AREA A/B ENGINEERING REPORT - Waste Management

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• Leachate treatment options (i.e., recirculation into waste, pre-treatment systems, direct
POTW discharge, use in existing natural wetlands, creation of new natural or man-made
wetlands, or tree-farming).
Climate conditions have a direct effect on leachate generation rates and
quantities, and indirectly affect available treatment options or operational
performance of the leachate treatment systems (e.g., some treatment
systems are efficient for treating small quantities of leachate but are not
economical for large volumes, while many treatment systems are reliant on
biological processes which may not perform well in cold climates). Sitespecific
conditions and location of a landfill affect layout restrictions (e.g., if little space is
available for leachate management/treatment features, then systems requiring large areas are
obviously not suitable) and effluent (treated leachate) discharge options and permit limitations
(e.g., small, low-flow surface water systems with highly sensitive or pristine ecosystems will impose
stringent limits on effluent quality). Effective leachate management requires assessment of the
operational and post closure lifetime of a landfill, taking account of expected changes in leachate
quantity and quality over time.
While leachate management strategies are critically important during the operational life of a
landfill, sustainable leachate management strategies at the managed modern landfill consider
long-term solutions that have added benefits like the production of “green energy” (i.e., gas to
energy plant) or development of wetlands or tree farms that provide community benefits and
provide for ongoing protection of human health and the environment long after the landfill closes.
Available leachate management alternatives can be broadly categorized as follows:
• Store untreated leachate in onsite tanks, then:
o Truck offsite for disposal at a POTW for treatment with municipal wastewater; or
o Direct discharge to a sewer connection to a POTW;
• Recirculate untreated leachate back into the landfill;
• Use untreated leachate for application in natural or constructed wetlands, tree farming,
etc.; or
• Provide onsite leachate treatment prior to disposal or discharge consistent with the above
options.
The first alternative has historically been the most widespread approach adopted at Subtitle D
landfills, although other options are becoming increasingly common. It should be noted that,
although the primary objective of recirculation is generally provision of cost-effective onsite
management and treatment of leachate, a secondary objective is often accelerated
biodegradation of the waste mass and LFG generation (as discussed in Section 7). Leachate can
be delivered back into the waste mass through a variety of methods, primarily spraying at the
active face, surface infiltration ponds, vertical injection wells, horizontal gravity drainage
MD10186.doc 42 29 March 2009