PROJECT: Cal Park Tunnel

Cal Park Hill Tunnel Multi Use Parkway– Phase B

Location: Marin County, CA
General Contractor: Ghilotti Construction Inc.
Equipment: Excavator-mounted Lo-Dril

Work Performed:

  • 54 EA 24” diameter fully cased CIDH piles to depths of 54’
  • 2 EA 44” diameter CIDH abutment piles for a bridge over Bellam Boulevard

Completed in December of 2010, the Cal Park Hill Tunnel project made commuting from San Rafael to Larkspur easier than ever for bikers and pedestrians. The piling work presented Hillside Drilling with a unique set of challenges due to the need for fully-cased 24” CIDH piers under an existing bridge deck, combined with hard rock drilling conditions. Hillside crews and management worked tirelessly alongside Ghilotti Construction to get the job done safely and on time.

“Hillside Drilling’s crews and equipment were able to meet the project schedule while dealing with tight access, low overhead restrictions and embedment of piles through soft bay mud and into hard Franciscan Sandstone rock.”
Said Najafi, Project Manager, Ghilotti Construction Inc.



(1) The bridge over Bellam Boulevard helps commuters find an alternative to driving to reach Larkspur and the ferry terminal. HSD drilled 42” abutment piles to support the steel structure.

(2) Hillside Drilling crew members work to set 26” spiral-welded permanent casing with the drill rig. Due to the low bridge deck, sections of casing were pre-drilled then vibrated into the ground with an EMV 400 vibro hammer attached to a Cat 322 excavtor..

(3) As the drilling crew continues to make progress, the ground crew prepares to set cages and pour concrete.

(4) A core barrel is emptied after making a pass in the rock.

(5) HSD general superintendant Dave Lamont and the geotechnical engineer stand over a pile of cores taken from under the overpass.