Presentation on theme: "Tullamarine Rehabilitated Landfill > 26 November 2014."— Presentation transcript:
Tullamarine Rehabilitated Landfill > 26 November 2014
Post Closure Management Plan Progress 2 Mounds 1 & 2 Cap Construction Drainage connection approved by Tender & Works Melb Water & SEWPaC Works Commence 2014/15. Liquid Product (LNAPL) Extraction (Feasibility trial commenced 2014) Landfill Gas Management (Landfill Gas Sampling and Perimeter Monitoring completed 2013 & final flare design & install 2014) Groundwater & Surfacewater Management (Risk Assessments Completed in 2004 & 2007 and Indicated Low Risks. A technical review was completed in 2011/12 of over 100 boreholes and along creek continues to confirm the same). Cap Audit Completed Groundwater Management Protocol (Approved by SRW) Cap Water Gas Oil Green Arrows = Water Act Vic, 1989 Deliverables Grey Arrows = Environmental Protection Act Vic, 1970, Deliverables Next Review 2014/15
LNAPL Trial Remaining Tasks >Consultation (workshop & questions tonight) >Questions are able to be put to EHS (and the IRP) until end of December (note now end of February 2015 as discussed in meeting) >Draft report issued to community mid to late January >Special meeting with EHS & A. Lane mid February >Practicability Assessment Report (Issued March 2015) >The Practicability Assessment Report will include consultation process and responses to questions from community.
Reminder - What does the EHS report mean? >The trial has shown LNAPL extraction is not feasible because the volumes and recovery rates are so low >At current levels of recovery extraction will take in the order of 1,000 years >The LNAPL is effectively immobile >Other technologies were ruled out during planning / design because of risks to cap integrity and/or risk of mobilising contamination
>The EHS information is indicating further field trials are not justified >However it is only fair that the community and stakeholders have time to consider the detail in the technical information Reminder - What was proposed?
>Biodegradation is occurring in the landfill >Microbial bugs consume the easier less viscous (thinner more mobile) compounds first leaving thicker and less mobile compounds until last >Biodegradation is happening because : >The landfill temperature is declining >The landfill gas production is also occurring (and declining) Why is it so difficult to extract?
>It won’t move >It will eventually turn into an inert material that looks something like black carbon >It will undergo anaerobic biodegradation and this will be explored in the EHS Practicability Assessment report (the process is called anaerobic reductive degradation and includes dechlorination, ie, chlorine in PCB is removed) >Transpacific will continue to monitor What will happen to the LNAPL?
Next Steps >Opportunity to ask questions and seek clarification. >Reports were made available on the community web site. >Consultation continues beyond the original 6 to 8 weeks envisaged from the 15th Sept (when the community can ask questions / comment on the reports). >Opportunity to ask questions at tonight’s meeting.
>Transpacific to make EHS and the Independent Review Panel available for questioning (tonight). >Transpacific will use tonight’s meeting to assist the community formulate questions to our experts. >We will take further questions until end of December (now end of February) and EHS can respond in detail in the Practicability Assessment report (March 2015). >Site visit to the Landfill (two members attended) Next Steps ctd…
Hydraulic Containment Impermeable Barrier Excavation and Disposal In-Situ Vitrification In-Situ Cement Solidification Fluids Extraction Active Skimming Belt Skimming Steam Injection Resistive Heating Solvent Extraction Surfactant Flushing Air Drive / Water Flood Vacuum Extraction Vacuum Enhanced Hydraulic Recovery In-Situ Chemical Oxidation (ISCO) Bioremediation Reminder of The Technology Screen
Health, safety and environmental impacts/ risks, including: Generation of vapour / dust emissions Penetrations through and/ or damage to the land fill cap Permanent changes in LNAPL characteristics LNAPL mobilisation Landfill fires LNAPL storage and handling Technology Considerations
>Cap (Installed) >Hydraulic Control (Assessments will be completed March 2015 – SRA, HA and LNAPL Trial) >Gas Collection and Emissions Flaring (Installed and currently undergoing confirmatory assessment). >GW & LFG Monitoring (Monitoring network installed and monitoring is ongoing) >Natural Attenuation [attenuation assessment completed for the Technical Review (TRAR), currently being reviewed by Auditor]. Multiple Technologies Employed at Tullamarine Landfill
Technology Considerations >The Natural Attenuation assessment indicates dissolution from LNAPL (until it naturally depletes) will be managed effectively via Monitored Natural Attenuation. More to report on this at the next meeting. >The landfill gas collection system vacuum can be considered as an active management measure for collecting vapour emissions and assisting with stripping volatile components of the LNAPL which are typically the most soluble as well.
After R. Charbeneau, 2012 Mobility Over Time Time (Years) Tn (m 2 /d) Data from US
After T. Sale, 2012 Recovery Rate Over Time ML First liquid disposal about 1973 & last disposal in 1987 (about 40 years since first disposal & 27 years since last disposal. Time (Years) Extraction Only Bio degradation Only Extraction + Bio degradation Data from US
Tullamarine Landfill >The landfill is in the period between ability to practically extract and LNAPL being absorbed to clay particles >Note that intervention has potential to cause greater harm
Biodegradation Processes - Landfill
LNAPL Leachate Waste Cap Gas Collection Layer Flare Biological Activity Biodegradation Processes - Landfill Biological Activity
50 mg/kg NEPM Soil Guideline for Industrials Sites Location PCB Concentration (mg/kg) L115 L421 L529 Well 631 L738 L1360 L14102 L3102 L8106 L12123 L1188 L2210 Well L9215
Monitored Natural Attenuation
Natural Attenuation and Biodegradation >Biodegradation via anaerobic reductive dechlorination and volatilisation enhanced with the landfill gas collection system. These two process are likely the key ones for the ultimate degradation of the LNAPL at the site. >LNAPL at Tullamarine is more complex than “standard petroleum site”. Biodegradation is also considered important for a wide range of contaminated sites and as such has much wider applicability than just standard petroleum sites.
Biodegradation (US EPA Fact Sheet)
>“Fortunately, petroleum hydrocarbons appear to degrade to less harmful products in almost all cases.” USEPA Remedial Technology Options Fact Sheet ‘Monitored Natural Attenuation of Petroleum Hydrocarbons’ Biodegradation (US EPA Fact Sheet)
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