Project Tag: Marine Construction

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.

Olmsted Lock and Dam

We have been contracted by the Washington Group to provide diving and dive related services as required in the building of Olmsted Dam on the Ohio River. After studying various dam construction methods,the Corps of Engineers (COE) decided to use an innovative method known as “In-the-Dry” for Olmsted Dam. Basically,sections of the dam known as shells are prefabricated on shore in a precast yard and carried out into the river and set in place. The dam consists of two primary areas; the tainter gate section and the navigable pass section.

Eleven Mile Canyon Dam Gate Repair

Located approximately 70 miles southwest of Denver,Colorado at an elevation of 8,602 feet,Eleven Mile Canyon Dam is owned and operated by Denver Water. The gates were located at a water depth of approximately 104 feet. Converting for the elevation,divers were exposed to an equivalent water depth of 140 feet.

Divers performed work using a combination of standard air and Nitrox. Tasks included the removal of the stems and guides from the face of the dam. Once the stems were removed,the gates were brought to the surface where the existing hardware was removed and the gate pressure washed. New stainless steel stems,guides and couplings were then installed.

Mercer Island Sewer Line and Pump Station #4 Replacement

The existing sewer line on the northwest corner of Mercer Island was installed in the mid-1950s,and is constructed of asbestos-cement (AC) material. The line has been suffering ongoing pipeline deterioration,capacity deficiencies,and other operation and maintenance problems. Manson Construction was awarded the contract to replace this portion of the sewer line with cast iron pipe and selected us to provide the diving services. This project will extend over a two-year period and involves the replacement of over 7,000 feet of pipe with 32 side sewer connections.

We are working very closely with Manson during all aspects of the project,including: installing both gravity and force main pipes,aligning and connecting the side sewer piping,assisting with hand dredging under docks and in tight areas where the derrick cannot access,and making the physical transition from the existing line to the new piping.

Alki 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 Alki involved the installation of five new anode sleds. Tabs were welded to the existing outfall,and leads connected the new anode sleds to the outfall. At the conclusion of the installation,measurements were taken at 22 locations along the outfall to verify the increased cathodic protection.

Welding was performed in 100 feet of water,as was setting of the five anode sleds.

French Meadows Low-Level Outlet Cylinder Replacement

We performed emergency repairs to a leaking hydraulic system. The repairs were completed at a depth of 175 feet at an elevation of 5,400 feet. With altitude corrections,diving depths were equivalent to 200 feet. To accomplish this task,we mobilized all aspects of a mixed-gas diving spread to French Meadows Reservoir in December,2006.

Together with PG&E personnel,we replaced the existing 14″ hydraulic cylinder and portions of the existing lines. After the replacement of the cylinder,the new cylinder and hydraulic required less than 1/3 of the original hydraulic pressure to operate the gate.

The project was conducted over a three-week time frame involving 25 dives without incident. We were responsible for providing cranes,barges,and environmental controls for the operation. The operational considerations included -30 below zero temperatures and extreme snow accumulations. A major concern of all parties was the potential release of hydraulic fluids into the lake.

All diving and operations were conducted safely and without incident in the extremely harsh deep-diving environment. Environmentally,the project was conducted without incident.