Scope of Project:
Brayman Construction was contracted to perform the Probable Maximum Flood (PMF) Upgrades to the Rhodhiss Hydrostation in Hickory, North Carolina. These upgrades included the construction of three separate concrete walls, a sheet pile wall, a canoe portage and the installation of fifty-five high capacity rock anchors ranging from 12 to 58 strands. The concrete wall work involves constructing a total of 250 lineal feet of 8-ft high by 1’-8” thick extensions at the north and south bulkhead. The south wing wall must also be elongated and raised by approximately 6 ft. A 325-ft long steel sheet pile wall will provide the increased height to the earthen section of the dam. As an active community partner, Duke is also installing a canoe portage along the south bulkhead that consists of a concrete and stone walkway. To protect against uplift at the powerhouse, Brayman will have to core drill thirteen 3” diameter holes within the gallery. The main portion of the work consisted of the drilling, installation, and testing of the fifty-five epoxy coated rock anchors. Spread across the length of the dam, the high capacity rock anchors were installed at both the north and south bulkheads as well as along the face of the spillway. Access along the face of the spillway was provided by constructing a steel frame work platform. Each rock anchor required recessing into the face of the dam to provide adequate concrete coverage to all the anchor hardware. The recesses were excavated using a rotary percussive cutting tool to depths up to 7 ft. Depending on the number of strands required at each anchor location, a 9” or 12” diameter hole was drilled, water tested for tightness and consolidation grouted and re-drilled as required by the specifications. Alignment checks were performed on each hole at three different depths. The epoxy coated strand anchors were then installed using a hydraulic tendon uncoiler and subsequently grouted and proof or performance tested prior to acceptance. After secondary grouting each rock anchor, the recesses were backfilled with 4000 psi concrete. |
