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1 <br />1 <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 hydromulch 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 C130: Surface Roughening <br />9 9 <br />Purpose <br />Surface roughening aids in the establishment of vegetative cover, reduces runoff velo- <br />city, increases infiltration, and provides for sediment trapping through the provision of a <br />rough soil surface. Horizontal depressions are created b operating a tiller or other suit- <br />9 P Y P g <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 maybe 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. <br />I <br />2014 Stormwater Management Manual for Westem Washington <br />Volume Il - Chapter 4 - Page 304 <br />