Manure spill prevention and management
Manure spills and leaks can cause adverse environmental impacts such as pollution of surface and groundwater. Excess nutrients in surface waters can cause harmful algal blooms that deplete water oxygen and produce toxins. Nitrate in groundwater can cause a condition in infants that limits oxygen supply to the blood. Manure pathogens that enter waterways can infect people and animals that come in contact with them.
Manure spills are costly, time consuming, and harmful to the environment, so the main goal should be to prevent leaks and spills wherever possible. The most common sources of manure spills are during:
- Land application
Preventing spills from manure storage
Most manure spills in liquid storage occur from pit/lagoon overflow or damage. Monitor and pump pits and lagoons before they reach the level where a large rain event could cause overflow. Installing a liquid level marker/gauge is a good way to monitor pit/lagoon depth since it will indicate when storage is getting too full (Figure 1). Inspecting pits and lagoons for any rodent or erosion damage will also help prevent spills or leakage. Fix any damage found immediately so that the problem does not worsen.
For stockpiled solid manures, a large rain event could cause significant runoff. To avoid this, make sure to stack the pile so that it has a peak at the top. Once a crust is formed, this will help to shed the water (Figure 2). If the stockpile is on a slope, create a berm or ditch upslope of the pile so that water does not flow directly into the pile. Downslope, create a holding pond for any runoff water that comes off of the pile.
Preventing spills from manure transportation
The most common causes of manure spills during transportation are overloading, blowing wind, and mechanical failure. Hauling smaller loads and/or covering loads can help minimize the first two issues. Mechanical failure may occur due to breakage or malfunction of the pump, pipe, or hose connection. Before pumping, check equipment for blockages that can cause a pipe or hose to rupture. During pumping, monitor all equipment for leaks. Monitoring line pressure while pumping will help indicate if there is a blockage or leak; there might be a blockage if the pressure increases too much, and there might be a leak if the pressure decreases too much.
Address any leaks or blockages as soon as you find them. Stop pumping, and close valves to minimize the amount of manure spilled. Then, repair any leaks and unclog blockages before proceeding.
Preventing spills from manure land application
Manure spills during land application involve manure and nutrient runoff leaving the intended application area. This can happen when manure is applied at a rate higher than what is needed, or when manure is not incorporated into the soil. Manure may be applied at an excessive rate when calculation errors are made, and when all other nutrient sources are not considered. Manure cannot be incorporated into frozen ground, so avoid winter applications.
To avoid spills during application, growers should make sure they are applying at the correct and recommended rate. This can be done by accurately accounting for any other nutrient sources, and by testing soil and manure nutrient concentrations. Also, applying and incorporating manure on fields with minimal slopes will help reduce runoff risk.
Managing manure spills
Though prevention is the best way to manage spills, it is also important to know what steps to take if there is a manure spill. Just because a spill does not come in immediate contact with a waterway does not mean it is not significant. Manure and excess nutrients will eventually migrate to a nearby waterway if not properly dealt with.
Each livestock operation should develop an Emergency Response Plan to deal with situations that might arise, such as a manure spill. Review this plan and update every 6 months. An emergency response plan is required for application to the National Pollutant Discharge Elimination System (NPDES) or State Disposal System (SDS) feedlot permit coverage. Find the plan template on the Minnesota Pollution Control Agency (MPCA) website.
Follow the four C’s of manure spill response:
- Clean up
Controlling the source of the manure spill should be the first priority. Turn off any pumps or valves that may be contributing to the spill.
The next priority is to contain the spill. Build soil berms and block downstream culverts to curtail the movement of the spill, focusing on environmentally sensitive areas such as waterways.
Next, comply with regulations by contacting the appropriate agencies. Notify the local sheriff’s office if the spill affects a public road, and state law requires an immediate call to the Minnesota Duty Officer at 1-800-422-0798 and report the following:
- Operator’s contact information
- Location, date, and time of spill
- Type and amount of spill
- Any surface water or field tile that may be affected
- Steps that were taken after the spill, and what yet needs to be done
Finally, clean up the spill to the best of your abilities as soon as possible. Remove all manure and affected soil, and spread it on agricultural land at recommended rates or place in stockpile storage. As much as possible, restore the spill area to its original state.
Document all spills and keep with operation records. With diligent inspections and maintenance work, livestock operations will minimize their risk of manure leaks and spills. However, it is still important for operators to have a plan in place in case of a spill.