DYWIDAG Strand Anchors secure Willow Island Hydro-Electric Project in West Virginia
The Willow Island Hydro-Electric Project is currently under construction in northern West Virginia, USA, near the town of St Marys. The Willow Island reservoir has a total surface of 6.65km² (1,644ac) and is retained by a 343.8m (1,128ft) long dam.
The powerhouse will generate an average annual output of 239GWh with two horizontal 22MW bulb turbines. The water will be diverted from the dam and the Willow Island locks that were built in the 1970’s to the turbines. In addition to a reinforced concrete powerhouse, an intake approach channel and a tailrace channel are being built for the new hydroelectric project.
For the construction of the new hydroelectric powerhouse, an approx. 30.5m (100ft) deep rock excavation had to be built. The excavation support was mainly needed due to a fault line discovered in the rock. Consequently, the design engineer decided to use DYWIDAG Strand Anchors to ensure the stability of the dam during the excavation.
DSI USA supplied twenty-eight 59-0.6" DYWIDAG Strand Anchors. In order to monitor the forces in the anchors during excavation, three DYNA Force® Sensors were installed on each permanent anchor, totaling 84 DYNA Force® Sensors.
For the first few months during anchor installation, sensor readings were manually taken once a day to monitor the forces acting on the anchors as the excavation progressed. Afterwards, the DYNA Force® Sensors were connected to several multiplexers using extension cables, and all multiplexers were connected to the readout unit via a main cable. A modem, a controller and a cell SIM card were installed so the data could be accessed from a remote location. A battery and solar panels were used to power the readout unit.
The data from the DYNA Force® Sensors are being remotely taken every 3 hours, analyzed and reported to the owner. The sensor readings are providing valuable information and added safety during the construction of the powerhouse.
In addition, DSI USA also supplied 42 temporary DYWIDAG Strand Anchors with 3-12 strands in lengths between 15.8m (52ft) and 25m (82ft) to provide temporary soldier pile wall support in the excavation.