AREA A/B ENGINEERING REPORT - Waste Management

Geosyntec Consultants
These three subjects are addressed in the following subsections of this appendix. In each
subsection, a convenient green box provides an “at a glance” synopsis of salient technical issues,
summarizing pertinent landfill behavioral characteristics and representing the state-of-thepractice
for modern MSW landfill design and management, along with references for seminal
supporting material from peer-reviewed research, journal articles, and operational practice.
Thereafter, a brief summary of the body of knowledge in support of the synopsis is provided.
C2. LANDFILL PERFORMANCE DURING POST-CLOSURE CARE
C2.1 Technical Synopsis
• Modern landfills are designed and operated to contain liquids and LFG and are
monitored and maintained during active operation and PCC to provide protection of
HHE;
• A performance-based approach for evaluating the need for PCC has both a
regulatory and technical basis and can be incorporated into a management approach
that is protective of HHE for as long as required;
• Future concentrations of landfill gas and leachate constituents can be estimated and the
potential for a landfill to impact HHE can be measured and quantified; and
• Monitoring can be used to demonstrate that making changes to PCC systems or
activities results in acceptable outcomes, and thus confirm the decision to modify or end
PCC.
Seminal Supporting References: USEPA, 1993; ITRC, 2003, 2006a and 2006b; EREF, 2006;
Gibbons & Bull, 2006; Gibbons, et al., 2007.
C2.2 Summary of Supporting Body of Knowledge
It is a commonly held misconception that after the prescribed 30-year PCC period under Subtitle
D has expired, an owner/operator would simply be allowed to stop providing any further care
for the landfill. Another position commonly advocated is that an owner/operator be required to
provide perpetual PCC at MSW landfills. Further, it has been suggested that this care would
involve providing PCC for all elements of the landfill (i.e., the landfill cap, the leachate and LFG
management systems, and groundwater monitoring system). This assumes that a prescriptive level
of PCC will always be required, without evaluating actions taken to biodegrade the organic
waste components (e.g., through bioreactor operations), efforts to evaluate landfill system data
(e.g., LFG quality and production, leachate quality and production, waste settlement, etc.), and/or
verification that these media have not caused impacts to HHE (Houlihan, et al., 2002).
MD10186.doc 144 29 March 2009