Municipal Solid Waste (MSW) Landfill: virtual
tour
What do near surface gas monitoring data tell you?
Main : 1 :
2 : 3 :
4 : 5 :
6 : 7 :
8 : 9 :
10 : 11 :
12 : 13 : 14 : 15 : 16
 Near surface gas data provide the concentrations of gases, usually
just methane, that are moving through the cover of the landfill
into the atmosphere. If laboratory analysis of samples is used,
the results may help characterize the NMOCs being emitted by the
landfill into the atmosphere.
 Near surface gas data may indicate the location of point sources
of relatively high concentrations of landfill gases such as cracks
in the landfill cover. Such information may be useful in locating
permanent soil gas probes for long term monitoring or gas recovery
wells to control the release of landfill gases. Near surface gas
monitoring is also useful inside buildings to locate sources of
landfill gas movement into the building. Cracks and openings into
the buildings may then be sealed to reduce the amount and concentrations
of infiltrating gases.
 However, near surface gas data do not indicate the concentrations
of gases that people may be breathing because of the effects of
rapid dilution that is normally expected of gases traveling from
the surface of the landfill to the 3- to 5-foot height that may
be considered the breathing zone for many people. Furthermore,
near surface gas monitoring is normally only performed on the landfill
or at the boundary of the landfill. Additional dilution of gases
will occur during the travel of contaminants from the landfill
to nearby homes and businesses.
 Near surface gas data may be used in computer air models that
estimate the level of contamination in ambient air in adjacent
communities. The quality and validity of such models for public
health purposes will greatly depend on the quality and validity
of the gas data and site specific meteorologic measurements, as
well as the validity of the assumptions and defaults values used
in the computer model. Air models and estimates that substitute
too many default values for site specific measurements have very
limited value for public health conclusions about breathing zone
concentrations.
Main : 1 : 2 : 3 : 4 : 5 : 6 : 7 : 8 : 9 : 10 : 11 : 12 : 13 : 14 : 15 : 16
|
