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LNAPL Extraction Trial Update

LNAPL Extraction Trial Update. Transpacific Industries Group Ltd Tullamarine Closed Landfill. Tonight’s Presentation. Scope of Work. LNAPL recovery system design. Extraction trial methodology. LNAPL Leachate Well Locations Approximate Former Quarry Extent. Trial Objectives.

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LNAPL Extraction Trial Update

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  1. LNAPL Extraction Trial Update Transpacific Industries Group Ltd Tullamarine Closed Landfill

  2. Tonight’s Presentation • Scope of Work. • LNAPL recovery system design. • Extraction trial methodology.

  3. LNAPL Leachate Well Locations Approximate Former Quarry Extent

  4. Trial Objectives The overall objectives of the extraction trial were to: • Identify the most appropriate extraction option for LNAPL recovery; • Derive design parameters; • Improve the prediction and understanding of the potential LNAPL yield; • Projected system implementation timelines and likely efficiency, if feasible.

  5. Baildown Test Objectives • Baildown tests are to better understand the LNAPL behaviour: • How in well LNAPL thickness varies and how it recovers after pumping. • LNAPL Transmissivity (T) - a key metric to assess recoverability. • measure of how much liquid can be transmitted • “potential seepage rate (per unit area)” • computed by measuring rate of LNAPL seepage to well after pumping.

  6. Baildown Test Objectives • T metric is used in US, Europe as well as Australia. • In addition to T, other key metrics include: • Ability to pump LNAPL from the waste • comparison of initial in-well volume and volume pumped. • Ability to sustain LNAPL pumping rates.

  7. Baildown Tests • On all leachate extraction wells. • Well selection determined by internationally accepted guidance (ASTM E2856 – 11, 2012. Standard Guide of Estimation of LNAPL Transmissivity). • Initial LNAPL thickness (>30cm) • Well integrity testing using dummy pumps

  8. Baildown Tests • Involves removal of at least 80% of the initial in-well LNAPL thickness utilising a pump. • Monitoring of fluid levels, after pumping. • The rate the LNAPL seeps back allows T to be computed. • Results of the baildowntests determine longer term extraction trial feasibility at each location.

  9. Stage 1 Baildown Testing Enclosed Well Head Assembly Sealed Area Vapour Flared Tank (1 m3) Cap GACs 2x Leachate Well Leachate Well Perforations LNAPL thicker in well LNAPL Leachate Pump (intake positioned in LNAPL)

  10. Outcomes • Baildown tests: 15thMay through to 16th July 2014. • Tests completed on all wells that met international guidance standards (13 of the 14 wells). • 1 well not tested (L6) - insufficient LNAPL present to undertake trials (<30 cm). • Tests completed without incident - no vapour or liquid losses. • LNAPL safely transported and destroyed by waste receiver.

  11. Outcomes • Best yielding well (L1) showed a very slow recovery rate (>1 month). • However, it was retested to ensure all LNAPL was removed. • The extra test reconfirmed the very low T and very slow recovery rate.

  12. T metric – 0.074 m2/day

  13. Trial Results

  14. Conclusion • T metric (potential seepage rate) not met at any location. • Extraction from waste limited to 8 of 13 wells tested indicating very low well capture radius. • LNAPL from remaining wells from well storage only. • Of the 8 wells, only L1 yielded appreciable volumes (>50L). • Pumping at best yielding well (L1) sustained for only 398 minutes over 2 events. • Repeat testing of L1 confirmed low T and very low recovery rate. • Very slow LNAPL recovery to wells (typically > 1 month). • On the basis that no metric was met, progression to longer term trials is not practical or achievable.

  15. Transpacific discussion points • Trial Report together with Independent Review Panel findings to be made available for review and comment as part of consultation period. • Stakeholder Consultation period of 6 weeks to commence once above reports are made available. • Transpacific to continue to progress requirements as set out in the PAN and provide an update at the November Community Meeting.

  16. Questions?

  17. Back up slides

  18. In-well LNAPL thickness fluctuations

  19. LNAPL Exaggeration Mechanisms

  20. Transmissivity • LNAPL Transmissivity (T): • measure of ability of formation to transmit LNAPL. • function of fluid, LNAPL saturation/mass and formation. • easy to measure. • indicates potential mobility. • Different to transmissivity in traditional groundwater sense • Saturated groundwater conditions • LNAPL presence typically sporadic and not continuous

  21. In-well LNAPL thickness does not provide an indication of recoverability? • In-well thickness: function of the hydrostatic conditions under which the LNAPL it exists. • Water columns in wells are not used indicate potential groundwater yields and equally not appropriate for LNAPL. • Data below from a confidential remediation site in Melbourne

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