The Battery Park Trunk Sewer Emergency Tunnel project was necessitated by the collapse of a large diameter 80 year old arch sewer located near downtown Richmond. On a fast-track schedule for the City, the entire 3,300-ft-long, 12-ft diameter tunnel project was designed and constructed within 18 months. Besides the short schedule, route planning and design were further complicated by the presence of a large urban landfill located above the majority of the project area.
Lachel performed site reconnaissance, researched historical geotechnical information, and aided in the evaluation of various route alternatives. Lachel’s preparation of the geotechnical profiles helped identify the limits of municipal solid waste (MSW) located along the alignment and allowed the development of alternatives that minimized its impact. Particular attention was given to the effects and risk associated with tunneling in the MSW, which would be impossible to avoid completely, and to the ground response to tunneling of the primary host material, a stiff Miocene Clay.
Lachel developed separate cost estimates for each of the major tunnel alignment alternatives proposed; and based on the selected alignment was responsible for completing the tunnel design. The effort included design of NATM shafts and all required tunnel initial support and final lining, preparation of contract drawings and specifications for the tunnel and shafts, development of the project Geotechnical Baseline Report, and preparation of the Engineer’s Opinion of Probable Cost.
During construction, Lachel provided construction management services including review of all shaft and tunneling related submittals, and evaluation of contractor Value Engineering proposals.