Specialty Grouting Contractor responsible for the design and installation of an emergency grout curtain in soil and rock for a hydroelectric dam, which had experienced sinkhole formations and piping failure of the earthen abutment. The work included rotary drilling of grout holes through overburden and core drilling holes in rock, installation of overburden casing, hydraulic conductivity testing of grout holes, production grouting, diamond core drilling for verification, and contact grouting of the overburden/rock interface.

Grouting was accomplished utilizing sleeve-pipes (tube-a-manchettes) fitted with geotextile barrier bags. The geotextile barrier bags were inflated with low mobility grout to create 2m zones for pressure grouting. In addition, a series of injection pipes were installed along the alignment where piping and sinkholes had formed. The injection pipes were injected with low mobility compaction grouts to stabilize the soils where piping had occurred. Both the soil and rock were injected through the sleeve-pipes during the remedial repairs and the final cut-off wall was reduced to a lugeon value of 6 or less which met the design requirement of 6 lugeons.

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.

Due to the critical nature of project, the work was completed on a 24 hour per day basis, 7 days a week. The work was completed significantly ahead of schedule and within budget.

The project was located in the Northern part of Ontario in Canada and extreme winter conditions were encountered. The project was subjected to temperatures of -40 degrees Fahrenheit and heavy snowfalls. No production interruptions or delays occurred as a result of the weather.