1. Performance Based System for Determining Post Closure Care (PCC) at Florida MSW Landfills Southwest Landfill, Alachua County, Florida Dr. Debra Reinhart Asawari Kulkarni

2. Outline Performance based methodology Timeline Project status Groundwater Module  Groundwater monitoring well locations  Statistical comparison  Groundwater data analysis: VOC  Metal analysis and results  Summary Next

3. Performance Based Methodology Developed by EREF (Geosyntec contractor) Comprised of four modules:  Leachate Module  Groundwater Module  Landfill Gas Module  Cap Module

4. 1988 1989 1990 1991 1992 1993 2000 1999 1998 1997 1994 1996 1995 Operation Began: Constructed and started accepting waste Horizontal Injection for Leachate Recirculation Initiated Recirculation via Infiltration Ponds Started tires separation/ shredding and recycling Final Closure 2001 2002 LFGTE initiated Site history and timeline

5. Performance Based Methodology Leachate Module  Analysis of leachate monitoring data  Data from 1993-2007  For 90% ND, reduce monitoring frequency and then discontinue

6. Performance Based Methodology: Leachate Module Outcomes Organic contaminants: Reduce and then discontinue monitoring  Declining and approaching MCL (e.g. acetone)  Detected always below MCL ( e.g. styrene or naphthalene)  Following a significant reducing trend and are below MCL ( e.g. toluene, xylene)

7. Performance Based Methodology: Leachate Module Outcomes Trends followed by metal contaminants:  Reduce and discontinue monitoring for metals always BDL ( only copper)  Continue monitoring for arsenic, iron, chromium: Concentration and mass variations depending on the leachate flows

8. Project Status Leachate Module Groundwater Module Landfill Gas Module Cap Module

9. Groundwater Module Analysis of historical groundwater monitoring data Helps in making a decision on optimizing/terminating current groundwater monitoring plan during PCC Data obtained from Southwest Landfill consultants, Jones, Edmunds & Assoc.

11. EPA Recommended Comparison Options Comparison with historical data from same well : Intra-well comparisons Comparison With background wells : Inter-well Comparison Comparison with MCL Control Charts Confidence Interval Method Tolerance Interval Test of proportions

12. ND > 50%? Yes No Data Test of proportions Confidence Interval (CI) Are data normal? Yes Are Log data normal? Yes Normal CI Log-normal CI Non-Parametric Approach Non-Para CI Yes

13. Groundwater Monitoring Data Monitoring data available from 1994-2007 Around 200 parameters are monitored every year CHEMSTAT is used for statistical comparisons Minitab 15 for graphical representations

14. Groundwater monitoring data √ Statistical analysis tools √

15. Frequently Detected Contaminants: VOCs Number of Detects VOCs detected at SWLF

16. Frequently Detected VOC: Acetone Found only in well SW-2D Detected before year 2000 May be due to 7 acres Class III disposal area to the south

17. Location of well SW-2D: Acetone

18. Frequently detected VOC: 1,4-dichlorobenzene Wells SW-4D, SW- 7D and SW-10D Found in Compliance wells

19. Frequently detected VOC: 1,4-dichlorobenzene

20. Frequently detected VOC: Chlorobenzene Second most frequently detected contaminant Detected in SW-4D and SW-10D Probably comes from degradation of dichlorobenzen e in anaerobic conditions Increasing trend

21. Frequently Detected VOC: Vinyl chloride

22. Found consistently in well SW-4D MCL – 1 ug/L Vinyl chloride concentration > MCL May come from dechlorination of chlorinated ethenes under anaerobic conditions VC degrades better aerobically as compared with anaerobic conditions Declined after 2001 Significant contamination when compared with MCL and background wells Never detected in leachate ( always BDL)

23. Less frequently detected VOC 1,2-dichlorobenzene Benzene C-1,2-dichloroethene Chloroethane Chloroform Chloromethane Dichlorodifluoromethane Methylene chloride Tetrachloroethene

24. Recommendations for VOCs Reduce, then discontinue monitoring frequency:  1,2-dichlorobenzene  Benzene  C-1,2-dichloroethene  Chloroethane  Chloroform  Chloromethane  Dichlorodifluoromethane  Methylene chloride  Tetrachloroethene

25. Recommendations for VOCs Continue monitoring for vinyl chloride  Consistent detection frequency  Above MCL

26. Metal Analysis: Metal Detection Frequency

27. MetalTMELeachate Range GW Range, µg/LMCL, µg/L UpDown Antimony3981-410.7-2.50.7-96 Arsenic7640-2801.43-271.2-3210 Barium40119-502-211-4202000 Cadmium7616-140.4090.18-135 Chromium7610-19016-181.25-53100 Cobalt3740.2-250BDL0.4-40NA Copper42111-31002-150.6-1101300 Lead7611.5-503.6-5.81-49.215 Mercury7600.035-1.50.1-0.60.087-1.62 Nickel39797-7804-140.7-72100 Zinc41025-5001.4-1101-1300NA

28. Metal Recommendation Reduce, then discontinue metal monitoring frequency: Antimony Chromium Copper Barium Nickel Cobalt Mercury

31. Metal Recommendation Continue monitoring for:  Arsenic  Cadmium  Lead

33. Metal Recommendation Reduce, then discontinue monitoring of metals at wells:  SW-9D  SW-7D  Sw-12D  SW-P1  SW-2D

34. Metal Recommendation Sampling private wells offsite but down-gradient to track potential transport of heavy metals

35. Summary Analysis of groundwater monitoring data completed Future monitoring limited to few metals and VOCs 5 monitoring wells can be eliminated from metal monitoring Off-site monitoring for metals

36. Next Landfill gas module Landfill gas quality and quantity Impact on human health and environment

37. Thank you