Pacific Gas and Electric Co. contracted with Kiewit
Pacific to complete a design and undertake submerged repairs
to the 10' diameter 700 foot deep Middlefork hydropower surge
shaft. This shaft could not be dewatered due to its structural
condition.
Kiewit elected to install an 8' diameter steel liner within the open shaft, however, this plan required the
installation of rock bolts drilled from within the liner out to a
distance of 16 feet through rock at a water depth exceeding 500
feet.
J. F. White designed a hydraulic drill system that was
monitored and operated with an Atmospheric Diving System (ADS) support. We have
successfully completed a proof-of-concept utilizing this system in a shallow test facility.
