Intro
CBM EIS Update

Prepared by Dan Arthur, P.E. - ALL Consulting Tulsa, Oklahoma
Highlight of Issues (Partial List)

Hydrology Impacts Groundwater Drawdown/Recovery Surface Water Impacts Water Quality/Degradation Soils/Vegetation Impacts Soil Impacts from CBM Water Impacts to Vegetation Gas Drainage Federal – Indian Trust Issues Socioeconomics/Environmental Justice Wildlife Impacts
State and Federal Planning Areas

BLM Planning Area Billings RMP Area Powder River RMP Area State Planning Area Statewide CBM Emphasis Areas Powder River Basin Blaine County Park County Gallatin County
BLM and State Planning Areas Stratigraphy in the PRB (Generalized)

The Powder River Basin of Montana is expected to have the majority of CBM development and was emphasized in the analysis. Targeted Coals for CBM are Paleocene Fort Union, all of which are in the Tongue River Member

Water Resources

Water Resources Technical Report (ALL, 2001) Geology & Hydrogeology Water Use and Quality Water Resources Impacts Groundwater drawdown Analysis Water balance of groundwater resources Surface water potential impacts Mitigation and BMPs Other Studies Groundwater Modeling (MBMG) http://www.all-llc.com/CBM/netscapePPT/montanaEIS_files/outline_exp...

1 of 4 4/6/2009 3:33 PMBest Management Practices (ALL/MBOGC – DOE Project)

CBM Water Characterization
Water Use Map of the PRB

Water Use Map of the PRB illustrating distribution of wells along stream beds Most water wells are completed in alluvium near stream beds
CBM Development By Watershed

Upper Tongue River has highest potential development 5,800 + wells Eastern Watersheds have lowest with approximately 225 wells

CBM Water Production Rates

Extrapolation of water production rates over an estimated 20 year life yields an averaged production rate from CBM wells of ~2.5 gpm. It is also important to note that this is an estimate based on existing data in Montana and data comparisons from Wyoming. Actual average production may vary from this average assumed rate. To obtain average production rates for CBM wells in Montana, trend analysis was performed for averaged production of produced water at CX Ranch. Results were compared to data from Wyoming.

CBM and the Groundwater Balance

Total Groundwater Resources Estimated 250 billion cu ft of groundwater in coal seams that are expected to be developed in the PRB Estimated Maximum CBM Production An Estimated 4.4 billion cu ft of water could be produced by CBM wells per year based on exponential decline analysis and the RFD’s maximum production numbers in all watersheds of the PRB Approximately 35% of groundwater resources in the development area would be extracted.
Groundwater Monitoring Analysis

Groundwater monitoring data were obtained for analysis of impacts from CBM production. Several monitoring stations exist as a result of coal mine activity in the area.
Groundwater Impacts from CBM

Monitoring Well WR-55 (approximately 0.2 miles from CBM operations) shows drawdown after approximately 11 months of production activities at CX Ranch. Drawdowns of approximately 30 ft are observed. Impacts from coal mining can also be observed.
Potential Surface Water Impacts

Watersheds that would be impacted the most by CBM discharge are those with low flow volumes and low SAR such as Rosebud (near Kirby) where large increases in flow would result from CBM discharge Other watersheds with large flows would be capable of receiving CBM water with little impact
Worst Case Surface Water Impacts

CBM development in Wyoming (50,000 potential wells) would overshadow impacts resulting from development in Montana. Powder River would have an increased annual average flow of 9% with SAR increasing to ~5. Discharge during low flow periods could be dramatic. Little Powder River would have an increased annual average flow of 400% with SAR increasing to ~9. Increased flows would likely cause increased suspended sediment, erosion, and impacts to wildlife, cultural resources, etc.
Soils & Vegetation

S il T h i l R t (ALL 2001) http://www.all-llc.com/CBM/netscapePPT/montanaEIS_files/outline_exp...

2 of 4 4/6/2009 3:33 PMS o il s T ec h n i ca l R epor t (ALL , 2001) Characterization Issues Characterization of CBM water Crop characterization in the Billing and Powder River RMP areas Soils Characterization Impacts of CBM Water Agricultural irrigation Livestock watering Other impacts
Soil Types in the PRB RMP Area

Soils range from loams to clays, but principally loams to silty clay loams

Mean K-Factor for Soils of PRB RMP Area

K-factors are a measure of a soil’s susceptibility to erosion from water. High K-Factors are the most erodible with values over 0.37. Most soils in the PRB have K-factors below 0.37
Mean Soil Salinity of PRB RMP Area

Most soils in the PRB have low salinity Higher salinity soils require better management practices to produce crop yields

Statewide Maximum Soil SAR

SAR is a measure of the soil’s sodicity. High SAR values result in decrease infiltration of water. Soils with fine textures (clayey) are more susceptible to sodicity increases from irrigated water with high SAR
Irrigation Water Salinity and Crop Yield

With normal management practices, the lowest CBM water salinity would have no adverse impacts on crops More salinity sensitive crops such as alfalfa and corn could be affected by the average salinity CBM water Highest salinity CBM water could be used as a portion of the irrigation water supply if mixed with other sources of water
CBM Water Quality Relative to Infiltration

Average CBM water would cause slight to moderate reductions in infiltration Waters with the highest SAR and lowest EC could cause significant reductions in infiltration Waters with the lowest SAR and highest EC would cause only slight to moderate reductions in infiltration
Impacts to Soil and Plants from CBM Water used for Irrigation

The use of high salinity CBM water may affect crop production limiting farmers to grow only more tolerant plant species The use of water may require farmers to modify cropping practices, new equipment, different crop growth, soil profile modifications, etc. Use of CBM water over a number of years may result in increased soil salinity from accumulation Dispersed soils could experience significant erosion due to lack of structure and vegetation
Encouraging Beneficial Use of CBM Water and Best Management Practices

Low salinity and low SAR CBM water could be used for irrigation Moderate salinity and SAR water could be diluted with other irrigation water and applied. Careful monitoring of soils would be required if high salinity and SAR water were used for irrigation, special management practices would have to be followed. CBM water does not appear to be harmful for livestock and could be used as new water supplies to pasture land http://www.all-llc.com/CBM/netscapePPT/montanaEIS_files/outline_exp...

3 of 4 4/6/2009 3:33 P Mwere supplies currently do not exist. Monitoring of Livestock may be required initially as they adjust to the new water supply. Wildlife, Cultural Resources, and other issues could potentially be impacted by CBM operations. Effective use of Best Management Practices and Mitigation can serve to minimize impacts from CBM development and cumulative impacts.

Questions? http://www.all-llc.com/CBM/netscapePPT/montanaEIS_files/outline_exp...

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