MCU14/0028 Appendix 3 chicken-meat-guidelines

showed that it is not feasible to define a set of weighting factors covering highly detailed terrain
types, since the relationship between regional wind patterns and local terrain is highly variable and
not able to be classified beyond a fairly basic level.

The factors are shown in Table 4, along with the direction in which each factor should be applied.
The slope referred to is determined by the topographical features of each site.

Table 4 – Values of terrain weighting factor S3


                                                                   Weighting factor
 Terrain
                                                              Downslope                Upslope
 Flat                                                            1.0                   1.0
 Valley drainage zone –                                          1.2                   1.0
 (Broad valley >10 km and/or a valley or gully
 with low side walls, where the average slope
 from centre of valley/gully to confining ridgeline
 is <2%)
 Valley drainage zone –                                           1.5                  1.0
 (Average slope from centre of valley/gully to
 confining ridgeline is 2–5%)
 Valley drainage zone –                                           2.0                  1.0
 (Average slope from centre of valley/gully to
 confining ridgeline is >5%)
 Low relief at >2% from farm site                                 1.2                    -
 (Not in a valley drainage zone, but the source
 lies above the receptor at an average grade of
 more than 2%)
 All other situations                                             1.0                  1.0

Notes:
1.    These factors may not apply where:
       a)    sea-breezes are a significant influence on weather patterns (i.e. in coastal regions)
       b)    odour is emitted from elevated vent sources (If sheds are fitted with elevated vents proceed to Section 2.6
             Plume dispersion modelling).
2.    These terrain weighting factors should be applied:
       a)    by checking the location of the meat chicken farm in relation to the topography
       b)    for the range of distances applicable to meat chicken farm impacts. However, the application of these
             weighting factors is dependent on the homogeneity of terrain between source and sensitive land use. For
             example, if the terrain remains similar between the meat chicken farm and sensitive land use the weighting
             factor can be applied for an indefinite distance. The weighting factor is, however, less reliable if significant
             terrain changes occur between source and sensitive land use.
3.    The use of these terrain weighting factors does not affect the application of surface roughness factors discussed in
       Section 2.3.4.
                                                                   O
4.    Downslope factors should be applied across an angle of 90 centred on the terrain feature. Upslope factors should
                                        O
       be applied across an angle of 60 centred on the terrain feature.




Queensland Guidelines Meat Chicken Farms                                                                           51