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• • -3- • <br />transport of this material. The area behind these hales <br />and the outslope of the lower bench will be seeded with <br />an approved seed mixture during late fall of 1992 to <br />increase stability in these areas. <br />2. "That fill has been plar_ed across a drainage for access <br />without a culvert to allow runoff to pass." <br />MCR proposes to create two interceptor ditches, on the <br />west and east sides of the quarry, to prevent runoff in <br />the steep ephemeral drainages from entering the quarry <br />itself. The west ditch, which will be excavated along <br />the existing access road lalternatively the road will be <br />regraded to slope inward to direct ru>>off), will lead <br />from the drainage cited in the inspection report to a <br />natural drainage as indicated on the enclosed map. The <br />east ditch will direct runoff around the east end of the <br />processing and s}lipping stockpile benches and along the <br />main access road to the point shown on the map, where it <br />will empty into a natural drainage that leads to the main <br />drainage channel. According to the quarry superintendent <br />this road is constructed on a thin veneer of fill over <br />solid rock. Thus the installation of a culvert would be <br />expensive, and would cause unnecessary original surface <br />disturbance. MCR proposes to construct a 10-ft wide, b- <br />in. deep riprap dip crossing at the location indicated on <br />the map. The outslope of the access road fill will be <br />ripraped as well (or alternatively the dip-crossing flow <br />will be directed into a pipe) for coursing into the <br />natural drainage below. Our calculations (attached) <br />indicate that this structure would be more than adequate <br />to pass ]0-year 24-hour storm drainage. <br />The ditches will be sized t.o accommodate 10-yr 24-hr <br />storm events in accordance with standard engineering <br />practices. These calculations are not yet complete. <br />3. "That no signs and markers had been erected." <br />Appropriate signs and markers have been erected. <br />Please consider this letter as fulfillment of the <br />requirements on page 3 of the inspection report, <br />"Problems/Possible Violations and Corrective Actions," to <br />erect signs and markers (item 3) and submit plans for <br />corrective action (items 1 and 2) by April 15, 1992. Final <br />