3214 BROADWAY BROADWAY KINECT APARTMENTS 2021-08-11

• • - CITY OF EVERETT STORMWATER MANAGEMENT MANUAL • • clayey soils (USDA Classification Type "C"and"D" soils),long grades, and high precipitation areas. When PAM is applied first to bare soil and then covered with straw,a reapplication may • not be necessary for several months. • 3. Loss of sediment and PAM may be a basis for penalties per Revised Code of Washington(RCW) • 90.48.080. • 3.2.14 BMP C130: Surface Roughening • Purpose • Surface roughening aids in the establishment of vegetative cover,reduces runoff velocity, increases • infiltration,and provides for sediment trapping through the provision of a rough soil surface. Horizontal • depressions are created by operating a tiller or other suitable equipment on the contour or by leaving • slopes in a roughened condition by not fine grading them. • Conditions for Use • 1. All slopes steeper than 3:1 and greater than 5 vertical feet require surface roughening • 2. Areas with grades steeper than 3:1 should be roughened to a depth of 2 to 4 inches prior to seeding • 3. Areas that will not be stabilized immediately may be roughened to reduce runoff velocity until seeding takes place • 4. Slopes with a stable rock face do not require roughening • 5. Slopes where mowing is planned should not be excessively roughened. • 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 methods include stair-step grading, • grooving, contour furrows,and tracking. See Figure 3.2 for tracking and contour furrows. Factors to be considered in choosing a method are slope steepness,mowing requirements,and whether the slope is • formed by cutting or filling. • 1. Disturbed areas that will not require mowing may be stair-step graded, grooved, or left rough • after filling. • 2. 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 contour or gullies will form on the slope. • 3. Areas that will be mowed(these areas should have slopes less steep than 3:1)may have small • furrows left by disking,harrowing,raking, or seed-planting machinery operated on the contour. • 4. Graded areas with slopes greater than 3:1 but less than 2:1 should be roughened before seeding. • This can be accomplished in a variety of ways, including"track walking,"or driving a crawler tractor up and down the slope, leaving a pattern of cleat imprints parallel to slope contours. • 5. Tracking is done by operating equipment up and down the slope to leave horizontal depressions • in the soil. • Maintenance Standards • 1. Areas that are graded in this manner should be seeded as quickly as possible. • • • Volume 11— Construction Storm water Pollution Prevention 3-25 • •