A simulation model solved the problem of scheduling drilling rigs at Clyde Dam

The Clyde Dam in New Zealand is located in an area more unstable than was thought when it was designed. Therefore, Electricorp has taken additional precautions to ensure the stability of the hillsides surrounding it, constructing an underground grout curtain of 1,362 meters along the Clutha River. A grout curtain is constructed by drilling holes in the rock and injecting concrete into them. With a budget of millions of dollars for hiring drilling rigs, the construction company wanted to minimize the idling time of the drilling rigs and finish the project quickly. The authors developed a simulation model that enabled it to find an efficient drilling schedule, saving about NZ$580,000 on hiring costs for drilling rigs (seven percent of drilling hours hired) and 10 weeks (about 26 percent of project completion time).