Friday, March 25, 2011

Irrigation Water Treatment with FGD Gypsum

Here at The Preserve Golf Club we have a 'sodic' irrigation water source with a Sodium Absorption Ratio (SAR) value of 30.  The term sodic is used to describe water sources that have a SAR of over 15.  The SAR is simply a value that is used to evaluate the potential for Sodium (Na) to build up in the soil resulting in the break down of soil structure and reducing water infiltration.

Calcium (Ca) is the counter ion to Sodium and the key to proper soil structure.  Na destroys soil structure while Ca builds soil structure.  Ca counteracts Na from the soil if it is provided in a high enough quantity and in an available form (CaSO4, CaNO3, CaCl2).  The available form of Ca that is the most economical to our location is a material referred to as FGD gypsum (CaSO4).  FGD gypsum is a by product from the newer coal burning plants in Georgia.  This synthetic form of gypsum is produced by new scrubbing systems installed in coal burning power plants to reduce the amount of Sulfur released in to the atmosphere.  The power plants scrubbing system produces a very affordable and pure source of gypsum that is used for the treatment of our water.

The process we use for our lake treatment starts with a monthly water testing program.  This program tracks the changes in our water source and provides data to ensure the water is treated only when needed.  When test results show an SAR value above 5 additional gypsum is added to our irrigation lake.  This material is delivered in 25 ton quantities.  The gypsum is distributed into the lake feed  junction box while our 800 gallons per minute well is running.  This produces a tremendous amount of mixing forces that effectively places the gypsum into solution as it feeds into our lake.

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