Project Tag: Pacific Northwest

Richmond Beach Outfall Repair

We provided all project management,diving services and topside support for this location as part of an overall three-outfall repair project. Work done at Richmond Beach involved the moving of approximately 50 cubic yards of sediment that had accumulated around the existing diffuser flange. Once the flanges were exposed,the bolts were cut off using a Broco underwater cutting rod. The original steel diffusers were raised to the surface and new HDPE diffusers were installed.

The work was done in 150 feet of water,with divers using surface-supplied air.

Robson Bight Salvage

Global Diving & Salvage,Inc. and Mammoet Salvage of Holland performed a highly technical deep-water recovery of a fuel-laden tanker trunk in the sensitive waters of the Robson Bight Ecological Reserve at the northern end of Vancouver Island,British Columbia. The reserve is considered critical habitat for the resident Orca (Killer Whale) populations along Canada’s west coast. The work was performed directly for the Ministry of Environment,British Columbia.

Working at a depth of 1,165ft using Global’s Cougar Work Class ROV,divers,and a specially engineered Deep Water Recovery Casing (DWRC),the team carefully and successfully recovered the sunken tanker truck laden with diesel fuel as well as a container containing assorted oils and hazardous materials from the sea floor. The operation was completed safely and with no additional impact to the environment. How it happened.

Carkeek Outfall Repairs

We provided project management,diving and topside services as required to perform work on all three outfalls of this contract. The work on the Carkeek outfall was performed in approximately 200 feet of water. The work was carried out from a flat-deck barge that had been outfitted to perform deep-diving operations. The barge was moored on location with a four-point anchor system,allowing the barge to be positioned directly over the work at any point along the diffuser section alignment.

The project required the removal and replacement of all 11 of the existing steel diffusers. The four bolts per flange were burned off using a Broco underwater cutting rod. Once the existing diffusers were removed,we noticed that the interior of the pipe had filled approximately half-full with sediment. This material was removed with an air lift. The nozzle was inserted into the end diffuser,and once the surrounding materials were removed,the remaining sediment in the pipe was jetted to the air lift using a pressure washer to move the materials. When the pipe was clear of the sediment,the new diffusers were installed using stainless steel hardware,connecting the new diffuser flange to the existing outfall flange.

Due to the depth of the work,divers used a mixed gas,Heliox (86% helium,14% oxygen). This combination allowed the divers to stay on the bottom longer while also negating the effects of nitrogen at increased pressure. The divers entered and exited the water via a dive stage. The stage is used to control the diver descent and ascent and allow the dive supervisor to control the the diver’s decompression stops. Once the diver had fulfilled his in-water decompression commitment,they were raised to the surface and put into the deck decompression chamber to complete their decompression.

Hood Canal Bridge Replacement

We were contracted by Kiewit to provide diving and ROV services to route the 3-inch galvanized steel anchor wires through the new concrete anchor blocks that support the new east half of the bridge. The anchors are located in 60 to 380 feet of water. The new anchor wire was pulled through an anchor and connected to the bridge where the proper tension was achieved. Each leg of the two wires that attach to the anchor block has a tensile strength of over 1 million pounds. The anchors themselves weigh over 2 million pounds each. The project required the placement and connection of 20 anchors to secure the bridge in place.

Our divers connected the new anchor lines to the messenger lines that were in place and observed that the new wire,as it was pulled through,did not kink or get bound up. On the deeper anchors,the Cougar XT ROV was used. This vehicle,equipped with two five-function manipulators,was able to make the required connections and had enough power to stay on station during all but the heaviest currents.

Boat Ramp Upgrade

The project required replacement of an existing woodpile-supported boat launch. The ramp was located along side the causeway and adjacent to the product lines used to move products to and from tankers and barges moored at the end of the pier. Lifting and removing the existing materials,driving the new steel pile,and setting the new ramp structure all had to be done from the water. We hired Culbertson Marine of Anacortes,WA to provide crane support from their barge,which was moored just offshore of the ramp.

The ramp was removed in several pieces and set aboard the barge for further disassembly. The pilings were obstructed by riprap that was placed as armor along the shore. Rocks had to be individually rigged and set aside with the crane. Once the pilings were exposed,they were cut off at the mud line. New steel piles were driven adjacent to the old piling locations. The steel pilings were cut off at the proper grade,the new ramp was assembled in sections,and then lowered over the new pilings and secured in place. Once all pieces were in place,the track was installed. An alignment fixture was used for proper spacing of the tracks to allow the cart supporting the boat to move freely.

The work was done in an intertidal zone,with divers working above and below the water as the tide came in and out and the work progressed either in- or offshore.

The Dalles Bay 8/9 Spillwall

We were contracted by Kiewit to provide diving services to assist with the installation of a wall between Bays 8 and 9 of The Dalles Dam on the Columbia River. The wall is intended to redirect the salmonids that are migrating downstream and increase their survival rate.

The wall is 10 feet wide and over 800 feet long,the last 150 feet of which is at an angle to direct the water flow into a deeper portion of the river. It is constructed of precast concrete segments that were installed in the spillway and onto a leveling slab built on the river bottom. The segments were set in place and leveled using jacking rods. Once level and in place,the next segment was brought in and the process repeated. After several of them were in place,divers tied the segments together with rebar dowels. Forms were then installed on the joints between and around the bottoms. Concrete was then tremied into the segments. This process was repeated across the stilling basin.

Where the wall extends beyond the stilling basin,a 15-foot-wide leveling slab was installed. The river bottom was cleaned of loose debris. An area that ran across the path of the wall was excavated,because the underlying rock was fractured and non-competent. Form work was lowered from the surface and fit to the bottom contour. Rebar doweling was drilled and epoxied into the river bottom where needed. Rebar mats were installed inside the form work. Concrete was again tremied in place.

The wall has been carried over onto the leveling slab in the same manner as on the stilling basin.