Agendas | Minutes

Homebush Bay Dioxin Remediation Project
Community Liaison Group
10th Meeting
Minutes of Meeting 26/03/03 

( Answers to Questions submitted in advance )

( Answers to Questions asked at the meeting )

( Presentation at Meeting )

When: Wednesday 26 March - 2003 - 5.30 to 7.30 pm
Where: Rhodes Community Centre
Attendees: John Kent, Independent Chairman
Dr Kate Hughes - Independent Technical Reference
John Pym - Independent Technical Reference
Con Lambous - Sydney Olympic Park Authority
John Pike - Rhodes Peninsula Group
Paul Hanly - Rhodes Peninsula Group
Carol Kendall - Rhodes Resident's Group
Jenny Nicholls - Rhodes Resident's Group
Dietrich Willing - Friends of the Earth
Peter Down - Greenpeace
Sundar Mahtani - King Street Area Residents Group
Councillor Pauline Tyrrell - Canada Bay City Council
Bill Ryall - Site Auditor (commissioned by Environment Protection Authority)
Rui Henriques - Thiess Services
Doug Moss - Thiess Services
Fiona Court - Parsons Brinckerhoff
Malcolm Dale - Parsons Brinckerhoff
Diane Sismey - Parsons Brinckerhoff
Mersina Soulos
Apologies: Don White - Nature Conservation Council
Louise Hayes - Meadowbank West Ryde Progress Association
Laurie Gordon

Chairman's Welcome
1. The meeting commenced with the discussion of the previous meeting record.
The previous meeting record was accepted.

2. Matters Arising
There were no matters arising.

3. EIS Exhibition and Future of These Meetings
Diane Sismey gave an update on the current status of the EIS exhibition and the Commission of Inquiry, and how to provide submissions on the EIS to Planning NSW. Inquiries as to these details should be directed to Diane Sismey at PB.
Discussion as to the future of the CLG indicated that most of the group was interested in continuing involvement once remediation began. It was also suggested that the group be readvertised to freshen up membership. Thiess agreed that new faces may need a project history/group orientation package. New members would also need to realise that it is a long-term commitment, not a one off meeting commitment. Group Terms of Reference need to be explained.

4. Presentation by Thiess
Doug Moss reviewed the risk assessment process for the site and explained the criteria used. Questions raised during the presentation are outlined below.

Issues and Questions
4.1 Depth of Cleanup and Services Impacts
Contaminated soil/material at a large depth presents a reduced risk to the project. As such Thiess will remediate to a depth required to provide minimal risk. Some material may remain inside rock fissures or seams at further depth.

Is there a possibility of bay recontamination from site groundwater seepage?
The EIS documents the results of groundwater modelling that show potential groundwater flowpaths. Impacts on the bay are assessed.

What about vertical recontamination through gases moving upwards through rock structures?
The risk assessment process accounts for these potential re-contamination flow paths and must be very low to leave material in-situ.

What about the potential for corrosion of underground water pipes?
Only the sewer pipes are lower than the present containment cell, all other utilities are located in remediated soils. The detailed redesign of the sewerage has not yet been worked out. This will need to be looked at during the remediation activities. The site will be designed and corridors designated for utilities and services. The earthworks and soil replacement strategies undertaken by Thiess will accommodate this.

At Newington they use PVC piping to collect water and send it to the liquid waste plant, will this be the case at Rhodes?
The soil left at the Lednez site will have been treated and therefore is not unacceptably contaminated. This is completely different to the situation at Newington, which is contaminated waste.
Note: Bill Ryall noted that the clean up criteria for all the earthworks is very conservative and therefore soil condition throughout the site is expected to be of a sufficiently high quality.

Will there be further risk assessment following the site clean-up?
Yes, this will be addressed later in the presentation.

4.2 Clean-up Criteria per Kilogram Body Weight (refer to Figure below)
Risk Assessment for the Lednez Site

 

Has the criteria of 2.3 mg per kilogram body weight per day been set in concrete? Is it possible for it to be lowered?
The World Health Organisation (WHO) has set a safe limit of between one and four mg per kilogram body weight for dioxin exposure from soils averaged over a 70 year time period (that is, a lifetime). The Australian Health Council has come up with a more conservative criteria of 2.3 mg per kilogram body weight. This is the criteria Thiess has been directed to use by the Environment Protection Authority. Thiess has been additionally conservative in their calculations by using the risk assessment case of a child of one to six years (lower body weight), regularly consuming soil on-site.
Note: John Kent noted that the background level (that is, from breathing/living) is 1.4 mg per kilogram body weight per day. This was documented in a New Zealand study. Future exposure on the Lednez site is actually estimated as around 1.6 mg per kilogram body weight.

Is the difference, that is, the 0.19 mg per kilogram body weight per day exposure criteria calculated in the risk assessment based on on-site contact with the soil?
Yes, it is based on the risk assessment criteria of a 70 year life span in contact with the cleaned soil on site. It is noted that for the Homebush Bay site, topsoil will be imported for landscaping purposes, further reducing risk.

Do you think studies into background dioxin exposure levels will be undertaken in Australia, similar to the New Zealand study referred to by John Kent?
Bill Ryall indicated he thought so, but it is still a long time until results from such studies would be available.

How can you be certain that your treatment levels are sufficient if the background level is actually higher than 1.4 mg per kilogram body weight? That is, if background levels go up, then this will push the total exposure closer to the criteria or maybe exceed the criteria? 
The clean-up criteria set by the risk assessment are so low (0.19 mg per kilogram body weight) that the soil could be considered 'cleaner' than most natural soils found around Sydney. There is not much that can be done if background levels increase or exceed the goals.

What is the measurement limit for dioxins?
The limit of detection is 0.05 parts per billion in soils.

How do calculations include the background levels?
We assume background levels to be 1.4 mg per kilogram body weight per day. The risk assessment process then back engineers or back calculates to ensure that total exposure is below the criteria.

4.3 Plan of the Site to be Developed Shown
How high will the sea wall be?
It will be the same as it is now - as prescribed by PlanningNSW in the Development Control Plan (this document publicly available).

Where there is going to be a park on the site, will Thiess remediate to deeper levels?
No. On the site near the foreshore we have a lot of soft material which is difficult to reuse for building foundations as it is not as stable. That softer material will be put beneath roadways and the rockier material will be placed below residential buildings. There is no difference in the contamination criteria used around the site.

Is the amount of regrade shown in the presentation an accurate representation of the amount to be used under buildings?
The amount shown in the EIS is the most conservative possible scenario. It is anticipated that buildings near the site foreshore will be supported on piles, while the buildings at the back of the site will be piled on the downslope side only.
Bill Ryall noted that all open space areas will be covered in a further layer of imported top soil. Doug Moss noted that the import and laying of topsoil is part of Multiplex's responsibility. Bill noted that he will give sign-off on Thiess site clean-up subject to the risk assessment criteria being met. This criteria will include conditions with which the developers will have to comply before the site is signed-off.

4.4 Clean Up Criteria
Clean Up Criteria

Are you using the same clean-up criteria over the entire site or is the 1.6 mg per kilogram body weight per day exposure only applicable to areas of open space?
Unable to confirm the exact criteria for the entire site. Need to check with Egis (risk assessment consultants).

When you treat the soil, you won't find any dioxin in it?
We are expecting a concentration of about 50 parts per trillion after treatment. The concentrations of tetrachlorobenzene drive the treatment process in regards to criteria, as this contaminant is one of the most difficult to remove.

Why is the criteria for concentration of tetrachlorobenzene so much higher?
You will need to look in the risk assessment for justification of the numbers. The risk assessment process was undertaken following protocols established by the Environment Protection Authority.

What has been decided regarding the possible options for BCD post-treatment?
There are still the on-site and off-site treatment options. At this point in time, it appears as though off-site treatment will not be looked at favourably.

What happens if you find contamination in the site bedrock?
If that occurs it will be put to the site auditor to ensure that the criteria for making the site safe can be met. After the criteria have been met and risks are considered low enough, the material would be left in situ.
It was noted that pre-foundation construction "pest treatment" is likely to raise contaminant levels again - probably to a point that exceeds criteria. Thiess noted that they will achieve auditor sign-off and that Multiplex need to deal with that issue.

5. Question and Answer time
Doug Moss noted questions sent to him by John Toohey and addressed them as follows. Questions submitted by Paul Hanley were answered on a handout.

Has diesel fuel use on-site been taken into account in the air quality studies and risk assessment?
No. It has not. Though, interestingly, it was calculated by John Hunt that the emissions from the exhaust stack of the ITD plant would be about 2 ng per hour while a diesel truck emits about 10.3 ng per hour.

The wind roses in the EIS are Environment Protection Authority data from Lidcombe. Would conditions actually be worse at Meadowbank?
Referring to the air report by Kerry Holmes in Appendix D - to all intents and purposes the results for both sites can be considered the same.

Can the risk assessment be considered invalid if it doesn't take into account all aspects of the remediation (for example, truck emissions)?
The most important health aspect of this project is the emissions from contaminated materials. Emissions from trucks etc. have not been considered in the same assessment and would occur even if the site was not contaminated.

Will the ITD plant be gas powered?
Yes.

What will happen with data on emissions and site work during the remediation?
Thiess anticipates that remediation progress will be disseminated in a regular way to the public via this CLG.

CLG may not be a regular enough forum, what then?
We could put information on a web page, or disseminate via other mechanisms.

Was this committed to in the EIS?
No, however this could be requested in a submission on the EIS to PlanningNSW.