Estimating Grout Quantities for Residential Repairs in Central Florida Karst

By law, certain property damage attributed to sinkhole activity is covered by homeowners' property insurance in Florida. Engineers must devise and implement proper remedial techniques that include the stabilization of the house against future settlement. The remedial efforts most commonly used include underpinning, pressure grouting, or a combination of these two methods. The engineer usually has to provide a cost estimate for these repairs, along with detailed specifications for the contractor. Madrid Engineering Group, Inc. reviewed over 20 houses that were remediated by void filling and densification of raveled soils using low mobility grout, and determined that there was a wide variability in the estimated grout versus the actual grout. In order to obtain better estimates, the grout data was examined and, after normalizing from the base of the grout pin instead of the ground surface, indicated that three distinct injection regimes were encountered. The lower regime is located within the weathered limestone, and grout takes were generally high. A transition zone with moderate grout takes was noted. The remainder of the hole was generally in soft to firm clays or loose sands, and grout takes were much less. The data were used to provide a more accurate estimate of grout takes for future remediation cost estimates.