Eastern Services Area Secondary Connection Project

Project Details

Auger Boring

  • 20-inch water pipeline
  • 350-foot crossing of Interstate 8
  • 48-inch steel casing

Geotechnical Conditions

  • Weak granodiorite rock with boulder-sized corestone material
  • Silty sand and fill


  • Avoid impact to existing utilities
  • Difficult geotechnical conditions

Project Overview

BTE served as the trenchless subconsultant to Michael Baker International for the design of a 350-foot crossing of Interstate 8 in Lakeside, CA.  BTE specified open-shield pipejacking for the installation of 48” steel pipe to serve as casing for the 20” water line.  Alternative excavation head options were allowed including use of a Robbins SBU-M. Ground conditions at the site consisted of weak granodiorite rock with floating, boulder-sized corestones of granitic rock with strengths as much as 10 times that of the surrounding material.  BTE helped to establish contractual baseline ground conditions to be used for bidding purposes and for resolution of any DSC claims.  During construction the contractor proposed to use auger boring methods in lieu of the specified method.  When the conventional auger boring methods ran into difficulties with the corestones, the equipment was augmented with a Robbins SBU-A to complete the work.  The baseline statements regarding anticipated conditions within the granodiorite were successfully used to resolve the contractor’s subsequent DSC claim.