We constructed temporary access over the pipeway for mass excavation and construction of a 35-foot tie-back wall and secondary wall. Because of the topography and site access, we excavated and sloped the entire slope, constructed the wall to full height, drilled tiebacks then installed and tensioned through the new wall in concert with the wall backfill. We removed the old pipeway for access and constructed a new pipeway above and around the substation — completing the piping tie-ins without disrupting refinery operations. 

Multiple power pole foundations of differing designs for the main feeder were constructed for the 115Kv feeder lines into the substation, some up to 10 feet in diameter and more than 40 feet deep and others being large pile-supported concrete foundations with 15 to 20 piles each. We constructed all underground duct banks as well as the elevated substation foundation and associated structural steel. New distribution pole foundations were constructed, again with some being large deep drilled piers and other being pile-supported hollow concrete poles.

While the original design showed removing hillside and importing new structural fill material from local quarries for the foundation, we processed the existing removed material for uses as the structural fill.

Faced with difficult excavations that required abnormal shoring installation and complex layout, we noticed an unexpected large boulder that presented a hazard to perform the necessary excavation began. We helped redesign the structural upgrades and eliminate the hazard of the boulder, keeping the field crews safe during the seismic retrofit.