2010 Issue

22 Manure Management of Hog Wastes KIRAN L. BHAYANI, P.E., D.EE ., F.ASCE EDWARD P. HICKEY, PG I T HAS BECOMEMORE SPECIALIZED than gener- alized traditional operation. Animal breed- ing to raising to market weight nowadays occur in one group or operation. n early nineties, Smithfield Foods, Prestage Farms and Carroll’s Foods from North Carolina, looked to Milford in Beaver County, Utah, for siting a producer network, Circle Four Farms, for fast access to the West Coast market, with a goal of 120,000 female pigs (sows). This project has added $ 120 million in assets and $8 million in payroll or about 400 jobs in Beaver and Iron counties in Utah. Notwithstanding an efficient industrial opera- tion, the project has brought into focus odor and manure management issues. Desert cli- mate of Milford, allows manure management Changing times – primarily advances in animal genetics, technology and management practices - have brought about a dramatic shift from traditional family farms to a corporate and industrial type structure in pork production nationally. through a system of primary – anaerobic for stabilization of organic matter in the manure, and secondary - facultative for evaporation of effluent, lagoons. The lagoons are lined with a 40-mil high-density polyethylene geomem- brane. Circle Four Farms has also constructed collection basins adjacent to the existing la- goon systems and a Central Treatment Plant approximately ten miles west of Minersville, Utah. In brief, 17 sow, 14 nurseries, 33 finisher and one stud farm, facilities are served by cor- responding lagoons holding 1.7 billion gallons of hog manure. Figure 1 gives an overview of the Circle Four operation in Beaver and Iron counties. Other countries have alternative treatment processes to manage hog manure. Economics and climate were major factors in selecting lagoon for waste management. Engineering for Lagoons The primary lagoon at each farm site is designed to operate as an anaerobic waste treatment lagoon in which liquid and solid swine waste, flushed from the pits under the animal contain- ment barns, is digested primarily by anaerobic bacteria in the treatment volume of the lagoon and sludge accumulates in the bottom. These design specifications require the establish- ment and maintenance of a properly balanced bacterial population, which is realized through the proper operation, and management of the anaerobic lagoons. Good operation and man- agement of anaerobic lagoons will also optimize volatile solids digestion and prevent excessive sludge build up extending the effective life of the lagoon before sludge removal becomes necessary. Only wastes from the hog-raising operations are allowed for discharge to the lagoons. The design, operational, and contin- gency requirements detailed herein represent the best available technology, since the imple- mentation of these requirements is expected to be protective of ground water resources in the area surrounding the facility based on the avail- able information and knowledge base currently. Lagoon Design Criteria Farm sites each have at least one primary lagoon and a containment basin for evaporation. The lagoon system is sized to accept up to 1.8 cubic feet of volume per live animal weight in the primary lagoon for sow and finisher farms (2.3 cubic feet for nursery farms) and provide enough surface area for evaporation of water in the con- tainment basin. Primary lagoons and contain- ment basins are lined with a 40-mil high-density polyethylene geomembrance or compacted clay with hydraulic conductivity of 1.0 x 10-7 centimeter per second. Hydraulic conductivity of 40-mil high-density polyethylene is typically 2.7 x 10-13 centimeter per second. (Haxo, H.E., and Layey, T.P., 1988. Transport of DissolvedOr- ganics from Dilute Aqueous Solutions Through Figure 1 – Overview