Rex Cochran
Rex has 45 years of experience in the construction industry and nearly 20 have been with Drill Tech, where he operates as a General Superintendent. Mr. Cochran ensures project success in a variety of scopes including earth retention and foundations, most often including CIDH piles and tiebacks. He also possesses specialized knowledge in underground construction and mining work, with certifications including MSHA Surface & Underground, Underground Rescue, Breathing Apparatus, and Certified Gas Testing.
Rex's Featured Projects
CADOT Red Top West Dewatering Shaft | Vallejo, CA
Superintendent
This project consisted of excavating a 20' inside diameter shaft, 154' deep, into the toe of a massive landslide underneath I-80 between Vallejo and Fairfield, CA. Ground conditions consisted of about 55' of sandy clay, 70' of weak rock and very hard rock for the bottom 30'. Extensive probe drilling, dewatering, and grouting were required to control the running ground. From inside the shaft, 131,000 LF of horizontal drains were drilled into the landslide to drain the groundwater into the shaft where it is to be pumped up and discharged away from the slide. The shaft was classified as “Gassy” by Cal Osha due to the presence of methane and was excavated with a permissible electric excavator, manufactured by Drill Tech and equipped with a bucket, a breaker, and a drill attachment. The shaft was lined with lattice girders, rock bolts and shotcrete.
Cal Park Hill Tunnel Rehabilitation and Appurtenances | San Rafael, CA
Superintendent
This Drill Tech contract rehabilitated a 1100’ long, 31’ diameter horseshoe-shaped railroad tunnel. Operations consisted mostly of the demolition and replacement of broken tunnel supports in highly fractured rock conditions as well as wet, mixed face conditions with short initial standup time. This project also required 160’ of re-mining through a completely collapsed section of tunnel, “cut and cover” operations, and temporary support of existing sink holes that reach to the surface. The existing redwood sets that had been rotting were replaced with W8x31 steel sets and the tunnel was then lined with more than 5000 CY of steel fiber reinforced shotcrete to complete the ground support. The project also included a pedestrian pathway that has all the elements of building construction (i.e. CMU wall, steel erection, architectural, electrical and mechanical works).
