Services

Tasks are as diverse as lock reinstatement, sealing turbine tunnels, video and still photography, surveys, stop log placement, underwater concreting and grouting, pipeline construction, pylon cutting, demolition using underwater cutting and explosives techniques, dredging, salvage, underwater welding, the cleaning of potable water reservoirs and tasks completed in contaminated environments.

Major Projects

Structures

• The Hume Weir - Dartmouth Dam - Yarrawonga Dam - Torrumburry Weir, Eildon Reservoir, Chitchester, Corrin and Bendora Dams. Diving in overhead environments under the trash racks and inside turbine tunnels. Sealing the gates using hydraulic and pneumatic power tools in depth up to 40m. These dives usually require a decompression chamber to be located on site. Descend services over 30 headworks reservoirs for Goulburn Murray Water.

Construction

• Murray River locks ten and fifteen at Euston and Wentworth are removed any time the river floods. Descend Divers have reinstalled the locks consisting of fifty needle beams, weighing approximately one tonne each. This job has been done on several occasions always in nil visibility and a current of approximately four knots.
• The Jindaybine East water scheme was a Public Works Department project that required the placement and securing of three thirty metre, 450mm diameter, inlet pipes onto pylons, connect the trunnion, grout the pipes, drill in rock anchors and jack hammer and air lift rock obstructions.
• An old trash rack was removed from the low level outlet at Eildon weir and replaced with a new trash rack. This project required the use of Hot Water Suits, hydraulic cutting equipment and video surveillance. A recompression chamber was positioned on site.
• Bell ends were fitted to the hydro outlets at Chitchester Dam north of Newcastle, in 36m of water. Each flange weighed 280kg and was hoisted by Descends own workboat. The project was completed in cold water and low visibility ahead of time and under budget.
• A project at Corrin Dam near Canberra was completed for ACTEW in 2002. The job involved rectification of a water leak through the internal wall of the inlet tower and was controlled by bolting on a flexible membrane attached to a stainless steel frame. The attachment involved drilling 30 holes in reinforced concrete and fitting chemical anchors at a depth of 25m, and required over 26 hours of in water time.

Explosives

• Explosives were used by Descend to clear obstructions in a Wodonga Creek for the positioning of an inlet pipeline. Electric detonation on the surface was used to ignite detonating cord to fire the main charge. Descend is licensed to use explosives in N.S.W., Victoria and ACT.

Surveys

• Descend has surveyed all of the bridges on the Murray River in NSW for the RTA.
• The internal surfaces of the Hume Dam turbine tunnels required complex and accurate measurement for the design of the new inlet baulks.
• The public works department required a complete survey of a road bridge at Echuca to ensure no navigable hazards existed in the waterway.
• The Warringa outfall was surveyed for structural defects and detects were poured with CA80 grout.
• Descend was contracted by Goulburn Murray Water to survey seven dams in Victoria as part of an on going asset managed program.

Contaminated Diving

• The Falls Creek sewerage system required divers to correct machine malfunctions in the raw sewerage settling tanks. This dive was an elevated altitude dive.
• The Australia Paper Mills required divers to remove foreign objects from a wood pulp settling tank.
• The Albury City Council contracted Descend to survey pumping equipment at the Albury Sewerage Works in their primary holding tanks.
• Descend regularly conducts dives where levels of blue green algae are present.

Welding and Cutting

• The collapse of a levee bank at the construction site of the Yarrawonga Power Station, required Descend Divers to position and weld RSJ strengthening beams into place in nil visibility. The welding was completed using Broco soft touch rods, powered by a 400 amp D.C. generator. Over 100 railway lines have been cut out of the Murray River at Khancoban using a Broco ultrathermic cutter.
• When positioning a half tonne trash rack on an inlet pipe in the Murray River a Broco ultrathermic cutter was used to remove 15 brackets incorrectly left on the original pipe.

Concreting and Sandbagging

• A leaking levee bank at Torrumburry Weir was successfully sealed using sandbagging techniques and a ten cubic metre pour of pumped concrete.
• The bottom of the weir at Torrumburry was stabilized using geo-fabric matting and poured concrete techniques.

Dredging

• The Ellis Williams Power Station at Tumbarumba requires divers to use a 6" water dredge to shift approximately ten cubic metres of soil and rubble created by a land slip, to enable the inlet gates at the turbine to be closed for repair. The job was completed in nil visibility and a water temperature of six degrees celsius.
• Albury City Council and Corowa Councils, have both used Descend to dredge out water inlet pipes for their water supply inlets.

Potable Water Storages

• Goulburn Valley Water regularly use Descend to clear their town water reservoirs at all locations in central victoria. This specially designed equipment allows the reservoirs to be cleaned while still in operation and with a minimum of turbidity.

Salvage
 

• In 2003, Descend salvaged the Whyma ferry for the RTA when it sunk in the Hume Weir.
• Descend has located and salvaged numerous boats, motors, agricultural machinery, drilling rigs and other large objects under adverse conditions.

Video

• Complex video inspections have been completed on the Hume Weir and Yarrawonga Power Station and numerous dams throughout N.S.W. and Victoria and is a normal part of our quality control assurance.

Demolition

• Descend has demolished old road bridges at Howlong and regularly uses underwater chainsaws to remove old piles.

Major Customers Include

• Pacific Power
• Snowy Mountains Authority
• Department of Water Resources
• Albury City Council
• Wodonga City Council
• North East Regional Water
• Wagga City Council
• Echuca City Council
• Beechworth Council
• Rural Water Corporation
• John Holland Construction
• Baulderstone Horniebrook
• Kilpatrick Green
• Goulburn Murray Water
• Goulburn Valley Water
• Hunter Water
• RTA
• ACTEW
• Transfield Boygue
• Transfield China Harbour