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Chapter 4-Site-Specific /ndu&! Storm water BMPs • <br />Straw: Bale!.Barrier <br />What Is It <br />Straw bales can be used as a temporary sediment barrier. They are placed end to end in a shallow <br />excavated trench (with no gaps in between) and staked into place. If properly installed, they can <br />detain sediment and reduce flow velocity from small drainage areas. A straw bale barrier prevents <br />sediment from leaving the site by trapping the sediment in the barrier while allowing the runoff to <br />pass through. It can also be used to decrease the velocity of sheetflow or channel flows of low-to- <br />moderate levels. <br />When and Where to Use It <br />A straw bale barrier should be installed prior to major soil disturbance in the drainage area. This, <br />type of barrier is placed perpendicular to the flow, across the bottom of a slope or minor <br />drainageway where there is sheetflow. It can be used at the perimeter of the work area, although <br />is does not have to surround it completely. It can also be very effective when used in combination <br />with other erosion and sediment control practices. A straw bale barrier may be used where the <br />length of slope behind the barrier is less than 100 feet and where the slope is less than 2:1. <br />I What to Consider <br />The success of a straw bale barrier depends on proper installation. The bales must be firmly staked <br />into the entrenchment and the entrenchment must be properly backfilled. To function effectively, <br />the bales must be placed end to end and there can be no gaps between the bales. <br />Straw bale barriers are useful for approximately 3 months. They must be inspected and repaired <br />immediately after each rainfall or daily if there is prolonged rainfall. Damaged straw bales require <br />M <br />• <br />• <br />4-!O