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111 <br /> is typical. Studies conducted by the United States Department of Agriculture ! <br /> (USDA)/ARS demonstrated that soil stabilization was optimized by using very high <br /> molecular weight(12-15 mg/mole), highly anionic (>20% hydrolysis) PAM. <br /> . PAM tackifiers are available and being used in place of guar and alpha plantago. <br /> Typically, PAM tackifiers should be used at a rate of no more than 0.5-1 lb. per <br /> 1000 gallons of water in a hydromuich machine. Some tackifier product instruc- <br /> tions say to use at a rate of 3 —5 lbs.per acre,which can be too much. In addition, <br /> pump problems can occur at higher rates due to increased viscosity. ' <br /> Maintenance Standards <br /> . PAM may be reapplied on actively worked areas after a 48-hour period. ! <br /> . Reapplication is not required unless PAM treated soil is disturbed or unless tur- <br /> bidity levels show the need for an additional application. If PAM treated soil is left ! <br /> undisturbed a reapplication may be necessary after two months. More PAM applic- <br /> ations may be required for steep slopes, silty and clayey soils (USDA Clas- <br /> sification Type "C" and "D" soils), long grades, and high precipitation areas. When <br /> PAM is applied first to bare soil and then covered with straw, a reapplication may <br /> not be necessary for several months. ! <br /> . Loss of sediment and PAM may be a basis for penalties per RCW 90.48.080. <br /> BMP C13 : Surface Roughening ! <br /> Purpose <br /> Surface roughening aids in the establishment of cover,vegetative reduces runoff velo- <br /> g <br /> velo- <br /> city, increases infiltration, and provides for sediment trapping through the provision of a <br /> rough soil surface. Horizontal depressions are created by operating a tiller or other suit- <br /> able equipment on the contour or by leaving slopes in a roughened condition by not fine <br /> grading them. ! <br /> Use this BMP in conjunction with other BMPs such as seeding, mulching, or sodding. <br /> Conditions for Use , <br /> . All slopes steeper than 3H:1 V and greater than 5 vertical feet require surface rough- <br /> ening to a depth of 2 to 4 inches prior to seeding.. ! <br /> . Areas that will not be stabilized immediately may be roughened to reduce runoff <br /> velocity until seeding takes place. ! <br /> . Slopes with a stable rock face do not require roughening. <br /> . Slopes where mowing is planned should not be excessively roughened. I <br /> 2014 Stormwater Management Manual for Western Washington <br /> Volume 11- Chapter 4 -Page 304 ' <br />