Information surrounding the sewage solution to date is confusing. I am not sure if there is a quantity surveying firm engaged on this project, but the information I have read leads me to believe the design engineers are providing cost information. The selection of a site or sites should be an easy process based upon construction cost and the simplicity of the design.
The sewage treatment in Halifax should remove any concerns regarding smell, noise and no smoke stacks and allow the facilities to be built in any part of Victoria, especially if the design is pleasing to the eye.
When the project reaches the tendering stage, it is important that the contract documents are accurate and concise and leave contractors bidding the project with a sense of confidence in submitting their bids. Any ambiguities in those documents will be reflected in their bid amounts.
Some other thoughts: In the event of an earthquake, multiple sites might be the better option. Plants of the same capacity can use common equipment and design between sites. Don’t go cheap, there is no cheap solution to do it right. Look at the life cycle cost for balance for consistency across design and equipment. Have a sinking fund so that we are not faced with this problem in the future.
Based upon the current estimates what is the percentage contingency allowance? The costs can only be generic and not site-specific due to the lack of information to form an estimate. Only an order of magnitude estimate can be created at this point in the design which is subject to plus-minus up to 25 per cent.