Project Tag: California

Line 400 Depth of Burial Survey

The purpose of this survey was to determine the elevation of the two 26″ pipelines that comprise the Line 400 Sacramento River pipeline crossing,and the 22kV cable river crossing at the Rio Vista Bridge. After being uncovered by the Derrick Barge,which utilized a 12″ Air-Lift,Global was contracted to take pneumofathometer readings at the top of the pipes. This was necessary in order to identify the cable and pipeline depth for upcoming navigation channel dredge work. If pipelines were established to be at too shallow a depth,the pipeline and cables will subsequently need to be relocated.

Avon / Tesoro Wharf Pile Repair

The existing timber piling on two bay area refinery piers are showing signs of deterioration and marine borer activity. To preserve the remaining integrity of the piling we are installing fiberglass jackets onto the deteriorated piling,the annular space is then filled with grout. On one of the wharf’s,there is an outfall pipe that was temporarily relocated while the fiberglass jackets were being installed. The outfall pipe was resecured along with horizontal timber supports.

Pile Cutoff at Hunters Point

We were contracted to survey,locate,and burn off an assortment of 20 inch diameter steel pilings,during the demolition phase of a pier at an old US Navy Base at Hunters Point in the San Francsico Bay; a ‘superfund’ site clean up. A four-man crew was dispatched and spent 2 long days searching in zero visibilty conditions,marking targets with buoys,and eventually cutting off and retrieving the piles,which ranged from 10′ to 38′ feet long.

Olive Ranch Valve Replacement

We were hired to perform a 12″ valve replacement located in a briney pond at an olive ranch. The first task was to remove a trash screen so that one of our divers could entered a vault,burn off 12 bolts,and replace an existing 12″ slide gate valves with a blind flange until the new valve could arrive.

Upon delivery the two new valves,the dive crew will return,take off the blind flange and replace it with a new valve. In addition,a second old valve will be removed and replaced.

High Elevation Relief Reservoir Maintenance

We were hired to install blanking flanges on the upstream end of a high altitude dam in 150 ffw so our client could perform maintenance on the three valves in the outlet works piping of Relief Reservoir.

This remote reservoir is located in the Sierra Nevada Mountains at an elevation of 7,300 ft with no road access to the facility. All equipment and materials for this site is brought in by helicopter or mules. Due to the high elevation and depth of dive operations mixed gas diving was the primary form of diving employed to maximize working bottom time. Due to the greater decompression requirements of mixed gas techniques decompression chambers are utilized to ensure the diver’s safety.

A heavy lift helicopter (Sky Crane) was brought in to transport sectional barge pieces since the the crest of the dam was not wide enough for the dive equipment. Each piece was 15 ft by 7 1/2 ft and weighed over 8,500 pounds. Together they created a 30 ft by 45 ft dive barge. The heavy lift helicopter then lifted two decompression chambers and a dive van from the staging area in Kennedy Meadows to Relief Reservoir,a five minute flight.

Helicopter operations included a comprehensive security plan as the staging area is a high traffic tourist site for pack trains and hikers.

Balch Camp Dam Low Level Outlet Gate Repair

Our California region was contracted to assist with repairs to a 30” low level dam outlet gate. Phase 1 of the project included silt relocation efforts and a ROV inspection to monitor the progress. During phase 2,divers removed and replaced the existing cylinder after repairs to the gate.

Diving depths were in the range of 100 ffw at an elevation of 3000 ft. Due to this elevation and water depth combination surface decompression was utilized.

McCumber Dam Cylinder Replacement

We provided a four man dive team and all equipment to perform the replacement of a hydraulic cylinder and hydraulic lines at McCumber Dam. The replacement required underwater welding of support beams in 25 feet of water. The replacement was made difficult due to the elevation and winter conditions.

Bay Tunnel – Ravenswood Portal

We have been contracted to assist with the underwater construction of a launch portal for the new Bay Tunnel. Diving is being conducted to depths of 130 fsw in zero visibility. The crews are installing rebar dowels,rebar mats,and assisting with the tremmie pour of a ten foot thick concrete floor. After the tremmie pour is complete the shaft will be de-watered in preparation for the tunnel construction. Upon completion of the shaft the horizontal tunnel under San Francisco Bay will be drilled with a Tunnel Boring Machine.

Spill Support for Sunken Tug

Global Diving & Salvage was contracted by a local dredge company to clean up oil spilled from a sunken tugboat near Pittsburg,CA. The Global crew deployed containment boom,sorbents,and a skimmer to contain and recover the oil that spilled from the tug. After the tug owner re-floated the vessel,Global crews defueled the vessel and removed over 3,000 gallons of oil and water from the bilge to a Baker tank onshore.

Abandoned Recreational Vessel Salvage

Global Diving & Salvage,Inc. was contracted by the Vallejo Marina to raise a 42’ sunken vessel and to respond to pollution released as a result of the sinking. Oil containment boom was deployed around the sunken vessel while divers placed heavy lift straps under the hull of the vessel. CS Marine of Vallejo,CA provided a derrick crane which was used to raise the vessel to the surface while the Global crew dewatered the vessel and conducted damage control. The vessel was towed to a nearby haul out facility where it awaits demolition and disposal.