Sinkhole Solutions

After determining the presence of a sinkhole, the soil type, density and the likely cause of the settling, the most effective method found to counteract the steady progress of cover subsidence sinkholes is stabilization of the soil itself.

We drill injection boreholes down into the problem area and insert a 3-inch steal casing. Boreholes are typically about ten feet apart, though that can vary according to the depth to rock, accessibility at the surface, soil conditions and so on. Our goal is to drill to the top of competent limestone. That can be as little as ten feet or well in excess of 100 feet. We then attach a 2 ½-inch diameter hose to the casing and inject grout into the unstable soil zones below. The grout itself is a mixture of cement, sand, flyash and water - not unlike the mortar used in bricklaying. Because the grout is pumped under pressure, any voids that exist in the soil or surface of the limestone are filled. At the same time, any soft or weakened soil is also displaced, thereby minimizing the risk of future erosion.

The primary objective is to construct a layer of grout at the top of the limestone layer to prevent the downward movement of sandy soil into large cavities.

Earth Tech's field personnel, using surveying instruments, monitor the miniscule but steady upward progress of the home. The process is repeated in all suspect areas and, when complete, the result is a soil that is dramatically denser and a foundation that is once again stable.