Prehistoric Landscapes of the Nation's Capital
Excavating the Whitehurst Freeway Sites – Challenges
Archeological testing in the Whitehurst Freeway Corridor revealed that intact archeological resources were buried beneath anywhere from 3 to 17 feet of historic fill. Filling along the banks of Rock Creek began as early as the first quarter of the nineteenth century when the excavation of the Chesapeake and Ohio Canal resulted in the availability of fill that was used to reclaim swampy areas near the confluence of Rock Creek and the Potomac River. For example, the nearby Watergate Hotel is located on ground that would have been mudflats in the eighteenth century. The filling continued throughout the nineteenth and into the twentieth century.
The area closest to K Street near the Peter House site was capped with the least fill, measuring less than 3 feet in depth. As the ground sloped down toward Rock Creek, the depth of fill increased, with about 8 feet of historic fill above Feature 283 at Ramp 3 and 14 feet of fill over Feature 502 at Whitehurst West. In order to remove the fill to reach undisturbed archeological features and layers, a backhoe was used. Upon encountering intact archeological deposits, hand excavation began.
Archeological excavations complied with OSHA safety standards, either utilizing a 1.5:1 slope or employing benching or shoring. Whitehurst West, located closest to Rock Creek, was excavated in the winter of 1996-1997. Water problems were encountered because of the proximity to Rock Creek and the wetness of the season. Well points were drilled to allow for excavation by lowering the water table. Because of the depth of the excavation (14 feet below ground surface) and limitations in expanding the trench, due to the proximity to the Rock Creek Parkway and a jogging path, shoring was constructed to assure safety. A shelter was built over the excavations to protect the archeologists from the cold and allow research to continue in sub-freezing temperatures.