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r Chapter 4 - Best Management Practices for Erosion and Sediment Control 4. 16 TEMPORARY FILL DIVERSION (ES BMP 1 . 16) Definition .. A channel with a supporting ridge on the lower side cut along the top of an active earth fill . Purpose To divert storm runoff away from the unprotected slope of the fill to a stabilized outlet or sediment trapping facility Conditions Where Practice Applies .. Where the drainage area at the top of an active earth fill slopes toward the exposed slope and where continuous fill operations make the use of a DIVERSION - Section 5. 18 (ES BMP 1 . 18) unfeasible . This temporary structure should remain in place for less than one week. Planning Considerations One important principle of erosion and sediment control is to keep stormwater runoff away from exposed slopes . This is often accomplished by installing a dike, diversion or paved ditch at the top of a slope to carry the runoff away from the slope to a stabilized outlet or downdrain . In general , these measures are installed after the final grade has been reached . On cuts , the measures may be installed at the beginning since the work proceeds from the top, and the measures have little chance of being covered or damaged . On fills , the work proceeds from the bottom to the top and the elevation changes daily. It is therefore not feasible to construct a compacted dike or permanent diversion which may be i covered by the next day's activity. The temporary fill diversion is intended to provide some slope protection on a daily basis until final elevations are reached and a more permanent measure can be constructed . This practice can be constructed by the use of a motor grader or one of the smaller dozers . To shape the diversion , the piece of machinery used may run near the edge of the fill with its blade tilted to form the channel as described in Plate 4 . 16a . This work should be done at the end of the working day and should provide a channel with a berm on the lower side to protect the slope . Wherever possible , the temporary diversion should be sloped to direct water to a stabilized outlet. If the runoff is diverted over the fill itself, the practice may cause more problems than it solves by concentrating water at a single point. 4-59