South River Pump Station Power Supply – Lower Northwest Interceptor

Project Details


  • 24″ steel casing for four 6″ and one 4″ PVC conduit for electrical supply and SCADA
  • 1,475′ crossing of Sacramento River levees

Geotechnical Conditions

  • Loose to dense silty sand
  • High groundwater


  • Levee crossings – flood control issues
  • Limited work area on one side
  • Moved rig to exit side for pullback
  • Close proximity to established residences

Project Overview

Bennett Trenchless Engineers provided trenchless assistance for the design of a power supply crossing of the Sacramento River. The crossing provided electrical power from an existing substation in the Pocket neighborhood of Sacramento to the new South River Pump Station on the Lower Northwest Interceptor Project, west of the Sacramento River. The crossing consisted of a 1,475-foot long, 24-inch diameter steel casing pipe containing four 6-inch PVC conduits for the electrical conductors and one 4-inch PVC conduit containing fiber optics for a SCADA system.  The casing passed beneath flood control levees on both sides of the river.

The design of the crossing required special sequencing to minimize disruption to the residents in the Pocket neighborhood. The contractor was required to both drill the bore and fabricate the pipe on the west side of the river. Only after the bore was ready was the contractor allowed to mobilize the drill rig to the neighborhood on the east side of the river to pull the casing and conduits into place. The contractor was also required to contact grout the ends of the bore to prevent seepage of floodwaters along the bore annulus beneath the levees.

Bennett Trenchless Engineers provided preliminary design services, developed a risk matrix to select alignment, conducted pullback and pipe stress calculations, provided drawing edits, drafted technical specifications, prepared a Hydrofracture and Surface Spill Contingency Plan, provided planning level cost estimate, reviewed contractor’s submittals, and provided technical permitting support for California State Lands Commission lease.