CE 527 Solid Waste Management
Lecture 4 - Land Disposal – Landfill
 Dr. S. K. Ong
Landfills are an important component in the safe disposal of solid waste and probably the most economical in US
and throughout the world.
Focus will consist of following:
An overview of the landfilling process and current regulatory and operating requirements
Soil liner system and soil cover
Gas Generation and Control
Surface Runoff, Leachate generation and control system and estimation
Definitions
Landfills
are the physical facilities used for disposal of residual solid wastes in the surface soils of the earth
sanitary landfill - disposal of MSW
secure landfill - disposal of hazardous waste
Landfill Liners manufactured and natural materials that lined the bottom and below grade sides of a landfill to
prevent migration of landfill leachate and gases.
Leachate
liquid that collects at the bottom of a landfill - result from percolation or precipitation, water
initially contained in the waste and infiltrating groundwater
Leachate collection and removal system (LCRS)
drainage system to allow easy movement and removal of landfill leachate
Cell
volume of material placed in a landfill during one operating period usually one day
Daily cover
6 to 12 ins of native soil or alternative materials such as compost that are applied to the working
faces of the landfill at the end of each operating period
Lift
a complete layer of cells over the active area of the landfill
Final Lift
last layer of cells plus the landfill final cover
Final cover
multiple layers of soil and/or geomembrane materials designed to enhance drainage, minimize
percolation through the landfill and support surface vegetation
Bench or terrace horizontal landcover to maintain the slope stability and for the placement of surface water drainage
channels and location of landfill gas piping
Landfill closure steps taken to close and secure a landfill site once the filling operation has been completed
Postclosure
refers to activities associated with the long-term monitoring and maintenance of completed landfill
- typically 30 years.
Federal Regulations for Landfills
• principal federal requirements are contained in RCRA Subtitle D and 40 CFR 258 - Criteria for classification of
solid waste disposal facilities and practices.
• other regulations include Clean Air Act for gas emissions and Clean Water Act for leachate disposal
• State of Iowa regulations can be found in IAC Chapter 103
Location Restrictions
airport
- must be 10,000 ft away from an airport runway end used by turbojet or 5,000 ft of any airport
runway end used by only piston-type aircraft; if closer than above restrictions owners must
demonstrate that landfill does not poses a bird hazard to aircraft
- owners or operators proposing to site new landfills and lateral expansion within a five-mile
radius of any airport runway end used by turbojet or piston-type aircraft must notify the affected
airport and Federal Aviation Administration (FAA)
Floodplains
- new, existing and lateral expansions of landfills must demonstrate that the unit will not restrict the
flow of the 100-year flood, reduce the temporary water storage capacity of the floodplain, or result
in washout of solid waste so as to pose a hazard to human health and environment
Wetlands
- new and lateral extensions are not allowed to be located in wetlands unless the owner or operator
can demonstrate that:
(i) no practical alternatives are available with less environmental risk
(ii) construction and operation of landfill will not contribute to violations of applicable state water
quality standards, toxic effluent standards and prohibition under Clean Water Act; jeopardize the
continued existence of endangered or threatened species under the Endangered Species Act of
1973; violate any requirements under the Marine Protection Research and Sanctuaries Act of 1972
(iii) will not cause or contribute significant degradation of wetlands, e.g., erosion, stability and
migration of native wetland soils
(iv) steps taken to achieve no net loss of wetlands
(v) sufficient information is available to make a reasonable determination
Fault Areas
- shall not be located within 200 feet of a fault that has had displacement in Holocene time (past
10,000 years)
Seismic Impact Zones - new and lateral expansions shall not be located in seismic impact zones, unless the owner or
operator demonstrates that all containment structures, including liners and LCRS and surface
control systems are designed to resist the maximum horizontal acceleration in lithified earth
materials for the site. Lithified materials - all rock, including all naturally occurring and naturally
formed aggregates or masses of minerals or small particles of older rock that are formed by
crystallization of magna
Unstable Areas
- owners of new, existing and lateral expansions of landfills located in unstable areas must
demonstrate that engineering measures have been incorporated into the MSWLF's design to ensure
the integrity of the structural components of the MSWLF. Unstable area means a location
susceptible to natural or human-induced events or forces capable of impairing the integrity of some
or all of the landfill structural component e.g., areas that prone to landslide, sinkhole formation in
karst terrain
Types of Landfill
(i) conventional landfills for commingled MSW
(ii) landfills for milled solid wastes
(iii) monofills for designated or specialized wastes
Classification of Landfills
Most widely accepted classification system for landfills
Class 1
Class II
Class III
Hazardous waste
Designated landfill (nonhazardous)
Municipal solid waste
Landfilling Methods
Excavated Cell/Trench Method
Area Method
Canyon/Depression Method
secure
sanitary
Operating Criteria
(i)
Exclusion of hazardous waste
- must implement a program at the facility to detect and prevent disposal of hazardous waste and
polychlorinated biphenyls (PCBs). Program should include: random inspections, records of inspections,
training of personnel to recognize, notification procedures if hazardous wastes is located at the landfill
(ii)
Cover material requirement
- must cover disposed solid waste with six inches of earthen materials at the end of the each operating day
to control disease vectors, fires, odors, blowing litter and scavenging or alternative materials of alternative
thickness approved by the Director
(iii)
Disease vector control
- must prevent or control on-site population of disease vectors using techniques appropriate for the
protection of human health and the environment
(iv)
Explosive gases control
- must ensure that the concentration of methane gas generated by the facility does not exceed 25 percent of
the lower explosive level limit for methane in the facility structures (excluding gas control and recovery
system components)
- must implement a routine methane monitoring program
(v)
Air criteria
must ensure that the units do not violate any applicable requirements developed by under a state
implementation plan (SIP) approved or promulgated pursuant to the Clean Air Act open burning is
prohibited
(vi)
Access control
- must control public access and prevent unauthorized vehicular traffic and illegal dumping of wastes
(vii)
Run-on/Run-off control system
- design, construct and maintain a run-on control system to prevent flow onto the active portion of the
landfill during the peak discharge from a 25- year storm
- a run-off control system from the active portion of the landfill to collect and control at least the water
volume resulting from a 24-hour, 25-year storm
(viii)
surface water requirements
- shall not cause a discharge of pollutants into waters of the US including wetlands that violates the Clean
Water Act cause a discharge of a nonpoint source of pollutant to waters
(ix)
Liquid restrictions
- bulk or noncontainerized liquids waste may not be placed in the MSWLF unit unless:
the waste is household waste other than septic waste
the waste is leachate or gas condensate derived from MSWLF unit and the MSWLF is designed
with a composite liner and a LCRS
(x)
Record Keeping
must record and retain near the facility an operating record on the following:
- location restriction
- inspection and training records
- gas monitoring results
- MSWLF unit design documentation
- monitoring and testing results
- closure and post closure care plans and any monitoring, testing or analytical data
Design Requirements for Soil Liners
• a design approved by the Director of an approved state that will ensure that the concentration values in Table 1 will
not be exceeded in the uppermost aquifer at the relevant point of compliance.
The relevant point of compliance specified by the director of an approved state shall be no more than 150
meters from the waste management unit boundary and shall be located on land owned by the owner of the
MSWLF unit.
• with a composite liner and a leachate collection system that is designed and constructed to maintain less than a 30cm depth of leachate over the liner
Composite liner means a system consisting of two components: the upper component must consists of a
minimum 30-mil flexible membrane liner (FML) and the lower component must consist of at least a twofoot layer of compacted soil with a hydraulic conductivity of no more than 1 x 10 -7 cm/sec.
FML components consisting of high density polyethylene (HDPE) shall be at least 60 mil thick.
Final Cover Requirements
• must install a final cover system that is designed to minimize infiltration and erosion. The final cover system must
be designed and constructed to:
(i) have a permeability less than or equal to the permeability of any bottom liner system or natural subsoils
present, or a permeability no greater than 1 x 10 -5 cm/sec, whichever is less, and
(ii) minimize infiltration through the closed MSWLF by the use of an infiltration layer that contains a
minimum 18-inches of earthen material, and
(iii) minimize erosion of the final cover by use of an erosion layer that contains a minimum 6-inches of
earthen material that is capable of sustaining native plant growth.