1. Long-Term Care After 30-Year Post-Closure Period
Don Hullings, PE
Thank you.. Blah blah….. I have been looking at this for a while and now NYSDEC has front it to the forefront
January 31, 2017

2. Post-Closure Care Regulations
40 CFR (Subtitle D) 30 years of post-closure care (more or less)
I think we are know about federal subtitle regs and how they are adopted by individual states. Post-closure care is required and while most people plan for 30 years,, it can be shorter although unlikely, but quite possibly longer. How much longer can be determined by the state on an individual basis
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3. Custodial Care Regulations
Draft NYSDEC (b) Introduces custodial care Begins when Department determines that the facility poses a significantly reduced threat to public health or the environment and the environmental monitoring and maintenance can be reduced
NYSDEC has introduce custodial care to begin the discussion of what happens after 30 years. Focus now on “significantly reduced threat”. So what do you think that means?
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4. Custodial Care Regulations
DEP Guidance Document Performance Based LTC modeling “Functional Stability”
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5. Custodial Care 4 Basis Elements: Leachate Management Gas Controls
Groundwater Mon
Final Cover Maintenance
This is my read of the new regulations. What are the 4 basic elements of PCC.? The four basic tenets from Subtitle D and adopted here by NYSDEC, and you will be hearing these a lot, are ……… The NYSDEC has gone so far as to suggest what custodial care may look like.
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6. How Do You Get to Custodial Care?
What is a significantly reduced threat? What is functional stable (does not pose unacceptable threat)?
Trend Analysis vs. Absolute criteria
Internal (waste properties) vs. External (emissions)
So when does PCC end and CC begin? NYSDEC says significantly reduced threat, others say functionally stable which is defined as not posing an unacceptable threat.The threat is to HHE, another term you need to begin to embrace. So do we have an absolute criteria for unacceptable threat (like BOD < ____, settlement less than ____)? No, but I will throw a couple of things out later. What you need to understand now is that your “threats”, at a minimum, need to be trending down. Also, we can look at the waste itself to evaluate stability or look at “emission”, in this case meaning more indirect indicators. The consensus in the industry, because of the heterogeneity of waste and difficulty with meaningfull samples, is to look at external indicators (gas emission, leachate quality,etc.)
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7. Performance Based Criteria
Establish Sufficient Data
Evaluate Change
Implement Change
Monitor Change
Establish appropriate level of care
So here is where the industry seems to be headed based on work by Environmental Research and Education Foundation and the Interstate Technology Regulatory Council. It’s a performance based critieria using trend analysis, modeling, monitoring, and at the end some judgment. <<read bullets quickly>>How would you apply this to a real landfill?
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8. Example of Process Shut Down Active Gas Collection System
Establish that gas generation has decreased significantly
Model gas pressures/emissions if system were turned off
Turn off active gas system
Monitor pressure, emission, etc.
Decide that active system is no longer required
Self-explanatory
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9. Four Elements
Where industry seems to be headed is back to the beginning:
Leachate Management
Gas Collection
Groundwater Monitoring
Effectiveness of Cover
So we are back to looking at the four basic elements and how we could effect change in each one in a step-down process heading to custodial care. This method envisions that incremental steps may be necessary so that the site may not switch from what was happening initially at PC to CC.
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10. Systems Criteria for Stability
Leachate Collection Evaluate quality of leachate. Potential criteria for “stable” leachate: 1) Direct discharge standards 2) Groundwater Protection standards 3) Clean-up Standards 4) Specific Modeling
So let’s look at how the functional stability may be evaluated for each element.
The easiest thing to do with leachate is to compare the quality to some standard. What Criteria should be used? the problem is that even after 30 years leachate is unlikely to meet water standards. Looks like we are in for some fate and transport modeling and maybe a little treatment
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11. Systems Criteria for Stability
Leachate Treatment
Switch to on-site passive treatment:
Natural Attenuation
Biofilters
Wetlands
- What about bathtub effect?
If some kind of treatment is needed, CC care means passive (no power, no maintenance, very limited involvement). What about the bathtub effect and how do you get leachate out?
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12. Systems Criteria for Stability
Landfill gas 1) Methane Below explosive limits 2) Surface Emissions Monitoring – <500 ppm 3) Gas pressures do not destabilize cover 4) Odor 4) Modeling based on gas generation curve with site-specific trend data
Landfill gas may be a little easier to address. Some landfills have already switched from active to passive systems so there is more understanding in this area
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13. Systems Criteria for Stability
Groundwater 1) No migration demonstration (40 CFR ) 2) Travel time from WMU to POC is great (stagnant water) 3) No potential for leachate to impact GW at POC 4) Site appropriate modeling
So for groundwater again we have to make some kind of demonstration.
Simply having a clean groundwater monitoring record may not be enough to enter CC, but have any current hits to GW will certainly preclude you
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14. Systems Criteria for Stability
Final Cap 1) No impact on other systems if cap wasn’t there 2) Reduced effectiveness of cap would result in no impact 3) Cap required for others systems to meet criteria
The cap stability is a function of how it impacts the other 3 elements. The amount of maintenance depends on how much the cap is needed
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15. Retroactive Case Study
Mohawk Valley Landfill: BOD < 100 mg/l BOD/COD < 0.1 Annual settlement < 5% of total
This methodology has already been applied to a landfill retroactively. At the Mohwak Valley Landfill PCC reductions had been made and a lot of data was available. In study, the question was asked of how a reduction could have been made and evaluated and the answer was compared to what the landfill had already done. Some criteria was established including 5% settlement, BOD<100 mg/, BOD/COD<0.1
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16. Florida Guidance Document
SWM February 20, 2016 Data for at least 10 years beginning 3 years before closure Stop testing for parameter if <50% MCL or < MCL for 5 years Begin settlement evaluation after gas production <20% peak
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17. Cost of Perpetual Care
Large Landfill Example from New York Total Post-Closure Cost for 30years (PV) $13.2 million Fund Needed at Year 1 for Perpetual Care after 30 years (assume $0 leachate cost) - $14.9 million $14.9 million Barely over 10% increase
So in the large landfill example, the total cost of PCC for 30 years is $17.4 million. If you were to create a PCC fund which could be invested with a return of 2% above inflation, you would need $13.2 million at the beginning of PC. If you could end leachate treatment at the end of PC, $14.9 million in the fund would be enough for PERPETUAL CC. From this perspective, the cost of custodial care can be low
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18. ? What Can You Do Now? Begin asking questions:
Historic groundwater impacts?
How is the leachate quality trending?
Where are you on Gas Curves?
Cover integrity?
Distance to POC?
How much longer will you be operating (collecting revenue)?
Have you operated as a bioreactor? ?
What can you be doing now?
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19. What Can You Do Now? Get data….and then get more data:
Leachate quality
Leachate quantity
Gas Collection
Gas quality
Settlement information
Groundwater
Trending analyses will be large part of the evaluation – gather it now
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20. What Can You Do Now? Consider change in operations. Perhaps Bioreactor
Improve leachate quality (except for ammonia)
Reduce long-term gas generation
Reduce post-closure settlement
What changes can you make in your operations to help be functionally stable? A bioreactor hits on the 4 elements – better quality leachate, lower gas production (in the long term), long-term settlement reductions
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21. What Can You Do Now?
Intermediate/partial closure – EGC? Begin to test the impact of closure on trend analyses
Can you begin evaluating reductions in PCC? One way is to test the impact of cover
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22. Questions?
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