The recently completed Lower Northwest Interceptor Program (LNWI) in Sacramento, California comprises, ten pairs of microtunnels totaling 14,417 ft, three horizontal directionally drilled bores totaling 3,154 ft, and two large diameter tunnels under the Sacramento River totaling 3,953 ft. This paper describes the problems encountered with each trenchless crossing, as well as lessons learned with respect to shaft construction, ground control at shafts during tunnel break-in and break-out, frac-out and heave, settlement, obstructions, coordination with permitting agencies, and application of geotechnical baseline reports.
展开▼
