Author: Amy Millmier Schmidt, UNL Livestock Bioenvironmental Engineer
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Reviewers: Todd Whitney, Nebraska Extension; Rick Koelsch, University of Nebraska – Lincoln
Manure, litter or other biosolids originating from feedlots, poultry houses, municipal waste treatment systems or industry sources are often stockpiled at the edge of a field to be readily available for land application when field conditions permit entry, such as after crops have been harvested. Selecting an appropriate place to stockpile these materials is important to minimize risks to surface and ground water and to avoid potential nuisance issues for neighbors.
The Nebraska Department of Environmental Quality regulations pertaining to manure or litter stockpiles on animal feeding operations (AFOs) are equivalent to the practices dictated for manure application on these operations:
1. FOR LARGE CONCENTRATED ANIMAL FEEDING OPERATIONS (CAFOS), manure or litter may not be stockpiled closer than 100 feet to any down-gradient surface waters, open tile line intake structures, wellheads, or other conduits to surface or ground water. A 35-foot-wide vegetated buffer between the stockpile and the areas listed above can be used as an alternative to the 100-foot setback.
2. FOR SMALL AND MEDIUM CAFOS, AND AFOS NOT REQUIRED TO SEEK PERMIT COVERAGE, manure or litter may not be stockpiled closer than 30 feet to any streams, lakes and impounded waters.
BUT WHAT ABOUT WHEN MANURE OR OTHER BIOSOLIDS ARE TRANSFERRED TO A LANDOWNER OUTSIDE THE ANIMAL FEEDING OPERATION, MUNICIPALITY OR OTHER SOURCE OF THE MATERIALS?
While NDEQ regulations pertaining to manure management on AFOs and CAFOs do not extend to manure or litter that is transferred to someone “outside” the operation, that should not be interpreted to mean that careful management of the material is not still prudent. The following recommended practices include criteria listed in the Natural Resources Conservation Service Conservation Practice Standard Short-term Storage of Animal Waste and By-products, Code 318 (available at: https://tinyurl.com/y78s9k7w). Please keep in mind that individual counties may employ additional restrictions beyond those listed here.
STOCKPILE ONLY WHAT IS NEEDED FOR THE INTENDED APPLICATION AREA. When receiving biosolids from a neighboring farm, municipality or other source, a nutrient analysis report should accompany the material. If not provided, a sample of the material should be submitted for nutrient analysis. Use this nutrient data to determine an appropriate land application rate and only stockpile as much material as the available land can accommodate. Excess application may contribute to nutrient and sediment runoff losses while excess nutrients represent unrealized fertilizer value that could have been used elsewhere.
AVOID WATERWAYS AND LOW-LYING AREAS. Do not stockpile biosolids on grassed waterways or where water tends to pond or concentrate during precipitation events. Instead, choose an area that is “high and dry” and that does not drain towards a nearby water body or property boundary.
PREVENT AND MANAGE RUNOFF. Leachate (liquid seeping from the piled material) and storm water coming into contact with the stockpile must be handled to prevent runoff from reaching neighboring properties or water bodies. Covering the pile with a tarp can help prevent runoff. If left uncovered, runoff from the stockpile area can be managed with an earthen berm or dike, grassed buffer area, and/or silt fence. When using a grassed buffer area, at least 30 feet of vegetative buffer (35-feet minimum for large CAFOs) on the downslope side of the stockpile storage area is recommended for filtering solids in the runoff. Assess the site for the potential for runoff to create channel flow. If channel flow occurs, a 30- to 35-foot buffer will not be effective.
AVOID STEEP GRADES. Land with a slope greater than 3% should not be used unless a structure or practice is in place to prevent runoff from the stockpile area.
BE CONSIDERATE OF NEIGHBORS. Choose a location for the stockpile that is as far as possible – but at least 100 feet – from neighboring land owners, roads, or other sensitive areas to minimize the risk of neighbors experiencing odors and flies that could be associated with the stockpile.
MINIMIZE ODOR TRANSPORT. Placing a stockpile where neighbors or other sensitive areas (roads, public use areas, etc.) are directly “downwind” should be avoided. A good way to determine where odors from the stockpile are most likely to travel is by consulting a wind rose for your location.
An example wind rose for Lexington, NE during October can be viewed at http://go.unl.edu/wjd6. Based on this wind rose, when considering where to stockpile manure or biosolids near Lexington this fall, a preferred site would be one with minimal neighbors or other sensitive areas to the north of the stockpile, particularly if they are relatively close to the field where the material is being piled. For a field with neighbors or a road directly to the north, it would likely be best to place the pile as far south in the field as possible while still accounting for the other recommended practices described in this article. To generate a wind rose for a location, the High Plains Regional Climate Center (https://hprcc.unl.edu) offers a tool accessible from their website under “Services” at the top of the page. Click on “Online Data Services” and scroll down the page to the box titled “Wind Roses”. Selecting this tool will open a page where a state, station location, and timeframe can be selected to generate the associated wind rose.
PROTECT WATER AND SENSITIVE AREAS. Choose a location for the stockpile that is:
a. at least 100 feet from wells, springs, streams, and ponds;
b. where the seasonal high water table will be no closer than four feet below the bottom of the stored material, unless a geosynthetic liner is used;
c. on soils that are not likely to permit leaching of nutrients. Soils with higher sand content should be avoided unless the material is placed on a compacted soil pad, geomembrane lined pad, or similar leachate barrier and the stockpile is covered;
d. where there are no groundwater spring, seep, or subsurface drainage tile lines that could be contaminated by the stored waste; and
e. “high and dry,” where runoff will not channel.
Remember, stockpiling of manure or other biosolids should be a temporary storage method. A good temporary site will avoid neighbor nuisances, maintain good separation between the stockpile and both surface and ground water, and store biosolids for the shortest time possible.
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Stockpiling Manure and Biosolids
Author: Amy Millmier Schmidt, UNL Livestock Bioenvironmental Engineer