As the excavator scraped the side of the stately colonial brickhouse at 4825 Glenbrook Road N.W., people gathered to watch the long-awaited demolition in Spring Valley.
"Today marks a milestone of an extremely complicated project that continues with a strong collaborative partnership with our regulatory partners and other stakeholders," said Dave Morrow, deputy district engineer for Programs and Project Management for the U.S. Army Corps of Engineers, Baltimore District.
This property is part of the Spring Valley Formerly Used Defense Site (FUDS), which consists of approximately 661 acres in the northwest section of Washington, D.C. During the World War I era, the U.S. government used the site, known as the American University Experiment Station, for research and testing of chemical agents, equipment, and munitions. Today, the site encompasses approximately 1,600 private homes, including several embassies and foreign properties, as well as the American University and Wesley Seminary.
The Army Corps of Engineers has been actively investigating and cleaning up the Spring Valley FUDS for almost 20 years. This work includes the identification and removal of arsenic - contaminated soil, a groundwater investigation, and the search for additional munitions, both in burial pits and isolated items on residential properties.
Crews from Demolition Services Inc. began work on Nov. 29 and by noon on Nov. 30, all that remained was one lone-standing chimney at 4825 Glenbrook Road - which sits on a piece of property believed to be the site of the Sgt. Maurer Burial Pit.
"In the mid-1990s, the Corps of Engineers received a 1918 photo from the Maurer family depicting Sgt. Maurer disposing of chemical-filled carboys," said Brenda Barber, project manager for 4825 Glenbrook Road. "This is the only historical photo we have that shows disposal at the American University Experiment Station."
The team used a technique called photogrammetry, which is the science of making measurements from photographs, to pinpoint the location of the Sgt. Maurer pit by comparing historical aerial photos to current day maps.
"In addition to the historical photos, we started investigating the Korean embassy property next door in 1999 and realized that items of concern also were present on 4825 Glenbrook Road," Barber said.
The 4825 Glenbrook Road property has since been the focus of two thorough investigations (2000-2002 and 2007-2010).
"More than 500 munitions items, 400 pounds of laboratory glassware, and more than 100 tons of contaminated soil were recovered and safely removed during the two past investigations," Morrow said.
During these previous investigations the Corps of Engineers discovered the materials of concern not only on the lot, but adjacent to the foundation of the house and encased into the foundation of a portion of the retaining wall on the site.
"Based on these previous investigations, we knew there would be a greater chance of finding more materials," said Barber.
The Corps of Engineers, along with our partners on the project, the Environmental Protection Agency and the District Department of the Environment, considered various cleanup alternatives for the property.
"Based on input from our partners, several government agencies, the property owner (American University) and the public, we chose to remove the house, cleanup, and restore the property to residential standards, providing for unrestricted future use of the property," Barber said. "Removing the house allows for the best access to clean up any material that is immediately adjacent to the structure, as well as any material that might be under it."
Moving forward, Demolition Services Inc., along with Parsons, the project's prime contractor, will begin debris removal and clean up at the site to prepare for excavation.
"After the holidays, we will begin relocating site utilities and performing some limited low probability excavation work in the backyard of the property, where we do not expect to find American University Experiment Station materials based on historic and investigative field data," Barber said.
Following completion of the initial low probability work, contractors plan to place a large Engineering Control Structure over the site to prepare for high probability excavation, including removal of the basement slab, as well as continued excavation underneath the structure to competent saphrolite or bedrock. Historical and field data indicate the high probability areas of the property have a greater likelihood of containing American University Experiment Station debris and/or glassware items.
"The Engineering Control Structure will fully enclose the high probability excavation areas, and the use of three Chemical Agent Filtration Systems will filter the air leaving the control structure so that any person outside of the tent is safer than those working inside the tent," said Barber.
All of the materials removed during the high probability phase will be safely disposed.
"The basement slab and exterior basement walls remain in place and will be removed during high probability work," Barber said.
Following completion of the high probability phase, the Corps of Engineers plans to finish up with the remaining low probability excavation areas. After completion of the low probability work, the team will restore the site and release it back to American University by spring 2014.
Safety remains the focus for the U.S. Army Corps of Engineers.
"The safety of our site workers and members of the community remains our number one priority and serves as the driving force behind each and every decision made on this Spring Valley Formerly Used Defense Site," Morrow said.
Andrea Takash contributed to this article