For a new raw water intake structure, Drill Tech installed a shaft and three tunnels at the edge of the South Fork Holston River. From the shaft, a 9′ diameter horseshoe tunnel was driven 1,100′ from the river to the existing water treatment plant on the opposite side of TN State Route 93. Four 48″ diameter shafts were drilled down to intersect the tunnel from the surface of the treatment facility. Extensive cut off grouting and chemical grouting were required throughout tunnel excavation to minimize groundwater inflows of up to 300 gallons per minute. Mechanical piping, electrical pumps, and CIP concrete structures were installed to pump water vertically into the treatment facility for processing.

Roughly 320′ of the tunnel was constructed in Limestone using jacklegs and drill/blast methods. The remaining 780′ was constructed in claystone and excavated using an AM-50 roadheader. Hollow bar spiling was implemented as extra ground support in areas of minimal cover. Drill Tech was responsible for all ground vibration monitoring during blasting activities, with blasting that occurred within 7′ of existing structures.