Earthen Manure Storage
Encyclopedia
Earthen manure storages are engineered structures used for the storage of liquid livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...

 manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...

. Generally these structure are designed so that about fifty percent of the structure is below existing grade and fifty percent is above. Certain circumstances such a high water table will require the structure to be built nearly all above grade. Conversely, it may be provident to build a deeper storage to accommodate gravity flow of the manure from a barn that is built at grade. Deeper EMSes still require some form of berming around them to prevent surface run-on.

Designs

Cut and Fill
If the in-situ soils are found to have sufficiently low permeability, generally in the order of 1E-9 m/s or less, a cut and fill style design is usually selected. This involves stripping the topsoil, excavating below grade the desired depth and building up berms in lifts of about 15 cm to the desired height, compacting between lifts. The "cut" area is generally scarified and compacted with a sheepsfoot packer.

Compacted Clay Lined
If in-situ soils are not of the quality needed for a "Cut and Fill" design, the next most desirable construction is that of a Compacted Clay Liner. Clay used for the liner may of lower quality than that found in-situ where a "Cut and Fill" EMS is built. However, it must be able to achieve a similar permeability when compacted to a specified Proctor Density. Clay may also be trucked in from a borrow pit. The liner will be at least 1 metre in thickness and installed in 15 cm lifts, compacting between lifts.

Synthetic Lined
In areas where clay soils are not available or it is un-economic to transport it to the site, a synthetic or "poly" liner may be used. High density poly-ethlyene (HDPE) is a common material used for this purpose. This type of liner is usually constructed from large sheets of HDPE welded together on site. Seams and joints must be tested for tear strength and a visual inspection for holes is done before the job is deemed complete. Synthetic liner are usually a last resort as they are significantly more expensive and can pose an environmental threat more readily if the liner is breached for any reason.

Environmental Impacts

Earthen manure storages are often cited as being environmental hazards by opponents of intensive livestock operations. Such claims generally stem from breaches and spills that have happened with older, poorly managed, EMSes. A properly managed EMS is usually much safer than an above ground concrete or steel manure storage which can suffer from catastrophic failure due to the large head pressure encountered. Below ground concrete storages also often suffer from cracking due to settlement. Earthen storages, provided they are not allowed to completely dry out, remain flexible throughout their lifespan, and do not suffer from cracking. Studies have been done on seepage rates from these storages University of Manitoba Study on EMS Seepage that show they are safe and contaminants of concern do not travel in to local aquifers.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK