Lafayette Water Treament Plant

The city of Lafayette gets its water entirely from the Chicot Aquifer which is the largest aquifer in the state and supplies much of southwestern Louisiana with water.  The USGS classifies the Chiciot as a "sole-source aquifer" meaning that there is no viable alternative source for the entities that utilize it for their water supply.  Prior to 1950, ground water flowed from the north to the south within the aquifer.  Since 1950, the flow has changed to the west-southwest because of large pumpage and declining water levels in rice growing areas around Acadia Parish.  In 1963, the water level was lowered enough so that the Atchafalaya River began to recharge the Chicot Auqifer in St. Landry Parish.  Similarly, the Vermilion River has been recharging the aquifer in Lafayette since about the 1950's.  According to Don Broussard, City Water Manager, the water level in Lafayette has declined 35 ft. over the last 40 years (average + 0.78ft/yr).
 

Lafayette has 2 water treatment plants, one on the north-side of town and the other on the south-side of town.  The north-side plant, seen in these photos, has operated for over 50 years and has nine wells that are from
250 ft. to 850 ft. below the surface.  Below is a photo of an old well, this well could pump 1500 gpm.
 

There are  several steps that take place to treat the water after it comes out of the wells to improve water quality beyond the minimum that is required.  First, lime (CaOH) is added to soften the water.  Chlorine is added next to help remove excess iron.  Alum (AlSO₄) is then added as a coagulator that creates a sludge which falls to the bottom of a settling tank, effectively acting like a filter.
 

This is what the mixture looks like after the Chlorine, Lime and Alum are added.

The water skimmed off the top of the settling tank then passes through a 42 inch anthracite coal bed that sits on top of graded gravel for support.  The filter is backwashed every 72 hours for about one minute to loosen material on the coal so that it can be drained off.  The gray pump is the backwash pump and the others send the water to the city's distribution system.
 

This room is where the Chlorine is added.  The chlorine comes in as a liquid and is converted to a gas and then dissolved in water and added to the treatment system.

These tanks below are part of the city's distribution system.  This system has been continually upgraded since it was first established in 1930.  Total usage for Lafayette averaged about 7.2 bgy (billion gallons per year) or
19 mgd (million gallons per day).