The Army Corps of Engineers (USACE) - Baltimore District and the Architect of the Capitol (AOC) replaced an existing retaining wall along an existing earthen berm with a new structural concrete wall. To perform this work, utilities needed to be moved and light poles and a bus stop shelter needed adjusting. SCE provided two geotechnical investigations and reports in the area of the proposed wall and berm. The first investigation was to determine the subsurface soils bearing, classification and stability to design the proposed berm. SCE did all necessary requirements to obtain the District of Columbia Regulatory Agency (DCRA) and Department of Energy & Environment (DOEE) drilling exploration permit and obtained AOC access badges for our employees and our subconsultants employees. Subconsultants hired by SCE included drilling and private utility locating companies. SCE had our Geologist in Training and Professional Engineer onsite during subsurface exploration to make critical decisions while exploration was performed. Our in-house nationally certified laboratory performed all soil classification, and natural moisture tests required for the project.
The second investigation was required to determine a bridging system of the proposed berm to span over an existing tunnel. The designers were concerned the extra weight of the berm could cause a failure of the tunnel and required more geotechnical testing to determine the proper design to span the tunnel. Again, SCE obtained permits from DCRA and DDOE. Finding the exact location of the outside of the tunnel was critical so no damage would be caused and exact soils in the area was observed. SCE worked hand in hand with the AOC, Four Tribes, and the private utility company to find the exact locations for the subsurface exploration. SCE coordinated with the utility marking company, so they were present during field work to confirm the exact location of the existing tunnel and safe areas to bore before any borings began.
Since the location of the work was directly across the street from the US Senate Office Building, field work for both explorations were coordinated and completed on weekends to not disrupt US Senators and the Capitol Police daily work schedules.
SCE provided two detailed geotechnical reports, along with working with the Civil Engineer and the Structural Engineer with the designs of the berm and the bridging structure. Because of our communication and work ethics on the geotechnical aspect of the project, SCE was awarded the testing and inspections during the construction of the berm and bridging structure. The project construction is proposed to start summer 2022.