It's not a
pleasant statistic: A l00-cow dairy herd can produce as
much waste as 2,400 people. But that's not the only unpleasant fact: In certain types of soil, this waste can
seep through the ground and reach groundwater,
contaminating it with nitrate and bacteria.
In most cases,
animal waste must be stored temporarily before it can be
disposed of or used. The waste can either be stored for a
few days on the feedlot, or it can be stored for several
months or more in waste storage structures.
Storage on the feedlot
If you store animal waste on the feedlot, locate the lot far away and downhill from any wells, sinkholes, or surface water. Make provisions to collect runoff water from the feedlot for proper disposal. Also, remember to remove new waste deposits every few days. Wastes are usually spread as fertilizer.
Waste storage structures
Waste storage
structures allow you the flexibility of determining the
proper time to field-apply manure to use it as
fertilizer. But just as with a feedlot, waste storage
structures should not be located near surface water or
wells. Check local and state requirements before
beginning construction of a structure.
In many cases,
unlined, earthen storage facilities provide livestock
producers with a low-cost alternative to storing wastes
in concrete or metal structures. The three most common
earthen structures are earthen storage basins, anaerobic
treatment lagoons, and runoff holding ponds.
Earthen
storage basins. These are small, short-term
storage ponds that hold concentrated manure until it can
be hauled. They replace the concrete and steel storage
tanks. However, these concentrated wastes can cause odor
problems.
Anaerobic
lagoons. These are manure-treatment facilities,
which must be designed for the amount of manure they
receive. A lagoon is considerably larger than an earthen
storage basin. Also, the manure it holds is not as
concentrated as that in an earthen basin. The manure is
diluted with water and undergoes anaerobic decomposition.
A lagoon must be pumped down once or twice each year, but
it should not be emptied.
Runoff
holding ponds. These are storage ponds that
collect the runoff water coming from an uncovered
feedlot. Before reaching the holding pond, the runoff
water goes through a settling basin where the solids
settle out. The holding pond should be regularly pumped
empty on the land, as long as doing so will not create a
pollution problem.
Divert extraneous
water away from earthen structures. This can be done by
installing gutters on roofs. Terraces around the earthen
structure can surface water, preventing it from entering
the basin, lagoon, or holding pond.
Seepage
With all earthen
structures, the greatest groundwater concern is that
wastes will seep through the bottom of the basin to
groundwater. However, seepage is usually not a problem if
the earthen structure has a clay bottom.
When the bottom of
the structure is something other than clay- sandy soil,
gravelly soil, or fractured rock, for instance-you must
seal it. Sealing can be done with compacted clay, plastic
lining, or any other material that keeps water from
seeping through the ground.
Some states require
that soil borings be made to determine the composition of
the soil and evaluate the risk of seepage. Also, some
states require that the earthen structure design be
approved by a registered engineer or someone with
equivalent credentials.
Vegetative filters
Infiltration areas,
such as vegetative filters, are sometimes used as an
alternative to runoff holding ponds. And like holding
ponds, they must be preceded by a settling basin.
Vegetative filters
channel runoff water from the feedlot, allowing it to be
taken up by the vegetation. Runoff also infiltrates the
soil, but it is believed that vegetative filters do not
pose a groundwater hazard when they have been constructed
properly.
Vegetative filters
cannot handle large amounts of runoff water, so most
states limit their use to small operations. In some
states, "small" means operations with about 300
beef or dairy cattle or 750 hogs. Check with the state
pollution control agency for guidelines because certain
states do not permit the use of vegetative filters at
all.
Solid manure storage
Solid-manure
storage is possible when you add enough bedding until the
manure contains enough solids to be stacked in a pile. To
prevent leaching to groundwater and to make loading
easier, stack manure solids on a concrete pad.
Cover the storage
area with a roof to prevent rain and snow from causing
the manure to run off. This will not only prevent
groundwater contamination but also will preserve the
nutrient value of the manure.
Collect any runoff
from the solid-manure storage area, and apply it to
growing crops.
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