AREA A/B ENGINEERING REPORT - Waste Management

Geosyntec Consultants
leachate volumes from accumulating on the liner at a volume that could compromise liner
effectiveness. Maintaining a minimal head on the liner system significantly reduces the possibility
of leachate seepage to the environment. Any deviations from this restriction must be corrected
immediately and documented in site operational records. Significant deviations may be
reportable to the state regulatory agency.
Active environmental monitoring is required at key locations around the landfill. Four types of
monitoring systems are designed to detect a system upset from either LFG or leachate into the
four primary media:
• Groundwater monitoring;
• Surface water monitoring;
• Lateral gas migration monitoring in the shallow unsaturated subsurface (known as the
vadose zone); and
• Surface emissions monitoring (SEM) to detect migration of gas through the cover system to
ambient air.
To assure accuracy, monitoring and sampling at Subtitle D landfills is performed by qualified
field personnel following strict chain-of-custody procedures for sample collection and data
tracking. Sample analyses are conducted at certified independent laboratories under high
quality standards. Where on-site monitoring is required, samples are collected using appropriate
outdoor monitoring equipment following well-defined protocols, including requirements for routine
equipment calibration, collection of several scanning measurements in real time, and other
conditions specified in the facility’s permit.
Data are evaluated using statistical approaches and other scientific techniques as mandated by
the state regulatory authority, employing evaluation techniques specifically developed for
performing quantitative, technically-defensible evaluations of monitoring data. These evaluations
are important because they can provide reliable predictions of future concentrations based on
past and current data, and afford a baseline from which to identify inconsistent results. The
results of environmental monitoring are used to confirm the predictions of future trends in leachate
or LFG quality and quantity, and to confirm that changes in landfill operation or maintenance
have not resulted in an unexpected outcome or upset of the landfill containment system.
Monitoring data and evaluations must be reported to the overseeing regulatory agency in a
timely manner in accordance with permit conditions.
2.2.6 Closure
Once the landfill has reached its final permitted waste capacity and active operations have
ceased, the landfill is closed consistent with detailed regulations and in compliance with the
facility’s approved closure/post-closure plan. A final cover system is constructed to perform the
following functions:
MD10186.doc 31 29 March 2009