Designer of the Ord
KEN WEBSTER Boss of the Water Authority of WA, Born: London, 1928 Died: Claremont, July 2011, aged 82
Ken Webster, who died on July 9, had a long association with ANCOLD and ICOLD. Chairman of ANCOLD from 1985 to 1988, Ken was a regular attendee at ICOLD meetings and was a member of the advisory committee to the President of ICOLD. During his tenure as Chairman of ANCOLD Ken was responsible for setting up the first of the guideline committees that continue to work to the present.
The obituary published in the West Australian read in part as follows:
Kenneth Campbell Webster was born in London on September 11, 1928, the only child of sole parent Helen Webster. He grew up with his mother and grandparents in the tiny Scottish village of Edzell in Angus, north of Brechin. On graduating from Brechin High School, he was given a wooden box full of drawing instruments that influenced his desire to be an engineer.
Ken was granted a deferment for National Service and graduated as a civil engineer, after study at Aberdeen-based Robert Gordon College of Engineering and Aberdeen University. He then joined the Royal Air Force and after training he threw himself into his first job, investigating and designing a tunnel for a hydro-electric scheme in Scotland. His design for a viewing platform is still in use.
Two years later, he moved south to gain more experience in London, still a streetscape scarred by Hitler's blitz. It was while rooming with two engineer mates in an apartment in the attic of a mansion in Earls Court that he met Bunbury teacher June Winter, who was sharing a second-floor flat with two teacher friends from Perth.
They were engaged in 1954, but June had to return home to be with her mother. At the same time, Ken had final exams in August 1955 for admission to the Institution of Civil Engineers. Accordingly, June sailed home alone. She then paid £10 for her fiancé to join her on the assisted passage scheme. They wed at St Andrew's Church in Subiaco in October 1955 and Ken was introduced to WA on honeymoon in Yanchep and Geraldton. For nearly 40 years, they lived in Freshwater Parade, Claremont.
At 27, Ken sailed to Fremantle with ink still drying on his engineering qualifications. In Medina he worked for BP oil refinery but, when bored, joined the Hydro-Electric Commission in Tasmania as a designer for Catagunya Dam, the first pre-stressed concrete dam in that State. Already a family man, he put up with cramped living conditions, home in Hobart being a temporary bungalow comprising two rooms totalling less than 50sqm, about half the size of a small house today.
Many engineers migrated to Canada when work dried up but Ken joined WA's Public Works Department for the planning, design and investigation of the Ord Scheme Stage 1, aimed at creating Lake Argyle in the Kimberley to irrigate farmland around Kununurra. He worked in offices above the former Mortlock Motorcycle shop in Hay Street, West Perth. There was no air-conditioning and the design drawings were frequently blown about by fans or sodden by sweat. Relief arrived when Ken and his team relocated to a new office block, Dumas House, in Kings Park Road. In 1968, he flew to Israel on a Churchill Fellowship to study engineering projects relating to water supply and control.
After overseeing the planning and design of the Ord River Dam, one of the biggest projects in Australia's water history, in 1972 Ken went on to direct major expansions of many water schemes throughout Western Australia. During his time at the helm there were at least 8 large dam projects completed.
Ken went on to become Director of Water Resources in the Water Authority of WA and, when appointed acting managing director, was responsible for supplies for one third of Australia's land mass. On retirement in 1989 he became chairman of the board of the Water Authority for five years and, later, chairman of the Waters and Rivers Commission. In 1995 he was made a Member of the Order of Australia (AM) "for public service in Western Australia particularly the administration of water supplies".
It was an extraordinary finale to a story that began in an apartment in Earls Court in London.
Ken Webster had a chest infection and died in Alfred Carson Lodge in Claremont. He was 82. He leaves his wife and 4 children and 10 grandchildren.
Wellington Dam Remedial Works Project Update - November 2011
The Wellington Dam Remedial Works project was complete in August 2011 - some 4 months ahead of schedule and $4 million under budget. The last of the 43 post-tensioning anchors were stressed in July and the "wash-away" bridge deck was commissioned in August before minor site tidy-up works were complete. The total construction project duration was approximately 18 months. The extremely dry winter of 2010 certainly helped the construction effort by minimising the impact of rain days.
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Remedial works at Wellington Dam complete. Photo by Paul Hurst, August 2011
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The aim of the $55M Wellington Dam Remedial Works Project was to strengthen Wellington Dam to make the structure stable under flood loading. Wellington Dam is located on the Collie River in the Darling Scarp upstream of the localities of Eaton, Australind and Bunbury. Wellington Dam is classified as an extreme hazard structure in accordance with the ANCOLD Guidelines due to the population of approximately 30,000 who live in the flood plain downstream.
The existing structure is a 35m high concrete gravity dam that was originally constructed in 1933 and raised in the 1950s to its current height. The 360m long dam crest consists of a 220m long ogee spillway crest flanked by broader "non-overflow" section. The dam impounds 185GL, (the second largest storage in Western Australia), which is primarily used to supply water to the Collie Irrigation District on the coastal plain.
The existing structure is extensively cracked and falls well short of meeting current design standards. The dam wall requires post-tensioning with 43 high-capacity ground anchors to stabilise the structure. The largest anchors will be approximately 70m long consisting of 91 strands each with a 279kN minimum breaking load - the equal-largest capacity ground anchors in Australia.
The design solution prepared by the Wellington Dam Alliance (Leighton, Hydro Tasmania, Structural Systems, AECOM and the Water Corporation) is particularly unique as it incorporates the construction of a permanent reinforced concrete bridge deck over the entire length of the 220m long spillway crest to provide safe working access for the installation and future monitoring of the post-tensioning anchors. The 5.1m wide bridge deck positioned approximately 2m above the spillway crest is supported by 1.2m thick piers that also house the post-tensioning anchor heads keeping them above frequent typical spillway flow levels.
The design flood for the structure results in a peak reservoir elevation of some 6m above the spillway crest corresponding to a peak discharge of around 8,000 cubic metres per second. This enormous flow would swamp the new bridge structure, which is required to wash away downstream to create more efficient hydraulic conditions. To give certainty that the bridge deck would wash downstream under rare floods, the bridge decks were designed to rest on continuous lateral Teflon bearings.
Commissioning of the Teflon bearings was particularly troublesome. The 150mm wide bearings originally did not perform as expected and had to be modified in August to allow the individual bridge deck units to slide at the required lateral load. The bearings were reduced in width to 50mm and silicon grease was applied to gain satisfactory results.
Awards
The unique design and construction methods developed during this project were recognised by a number of industry awards including the WA Engineering Excellence Award for Innovation awarded to the project at a gala dinner held on 17th September 2011. The project success was also recognised by the Alliancing Association of Australia.
2011 ANCOLD Tour of the Kimberley September 2011
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The Tour Group at Moochalabra
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The 15 delegates assembled in Kununurra on Friday evening, September 2 for the ANCOLD 2011 Study Tour to the Ord River Dam and Kimberley. We were extremely fortunate to have John Andrews along with us as he had worked on the construction of two of the dams we were to look at.
The first event was dinner at the pump house restaurant. The restaurant has been developed from the original pump station, which was used to deliver water to the irrigation area until the Ord River Dam was built, and still has the original pumps and motors installed.
The Saturday started with an inspection of the Kununurra Diversion Dam gate refurbishment works. This dam is comprised of 5 different dam types. The 340 m long central spillway, containing 20 radial gates is flanked by concrete gravity sections. The concrete gravity section changes first to an earth/rockfill embankment on rock foundations and then a similar type of embankment on earth foundations. The embankment then transitions to a homogeneous embankment.
The spillway includes 20 steel radial gates that are 15 m wide by 11.3 m high, which can be used to regulate upstream water levels during floods. Each gate weighs 95 tonnes and was constructed using riveted connections.
The dam crest incorporates a two-lane bridge link of the Victoria Highway. The bridge is the only all weather road link across the Ord River, providing access between the Northern Territory and the port of Wyndham. The bridge also supports the hoisting gear for the radial gates and provides access for maintenance and operation.
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| Gate Maintenance in Progress |
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The Inspection Team with Steve Dessent
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The 20 large radial gates constructed from riveted mild-steel have been in service continually for 48 years. Unlike other gated spillway structures, the gates at the Kununurra Diversion Dam are operated to keep the storage full and therefore these gates are continually under load in a moist environment.
The gates must therefore be continually maintained to protect the structures from corrosion. This has generally occurred in a scheduled maintenance program that tackles the refurbishment of 2 gates per year with the long-term view of refurbishing all 20 gates in a 10-year period. The radial gates are inspected for corrosion and other defects annually by Water Corporation engineers and the 2 worst affected gates are nominated for refurbishment.
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Wyndham Crocodile Farm
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The delegates then travelled to Wyndham to the 5 rivers lookout and the Wyndham Crocodile Farm before an excursion to Moochalabra Dam in the afternoon for a site inspection of the dam and the spillway.
Moochalabra Dam is situated on the Moochalabra Creek approximately 17 km South of Wyndham. The dam was constructed between 1971 and 1972 to meet the expanding demand for water in the town of Wyndham. The dam was constructed in two stages due to the uncertainties about the catchment hydrology and rate of growth of Wyndham. The first stage was a rockfill structure (designed such that the water overtops the embankment) with steel mesh protecting the crest and downstream face.
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| The embankment |
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| The spillway |
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The last of the drive ins on the
Wyndham mud flats
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In 1999 the second stage of the dam construction was commenced with the raising of the embankment to 31.5 m AHD and the construction of the separate spillway cut into a saddle in the range of low hills that form the right bank of the reservoir. Construction was completed at the end of 1999 and the dam filled and spilled in early 2000.
As John Andrews was heard to comment, "The new Moochalabra Dam is a big improvement on the original and looks absolutely splendid. I was reminded of the tiny little outlet tunnel; which was excavated by hand by two gold miners!"
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| Ord River Dam |
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| Lake Argyle - 1500 sq kms of inland sea |
On Sunday 4th September the delegates visited the Ord River Dam. The morning started with a bus tour from Kununurra to the Ord River dam and a cruise on Lake Argyle.
As John Andrews reminded us, the Ord River Dam was a nostalgic dam for him having spent three years on the construction. He noted that "the Ord River Dam still looks as good as it did when I left and I had never seen it full; impounding had not long started before I left in 1971". He could make out the main features of the old construction township; even if most has been removed and replaced with caravans and chalets!
Arthur Creek Dam is located about 68 km south west of Kununurra town. The dam was originally constructed in 1971 for Goddard of Australia Pty Ltd. TFS Corporation took control of the dam and the properties at Kingston Rest in 2006/7. Since that time TFS has undertaken significant work on the dam to reduce the risks and hazards that have been identified. This work has included implementation of a surveillance programme on the dam combined with improved management of the embankment, construction of access to the right abutment of the embankment, enlargement of the spillway to improve spillway capacity, investigation of the strength and capacity of the outlet works, together with refurbishment and replacement of the outlet valves.
