Att 3_CMP - Final

                •     Grassed drains channels, and swales should not be erodible. If erosion is
                      probable, other protective measures such as rock-lining, rock mattresses,
                      reinforced grass channels, and/or geosynthetic lined channels may be
                      utilised.
                •     Rock mattress will be utilised to reduce erosion velocities in drainage lines.
                •     Level spreaders may be used at the outlet of drainage lines to prevent
                      erosion of channel/drain outlets.
                •     Under-road culverts may be provided to prevent vehicles driving through
                      drainage lines and creating turbid water.
                •     Diversion banks will be, when possible, constructed by pushing soil from the
                      lower side of the slope. This results in flatter, more stable structures, by
                      preventing disturbance of the natural surface at the base of the drain, and
                      creating a bund consisting of natural surface soils, which are more likely to
                      revegetate.
                •     Where this measure is not practical due to space, erodible granular soil, or
                      other constraints, cut drains may be used.
                •     Grader or dozer cut V drains will be used only for minor catchments where
                      erosive velocities can be kept low.
                •     More significant diversion channels will involve a flatter cross-section and/or
                      temporary lining.
                •     Control measures will be removed when on-site erosion is controlled and
                      significant permanent vegetation coverage is obtained over all upstream-
                      disturbed land.




                         Figure 1: Temporary Waterway/Drainage Line Diversion




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