Septic systems/leach fields – Septic systems and leach fields are typically low in cost but are not generally suitable for treating large volumes of milking center or other process waste waters. Leach fields are easily clogged with overflow of suspended milk solids.

Vegetative filter areas – Vegetative filter areas are more costly but are reasonably effective in treating process wastewaters, providing certain design and maintenance criteria are met. Some examples of these criteria include settling and screening out solids and large organic debris, using effluent distribution methods that provide sheet flow across the entire filter area, sizing the filter area appropriately based on hydraulic loading and nutrient loading and removal criteria, and locating the filter area on suitable soils that can absorb, adsorb, and process the nutrient loads.  For milking center waste water, it's important to settle out the suspended solids first, and provide good effluent distribution on soils that adsorb phosphorus. For silage leachate collection and treatment systems, the highly concentrated effluent should be diverted or diluted to avoid vegetation kill zones in the filter area.

Aerobic lagoon – The advantages of an aerobic lagoon are to provide storage and disposal flexibility, they may use less land around the facility for treatment, there may be opportunities for liquid recycling, wastewater treatment becomes a part of the nutrient management plan when the effluent is removed, and they often entail lower labor needs and operating costs. Disadvantages of an aerobic lagoon are offensive odors may occur, aeration may be necessary, overtopping may occur (or effluent and sludge removal may need to be more frequent, especially if undersized), and the potentially high volumes of storm water runoff from barnyards and feed storage areas often necessitate an increase in size and cost.

Organic filter beds – Organic filter beds are suitable for small wastewater volumes and are quite effective at removing ammonia-N. However, they may actually release P as the organic filter media decomposes. The main disadvantages of an organic filter bed is the cost is generally prohibitive to treat large runoff volumes and the organic media beds need to periodically be replaced as they decompose. In New York, organic media beds are no longer being recommended because of their unpredictable performance and high maintenance requirements.

Constructed wetlands – The advantages of constructed wetlands are they are capable of providing a high level of treatment, inexpensive to operate and largely self-maintaining, can handle variable loadings, and they may reduce the amount of land needed for land application. The disadvantages are the direct inflow of concentrated process wastewaters may kill vegetation (hydrophytic plants are quite sensitive to high ammonia levels), large influxes of runoff induce large changes in water levels, thus reducing treatment reliability, and they may require water inputs during non storm events. Furthermore, constructed wetlands require a single dedicated land use, can potentially harbor mosquitoes and generate offensive odors, and are often more expensive to construct than other treatment options. Because of these disadvantages, other pre-treatment facilities (e.g., low flow collection, surcharge storage) are usually still needed.

Stone filled trench – The advantage of using stone filled (infiltration) trenches is simplicity, but they are not generally suitable to accepting large volumes of process wastewater without being prohibitively large or being constructed in highly permeable, well drained soils, in which case there is potential for groundwater contamination. Stones are not particularly effective at P adsorption. When saturated conditions occur in the trench, septic and odorous conditions arise, and high inputs of organic materials may quickly clog areas of the trench.

Lime Flocculation – Lime flocculation is primarily a treatment method for treating and removing P from small volumes of milking center waste. Lime flocculation is not very effective at treating large volumes of other process wastewaters. The lime chemical input costs can be high, and the residual flocculated sludge must still be properly disposed.

Spray irrigation – The advantages of spray irrigation are large wastewater volumes are easily handled, it's the best method of distributing wastewater over large areas for effective nutrient removal and retention, and it can provide needed crop nutrients as part of a nutrient management plan. The disadvantages to spray irrigation, especially in the Northeast, are the wastewater likely needs to be stored for application during dry periods and it may be difficult and not acceptable to use during winter periods. With spray irrigation, any concentrated effluents may burn or contaminate vegetation, and these systems require pumps, a network of pipes, and pumping energy inputs.

Aerobic septic system – The aerobic septic system is similar to a regular septic system except that the effluent is decomposed and treated aerobically rather than anaerobically. An advantage of an aerobic septic system is the treated effluent is of better quality for land application or disposal to the leach field, so a leach field is less likely to plug. Thus, the aerobic septic system may be better suited to sites where an ordinary septic system and leach field would fail. Some disadvantages of the aerobic septic system are that it is more expensive to construct than a traditional septic system, and it's not generally practical for large wastewater volumes.

Inclusion in liquid manure handling system – When process wastewaters are added to the liquid manure handling system, which most often uses the aerobic lagoon approach discussed in 3 above, the lagoon needs to be increased in size to handle the additional wastewater volumes.

Silage leachate is acidic (pH around 4), and contains high concentrations of BOD, ammonia-N, phosphorus, potassium, and organic carbons. Silage leachate is one of the most environmentally contaminating wastes produced on a livestock farm if it's not contained, treated, and disposed of properly. Any direct discharges of concentrated silage leachate to streams lead to rapid deoxygenation and a decrease in pH, potentially killing fish and other benthic organisms. The direct discharge to vegetated areas kills the vegetation and causes septic odors. Silage leachate is corrosive to steel and concrete, which further complicates managing this waste.

Humid climatic conditions exasperate the production of silage leachate. On an equal mass basis, grass ensilage produces more fermentable leachate than corn because of the finer chop size and higher moisture content at harvest. However, compared to corn, grass ensilage is usually put into storage at a denser pack during summer months, so less total leachate runoff tends to escape during rain events.

Management factors to reduce leachate volume and runoff from silage bunkers are to harvest crops at maturity and drier moisture content, avoid filling during rainy periods, and to cover the bunkers as quickly as possible.

Low volumes of highly concentrated leachate should be collected and diluted prior to land application.

This is commonly done by adding small amounts of leachate to dry manure prior to disposal with a spreader, or to transfer the low flow to the manure lagoon for later spreading. Silage leachate that has been diluted with storm water runoff can be either added to the manure storage lagoon, or when concentrations are acceptable, the wastewater can be diverted to appropriately-designed vegetated filter areas or perhaps be applied directly to crop fields.

The primary management objectives for improving a barnyard are to enhance livestock health and to make the care and feeding operations more efficient. Environmental objectives are to reduce offensive odors, improve facility aesthetics, and to minimize any off-site loss of contaminants that may impair water quality.

Cattle in a lot with excessive manure buildup

Photo courtesy of NRCS

http://photogallery.nrcs.usda.gov

Excluding clean water from barnyards and livestock areas reduces the potential and the volume of water that may become contaminated and flow off-site from the livestock production operations. Typical approaches to excluding clean water include the collection and diversion of rainwater from roof areas and the diversion of adjacent (upslope) in-coming runoff water around the barnyard, feedlot, and other feed and manure storage areas.

An advantage of an earthen, permeable barnyard surface is that it may infiltrate and retain contaminants in place. However, if the area is permeable, groundwater may become contaminated.

Generally, livestock traffic quickly turns earthen surfaces into seas of mud or compacted soil, from which animal health and runoff water quality soon deteriorate. Smooth concrete surfaces are easily to clean, but will quickly result in surface runoff and contaminated surface runoff if not kept absolutely clean. Slightly roughened minimally sloping concrete is best for animal footing. The roughened surface is more difficult to keep clean but has the ability to retain small amounts of precipitation without generating runoff.

Concrete cattle lot

Photo courtesy of NRCS

http://photogallery.nrcs.usda.gov

Barnyards should be constructed and established so that cleaning can be easily and efficiently accomplished without leaving residual deposits, especially in areas where the residuals would impede rainfall runoff or runoff collection devices. Barnyards that are cleaned frequently improve animal health, are easier to clean, and reduce concentrations of contaminants in any runoff. Barnyards are sloped to runoff collection chambers, and concrete curbs are usually installed to which cleaning equipment can push against. Barnyard runoff treatment options are to collect and transfer the effluent to a manure storage lagoon, or to utilize a series of screens and settling tanks to remove suspended materials and digestible solids, and then to transfer the runoff effluent to a vegetated filter or other treatment area.

Considerations should be given to limiting the size of barnyards, eliminating them altogether, or placing a roof over them to minimize or prevent the amount of contaminated runoff water that is generated. The real need and purpose for a barnyard should be addressed, as barnyards may not be necessary.

Smaller travel ways can perhaps be used to move livestock between the milking parlor and the pasture, or other feeding and holding areas. Wastewater treatment strips may be very difficult to build for barnyards in some areas because of limiting site conditions and current standard (regulatory) requirements.

Concrete-lined manure storage pit with push-off slope

Photo courtesy of NRCS

http://photogallery.nrcs.usda.gov

• Dairy farms in particular represent a large source of potential nutrients and contaminants. Management of these sources – milking center waste, manure, bedding, silage, etc – must be carefully managed.
• Any barnyard can contribute to pollution or water contamination, so practices to improve barnyard cleanliness and reduce the risk of runoff are essential.