Runoff prevention is one of the many considerations when constructing a new prefabricated metal building on your farm. This conservation practice isn’t just about keeping water from puddling around the entrance — it ensures the quality of local and regional watersheds and keeps soil from eroding. Here we’ll explain why the National Resources Conservation Service (NRCS) funds runoff control and describe the building practices you can employ so your agricultural building ensures the protection of water and soil resources.
Why runoff control is important
Fertilized soils and waste from livestock are significant sources of nutrient runoff. But for the purposes of preventing runoff from an agricultural building (where livestock or their waste is often stored), we’ll be looking specifically at feedlot and barnyard runoff and the ways to prevent it.
When it rains and water runs off of your livestock housing or waste storage facility, surrounding sediment and the nutrients in the waste don’t stay put. The water-soluble contaminants (nitrogen, phosphorous) can be transported to clean water in surrounding streams, rivers and lakes, which can have far-reaching effects on the biological status of aquatic systems and water quality. Also, movement of sediment can cause soil erosion and lower soil quality on the farm.
To maintain water quality and prevent soil erosion, the NRCS funds runoff control practices for farmers. With the NRCS’s National Water Quality Initiative (NWQI), the program has prevented loss of over 700,000 tons of sediment, over 1.8 million pounds of phosphorous and nearly 8.5 million pounds of nitrogen loss.
Returning focus to your metal building, you can add to these successes by enacting farm runoff prevention conservation practices on your livestock housing and waste storage facilities.
Agricultural runoff solutions
Agricultural runoff solutions for a prefabricated metal building fall into two categories: Structural practices that apply directly to the construction of the metal building, and non-structural practices. The NRCS often recommends these practices together as part of a larger runoff prevention system. Most of the following practices are supported by funding from the NRCS through the Environmental Quality Incentives Program (EQIP) or the NWQI, but can also be implemented voluntarily with support from your local NRCS office.
These practices directly apply to the construction process of your metal building and should be integrated into the specification for the building along with the standard steel building features.
Roof runoff structure
This practice involves adding gutters, downspouts and ground gutters to control rainwater as it comes off of your building’s roof. The water can be diverted away from contaminated areas, or it can be captured for livestock watering and irrigation. The NRCS practices specifies gutter design, materials and maintenance plans to best control runoff. For example, the gutter’s capacity must be able to convey the flow rate generated from the 25-year, 5-minute rainfall event. For the full specifics of the practice, click here.
Building with topography in mind
Farmers should understand where water naturally flows on their property when deciding where to place a new metal building. According to Purdue University, a common mistake is not elevating the floor level of a new facility high enough above the outside grade to prevent runoff ponding. They recommend the floor of your facility should be at least 12 inches above the outside grade.
Topography also plays a role in the selection of the other practices. For instance, if your farm is relatively flat, you may choose not to use a roof runoff structure because the gutters would then create a concentration of water over a small area. Every farm is different, and thus the practices used on it should be specific to its topography.
Foundation best practices
When constructing a new metal building, a general contractor will usually use a local concrete engineer to design the foundation. These experts already follow codes on ensuring the foundation doesn’t affect the flow of water on a property, so continue as usual with the foundation for the new metal building and it should not cause additional runoff issues.
The NRCS recommends anywhere from 3 to 15 practices in conjunction to achieve a resource conservation goal — in this case, the goal of protecting water and soil quality. Here is a brief overview of the non-structural practices.
- Critical area planting Establishing permanent vegetation in areas expected to have high erosion rates.
- Grassed waterway A channel with enough vegetation that water flows through at a non-erosive rate, then is conveyed to a suitable outlet.
- Filter strip: Similar to a grassed waterway, but this area of vegetation removes the contaminants (nitrogen, phosphorous) from flowing water.
- Vegetated treatment area: An area where vegetation is used to reduce the contaminants in a standing area of water.
- Transfer: Using pipe or conduits to move waste to a storage facility and keep it from infiltrating local waterways.
- Storage facility: Where the waste is stored — either an embankment, pit or a structure. For example, dry chicken waste is stacked in a structure. If the waste storage facility is a structure such as a metal building, the structural runoff practices can apply as well.
- Separation facility: Water containing waste can be conveyed to a separation facility, where a filtration device, settling tank, settling basin or settling channel is used to separate nutrients from the water.
- Underground outlet: A conduit or system of conduits installed underground to move surface water to an outlet.
- Water harvesting catchment: Prevents runoff from carrying nutrients across the farm by catching and storing the water. It can then be used to provide water for livestock. To calculate the approximate amount of rainfall from your roof, use this equation from Iowa State University.
Using any number of the conservation practices will ensure your farm plays a role in protecting soil and water resources for you and your neighboring farmers for generations to come.