Response Protocol for Large Underground Methane Emissions (R-PLUME)


Summary:

Project Title: Validating Models for Predicting Gas Migration and Mitigating its Occurrence/Consequence

Colorado State University and the Southern Methodist University (SMU) are working on a major project to better understand gas migration from moderate-to-large underground leaks, validating models to understand those leaks, and developing methods to assess and respond to these leaks.  Underground natural gas pipeline leakage, especially at moderate to high flow rates, can result in gas migration and buildup, producing explosive concentrations within nearby substructures. A critical knowledge gap is knowing how environmental conditions affect gas migration behavior in these scenarios, and how emergency first responders can factor them into decision making. As part of the project, we review historical incident reports from PHMSA and identify if conclusions drawn from our field measurements could have prevented the incident. This project addresses PHMSA’s request for high resolution field tests for model validation by using novel above/below ground sensors to characterize gas migration speed and distance at high leakage rates and concentrations above explosive limits. This work will:

  • Advance methods to characterize significant natural gas leaks from buried pipelines,
  • Advance leak detection and repair methods for pipeline leaks, especially large leak scenarios,
  • Deliver an empirical understanding of large leak behavior that can be incorporated into first responder and leak detection protocols.

Colorado State University and the Southern Methodist University are collaborating with industry and first responder partners, who serve as members on a technical advisory panel, provide access to their response protocols, and, in some cases, participate in field testing. Controlled field testing is performed at CSU’s Methane Emission Technology Evaluation Center. 

Objectives:

The project will focus on underground natural gas (NG) leaks with moderate to high flow rates (>100 scfh) that can produce explosive concentrations nearby.  Proposed work will advance the understanding of gas migration behavior and provide decision guidance for stakeholders by:

  1. Making direct measurements of gas migration speed and extent at the surface, and in the subsurface, in a range of environmental conditions.
  2. Pairing measurements with models to extend knowledge beyond measurable scenarios.
  3. Linking gas concentration measurements with observations of environmental conditions to estimate extent a
Aerial view of METEC test beds, with R-PLUME Testbed labeled. The R-PLUME Rural test bed is in the southwest corner. The R-PLUME urban test beds are in the south east corner, with House 1, 2, and 3 labeled.

Project Plan:

  1. Determine collaborative study structure. Results due to PHMSA within three (3) months of the effective date of the Agreement.
  2. Survey existing first responders’ operational practices. Summary of current RPs from TAP members and other contributors. Guidance for improving RPs for large leak rates and transient gas migration events. Results due to PHMSA within seven (7) months of the effective date of the Agreement.
  3. Methods for estimating gas migration and leak size from readily obtained measurements at a leak event. Results due to PHMSA within nine (9) months of the effective date of the Agreement.
  4. Test bed completion. Results due to PHMSA within nine (9) months of the effective date of the agreement.
  5. Sampling points installed. Results due to PHMSA within twelve (12) months of the effective date of the Agreement.
  6. Report on a practical approach to the design, operation and monitoring of natural gas soil venting systems. Results due to PHMSA within fourteen (14) months of the effective date of the agreement.
  7. Comprehensive experimental data sets from METEC test site. Results due to PHMSA within nineteen (19) months of the effective date of the Agreement.
  8. Report on understanding of the degree to which parameters affect the subsurface natural gas migration with significant flow rates. Results due to PHMSA within twenty-two (22) months of the effective date of the Agreement.
  9. Understanding how variability in gas composition affects the subsurface natural gas migration with significant flow rates. Results due to PHMSA within twenty-eight (28) months of the effective date of the Agreement.
  10. Test bed/installation points completion at TTC. Results due to PHMSA within sixteen (16) months of the effective date of the Agreement.
  11. Comprehensive experimental data sets from TTC test site. Results due to PHMSA within twenty-two (22) months of the effective date of the Agreement.
  12. Analysis of field data. Understanding how variability in parameters affect the subsurface natural gas migration with significant flow rates. Results due to PHMSA within twenty-three (23) months of the effective date of the Agreement.
  13. Initial modelling tool to predict behavior of underground leaks with significant flow rates. Results due to PHMSA within twenty-five (25) months of the effective date of the Agreement.
  14. Initial report on understanding how gas composition and environmental variability affects the subsurface natural gas migration with significant flow rates. Results due to PHMSA within forty (40) months of the effective date of the Agreement.
  15. Report how a better understanding of gas migrations rate informs first responders’ protocol – Urban/rural differences. Submit a draft of clear, concise recommendations to be submitted to the appropriate organizations for incorporation into the relevant consensus guides, standards, and recommended practices manuals. Results due to PHMSA within forty-one (41) months of the effective date of the Agreement.
  16. Final report. Set of clear, concise recommendations to be submitted to the appropriate organizations for incorporation into the relevant consensus guides, standards, and recommended practices manuals. Results due to PHMSA within forty-four (44) months of the effective date of the Agreement.
  17. completion of all documentation. QC/QA and curation of data. Peer-reviewed papers on measurement methods and behavior of underground leaks with significant flow rates. Results due to PHMSA forty-eight (48) months of the effective date if the agreement
  18. Quarterly status and progress reports and final project report will be prepared and submitted in accordance with the Basic Agreement. Completed within forty-eight (48) months.

Funding Provided by:

Pipeline and Hazardous Materials Safety Administration

Colorado Oil & Gas Conservation Commission

View the project award here. Contract ID: 693JK32010011POTA. Proposal title is: Validating Models for Predicting Gas Migration and Mitigating its Occurrence/Consequence

Collaborators

  • University of Texas – Arlington
  • Southern Methodist University (SMU)
  • Fort Lewis College
  • White Plains Fire Department
  • Poudre Fire Authority
  • Western Metro Fire Department
  • Western Midstream
  • Con Edison
  • Southern California Gas company
  • Pacific Gas and Electric Company
  • Pipeline and Hazardous Materials Safety Administration
  • Colorado Oil & Gas Conservation Commission

Document Links:

Pipeline and Hazardous Materials Safety Administration (dot.gov)

COGCC Home (state.co.us)

Fire Fighter | White Plains, NY – Official Website (cityofwhiteplains.com)

Poudre Fire Authority | Home (poudre-fire.org)

West Metro Fire Protection District, CO | Official Website

Home (westernmidstream.com)

Con Edison – Powering New York City and Westchester

Home | SoCalGas

PG&E, Pacific Gas and Electric – Gas and power company for California

R-PLUME Schedule

ActivityTaskTask NameDurationStartFinish
1Kick-off meeting1 dayThurs 10/28/20Thurs 10/28/20
21Establish a collaborative structure8 weeksWed 09/30/20Tue 12/01/20
32Survey first responder RPs16 weeksMon 11/02/20Fri 03/12/21
43.1Sensor bench/in-ground testing - Analyze existing leak methods and identify ways to improve32 weeksWed 09/30/20Wed 06/02/21
53.2aModify test bed at for gas flows up to 600 SCFH32 weeksWed 09/30/20Wed 06/02/21
63.2bInstall additional emission points/rates and sampling methods into amended test bed13 weeksThur 06/03/21Wed 09/08/21
73.3Document method in project reports/journal article8 weeksThur 09/09/21Wed 11/03/21
84.1METEC tests - Measure gas migration rates in a range of conditions, 20 tests26 weeksThur 09/09/21Mon 03/28/22
94.2Test summary/reporting 12 weeksTue 03/29/22Mon 06/20/22
104.3Follow-up experiments - Wet gas, PDFA Hazmat, QC/QA data20 weeksTue 08/16/22Mon 01/02/23
115.1TTC - Install test bed and emission points6 weeksThur 11/04/21Mon 01/03/22
125.2TTC Experiments - Varying depth and environmental conditions8 weeksTues 04/26/22Mon 06/20/22
135.3Test summary/reporting 4 weeksTue 06/21/22Mon 07/18/22
146Extend results via modeling Numerical simulations49 weeksFri 07/19/22Fri 06/30/23
157.1Initial guidance draft4 weeksMon 07/03/23Mon 07/31/23
167.2Guidance revision 8 weeksTues 08/01/23Fri 09/29/23
178.1Final guidance dob - wrap up reporting for the project, including journal publications4 weeksMon 10/02/23Tues 10/31/24
188.2Final reporting 13 weeksWed 11/01/23Wed 01/31/24
19Quarterly team meetingsAs scheduled
20Prepare and submit quarterlyAs required
21Final Team Meeting1 dayWed 01/31/24Wed 01/31/24

Accomplishments/Results:

Task 4.1, METEC Tests Field-based methane release experiments are continuing at the METEC Urban testbed to determine subsurface expansion of gas transport from mid to large emissions in urban/suburban environments in accordance with the approved experimental plan. Continuing experiments investigate the effects of changing the surface covers (Experiment set 2: Surface cover). More than 24 tests have been completed (Table 2).

Table 2 Summary of all experiments conducted to date. All subsurface emissions were released at 0.9 m below ground level for 24 hours.

*Indicates experiments with simulated heavy rain fall
Experiment NumberExperiment DateTime of leak startEmission rate (slpm)CoveringSub-surfaceSoil Moisture (%)Variable
111/11/202110:3610GrassSoil25Leak rate
211/11/20219:5010GrassSoil25Leak rate
312/3/202111:0035GrassSoil25Leak rate
412/1/202112:5035AsphaltPipes25Leak rate
511/15/202110:4350GrassSoil25Leak rate
611/19/202110:5550AsphaltPipes25Leak rate
73/25/202211:0910GrassSoil40Soil moisture
83/23/202212:2510AsphaltPipes40Soil moisture
94/5/20229:1135GrassSoil40Soil moisture
103/30/202210:4235AsphaltPipes40Soil moisture
112/17/20226:3310SnowSoil25Covering
122/23/20228:2010SnowPipes25Covering
133/2/20228:3810SlushPipes25Covering
143/7/202211:0210SlushPipes25Covering
1512/8/202110:2810FrostSoil25Covering
1612/13/202112:1235FrostSoil25Covering
176/21/20229:0010SemiSoil25Covering
186/21/20229:0010SemiSoil25Covering
194/21/20229:5410AsphaltOpen25Subsurface
204/11/202212:4635AsphaltOpen25Subsurface
215/2/202213:4310GrassSoil40Soil moisture*
225/4/202211:0510AsphaltPipes40Soil moisture*
236/20/20229:00100GrassSoil25Leak rate
246/27/20229:00150GrassSoil25Leak rate

Task 6, Numerical Simulations

To union with experimental understanding, numerical simulations were performed using computational models to guide observations and interpret data. The numerical simulations were performed using the multiphase transport simulator COMSOL 6.1. models simulated transport of aqueous and gas phases containing multi-components under non-isothermal conditions. Using the numerical model, various parameter combinations beyond experimentally measurable scenarios were created to deliver an empirical understanding.

Table 3: Summary of all numerical simulations conducted to date. All simulations were conducted considering a leak at 0.9m below ground level.
Leak rate20 scfh (10 slpm) - Base case characteristic
1 scfh (0.5 slpm)
70 scfh (35 slpm)
Gas CompositionsMethane 85%, Air 15% - Base case characteristic
Methane 70%, Ethane 30%
Methane 70%, Ethane 20%, Propane 10%
Methane 70%, Ethane 10%, Propane 10%, Butane 10%
Soil TypeLoam - Base case characteristic
Sand
clay
Soil MoistureLoam - with a saturated topsoil layer
Sand - with a saturated topsoil layer
Clay - with a saturated topsoil layer
Surface conditionsUncovered - Base case characteristic
Snow cover
Asphalt cover
Saturated soil
Subsurface complexicyBuried pipelines
Disturbed soil (trench)
Combined subsurface complexities and surface conditionsLoam soil with Trench and Pipe
Loam soil with Trench, Pipe, and Asphalt cover
Loam soil with Trench, Pipe, and Snow cover
Loam soil with Trench, Pipe, and Moist topsoil
Loam soil with Trench, Pipe, Asphalt and Snow cover
Loam soil with Trench, Pipe, Asphalt and Moist topsoil

CSU and SMU have made significant progress on this project. See the Final Report below.

RPLUME Final Report Briefing to PHMSA – May 2024

Peer Reviewed Publications

  1. Tian, S., S.N. Riddick, Y. Cho*, C.S. Bell, D.J. Zimmerle, K.M Smits. 2022. Investigating detection probability of mobile survey solutions for natural gas pipeline leaks under different atmospheric conditions. Environmental Pollution. https://doi.org/10.1016/j.envpol.2022.120027
  2. Cho, Y.*, K.M. Smits, N.L. Steadman, B.A.Ulrich*, C.S.Bell, D.J. Zimmerle, 2022, A closer look at underground natural gas pipeline leaks across the United States, Elementa: Science of the Anthropocene,https://doi.org/10.1525/elementa.2021.00095
  3. Tian, S., K.M. Smits, Y. Cho*, S.N. Riddick, D.J. Zimmerle, A. Duggan. 2022. Estimating methane emissions from underground natural gas pipelines using an atmospheric dispersion-basedmethod. Elem Sci Anthrhttps://doi.org/10.1525/elementa.2022.00045
  4. R.R.N, R.S. KolodziejIV, S.N. Riddick, D. Zimmerle, and K.M. Smits. 2023. Influence of Soil-Gas Diffusivity on Expansion of leaked Underground Natural Gas Plumes and Application on Simulation efforts. J. of Hydrology, Accepted for Publication
  5. Cheptonui, F., S.N. Riddick, S. Tian, J.R.R.N. Jayarathne, M. Mbua, K.M. Smits, D.J. Zimmerle. 2022. Estimating the sub-surface leak rate of a Natural Gas pipeline using above-ground downwind measurements: The ESCAPE-1 MODEL. In review
  6. Tian, S., S.N. Riddick, M. Mbua, Y. Cho*, D.J. Zimmerle, K.M. Smits. 2022. Improving the efficacy of leak survey methods using 3D plume measurements. In review
  7. Mbua, M., S.N. Riddick, T. Shanru, F. Cheptonui, H. Cade, Y. Cho, K.M. Smits and D.J. Zimmerle. 2023. Using controlled subsurface releases to investigate the effect of leak variation on above-ground natural gas detection.In review
  8. Lo, J., K.M. Smits, Y. Cho, J. Duggan, S. Riddick,Quantifying Non-steady State Natural Gas Leakage from the Pipelines Using an Innovative Sensor Network and Model for Subsurface Emissions -InSENSE, Journal of Gas Scienceand Engineering, In review
  9. Riddick, S. N., Cheptonui, F., Tian, S., Jayarathne, J. R. R. N., Mbua, M., Smits, K. M. and Zimmerle, D. J.Reconciling above and below ground methane concentration measurements for subsurface emissions of wet and dry natural gas. In preparation.
  10. Jayarathne, J. R. R. N., R. S.Kolodziej, S. N. Riddick, D. J.Zimmerle, and K. M. Smits. 2022. Effect of Soil Surface Conditions on Belowground Migration and Plume Development of Natural Gas Leaked from Underground Pipelines. To be submitted to Environmental Science and Technology Letters.In preparation

Invention Disclosure

  1. Cho, Y., G.P. Duggan, D.J. Zimmerle, S. Riddick and K.M. Smits,Monitoring and detection network, deployment methods and quantification for anthropogenic greenhouse gas emissions from belowground sources, submitted 5/12/23

METEC Research Alert Publications & Conference Proceedings

  1. Jayarathne, J. R. R. N., R. S.KolodziejIV, S. N. Riddick, D. J.Zimmerle, and K. M. Smits. 2022. For Leaks in Snow and Ice Conditions, Experiments Show Faster Gas Migration, Higher Gas Concentrations, and Continued Gas Migrations Days after Leak Was Stopped.METEC Research Alert, April 5, 2022.
  2. Jayarathne, J. R. R. N., R. S.KolodziejIV, S. N. Riddick, D. J.Zimmerle, and K. M. Smits. 2022.For Leaks in Rain, Snow, and Ice Conditions, Experiments Show Faster Gas Migration, Higher Gas Concentrations, and Continued Gas Migrations Days after Leak Was Stopped.METEC Research Alert, Sept 9, 2022.
  3. Jayarathne, J. R. R. Navodi, K.M. Smits, S.N. Riddick, D. J. Zimmerle, Y. Cho, M. Schwartz, F. Cheptonui, K. Cameron, P. Ronney, 2022, Understanding Mid-to Large Underground Leaks from Buried Pipelines as Affected by Soil and Atmospheric Conditions –Field Scale Experimental Study. Proceedings from the Pipeline Research Council International (PRCI) REX2022 Meeting. (presentation and proceedings)

Presentations and Posters

  1. Smits, K.M., GHG Reduction Opportunities through Detection and Quantification of Belowground Natural Gas Pipeline Leaks, Texas Society of Professional Engineers (TSPE) Annual Meeting, Dallas TX, May 11, 2023, Invited presentation.
  2. Smits, K.M., GHG Reduction Opportunities through Detection and Quantification of Belowground Natural Gas Pipeline Leaks, PHMSA’s Accident Investigation Division Meeting, Washington, D.C., April 25, 2023, Invited presentation.
  3. R.R.N, R.S KolodziejIV, Y. Cho, S.N. Riddick, D.J. Zimmerle, and K.M. Smits. 2022. Unraveling Natural Gas Migration Rate and Extent from Leaking Underground Pipelines under Varying Environmental Conditions. 2022 AGU Fall Meeting, 12 -16 December 2022, Chicago, Illinois. (poster)
  4. Jayarathne J.R.R.N, R.S. Kolodziej IV, Y. Cho, S.N. Riddick, D.J. Zimmerle, and K.M. Smits. 2022.Unraveling Natural Gas Migration Rate and Extent from Leaking Underground Pipelines under Varying Environmental Conditions. Improving the efficacy of leak survey methods using 3D plume measurements. Then in the annual CH4Connectionsconference, October 20-21, 2022, Fort Collins, Colorado.(poster)
  5. Tian, S., S.N. Riddick, M. Mbua, Y. Cho, D.J. Zimmerle, K.M. Smits. 2022. Improving the efficacy of leak survey methods using 3D plume measurements. 2022 AGU Fall Meeting, 12 -16 December 2022, Chicago, Illinois. (poster)
  6. Lo, K.M. Smits, Y. Cho, J. Duggan, S. Riddick, Utilizing the Near Real-Time Methane Detector Network to Study and Quantify Underground Natural Gas Leakage from the Pipeline, CH4 Connections conference, Oct 20-21, 2022 (poster)
  7. Mbua, M., S.N. Riddick, S. Tian, , F. Cheptonui, H. Cade, Y. Cho, K.M. Smits, and D.J. Zimmerle. 2022 Using controlled subsurface leak experiments to improve leak detection solutions’ protocol. The ninth annual CH4 Connections conference, October 20-21, 2022, Fort Collins, Colorado. (poster)
  8. Lo, J.,K.M. Smits, Y. Cho, J. Duggan, S. Riddick, Utilizing the Near Real-Time Methane Detector Network to Study and Quantify Underground Natural Gas Leakage from the Pipeline, American Geophysical Union Fall Meeting, Dec 2022 (poster)
  9. Tian, S., S.N. Riddick, M. Mbua, Y. Cho, D.J. Zimmerle, K.M. Smits. 2022. Improving the efficacy of leak survey methods using 3D plume measurements. The ninth annual CH4 Connections conference, October 20-21, 2022, Fort Collins, Colorado. (poster)
  10. Cho,Y., J. H. Lee , J. Lo , J. Duggan , K. M. Smits, and D. Zimmerle. “Natural gas fugitive leak detection and quantification using a continuous methane emission monitoring system and a simplified model” AGU 2022 Fall meeting (poster)

Opportunities:

This project is completed.  However, there are several ways to get engaged in other similar or future projects.  Please email [email protected]