Transcript FirstWord Second Third

Landfills – the next mining boom?
David Gamble
GHD National Service Line Leader, Waste Management
Overview of Presentation
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Reasons for mining waste
Issues to be considered
Logistics and other challenges
Overseas examples
Future overseas projects
Landfill mining possibilities in
Australia
• Opportunities to address
existing environmental issues
• Outlook for landfill mining in
Australia?
• Conclusions
Waste 2012 – Landfills - the next mining boom?
Reasons for mining waste
1. Recovery and re-use of landfill cover materials.
2. Upgrade landfill design – lining of previous unlined landfills.
3. Better utilization of landfill airspace through greater compaction.
4. Redevelopment of valuable land.
5. Resource recovery from previous landfilled waste.
Waste 2012 – Landfills - the next mining boom?
Issues to be considered
1. The composition of waste landfilled and the market value of material being
sought.
2. The likely efficiency of the proposed resource recovery process when
applied to the content of the materials being sought.
3. The quality requirements of the products (ie acceptable level of
contamination).
4. The likely environmental and health impacts of the process (asbestos?
hazardous materials)?
5. Logistics – where to do the processing, stormwater and leachate
management during mining and refilling, landfill gas management
6. Ways of managing the amenity issues – noise, dust, odour, traffic, gas
7. Community expectations about long term operation of site – mining,
processing and refilling over long period of time (instead of site closure)
Waste 2012 – Landfills - the next mining boom?
Logistics and other challenges
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Logistics – is the site sufficiently
large for processing plant,
stockpiles of waste to be
processed, stockpiles of processed
recovered materials awaiting
export, stockpiles of waste to be relandfilled, stormwater and leachate
management ponds etc?
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Extent of processing needed to
minimise contamination of the end
product – e.g. to ensure that “clean
fill” does not have asbestos and
foreign objects in it
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Contamination of products
(plastics, metals) rendering them
useless – need for washing plants
may add significant costs and
complexity to site operations
Waste 2012 – Landfills - the next mining boom?
Overseas examples of landfill mining
Barrie, Canada
• long-term waste excavation, screening and recompaction
• 0.5 million m3 of material mined
• mining of unlined cells and placement into new
lined cells
• Reuse of fines for daily cover and engineering
purposes
Perdido MSW landfill in Escambia Country,
Florida
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Upgrade landfill to meet environmental
regulations
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Re-use of landfill airspace.
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Removing sources of landfill gas and leachate
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Reclaiming soils for on-site reuse
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Waste - to – Energy
Waste 2012 – Landfills - the next mining boom?
Planned overseas projects
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Taiwan landfills – The largest planned landfill mining program in the world. EPA
Taiwan plans to excavate all of the country’s 404 landfills and use the material for
energy production (26 large scale incinerators). Other materials such as glass, metal
and flammables will be recovered and rocks and pebbles will be reused for road
paving.
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Remo Milieubeheer landfill, Belgium – expect to use 45% of the landfill’s contents
for recovery of materials, electricity generation and carbon dioxide reduction.
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George Town landfill, Grand Cayman – convert excavated materials to electricity
and address long standing environmental issues (visual, odour, air and noise etc).
Waste 2012 – Landfills - the next mining boom?
Landfill mining possibilities in Australia
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Rural site in NSW – The site is short of landfill cover material, and the main aim of
mining is to recover soil for future use. The age of the waste and the shallow nature
of the landfilling operations suggests that the putrescible component has already
stabilised.
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Metropolitan site – The aim of this project is to recover known materials for
reprocessing (old cars and scrap metal and green wastes), and to extend the landfill
life. After mining, the areas would likely be lined (they are currently unlined), and the
cells refilled to final levels with residual wastes (wastes remaining after processing of
non putrescible wastes).
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Rural site in NSW – The site will be landfilled with baled and wrapped waste, which
will have most of it’s putrescible component removed by separate organics
collection. Metals will have been removed prior to baling. One day, the landfilled
bales of plastics and paper may be worth recovering for energy production.
Waste 2012 – Landfills - the next mining boom?
Case Study 1
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Mining can be used on remote sites to recover airspace and provide
future daily cover (if needed) – metal recovery may be viable
Waste 2012 – Landfills - the next mining boom?
Case Study 2
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Need to consider the overall
staging of the landfilling
operations when planning
mining activities
Have to “finish off’ areas of
the landfill to minimise
stormwater management
issues - mining is difficult in
such areas
Mining is an integral part of
the landfilling and
rehabilitation sequence
Possibility of mono-filling
resources for future
recovery
Waste 2012 – Landfills - the next mining boom?
Opportunities to address existing environmental issues
Existing situation:
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Informal recycling and resource
recovery – scavenging occurs on the
landfill sites.
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Unsuitability of existing landfill locations
in some countries – relocation of waste
or stabilisation of landform is needed
Landfill mining can:
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Recover valuable materials from these
landfills.
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Address landfill safety environmental
issues. e.g. landslips are common after
heavy rains in landfill in Philippines and
many other countries.
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Make sites suitable for other uses, or
rehabilitation/reforestation (if too steep
etc)
Waste 2012 – Landfills - the next mining boom?
Outlook for landfill mining in Australia?
1. Major landfills
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Landfill gas production and
extraction will still be occurring in
30-50 years time at some sites
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Some sites are relatively close to
residential areas
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Significant odour problems if waste
disturbed (high putrescible waste
content)
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Site profiles (heights/slopes) make
mining of waste challenging and
dangerous at some sites
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May become attractive if future
technology enables recovered
plastics to be used for future
energy production
Waste 2012 – Landfills - the next mining boom?
Outlook for landfill mining in Australia?
2. Landfills in rural areas
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Areas of shallow and unlined
landfill cells with poor capping well
suited to mining
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Less landfill gas issues due to
lower putrescible waste content
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Generally isolated from residential
properties
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Gentle slopes and low heights of
landfill mass in “old” areas makes
logistics easier
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May be high concentrations of
metals and other materials worth
recovering in old rural landfills
Waste 2012 – Landfills - the next mining boom?
Conclusions
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Landfill mining can be used to re-create landfill airspace, address existing
environmental issues, obtain scarce cover materials and provide suitable
areas for future land development
Rural landfills may be more suitable for landfill mining than major landfills
A rigorous Cost-benefit Analysis may need to be undertaken before
proceeding on a major landfill mining program
On-site trials may be needed to “prove” that the landfill mining process will
be economically viable
Logistics and environmental management issues need to be carefully
considered and managed during the process
There is huge potential for landfill mining to be undertaken in developing
countries to address legacy issues from past practices
Future energy demands combined with innovative extraction and
processing technologies might make mining of landfills containing plastics
more attractive in the future
Waste 2012 – Landfills - the next mining boom?
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Waste 2012 – Landfills - the next mining boom?