1999 Beef & Bison Production Field Day
A New Project Proposal - Using Coal Combustion
By-products for Feedlot Surface Stabilization
Scott Birchall, Extension Livestock Waste Management Specialist
Carrington Research Extension Center
Livestock producers in North Dakota are seeking a low cost alternative to placing concrete in feedlots. Earthen pens and lane-ways do not withstand concentrated livestock traffic when wet for any length of time such as during spring thaw. As the integrity of the pen or lane-way surface breaks down, deep mud and poor drainage reduce animal performance and health, increase odor emissions and prevent regular maintenance operations such as manure removal. Commonly, the soil/manure interface layer is damaged resulting in deeper leaching of nutrients and an increased risk of groundwater pollution.
Sufficient evidence exists to suggest that using Coal Combustion By-products (CCBs) can lead to significant improvements in pen and lane-way conditions. Work performed at the Energy and Environmental Research Center indicates that several lignite coal ashes are suitable for use in feedlot surfacing - either in constructing a concrete-like surface or in stabilizing the existing soils [Pflughoeft-Hassett, 1996; Moretti, 1993a&b]. Table 1 describes some of the different classes of CCBs, however, their properties will vary with the source of the coal and the combustion process. Therefore, the suitability of a specific CCB for feedlot surfacing must be investigated before placement.
Table 1: Types of coal combustion by-products and their characteristics.
|Fly ash||Non-combustible particulate matter removed from stack gases.||Powdery, silt-like.|
|Bottom ash||Material collected in dry bottom boilers, heavier than fly ash.||Sand-like, some coarse agglomerates.|
|Boiler slag||Material collected in wet bottom boilers or cyclone units.||Glassy, angular particles.|
|FGD* material||Solid or semi-solid material obtained from flue gas scrubbers.||Fine to coarse (dry or wet).|
|FBC** material||Mainly bed material (sand or other inert material), and a mix of fly ash and bottom ash.||Fine to coarse|
*Flue Gas Desulferization
** Fluidized Bed Combustor
Feedlot cattle suffer reduced weight gain as a result of muddy pen conditions. Research at Texas A&M University identified a 14% reduction in weight gain when coping with 4 to 8 inches of mud. In just six weeks of muddy conditions, this hidden cost may penalize producers by $11/head. When the mud depth was 24 inches, the reduction in weight gain was 25% [Sweeten et al, 1987].
Improving pen drainage will also reduce odor emissions. Watts et al (1992) found that wet manure on the pen surface produced 60 times greater odor concentration/intensity compared to a dry surface. A more durable pen surface would allow for more frequent manure removal, reducing the risk of having a significant depth of manure accumulated when rain occurs. A durable pen surface would also promote better drainage of runoff from the pens by limiting the formation of holes and low spots.
Researchers at Texas A&M University placed two ash treatments (crushed bottom ash and fly ash rototilled into the pen surface) into feedlot pens in 1993. Pen conditions were evaluated visually for two years following placement. The crushed bottom ash treatment proved superior to the untreated pen surface for all four thicknesses tried. Crushed bottom ash at 6" and 8" depths performed better than other treatments (though there was little difference between the two thicknesses). The fly ash rototilled into the pen surface treatment deteriorated at areas of high pressure around feed bunks and water troughs [Sweeten, 1996]. A related study demonstrated that a straight fly ash blanket needed less maintenance than fly ash rototilled into the pen surface.
In 1993, fluidized bed combustor (FBC) ash was used to stabilize soil in a feedlot in Iowa [Greenless et al, 1998]. The results indicated that the FBC treated soil strength increased by 200% to 300% compared to an adjacent untreated feedlot. Treated samples were better able to withstand immersion in water, however, three freeze/thaw cycles reduced the compression strength of all samples. The feedlot pen treatments were completed using machinery normally available locally at a cost of $0.23/ft2 (the ash was provided free of charge).
A separate Iowa project combined reclaimed fly ash (which the consistency of aggregate), with fresh fly ash, and placed the mixture directly on the surface of a feedlot. The combined material was conditioned with water, disced, and compacted to provide a dry, solid surface for the feedlot. Two months of monitoring indicated good performance [Midwest Fly Ash and Materials].
A feedlot project initiated in Ohio during 1992 used lime-enriched flue gas desulfurization (FGD) material to construct both livestock pens and hay storage pads [ACAA, 1999; Daines, 1997]. In many cases, farmers were able to place the material using their own standard equipment. The demonstrations have been highly successful with 174 commercial pads constructed in 1997/98. The FGD producer received a "permit-to-install" from the Ohio EPA so that farmers are not required to obtain any further authorization to install pads covered by the permit. The cost of the FGD pads was approximately $0.46/ft2 and estimated to be 25% to 65% less expensive than stone aggregate or concrete respectively.
Another study investigated using FBC ash on an experimental dairy farm in Pennsylvania. Monitoring of heavy metal levels in the leachate under the pavement did not detect any element at unacceptable levels [Stout, 1999].
A new project to demonstrate the use of North Dakota lignite coal ash for surfacing feedlots is currently being reviewed for funding. The criteria evaluated in the demonstration will include engineering and environmental performance as well as the economics of procuring the materials and placement techniques. The proposed is to demonstrate up to 4 different surface types at the NDSU Carrington Research Extension Center Bison research facility. It is anticipated that some of the surfaces will have properties similar to concrete for use in the feeding/watering areas. Other surfaces will designed to provide a "softer" more soil like surface that provides drainage and support for cleaning equipment. Feed-roads will be surfaced with lignite bottom ash. In the second year of the project, two or three livestock producers in other parts of the state will have the opportunity to trial promising CCB treatments.
The participants in this proposed effort are the University of North Dakota (UND) Energy & Environmental Research Center (EERC), the North Dakota State University (NDSU) Carrington Research Extension Center (CREC), the NDSU Department of Agricultural & Bio-systems Engineering, and several North Dakota utilities and ash marketers.
American Coal Ash Association "Livestock Pads Made From CCPs" ACAA Ash at Work, April 1999; p21.
Daines, M. "Lime-Enriched FGD Product for Feedlot and Hay Storage Base". 1997 EERC CCB Utilization Workshop, Minneapolis, MN, September 29-30, 1997.
Greenless, W.J., Pitt, J.M., Dawson, M.R., Chriswell, C.D. and Melvin, S.W. (1998). "Stabilizing cattle feedlot soil with fluidized bed combustor ash."
Trans ASAE. 41(1):203-211.
Midwest Fly Ash and Materials "Use of Class C Fly Ash for Livestock Feedlot Applications" Bulletin #1.
Moretti, C.J. "Fly Ash Utilization in McClean County, North Dakota". Final Technical Report, March 1993.
Moretti, C.J. "Development of Fly Ash-Based Slope Protection Materials for Waste Disposal Ponds". Final Technical Report, February 1993.
Pflughoeft-Hassett, D.F.; Dockter, B.A.; Eylands, K.E.; and Hassett, D.J. "Survey and Demonstration of Utilization Potential of North Dakota Lignite Ash Resources," EERC report 96-EERC-04-01 to the Industrial Commission of North Dakota, April 1996.
Stout, W.L.; "Low-Cost Way to Pave Feedlots". Agricultural Research, January 1999, pp22-23.
Sweeten, J.W., Lubinis, L., Durland, R. and Bruce, B. (1987). Feedlot Mounds. Great Plains Beef Cattle Handbook. GPE-7525
Sweeten, J.W. 1996. Texas Agricultural Extension Service Result Demonstration Report. "Feedlot Surface Condition Coal Ash Surfacing vs. Control."
Watts, P.J., Jones, M., Lott, S.C., Tucker, R.W. and Smith, R.J. (1992). "Odor Measurements at a Queensland Feedlot". ASAE. Paper 92-4516.
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