Evaluation of Grouting for Hydraulic Barriers in Rock

In January 1964, Engineering Geology made its debut as the bulletin of the Association of Engineering Geologists. The inaugural issue consisted of a collection of five papers on grouting, which were presented at the 6(th) Annual AEG Meeting in San Francisco, California, in October 1963 (Campbell and Daly, 1964; Fabregue, 1964; Grant, 1964a; Karol, 1964; and O'Neil and Lyons, 1964. The authors of those papers shared their experience on various projects employing grouting as a means to create a hydraulic barrier in the subsurface. Nearly a half century later, grouting continues to play a prominent role in the profession. The present authors continue the tradition of sharing experience by discussing methods for evaluating the adequacy and progress of grouting and items to consider in evaluating the performance of grouting for hydraulic barriers in rock. Methods to evaluate the adequacy and progress of a grouting program include analysis of drilling data (water losses and water levels), water pressure testing results (closure trends), grouting records, and piezometer data; drilling, imaging, and testing verification holes; seepage monitoring; excavation; and performance testing. Items to consider in evaluating the performance of grouting include grouting objectives, grout materials and mixes, grouting methods and procedures, hole geometry and spacing, hole sequencing and staging, and field quality control.