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appear to be cost effective at this time. <br /> 8) Three acres beyond that which was estimated to be revegetated <br /> were seeded. <br /> MINE 4 <br /> 1) In order to ensure that voids would not result, the mine entries <br /> were filled with earthen materials, rather than with concrete <br /> rubble, to the block walls. <br /> 2) The corrugated metal protecting the entries was left in place in <br /> order to provide additional protection for the block walls. <br /> 3) Surface containment furrows were constructed in a 'V' shape, <br /> rather than as a trapezoid, in order to simplify the construction <br /> process. <br /> 4) The amount of hay to be incorporated into the bench prior to <br /> seeding was reduced from 5 tons per acre to 2 tons or less due to <br /> the shallow depth of dirt, which was underlain by sandstone. It <br /> did not appear that the depth of dirt was sufficient to incorporate <br /> five tons of hay per acre. <br /> 5) The requirement to scarify the mine bench outslopes was <br /> eliminated because this process would potentially remove a large <br /> amount of the rock which protrudes from the outslope. These rocks <br /> allow the development of less steep shelves immediately uphill, <br /> which provide a good site for plant development. <br /> 6) The presence of a thick and very competent sandstone immediately <br /> below the mine bench prohibited creation of containment furrows. <br /> Containment berms were constructed instead. <br /> 7) As an experiment, a sheeps foot roller was utilized to crimp <br /> straw on a portion of the bench backfill. This method of crimping <br /> was partially successful in holding straw in place, however the <br /> additional compaction of the soil was deemed to be counter <br /> productive, so the practice was discontinued. <br /> 8) Slopes steeper than 3H:1V were to be hydro mulched and hydro <br /> seeded because the large degree of rock would prohibit effective <br /> hand crimping of the mulch. Also, the severity of the slopes make <br /> foot access very difficult, which renders the uniform distribution <br /> of seed by hand unlikely. <br /> 9) Due to the limited depth of soil materials at the benches, it <br /> was felt that a ripper would have only marginal success in <br /> scarifying these areas. Therefore, a spring tooth harrow was <br /> employed for this process. <br /> 10) Safety berms adjacent to the lower bench area, but outside of <br /> 9 <br />