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30 Engineer January–April 2014 T he U.S. Army Corps of Engineers (USACE), Baltimore District, has spent two decades investigating and cleaning up Spring Valley, a community in northwest Washington, D.C. Around the time of World War I, the U.S. government used the American University Experiment Sta- tion site to research and test chemical agents, equipment, and munitions. Today, the site encompasses about 1,600 private properties, including the homes of U.S. government offcials and public fgures, foreign embassies, and facilities for American University. In 2000, USACE discovered that one of the properties contained a burial pit. After two investigations recovered large quantities of munitions, glassware, and soil con- taminated by arsenic and other chemical agents, it was determined that other items of concern could be present in uninvestigated areas, particularly around and beneath one particular structure. Following extensive reviews and a pub- lic comment period, USACE decided to remove the house and clean up the property. People passing by the property during the last year probably noticed the site's enormous transformation. A stately colonial brick house once stood on the half-acre property, now owned by American University. After thorough coordination and input, the house was razed in November 2012, making it the frst house to be removed from a former defense site. Once crews demolished the house, they began preparing the site for high-probability operations. The team uses the phrase high probability to emphasize the likelihood that it will fnd and remove chemical warfare materiel in specifed areas of the property. Site preparation included digging test pits in several areas of the property, relocating utilities, and installing the engineering controls needed to safely remove debris. Removal operations began in September 2013 and will last approximately 1 year, depending on the types and amounts of debris encountered. The goal is to completely remove any remaining World War I era debris and restore the property to residential standards by late 2014. Staffs from across USACE, Department of the Army, U.S. Environmental Protection Agency, District Department of the Environment, and American University have worked on the investigation, said the project manager. She said that the team is prepared for the discovery of potentially dan- gerous debris throughout the project and is using proven engineering control technologies to protect workers and the community throughout the complex environmental cleanup process. The property rises approximately 30 to 40 feet on three plateaus, making it challenging to place equipment for the operations. Each of the key pieces of equipment has been tested and used for years at other defense sites across the country. Where the house once stood, there is now an engineering control structure (ECS), a large tent of polyurethane mate- rial pulled taut over a metal skeleton. The ECS is secured to the ground and kept under negative air pressure by chemical agent fltration systems, which ensure that no air will escape from it. Assurance that the ECS is under negative pressure has been tested and proven by Edge- wood Chemical Biological Center, part of the U.S. Army Research, Development, and Engineering Command. Under the structure, workers in full personal protec- tion equipment remove soil by excavator and sometimes by hand, digging down to bedrock to fnd and remove debris. USACE Removes World War I Era Munitions A dig team trains inside the engineering control structure wearing full personal protective equipment. Careful Cleanup: EN Takash.1.indd 33 3/12/2014 1:37:38 PM