Guidelines for Establishment and Operation of Cattle Feedlots in ...

Table 11 Characteristics of Sedimentation Systems for Cattle Feedlots
Sedimentation
System
General Description length/width
ratio
Basin Wide and shallow with maximum depth less
than 1 metre.
Sedimentation weir controls discharge into the
storage lagoon
Free draining with shallow slope (approximately
0.1%) to sedimentation weir.
Compacted gravel base to allow mechanical
removal of dried sediments.
Terrace Wide shallow waterway with slope 0.1 - 0.5%.
Sedimentation weir controls discharge into
storage lagoon or next terrace
2 - 3 terraces may be constructed in series
Free draining with slope to sedimentation weir.
Compacted gravel base to allow mechanical
removal of dried sediments.
Pond An excavated hole with depth greater than 1
metre.
* Scaling factor is used in Equation 3
Does not drain completely after rainfall
Solids settle to form a sludge layer which must
be removed at intervals of 1 - 5 years
Pond usually needs to be pumped out to allow
de-sludging
scaling
factor λ ( * )
2 - 3 2.5
8 - 10 1
2 - 3 6
General design and performance requirements of sedimentation systems are that they can
achieve effluent flow velocities of .005 m/s or less which are sufficient to enable the
settlement of at least 50% of entrained solids
accommodate the design storm having
– an average recurrence interval of 20 years
– with a duration equal to the time of concentration of the feedlot controlled drainage
area
– using run-off coefficients of 0.8 for the feedlot pens, roads and other hard standing
areas, and 0.4 for grassed areas within the feedlot controlled drainage area.
prevent any waste from leaching through the system lining. For clay lined sedimentation
systems, the liner must consist of at least two layers of clay placed in uniform horizontal
layers, each of 150 millimetres compacted thickness, and must have a permeability of 10 ­
Guidelines for Establishment and Operation of Cattle Feedlots in South Australia, 2 nd Edition 40