|
Background
Unmanaged
landfill gas can not only be a hazard to human health and the environment,
but also cause structural problems to the landfill itself. If allowed
to accumulate, landfill gas can result in fire, explosion, and hazardous
breathing conditions. Landfill gas can also cause odor problems and
detrimental effects on vegetation.
The
U.S. Environmental Protection Agency promulgated Subtitle D regulations
requiring routine monitoring for methane gas accumulation and migration.
In compliance with the regulations, methane gas detection monitoring
programs must be implemented at all regulated municipal solid waste
landfills (new, existing, and lateral expansions).
Experience
Davis
& Floyd, Inc. has been actively engaged in environmental monitoring
and compliance at county-owned municipal and industrial solid waste
landfills. In addition to traditional landfill monitoring activities,
we are intimately familiar with the evolving regulatory and technical
aspects of landfill gas monitoring and management. We have developed
and implemented landfill gas monitoring programs and designed methane
gas recovery systems.
Requirements
Landfill
gas monitoring programs must be sufficient to provide for detection
of gas migration and protective of human health and the environment.
At a minimum, quarterly methane gas monitoring is required for detection
purposes. More frequent monitoring may be required based upon site conditions
such as:
-
Landfill design changes (i.e. capping, closure or expansion)
-
Operational changes to leachate collection and recirculation systems
and methane gas control systems
-
Increase of methane concentrations at detection monitoring
locations
The regulations also require that methane concentrations be maintained
below certain levels with respect to explosion hazards. Hourly or continuous
methane monitoring may be necessary if methane concentrations exceed
the explosion limits. Under these conditions, the regulations also require
that the following specific actions be taken:
- Implementation
of immediate steps to protect human health, including evacuation
of personnel from the facility and notification of appropriate authorities
responsible for dealing with explosive emergencies
- Documentation
of
methane concentrations and other pertinent information in the operating
record of the landfill
-
Development and implementation of a remediation plan that describes
the nature and extent of the problem and the proposed remedy, and
notification of the appropriate regulatory authority that the plan
has been implemented
Development
of landfill gas monitoring programs must be based on site-specific conditions
such as:
- Soil
conditions (i.e. porosity, permeability, and moisture content)
- Hydrogeologic
conditions (i.e. thickness of unsaturated zone, continuity of permeable
units, and presence of impermeable barriers)
- Hydraulic
conditions (i.e. depth to groundwater, infiltration potential, and
groundwater discharge and recharge zones)
- Facility
design and changes (i.e. phasing of construction, installation of
a cap, whether facility is lateral or vertical expansion)
- Location
of facility structures, property boundaries, and structures on adjacent
properties, and adjacent land uses
|
