Techno’s Project Executive, Prakash Donde, P.E. served as Project Manager as a part of the team serving Washington Metropolitan Area Transit Authroity’s Washington Metro, Section E-4b Tunnel which utilized HDD, and ran under New Hampshire from the proposed Georgia Avenue Station to the completed Fort Totten Station, passing beneath commercial zones and residential communities. The services included design and construction management of the single track twin tunnels, two vent shafts, one fan shaft, one emergency access shaft and one electrical substation. The total length of the tunnels was 6,800 lf including 2,400 LF of NATM tunnels situated below Rock Creek Cemetery. HDD Technique was utilized to improve ground above each tunnel crown and to place chemical grout through the HDD Bore Holes. Ten (10) Holes with a total length of 7,000 were drilled with high level of precision.
Construction was accomplished using horizontal directional drilling (HDD), shield bored as well as cut-and-cover construction in soft ground. Concrete segmental linings were utilized to provide initial support for ground. Work shafts on this project were carefully selected to ensure minimal inconvenience to the public.
During the construction phase, The scope of services included construction oversight and inspection; members of our team provided construction services for the construction phase of the project, design of enlarged tunnel sections at the contractor’s request; review of shop drawings; preparation of Dispute Review Board presentations; review and preparation of response to contractor’s claims; and value engineering services.
During the design and planning phase, the team provided the design using conventional tunneling methods and ground improvement using HDD for the tunnels, and shafts. The team prepared tunneling reports which included ground settlement studies and recommended solutions; type of tunneling equipment necessary; and the type of ground modification measures required to perform tunneling under the cemetery. Engineering services for the project included contract drawings for tunnels and shaft instrumentation, chemical grouting, compaction grouting, underpinning requirements, structural design, and preparation of contract specifications.
Washington Metropolitan Area Transit Authority
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