Land use planning for industrial development requires estimation of the environmental impacts associated with a given land use choice. For underground coal mining, there are a number of surface environmental impacts resulting from the underground mining activities. AECOM, in a project for the U.S. Bureau of Land Management, developed an emission inventory estimation tool to allow estimation of air emissions from proposed underground coal mines in the Western United States. This presentation provides a summary of the emission inventory tool for underground coal mines that AECOM developed in fulfillment of this project.

1. Underground Coal Mine
Emission Inventory Tool
Howard W. Balentine, CCM, P.E.

2. About AECOM
AECOM is a global provider of professional technical and
management support services to a broad range of
markets, including
transportation, facilities, environmental, energy, water and
government. With approximately 45,000 employees around
the world, AECOM is a leader in all of the key markets that it
serves. AECOM provides a blend of global reach, local
knowledge, innovation and technical excellence in delivering
solutions that create, enhance and sustain the world’s
built, natural and social environments. A Fortune 500
company, AECOM serves clients in more than 140 countries
and has annual revenue in excess of $8.0 billion.
More information on AECOM and its services can be found
at www.aecom.com.

3. Design Objectives for Emission Inventory Tool
– Develop a methodology to estimate air pollutant
emissions associated with Western underground coal
mining
– Allow estimates for historical and current operations
– Provide means to project emissions from future proposed
mining operations
– Allow emission estimates for mining operations with
limited data

4. How AECOM Met Study Objectives
– Developed Emission Tool using Microsoft Excel
– Estimates emissions of Criteria Pollutants, Greenhouse
Gases (GHGs), and Diesel Particulate Matter (DPM)
– Establishes standard default parameters with ability to
override
– Multiple calculation options with increasing mine-specific
data requirements for certain source categories
– Quality Assurance (QA), including listing of all default
parameters and color coding of required entries
– Complete documentation of computation methodology
and supporting data

5. Sources of Emissions Inventoried in the Tool
Emission Source Pollutants Inventoried Sources Included
Degasification wells Methane & CO2 Degasification well vents
Mine ventilation
Methane & CO2
PM10 and PM2.5
Mine ventilation system exhaust
Underground
equipment
Criteria, GHGs & Diesel
Particulate
MSHA certified underground
equipment and non-road vehicles
Aboveground
equipment
Criteria, GHGs & Diesel
Particulate
Mobile and stationary equipment and
non-road vehicles
Coal Haul Locomotives
Criteria, GHGs & Diesel
Particulate
Coal haul locomotives
Aboveground material
handling
PM10 and PM2.5
Fugitive dust from handling and
processing coal and rock
Disturbed area fugitive
dust
PM10 and PM2.5 Windblown dust from exposed areas
Paved and Unpaved
Roads
PM10 and PM2.5 Vehicle traffic

6. Estimating GHG Emissions
– EPA has a well established methodology for particulate
matter emission inventory development for Western
surface mining
– Previous GHG emission inventory efforts have been site
specific or depend on monitoring data
– The methodology developed for estimating methane
emissions from underground mining is innovative

7. Source of Methane in a Coal Mine
– Methane is created along with
coal
– Under increasing pressure from
overburden accumulation,
methane adsorbs onto the coal
– Amount of coal absorbed
is primarily a function of
the pressure
– Upon release of pressure
during mining, the
methane desorbs from
the coal

8. Most Underground Mining in Colorado Involves
Longwall Mining
Photo Source: BLM, Ucompahgre Field Office Coal Resource and Development
Potential Report ,April 2010.

9. Section of a Longwall Mining Machine

10. Longwall Mining Layout

11. Methane is released from degasification wells
and ventilation exhaust
– Pre-mining degasing
– Degasing during mining
– Mine Ventilation
– Post-mining degasing
– Post-mine closure/abandonment

12. Methane Adsorption Curve for Western Coal
Absorption curve computed based on a pressure gradient of 0.435 pounds per square foot per foot of increasing
depth, fitted to a Michaelis-Menten distribution.
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400
GasContent(scf/ton)
500
Pressure (psia)
Methane
Adsorption
M-M Trend

13. Mine Ventilation Rate versus Coal Production —
Western Underground Coal Mines
Data Sources: EPA, 2010; Colorado Department of Health, 2012

14. Greenhouse Gas Emission Estimation
– Emissions are a complex function of mine depth, coal
seam and coal basin characteristics, and mining methods
– Objective was to produce a simplified methodology
– Three calculation methods allowed for estimation of
desorption methane
• Coal production tonnage, seam depth, and adsorption curve
• Emission factors by state, coal basin, and drainage/degasification
system based on published EPA data, and
• Mine-specific information on methane releases

15. Particulate Matter Emissions from Disturbed
Areas
– EPA emission estimation requires daily maximum daily
wind speed
– Modeled a Log-Normal distribution for 3 years of data for
use in computation of daily friction velocity
(friction velocity is required in computation of wind blown dust emissions)
– Wind data included :
• Aspen
• Gunnison
• Grand Junction

16. Prospective Tool Uses
– Establish a consistent methodology to inventory emissions
from Western underground coal mines
– Provide input to Program Level National Environmental
Policy Act analyses
– Assess emissions for new mining lease applications
– Provide estimates of GHG emissions for climate change
and adaptation analyses
– Assess toxic risks from diesel particulate matter emissions
from underground coal mines and locomotives

17. Potential Area of Improvement
– Extensive information on methane emissions from
underground coal mines is being reported to EPA yearly
under 40 CFR 98 Subpart FF
– This data include methane concentrations and flow
volumes in degasification and ventilation systems
– Combined with information on mined formation, coal
basin, and mining depth, the EPA data could be
processed and incorporated into this tool
– The revised tool would allow more refined estimates of
GHG emissions for historical and future mining operations

18. Acknowledgements to AECOM’s project team
̶ Howard Balentine, Project Manager
̶ Sameer Shah
̶ Gregory Derevianko
̶ Snigdha Mehta
̶ Anne Doud
̶ Courtney Taylor

19. Howard W. Balentine, CCM, P.E.
Howard W. Balentine is a technical leader with more than 35
years of experience in environmental services. His areas of
expertise include climate change analysis, greenhouse
gas/carbon footprint assessment and verification, emission
inventory development, environmental engineering and air
pollution meteorology.
howard.balentine@aecom.com