There are a total of four (4) ground water wells/pumping stations that are operable. Most ground water contains metal impurities, such as iron and manganese. Ground water, here in the City of Ripley, Tennessee, has an initial iron residual of around 7.0 mg/l with a pH Level of 6.4, but has no problem with manganese. The City Water Treatment Plant performs a series of operations that filters out the metal impurities to make the City Water attractive and drinkable.

Aeration The first step in the treatment process is to increase the oxygen level in our water supply (source water) by using a Forced Draft Aerator with a capacity of 2,100 gallons per minute. This component of the process allows the source water to be fed into the top tray of the Aerator, and sprinkled over PVC slats while air is forced upward.

Coagulation The second step in the treatment process is the introduction of coagulant chemicals that converts the dissolved iron into small “pin head size” particles. We add Calcium Hydroxide (Lime) to condition the water, meaning raise the pH Level. The reaction is instantaneous and occurs in the Flash Mixing Basin that has a capacity of 3,000 gallons per minute. Good practice proves that the best iron removal is obtained at a pH of 8.0 Standard Units.

Disinfection Chlorine is also added, during the Flash Mixing Process, as a purifying agent prior to the Filtration Process. It can also be added after the Filtration Process, if needed. Federal drinking water regulations require that minimum disinfection standards be met at all times before the water can be delivered to the public. Holding the processed water in our Clear Wells (Underground Storage) provides sufficient time for final chlorine disinfection to make sure that all possible disease causing bacteria is killed by the chlorine before the water is pumped to the customer for consumption.

Flocculation The third step in the treatment process is called Flocculation, which occurs in the center cone of the Primary Clarifier. This is a physical process in which the tiny pin head size particles created in the coagulation process are gently mixed. As they collide, they stick together forming larger and larger particles.

Sedimentation The enlarged particles, now referred to as Floc, are transferred to the bottom of the Primary Clarifier. The velocity of water flow in the Primary Clarifier is reduced which allows the Floc to gradually sink to the bottom of the basin. This process generally takes about two hours. Settled Floc, referred to as sludge, is drained off into our sewer collection system. When the water in the Primary Clarifier is relatively free of Floc, (it having sunk to the bottom,) it passes through tube settlers and overflows into a collection flume directing water to six (6) gravity fed filters with a capacity of 2,160 gallons per minute.

Filtration The forth step in the treatment process is gravity filtration, which consist of six (6) filters made up of Anthracite Coal, Coarse Sand, Dense Sand, and Coarse Gravel. The Filtration process ensures that any potentially harmful microorganisms and particulate matter are removed.

Backwash The filters are backwashed to remove microorganisms and particulate matter captured during the filtering process. The backwash water is discharged into our sewer collection system. The filters have a service life of 10 years or more when properly maintained.

Fluoridation Program The City of Ripley Water is enriched with fluoride to help prevent the development of tooth decay. Following the water filtration process, it is collected in an under drain pipe system where fluoride is injected as the water is directed to the Clear Well (Underground Storage).

Storage The water is then pumped from the underground storage to the overhead tanks within the distribution system for our customers’ usage. The current available “Elevated Storage” is 2.4 million gallons of potable water.

Operations and Maintenance The Water Plant Chief Operator and Plant Supervisor are responsible for the day-to-day operation of the plant. The Water Plant Chief Operator contains a Grade III or higher water treatment license from the State of Tennessee.

They assure computerized controls are functioning as intended, maintains all mechanical equipment, maintains chemicals and adjusts feed rates, manages the repair and installation of electrical systems and hardware at the Water Treatment Plant, tests water samples to ensure the quality of water processed and delivered by the plant, collects samples at customer locations when conditions warrant, and any other duties needed to keep the water treatment plant functioning at peak performance.

Hopefully, this description gives you some insight on how we make potable drinking water here in Ripley, Tennessee.