The most commonly used materials are bentonite chips and clay. Suppliers are listed under Water Well Equipment and Suppliers in the yellow pages or contact the agencies given below. Clay should be excavated from below the root zone so that it is free of organic matter. Clay must be carefully shoveled into the abandoned well and tamped continually. The use of cement to seal abandoned wells should only be considered by an experienced well driller.
Specialized equipment is required to properly place the cement below the water level.
Although the easiest and most effective way to seal a well is to completely with low- permeability material, the cost may be prohibitive. If a well has a large diameter or is very deep, then the use of a low cost filler material such as sand, carefully placed in certain portions of the well, is acceptable. Sand must be used in combination with either clay os bentonite chips to reduce the potential for vertical movement of groundwater in the abandoned well. Volume of Materials Required Knowing the well depth and diameter and the method of sealing, the amount of each material required can be estimated using the table below. Of sand 50 lb.