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Managing CBM Product Water A Learning Process With Outcomes. James W. Bauder Krista E. Pearson Department of Land Resources & Environmental Sciences Montana State University - Bozeman. Background Information.

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Managing CBM Product Water A Learning Process With Outcomes

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Managing CBM Product WaterA Learning Process With Outcomes

James W. Bauder

Krista E. Pearson

Department of Land Resources & Environmental Sciences

Montana State University - Bozeman

Background Information

  • Extraction of CBM requires withdrawal of large amounts of saline-sodic water from coal seams containing methane.

  • Projections call for disposal or management of one quarter million acre-feet of product water annually in the Powder River Basin.

Coal bed methane development is neither new nor confined to the Powder River Basin.

Photo courtesy of Dudley Rice, U.S. Geological Survey


  • CBM Product Water – What does it look like?

  • What are the interactions between CBM product water and the landscape?

  • Can we effectively manage CBM product water?

CBM Product Water – What does it look like?

  • The common signature of coal bed methane product water is salinity x sodicity.

Wildcat Creek, Campbell County, WY – Tributary to Little Powder River

What is saline water and why is it considered saline?

  • Saline water has a relatively high concentration of dissolved salts.

  • Salinity of water is referred to in terms of total dissolved solids (TDS).

    • Salinity is estimated by measuring the electrical conductivity (EC) of water.

  • The U.S. Department of Agriculture defines water with an EC greater than 3.0 dS/m as saline.

What is sodic water and why is it considered sodic?

  • The sodicity of water is expressed as the sodium adsorption ratio which is:

  • Sodic water is any water with a SAR greater than 12. Sodic water is not necessarily saline.

Chemistry of CBM Product Water upon Surface Dispersal

Holly Sessoms

MSU Graduate Research

Objective: Determine the behavior of chemistry of CBM product water in stream channels.

CBM Product Water Chemistry

  • CBM product water is bicarbonate rich and under pressure in coal seams.

  • When product water is exposed to the atmosphere, discharged into surface water or applied to soil, sodium bicarbonate undergoes the following reaction:

    NaHCO3 H+ + CO3-2 + Na+

CBM Product Water Chemistry

  • Free carbonate (CO3-2) in solution is now available to bind with calcium in the surface water or soil to form calcium carbonate, i.e., limestone or calcite.

    Ca+2 + 2HCO3- CaCO3- + H20 + CO2

CBM Product Water Chemistry

  • The dissolution of sodium bicarbonate (NaHCO3-) also causes pH to increase with the formation of sodium hydroxide (NaOH):

    Na+ + H+ CO3 CO2 + Na+ +OH-

CBM Product Water Chemistry

  • In summary, sodium bicarbonate-rich CBM product water will initiate the precipitation of calcium carbonate causing:

    • SAR will increase

    • EC values may decrease slightly

    • pH will increase

CBM Product Water Chemistry

  • In a laboratory experiment at MSU, water qualities 6, 7, and 8 with shown initial pH, EC, and SAR values were exposed to the atmosphere for a 9 day period. Initial pH, EC, and SAR reflect changes in CBM product water below the outfall point.

Change in water chemistry for three water qualities over a 9 day time period

(subject to evapoconcentration).

Initial pH

Final pH

Initial EC

Final EC

Initial SAR

Final SAR

% Change EC

% Change SAR




























Average % Change



Soil Chemistry Responses to Saline-Sodic Water

Kimberly Robinson

MSU Graduate Research

Objective: Determine how soils which may be subjected to irrigation will react with repeated wetting with saline-sodic water.

Soil Chemistry Responses to Saline-Sodic Water

  • More than 4 dozen soil materials were collected at sample sites within the Powder River Basin.

  • The samples were leached with various water qualities and soil chemical changes were assessed.

Irrigation Simulation Conditions

  • Water Quality

    • Powder River

      • EC = 1.6 dS/m SAR = 4.5 pH = 8.0

    • CBM Product Water

      • EC = 3.1 dS/m SAR = 13.0 pH = 8.0

  • Irrigation Treatment

    • Powder River:

      • 1x 5x 5x then distilled water

    • CBM Product Water:

      • 1x 5x 5x then distilled water

What are the common difficulties with the use of sodic water for irrigation?

  • Use of sodic water for irrigation can be risky business on soils having significant amounts of swelling clay. On such soils:

    • Sodium changes soil physical properties, leading to poor drainage and crusting, which can affect crop growth and yield.

    • Irrigation with sodic water on sandy soils does not cause crusting and poor drainage. However, if the water is saline-sodic, it may affect crop growth and yield.

Effect of EC and SAR of applied water on relative hydraulic conductivity (Source: Shainberg and Letey, 1984).

Suggested range in EC and SAR of irrigation water for various soil textures

Source: Western Fertilizer Handbook

1. Thresholds for irrigation.

What are the common problems or difficulties with the use of saline water for irrigation?

  • Crop production becomes a problem as salts accumulate in the root zone high enough to negatively affect plant growth.

  • Excess soluble salts in the root zone restrict plant roots from withdrawing water from the surrounding soil.

Crop Tolerance to Saline Water

Salinity & Sodicity Tolerance of Selected Plant Species of the Northern Cheyenne Reservation

Nikos J. Warrance

MSU Graduate Research Objective: Understand how native and culturally significant plant species would respond to increases in salinity and sodicity.

Tolerance and/or sensitivity of selected plants on the Northern Cheyenne Reservation to salinity, sodicity, and flooding

  • Understand how native and culturally significant plants would respond to increases in salinity and sodicity.

  • A list of native and culturally significant plant species was obtained from the Department of Environmental Protection, Northern Cheyenne Tribe.

  • A thorough search of references dealing with salinity, and sodicity tolerances for the plants in question was then undertaken.

Examples of culturally significant plant species of the Northern Cheyenne Reservation

  • Sensitive (EC < 2 dS/m, SAR 1.6 - 8

    • June/Service Berry

    • Red Osier Dogwood

    • Red Shoot Goose Berry

    • Chokecherry

    • Wild Plum

    • Quaking Aspen

    • Leafy Aster

    • Red Raspberry

  • Moderately Sensitive (EC 2-4 dS/m, SAR <8)

    • Common Spikerush

    • Field Horsetail

    • Horsemint

    • Sweet Medicine

    • Sandbar Willow

    • Snowberry

    • Cattail

    • Sweet Grass

    • Saw Beak Sedge

    • Stinging Nettle

    • Western Yarrow

Recommended Wetland Species and Aggressive Invaders

Dry/moist transition area species include:

  • Canada wildrye (Elymus canadenisis)

  • Slender wheatgrass (Elymus trachycaulus)

  • Western wheatgrass (Pascopyrum smithii)

  • Tall wheatgrass (Thinopyrum ponticum)

    Native and survivors:

  • Inland saltgrass (Distichlis spicata)

  • Prarie and Alkali cordgrass (Spartina pectinata and gracilis)

  • Baltic rush (Juncus balticus)

  • Nuttalls alkaligrass (Pucinellia nuttalliana)

  • Foxtail Barley (Hordium jubatum)

    Wet area and in channel survivors or invaders include:

  • American bulrush (Scirpus americanus)

  • Sea Coast bulrush (Scirpus maritimus)

  • Baltic Rush (Juncus balticus)

Screening for Salt Tolerant Forage Species

Allison Levy

MSU Undergraduate Research

Objective: To determine the survivability and early plant biomass production of sixteen different forage species irrigated with water qualities that have been chosen to represent conditions of water surface supplies that could result from coal bed methane development.

Common Name

Scientific Name


Zea mays


Elymus angustus

Tall Wheatgrass

Agropyron elongatum

Crested Wheatgrass

Agropyron cristatum


Kochia scorparia


Bicolor (L.) moench

Intermediate Wheatgrass

Agropyron intermedium

Newhly Wheatgrass

Elyrtigia repens x Pseudoroegneria spicata

Tall Fescue

Festuca arundinacea

Paiute Orchardgrass

Dactylis glomerata L.

Slender Wheatgrass

Agropyron trachycaulum

Perennial Ryegrass

Lolium perennal


Hordeum valier


Beta vulgaris L.

Hi Mag Tall Fescue

Festuca arundinacea hi mag

2nd Gen. Alfalfa

Medicago sativa

Species Used in Screening for Salt Tolerance

Common Name

Scientific Name

Tall fescue

Festuca arundinacea

Intermediate wheatgrass

Agropyron intermedium

Slender wheatgrass

Agropyron trachycaulum


Elymus angustus


Bicolor (L.) moench


Zea mays

Valier hay barley

Hordeum valier

The Short List

The short list consists of eight forage species that were chosen for a long-term experiment to assess forage biomass production in greenhouse conditions.

Summary: Lessons Learned

  • Sustainable CBM product water management requires rigorous monitoring and coordinated management. The essential requirements include:

    • Soil, water, and plant baseline information.

    • Quantity and quality of CBM product water.

    • Rigorous monitoring at all points.

    • Coordinated water management with multiple strategies.

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