Mooring Dolphin Concrete Removal

A 745-foot propane tanker was in the process of mooring at the Alcoa Intalco Works Gas Terminal in Ferndale, WA when it contacted a terminal pier, suffering hull breaches and knocking a pile cap from the pier into the ocean. 

Scope of Work
Ballard was responsible for the demolition and disposal of the damaged forty-foot by thirty-foot by five-foot thick, 450-ton pile cap in fifty feet of water. The team conducted underwater demolition operations including wire sawing, concrete coring, installation of drilled epoxy anchors, and heavy lift rigging.

Innovative Solutions
The forty-foot by thirty-foot by five-foot thick concrete pile cap was saw cut into three sections using a diamond wire saw. Divers completed dredging and jetting to install temporary conduits under the pile cap to guide the diamond wire into position. Additionally, divers core-drilled relief holes and anchor bolt holts to epoxy in place, lifting pad eyes. The block sections were removed using an engineered two-part rigging method. First, rigging into the pad eyes to relieve suction and place on a pre-staged belly strap chain underwater and second, by removing the block from the water with the chain belly straps.

Ballard completed the demolition and disposal of the concrete blocks after transporting the blocks to a marine yard offsite.

Client: Petrogas
Location: Ferndale, WA
Diver Depth: 50ft


• Demolition
• Heavy Lift Crane Operations
• Surface Supplied Air Diving
• Underwater Inspection
• Underwater Cutting/Welding
• Underwater Diamond Wire Sawing
• Underwater Excavation