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1 1 1 1 1 Design and Installation Specifications There are different methods for achieving a roughened soil surface on a slope, and the selection of an appropriate method depends upon the type of slope. Roughening meth- ods include stair -step grading, grooving, contour furrows, and tracking. See Fi ure lk 4.1.5 Surface Roughening by Tracking and Contour Furrows (p.306) for tracking and con- tour furrows. Factors to be considered in choosing a method are slope steepness, mow- ing requirements, and whether the slope is formed by cutting or filling. . Disturbed areas that will not require mowing may be stair -step graded, grooved, or left rough after filling. • Stair -step grading is particularly appropriate in soils containing large amounts of soft rock. Each "step" catches material that sloughs from above, and provides a level site where vegetation can become established. Stairs should be wide enough to work with standard earth moving equipment. Stair steps must be on con- tour or gullies will form on the slope. . Areas that will be mowed (these areas should have slopes less steep than 3H:1 V) may have small furrows left by disking, harrowing, raking, or seed -planting machinery operated on the contour. • Graded areas with slopes steeper than 3H:1 V but less than 2H:1 V should be roughened before seeding. This can be accomplished in a variety of ways, includ- ing "track walking," or driving a crawler tractor u and down the sloe leaving a 9 9� g P p� 9 pattern of cleat imprints parallel to slope contours. . Tracking is done by operating equipment up and down the slope to leave hori- zontal depressions in the soil. Maintenance Standards . Areas that are graded in this manner should be seeded as quickly as possible. . Regular inspections should be made of the area. If rills appear, they should be re- graded and re -seeded immediately. 2014 Stormwater Management Manual for Western Washington Volume 11- Chapter 4 - Page 305