Desalination Plant Vault Demolition

Owner: Kiewit Shea Desalination Plant

Ballard Marine Construction conducted commercial diving operations to drill, diamond wire saw cut and remove sections of concrete in the channel structures of the desalination plant. Once excavated and shored, our team drilled 3” holes, in the existing concrete channel in order to cut out a square hole via diamond wire saw. Two smaller contiguous holes were drilled on either side of the 3” in order to thread a catch wire and retrieve cores to prevent them from falling into the channel. Divers then threaded the saw wire from one 3” hole to another using a Ballard custom threading tool.

One of the distinct requirements of this project that sets it apart from other “wire saw cutting” operations is that Ballard performed a “hot tap” demolition in both the Suction Tie-in conduit and the Brine Line Discharge conduit. Water velocities exceeded six knots behind the vault, not allowing access to the back side. This required Ballard to design and fabricate tooling to feed the wire through the cored holes. Divers cut the block into two separate pieces. Three vertical cuts were performed first, followed by the bottom cut and completed with the top cut. To prevent the large concrete block from falling back into the channel, the block was rigged to a snatch block which was run back to the vault wall and then to the crane. When the final cut was completed, the wall piece was slid horizontally out of the block-out on a steel frame and into the center of the caisson. The block was righted and lifted vertically from the center of the caisson. After cutting operations were completed and the concrete block removed, divers covered all exposed rebar ends with Splashzone.

The Ballard team completed a 350ft (107m) penetration dive to inspect all three butterfly valves in suction blockhole.