Project Tag: Deck Decompression Chamber (DDC)

Rock Island Dam Adult Fishway Extension

Rock Island Dam is located on the Columbia River,approximately 15 miles south of Wenatchee,WA. The development of a crack in a spillway of Wanapum Dam,downstream of Rock Island Dam necessitated a 25 foot drawdown of the tailrace. This created a significant obstacle for the fish migrating upstream; they would not have access to the original fish ladder. With the arrival of the migrating salmon just a few months away,this project took on a critical path very quickly.

Chelan County PUD,owners of Rock Island Dam,contracted Knight Construction from Spokane to install the emergency fish ladder extensions in three areas,two on the west bank and one on the east. Knight,who handled the fabrication and topside support,turned to Global Diving & Salvage,Inc. to provide the diving support for the project. With the compressed schedule required to complete the project,Global and Knight worked closely on scheduling the arrival of the fabricated items and their installation.

The extensions,similar to the structural components of the original fish ladder structure,consisted of steel boxes and flumes used to create pools and steps. These new boxes and flumes were mounted to the face of the dam and in the case of the east side,were suspended from a pipe that spanned two pier noses. The project involved a wide array of construction techniques,including; core drilling,setting of epoxy and mechanical anchors to secure the boxes and frame work in place,wall sawing to remove sections of the dam to allow access at the lower water levels. The steel sections were bolted and in some cases welded in place.

By all accounts the project has been a great success. According to the Wenatchee World,over 20,000 of the expected record 235,000 Chinook salmon migration have already traveled upstream past Rock Island Dam.

Skagit River Bridge Collapse

On Thursday,May 23,2013 while traveling on the southbound lane of Interstate 5,a truck hauling a heavy and oversized load struck the support structure of a bridge crossing the Skagit River in Mt. Vernon,WA. The damage inflicted by the truck caused the 160 foot long four lane span to collapse into the river below,completely severing the north and south bound lanes of the major west coast interstate highway.

Global Diving & Salvage,Inc.,under contract to Atkinson Construction,worked around the clock for 13 days under direction of the Washington Department of Transportation and the National Transportation Safety Board (NTSB) to provide diving and salvage services throughout the investigation and debris recovery phase of the project.

Dive operations in the river were complicated by high river currents resulting from spring runoff conditions. The salvage operations included a detailed underwater survey of the downstream edge of the wreckage to ensure that it was safe to bring demolition equipment alongside. Motor vehicles caught up in the collapse were recovered. Working closely with the NTSB the bridge wreckage was cut and rigged out of the river. With the river cleared of debris,an underwater inspection of the concrete bridge piers was performed in order to confirm the structure remained viable for bridge reconstruction.

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.

Water Treatment Plant – Intake Installation

The City of Austin,Texas installed a new water treatment system to supply water to the growing city and surrounding area. Global Diving supported the installation of piling,lake tap structure,and piping / screen segments.

Pipeline Abandonment

Global mobilized a four point mooring system and a deep air diving system onto a landing craft. The vessel was then moored 40ft from the leg of a production platform and directly over a sub sea oil and gas manifold. This required anchor operations to conducted in 3 pipeline corridors and near an active production platform. The project involved installing several hot tap installations and disassembling and re-assembling various spool pieces of the subsea manifold,which aid in the ability to utilitize cleaning pigs in both lines from the platform. All this was done without interrupting flow thought the manifold or operations on the production platform that it is connected to. This project was performed in Cook Inlet that is typical has zero visibility and tidal current in the excess of six knots

USCG – Orphan Well Leaker

Mobilized surface dive spread and light construction vessel(s) to conduct site clearance operations on a leaking well at Main Pass 25. Conducted diver and sonar (Mesotech 1000) survey of bottom within 100′ radius of well center. Identified and removed (3) 2″ pipelines and misc. debris from bottom in preparation of lift boat arriving on site to perform well abandonment operations.

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.

Platform Decommissioning

Working aboard the D/B Superior Performance,we provided mixed gas diving support to WWCI for the removal of an 8-pile platform jacket. Diving operations were conducted to a depth of 218 fsw. Due to internal obstructions,divers utilized diamond wire saw tooling to cut two of the jacket legs. The remaining legs were cut utilizing underwater burning rod.

Dix Dam Face Slab Repair

Upon completion in the mid 1920’s,Dix Dam was the largest rock filled dam in the world standing approximately 287 feet above the riverbed. It was built in the private sector by it’s current owner,Kentucky Utilities Company,to create a reservoir for operating a hydroelectric generating station.

Global was selected to perform and manage repair work to an existing earth filled dam. Divers removed debris including cars,trees,and sediment from several areas of the dam and then these areas were surveyed using sonar and tactile methods. Damaged areas of the face slab were covered using sheet membrane secured to the face of the dam. Work took place in up to 140 feet of water.

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.