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r~uz. rua~,e>. snvnGe <br />Page 2 <br />January 7, 1981 <br />3) The diesel storage area no longer serves this function and <br />has not been in use since aPeroximatel.y September of 1980. Also, a <br />berm surrounding the diesel storage area is in place which serves <br />both to confine water w}lich falls into the area and divert water away <br />from the area. Therefore, it appears adequate sediment control of <br />this area exists at the present time. An inspection of the area will <br />confirm this statement. <br />4) Bob Liddle's comments from a memo of December 8, 1980. <br />1. The twv ditches in question }lave teen redesigned <br />after each of the drainage areas were extended to take intro <br />account the extension areas at true end of thn ditches. [}owever, <br />the areas were replanimetered and the drainage areas of each <br />are smaller than put forth in the amendrtient. They are: <br />ditch 22-D4 - 25.05 acres; ditch 22-D6 - 73.7 acres. There- <br />fom , both of these ditches will have been designed in a very <br />conservative fashion. <br />Pechecked LY~siyn <br />Ditch: 22-D4 <br />Ascription: Diversion above pit <br />Area Drained: 25 acres <br />Grade: 4 percent <br />Peak Discharge: (32(1.19)(1.22) = 46 cfs <br />Ditch: 22-D6 <br />Ascription: Diversion above pit <br />Area Drained: 99 - 100 acres <br />Grade: 7 percent <br />Peak Discharge: 138 cfs <br />l.s can be neon, the peak discharge used in the original <br />design are much greater than for the recalculated ones, therefore <br />no change in design is put forth by TBM for these twu ditches. <br />2. Sandstone riprap caill be placed at the terminus of <br />ditch 22-D6 to reduce the outgoing velocity. The rock will be <br />obtained from the sandstone unit encountered during mining and <br />will be approximately 2-4" in diameter. <br />' 3. Tie clay strata present at the mine will be used to <br />create a liner unde~eath the rock lined outlet of Ditch 22-D4. <br />The material will he hauled to the site, dumped and graded over <br />the hillside. A dozer will be used to spread and grade the <br />material and provide the crompaction necessary to "seal" the material. <br />