Project Tag: Engineering & Technology

Seawater Intake Lines – Modification & Cleaning

Global Diving & Salvage,Inc was the prime contractor / project manager responsible for the modification and cleaning of the SeaLife Center’s intake lines. The first phase of the project was to install a pig launcher system; tasks included dewatering the Center’s wet well,installing an isolation valve between the well’s chambers,and saw cutting new access holes in the pump room floor.

The second phase of the project consisted of the dive crew cutting a 24 inch HDPE pipe and lifting it out of the soft bottom material to allow for an ROV inspection of the intake pipe. The inspection was short lived as the pipe was impassable due to marine growth and sediment. In order to clean the lines,several cleaning pigs were launched to remove the blockage. A new intake screen and support structure was installed along with a remotely operated pig catcher.

Dive crews worked off of a barge with a 150 ton crane and four point mooring system that was strategically anchored over the buried intake support functions. A deep gas dive system was utilized to accommodate dive operations in up to 260′ of seawater. The final quality control inspection was performed by an ROV flying over 200′ up the pipe to inspect for marine growth and debris.

Beachwalk WWPS decompression chamber

Global Diving & Salvage, providing Hyperbaric Consulting Services,including assistance with drafting of Hyperbaric Intervention Plan of the Beachwalk WWPS project in Honolulu,Hawaii. Global has also assisted with the design,procurement,and modification of a decompression chamber that will be used in the event that a hyperbaric intervention becomes necessary during the digging of the force main portion of the project. The new tunnel,7 feet in diameter will be bored with a micro-tunnel machine. In the event of need for hyperbaric intervention,a bulkhead will be installed near the opening of the tunnel,the decompression chamber will be mated to the bulkhead and the compressed air workers will enter the tunnel through the decompression chamber. They will decompress on the way out,if needed. Global will provide supervision of the hyperbaric events.

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.

King River Powerhouse Repairs

Global Diving & Salvage,Inc. has been contracted by Pacific Gas & Electric to perform repairs on the 150 foot tall vertical surge shaft of the King River Powerhouse. Repairs include placing a priority underwater epoxy over potential areas of water seepage on the shaft wall. The divers are working 60 feet below the top of the shaft,in 40 feet of water. The divers are being lowered through the dry vertical portion of the shaft,a confined space,to perform the repairs.

Brightwater – West; Hyperbaric Tunneling Support

Global Diving is providing complete hyperbaric intervention support,including training of compressed air workers,manlock and medical lock operators,as well as assisted with the design and installation of mixed gas breathing systems in the chambers located on the TBM (Tunnel Boring Machine). Global also procured and modified an existing Medical Chamber as well as purchased a standard deck decompression chamber and designed and modified the chamber to serve as a hyperbaric shuttle to move personnel from the TBM to the medical chamber if needed. Global developed the hyperbaric manuals and decompression tables and provided assistance to the J.V. on pursuing and acquiring variances for the project.

Pit 5 Instream Flow Release Modifications

Global Diving & Salvage,Inc. was contracted to install nine 18” x 44” outlet gates on the upstream face of four existing wheel gates. The design required that the new gates be installed in a water depth of 20’. To accomplish the work Global provided engineering and cofferdam design of two 25 foot tall cofferdams which had a radius of 4’. The cofferdams were fabricated in the bay area and shipped to site where they were utilized.

To accomplish the work Global certified underwater welders installed pad eyes on the upstream face to attach turnbuckles. Willliams undercut anchors were also installed to provide hold down capabilities. After installing the cofferdams and working under confined space and fall protection regulations Global’s surface welders cut openings and installed bow outlet pipes,gates,and operator platforms on the upstream face. The work progressed and the cofferdams were moved from site to site. All work was tested and installed to clients high expectations. The work was completed on time and within budget.

Pit 4 Cofferdam Installation

Global Diving & Salvage,Inc. provided a dive crew to install and seal a 25’ x 15’ wide cofferdam to the face of Pit 4 Dam. The installation required the removal of 5.5 cubic yards of concrete. To accomplish the removal the divers utilized rivet busters,sinker drills and rock splitters. After removal of the concrete the cofferdam was installed with almost 40 epoxy anchors which were pull tested prior to tightening. The cofferdam is being installed to allow for a new 8 foot diameter penetration and gate through the existing dam. A new intake structure will subsequently be installed.

Cheesman Dam Upstream Control Project – Phase 1

Cheesman Dam,located at 6,842 feet of elevation,is a primary reservoir for Denver Water who provides the potable water to Denver,CO and surrounding areas. Completed in 1905,it was built by Italian Master Masons using finely set and mortared granite blocks. Cheesman was a technological masterpiece and landmark of civil engineering for decades to come.

The Upstream Control Project,Phase 1,encompassed the replacement of three internal gate valves with new hydraulic slide gates located on the upstream face of the dam. The first step was to upgrade the existing Auxiliary,Mid and Low Level outlets,located at 60′,150′,and 200′ deep respectively.

Diver’s worked off of 80-foot by 80-foot sectional barge platform on the reservoir. Due to the depth and the amount of work required a combination of surface and saturation diving was utilized. The Auxiliary level work was done using surface supplied air while the mid and low level outlet work was done using saturation diving.

The original bypass outlets,tunneled through the canyon wall,were enlarged to accept new stainless steel spool pieces,one weighing 29,000 pounds and other two weighing 14,000 pounds each. Divers drilled holes at predetermined location and used underwater explosives to enlarge the openings to accept the new spool pieces. The spools were installed just inside the canyon wall,secured in place with epoxy anchors drilled into the native material,and securely grouted to provide a leak free seal. The new stainless steel slide gates were then mounted to the face of the spool pieces and protected by trash racks to prevent rubble from entering the intake system.

The new valves are operated from a new control structure built on the crest of the dam. This structure houses the hydraulic pump unit and controls which operate the valves. To connect the hydraulic tubing to the valves,holes were drilled from the crest of the dam,exiting into the reservoir next to the gate locations. Hydraulic tubing was installed into the holes and secured in place with grout,connecting the controls on the surface to the individual valves.

Bull Run Dam

In 1929 the City of Portland built Bull Run Dam 1 on Federally protected and restricted land,the Bull Run Watershed. This complex,Bull Run Dam 1 and 2 is a significant source of potable water for the City of Portland and the surrounding area. Due to its location of Federally protected land and fact that we are working in potable water great care has been taken during the project,from complete decontamination of all diving gear and related equipment that enters the water,to complete containment for all mechanical equipment on site. Access to the site is extremely limited,there is no thru access across the top of the dam,all of the equipment had to be staged on top of the dam. The water level has fluctuated over 40 feet during the project,making access to the water extremely difficult.

The dam has seven slide gates mounted to the face of the dam inside a trashrack enclosure. These gates,located at various levels allow the operators the control the flow of water as well as the level (temperature) of the water as it moves through the system. During the project the existing trashracks as well as the supporting beams were found to be severely rusted. They are all being replaced with new galvanized beams and panels. One existing gate,#6 had severely eroded concrete behind the frame where it mounts to the dam wall allowing water to pass even when the gate was closed. Part of the project was the complete removal of the gate,drilling out of the original anchor bolts,repair to the concrete and reattachment of the gate to the dam. This entire process was carried out inside of the trashrack enclosure Tracks were mounted to the underside of the enclosure and the gate was moved to the outside edge where it lifted and set on deck for cleaning and storage while the concrete repairs were being made. The gate was reinstalled and secured with new anchors.

The existing materials were all the original installation,the nuts which secured the stem to the gate were severely corroded and had to be cut off. All of the existing stems were removed and disposed of as well as all of the stem guides and the actuators mounted on the surface. New stems guides were mounted to the face of the dam. New stems were attached to the guides. As stated above,all of the work was carried out inside of the trashrack structure,all of the parts and pieces had to be lowered into the water then cross hauled under the overhead structure and lowered into place. Once installed through the operator floor the stems were attached to new operators and connected to the gate itself. All gates were fully function tested for proper operation.

Part of the project also involved repairs to the spillway. Rolling scaffolding was raised and lowered on the curved spillway surface as needed to access the area to be repaired.