A Novel Continuous Conveyor System and Its Role in Record-Setting Rates at the Indianapolis Deep Rock Tunnel Connector

"The Indianapolis Deep Rock Tunnel Connector (DRTC)—first in a vast network of storm water storage tunnels below Indiana, USA—was a wildly successful endeavor. Crews for the Shea/Kiewit JV drove a 6.2 m Robbins Main Beam TBM to world record rates. The machine achieved 124.9 m/day, 515.1 m/week, and 1,754 m/month in limestone and dolomite rock. The advance rates can be attributed to many factors including ground conditions and knowledgeable crew, but continuous conveyors are also of key importance. The novel conveyor system, manufactured by The Robbins Company, enabled continuous tunneling in a difficult layout that included two 90-degree curves and two S-curves. Spanning 11,777 m in its longest iteration, the system included nine booster drives plus a main drive. A vertical belt moved muck up the 76 m deep shaft to a radial stacker for temporary storage. The system, one of the most complex in North America and the first to operate in 90-degree curves, made swift tunneling possible. This paper will examine the world-class tunneling done at the Indianapolis DRTC and the role of continuous conveyance in reaching high advance rates. The logistics of the system will also be examined as it could apply to future tunneling projects with similarly complex layouts. INTRODUCTION The Indianapolis Deep Rock Tunnel Connector (DRTC) is the first phase of a nearly 28-mile long network of deep rock tunnels being built 76 m beneath the City of Indianapolis, Indiana by Citizens Energy Group. The Deep Rock Tunnel Connector (DRTC) Project is a 12.2 km, 5.5 m diameter tunnel constructed by S-K JV, a joint venture between J.F. Shea Construction and Kiewit Infrastructure Co. The tunnel is a $179 million project and is the first segment and southernmost portion of a deep, large diameter conveyance and storage tunnel system to provide overflow relief during wet weather events. The project is estimated to be completed in 2017 and will initially deliver 204,000 cubic meters of the planned 1 million cubic meters of CSO storage for treatment, as well as provide future connections to other tunnels in the overall system (see Figure 1)."