Project Tag: Marine Construction

Rocky Reach Spillway Apron Underwater Concrete Repair

We were contracted to preform an underwater concrete repair to the spillway baffle under spill gate 3,and preform an inspection of the spill way and dentate from spillway 2-8 and 9-12. the spillway was separated into two sections by a fish ladder between Bays 8 and 9. The perimeter of the eroded areas were delineated using an U/W track creating a key way,ensuring a minimum depth of repair,throughout the area. Divers used rivet busters to remove concrete from the key cut as well as from under exposed rebar to ensure encapsulation and to allow couplers and new rebar to be added in areas wee eroded. Divers then used a 20k hydro blaster to wash away loose material and marine growth. Once the areas were prepared and cleaned,custom form tops were installed. The forms were made to fit the round side of the baffle that was approx. 18’x20′ and was rock anchored in place. Eight cubic yards of high strength concrete was then pumped into the form. While the concrete cured in the forms,the inspections were carried out of the stilling basin floor. The forms were removed and the project demobilized.

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.

ROV Makes Deep Sea Pipe Repairs

Global’s Cougar and Falcon ROV systems were mobilized to Hawaii to facilitate repairs on the 40” coldwater pipeline transition section in 500 feet of water off of Keahole Point on the island of Hawaii for the Natural Energy Laboratory of Hawaii Authority (NELHA).

The 40” pipeline is unique in the fact that it is installed with gravity anchors to a depth of 457 feet and from there to a depth of 2000 feet it takes the form of an inverted floating catenary. An installation error when the pipeline was originally installed in 1987 led to future failures of chain bridals and anchor chains. In addition growth on the pipeline was weighing it down.

The ROV crew,operating off of the Healy Tibbitts 544 crane barge,was tasked with restoring the pipeline to an as designed condition. The Cougar ROV cut loose and replaced two 500 foot 1-1/2” stud link restraining chain bridals. The pipe had to be cleaned and obstructions cut loose for the installation of new pipe clamps in three places. 1-1/2 tons of flotation was added at each clamp location. Two 1-1/2” stud link chain bridals were added at the bottoms of the clamps and secured to a 40 ton gravity anchor. A 1-5/8”stud link chain bridal was added to the offshore bridal. Special underwater tooling was designed and manufactured including a hydraulic chain tensioner,3-1/2 and 10 ton winches and 40 and 48 inch hydraulic actuated pipe clamps that were tested in Seattle before being deployed to Hawaii.

Horse Mesa Dam, Units 1 – 4 Intake Repairs

Global Diving & Salvage,Inc was contracted by Salt River Project (SRP),operator of Horse Mesa Dam,located 65 miles northeast of Phoenix,AZ,to provide project management and diving services to make repairs of Units 1 through 4. The work on Unit 4,located in 160 feet of water,and on Units 1,2,and 3,located in 260 feet,necessitated the use of saturation divers.

Saturation diving is a method where divers live at a pressure equal to the depth they are working and transit to and from the work area via a diving bell. When not working,they live in chambers that are located on the deck of the barge. A crew of 21 working in two 12-hour shifts are required to support both the divers on deck and those in the water. In saturation diving,decompression is not eliminated; it is delayed until their rotation is over,which is usually 30 days. On this project,it took three days to decompress from the working depth to the surface.

In June 2012,a vertical concrete guide vane located in Unit 4 failed. Divers removed the remaining sections of the damaged vane as well as a second still-intact vane,using wire saws and wall saws. A new steel vane system,consisting of two vertical and nine horizontal vanes,was installed in place of the original concrete structures. The vanes were bolted in place and then filled with grout for added stability. New trashracks were installed in the intake. The bulkheads for Units 1,2,and 3 did not seal adequately to the penstock intakes due to deteriorated concrete on the intake opening face. Divers anchored and sealed new steel sealing frames at each intake location. Inspection also discovered deteriorated concrete at various locations in the three sets of gate guide slots on the upstream face,which was repaired.

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.

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.

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.

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.

Avon / Tesoro Wharf Pile Repair

The existing timber piling on two bay area refinery piers are showing signs of deterioration and marine borer activity. To preserve the remaining integrity of the piling we are installing fiberglass jackets onto the deteriorated piling,the annular space is then filled with grout. On one of the wharf’s,there is an outfall pipe that was temporarily relocated while the fiberglass jackets were being installed. The outfall pipe was resecured along with horizontal timber supports.