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Transforming Prairie-Dog Land Into Productive Land, The "TOOLBOX" Way Managed Irrigation is a strategic beneficial use of coalbed natural gas discharge water. It’s strategic because it’s a science. Thousands of acres in the Powder River Basin have been transformed into productive use by applying a little chemistry to the produced water and adhering to traditional agronomic principles. Sheridan rancher Eddie Piltch has used the technique to change his dry wheat fields into productive hay fields. “It’s been super,” he said. “Not 100 percent but 120 percent.” If the companies did not irrigate with the CBNG water, he wouldn’t have had any water on his place at all, he added. This is beneficial use at its finest. As defined by law, beneficial use is when “…produced water is of good enough quality to be used for wildlife or livestock watering or other agricultural uses and that the produced water is actually put to such use during periods of discharge.” Other ranchers like Piltch are finding beneficial use through managed irrigation. Neil Brinkerhoff said it’s a great opportunity. “I’m all for the water,” he said. Managed irrigation is another “tool” out of The Water Management Toolbox. Ranchers like it because it allows them to productively use what was formerly dry, “prairie dog” land. Producers like knowing there is a variety of effective and site-specific water management tools available in the toolbox. “We need to find use of the CBNG water on our land,” he said. Larson believes there are a variety of things ranchers and farmers can do to beneficially use the water on their land. He also believes that current legal actions are trying to hinder the possibilities for future beneficial uses. Many agree and believe options exist. Under the category of managed irrigation, more than 30 options exist. Several automatic and manual irrigation systems are available including: center pivot sprinklers, side-roll/wheel line sprinklers, hand- moved or fixed solid set sprinklers, big gun sprinklers, surface drip, subsurface drip, gated pipe flood and ditch flood. More commonly, ranchers are using center pivot and side-roll sprinklers. Center pivots provide a fast irrigation method and the coverage is sufficient. They are more expensive than side-roll sprinklers (costing approximately $30,000 per pivot), but less labor is involved. The electric-driven wheels travel freely up and down hills. Approximately 750 gallons per minute of water is dispersed from the big pivots. The smaller pivots disperse about 150 gallons per minute. Side-rolls are typically used in concert with center pivots for hard-to-reach areas. They are about ¼ mile long, on average. They are manual sprinklers and shut down every 12-24 hours. Moving them is more labor-intensive. Side-rolls are about one-tenth the cost of center pivots. Individual sites are initially evaluated to predict and ensure the project economics, and in all cases, the operators work with the landowner to develop a system that will meet the rancher’s objectives. Managed Irrigation Kevin Harvey is a board-certified professional soil scientist. His success with managed irrigation is evident across the Powder River Basin. Harvey is currently the Principal of KC Harvey, LLC., a soil and water resources consulting firm based in Bozeman, Montana. He has been involved with irrigation projects for five years. “I see it as an opportunity. Managed irrigation is used as a water management technique because the landowner wants and can use the extra forage for livestock.” Harvey said that typically, 25 to 30 inches of CBNG produced water are applied per season to grow crops such as alfalfa and forage grasses in the Powder River Basin. A rough cost is between $0.06 to $0.11/ bbl for a 100-acre system. When the site is finished, site closure plans are done in cooperation with the landowner. Harvey said, “The primary goal of site closure is to leave a physically and chemically stable site capable of moving towards a sustainable vegetative community that meets or exceeds landowner goals.” Managed Irrigation Chemistry 101 It’s called managed irrigation because it’s controlled.
By neutralizing the water with an acid like sulfur, calcium amendments such as gypsum can be added to offset the sodium-rich water. It’s like balancing a chemical equation. Adding sulfur and gypsum is equivalent to adding standard fertilizers because these standard fertilizers often have concentrations of the exact same elements. The gypsum is calculated to a specific amount according to the sodium content of the water at that site. When the equation is properly balanced, the “crusty” topsoil problem is eliminated because the gypsum counteracts the sodium. Soil permeability and porosity are now satisfactory to grow crops. Noticeable Improvements Initially, baseline soil conditions of the irrigation areas are collected and analyzed by a team of irrigation experts before the project begins. A “soil and water prescription” is then developed to allow long-term irrigation with CBNG water. “They watch the water real close,” said Piltch, who began irrigating with CBNG water five years ago. Brinkerhoff agrees, and said that because the project is so carefully calculated, he is confident the soils are being protected. “In three years, I haven’t had one problem.” He believes the gypsum is allowing better infiltration in the soil, resulting in better crop tonnage per acre. He’s doubled his hay production since the irrigation project began. Rancher Ross Peterson, also from Sheridan, is confident the program has robust monitoring protocals. Peterson has been irrigating since 2001. So has Charlie Larson. Larson yielded over three tons of hay per acre last year. He said he beat the state average for tonnage per acre. “I have had real good luck. The extra water sure helps when you are in the middle of a nine-year drought.” Another unanimous managed irrigation benefit is allowing cows to graze on pastures that were previously unfit for cattle. Brinkerhoff said he doesn’t have to use as much hay as before, because the cows can now utilize these newly irrigated pastures. He said he had hay leftover last year for the first time ever. The Floyds, who ranch in Gillette, say it is fantastic. They say the wildlife love the extra water. Furthermore, all of the ranchers agree that the power and access roads have provided additional benefits to their ranches. Subsurface Drip Irrigation Systems Another alternative to center pivots and side-roll sprinkler systems is the subsurface drip irrigation method, which is growing in popularity. It differs from managed irrigation because it irrigates the soil from the roots up. It is another “tool” out of The Water Management Toolbox. More choices allow flexibility to both the producers and the landowner. In the Powder River Basin, this is a must. BeneTerra, LLC, a water management company that operates subsurface drip irrigation systems, has a mission to harvest water for agricultural use. “We are agriculturists,” said partner John Zupancic. “Instead of pumping the water away we want to use it beneficially for agricultural purposes.” He said agricultural producers have a lot to gain in the CBNG arena, where water is such a huge component. Dee and Edward Reisch manage the 4X ranch in Sheridan, where a subsurface drip irrigation system was installed. “We are really impressed,” said Dee Reisch. Reisch thinks the system is beneficial to the landowner because the water stays in the ground. “The grass fills in quickly and the fields are left untouched.” The system works by evenly applying small amounts of water over a large surface. The system supplies sub-surface water year-round. Reisch said that because the CBNG water is naturally warmer, freezing is not an issue. BeneTerra said year-round irrigation is beneficial to both energy producers and agriculturists. The laterals are placed two to three feet underground. (Click here to see a schematic drawing of the system.) There is about a 40-60 inch distance between each lateral. Each lateral is lined with small “pin-points,” referred to as emitters. Water drips out from the individual pin-points at a rate of 0.75 to 1.5 gallons per day. One acre typically has 3,000 pin-points. Zupancic said they can deliver 40-60 inches of water per acre-year. This means a 100-acre field can handle three to four million barrels of water in a year. Other scientists agree, like Patsy Ballek, who works for Windsor Energy. BeneTerra has a patent pending for the system, which places sodic water beneath the surface. Ballek said this is what makes the system so unique. “When the water is released at root level the plants take up the water, not the minerals.” Sodic water is characterized by having a sodium adsorption ratio greater than 15 and an electrical conductivity less than four. As this water travels through the soil, it dissolves calcium. Much like the managed irrigation approach from above, the calcium is what offsets the sodium. So the key is placing the laterals correctly. Lateral placement is dependent on the amount of calcium in the soil. Zupancic said the water supply meets or exceeds the demands of crops. Using excessive water causes water and salts to move below the root zone. The Reischs have noticed improvements in the soil. “The root structure in the soil is amazing,” said Reisch. “The plants have to grow deep to reach the water. This strengthens the forage.” She said a line was replaced and the roots were deeper and a lot stronger in the fields that were irrigated with the subsurface drip system. Zupancic believes the extra water below the root zone could also recharge future aquifers by leaching into the groundwater. He said the Department of Environmental Quality highly regulates this. “After production is gone there is an opportunity for someone to sink a well in and recapture the water,” said Zupancic. Zupancic said they like to use cool-season crops with longer growing seasons such as alfalfa, brome grass and fescue. But, he said it is really up to the landowner and what crop will suit their operation the best. He said highly salt-tolerant crops are not essential. BeneTerra is in their third year of managing subsurface drip irrigation projects. Currently, they have 200 acres in production and in the next 18 months, 1,000 acres will be under production. “It is working well,” said Zupancic. “Both the soil and the crops look good.” BeneTerra does not sell the systems. They design, install, and operate them. Instead, they charge the producer for the CBNG water. “It is quite the system,” Reisch said. “ I encourage people to go out and take a look.”
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