Soil changes during stockpiling and after reclamation at three Wyoming natural gas production areas Jay Norton and Calvin Strom University of Wyoming 2017 Joint Conference of the American Society of Mining and Reclamation Mine Drainage Task Force Appalachian Regional Reforestation Initiative Morgantown, West Virginia April 12, 2017
Soil Function in aridisols and aridic alfisols • A horizon: interface with atmosphere: – OM accumulation and ELUVIATION; – loss of clays, solutes; – More OM, coarser texture, lower EC & pH than other horizons; – Water infiltration & holding; nutrient cycling (microbes) – Germination/establishment ; • B horizon: zone of accumulation of clays and solutes: ILLUVIATION – Less OM, finer texture, higher EC & pH – Water holding in finer texture
Salvage & reclamation procedures One size fits all
Pre disturbance: ABSTON FINE, SMECTITIC, FRIGID USTIC NATRARGIDS A sandy loam E Bt clay Scraping depth Btn1 Btn2 Bk Cr
After reclamation: ENTISOL Clay loam Clay loam Topsoil Subsoil
Loss of A horizon reduces already slim chances for germination & establishment • Lifeless: little SOM to support microbial activity and nutrient cycling; • Finer: inhibits water infiltration and facilitates evaporation; • Drier: less OM and fine texture decrease plant-available water; • Saline: EC > 4; osmotic potential and ion toxicity slow germination; • Sodic: ESP > 15 disperses aggregates, exacerbating the above.
Pipelines + P&A + Active wells 29,683 Currently Producing Wells On File 121,626 Total Wells On File (DrillingEdge.com)
Great Divide and Green River Basins Objectives: determine short and longer-term effects of natural gas development and reclamation on soil quality across a precipitation gradient. Effects of topsoil depth on organic matter dynamics Aridisols and Entisols formed in saline and sodic marine shales. 11 inches 9 inches 7 inches
Soil Organic Matter Pools LOSSES: Harvest, CO 2 Active, or labile, SOM: & N 2 O emissions, Annual turnover STRUCTURAL erosion etc. SOM Mineral N Mineralizable C& N PLANT RESIDUE METABOLIC dissolved organic C & N; SOM Microbial C & N; ACTIVE light fraction C & N. ACTIVE SOIL SOM C Slow, or protected, SOM: Decades; Same as labile, but SLOW protected from SOIL mineralization within soil Slow C structure. SOM Passive, or stabile, SOM: PASSIVE Centuries to millennia; SOM Humus; Mineral-associated C & N;
Pinedale Anticline Elevation: 2440 meters MATmax: 11°C MATmin: -6.6°C Fine-loamy, mixed, superactive, frigid Calcidic Haplustalfs MAP: 276 mm Annual CV: 26.5% 70 30 60 20 Precipitation (mm) Temperature (C) 50 10 40 0 30 -10 20 -20 10 0 -30 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Jonah Field Elevation: 2140 meters MATmax: 11.9 ° C MATmin: -7.2 ° C Fine-loamy, mixed, superactive, frigid Calcidic Haplustalfs MAP: 232 mm Ann CV: 27% 60 30 Total Precipitation Max. Temperature 50 20 Precipitation (mm) Min. Temperature Temperature (C) 40 10 30 0 20 -10 10 -20 0 -30 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Wamsutter/Great Divide Basin Elevation: 2065 meters MATmax: 13.2 ° C MATmin: -2.6 ° C Fine-loamy, mixed, superactive, frigid Typic Haplargids MAP: 180 mm Ann CV: 32% 60 30 50 20 Precipitation (mm) Temperature (C) 40 10 30 0 20 -10 10 -20 0 -30 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Three new well pads sampled at each field starting in 2009 (9 points composited) 1. Predisturbance; 2. Stockpile; 3. Respread; 4. 1 year later; 5. 7 years later.
Soil samples from 0-5, 5-20, and 20-30 cm Stockpiles: Three points sampled to 250 cm
Data Collection • Vegetation cover • Physical properties: bulk density, texture • Chemical properties: pH, EC • Biological properties (total and labile soil organic matter): – Total soil organic carbon and nitrogen; – Mineral nitrogen; – Dissolved organic carbon and nitrogen; – Mineralizable organic carbon and nitrogen.
Jonah, 2011 Jonah, 2016
Anticline, 2011 Anticline, 2016
Study Period Precipitation Pinedale Jonah Wamsutter 450 400 Precipitation (mm) 350 300 250 200 150 100 50 0 2009 2010 2011 2012 2013 2014 2015 2016 2009 2010 2011 2012 2013 2014 2015 2016 2009 2010 2011 2012 2013 2014 2015 2016 Sep-Nov Sep-Nov Sep-Nov 160 140 120 100 80 60 40 20 0 2009 2010 2011 2012 2013 2014 2015 2016 2009 2010 2011 2012 2013 2014 2015 2016 2009 2010 2011 2012 2013 2014 2015 2016
Mineralizable C in stockpiles, 2009 Pinedale Jonah Wamsutter CO 2 -C mineralized (mg kg -1 ) CO 2 -C mineralized (mg kg -1 ) CO 2 -C mineralized (mg kg -1 ) 0 100 200 300 400 500 0 100 200 300 400 500 0 200 400 600 800 0 0 0 May 50 50 50 June August 100 100 100 Depth (cm) Depth (cm) Depth (cm) 150 150 150 200 200 200 250 250 250
Reclaimed: Soil texture Anticline Anticline Jonah Jonah Wamsutter Wamsutter Clay Content (%) Clay Content (%) Clay Content (%) Clay Content (%) Clay Content (%) Clay Content (%) 0 0 10 10 20 20 30 30 0 0 10 10 20 20 30 30 0 0 10 10 20 20 30 30 0 0 0 0 0 0 5 5 5 5 5 5 10 10 10 10 10 10 Depth (cm) Depth (cm) 15 15 15 15 15 15 20 20 20 20 20 20 25 25 25 25 25 25 30 30 30 30 30 30 35 35 35 35 35 35 Reclaimed Undisturbed Undisturbed
Reclaimed: Soil texture Anticline Jonah Wamsutter Clay Content (%) Clay Content (%) Clay Content (%) 0 10 20 30 0 10 20 30 0 10 20 30 0 0 0 5 5 5 10 10 10 Depth (cm) 15 15 15 20 20 20 25 25 25 30 30 30 35 35 35 Reclaimed Undisturbed
30 300 Jonah Mineral N Disturbance Effects PMN PMN and Mineral N (mg kg -1 ) 25 250 PMC 1. Undisturbed: high labile SOM concentrations, low mineral N concentrations (low net mineralization); 20 200 PMC (mg kg -1 ) 2. Pulse of labile and mineral nutrients after 15 150 disturbance truncated in cold storage in stockpile; 3. Pulse of mineralization at expense of PMC and N; 10 100 4. Loss of mineral N, labile OM begins to rebound. 5 50 0 0 Predisturbance Stockpiled Reclaimed Reclaimed 1 yr 0-30 cm weighted averages
30 300 60 600 Anticline Jonah Mineral N PMN PMN and Mineral N (mg kg -1 ) PMN and Mineral N (mg kg -1 ) 25 250 50 500 PMC 20 200 40 400 PMC (mg kg -1 ) PMC (mg kg -1 ) 30 300 15 150 20 200 10 100 10 100 5 50 0 0 0 0 Predisturbance Stockpiled Reclaimed Reclaimed 1 yr Predisturbance Stockpiled Reclaimed Reclaimed 1 yr 50 500 Wamsutter 45 450 PMN and Mineral N (mg kg -1 ) 40 400 Anticline: complicated by Disturbance Effects 35 350 stockpile being moved at PMC (mg kg -1 ) 30 300 least twice. 25 250 0-30 cm weighted 20 200 averages 15 150 10 100 5 50 0 0 Predisturbance Stockpiled Reclaimed Reclaimed 1 yr
Loss of labile C and N 250 25 500 50 Anticline PMC and N (mg kg -1 ) 200 20 Jonah 400 40 PMC and N (mg kg -1 ) 150 15 300 30 100 10 200 20 100 10 50 5 0 0 0 0 35 250 50 PMC and N (mg kg -1 ) Mineral Nitrogen (mg kg -1 ) Wamsutter 45 30 200 40 25 All Well Fields 35 150 30 20 25 15 100 20 15 10 50 10 5 5 0 0 0
2.5 0.25 2.5 0.5 Anticline Jonah Soil Organic Carbon (%) 2.0 0.2 2.0 0.4 Soil Organic Carbon (%) 1.5 0.15 1.5 0.3 1.0 0.1 1.0 0.2 0.5 0.05 0.5 0.1 0.0 0 0.0 0 2.5 0.25 Soil Organic Carbon (%) 2.0 0.2 Wamsutter Recovery of SOM 1.5 0.15 Change: predisturbance to seven 1.0 0.1 years after reclamation. TOC TN 0.5 0.05 % change Anticline 72 88 0.0 0 Jonah -45 -197 Wamsutter 3.7 -1.7
Conclusions • Stockpiles in semiarid region may not be affected by depth, at least in the short-term; • What about age? • Compared with degraded reference sites, reclaimed sites seem to recover or exceed original SOM levels within seven years; • Possibly due to increased herbaceous vegetation • Potentially mineralizable carbon recovers more slowly; • Possibly due to loss of soil structure, which protects labile SOM from mineralization, and continued accelerated mineralization, lack of woody species… • Interest in reclamation research is as variable as annual rainfall.
Thanks to • Calvin Strom • Cally Driessen • Amber Mason • Jennifer Faulkner • Leann Naughton • Luke Driessen • Kristi Bear • Todd Loubsky • K.C. Harvey, Inc. • Gary Austen, BP America • Pete Guernsey, QEP Resources • Ralph Swift, Encana Exploration • UW School of Energy Resources • Wyoming Reclamation & Restoration Center
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