Lime Softening Plan

In compliance with new regulations, new covers have been installed on the Lime Plant Water Tanks.

The Lime Softening Plant was built in 1961 and has a production capacity of 3.0 MGD (million gallons per day). Operation consists of the following facilities:

AERATION – water from wellfields 1, 2, and 3 is processed through a 5 MGD aerator installed above a 100,000 gallon raw water storage tank. The aeration process removes the hydrogen sulfide and carbon dioxide gases naturally found in ground water, adds oxygen to the water, oxidizes iron and manganese and improves the taste.

SOFTENING – after aeration the water is pumped from the raw water storage tank into the softening and clarification section. The raw water enters a large circular tank where it is mixed with a lime solution. The solution reacts with the calcium and magnesium compounds in the raw water to form insoluble carbonates (sand-like material), which settle to the bottom of the tank where they are mechanically removed. The lime sludge, a by-product of this operation, is pumped to drying lagoons and stored for later disposal. The material is normally used by sod farmers as a fertilizer.

Raw water entering the softening section contains approximately 300 mg/l (milligrams per liter) or 17.5 grains hardness per gallon. Product leaving the plant averages 78 mg/l or 4.5 grains hardness per gallon. After softening, clear water at the surface of the tank is collected and conveyed to the filters.

FILTRATION – the softened water enters the top of the filter tank and flows down through a bed of anthracite coal. Passage through the coal provides clarification. From the bottom of the filter, water is collected and pumped to the clearwell, mixed with water which has been treated at the reverse osmosis plant and pumped to storage tanks.

DISINFECTION – State and Federal laws require that water be disinfected to kill pathogenic bacteria that may be present. Chloramines, a chlorine/ammonia solution, are injected during the treatment process to accomplish disinfection. EWD continues to study new and proposed water quality standard requirements, developing treatment modifications as needed.