Gas Import Jetty & Pipeline Discussion

Chlorine discharge

Chlorine discharge

Chlorine discharge

Starter

By what means are you measuring the impact of 145 million litres of biocide discharge per day. Westernport has high tidal movements and I’m wondering if your figures of dispersion of the chlorine are based on data or theory

4 REPLIES 4
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Re: Chlorine discharge

Sparky

Chlorine kills bacteria so therefore it would be damaging to the fragile eco system of the Westernport wetlands surely?

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Re: Chlorine discharge

AGL Employee

Hi @Netpassword,

 

We’d just like to apologise for the delay in addressing your enquiry – we have received a large number of complex and detailed questions that we need to discuss with a few specialists.

 

This is not the way we want to deal with community concerns and we’re working to be more responsive in the future.

 

We’ll respond to your question shortly.

 

Thanks,

Lachlan

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Re: Chlorine discharge

AGL Employee

Hi @sunflower,

 

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.

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Re: Chlorine discharge

AGL Employee

Hi @Netpassword,

 

Let me be clear about the amount, it is not 145 million litres. When operating at full capacity, the Floating Storage and Regassification Unit (FSRU) will actually require 450,000,000 L/day of seawater. It is only anticipated that the facility would run at this maximum for possibly 4-6 days per year, during extreme demand days in winter.

 

The rest of the time it will either be using 300,000,000 L/day (high demand days in winter), 150,000,000 L/Day (low demand days in Spring and Autumn) or not at all – there is currently only one ship scheduled to make a delivery in summer. However, all our assessments must be based on worst case scenario.

 

The technical studies relating to the chlorine discharge are currently underway, however once finalised the EES will be made publicly available and you will be able to make a written submission on the EES during the exhibition period. The information we have received is the opinion of independent experts.

 

While the studies completed to date in the preliminary assessments demonstrate that the impacts to the environment associated with this project will have minimal impact on the environment, an in-depth investigation is being undertaken as part of the Environmental Effects Statement.

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