The U.S. Army Corps of Engineers has completed construction on the first of two extensions to its emergency containment structure at 4825 Glenbrook Road, Dan Noble, project manager of the Army Corps' military munitions response program, said during a Spring Valley community meeting Tuesday.
The Corps lengthened the ECS by approximately 17 feet to the east toward AU to further investigate the area, also known as "Pit 3," for remnants of World War I-era munitions or laboratory gear, Noble said.
Due to the structure's modification, the Corps had to amend its Chemical Safety Submission - a document subjecting the structure's design for safety approval. On Monday, the Corps submitted the CSS to the U.S. Army Technical Center for Explosives Safety, which oversees the Corps' Spring Valley project, according to Noble.
"We don't think it should be much of a problem, because we essentially built the structure ... to specifications," he said. "We just made it 17 feet longer."
The Corps' Army managers will then pass the CSS onto the Defense Department's Explosives Safety Board. The board has the final say on the structure's approval, according to Noble. Work at Pit 3 will restart April 28.
The Corps completed excavation underneath the ECS' previous location March 10. Engineers determined they needed to create three structural extensions after geophysical testing - combing the area with a metal detector - revealed the presence of "anomalies," or metal objects, The Eagle previously reported.
Engineers later decided to build only two of the three proposed extensions.
They decided not to build the third addition, which would have extended north along the front side of the house. They cleared the area of the "metallic signal of interest" after workers removed 2 feet of soil that had triggered their metal detectors. Noble said the soil, located outside the structure, probably contained rocks with natural traces of metal or rust.
The Corps still plans to excavate a test pit where the north extension was supposed to go to ensure it adequately inspects the area, according to Noble.
"Test-pitting" consists of digging small holes to search for evidence of chemical weapons or munitions.
The Corps must complete an investigation of the area along the east side of the house before it begins construction of the second extension. The Corps expect to finish work on the second extension by the end of July, according to Noble. The Corps expect to complete the investigations by early summer, depending on the DDESB approval process and what workers discover in each area, according to documents provided at the meeting.
