Presented at the Central Plains irrigation short course and exposition on February 5-6, 2001 at the Holiday Inn in Kearney, Nebraska.Includes bibliographical references

LaRue, Jacob L.

English

Presented at the Central Plains irrigation short course and exposition on February 5-6, 2001 at the Holiday Inn in Kearney, Nebraska

LaRue, Jacob L., author

Mountain Scholar (Digital Collections of Colorado and Wyoming)

SELECTING SPRINKLER PACKAGES FOR LAND APPLICATION OF LIVESTOCK WASTEWATER Jacob L LaRue Senior Engineer Cascade Earth Sciences Valley, Nebraska Voice: 402-359-6041 Fax: 402-359-6081 Email: jlr1@valmont.com INTRODUCTION Livestock operations have changed dramatically in the last ten years. For example the number of hog farms has decreased from 600,000 to 157,000 in the last fifteen years.(Harkin 1998) During this same time the overall output of pork has increased. This increase of size also indicates an increased concentration of animals. Problems associated with any traditional livestock production unit are multiplied as the size increases. Management of the wastewater stream becomes a major component of the management strategy. Maintaining the environmental quality for the area of the livestock operation is critical to the overall success. Livestock wastes may be applied by a number of methods. Tractor towed manure spreaders or slurry wagons are used to apply to the soil surface. Tractor towed slurry tanks with equipment to'inject'the waste into the soil are used. Another choice is a plow down system where a tractor tows an injection unit attached to a long hose connected to a pump and the lagoon. On-land application units such as fixed head sprinklers, traveling guns or a center pivots are also commonly used. Decisions on the type of waste application system are important to the economics of the livestock operation. Timing is one issue, which plays a key role in determining application methods (Hardeman 1997). Most of the methods listed above are only viable in the spring before the crop is planted or in the fall after it is harvested. Center pivots are not however limited by whether a crop is present or not as they may be used to apply over an active crop. Center pivots, due to their characteristics, are considered to have advantages with regards to applying livestock wastes, particularly from a lagoon with large amounts of water to handle. Some of these characteristics include limited labor input required, application uniformity, ease in handling large quantities of effluent 87 . and particularly the ability to apply to actively growing crops with minimal negative impact to the crop. Operators readily invest in major capital improvements and equipment to facilitate the production of meat or milk by providing the best possible environment for the animals. However most producers have a strong reluctance to invest in more than the minimum required to meet existing local, state and federal environmental regulations for disposal of the wastewater. If the investment does not add value to their operation - why make the expenditure? DISCUSSION Land application of wastewater with center pivot and linear irrigation equipment has been used for more than thirty years. Until the late 1970's the land application package was easy to select, as the choices were limited to relatively high-pressure impact sprinklers (50psi) or the Valley Slurry Shooter™ using high volume sprinklers (90psi). Since the early 1980's the equipment and techniques for irrigating with fresh water have changed dramatically to the point the pressures at the nozzle inlet may be as low as 6psi. Currently more than five major classes of sprinkler packages are being used with many options within each class - pad styles being the main option. In many cases both water for reuse and fresh water are applied with the same equipment. Midwest Plan Service's MWPS-30 (MWPS, 1999) discusses general principles in sprinkler selection relating to fresh water application but does not attempt to quantify any procedure or specifically look at effluent application. Other publications have provided general discussions without offering a specific procedure - Livestock Waste Facilities Handbook (MWPS, 1993), Liquid Manure Application Systems Design Manual (NRAES, 1998) and Agricultural Waste Management Field Handbook (USDA, 1992) Then also in today's world one must take into account the issues and public perception of land application systems. Land application of wastes may be imposing in some locations, potentially dangerous conditions relative to environmental quality (Hegde 1997). We must insure any equipment being used for land application meets public scrutiny. OBJECTIVE How does one select the optimum sprinkler package for a particular waste water situation? DISCUSSION Currently many sprinkler packages are selected by irrigation dealers and customers based on personal experience and preference. Some of these general sprinkler categories are: 88 type orifice diameters 辜 ~ressure drag hose 4/64 to 24/64in none 6 to 10psi fixed pad 4/64 to 24/64in fixed 6 to 20psi rotating pad 4/64 to 24/64in rotating 15 to 30psi impact 9/64 to 40/64in n/a 40 to 60psi high volume guns 0.50 to 0.94in NIA 45 to 90psi A systematic approach does not exist to assistance in the decision making process. Experience has taught that "if it worked the last time, it should work again" or "that is what my neighbor's doing". It is recommended looking at each system individually to make the selection on the best information available. To begin the process information is required about the particular application: Material being applied Estimated solids content Organic material Inorganic material Particle size Environmental constraints Ground water wells Neighbors Tile line Management issues Operating costs Energy costs Maintenance CAFO permit constraints Then look at how the wastewater stream is handled -Collection Treatment (if any) Storage Pump system Position of inlet of the pump We have tried to develop a quantitative approach to the selection of a recommended sprinkler package based on the information collected. To do this we apply the information to a ranking system 89 First assign 1-5 points for each item based on the headings -Value to assign 1 2 3 4 5 Item RanQe 1 - Solids content <0.5% 1.0% 2.0% 3.0% >4.0% 2 - Particle size small medium large 3 - Pump impeller closed semi open open 4 - Pump inlet floating bottom 5 - Labor costs low medium high 6 - Energy costs high medium low 7 - Environment high medium low 8 - Storage 2 stage 1 stage pit Lagoon lagoon 9 - Collection flushing scraper 10 - Pump style fresh water slurry chopper 11 - Uniformity (CU) 85 75 65 Minimum number of possible points - 11 Maximum number of points - 55 This is the range within which to work with the lower the number tending to indicate a wastewater stream, which has limited solids content and small particles. The closer a number approaches 55 the thicker the wastewater and larger the particles. Some of the items are relatively easy to estimate - others such as the solids content are very difficult. The following table is one way to characterize the solids in a waste stream. First visualize a bucket with the manure in it. Then start tipping the bucket -AnqIefrom qround 45 degrees above 30 degrees above 15 degrees above O degrees, bucket parallel to ground how it flows estimated solids smooth stream in small globs in quarter sized globs fist sized globs 90 1 to 2% 3% 4% 5% 45 degrees, pouring down thick chunks 6% This table allows a method to roughly estimate the solids content based on how the effluent flows. Using the point total one goes into the table to select a recommended sprinkler type. Point Type Total 10 to 19 low pressure on drops 20 to 29 low pressure on drops 30 to 39 impact 40 to 50 high volume guns Pad fixed rotating n/a n/a Pressure 6 to 20psi 15 to 30psi 40 to 60psi 45 to 90psi A worksheet was developed to allow a person to'fill-in-the blank'with the data and information collected. One does the best to estimate and make a selection based o experience and quantitative data if available. 91 SQrinkler Selection Worksheet Item Rankinq 1) -Solids content - consistanc 2) Particle size inchesy 3) Pump impellor 4) Pump inlet 5) Labor costs $/hr 6) Energy costs —¢/kw-hr or gallon 7) Environment . issues 8) Storage 9) Collection 10) Pump style 11) Uniformity Ranking ~~e 11 to 19 20 to 29 30 to 39 impact 40 to 55 high volume guns Sprinkler package selected -Pad type if applicable -Pressure selected -Total Points pad fixed rotating n/a 92 % pressure 6 to 20psi 15 to 30psi 40 to 60psi 45 to 90psi Testing of the selection process Example 1 - Single stage dairy lagoon, limited labor, no neighbors within two miles, flushing system, wants to pump from bottom, is not nutrient limited. Primarily system to be used for land application and not irrigation. Item ranking 1) Solids content -2) Particle size 3) Pump style 4) Pump impellor 5). Pump inlet 6) Labor costs 7) Energy costs 8) Environment 9) Collection 10) Storage 11) Uniformity thick consistancy 4% 3/16 inches (pieces of corn cob) slurry semi open on bottom of lagoon 9.25 $/hr 4.25 ¢/kw-hr or gallon no issues flushing pit low 4443542 5155_ Rankinq 10 to 19 20 to 29 30 to 39 40 to 50 血eimpact high volume guns Total Points 逗fixed rotating n/a 42 pressure· 6 to 20psi 15 to 30psi 40 to 60psi 45 to 90psi Sprinkler package selected minimum of impact sprinkler, hig volume gun suggested Pad type if applicable· -Not applicible to impact or volume guns Pressure selected -Minimum suggested of 45psi 93 Example 2 - two stage hog lagoon, limited labor, no neighbors within two miles, plug/pull system, wants to pump from top w/ floating pump, wants no problem with plugging and will use for irrigation Item ranking 1) Solids content -2) Particle size 3) Pump style 4) Pump impellor 5) Pump inlet 6) Labor costs 7) Energy costs 8) Environment 9) Collection 10) Storage 11) Uniformity Ranking 10 to 19 20 to 29 30 to 39 40 to 50 thin <.5% 3/16 inches (trash in lagoon, in-organics fresh water closed on top of lagoon 20.00 $/hr 2.25 ¢/kw-hr or gallon no issues flushing two stage lagoon high 並匹impact high volume guns Total Points ~ad fixed rotating n/a ~ressure low low to medium medium to high high Sprinkler package selected From ranking - rotating pad But customer suggestions wants no problems 14111425111l2 2 A combination system may be the best choice. Utilizing the wider spacing of the sprinklers with rotating pads for the first portion of the center pivot until a larger nozzle size is reached. 94 SUMMARY The model has proved to be successful in the actual situations where it has been applied as a decision tool. This is process is not perfect and one must apply reasonable judgement in selecting a sprinkler package. Also the process is only as good as the data which is collected. As with any tool care must be taken to consider all factors and apply appropriately. In addition center pivots can successfully used to meet requirements for minimizing environmental impact of spray drift and runoff and also meet customer requirement for monitoring and reporting by the selection of equipment options. Livestock systems continue to evolve. Rations, genetics and housing systems have changed significantly in the last five years. Feeding and manure handling systems continue to change. As production units change the irrigation industry is working on equipment to continue to meet customer's requirements. Center pivots continued to be an accepted option for land application of wastewater generated from a CAFO particularly if a lagoon or storage reservoir is used. This type of equipment provides the control and monitoring capabilities required by many CAFOs (LaRue 1998). In many cases the CAFO may have different constraints from traditional farm livestock units. In these cases, alternative treatment such as the Sheaffer MRRS, (Sheaffer, 1998) anaerobic digestion or other methods may need to be utilized to reduce the nutrient, odor and sludge. Once the treatment process is completed, the remaining liquid fraction may be land applied with a center pivot or other system designed to handle large volumes of low nutrient strength water. As is always the case the operator must be aware and follow local and state regulations. REFERENCES Dougherty, Mark, Geohring, Larry, Wright, Peter, Liquid Manure Application Systems Design Manual, NRAES-89, Northeast Regional Agricultural Engineering Service, Cornell University lthica NY, 1998 Gilley, James R,, 1983, Suitability of Reduced Pressure Center Pivots, Journal of Irrigation and Drainage Engineering, Vol 110, No. 1, 95 Hardemann, T.L., Mickelson, S.K., Baker, J.L., Kanwar, R.S., Lorimor, J.C., Melvin, S.W., 1997 Effects of Rate, Method, and Timing of Swine Manure Application on Groundwater Quality, 1997 International Summer Mtg. of ASAE, Paper 97-2145, Minneapolis Minnesota Harkin, Tom, 1997 report on animal waste issues, The District Leader January 1998 Hegde, Poornima and Kanwar, R.S., 1997 Impact of Manure Application on Groundwater Quality, 1997 International Summer Mtg. of ASAE, Paper 97-2144, Minneapolis Minnesota Kifco /Ag-Rain, Havana, Illinois LaRue, J L, Howard, H D and Dorsett, WE, The Use of Center Pivots to minimize Enviromental Impact of Land Applied Swine Manure, 1998 International Summer Mtg. of ASAE, Paper 98-2113, Orlando Florida LaRue and Howard, 1998, Modification and Testing of Commercial Center Pivots to Apply Dairy Waste Slurries and Meet EQIP Program Requirements, 1998 International Summer Mtg. of ASAE, Paper 98-2100, Orlando, Florida Midwest Plan Service, Sprinkler Irrigation Systems, MWPS-30, 1st edition, 1999, Ames Iowa Midwest Plan Service, Live~tock Waste Facilities Handbook, MWPS-18, 3rd edition, 1993, Ames Iowa Northeast Regional Agricultural Engineering Service, Liquid Manure Application Systems Design Manual, NRAES-89, 1998, Ithaca, New York Sheaffer, Jack, Anderson, Paul, Ellis, Stuart and Johnson, John, Enviormentally Friendly Manure Treatment for Large Scale Confined Animal Feeding Operations, 1998 Animal Production Systems and the Environment, Des Moines Iowa United States Department of Agriculture, Agricultural Waste Management Field Handbook, Part 651, 1992, Washington DC Valmont Industries Inc., Livestock Waste Management through Center Pivots, Wastewater Intelligence volume 1, AD10182 1988 96 

Selecting sprinkler packages for land application of livestock wastewater

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Selecting sprinkler packages for land application of livestock wastewater

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