ACT was contracted to for the installation of a 150 foot deep 5 row grout curtain investigation program. The program was undertaken to investigate the feasibility of a grout curtain as a water seepage barrier at a proposed quarry location. The work included drilling holes in rock, washing grout holes, hydraulic conductivity testing of grout holes, production grouting, and diamond core drilling for post grouted verification purposes.
Real time electronic monitoring and recording of actual grout flows and pressures were utilized to analyze and direct the grouting program. Electronic monitoring was accomplished utilizing electronic flow meters and electronic pressure transmitters connected to each grout hole, transmitting the flow and pressure data to an xy-recorder linked with a personal computer.
An extensive grout mix testing program was used to develop grout mix formulations for the project and routine grout mix testing was performed to ensure that mix properties were maintained throughout the project. Highly variable karst zones were prevalent throughout the rock formation and were effectively grouted with a low mobility grout. Grouting materials used included: sulphate resistant portland cement, bentonite, superplasticizer, welan gum, silica fume, and engineered prebagged sanded low mobility grout.
Post grouted hydraulic conductivity values measured in diamond drilled verification holes were used to validate the design requirement of 5 lugeons.