Forecasting Long-Term Care Period for Landfills. SWANA 2015 NW Symposium

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1 Forecasting Long-Term Care Period for Landfills SWANA 2015 NW Symposium

2 Forecasting Long-Term Care Period for Landfills Travis Pyle and Michelle Langdon, CH2M SWANA Northwestern Regional Symposium, Troutdale, OR April 2015

3 Burning Questions How can we evaluate landfill stability and progress made towards meeting post-closure care (PCC) requirements? How can we determine the expected PCC period as part of operations and financial assurance? What happens at the end of the PCC? Do nothing and walk-away? Custodial care? 3

4 Agenda Regulations Evaluation of PCC During the Post-Closure Period Stepping Down or Ending PCC Forecasting PCC During Active Operations for Financial Assurance Long-Term Care What Does that Look Like? Questions and Answers 4

5 Regulations 5

6 Federal Requirements 40 CFR Part Post-Closure Care Requirements: Owner/Operator of a MSWLF must conduct post-closure care. Post-Closure care must be conducted for 30 years and consist of at least the following: Maintaining the integrity and effectiveness of the final cover Maintaining and operating the LCRS Monitoring the groundwater Maintaining and operating the LFG system The length of the post-closure care period may be: Decreased by the State if the Owner/Operator demonstrates that the reduced period is sufficient to protect human health and the environment and its approved by the State. Increased by the State if it is determined that a lengthened period is necessary to protect human health and the environment. 6

7 Oregon Requirements Oregon Administrative Rules (OAR) Closure Requirements Post-Closure Care Requirements Financial Assurance 7

8 Oregon Requirements Closed in accordance with 40 CFR 258 Subpart F Post-Closure Care Requirements During the post-closure care period: Maintain grading and drainage Establish and maintain vegetation Operate and maintain leachate and gas collection, removal and treatment systems Operate and maintain each groundwater and surface water monitoring systems Post-Closure care must continue for 30 years after the date of completion of closure of the land disposal site, unless otherwise approved or required by the Department according to OAR (4) and (5). 8

9 Oregon Requirements Closed in accordance with 40 CFR 258 Subpart G Financial Assurance Required - Financial assurance plan must include cost of: Closure of landfill Post-Closure maintenance Contingency for corrective actions Period of 30 years unless exemptions are met Exemptions The landfill poses no significant threat of adverse impact on groundwater or surface water AND The landfill poses no significant threat of adverse impact on public health or safety AND No system requiring active operation and maintenance is necessary for controlling or stopping discharges to the environment. 9

10 Washington Requirements Chapter Washington Administrative Code (WAC) Criteria for Municipal Solid Waste Landfills Closure and Post-Closure Care Following closure, the owner/operator must conduct post-closure care for a period of 30 years or as long as necessary for the landfill to become functionally stable. A landfill is considered functionally stable when it no longer presents a threat to human health or the environment. Post-closure care must consist of at least maintaining the integrity and effectiveness of the final cover system, maintaining and operating the leachate collection system, monitoring groundwater, and maintaining and operating the landfill gas system. 10

11 Washington Requirements Chapter Washington Administrative Code (WAC) Criteria for Municipal Solid Waste Landfills Closure and Post-Closure Care The length of post-closure care period may be adjusted Increased or decreased Consider at least the following factors when determining if a landfill is functionally stable to increase or decrease the post-closure care period. Leachate production and quantity must be such that maintenance and operation of the system can be ceased without posing a threat to human health or the environment Landfill Gas production and composition must be such that maintenance and operation of the system can be ceased while meeting the explosive gas control operating criteria and not post a threat to human health and the environment Settlement and Cover Integrity cover system must attain geotechnical stability for slope and settlement. Vegetation and other erosion controls must prevent exposing the waste or otherwise threaten integrity of the cover system. Cover must be stabilized such that NO additional care is required beyond the post-closure care period. Groundwater Quality must remain in compliance with protection standards of groundwater quality standards. 11

12 Washington Requirements Financial Assurance During the active life of the landfill and during post-closure care, the post-closure cost estimate must be adjusted annually for inflation. The cost estimate for post-closure depends on the duration of the PCC as per the approved post-closure plan 12

13 Evaluation of PCC During the Post-Closure Period 13

Performance-Based Evaluation for Post-Closure Care (EPCC) Evaluation Systems (Modules): Leachate Landfill Gas Groundwater Cap/Physical Stability End Use Environmental covenants Reference: EREF

14 Performance-Based Evaluation for Post-Closure Care (EPCC) Evaluation Systems (Modules): Leachate Landfill Gas Groundwater Cap/Physical Stability End Use Environmental covenants Reference: EREF (Environmental Research and Education Foundation), Project Summary - Performance-Based System for Post-Closure Care at MSW Landfills: A Procedure for Providing Long-Term Stewardship Under RCRA Subtitle D,

15 EPCC Module Evaluations Modules are evaluated in 5 steps: Step 1: Satisfy Prerequisites Step 2: Evaluate Change Step 3: Implement Change Step 4: Monitor Change Step 5: Module Complete 15

Example Landfill Gas Module Site stopped receiving waste in the 1980s, closed in mid-1990s, unlined, clay cap, passive gas venting. No gas hits for 10 years.

16 Example Landfill Gas Module Site stopped receiving waste in the 1980s, closed in mid-1990s, unlined, clay cap, passive gas venting. No gas hits for 10 years. City desires to construct a bike trail through site. Possible to revise PCC land use/environmental covenant to allow this? Sample gas and analyze, and perform ambient air modeling. Risk is acceptable, end use change OK from landfill gas perspective. Continue to monitor gas, monitoring confirms assumptions are valid. 16

17 Example Cap/Physical Stability Module Surveys As-Built 20 years into PCC Legend Pink 5 to 10 Blue 10 to 20 Yellow - >20 17

18 Stepping Down or Ending ng Post-Closure Care 18

Examples of Step-Down PCC Elimination/reduction in groundwater monitoring requirements Downgrading landfill gas active extraction to passive venting Reduction in landfill gas

19 Examples of Step-Down PCC Elimination/reduction in groundwater monitoring requirements Downgrading landfill gas active extraction to passive venting Reduction in landfill gas perimeter monitoring locations and/or frequency Convert from on-site leachate treatment to direct discharge to sewer system, if possible Reduced frequency of cap inspection and maintenance 19

20 Step-Down Monitoring Step-Down procedure to reduce financial assurance requirements and long term financial obligations based on performance metrics Purpose is to provide an incentive for an owner/operator to perform thorough PCC maintenance and track progress Step-Down based on a four-part, performance-based criteria (EPCC) Why: A high-quality program during these years is anticipated to result in lower future maintenance and repair costs and fewer and less costly corrective actions (thereby reducing future risk and liability to the public). 20

21 Step-Down Monitoring Example Site Setting: 40-ha suburban property Operated for over 20 years Leachate pumped from 3 sumps Gas collection system Limited buffer zone 8 groundwater monitoring wells 10 ha geosynthetics cover, 20 ha clay cover Application of a Performance-Based Methodology to Evaluate Optimization and Completion of Post-Closure Care at a Municipal Landfill by Jeremy W.F. Morris, Michael D. Caldwell and Louis P. Bull,

22 Example- cont. Performance based approach (EPCC) Analyzed in year 18 of post-closure Analyzing statistical trends to demonstrate that leachate quality, gas production and settlement are stable and groundwater is not impacted. Approach shows how proactive monitoring can help forecast the level of effort and expected timeline for achieving functional stability and stepping down PCC. 22

23 Example cont. Results Groundwater/Leachate Module - Consistent sampling of leachate and groundwater showed downward trend in concentration of key constituents and showed sampling could drastically stepped down in year

24 Example cont. Results Landfill Gas Module Active gas collection originally planned for a minimum of 30 years due to proximity to neighbors. Gas data showed this could be completed in year 28 when gas production reached de minimus levels (10% of peak). Cap/Physical Stability Module De Minimus level of settlement (rate of 5%) reached in year

25 Forecasting Post-Closure Care Period During Active Operations for Financial Assurance 25

26 Forecasting PCC Period Some states have begun requiring that owners/operators determine the PCC period during active operations for financial assurance How do we do that? Consider step-down of PCC Evaluate: Physical stability (settlement) Leachate quantity and quality Gas production Groundwater quality 26

27 Cap/Physical Stability Cap/Physical Stability Geotechnical Settlement Modeling/Decomposition Field Surveys and Forecasting 27

28 Leachate Leachate Quantity HELP Modeling Field Testing/Calibration 28

29 Landfill Gas Quantity and Quality Estimates: LandGEM Field Testing/Calibration Ambient Air Modeling: Models - SCREEN3 or AERMOD Meet air quality standards at point of compliance NMOC Evaluation - De minimus levels 10% of Action limit 29

Recirculation/ Bioreactor and/or Aeration Waste

30 Strategies to Reduce PCC Period Proactive Strategies (During Active Waste Filling): Leachate Recirculation/ Bioreactor and/or Aeration Waste Screening and Waste Diversion Waste Removal/Landfill Mining 30

31 Financial Assurance Impacts $3.5 Million 40 Year PCC Period $150,000 Annual Cost 3% Rate of Return $3.0 Million 30 Year PCC Period $150,000 Annual Cost 3% Rate of Return $2.6 Million 30 Year PCC Period Step-Down Approach $150,000 Annual Cost for First 20 Years $75,000 Annual Cost for Last 10 years 3% Rate of Return 31

32 Long Term Care What Does That Look Like? 32

33 Long-Term Care Questions Do we really want post-closure care monitoring and maintenance forever? Probably not Who has the long term risks for the site? What type of care might be needed beyond the 30-year PCC period? Short-term extension of say 5-10 years to substantiate stability? Custodial care? How is that funded? 33

34 Custodial Care A Possibility? What is meant by Custodial Care (CC)? The proper and responsible management of the end-use obligations of your landfill, consistent with federal, state and local regulations and land use policies Requires de minimus site management Needs to consider beneficial reuse and land covenants Is Custodial Care a Real Possibility? Yes! 34

35 Final Take Aways There are means and methods to use to evaluate and step-down PCC To be eligible, a site must be well monitored and maintained with good, comprehensive data There are tools for forecasting PCC during active operations for financial assurance Questions remain on what happens after the regulated PCC period in terms of long term care what does it look like beyond 30 years? 35

36 Questions and Answers 36

37 Thank You Contacts: Travis Pyle, P.E. CH2M, Boise, ID Michelle Langdon, P.E. CH2M, Boise, ID

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