Page 5377 - Week 12 - Thursday, 28 October 2010
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The design brief required that water-holding concrete structures be constructed as to satisfy the requirements of AS3735, and that the surface finish should comply with class 2 of AS3610.
(b) I am advised that no estimate was provided at any stage by the Thames Water (Australia) /John Holland (TWJH) Joint Venture for the application of a protective coating. The joint venture contractors specifically excluded application of a coating when submitting their tender.
5. I am advised that on 21 July 2004 ActewAGL advised the contractor that it did not require the application of a protective coating.
6. I am advised by ACTEW that the ActewAGL Project Manager gave the authorisation to remove the requirement based on advice from the Design Manager (SKM) and on inquiries which established that Sydney Water had not applied a coating to similar concrete structures. A Sydney Water representative was engaged by ActewAGL as an advisor on treatment process matters.
7. I am advised that the quality of water was taken into account at the time of design. At the time, the objective was to make Bendora Dam water suitable for supply to the city. It was assessed that this would be sufficient and so only the water quality from this dam was considered. However, as the supply capacity continued to deteriorate because of the prolonged drought, it later became apparent that water from other sources in the Cotter catchment might need to be treated for supply. In 2006, significant work was done to the Plant to enable it to treat water from the Cotter Dam and Murrumbidgee River. This was required because water from these sources was of poorer quality than Bendora Dam water and outside the original design raw water quality parameters.
8. It is not clear what is meant by “experience at the Googong water treatment plant taken into consideration in the decision making”. If it is to do with concrete corrosion, yes it was. There is very little epoxy coating of concrete structures in the new section of the plant and none in the old section of the plant.
9. (a) ACTEW has advised that the agreed project scope did not include coating of the concrete tanks as this work was excluded from the tender. During the negotiations that took place pre-tender, it was agreed that during the design phase, the Joint Venture would either allow for coating of the concrete structures or convince ActewAGL that coating was not required. ActewAGL subsequently accepted that coating would not be required. As a result there was no budget provided.
(b) ACTEW has advised me that since the coating of concrete tanks was not in the agreed scope there was no time impact recognised in the program for this work.
(c) I am advised by ACTEW that the agreed scope did not contain the coating of concrete tanks. Hence there was no connection with cost, time etc.
10. (a) and (b) I am advised by ACTEW that the under filter area is routinely inspected as part of an annual mechanical inspection regime. However that is not a targeted inspection of the concrete. In 2005 ActewAGL undertook hardness testing on the concrete which indicated that no repair was required at that time, however that strength of the top layer of concrete was lower than expected given the age of the facility and it was decided that a follow up examination should be scheduled before
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