Welcome to the final eNews for 2009 and the first for the new ANCOLD Executive elected at the AGM in Adelaide. It is a great honour to be elected Chairman of ANCOLD and I look forward to serving the Members and Associates throughout my term. I take over from David Stewart whose outstanding leadership has resulted in the success of ANCOLD over the past three years and has provided a sound foundation for the new Executive.  Steven Fox from WA joins Ian Landon-Jones, David Stewart and I on the Executive. Angus Swindon also joins us as Secretary and David Brett as Treasurer.  The transition to the new Executive has been smooth and should be complete by Christmas.
 
Past Chairman Brian Shannon leaves the Executive after twelve years service. Brian previously also held the role as Treasurer. Brian's leadership has greatly contributed to the current success of ANCOLD and I will continue to seek his wise advice. Thank you Brian, I look forward to catching up with you at future ANCOLD events.
 
Grateful thanks are also extended to past Secretary Andrew Reynolds and Treasurer Stephen Newman for their tireless management of ANCOLD affairs. These positions are a major personal commitment and fundamental to the efficient running of ANCOLD business.   
 
The ANCOLD conference in Adelaide was a great success thanks to the skillful preparation and management by Andy Parsons and his organising committee and Andrea Goodwin, Paula Leishman and their team. Over three hundred delegates attended and the feedback I have received has been overwhelmingly positive. Andy and his organising committee have been invited to take their partners to a celebratory dinner as an expression of thanks from ANCOLD.
 
The workshop has become a feature of the annual conference, contributing to discussion on current practice and the requirement for guideline review. The 'Current Practice in Seismic Dam Engineering' workshop in Adelaide was well attended and set the scene for a review of the earthquake guidelines. Thanks go to Steve O'Brien and his team for pulling together the technical content.
 
ANCOLD's thanks are also extended to the conference sponsors and exhibitors for their contribution. The increase in sponsorship and the number of exhibitors are providing delegates with valuable information on the range of products and services available to the industry. Their financial support underpins the conference and many other ANCOLD activities and services to members and associates. Their ongoing support is greatly appreciated with the 2010 conference in Hobart already well subscribed.
 
The Executive will be meeting in February 2010 to review the strategic plan and develop activities to deliver that plan. Details will be reported in the next eNews.
 
Angus Swindon is in the final stages of organising the USBR Safety Evaluation of Existing Dams (SEED) course to be conducted in March. Expressions of interest for attendance have been strong. It is a grand opportunity for Australians to attend this renowned dam safety training course, normally only available in the USA.   The dates and locations are available in this eNews and registration information will be available in the new year.
 
I wish to welcome Michelle Miller of Leishman Associates who will be assisting Angus in the ANCOLD Secretariat. Michelle is likely to be your first point of contact for general ANCOLD correspondence.
 
Finally I thank all members and associates for their support of ANCOLD and wish you and your families a safe, enjoyable, and peaceful Christmas period. I also hope for some rain in the New Year to quench the thirst of our parched land.
 
Neil Blaikie
Chairman

 

Newly appointed Executive committee for ANCOLD. Pictured from left to right; Ian Landon-Jones (Senior Vice-Chairman), David Brett (Treasurer), Neil Blaikie (Chairman), Steven Fox (Junior Vice-Chairman), Angus Swindon (Secretary) and David Stewart (Past Chairman). 

 

 

Applications should be forwarded to: 

ANCOLD Secretariat

C/- Leishman Associates

113 Harrington Street

Hobart, TAS, 7000

email: ancold@leishman-associates.com.au

 

Applications close 29 January 2010

Stage 2 of the upgrade to Stirling Dam comprising the dam safety remedial works has been completed by Macmahon.  Stirling Dam is a 53m high, extreme hazard dam located approximately 130km south of Perth.  The dam supplies in excess of 10% of the Perth metropolitan potable water usage.  The remedial works included widening of the spillway to pass the PMP-DF of 1,500m3/s (outflow), excavation of the downstream rockfill shell, construction of filters and rockfill weighting over the downstream face. 

 

This involved excavation of 120,000m3 of overburden and 180,000m3 of rock from the spillway chute, excavation of 140,000m3 of rockfill and gravel off the downstream face of the embankment, and placement of 45,000m3 of filters, 95,000m3 of rockfill and 30,000m3 of earthfill. 

 

The design, scheduling and construction management included significant issues with water management which have been documented in the proceedings of the 2009 ANCOLD conference.  The storage filled to within 2.5m of full by early November 2009, storing 46.5GL.

The end of winter has seen a recommencement of works at Drakesbrook Dam near Waroona, 80km to the southwest of Perth. The first season's work saw C.E.C.K construct a new high level outlet on the left abutment, sleeve the original low level outlet with PE pipe and construct a valve pit. The second season sees the Water Corporation's Engineering and Construction Services group take over the mantle on site and they aim to construct a new spillway and install full height embankment filters.
 
Work to date has seen the demolition of the old concrete chute (that could best be described as meandering in alignment), the opening of a borrow area within the reservoir basin and the commencement of blasting for the construction of the new spillway. Progress on the project has been good since commencing on site and is on track to be completed before the onset of winter in 2010.

 

GHD is undertaking the design of the pipeline to connect Logue Brook Dam to the Harvey Water Piped Irrigation System.  This is the last phase of the development of the piped irrigation system in the Harvey and Waroona irrigation districts. 

 

The works consist of about 5.25km of DN 800 PE pipeline and a connection of the pipeline to the dam outlet works.  Logue Brook Dam was completed in 1963 and is one of the sources of water supply for the Harvey Irrigation Scheme.  

 

The existing outlet works include a wet inlet tower with a bulkhead gate and a valve house where a clam shell valve has been used to regulate flows down the river.  The new connection will enable the irrigation releases to be fed directly into the pipe network. The works at the dam consist of an upgrade of the outlet valve house to allow the connection to the pipeline and an upgrade of facilities in the inlet tower to enable safe closure of the system for the link in of the new pipe to the outlet works. 

 

However a diving inspection on the inlet tower, undertaken in October 2009, showed that the vent pipe is completely corroded and the bypass valve needs replacing.  Repairs to these items will have to be undertaken before the outlet works can be shut off and the system isolated.  However as there is no access bridge to the tower, access will also have to be upgraded for the duration of the works.

 

 

 

 

 

 

 

 

 

 

 

 

 

At the valve house the existing sluice valve, pipes and fitting will be removed and replaced with a DN900 butterfly valve with the capacity to close into flow under emergency conditions.  The other two valves are essentially all guard valves and normal operating characteristics will be adequate. The existing clam shell valve and actuator will be retained. A DN250 environmental outlet will be installed including DN250 butterfly valve, DN250 magflow meter and DN250 butterfly valve.   The civil works comprise a new webforge decking platform and a precast concrete roof, replacement of existing concrete staircase and handrails.

The first DN1800 fixed cone dispersion valve at the Ord River Dam was removed in late October 2009 to be refurbished at ACRON'S workshop in Melbourne. The refurbishment of the three regulating valves is aimed at restoring the valves to near new condition and hence improve their performance.  The valves will be refurbished one at a time to maintain the outlet works in operation.

An access platform was built downstream of the pit opening and above waters infested with crocs. The valve was horizontally moved out of the pit over a rail and then lifted with the use of a spreader beam.

 

 

 

 

 

 

 

 

 

 

On arrival at the workshop where the valves are being refurbished, the valve will be dismantled, blast cleaned and undergo non destructive testing.  An inspection will be carried out to redefine the refurbishment scope of works. The refurbishment work is expected to take 2 months.

 
Dam Safety (Croc Attack) Issues in the Kimberley

 

The Water Corporation's dam safety inspection team have been aware of the potential threat from salt water crocodiles during the annual inspections in the Kimberley. 

 

The safety procedures have now developed to the stage where the inspection team is backed up by a croc spotter and a shooter, Luke the Crocodile Control Officer from the Department of Environment and Conservation (see photograph left). 

 

 

The September 2009 inspection started with a safety briefing that had identified a 3.5 m "salty" doing laps downstream of the dam, but otherwise everything was normal. However by the time the team had reached gate 4 (out of 20) the alarm was raised, the croc was on an attack mission.

Fortunately the whole team got the message in time and were able to retreat a safe distance before the croc beat a retreat. Needless to say the photographs were a bit of a mess and this was all that could be pulled together. 

 

 

 

 

Moochalabra Dam is a 30 m high earth core rockfill dam that is the sole source of supply to the town of Wyndham in the far north of WA.  The catchment area is 59 km2. 

 

The dam was originally constructed in 1971 as a mesh reinforced over topped rockfill dam that was meant to have a life of 10 years before the mesh anchors corroded out. 

 

The dam was finally reconstructed and raised in 1999 and now incorporates a 105 m wide unlined spillway cut through sandstones of the Pentecost Group of rocks. The peak flow through the spillway was in 2006 when the spillway flowed 2.7 m deep with a flood estimated at slightly less than 600 m3/sec. 

 

Although the spillway has performed well, the flows have been somewhat higher than expected, based on comparisons with the original stream gauging station that operated for some years downstream of the original dam.  Part of the cause has been attributed to the rating curve being unreliable at the higher flow rates where physical flow measurement was not possible.  However in wet years we are still estimating flows with runoff coefficients of 200%, which is good work if it is true.  While this is attributed at least in part to an orographic effect in the catchment, there are some uncertainties about the rating curve being used for the spillway.

In an effort to upgrade the rating curve for the spillway, the Department of Water has constructed a traveller way over the spillway to facilitate flow metering.  Access to the site during the wet is restricted, particularly during a flood event and helicopter access has been arranged.  The flow metering will utilise Doppler velocity and depth measurement.