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0 Chapter 4-Site-Speeil /ndustria/ Storm Water 8 Ps <br />• <br />Surface Roughening l <br />What Is It <br />Surface roughening is a temporary erosion control practice. The soil surface is roughened by the <br />creation of horizontal grooves, depressions, or steps that run parallel to the contour of the land. <br />Slopes that are not fine-graded and that are left in a roughened condition can also control erosion. <br />Surface roughening reduces the speed of runoff, increases infiltration, and traps sediment. Surface <br />roughening also helps establish vegetative cover by reducing runoff velocity and giving seed an <br />opportunity to take hold and grow. <br />Heavy Equipment can be used to <br />mechanically scarify slopes <br />Undisturbed Vegetation <br />Undisturbed Area - <br />4s_ ? <br />Tread grooves of <br />track perpendicular <br />to slope direction <br />?,{ Diversion <br />o .? <br />Dozer treads create <br />grooves perpendicular <br />to slope direction '=l <br />- ?. <br />Unvegetated slopes should be temporarily <br />scarified to minimize runoff velocities <br />FIGURE 4.29 SURFACE ROUGHENING <br />(Modified from Washington State, 1992) <br />4 -O 5