Mitchell Dam - Part 2

Previously I created a post outlining the main reasons why a dam on the Mitchell River in Gippsland is not the solution to Melbourne's water supply.

The latest information from the BoM outlining the lack of rainfall has reinforced that relying purely on rainfall is not a solution for Melbourne. It would be a case of having one's eggs all in one basket, or in this case, a couple of baskets sitting side by side.

If you consider the water supply an investment, why would you invest in one asset type alone? Sure when that asset is performing (excess rainfall) things are good, your stocks go up (dams fill). But when the stocks underperform (drought), your portfolio looks quite sad.

So diverify the supply, invest in alternatives so that one can be used as an income source when another is underperforming.

I am not fully convinced that the desalination plant is the best option. On the positive side it is a diverse supply, it is not dependent on rainfall for supply. The negatives communicated in the media relate to the huge amount of energy required, the potential impact on the coastline and the capital costs associated with the works.

$3.1b is the listed estimated cost of the project. Compare that to the $1.35b published for the Mitchell project. The cost difference looks huge, when in fact when the dam estimates are updated to current dollars the dam construction cost is over $2b (see my previous post on this matter). Not included in that estimate are a great number of un known costs that would certainly push the dollars up (they never make them go down).

The issue that Melbourne Water will be facing very soon is the growing negative PR that is being generated by various bodies. Almost daily protests are being held in the Wonthaggi area that are visual and well organised. If they are not careful there will soon be a significant backlash generated on emotion rather than fact or science that will overwelm the project.

So, the more important question is - How does Melbourne diversify it's water sources?

The usual suspects include:

reducing demand - Melbournians are pretty good at this but it is not a long term solution; or

demand replacement - use recycled sewage or stormwater runoff to replace some supplies;

The first option there is well known. It has been going since before the Thomson Dam was completed with the "Don't be a Wally with Water" and now the target155 campaign.

The second option is in my mind more interesting and more viable long term.

There has been a reasonable history of water recycling through the farm at Werribee and more recently the Eastern Irrigation Scheme.

Melbourne Water has committed $300m or so to improving the quality of water discharged from the Eastern Treatment Plant (ETP) to Class A which is suitable for a number of things other than drinking or direct contact with humans. This water after being treated will be pumped to Boags Rocks for discharge to Bass Strait.

I find it short sighted that Melbourne Water has not pursued the use of this water as a substitute for potable water in the south east, especially for industry.

There was an ideal opportunity for a pipe to be constructed as a part of the EastLink project to carry water northwards along the Dandenong Creek Valley to service industry, golf courses and basically anyone else who wanted the water.

Another system that is starting to be considered is the use of excess sotrmwater runoff as a re-usable resource. The Essendon Football Club has just completted such a system under the Windy Hill Oval.

Similar systems are incorporated into the MCG and Etihad Stadium. This type of central recycling system could be built into retarding basins and be used to water sports ovals, golf course, school ovals, parks, gardens, or used for suitable industrial processes.

By having a commitment to finding solutions to the problem that are not just based on damming a river of desalination, Melbourne will have a more stable and diverse water supply in the future.