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 Animal Waste Management Systems . Waste management systems, practice 312, serve to
collect, control, and treat waste from confined animal lots such as feedlots and barnyards. The purpose
is to minimize pollutant runoff and to conserve nutrients for crop production. Feedlot and barnyard
runoff practice standards are developed to provide planning tools to prevent the discharge of animal
waste directly into waterways.
Diverting tributary or upland runoff water away from concentrated animal areas reduces nutrient
runoff and can improve conditions for waste handling. Dikes, diversions, earthen berms, ditches, or
inlets and drains may be used to divert tributary flows. Relocating a barnyard away from a watercourse
may be necessary to meet water quality goals. Fencing may be needed to exclude cattle from a
watercourse except when a stream crossing is necessary.
Livestock should be kept in a designated area to facilitate the collection of manure and to
protect water diversion structures. A scraping schedule should be determined for removal of lot
manure. Curbs may also be necessary to control manure and divert it to collection locations.
Contaminated runoff and seepage should be stored for treatment, disposal, or use on cropland.
Robillard et al. (1983) found the diversion of upland flows, the collection and diversion of roof
water and the interception and diversion of subsurface flows from two barnyards reduced total
phosphorus export by 80%. BMPs reduced transport of nutrients by reducing flows while nutrient
concentration remained essentially unaffected.
Upland diversions and roofing reduce manure contact with precipitation and decrease
transport. Young et al. (1982) determined that overland flow from upland, tributary areas, passing
through the feedlot can become sufficiently mixed within and approach the same pollutant
concentration.
Treatment for feedlot, barnyard or milkhouse waste not applied to cropland must be carefully
designed in consideration of hydraulic loading. One system for treating animal lot runoff is a settling
basin to trap solids and dissolved pollutants followed by vegetative treatment (e.g. filter strip, grassed
waterway) to further treat effluent. Settling basins reduced ammonia nitrogen concentration by 40%.
(Miner et al. 1981) and total nitrogen and total phosphorus by 35-40% (Edwards et al. 1983).
Filter strip treatment of barnyard and feedlot waste can be quite variable. Meals (1987) found
significant reductions in nutrient concentrations only during the growing season. Only annual subsurface
output of total phosphorus was significantly different from inflow concentrations. Total phosphorus mass
reductions were 12% and total nitrogen reductions were 15%. Meals (1987) reports high hydraulic
loading rates may have been part of the reason for poor performance. Willrich and Boda (1976) and
Walter (1983) also report decreased treatment efficiency at high loading rates. Channelized flow
decreases contact time and performance.
4.2-14
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