DC Clean Rivers Project: Geotechnical Instrumentation Programs for Protecting Critical Infrastructures in the Nation's Capital

摘要

The District of Columbia Water and Sewer Authority (DC Water) Long Term Control Plan (LTCP) (also known as the DC Clean Rivers (DCCR) project) consists of about 14 miles (23 km) of large-diameter tunnels and deep shafts constructed in soils. A total of 15 shafts with diameters up to 149 feet (45 m) and depths up to 193 feet (59 m); three large-diameter tunnels have been constructed in three contract divisions (Divisions A, H, and P) and procurement of a fourth tunnel project (Division J) is underway. The projects of the LTCP are located in the crowded urban environments and extensive geotechnical instrumentation programs were installed to monitor performance of shaft and tunnel construction for the protection of the critical infrastructure, including DC Metro, bridges, water lines, sewers, etc. Experience gained from each project allowed the protection of structures and geotechnical instrumentation requirements to be better adapted for the follow-on projects. This paper discusses how the structure protection criteria were set and tied to the instrumentation monitoring requirements in the RFP documents of the completed divisions and the implementation of the instrumentation programs during design and construction phases. Lessons learned are also included.