Project Tag: California

Legacy Wells Plug & Abandonment

Global was contracted to plug and abandon legacy wells at Treadwell 10 and North Star 815 sites near Summerland Beach, CA. Global dive teams had conducted assessments of the sites on separate prior occasions to determine the exact location and manner of the oil seepage. Two 4-person dive teams working 12 hour shifts located the …

PLEM Buoy Replacement

A dive team from our California Regional Office was deployed to Okinawa,Japan to assist Truston Technologies,Inc. in constructing as-built drawings of an existing PLEM (Pipeline End Manifold). The buoy and related piping are in 75 feet of water,approximately a half mile offshore from USMC Base Camp Courtney.

Phase I of a scheduled two-phase project involved complicated logistics to deliver a deep air diving system overseas,and to provide subsurface metrology solutions for the construction of a new replacement structure on the sea floor. While on site the existing steel components were carefully documented; ultrasonic thickness readings and corrosion inspection of the existing infrastructure was performed. The crew also inspected the existing Multi-Buoy Mooring (MBM) system; buoys,chains,and anchors.

During the inspections two abandoned ‘ghost’ pipelines were discovered. Topside sonar surveys had failed to detect these abandoned pipelines. It was imperative to the project to fully identify these in order to determine whether their location would interfere with replacement anchors and chain of the refurbished MBM system.

Phase II,scheduled for completion in 2013,will consist of the removal and replacement of the existing PLEM and SBM (Single Bouy Mooring). Information gathered during Phase I was be used for the fabrication and installation of new components.

Divers had to be mindful of the local poisonous marine animals while working underwater. Lion fish and the highly venomous stonefish had settled around the flanges and valves of the existing structure. The divers had to proceed with extreme care during the work,going so far as to remove all rocks on the seafloor in the vicinity of the work area in order to identify camouflaged stonefish.

Northern California Dive Bundle

Provided project management and supervision for three simultaneous projects,each with unique scopes,bundled into one contract. Project demonstrated Global’s ability to manage a complex project by assembling a command structure to oversee and facilitate the individual projects,at three remote job sites located approximately 70 miles from each other.

The command structure included; a Project Superintendent,acting as the single point of contact with the owner and providing continuity between the three job sites,a resident engineer to maintain the submittal roster as well as address unforeseen issues as they arose,and an administrative coordinator to monitor the submittal and paper flow that ensues with a project of this magnitude.

Over 700 dives were performed between the three job sites in water ranging from 25 to 205 feet at altitudes of up to 3,800 feet above sea level. Approximately 3,000 cubic yards of river debris was removed,50 cubic yards of concrete and grout were placed,and 150,000 pounds of steel were added.

El Segundo PLEM Buoy Repairs

Chevron has two product transfer moorings (PLEM),approximately 2 miles offshore of El Segundo. Global provided diving services and topside support for the replacement of hoses,buoys,and connecting components.

Cresta & Rock Creek Dam Survey

PG& E contracted Global to perform surveys of four concrete chambers at two separate Dams; Rock Creek Dam and Cresta Dam both located on the North Fork of the Feather River in Northern California. The concrete basins are approximately 25 feet wide by 124 feet long. Global divers accessed the structures through a trash rack and 48-inch inlet; which added an additional obstacle. The total penetration through the pipe and into the deeper area was approximately 35 feet,plus the additional 124 feet to the end of the chamber,necessitated an in-water tender for every dive.

A probe and a scanning sonar were utilized to conduct the surveys and determine the depths of the built up sediment. At Rock Creek,a Steel Wire Rope was established inside one of the chambers approximately 5 feet off bottom. This enabled an MS 1000 sonar to be suspended in order to scan images of the chamber every 5 feet for the entire length.

Inside the same trash rack a 24” pipe was inspected utilizing an ROV; two gate valves had been previously discovered by PG & E engineers to be non-functioning. These 24-inch pipes bifurcated about 25 feet inside the center pier and split off to both chambers supplying water to keep the gates afloat. It was suspected that the pipes and the valves were full of sediment deposited from upstream.

A thorough report providing the data obtained from the sonar images and the probe measurement was provided to the client upon completion of the project.

Inland Drilling Shaft Extraction

The contractor was digging multiple vertical shafts to a depth of 250′ in a vacant city lot in downtown San Francisco. These shafts are to form a ‘bulkhead’ to prevent soil movement,while excavation for a subway station and California’s future ‘high speed rail line’ is completed on the work site. The casings are filled with water during the excavation to resist surrounding ground pressure. During the extraction of a casing,the sections separated at three locations,120,145,and 170 feet.

Divers were lowered down the 84 inch diameter excavated casing in a man basket to a water depth of 170 feet. Repair options included welding the casing sections together or drilling through the section overlap and installing steel ‘plugs’ to lock the sections together.

The repair was successful and the casing was removed.

Refloating the Tug Tiger

The United States Coast Guard tugboat Tiger sank at her mooring at the Richmond Historical Pier in California. Global responded with 4 boats,2 skimmers,boom,and spill response materials to contain and remove the released containments.

Global was contracted to continue the salvage operations,utilizing an innovative plywood freeboard panel concept in an effort to refloat the Tiger.

Poe Dam Inspection

Divers set up templates and created an as-built drawing of the dam so that PG&E contracted engineers could fabricate a truss type stop log. This installation would support the work and repair of radial gates and additional work. A shallow air surface supplied dive spread was used to take many measurements using a custom designed aluminum jig.

Removal and Disposal of the F/V Tasu

Global mobilized salvage gear,an excavator,bulldozer,and waste bins to the site. A containment pit was dug in the sand upland from the wreck,and lined with 60 mil HDPE,and was then backfilled with sand. Sections of the boat will be pulled up into the containment pit to prevent pollutants from leaking into the sand beneath the liner. After the vessel has been demolished and transported for disposal,the beach will be cleaned,including any contaminated sand on the liner,and the liner will be removed. The beach will be graded back to its pre-existing condition prior to demolition.

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.