Location
Nebo, NC
P&J Role
Prime Contractor
Completion Date
February 2011
Nebo, NC
Prime Contractor
February 2011
The Duke Energy Carolinas Bridgewater Hydroelectric Project near Nebo, North Carolina, consists of the Paddy Creek Dam, Catawba Dam, and Linville Dam, which together form Lake James. Based upon a nationwide effort initiated by the Federal Energy Regulatory Commission (FERC) to improve the performance of existing dams during large earthquake events, Duke Energy Carolinas was required to implement embankment seismic stability improvements (ESSI) to comply with FERC requirements. The engineering designs approved by Duke Energy Carolinas for the ESSI projects included the construction of large earth and/or concrete structures along the downstream slopes of the dams to mitigate potential damage during a future earthquake.
P&J was awarded the contract for construction of the Catawba Dam ESSI Phase I & Phase II Projects. The Phase I Project involved preparation for the actual modification of the dam and spillway structure. Specific activities performed by P&J included grading and construction of a temporary entrance from State Route 126; clearing, grubbing, and stripping of 10 acres around the project site; installation of erosion and sediment control measures; construction of two sediment basin structures; construction of support facility pads; excavation; placement of 8,400 tons of aggregate base and FlexTerra; and temporary seeding of three acres.
The Phase II Project was 150 acres in size and involved construction of a new earthen embankment downstream from the original dam. Specific activities performed by P&J included clearing and grubbing of 116 acres around the project site; construction of haul roads and retention ponds; installation of erosion and sediment control measures; site development excavation; foundation dewatering including design, installation, operation/maintenance, modifications, and systems removal; foundation excavation and spillway channel material; installation of fine and coarse blanket filter drain material; placement of foundation backfill and berm embankment; installation of an inclined chimney filter drain and seepage collection channel; and final site restoration, including seeding and mulching of 150 acres, degrading of haul roads which required the relocation of material, and seedling reforestation of 135 acres. Additional activities performed by P&J included import of aggregate for Roller Compacted Concrete (RCC) and construction of RCC buttress and wing walls, demolition of spillway face and resurfacing of the demolished spillway face with concrete, demolition of the right bulkhead and wing wall, and conversion of 68’ of the right bulkhead to a new ogee crest spillway.
