Yes, chlorine could disrupt the unique environment of Westernport, and we have to take this risk very seriously.
During the open loop process the ship’s system, like a filtration system in a salt water swimming pool, produces a small amount of chlorine, being approximately 0.1 of a milligram a litre at the release point, from the seawater to keep the system clean.
So far, EES referral assessments conducted by environmental scientists found that when the water returns to Western Port it will break down to an undetectable level within 20 seconds. In other words, the level of chlorine in the water that’s returned to the port would be significantly less than that allowed in our drinking water.
The report concluded ‘The process of initial dilution from the six-port discharge port/s will reduce the concentration of free chlorine residual from 0.1 mg Cl2/L at the outlet to 0.005 Cl2/L at the seabed. Further mixing with tidal currents within 200 m of the discharge point will reduce the chlorine concentration in seawater at ambient temperature of 12°C is to 0.003 Cl2/L within 200 m downstream of the discharge point, while in warmer seawater (16°C to 18°C) the chlorine concentration is estimated to reduce to 0.001 mg Cl2/L within the same distance. ·
Discharge of the seawater via a six-port discharge, in accordance with AGL’s preferred design, is expected to reach environmentally safe concentrations within an area extending approximately 200 m downstream of the discharge (north during rising tide and south during lowering tide) and 60 m east and west, based on the existing model outputs and regulatory guidance values for chlorine toxicity.’
The full report can be found here.
The issue of chlorine is subject to further investigation as part of the EES.