New Windsor, MD
GTA provided geotechnical consultation services to facilitate the design and construction of a five-mile conveyor and associated site improvements between the Union Bridge and New Windsor plants. GTA also provided recommendations for the design and construction of the new rock crusher and 50-foot-tall retaining wall located at the New Windsor site. These services included 46 new subsurface explorations, review of 84 previous subsurface explorations, a new geophysical survey in the area of the New Windsor pit and rock crusher, as well as a review of a previous geophysical survey for the conveyor. The geotechnical explorations included a combination of Standard Penetration Testing (SPT), rock coring, and air track probes to evaluate the soil and rock, and to determine the approximate elevation of the rock surface. The evaluation of the subsurface conditions included laboratory testing of the soil and rock samples recovered from the explorations. Many of the geotechnical explorations included rock coring and recovery of soil and rock samples for laboratory testing. The geophysical surveys included seismic and electric resistivity profiles. GTA compiled several years of new and previous subsurface data to provide design and construction recommendations for the overland and tunneled conveyor sections, as well as the foundations for the rock crusher, retaining walls, transfer towers, and conveyor bents. The limestone associated with the regional geology is prone to karst formations. Possible karst conditions were encountered along the conveyor alignment and below the rock crusher foundations. GTA provided recommendations to mitigate the karst conditions and permit the construction of the proposed structures.