Fate and Transport of Groundwater Contaminants from Landfills

Transcription

1 Fate and Transport of Groundwater Contaminants from Landfills Dan Bruner, PG, Managing Geologist Cascade Earth Sciences Brady Johnson, Hydrogeologist Idaho DEQ 2017 Idaho Solid Waste Association Conference Boise

2 Outline What kinds of solid waste contaminate groundwater? What is in landfill leachate? How do municipal landfills protect groundwater? What happens to leachate in groundwater? How do we detect, define and protect the public from leachate contamination?

3 Wastes of Concern for Groundwater Contamination Any waste that is not inert Inert waste (low leachate potential) Noncombustible, nonhazardous, and non-putrescible solid wastes Likely to retain their physical and chemical structure Resistant to biological attack Examples: Rock, concrete, cured asphaltic concrete, masonry block, brick, gravel, dirt Non-inert wastes that can contaminate groundwater Organic debris yard waste, food waste, etc. Manmade organic chemicals residues from fuel, grease, solvents, refrigerants, etc. Metals chrome, nickel, copper, zinc, lead, arsenic, etc.

4 Typical Leachate Characteristics Source: Waste Management and OBG, 10/27/2016. Landfill Leachate Overview. Presentation to 18th Annual New England Pretreatment Coordinators Workshop.

5 Cap and Cover System Protective Cover 1. Vegetation 2. Top soil 3. Cover soil Composite Cap 4. Drainage layer (aggregate or geonet) 5. Geomembrane 6. Compacted clay Waste Management Inc. Anatomy of a Landfill. Brochure.

6 Working Landfill 7. Daily Cover 8. Waste Waste Management Inc. Anatomy of a Landfill. Brochure.

7 Leachate Collection System and Composite Liner Leachate Collection System 9. Leachate collection layer (aggregate or geonet) 10. Filter geotextile 11. Leachate collection pipe bedded in aggregate Composite Liner System 12. Geomembrane 13. Compacted clay 14. Prepared subgrade Waste Management Inc. Anatomy of a Landfill. Brochure.

8 Advection, Dispersion, and Reactive Transport Modified from Freeze and Cherry, 1979.

9 Concentration Concentration Advection, Dispersion, and Reactive Transport t = 5 years t = 10 years t = 20 years t = 30 years Distance from source C(x) = Time Modified from Freeze and Cherry, 1979.

10 Spatial Distribution of Monitoring Wells Modified from Freeze and Cherry, 1979.

11 Organic Loading Effects on Groundwater Interstate Technology Regulatory Council, Natural Attenuation of Chlorinated Solvents in Groundwater: Principles and Practices. Web-based training.

12 Chorinated Solvents and Degradation Products Cl Cl 2H HCl Cl H 2H HCl H H 2H HCl H H 2H HCl H H C C C C C C C C C C Cl Cl Cl Cl Cl PCE TCE DCEs VC ETH Cl H Cl H H Relative Degradation Rates: PCE >TCE > VC > DCE Interstate Technology Regulatory Council, Natural Attenuation of Chlorinated Solvents in Groundwater: Principles and Practices. Web-based training.

13 Chorinated Solvent Plume Plan View Interstate Technology Regulatory Council, Natural Attenuation of Chlorinated Solvents in Groundwater: Principles and Practices. Web-based training.

14 VOCs - Vapor, Light and Dense Phases Source: EPA 600/R-12/712 Framework for Site Characterization for Monitored Natural Attenuation of Volatile Organic Compounds in Ground Water

15 Conceptual Site Model of Contaminant Transport Source: EPA 600/R-12/712 Framework for Site Characterization for Monitored Natural Attenuation of Volatile Organic Compounds in Ground Water

16 Monitoring Wells Connecting the dots... Source: EPA 600/R-12/712 Framework for Site Characterization for Monitored Natural Attenuation of Volatile Organic Compounds in Ground Water

17 Summary Leachate has a lot of ingredients Caps, covers and liners protect groundwater from leachate Waste segregation in non-municipal landfills is key When in doubt, leave it out Groundwater leachate plumes are complex and difficult to remediate