Fixing the Leaks of the Rondout-West Branch Tunnel: Repairs and a Bypass Tunnel

摘要

The Rondout-West Branch Tunnel (RWBT) carries roughly half of New York City’s drinkingrnwater from upstate watersheds to the Westchester County reservoirs. The tunnel is leaking up to 35 millionrngallons per day in two different locations. This paper details the design of the Bypass Tunnel that will eliminaternthe Roseton leak, and the design of the in-tunnel repairs for the Wawarsing leak. Major challenges for thernconstruction of the new Bypass Tunnel include tunneling through fractured and faulted ground while managingrnup to 800 feet of head (24 bar) of external water pressure, constructing a tunnel lining to withstand 1,200 feetrn(36 bar) of internal pressure, and connecting the Bypass Tunnel to the RWBT in a minimum amount of time.rnOther challenges include the design of an inspection program for the entire 45-mile tunnel length and planningrnan in-tunnel grouting program to repair the Wawarsing leak.