Regional Approaches for Termination of Landfill Post Closure

Regional Approaches for Termination of Landfill Post Closure Care Jeffrey Murray, PE, BCEE, Waste Sector Landfill Practice Leader | HDR Dr. Bryan Staley, PE, President and CEO | EREF Wednesday, August 28, 2019 3: 00 PM – 3: 30 PM

SWANA’s New Technical Policy T-9. 3 § “T-9. 3 Termination of MSW Landfill Post Closure Care Requirements” o Developed in Collaboration with NWRA o Reviewed and Approved by Technical Divisions and 70 Member International Board § § § Why now? Where are we? Where can we go? What are we recommending? What else can we do?

Why Now? § RCRA – No Guidance for Termination of PCC § 30 Years PCC Period Are Ending § No Common Defined Approaches o Don’t Need 50 Different Solutions § Support Performance Based Approach o Data, Data

Current US Landfill Post Closure Care Termination Requirements Per Subtitle D with Modifications Functional Stability Organic Stability ALASKA HAWAII

Where Are We? § Little National Dialogue § Slow to Change § Hz. W Guidance Published § What happens after PCC? § Long-term Care § Custodial Care § Undefined

Where Are We? § Organic Stability o Kansas – Trend Analysis o Wisconsin – Stability Plans § Functional Stability o Florida – Methodology o Washington – Risk Analysis o Ohio – New Draft Guidance June 2019 o Virginia – Risk Based Evaluation, Uniform Environmental Covenants Act (UECA)

Where Can We Go? § EPA Guidance? § Regional Approaches o How do you define stability § Prescribed Methodology o Percent Reductions Achieved o Adequate Protection of HHE § Scientific Performance Based Approach

Policy Statement Support use of Performance-based evaluations for PCC termination § Identifies Criteria for demonstrating protection of HHE in absence of active controls § State Programs Should Incorporate the Following: 1. The regulatory PCC period should have a finite term with the length determined on a site-specific basis; 2. The conduct of a performance-based evaluation of the closed MSWLF that relies on the collection and analysis of site-specific data over a defined period can be an effective means of establishing the requisite length of the PCC period on a scientific basis; and 3. The identification and weighting of performance-based criteria should be established along with the technical evaluation approach with input and consensus from appropriate stakeholders.

Ohio EPA Draft Guidance Provides methodology for a systematic evaluation and decision process based on site-specific data and a defined end use of the property https: //epa. ohio. gov/Portals/34/document/general/end of post closure draft. docx § Allows for Step Down of PCC Activity to Evaluate Consequences, 5 Year Check-in § Requires Evaluation of 10 Years of Data Trends o Leachate Quality/Quantity/Rate of Generation o GW Quality and any Assessment Monitoring or Corrective Measures o LFG Generation and Migration trends, locations of structures within 1000’, status of air permits o Cap Integrity and summary of any maintenance performed o PCC Compliance History § Ongoing Obligations after PCC Termination o Authorization to Disturb o Prevention Pollution of Surface Waters – minor maintenance of final cover, surface water diversion o LFG Migration Control o Adhere to Institutional Controls

Recommendations § Groundwater o Demonstrate at or below regulatory levels o No impact after termination of active controls o Indicator parameters § Leachate o Quantity and quality stable o No unacceptable risk to POE o Data • BOD/COD • Ammonia • p. H

Recommendations § Landfill Gas o Generation decreasing o Does not pose risk to HHE at POE o Migration concern o Quality § Stability and Cover Integrity o o Controlling LFG emissions Reduced leachate Little to no settlement Long-term stormwater management

What Else Can We Do? § Work with State Programs and Encourage Regional Approaches § Set the same bar § Instill More Confidence in Mitigation of Risks § Smoother Transition to Long-Term Management and Re-use

Basis for PCC – A Recap § Protection of human health and the environment (HHE) by reducing potential threats to acceptable levels at the relevant point of exposure (POE) § Typically the closest property boundary location where human or ecological receptor could be exposed and receive a dose via potential migration pathway as defined under RCRA (US EPA, 1993) § Authority rests with state agencies to determine sufficient PCC time period, but no guidelines exist that allow agency to determine this § The general assumption is a prescriptive 30 -year term for PCC, but the regulation is actually performance based (40 CFR§ 258. 61 – RCRA Subtitle D)

Approaches for Performance Based PCC § Organic Stabilization § demonstration of a relatively inert waste mass § Functional Stability § considers long-term emissions in context of threat potential WITHOUT active controls § measured at a point between landfill and POE • Goal in either case is going from active postclosure care to a point of custodial or ‘de minimus’ care where HHE is protected

Active Post-Closure Care GP-2 Homes GP-1 MW 1 LANDFILL Gas Flare Station SUMP-3 SUMP-2 Surface Water Discharge GP-3 SUMP-1 Leachate Storage Tank MW 2 Source: Morris & Barlaz, 2017

Custodial or ‘de minimus’ Care Homes Passive Gas Biofilter Constructed Wetland System LANDFILL SUMP-3 Property Boundary Surface Water Discharge SUMP-2 SUMP-1 Source: Morris & Barlaz, 2017 Farmers’ Windmills

Organic Stabilization § Requires near-complete degradation of waste mass (i. e. inert solids in the waste mass) § May offer maximum protection of HHE but also may be ‘overkill’ § Approaches suggested typically do not allow for a ‘step down’ in PCC activities over time § Can imply very long-term (30+ years) or near perpetual care under a regulated program (Scharff et al. , 2011) § Little consideration of cost; likely most expensive option

Demonstrating Organic Stability Chemical Oxygen Demand § Extent of biodegradation § Remaining LFG production § Remaining settlement § Leaching potential § Assessment of future leachate quality COD Concentration (mg/L) § Typically two characteristics of concern for waste 60000 50000 mass: 53800 40000 30000 20000 6550 10000 825 0 0 § Interpretation of how to demonstrate/implement varies 10 20 Bioreactor § Implies characterization of buried solids that is representative of the entire waste mass § No guidance on what testing is appropriate and target levels; wide range of tests could be used (Wagland et al. , 2009) § Trends in LFG, settlement, leachate generation may provide suitable surrogates 30 L/S Leaching 40 50 60

Post-Closure Methane Collection Data Case Study on Solids Analysis BMP of Excavated Samples pure cellulose 414. 8; pure hemicellulose 424. 2 • normalizing to VS is critical (pure cellulose 414. 8; pure HC 424. 2) • Solid analysis shows high variability despite significant downtrend in CH 4 generation Source: Morris and Barlaz, 2017

Functional Stability § Relies on conservative impact assessments to define PCC monitoring and management (Morris and Barlaz, 2011) § Central elements include: § Leachate and LFG management § Groundwater monitoring § Cover maintenance § Eliminates active controls, replacing them with passive measures, once minimal impact target levels have been achieved for each element § Allows for remaining elements of concern to receive focused attention, with the receiving environment and property end-use being important inputs to the evaluation § Optimizes management strategies; minimizes costs

Demonstrating Functional Stability § LFG production is stable or decreasing § < 10% of peak LFG generation § Settlement is essentially complete § <5% annually relative to cumul. total post-closure volume reduction § Leachate quality is stable or improving § satisfy criteria for ‘gateway indicators’ (e. g. BOD/COD < 0. 1) then meet WQS (preferably at source or, failing that, at POC) § Emissions of leachate/LFG will not unacceptably impact HHE via potential pathways to air, groundwater, surface water or vadose zone § Critical aspect of the approach is a confirmation monitoring program, which is designed to track when active controls can be stopped and a full transition from PCC to custodial care can occur Source: S. T. O’Donnell et al. , 2018 Analysis of LFG Collection Using Functional Stability Approach • Plot measured data • Run LANDGEM model for LFG generation • Run LANDGEM model for collected LFG • Align with data so model results match observations, which provides a projection of future LFG collected • Determine when stability target for LFG is achieved

Conclusions § Performance-based strategies tend to be more consistent and are backed by data vs. organics stability strategies which primarily aim to preemptively divert organics away from landfills § Use of performance-based post-closure criteria appears justified and is taking hold based on: § Peer-reviewed science (numerous publications support approach) § Implementation by regulatory agencies (now in 8 states) § State agencies should work collaboratively for consistency § Endorsement by trade associations (SWANA, NWRA) § But chapters should work with state agencies to help develop guidance § Data collection must start early § Ideally when landfill is still accepting waste § Performance-based methodology is more complicated/detailed § Additional work is needed to streamline and simplify how the Credit: www. watershedgeo. com