Major Findings From the Homebush Bay Remediation Commission

This section of the report contains the Commission’s major findings. Click here to view the full report at the Commissions of Inquiry web site.

Development Proposal

• The Lednez site is highly contaminated by a wide range of highly toxic chemicals.
• The near-shore surface sediments in the northeastern portion of Homebush Bay are highly contaminated by dioxins and presently pose a significant risk of harm to human health and the environment.
• Remediation of both the Lednez site and the near-shore surface sediments in the northeastern position of Homebush Bay would in all probability allow the lifting of the EPA’s significant risk of harm classification for that area of the Bay.
• Remediations of the near-shore surface sediments in the northeastern portion of Homebush Bay is the minimum area of the Bay which should be remediated.
• In the circumstances the do nothing option is not appropriate and would severely limit the planned residential development of the Rhodes Peninsula.

Technology Robustness

• The indirect heated thermal desorption (IHTD) technology is a proven technology for remediating contaminated soils and sediments with varying physical characteristics containing a range of concentrations of numerous chlorinated and other chemicals.
• The IHTD technology has not treated soils and sediments with the same physical characteristics and range of concentrations of numerous chemical contaminants as are contained in the soils and sediments on the Lednez site and in Homebush Bay.
• A rigorous commissioning and proving protocol is required for the IHTD technology before it could be given consent for full scale operation.
• An average minimum removal efficiency for dioxins in soil treated by the IHTD plant should be 98.0 percent.
• Base catalysed decomposition (BCD) technology is a proven technology for a proportion of the liquid condensate generated by the IHTD plant.
• Plasma Arc technology is a proven technology for the proportion of the more highly chlorinated wastes not able to be viably treated by the BCD technology.

Public Health

• The data relating to contaminants on the site and in Homebush Bay is comprehensive and is of an acceptable quality for the purposes of the human health and ecological risk assessments.
• A program to assess the significance of chemicals not well characterised and those highlighted by the site auditors should be implemented in the early stages of remedial works.
• The use of an individual chemical risk criteria of 3.5 x 10-6 is consistent with recognised methodology for health risk assessment.
• The use a combined chemical risk criteria of 1 x 10-5 for all chemicals is consistent with recognised methodology for health risk assessment.
• The health risk assessments for the proposed remediation of the Lednez site and part of the bed of Homebush Bay adopted recognised methodologies.
• The NHMRC recommended average lifetime daily exposure of 70pg TEQ/kg bw/month for dioxins is the appropriate ALDE for health risk assessment purposes in Australia.
• A background dioxin exposure level for the community of 1.4pg TEQ/kg bw/d is a reasonably conservative value for health risk assessment purposes.
• The soil acceptance criteria adopted for the Lednez site would ensure public health is protected over the long-term.
• A restrictive covenant is required for the Lednez site to ensure the more highly contaminated soils placed at depth are not disturbed in the future.
• As the actual concentrations of chemicals in the replaced soils would be below the soil acceptance criteria calculated for the health risk assessment, the actual concentrations should be specified as the soil acceptance criteria.
• The level of remediation proposed for Homebush Bay, provided the fishing ban remains, would ensure the health of the community is protected.
• Provided best practice management is used to control and minimise dust generation as well as the IHTD plant and pre-treatment building stack emissions , the likelihood of public health risk criteria for both cancer and non-cancer effects being exceeded at adjacent residential properties during the remediation activities is minimal.
• Sampling and analysis of the dioxin content of off-site soils before and during remediation activities is required.

Noise Amenity

• Noise levels at existing and future residential locations in proximity to the Lednez site and Homebush Bay remediation activities would significantly exceed daytime noise level amenity criteria.
• Noise levels at existing and future residential locations in proximity to the Lednez site and Homebush Bay remediation activities would generally comply with evening and night-time noise level amenity criteria.
• The upper levels of the nearer proposed residential developments would be exposed to the highest daytime noise levels.
• The Applicant has adopted all reasonable and feasible noise mitigation measures in the design of its remediation proposals.
• Some existing residents in Blaxland Road would accept raised daytime noise levels, generally consistent with the current noise environment.
• Existing residents would generally prefer the remediation of the Lednez site and Homebush Bay to be completed in a shorter period, rather than limiting the earthmoving equipment on the site to reduce noise levels, but substantially lengthening the life of the remediation project.
• The Applicant must consult and co-operate with adjacent landowners to ensure the amenity of future residents is protected to the maximum extent reasonably achievable.

Air Quality

• PM10 particulates have been confirmed as affecting the health of people and increasing concentrations have corresponding increased health effects.
• There are well proven methods to control and minimise dust and odour generation during remediation activities which must be adopted by the Applicant.
• Despite the use of best practice methods the concentration of PM10 dust particulates in the Rhodes locality and especially at closer residential premises could exceed the 24-hour average concentration guideline of 50µg/m3.
• Background dust would contribute 40 to 90 percent of the dust concentration at the times the 24-hour average PM10 guideline of 50µg/m3 is exceeded in the Rhodes locality.
• Cessation of earthmoving activities should occur when the total PM10 particulate concentration is likely to exceed 50µg/m3 at any occupied residence in the locality.
• Air emissions from the IHTD, BCD and Plasma Arc plants are relatively minor but do add to the cumulative impacts.
• Emissions from earthmoving equipment would add to cumulative impacts but have not been taken into account.
• Air emissions from the pre-treatment building have the potential for public health effects and must be monitored as required by the EPA.
• Air quality should be monitored at 4 locations on the site boundary as proposed by the Applicant.
• Air quality in the IHTD stack should be monitored as required by the EPA.
• Odour levels on the site boundaries should be monitored.
• The Applicant must reasonably comply with predictions for point source emissions and ground level concentrations as predicted in the EIS and supplementary documentation to provide the highest level of protection to the community.

Wastewater

• Some of the toxic chemical substances in the soil and groundwater are prohibited from discharge to the sewer under current restrictions.
• Current technology would not provide a viable means for the Applicant to reduce the chemicals of concern to below their limits of detection.
• The quality of any wastewater discharged to Sydney Water’s sewerage system must be such to ensure that the health of maintenance workers is protected and the beneficial use of biosolids is not compromised.
• DIPNR, the EPA and Sydney Water have adopted a co-operative approach to resolving issues associated with the treatment and disposal of wastewater from the site.
• The Applicant should conduct wastewater treatment trials on contaminated groundwater extracted from the Lednez site.
• The Applicant must continue to consult with DIPNR, the EPA and Sydney Water to develop and implement effective and innovative wastewater treatment and management measures.

Ecological

• The water quality in Homebush Bay should be monitored by the Applicant during remediation activities.
• The benthic recovery in the remediated near-shore area of Homebush Bay should be monitored over a period of 10 years by the NSW Maritime Authority.
• The level of dioxin in the tissue of fish taken from Homebush Bay should be monitored following remediation by the NSW Maritime Authority and NSW Fisheries.
• The quality of groundwater flowing to Homebush Bay from the Lednez site should be monitored following remediation.
• The reconstructed sea wall should be of a biota-friendly design.
• Remediation of a larger area of Homebush Bay would have additional benefits by further reducing chemical contaminant concentrations and would result in lower dioxin levels in the tissue of fish taken from Homebush Bay.
• Remediation of the 2 remaining contaminated “hotspots” in Homebush Bay could pose significant environmental issues which would need to be assessed prior to further consideration of additional remediation in the Bay.

Co-ordination of Environmental Management

• The Applicant must take the lead role in co-ordinating environmental management in the SREP 29 area.
• The Applicant should develop and implement a developer co-operation action plan in consultation with other developers in the SREP 29 area.
• DIPNR/EPA should fund a full-time environmental officer to monitor the environmental aspects of all development within the SREP29 area.
• DIPNR should establish and chair a Rhodes Peninsula Environmental Reference Group to overview remediation and development in the SREP 29 area.

Community Consultation

• The Applicant should fund a community liaison group for the life of the proposal.
• The Applicant should fund independent technical advice for the community for the life of the proposal.
• Operational and monitoring information should be made readily available to the community by the Applicant, including through an internet site.
• An all hours complaint registration procedure must be implemented by the Applicant.
• The community, through the community liaison group, must be given the opportunity to comment on environmental management plans prior to approval of the plans.

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