ID

442-909

Authors as Published

*Overview of the Virginia Farm Assessment System

Table of Contents

Introduction
I. Long-Term Storage
II. Short-Term Storage
III. Waste Storage Location
IV. Lining Materials on Lagoons, Detention Ponds, or Storage Pits
V. Land Application of Manure
VI. Abandoned Pits
Contacts and References
Glossary No. 9
 Worksheet 9

 

Introduction

Storage of livestock wastes involves accumulating manure and wastewater in an environmentally sound manner until they can be applied to land or otherwise utilized. Manure storage facilities allow farmers to spread manure when conditions are right for nutrient use by crops. Storing manure in a concentrated area, however, increases risk to the environment and to human and animal health. Fecal bacteria in livestock waste can contaminate groundwater, causing such infectious diseases as dysentery, typhoid and hepatitis.

Livestock wastes if not properly managed can become a source of nitrate and disease-causing organisms to both surface water and groundwater. Nitrate-nitrogen levels above 10 milligrams per liter (mg/l; equivalent to parts per million for water measure) can pose health problems for infants under 6 months of age, including the condition known as blue baby syndrome (methemoglobinemia). Young livestock are alsosusceptible to health problems from high nitrate-nitrogen levels. Levels of 20-40 mg/l in the water supply may prove harmful, especially in combination with high levels (1,000 ppm) of nitrate-nitrogen from feed sources.

Dry manure can be stored in solid form in stockpiles, and liquid manure can be stored in tanks or earthen basins, or stored and treated in anaerobic lagoons. Manure storage facilities, if not designed or managed properly, can be potential sources of nitrate leaching to groundwater. For example, facilities for liquid manure storage sometimes leak or burst. Seasonal filling and emptying of earthen manure storage pits can cause damage to the organic and physical seal on the bottom and sides of the pit. Short-term solid manure storage and abandoned storage areas can also be sources of groundwater contamination by nitrates.

Regulations of the Virginia Department of Environmental Quality/Water Division (DEQ) apply to storage locations and to minimum standards for seepage control from storage/treatment facilities.

The environmental safety of storing large amounts of manure in one place for an extended period depends on the following:

  • location of the storage site with respect to physical and chemical characteristics of the soil.
  • subsurface geologic materials.
  • design and construction of the storage site or facility including control of seepage.
  • proper land application and utilization of the manure once it leaves the storage site or facility at a rate and time compatible with nutrient uptake by crops.
If improper animal waste storage causes water contamination, the DEQ can impose a fine and require corrective measures.

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I. Long-Term Storage

Livestock wastes can be stored long-term (for 180 days or more) either in solid, semi-solid or liquid form.
  • Solid storage facilities use walls and slabs for stacking of heavily-bedded manure.
  • Semi-solid storage facilities use pumps or scrapers to move manure into containment areas and may separate solids from liquids.
  • Liquid storage facilities hold manure in tanks, pits or bermed areas.
Liquid and semi-solid storage systems are self-contained. Groundwater contamination can occur if the facility is not structurally sound, allowing waste materials to seep through the soil. A threat to surface water exists if pits are not emptied frequently enough to prevent wastes from flowing over the top of the structure. Liquid storage systems require the use of pipes and/or pumps for moving wastes from the barn to the storage structure. These must be carefully installed and maintained to ensure that they do not leak. Each time a pit is emptied, carefully check steel and concrete structures for cracks or the loss of watertight seals. If any breaks are apparent, repair them immediately. Likewise, check the bottom and sides of earthen waste storage pits and lagoons to be certain the liner materials have not been eroded away by agitation and pumping. Fine textured soil materials become "self-sealed" to a limited degree through clogging of soil pores. However, this seal can be destroyed through mechanical cleaning processes.

After a period of years, weathering, wave action, or wetting and drying cycles may cause the side walls of earthen pits to crack and erode, allowing wastes to seep into the underlying soil or subsurface geologic material. Groundwater contamination will result if the subsurface materials do not prevent leaching of contaminants.

While seepage from earthen waste storage facilities is not always easy to recognize, there are some tell-tale signs:

  1. A properly designed structure has the capacity to handle wastes from a specific number of animals for a known number of days. For example, if a pit or pond is designed for 180 days of storage and has received designated waste amounts, but has not needed pumping for a year or more, the structure is probably leaking.
  2. Evaporation from a liquid manure storage pit is minimal if a crust is formed. If additional liquids need to be added before the pit can be agitated and pumped, the pit may be leaking.
Some facilities for storage of semi-solid manure are designed to allow seepage from the waste stack. In these instances, the structure design must include collection and treatment of the wastes that seep out. These systems should not be considered on sites with coarse-textured soils, fractured bedrock, karst formations, or shallow water tables. The best way to handle seepage is to channel it into a watertight holding pond or storage tank.

If construction of a holding pond or concrete/steel tank is not feasible, another option is to build a covered semi-solid manure storage structure to protect the manure stack from precipitation. Roofed storage systems require adequate bedding to absorb and retain the liquid portion of the waste.

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II. Short-Term Storage

Short-term storage (usually 60-90 days and in some cases up to 180 days) is an important option available to farmers. It allows the farmer to hold livestock wastes during periods of bad weather when daily spreading may not be feasible, when land to be planted in crops is not available for applying manure, or when there is a shortage of crop acres to accommodate daily hauling and spreading of manure without the threat of runoff.

Short-term storage, which is restricted primarily to solid or semi-solid manure, has the disadvantage of requiring that the manure be handled often. Designs are available for short-term storage structures that facilitate handling and provide effective protection for surface water and groundwater.

Short-term storage systems may be applicable for those operations, such as small dairies, which often have to stack manure in fields, particularly during periods of bad weather or between cropping cycles. Field stacking is not a recommended practice. No matter how it is done, it may pose a contamination threat to surface water and groundwater. If manure is frequently stacked in fields, cover it with plastic sheets or consider constructing a short-term runoff detention pond at the storage site.

Likewise, many farmers and livestock feeders will scrape manure into piles in the open lots as temporary storage during bad weather or busy work periods. Mounds are constructed from dry manure materials that are shaped to accommodate cattle comfort. Regulations governing milk production require frequent manure collection and removal and do not allow milking cows to come in contact with stacked manure.

Many farmers have open housing for young livestock, such as pole sheds, where wastes are allowed to accumulate for extended periods of time. Roofs on these structures keep rain and snow off the manure. These structures are relatively effective for water quality protection if they are isolated from surface water runoff, and if adequate bedding is provided to absorb liquids in the wastes. To minimize water quality impacts, provide adequate bedding to reduce seepage, and clean these sheds as frequently as possible.

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III. Waste Storage Location

The location of livestock waste storage in relation to water wells or springs is an important factor in protecting the farm water supply. For temporary manure stacks and earthen storage facilities, the minimum separation distance for wells in Virginia is 150 feet.

Minimum separation distances regulate new well installation or the distance from existing wells to new waste storage facility construction. Existing wells are required by law only to meet separation requirements in effect at the time of well construction. However, for your own benefit make every effort to exceed "old regulations," and strive to meet current regulations whenever possible.

Observing these separation distances when siting a new facility is a good way to help protect your drinking water. Locating manure storage sites or facilities downslope from wells or springs is also important for protection of your water supply. (For more information about separation distances, and how the condition of your well or spring might affect the potential for contamination, see Fact/ Worksheet Sheet No. 2, Well and Spring Management.) Depth to seasonal high water table or fractured bedrock, along with soil type at the waste storage location, is another important factor. These characteristics are described in Fact/ Worksheet No. 1.

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IV. Lining Materials on Lagoons, Detention Ponds, or Storage Pits

The Virginia Department of Environmental Quality has responsibility for implementing water quality regulations that govern confined, concentrated livestock operations. In order to protect groundwater from seepage from manure storage facilities, lagoons and holding ponds, DEQ regulations require that all waste retention facilities be constructed of compacted or in-situ soil materials at least 12 inches thick and with a maximum permeability rating of 0.0014 inches per hour. Synthetic liner materials must be of at least 20 mils thickness. If these standards for lagoons and manure holding facilities are met, combined with the benefit of self-sealing caused by manure storage, groundwater can be adequately protected.

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V. Land Application of Manure

Use of manure in combination with row crop production and improved pastures is designed to remove accumulated nutrients through the cropping system. Animal waste is a valuable fertilizer and soil conditioner. When managed properly, the nutrients in manure can be substituted for commercial fertilizers while saving money and protecting groundwater and surface water.

Solid manure can be incorporated by tillage immediately following its application, and liquid manure slurry can be injected into the soil. Manure application should be applied near the time that planting will occur to maximize nitrogen uptake by crops and minimize the loss of nitrogen through runoff or leaching through the soil profile. Liquid manure and lagoon effluent can also be applied to land areas by irrigation over growing crops. Care must be taken, however, to prevent burning of some plants by the waste materials and to avoid excessive runoff.

Stored manure, prior to land application, should be sampled and tested to determine how much nitrogen, phosphorus and potassium it contains. When sampling manure, be sure to obtain as representative a sample as possible. This usually involves taking a number of subsamples (e.g. 10 or more) and mixing the subsamples into one or more combined samples to be analyzed. This information, along with a knowledge of the amount of manure applied per acre, enables a farmer to determine whether or not additional commercial fertilizer is needed to meet crop production goals. A farm nutrient management plan will take all of these factors into consideration.

Land application should not be carried out during extended periods of bad weather which make application impractical or illegal. Virginia Department of Environmental Quality rules discourage application of wastes when the ground is frozen or saturated.

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VI. Abandoned Pits

Abandoned waste storage pits, especially earthen ones, can pose significant water quality as well as safety problems. Any abandoned structure should be completely emptied and the contents utilized. In the case of earthen waste storage facilities, liner materials (to a depth of about two feet) should be removed and spread over croplands. The remaining hole should be filled and leveled. Manure packs from pole barns or sheds no longer in use should also be removed and the wastes applied to cropland. If manure is stacked in fields, it should be appropriately spread as soon as conditions permit.

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Glossary

Concrete stave storage - A type of liquid-tight animal manure storage structure. Located on a concrete foundation, it consists of concrete panels bound together with cable or bolts and sealed between panels.

Earthen basin or pit - Clay-lined manure or wastewater storage facility constructed according to specific engineering standards. Not simply an excavation.

Engineering standards - Design and construction standards available at Natural Resources Conservation Service (NRCS) or Virginia Cooperative Extension offices. These standards may come from NRCS technical guides, state regulations, or land grant university engineering handbooks or publications.

Filter strip - A gently sloping grass plot used to filter and settle solids from runoff from the livestock yards and some types of solid manure storage systems. Influent waste is distributed uniformly across the high end of the strip and allowed to flow down the slope. Nutrients and suspended material remaining in the runoff water are filtered through the grass, absorbed by the soil and ultimately taken up by plants. Filter strips must be designed and sized to match the characteristics of the livestock yard or storage system, and the expected quantity of runoff.

Glass-lined steel storage - A type of liquid-tight, above-ground animal manure storage structure. Located on a concrete foundation, it consists of steel panels bolted together and coated inside and outside with glass to provide corrosion protection.

Poured concrete storage - A type of liquid-tight animal manure storage structure. Located on a concrete foundation, it consists of poured concrete reinforced with steel.

Contacts and References

For additional information consult the VirginiaFarm*A*Syst Resource Directory. Contact your local Virginia Cooperative Extension agent, Natural Resources Conservation Service office, or the Virginia Department of Conservation and Recreation for information about local ordinances, state regulations, cost-sharing funds, and nutrient management programs.

Acknowledgements.

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 Worksheet 9 "Livestock Manure Storage and Treatment Facilities."

View a list of the Virginia Farmstead Assessment System publications.

 

Reviewed by Bobby Grisso, Extension Specialist, Biological Systems Engineering


Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.

Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.

Publication Date

May 1, 2009