This Week - Ongoing Work - 11/18/02 through 11/22/02
- The majority of CVC related construction activity is now occurring within the construction fence and the site is secured by the U.S. Capitol Police.
- Significant tunnel construction activity begins this week along upper Northwest Drive.
East Front Plaza Work (Inside the Construction Fence)
- Construction of the CVC foundation walls continues on the north side of the site. Concrete placement continues and two large construction vehicles fitted with “clamshell” buckets will continue to excavate the foundation wall trenches. Both clamshell excavation vehicles are situated on the north side of the site and one of the vehicles will begin work immediately adjacent to the east face of the Capitol later this week.
- Earth-moving and soil removal activities continue at several locations across the East Plaza.
- Crews continue to place concrete for the guide walls in the northern half of the site.
- Steel beams are being installed in some locations around the Senate Egg to provide earth retention and facilitate excavation activities.
House Side (Outside the Construction Fence)
- No work expected.
- The South Door, the House Steps and the House Carriageway Door remain accessible to pedestrians throughout construction.
Senate Side (Outside the Construction Fence)
- CVC tunnel construction work has begun in a portion of upper Northwest Drive and this work will last approximately 12 months. Senate staffers who are assigned parking spaces within the affected zone have been provided information regarding alternate parking locations and access routes to these locations.
- CVC tunnel construction work also continues along the east side of New Jersey Avenue NW between Constitution Avenue and C Street. The east sidewalk in this location will continue to be closed, but the west sidewalk is accessible. The street will continue to be restricted to one lane and one way traffic traveling southbound.
- The North Door, the Senate Steps and the Senate Carriageway Door remain accessible to pedestrians throughout construction.
Next Week - Anticipated Work - 11/25/02 through 11/29/02
East Front Plaza Work (Inside the Construction Fence)
- Foundation and guide wall excavation and construction will continue in locations across the CVC project site. Some large equipment will be situated close to the east face of the Capitol building on the north side.
House Side (Outside the Construction Fence)
Senate Side (Outside the Construction Fence)
- Work will continue in a portion of upper Northwest Drive and along New Jersey Avenue NW for construction of the CVC service tunnel.
Description of Foundation Wall Construction Process
Construction of the outer foundation walls for the CVC occurs in a series of steps. First, approximately 8 feet of the existing ground is removed along the perimeter (footprint) of the CVC to clear the way for construction of concrete guide walls. Guide walls are two parallel walls that measure 18 inches wide with a height that varies between 4 and 8 feet, depending on the existing elevation. The walls are aligned so that an approximate 3-foot gap is maintained between them. Once the guide walls are in place within a specific zone, a large red “clamshell bucket” is lowered into the gap between the walls and the bucket is used to excavate a narrow trench to an approximate depth of 70 feet. A muddy mixture called “slurry” is poured into the trench as soil is removed. The slurry maintains the stability of the side walls of the trench until a steel rebar cage is emplaced within the trench and concrete is poured. As the concrete fills the trench, the slurry is displaced, removed and reused. Once the concrete within the trench cures, a portion of the outer wall of the CVC is established. As the outer wall of the CVC is completed, excavation will continue inside the wall to a depth of approximately 50 feet.
The slurry wall construction process, especially where it occurs adjacent to the Capitol Building, minimizes any potential disruption to the Capitol Building foundation, since the CVC foundation walls are formed and in place before deep excavation begins.
If you have any questions about the Capitol Visitor Center Project, please contact Tom Fontana, CVC Project Communications Officer for the Architect of the Capitol, at (202) 228-1310, or by e-mail at tfontana@aoc.gov
If you experience any problems with building services inside the Capitol, please contact the Capitol Building Service Center.
