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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br /> clayey soils(USDA Classi6cation Type"C"and"D"soils), long grades,and high precipitation , <br /> arcas. When PAM is applicd first to bare soil and then covered with straw,a rcapplication may <br /> not be necessary for several months. • <br /> 3. Loss of sedimeot and PAM may be a buis for penalties per Revised Code of Wzshington(RCW) <br /> 90.46.080. <br /> 3.2.14 BMP C'130: Surface Roughening <br /> Purpose <br /> Sur(ace roughening aids in the establishment of vegetative cover,reduces cunoff velocity., incrcases <br /> infiltration,and provides for sediment trapping through the provision of a rough soil surface. Horizontal <br /> dcpressions are creatcd by operating a tiller or other suicable equipment on the contour or by leaving <br /> slopes in a roughcned condition by not fine grading them. <br /> Conditions/or Use <br /> I. All slopes steeper than 3:1 and greater than 5 venical feet require surface roughening <br /> 2. Areas with grades steeper than 3:1 should be roughened to a depth of 2 to 4 inchcs prior to <br /> seeding <br /> 3. Areas that will not be stabilized immcdiately may bc roughcned to rcduce runoCf velocity unbl <br /> seeding takes placc <br /> 4. Slopes with a stable rock face do not requite roughening <br /> 5. Slopes where mowing is planned should not be excessively roughcncd. <br /> Design and Installation Specrflications , <br /> There are different methods for achieving a roughened soil surfacc on a slope,and thc selection o(an <br /> appropriate method depends upon the type of slope. Roughening methods include stair-step grading, <br /> grooving,contour furtows,and tracking. See Figure 3.2 For tracking and contow furrows. Factors to be <br /> considered in choosing a mcthod are slope stcepness,mowing requirements,and whether thc slopc is <br /> fotmed by cutting oc filling. <br /> I. Disturbed:ueas that will not require mowing may be stair-step gradcd, grooved,or IeR rough <br /> after filling. <br /> 2. Stait-step grading is pariicularly appropriate in soils contaiuing large amowts of soft rock. Each <br /> "step"catches material that sloughs from above,and provides a level site where vegetation can <br /> become established. Stairs should be wide enough to work with sundard earth moving <br /> equipment. Stair steps must be on contour or gullies will form on thc slope. <br /> 3. Areas that will bc mowed(thesc areas should have slopes Icss stecp than 3:1)may havc small <br /> fuRows Icft by disking,Uanowing,raking,or sced-planting machinery uperatcd on thc conrour. <br /> 4. Graded areas with slopes greater than 3:l but Icss than 2:1 should be roughcned before seeding. <br /> This can 6c accomplishcd in a variety of ways, including"track walking,"or driving a crawlcr <br /> tractor up and do�w the slope,leaving a panern ofcleat imprims pa�allel to slope cootours. <br /> 5. Tracking is done by operatiog cquipment up aud down the slape to Ica�•e horizontal dcpressions <br /> in thc scil. <br /> Mainfenance Standards <br /> I. Areas that arc graded in this manncr should bc seeded as quickly as possiblc. <br /> Volume 11—Construction Sformwafer Pollution Prevenfion <br /> 3-25 <br />