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Today’s Talk
- Why did I write this guidance?
- What has been the result?
- Answer some frequently asked questions.
Methane at Bioremediation Sites Todays Talk Why did I write this - - PowerPoint PPT Presentation
Methane at Bioremediation Sites Todays Talk Why did I write this - - PowerPoint PPT Presentation
Methane at Bioremediation Sites Todays Talk Why did I write this guidance? What has been the result? Answer some frequently asked questions. Why bother? I havent noticed any remediation sites exploding. Groundwater data where
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Why bother? I haven’t noticed any remediation sites exploding.
- Groundwater data where methane exceeds its
solubility.
- Monitoring well methane gas exceeding the
methane lower explosive limit (LEL).
- Documented soil gas/sub-slab monitoring
points exceeding the methane LEL.
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Ethanol in Indianapolis 30 mg/L Ground water methane!
Date Methane mg/L 02/12/08 22.490 09/16/08 20.139 02/04/09 12.526 09/10/09 23.282 03/02/10 19.503 09/13/10 31.211 03/22/11 19.606
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Please Plan Ahead
- Be aware you might generate high levels of
methane.
- Be prepared to address possible methane
issues in your remediation work plans.
- Consider the increased cost if you have to
mitigate.
- Make sure it’s technically feasible if necessary
to mitigate.
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Initial Thoughts
- Goal is to figure out if methane has enough
- xygen to attenuate before it has ‘space’ to
collect.
- Precautionary measure for receptors might be
advisable.
- Ground water is a good place to start since
most reductive dechlorination sites are monitoring methane in ground water.
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Initial Thoughts
- Soil gas methane in the contaminant source
area exceeding 10% of the LEL or ground water exceeding 10 mg/L indicates the need to monitor methane in the direction of receptors.
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Initial thoughts
- If bioremediation is induced beneath a structure,
implement subslab methane monitoring and/or mitigation including the installation of a continuous gas monitor in the lower level of the structure if appropriate.
- Indoor air exceeding 25% of the LEL should result
in building evacuation until mitigation and a comprehensive methane monitoring plan are implemented.
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No NO Yes No Yes Yes No No No Yes Yes Yes
Initiate methane
- monitoring. Are
concentrations greater than 10% LEL at receptors? Mitigation and Possible Evacuation. Source Area Groundwater > 10,000ug/l or Soil Gas > 10% of LEL? Receptors
- r
Structures Present? Anaerobic conditions directly beneatha structure? <25% LEL at the Property Border? Done- Monitor Quarterly Done- Monitor Quarterly Done- Monitor Quarterly Mitigation and Possible Evacuation.
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FAQs
Why does the guidance refer to landfill guidance? Landfills are completely different.
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Landfills and remediation sites are the same regarding methane
- Electromotive potential (anaerobic) amenable to
methanogens.
- Place for methane to build to 5-10%.
- Ignition source.
- No time element. Methane does not have to be
generated for thirty years to be a hazard.
- Consider nested monitoring wells to gauge
attenuation.
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Landfills and remediation sites are different
Cleaners Landfill
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FAQs
- Contaminant concentrations aren’t that high
at my site. Do I need to worry about methane?
- Yes. It’s not the contaminant concentration
that matters. A methanogen’s energy source is not the contaminant, it is what you are injecting.
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FAQs
- What about Petroleum sites?
- Concentrations would be applicable. ITRC
guidance on ethanol fuels is listed in the references.
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FAQs
- What frequency should I monitor?
- Site-specific determination.
– Monthly
- Decrease frequency if lines of evidence indicate no
issue.
- Increase frequency if methane is an issue.
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Soluble Carbon Injections
Ground water mg/L Soil Gas %LEL %CH4 04/27/11 0.840 06/21/11 17 08/10/11 21 09/19/11 512 25.6 09/20/11 302 15.1
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Soluble Carbon Injections
Ground water mg/L Soil Gas %LEL %CH4 10/28/11 264 13.2 11/29/11 0.290 12/15/11 346 17.3
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Enhanced Reductive Dechlorination Injections Injection Depth: 20-32 ft bgs Injection Date: Aug 2007, June 2009, July 2013 Ground water at @20 ft bgs
MMW8S MMW1S 14-24 ft bgs 10-20 ft bgs ug/L ug/L 2/28/2013 12,000 54 5/14/2013 8,600 75 9/24/2013 25,000 24,700 11/13/2013 27,400 427 2/26/2014 22,100 162
ERD Injections
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FAQs
- What does intrinsically safe mean?
- Generally the electrical components are
housed so that the spark can’t get out or the casing is reinforced to withstand an explosion.
- National Electrical Code (NEC) and
Underwriters Laboratory (UL) define and rate.
- $$$
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FAQs
- I have methane above the explosive limit. Do I
need to come unglued?
- Maybe. Look at the complete conceptual
- model. Is there a place for the methane to
collect before it has attenuated? It’s hard to get the subsurface to explode. Watch for shallow ground water beneath structures.
- Know your site.
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References
- Eklund, B.; 2010; Proposed Regulatory Framework for Evaluating the Methane
Hazard due to Vapor Intrusion; presented at the AWMA Vapor Intrusion Conference; September 29-30, 2010, Chicago, IL; available online at: http://events.awma.org/education/vapor-proceed.html
- ITRC (Interstate Technology Regulatory Council); September 2011;: Biofuels:
Release Prevention, Environmental Behavior, and Remediation
http://www.itrcweb.org/guidancedocuments/biofuels/biofuels-1.pdf .
- Kean, Judy; Graves, Duane; Lodato, Mike; Enhanced Reductive Dechlorination
and the Relationship Between CIS-1,2-DCE Accumulation and
- Methanogenesis. Available online at:
http://www.drycleancoalition.org/download/enhanced_reductive_dechlor.pdf
- USGS. (2006). Methane in West Virginia Ground Water; USGS Fact Sheet 2006-
3011; available online at: http://pubs.usgs.gov/fs/2006/3011/pdf/Factsheet2006_3011.pdf
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