U.S. Capitol Utility Tunnel

Washington, DC

While time is always critical on a job, it is more critical on some jobs than others. For a utility tunnel that goes under Constitution Avenue and connects the Senate offices in the Hart Building to the Capitol Building, leaving areas exposed for any extended period of time presented serious security concerns. Moisture from conditions on the road surface and from steam lines connected to the tunnel roof, however, had caused extensive deterioration necessitating replacement of the tunnel roof.

Traditional methods and products were not an option. Instead of using jackhammers to chip away at the deteriorated tunnel roof, Eastern Waterproofing & Restoration devised a system to remove 5' x 5', 14'' to 16'' thick slabs to expedite the job. Traditional waterproofing products were also replaced with TREMproof® 250GC Fluid-Applied Elastomeric Waterproofing Membrane from Tremco Commercial Sealants & Waterproofing to drastically reduce the time the tunnel needed to be open. Since TREMproof 250GC can be applied to “green” concrete, there is no need for an extended delay before application of the waterproofing. Instead of having to shut the street down and leave the tunnel open for up to 28 days before waterproofing could be applied, TREMproof 250GC was put down after only three days of wet cure, in two lifts up to 220 mils followed by a protection mat, and had cured in four hours. With 20-man crews working six days a week, the entire 8,700- square-foot concrete roof had been removed, replaced and waterproofed. In addition, waterproofing had been applied down each side (another 5,400 square feet) – all within four months.