Will the port Phillip bay channel deepening project damage the bay?

Question

http://www.theage.com.au/multimedia/dredge/main.html

Answer 1

Considering the PPB dredging will disturb 40 million cubic metres of sediment including some highly toxic material, to be dumped within the confines of the bay, and remove the hard capping from the rock at the narrow entrance, creating significant erosion which will last for decades, damage is unavoidable. The question is how much?

PPB has unique marine life including a dolphin sub species of just 86 individuals, and is the breeding ground for most of the states snapper fishery. It is a very confined embayment of 1943 sq km with a 3km wide opening, in which some parts take up to 18 months to flush water, a bad environment in which to release buried toxicants like DDT, PCP's, Lead, mercury, and the list goes on. Alan T, your source indicated wind speed, not current. The chart maximum current is 8 knots at the entrance but less than 1/2 knot for most of the bay.

The people of Melbourne swim, eat from, and dispose their sewage to a finely balanced ecosystem. A disruption to the nitrogen recycling capabilities would force 3 million people to change to septic toilet systems, a secondary environmental disaster. The entrance to the bay has THE most colouful sponge communities in the world, many endemic, all filter feeders who may not survive two years of 24/7 dredging.

The project will allow for more and bigger ships, bringing imports like cheap electrical goods, and marine pests which will be greeted by a weakened ecosystem for them to gain foothold, and eventually dominate.

The studies by the dredgers are dodgy at best, with most results manufactured from insufficient data, and some pure spin. The business plan requires taxpayer funding, and includes crushing many bay dependant businesses, with no compensation.

Even the Exxon Valdez would not cause the damage this project probably will, and that was officially a disaster. Victorians will long regret the day they allowed shipping companies to to decide the fate of their most treasured asset.

Answer 2

Dear Alan, you have no idea about port Phillip and the dredging process, The contaminants in the river are so toxic that they were banned from being dumped into the ocean because of toxicity, so they think they will box the contaminants into a bund and seal it.   You know nothing about the many indigenous and local flora and fauna that inhabit this bay and this bay only. You know nothing of the commercial interest that will be severely affected by the turbidity and damage caused by the dredge. You know nothing of the ever increasing information about the harm that shipping exhaust causes to people who live within shipping ports or routs close to civilization. You know nothing of the pollution that the extra ships will cause downstream, i.e more trucks in the city, using more fuel and causing even more air pollution.  We have many alternatives here in Australia, but it is a pissing contest between big business/ Government  and the people of Victoria.

Please keep ill informed comments to yourself and don't comment until you realize the full extent of what may happen.

Dave

Answer 3

Ok let me first start by saying that dredging does have an impact on the environment but it is not as substantial and long term as most believe.

I work on a tug boat on the New York Harbor and have been dealing with dredging for about 7 years.  Before I started working on a boat I worked for a dredge reclamation facility that processed contaminated dredge (normally contaminated with hydrocarbons a form of petroleum or oil)  with Portland cement.  This process caused a chemical reaction when the Portland came in contact with the hydrocarbons causing the hydrocarbons to "burn" off causing a small amount of byproduct of ammonia allowing for the material to then be used as fill material on landfills and for base material for building products because it sets up like dirt.

The dredging process its self disturbs the bottom of the bay but the area is normally small depending on the amount of dredges that are operating at one time and weather/current speed can affect the water from "flushing" out the reasonably small amount of disturbed water due to the disturbance.  I looked at the normal current speed of the bay and I believe that it should be able to flush most of the disturbed sediment suspended in the water out to sea fairly quickly because the current flows at 8 through out the bay to 16 knots at the entrance.

The disturbance isn't a totally bad thing for the environment it stirs up food for bottom feeders and isn't as uncommon as most may think.  Consider how much the bay is disturbed after a 1 in a 100 year storm, this too would turn the Eco system upside down but in a larger scale than that of a long term dredging project.

I hope this helped answer your question and just to add I am also currently a Penn State University student studying Hydrology focusing on dredging.