Monitoring Reclaimed Mine Land for Stray CO2 Hazards
Upcoming SlideShare
Loading in...5
×
 

Monitoring Reclaimed Mine Land for Stray CO2 Hazards

on

  • 688 views

Presented at Society for Mining, Metallurgy & Exploration (SME) 2012 Annual Meeting. This talk covered research done by a coorporative agreement with the US Office of Surface Mining, Reclamation & ...

Presented at Society for Mining, Metallurgy & Exploration (SME) 2012 Annual Meeting. This talk covered research done by a coorporative agreement with the US Office of Surface Mining, Reclamation & Enforcement.

Statistics

Views

Total Views
688
Views on SlideShare
433
Embed Views
255

Actions

Likes
0
Downloads
2
Comments
0

2 Embeds 255

http://sphinxminingsystems.com 253
http://webcache.googleusercontent.com 2

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Monitoring Reclaimed Mine Land for Stray CO2 Hazards Monitoring Reclaimed Mine Land for Stray CO2 Hazards Presentation Transcript

  • Monitoring Reclaimed MineLand For Stray CO2 Hazards Mathiba Moagabo Kwame Awuah-Offei 1
  • Outline• Background• Study sites• Sampling procedures• Data analysis• Results & discussions• Conclusions 2
  • BACKGROUND 3
  • Background• Elevated CO2 concentrations in homes is now being recognized as a safety & health hazard• Incidents of potentially lethal concentrations reported: – CO2 > 25% (MSHA action level = 0.5%) – O2 < 10% (MSHA a. l. = 19.5%)• Attributed to AMD-carbonate neutralization• Several cases reported in several parts of the Appalachia (OH, PA, WV, IN), UK, Canada.
  • Project ObjectiveTo develop a soil CO2 flux surveyprotocol for assessing reclaimed mineland, to determine the hazard potentialand to delineate, potentially, hazardousareas 5
  • STUDY SITES 6
  • Site 1: Hudson Site• Located in Pike Co., IN• Latitude: 38°19’ 2”• Longitude: 87°08’ 27”• Coal mined from 1986 to 1992• Spoil material extends to ~11.6 m below• ~36 ha Reclaimed with lime amendment and about 0.91 m of top soil capping• Episodes of elevated concentrations of stray CO2 since 2006 7
  • Site 2: Godin Site• Located in Sommerset Co., PA• Latitude: 40°08′ 02″• Longitude: 79°02′ 52″• Home built on 70 ft thick, reclaimed mine spoil• Permit required spoiling pit cleanings in pods >10 ft above pit floor with 20 tons/acre of lime amendment• CO2 intrusions into home reported in 2003 8
  • SAMPLING PROCEDURES 9
  • Flux Sampling• LI-8100 automated flux system• Collars installed for >24 hrs• Each sampling point surveyed• Chamber deployed for 2 minutes 10
  • 11
  • Isotope Sampling • Method 1 – Grab samples from 2 ft deep slam bars and bore holes • Method 2 – Multiple (3) gas samples drawn during chamber deployment – Method accounts for isotope fractionation and gas mixing 12
  • DATA ANALYSIS 13
  • Tests of Correlation• Pearson correlation coefficients used to assess correlation• Moran’s I statistic used to assess spatial correlation• Significance of correlations assessed at 95% confidence n n n I wij Z si Z Z sj Z n 1 S 2 w.. i 1 j 1 n 2 Z si Z S2 i 1 n 1 14
  • Geostatistical Analysis• Included variogram modeling, estimation, and probability maps using sequential Gaussian simulation (sGs)• We used GS+ version 9• Spherical variogram model selected• 1,000 simulations (sGs) 15
  • RESULTS & DISCUSSIONS 16
  • Preliminary Statistics SAMPLE DAYParameter March 30, 2010 March 31, 2010 April 1, 2010Anderson- A2 7.15 0.29 7.27 0.49 6.44 0.70Darling p-valueNormality Test < 0.005 0.600 < 0.005 0.216 < 0.005 0.064Mean 2.345 0.269 2.512 0.330 2.960 0.401Standard Deviation 1.820 0.294 1.676 0.238 1.806 0.236Variance 3.313 0.086 2.809 0.056 3.262 0.056Skewness 2.167 0.187 2.355 0.493 2.095 -0.078Kurtosis 5.695 -0.175 7.077 0.147 5.539 1.540Number of Samples, N 131 131 131 131 130 130 17
  • Preliminary Statistics SAMPLE DAYParameter July 13 2010 July 14 2010 July 16 2010Anderson- A2 1.57 0.88 0.68 1.89 0.63 0.26Darling p-Normality value <Test 0.0005 0.023 0.071 < 0.005 0.099 0.700Mean 5.029 0.664 8.859 2.132 7.878 2.00Standard Deviation 2.264 0.186 3.049 0.400 2.716 0.3539Variance 5.123 0.0345 9.295 0.160 7.374 0.1252Skewness 2.472 -0.4098 0.0934 -2.330 0.584 -0.2614Kurtosis 12.627 1.6950 1.428 11.439 -0.008 -0.1342Number ofSamples, N 71 71 73 72 71 71 18
  • Correlation AnalysisDay Correlated Variable Soil temp. Soil moistureMarch 30 Log of Flux 0.521 -0.402 p-value < 0.0001 <0.0001March 31 Log of Flux 0.280 -0.106 p-value 0.001 0.230April 1 Log flux 0.263 -0.325 p-value 0.002 < 0.0001 19
  • Spatial DependenceData Set No of Global Moran’s Expected Value p-value Samples IPike Co. Day 136 0.4284 -0.0074 0.00001Pike Co. Day 136 0.3190 -0.0074 0.00002Pike Co. Day 132 0.2666 -0.0076 0.00003Godin Day 1 71 -0.0404 -0.0143 0.6219Godin Day 2 71 0.1074 -0.0143 0.0755Godin Day 3 71 0.1535 -0.0143 0.0242 20
  • Isotope Tests Depth (m) 0 0.61 5.79 11.58 0 -10δ13C-CO2 ( ‰) -20 -30 -40 21
  • Estimation 22
  • Conclusions• Soil temperature and moisture content are important factors that influence soil gas emission• Spatial dependence should not be assumed, but must be evaluated for each site• The spatial variability in soil CO2 emissions appears to be controlled by gas permeability and macro-porosity• This project has developed a soil CO2 flux survey protocol 23