P.L.E.M. Buoy Replacement – Phase 1
March , 2013
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.