“ROADWAY” FOR 8.8 MILLION POUND DRAGLINE
An Engineering Excellence Award-Winning Project

S&ME overcame significant engineering challenges to assist PCS Phosphate to cost-effectively move an 8.8-million-pound dragline (nearly as heavy as the Cape Hatteras lighthouse) across two miles of its phosphate mining site near Aurora, North Carolina. Our engineers studied potential outcomes from a variety of possible solutions and recognized that the off-road roadway design must account for significant soil changes caused by the enormous weight as the 25-story-tall dragline was moved to a new mining tract.

The "roadway" had to cross an anything but typical terrain, and to be truly cost effective, the most direct route possible had to be used. We also had to design geotechnical solutions that would allow our client to use its own personnel to construct the roadway. Excessive soil settlement beneath the machinery, poor soil support or the collapse of embankment slopes could leave a $36 million dragline literally stuck in its own tracks. The route had to cross a wide variety of natural coastal plain deposits, including very loose to dense sand and both soft and stiff clays. Added to that were areas of mine spoils with sand-tailings fill and bucket-wheel spoil, each having unique strength characteristics. 

S&ME performed soil test borings and lab testing, aware that analyses and soil engineering properties would change as new fill was added to the route. What's more, the sheer weight of the massive equipment would continually change conditions as it was moved along the route.

Our design, which included a roadway five times wider than a more typical approach, allowed PCS to realize all its requirements for the project. The move was made in only a few months, a fraction of the time anticipated had the design used "soil improvement" methods typically offered by specialty contractors. The two-mile move was made, without incident, across a "roadway" constructed as hoped for by client personnel.