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embankment compaction. In general, control measltres should not be constructed in existing • watercourses. If at all possible, erosion and siltation control should be accomplished before runoff reaches the main watercotrse. Major siltation control features which aze being included in many highway designs aze sedimentation pools, stilling basins and sediment dams. Figures A-1, A-2 and A-3 (pages A-11, A-12, and A-13, respectively). Large sedimentation pools should be considered during the design stages and incorporated into the construction plans. They may be added to a project during construction but must be subjected to a formal design procedure based on site conditions. These pools should be located at ponds and lakes. This type of sedimentation pool can be permanent, to remain in place after project completion. These pools should be constructed eaziy in grading operations and all runoff from the contributing construction azea controlled to enter the pool before reaching a stream or adjacent watercourse. Periodic cleaning is necessary in order to maintain their effectiveness. There are also many locations on a highway construction project where stilling basins or sediment dams can be constructed as a temporary measure. Figure A-2 and A-3 illustrate structures that can be used to effectively control pollution until permanent controls aze installed. • Special care must be exercised in building and maintaining all sediment dams and basins. If these impoundments pond much water, a failure could result in extensive damage. Temporary berms serve as an effective measure in controlling runoff and preventing erosion Figure A-4 (page A-14) shows the use of temporary berms along the top of a fill slope. The berms should be large enough to control heavy runoff and prevent washout The earth berms shown in Figure A-4 are approximately two feet wide by one foot high and shoulo be compacted by the wheel or track of construction equipment Earth berms can easily be constructed at the end of each day's embankment operations to provide positive erosion control during construction stages. Another type of temporary berm which has been used successfully is a long burlap sleeve filled with sand. This type is effective when installed on essentially completed embankments. The sand filled burlap sleeve remains in place to allow grass to become established before the burlap rots and the sand disperses. Temporary berms can also be placed along the top of cut slopes where runoff might cause erosion along the cut face. A-5