Wind Farm Construction Provides New Market For HDPE Installations

March 2014, Vol. 69 No. 3

Some of the largest wind farms in the United States are using large diameter, solid wall high-density polyethylene (HDPE) conduit to protect electrical cables and the environment.

While the conduit provides long-life, it is also helping projects to be cost-effective.

"HDPE conduit has the right cost-to-benefit ratio that includes the pipe stiffness necessary to withstand the weight of deep burial while being able to be flexible and strong enough to allow for horizontal directional drilling (HDD)," stated Tony Radoszewski, executive director of the Plastics Pipe Institute Inc., (PPI), the major trade association representing all segments of the plastic pipe industry.

"It is ideal especially for projects where there is a need to reduce the amount of digging such as in a wetland or by going under roads to keep them intact. HDPE conduit can be 'snaked' underneath. Plus, the HDPE conduit is flexible enough to resist seismic shifts. The polyethylene itself is chemically resistant to high acidity or alkalinity from the soil. The length of HDPE conduit in either long 'stick' sections or hundred-foot coils can reduce the number of mechanical joints necessary for the installation, which in turn, reduces the overall project costs.

"What is especially important for electrical cable use," he continued, "is that HDPE conduit does not require any cathodic protection that would be needed to prevent corrosion of a pipe with a metal surface.

One of the newest wind power operations, the Beebe Wind Farm in Breckenridge, MI, has 34 turbines operational with another 16 to come on-stream in 2014. The crew from M. J. Electric LLC (Iron Mountain, MI) found the use of HDPE conduit also improved installation time and enabled the crew to use either cut-and-cover trenching or HDD. The 34.5kV lines are housed in the eight-inch diameter HDPE conduit and are buried as deep as 30-feet with some runs being 1,000 to 2,000 feet long. The land used for the Beebe Wind Farm is an agricultural farm.

"There are usually four or five turbines on a circuit which are strung together with an underground collection cable out in the farmer's field or the grasslands, depending on what part of the country we're in," explained Rick Moore, director of purchasing, M. J. Electric. "Ultimately, each circuit collecting the energy generated by the wind turbine ends up at a substation."