Transcript Training - Brock University

Landfills: An Overview
TREN 3P14:
Sustainable Integrated Waste Management
David T. Brown
Dept. of Tourism and Environment
Brock University
St. Catharines, Ontario L2S 3A1
References: O’Leary, Philip & Patrick Walsh. Landfill Course. Waste Age, January 2002 – January 2003.
Landfill
• conceived in the 1960s as a planned
method of solid waste disposal
• prior to that, municipal solid waste
disposed of in organized or unorganized
open dumps.
• waste may not have been covered
• likely was burned as part of the disposal
• practice
Landfill
1970s – North America and Europe:
• initiatives made to improve solid waste
disposal practices
Sanitary Landfill
• an engineered facility for the disposal of
municipal solid waste (MSW) designed
and operated to minimize public health
and environmental impacts
Photo: www.gin.hr/ project_jak.htm
Sanitary Landfill
• typical landfill consists of several cells in
which the waste is systematically placed
• Landfill base usually consists of a liner
(clay or synthetic) that minimizes the
leakage of liquid waste materials and
leachate into groundwater system
Installation of synthetic landfill liner
Photo: www.gin.hr/ project_jak.htm
First cell of landfill (area method)
Access
ramp
Refuse
Photo: David T. Brown
Sanitary Landfill
• Waste built up in layers and compacted
• Wastes covered daily with soil,
geomembranes, or other cover
materials to prevent lightweight wastes,
dust, and odors from escaping and to
discourage vermin
Photo: Bung-orn Thirapoj
Weigh Station
Photo: David T. Brown
Weigh Scale operator
Photo: David T. Brown
Truck on weigh scale at entry
Photo: David T. Brown
Load cell to weigh truck
Photo: David T. Brown
Landfill liner detail
Synthetic liner
Photo: David T. Brown
Sanitary Landfill
• Modern landfills are sophisticated
facilities that require millions of dollars
to build
• Services provided often valued at
millions of dollars per year
Sanitary Landfill
• Typical landfill operates between 10 and
20 years
• During this period, waste in the landfill
undergoes complicated decomposition
processes
Sanitary Landfill
• Decomposition results in the release of:
– liquids (leachate)
must be contained in the landfill and
treated prior to release
– gases
must be managed as they escape through
the landfill cover, or are collected for
burning or storage
Lined landfill section
Liner
Ponded water
Sand cover to protect
and retain plastic liner
Photo: David T. Brown
Leachate retention pond
Culvert
Photo: David T. Brown
Access well in new section
Liner
Access well
Photo: David T. Brown
Sanitary Landfill
Various options available to landfill
operators regarding:
• Preparation of waste before it
arrives at the landfill
• Compaction procedures for waste
• Alternatives for managing leachate
and gas
Technological innovations
Recent technological innovations include:
• improved groundwater monitoring and leachate
collection systems
• Improved gas monitoring and collection systems
– meet air pollution control standards
– facilitate energy recovery
• installation of geosynthetic covers
• introduction of large waste compaction equipment
• Development of alternative cover materials installed
during final closure
Leachate collection conduits
Photo: www.gin.hr/ project_jak.htm
Bioreactor landfills
• Landfill is operated as a managed treatment facility
• Natural decomposition process accelerated to
– reduce waste volume
– increase the amount of waste that can be
landfilled
• Bioreactors expected to reduce long-term emissions
into the groundwater or the atmosphere.
• Several bioreactor landfills being operated on a
limited basis in the United States and in Western
Europe.
The Life of a Landfill
Phase 1: Site Selection and Investigation
• sites evaluated from geotechnical and
environmental standpoints
• initiation of a public participation program,
to openly communicate with the public
and minimize potential landfill opposition
The Life of a Landfill
Phase 2: Design and Regulatory Approval
• detailed plans and specifications for
facility are prepared
• regulatory approvals are obtained
• financial commitments are received
• construction is initiated
The Life of a Landfill
Phase 3: Site Construction
• development of support facilities
• development of the landfill’s first one or
two cells
Phase 4: Operation
• landfill opened and operated over a
period of years
• additional cells constructed as needed
The Life of a Landfill
Phase 5: Site Closure
•
•
When cells are filled to capacity they are
closed and monitored
Final closure often involves site remediation
Phase 6: Long-Term Care
• Monitoring for 30 years after closure
• Owner / operator responsible for remedial
action and facility maintenance
Environmental Considerations
Groundwater Quality
• If landfill not properly lined, waste can
escape into groundwater
• Most landfills constructed with a
combination of low-permeability
compacted soil and geomembranes
Ref: O’Leary, Philip & Patrick Walsh. 2002. Land Disposal of MSW: Protecting Health & Environment. Waste Age- February 2002, pp. 38-43.
Photo: David T. Brown
Environmental Considerations
Wetland and Stream Protection
• Surface runoff detrimental to adjacent
wetlands and streams
• Chemical, organic, and sediment
contamination are all problematic
• May be reduced or eliminated with
proper design and management
Photo: David T. Brown
Photo: David T. Brown
Photo: David T. Brown
Environmental Considerations
Air Quality
• Odours
• Gaseous emissions:
– direct from the waste (volatile
solvents, fumes, odours)
– from anaerobic decomposition (e.g.,
methane)
Environmental Considerations
Air Quality
• Blowing grit, dust, lightweight litter
• Combustion gases, smoke, and
particulates, if landfill catches fire
Photo: David T. Brown
Environmental Considerations
Greenhouse Gases
• Landfills emit significant quantities of
methane and carbon dioxide
• Control mechanisms are being
mandated at the provincial level
(Canada) and national levels (USA)
Landfill gas
liquification facility
Photo: David T. Brown
Landfill gas
combustion stack
Safety Considerations
Explosion Potential
• Landfill gas is a potentially explosive
combination of methane and carbon
dioxide
• Explosive landfill gas may migrate
underground into buildings, or collect in
explosive pockets onsite
Safety Considerations
Slope Stability
• landfills have become larger; heights have
significantly increased => leads to slope
stability concerns
• Steep slopes can
fail, with
catastrophic
results.
Photo: Bung-orn Thirapoj
Photo: www.gin.hr/ project_jak.htm
Photo: www.gin.hr/ project_jak.htm
Safety Considerations
Slope Stability
• earthquake activity can also potentially
cause slope failure at a large landfill
• also an issue at landfills that receive
specialized waste
e.g. if wastes contain significant
amounts of water, slope stability
decreases
Safety Considerations
Worker Safety
Materials in landfills may be hazardous.
Workers need protection from:
•
•
•
•
•
•
•
•
Sharp, hazardous, infectious or pathogenic wastes
Dust and particulates
Noise and hazards from vehicles and equipment
Fire and explosion
Vermin
Volatile substances, odours
Extreme weather, wind, high and low temperatures
Construction accidents
Photo: Bung-orn Thirapoj
Decomposition in landfills
• The decomposition process is a
principal driving force in the
development, operation and closure of a
landfill
• MSW contains organic material that
naturally decomposes when landfilled
Decomposition in landfills
Two phases:
• Aerobic
(oxygen present)
• Anaerobic (stages 1 and 2)
(little or no oxygen present)
Photo: Bung-orn Thirapoj
Organic refuse
Photo: David T. Brown
Photo: Bung-orn Thirapoj
Decomposition in landfills
Both aerobic and anaerobic phases have
byproducts:
Aerobic phase:
• carbon dioxide
• contaminated water that flows toward the
base of the landfill
Anaerobic phase:
• methane
• carbon dioxide
• liquid byproducts with various contaminants
• decomposition process continues for many
years
• trace quantities of materials which may
impact the environment are contained in both
landfill gas and leachate (e.g., metals in
leachate; VOCs, greenhouse gases)
• trace materials are generated until the landfill
becomes completely stabilized (between 300
and 1,000 years)
Photo: Bung-orn Thirapoj
Photo: www.gin.hr/ project_jak.htm
Photo: www.gin.hr/ project_jak.htm
Photo: www.gin.hr/ project_jak.htm