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I <br /> This technique works with standard h dromulch(1,500pounds per acre <br /> q Y <br /> minimum) and BFM/MBFMs (3,000 pounds per acre minimum). <br /> • Areas to be permanently landscaped shall provide a healthy topsoil <br /> that reduces the need for fertilizers, improves overall topsoil quality, <br /> provides for better vegetal health and vitality, improves hydrologic <br /> characteristics, and reduces the need for irrigation. This can be <br /> in er of <br /> Recent <br /> accomplished research has <br /> anumb shown thatways:the best method to improve till soils is <br /> to amend these soils with compost. The optimum mixture is <br /> approximately two parts soil to one part compost. This equates to 4 <br /> inches of compost mixed to a depth of 12 inches in till soils.Increasing <br /> the concentration of compost beyond this level can have negative <br /> effects on vegetal health,while decreasing the concentrations can <br /> reduce the benefits of amended soils.Please note: The compost should <br /> meet specifications for Grade A quality compost in Ecology <br /> Publication 94-038. <br /> Other soils, such as gravel or cobble outwash soils,may require <br /> different approaches. Organics and fines easily migrate through the <br /> loose structure of these soils. Therefore,the importation of at least 6 <br /> inches of quality topsoil,underlain by some type of filter fabric to <br /> prevent the migration of fines,may be more appropriate for these soils. <br /> Areas that already have good topsoil, such as undisturbed areas, do not <br /> require soil amendments. <br /> • Areas that will be seeded only and not landscaped may need compost <br /> or meal-based mulch included in the hydroseed in order to establish <br /> vegetation. Native topsoil should be re-installed on the disturbed soil <br /> surface before application. <br /> • Seed that is installed as a temporary measure may be installed by hand <br /> if it will be covered by straw,mulch, or topsoil. Seed that is installed <br /> as a permanent measure may be installed by hand on small areas <br /> (usually less than 1 acre)that will be covered with mulch,topsoil, or <br /> erosion blankets. The seed mixes listed below include recommended <br /> mixes for both temporary and permanent seeding. These mixes,with <br /> the exception of the wetland mix, shall be applied at a rate of 120 <br /> pounds per acre. This rate can be reduced if soil amendments or slow- <br /> release fertilizers are used. Local suppliers or the local conservation <br /> district should be consulted for their recommendations because the <br /> appropriate mix depends on a variety of factors, including location, <br /> exposure, soil type, slope, and expected foot traffic. Alternative seed <br /> mixes approved by the local authority may be used. <br /> I <br /> 446 Volume II—Construction Stormwater Pollution Prevention February 2005 <br />