Civil and Environmental
Engineering and Geodetic Science
Food, Agricultural and Biological Engineering
Civil and Environmental
Engineering and Geodetic Science
Excessively muddy conditions at livestock feeding and watering areas can have detrimental effects on farm operations. The animals have to expend a considerable amount of energy just to move through mud. This can result in higher feed costs as well as reduced weight gain by livestock. Hay bales stored on wet ground can take on moisture, leading to early deterioration and as much as 50% spoilage. Avoidance of muddy conditions can result in increased animal performance and significant monetary savings for producers, as well as a cleaner farm environment.
To avoid muddy conditions, it is often desirable to construct a stable, impermeable, and sloped surface so that water drains off rather than accumulates on the area. Flue Gas Desulfurization (FGD) material is currently being used as an inexpensive and reliable product in the construction of feeding pads. It is also being used for constructing pads for hay bale storage so that the bales can be protected from mud and moisture. Pads constructed of FGD are not as strong, hard, or durable as concrete, but for these applications, FGD pads improve conditions of the area substantially for usually far less expense than concrete.
The objective of this publication is to provide livestock producers, landowners, and supervising agency personnel with an overview of the use of FGD product in pad construction. This fact sheet includes information on pad installation, regulatory constraints, pad location and sizing, maintenance and repair, and economic issues.
The removal of sulfur dioxide from flue gases at coal-fired facilities results in the generation of large amounts of Flue Gas Desulfurization (FGD) material. The FGD material may be dry or wet depending on the desulfurization process. The wet scrubbing process, which is commonly used by large electric utilities in Ohio, involves the injection of a reagent (typically hydrated quicklime) into the flue gases. The wet product generated (commonly referred to as FGD filter cake) is a dewatered mixture of sulfites and sulfates of the reagent, unreacted reagent, and some water. Calcium sulfite content is typically greater than 70% while the calcium sulfate content is approximately 13%. Fly ash and additional quicklime are added to stabilize the FGD filter cake. This stabilized (fixated) FGD material is gray in color and looks like silty clay. Research conducted at The Ohio State University and reviewed by the Ohio Environmental Protection Agency (OEPA) has shown that leachate from the fixated FGD material generally meets the national primary drinking water standards. The fixated FGD material meets the "nontoxic" criteria of OEPA's Division of Surface Water.
Fly ash and quicklime-enriched FGD filter cake, when mixed at the power plant in proper proportions, will form a chemical cementious reaction that, upon adequate compaction in a fairly fresh state (moisture content of 40-55%), gains strength and durability. Quicklime-enriched FGD material is considered to be a manufactured product when produced at a generating facility. The beneficial use of quicklime-enriched FGD product for livestock feeding or hay bale storage pads is not subject to additional OEPA review when used in accordance with the statewide permit-to-install (PTI) issued by Ohio EPA (Application No. 07-0037, dated June 25, 1997).
Concrete or stone aggregate typically has been used for constructing livestock feeding pads. However, research conducted at The Ohio State University has shown that construction of pads using compacted FGD product is an inexpensive and reliable alternative. The first cattle feeding pad using FGD material was constructed in 1992 at the Eastern Ohio Resource Development Center (EORDC) near Belle Valley in Noble County. Cyclone ash from American Electric Power's (AEP) Tidd plant was used. Additional feeding (Figure 1) and hay bale storage pads (Figure 2) were constructed at the EORDC farm in 1993 using wet FGD material from AEP's Conesville plant. The success of these demonstration projects led to statewide approval of FGD pads for these two applications using AEP's lime-enriched FGD product. In the summer of 1997, twenty-four livestock feeding and hay bale storage pads, ranging in size from 1,500 square feet to 15,000 square feet, were constructed in eastern and southeastern Ohio. In 1998, more than 150 FGD pads were constructed in 12 counties in Ohio.
Figure 1. Livestock feeding pad
Figure 2. Hay bale storage pad
FGD pads may be constructed for storing hay bales (primarily large, round bales as shown in Figure 3). Appropriate pad design allows bales to be placed so that precipitation drains away from them relatively quickly. Rain and snow will collect in troughs formed by bales whose sides touch, so leave a gap between adjacent rows of bales. Drain water from the pad by either crowning the pad across its length or constructing the pad with some continuous fall toward one end; provide 1% or greater grade in either case. Side-slope should be small compared to the lengthwise grade--or water will collect along the uphill side of rows/bales. If the side-slope and lengthwise grade are similar for a site that is suitable otherwise, plan to systematically place gaps every couple of bales along each row to reduce ponding around the bales (and adjust pad length accordingly).
Figure 3. Hay bale storage on constructed FGD pad
Approach areas may be included along the perimeter of the hay bale storage--along ends of the pad if bales will be typically handled by their ends or along sides of the pad if handled by their sides (latter case shown in Figure 3)--to improve access to the bales. If used, approach areas should be wide enough to allow bale-handling equipment to access the nearest bales, including a turn, without dropping a wheel off the pad. Use concrete rather than FGD in any areas where handling equipment is likely to make frequent turns and in areas which will accommodate more than just bale-handling equipment. Material will rapidly slough off the pad surface under intensive use by equipment.
Reasonable grades must be maintained on a pad for safe operation of bale-handling equipment, especially along the length of a pad when bales are to be handled from the side. Also consider operator safety at locations associated with bale transport, such as turns in drives and places where bales are likely to be elevated. Consult manufacturer recommendations provided for your equipment before investing resources into a questionable site.
OEPA approved the statewide construction of FGD pads on June 25, 1997. A PTI (Application No. 07-0037) was issued to AEP for providing quicklime-enriched FGD product from its Conesville and Gavin power plants for the construction of livestock feeding and hay bale storage pads. As long as the conditions outlined in the PTI are followed, landowners and livestock farmers generally do not have to obtain additional authorization from OEPA. This fact sheet has been prepared to be in conformity with the PTI issued by OEPA.
The material to be used in the construction of the pads is the fixated FGD product generated at coal-fired power plants which has been enriched with an adequate amount of fly ash and extra quicklime so that the total lime content is 4-6%. Lime-enriched FGD product that has been approved for constructing pads is currently available from AEP's Conesville power plant (Coshocton County) and Gavin power plant (Gallia County). The Gavin FGD material typically has a lower moisture content than Conesville FGD material. The material is currently available free of cost at the plants. The Conesville plant may be willing to transport the material free of cost within Coshocton County.
Runoff will occur from FGD pads, just as if they were made of concrete. This runoff needs to be controlled to avoid polluting nearby waterways. Livestock feeding and hay bale storage pads constructed of lime-enriched FGD material need to be located on a farm such that a healthy farm environment can be maintained. As per OEPA restrictions, FGD pads may not be located:
Additionally, pads must not be located in areas which are identified by a soil survey as subject to flooding, or likely to convey manure runoff directly to a waterway (via a cow-path, ditch, drive, etc.) regardless of the separation distance.
Installing control structures such as catch basins, small earth dikes, etc., can accommodate many of these siting restrictions. Local Natural Resources Conservation Service (NRCS) and Soil and Water Conservation District (SWCD) personnel can assist in the planning of control structures and may be able to identify sources of monetary assistance.
If animals will be confined on a pad rather than allowed to access the pad at their leisure from a pasture to eat or drink, the area may be considered to be a feedlot and, by definition, an "Animal Feeding Operation." In order to limit the liability of producers and retain the protections of the OEPA PTI, strategies for controlling runoff from such pads need to be designed by a professional and implemented on the farm prior to construction.
The size of the FGD pad selected can significantly affect the cost and efficiency of the livestock operation. The pad should be large enough to accommodate the present animal population as well as allow for future additions to the herd as projected by the owner or operator of the facility. However, an excessively large pad can result in unnecessarily high construction costs. A livestock feeding pad should be large enough to accomodate the animals that are eating or drinking, plus about 6 feet along the perimeter to allow the animals to conveniently move to and from the feeder or waterer. A worksheet is included to size hale bale storage pads. Feeding pads should be sized in conjunction with development of a runoff-control strategy. For illustrative purposes, an FGD pad that is 100' x 100' and approximately 12"-15" thick will require 500-600 tons of FGD product.
An open pad does not usually constitute a controlled manure storage facility in Ohio and FGD product is not currently approved as a construction material for manure storage. Therefore, any scraped manure/material should be transported to a designed storage facility or to a field for application as soon as feasible.
Livestock access areas can also be constructed of FGD material if animals will regularly use the areas. An access area is defined as land which immediately surrounds a pad and will reasonably only support traffic that is directly associated with the pad. Use of FGD to construct drives, lanes, and other trafficways is not allowed under current Ohio EPA permit authority.
FGD pads need to be constructed between May 1 and August 30 to minimize potential freeze/thaw effects. This will allow the FGD material to cure for a sufficient amount of time before being exposed to freezing weather. If the FGD material is too dry or too wet, it cannot be compacted properly. The moisture content of the material during compaction should range from 40-55%. For successful installation of FGD pads, the following procedure is suggested as per the PTI issued by OEPA:
Comply with the location restrictions specified in the Pad Location section.
Excavate the site to expose the subgrade. Clear the area of any vegetation, sod, manure, organic soil, and debris.
Establish a reasonable grade for positive drainage. A maximum slope of 3-5% is suggested. Slopes in excess of 8% can cause excessive erosion of the pad.
Compact the exposed subgrade with compaction equipment (roller) or hauling equipment (loaded truck, tractor) prior to placement of FGD. If excessively weak or wet soils are encountered, remove the soil, backfill with FGD and compact.
Place FGD material within 3 days of delivery to the site (Figure 4). If the FGD material delivered to the site is too wet to be compacted, let the FGD material remain in a pile for a day and then apply it to the pad site. Spreading of FGD does not facilitate drying of the material.
Figure 4. Delivery of FGD
Spread FGD to the appropriate depth by using a bulldozer, tractor blade, or grader (Figure 5). Break large lumps using dozer tracks, tractor tires, Rototillers, etc.
Figure 5. Spreading of FGD
Add additional lime, quicklime fines, or cement to the FGD product if so desired by the owner of the facility. No additional lime needs to be added to the FGD product.
Pads should be made in layers, whenever possible, to improve pad durability. FGD material that has less than 50% moisture content (Gavin FGD material) should be compacted in three layers (up to 5 inches each) or at least two layers (up to 7.5 inches each). Due to less desirable workability, wetter FGD material (Conesville FGD) may be formed into a pad as a single layer provided extra attention is dedicated to thoroughly consolidating the material.
Compact each layer (extremely important) as shown in Figure 6 to consolidate the FGD material and obtain a uniform, solid surface. Use a smooth-drum or sheepsfoot roller or equipment with equivalent compactive effort (earthmoving equipment or heavy farm tractor). Remove any boulders of FGD that cannot be easily broken and worked into the layer.
Figure 6. Compaction of FGD
Rough up the top 1/2 to 1 inch of each layer/lift prior to the placement of the next layer to provide adequate bonding between the two layers.
Keep the total thickness of the compacted FGD pad less than 15 inches.
Smooth-roll the top layer to provide a uniform, solid surface. A 1/2-inch to 1-inch layer of gravel may be rolled into the finished surface to improve traction. If farm equipment will be operated on the pad area often, strengthen the top layer with 5% quick lime, Portland bag cement, or 15-20% lime kiln dust (added at the site).
Feather-roll (down to zero depth) the edges of the pad. Otherwise use earthen or steel edging forms.
Keep the pad surface moist for a minimum of 7 days to allow for proper curing. Cover the pad with straw or sheets of plastic.
Keep livestock off the pad for at least 30 days following the initial 7-day curing period.
Install fence posts, if needed, within 30 days of constructing the pad. Otherwise the FGD material may become too difficult to penetrate.
The two most important criteria for successful installation of an FGD pad (see Figure 7) are the moisture content of the FGD product and the compactive effort used to consolidate the material.
Figure 7. Completed FGD pad
Periodically, manure or waste feed will need to be removed from a pad. This is usually carried out using a skid loader or box scraper. Pad life is expected to depend on the amount of use by livestock and equipment. While scraping the pad, caution should be taken not to remove excess amounts of FGD. To extend a pad's life, leave a thin cover layer over the pad surface rather than gouging into the FGD when scraping the pad. Incidental amounts of FGD that are removed during scraping may be spread with the manure. The pad is expected to lose about 1/4 to 1/2 inch of FGD material every year due to these incidental losses. After a few years of service, if the top surface of the pad shows small patches or holes, repair by filling in with inexpensive ready-made cementious materials. If local failures on the top surface are extensive, then clean the surface thoroughly and put an additional layer of compacted FGD on top of the existing pad. If for any reason the pad needs to be removed from the farm, then the FGD product will become subject to waste disposal requirements and must be taken to a licensed landfill.
The cost of using the FGD product for constructing livestock feeding and hay bale storage pads compares favorably with conventional materials such as concrete or rock aggregate. Twenty-four FGD pads were constructed in the summer of 1997 in Gallia and Coshocton counties. A cost analysis was carried out for six of the FGD pads installed in Gallia County. The cost summary comparison is listed in Table 1. Estimates were prepared using cost guidelines developed by NRCS and local prices for equipment operators, materials, and transportation in the Gallia County area. On average, an FGD pad constructed in Gallia County cost approximately $2,750 with approximately half of the cost for trucking of FGD and the rest for site work and material placement. The total cost of the FGD pads was about 26% less than the estimated cost for construction using aggregate and about 65% less than the estimated cost for concrete pads. For Coshocton County, where the FGD material may be delivered free to the site by the Conesville plant, the projected savings compared with aggregate and concrete would be 63% and 83% respectively. This represents a significant amount of monetary savings for farmers installing pads using the FGD product.
|Table 1. Cost Summary for FGD Pads Constructed in Gallia County|
|Project ID||Area (ft2)||Actual FGD cost||Estimated aggregate cost||Estimated concrete cost|
|Ratio to FGD cost||1||1.36||2.86|
|FGD savings as %||26.4%||65.1%|
More information on the use of FGD product for constructing livestock feeding and hay bale pads can be obtained from the following:
For technical information, contact American Electric Power's Geotechnical Engineering Section at (614) 223-2940.
For regulatory guidance, contact Ohio EPA's Division of Surface Water at (614) 644-2025.
Construction of FGD livestock pads needs to be a part of an overall farm plan. NRCS personnel can assist interested farmers in developing a farm conservation plan. Owners and operators of livestock facilities should contact their county Extension agent, Soil and Water Conservation District, NRCS personnel and the following:
To use FGD product of AEP Conesville Plant (Coshocton County)
Bill Jewett, AEP: (740) 829-4121 or 4083
Rob Senita, AEP: (740) 829-4034
To use FGD product of AEP Gavin Plant (Gallia County)
Doug Workman, AEP: (740) 367-7331
Farmers must provide the following information at the time of placing the order for the FGD product:
The manufacturer of the FGD product shall provide to the user the following documents:
Construction of livestock feeding and hay bale storage pads using quicklime-enriched fixated FGD product is a reliable and economical solution to excessively muddy conditions in high rainfall areas such as Ohio. This fact sheet covered the characteristics of FGD material and the regulatory issues involved. It included recommendations for siting, sizing, installing, and maintaining pads as well as performance data of FGD pads. An economic analysis of pads constructed in Gallia County was presented. The inexpensive and reliable use of this material can result in significant cost savings for farm operators and owners while improving the quality of farm operations in Ohio.
More information on the uses of FGD and other coal combustion products can be obtained from the following Internet web site: http://ccpohio.eng.ohio-state.edu
or by contacting the pilot Extension program project coordinator:
Dr. Tarunjit S. Butalia, P.E.
Research Specialist: Coal Combustion Products Coordinator
Department of Civil and Environmental Engineering and Geodetic Science
The Ohio State University
470 Hitchcock Hall
2070 Neil Avenue
Columbus, OH 43210-1275
Phone: (614) 688-3408
Fax: (614) 292-3780
Permit to Install for Lime-Enriched FGD Feeding/Hay Bale Storage Pads Across the State of Ohio. 1997. Application No. 07-0037. Approved June 25, 1997. Ohio Environmental Protection Agency, Columbus, Ohio.
Beef Housing and Equipment Handbook. 1987. Midwest Plan Service publication MWPS-6. Midwest Plan Service, Iowa State University, Ames, Iowa.
Dairy Freestall Housing and Equipment. 1997. Midwest Plan Service publication MWPS-7. Midwest Plan Service, Iowa State University, Ames, Iowa.
Sheep Housing and Equipment Handbook. 1994. Midwest Plan Service publication MWPS-3. Midwest Plan Service, Iowa State University, Ames, Iowa.
Swine Housing and Equipment Handbook. 1991. Midwest Plan Service publication MWPS-8. Midwest Plan Service, Iowa State University, Ames, Iowa.
A Field Demonstration of the Use of Wet and Dry Scrubber Sludges in Engineered Structures. 1995. W. E. Wolfe and J. H. Cline. Proceedings of the 11th International Symposium on Use and Management of Coal Combustion By-Products (CCBs), Volume 1, American Coal Ash Association and Electric Power Research Institute, Orlando, Florida, January 15-19, 1995. EPRI Report # TR-104657-V1. Electric Power Research Institute, Palo Alto, California.
Heavy Use Livestock Pads Constructed of Stabilized FGD By-product. 1997. Report prepared by Gallia County NRCS and Radian Corporation. Federal Energy Technology Center, Pittsburgh, Pennsylvania.
Land Application Uses of Dry FGD By-Products: Phase 1 Report. 1995. R. Stehouwer, W. Dick, J. Bigham,
L. Forster, F. Hitzhusen, E. McCoy, S. Traina and
W. Wolfe. Electric Power Research Institute, Report # EPRI TR-105264. Electric Power Research Institute, Palo Alto, California.
Land Application Uses of Dry FGD By-Products: Phase 2 Report. 1998. R. Stehouwer, W. Dick, J. Bigham,
L. Forster, F. Hitzhusen, E. McCoy, S. Traina and
W. Wolfe. Electric Power Research Institute, Report # EPRI TR-109652. Electric Power Research Institute, Palo Alto, California.
Land Application Uses of Dry FGD By-Products: Phase 3 Report. May 1998. W. Dick, J. Bigham, L. Forster, F. Hitzhusen, R. Lal, R. Stehouwer, S. Traina and
W. Wolfe. The Ohio State University, Final Technical Report, EPRI Project RP2796-02. The Ohio State University, Columbus, Ohio.
This publication was produced through a cooperative effort between Ohio State University Extension and the College of Engineering at The Ohio State University. The technical information presented in this publication was collected through the financial support of Ohio Department of Development's Ohio Coal Development Office, US Department of Energy's Federal Energy Technology Center, American Electric Power Company, Cinergy, FirstEnergy and Dravo Lime Company. American Coal Ash Association-National and Ohio Chapter, Ohio Farm Bureau Federation, Ohio Dairy Farmers Association, and Ohio Cattlemen's Association, provided additional support.
The authors express their appreciation to the following reviewers: Greg Sanders (Ohio EPA); Arthur Brate, Michael Monnin, Robert Keen, Robert Hendershot (USDA-NRCS); Kevin Elder (ODNR); Donald Clark (Ohio Department of Development); William Aljoe (US Department of Energy's Federal Energy Technology Center); David White (Ohio Farm Bureau Federation); Stephen Boyles, Phil Rzewincki, Hal Walker, Earl Whitlach, Don Eckert, Paul Golden, Brian Strobel, Doug Clevenger (The Ohio State University); Robert Brown (Ohio Coal Development Office); Howard Humphrey, Shan Mafi, William Jewett (American Electric Power); Michael Bates (FirstEnergy); Joel Beeghly (Dravo Lime Company); Jack Cline (Hocking College); Michael Schroeder (American Coal Ash Association-Ohio Chapter). Copies of this fact sheet were also sent to the following agencies for review: Ohio Department of Agriculture, Ohio State University Extension District Offices, Ohio Cattlemen's Association, Ohio Dairy Farmers Federation, Ohio Rural Development Partnership, Ohio Pork Producers Council, Cinergy.
For more information on the use of CCPs, please visit the "CCPOhio" web page at: http://ccpohio.eng.ohio-state.edu
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-6181