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<br />a depression effect rather than a pond. Sides of the pond will be pushed <br />' in with a bulldozer to create a gradual descent into the depression. <br />Pond 5 is located in a natural drainage and is constructed with the required <br />principal and emergency spillways. This pond is mostly in-situ. No addi- <br />' tional work will be required to abandon Pond 5. <br />3. Using the configuration of Pond 4 shown on the Reclamation Map in relation <br />to the proposed final contours, approximately 30 acres will drain into <br />Pond 4 after mining is complete and the diversion ditches removed. Using <br />' a 100-year, 24-hour storm value of 2.0 inches, and ratio-ing to values <br />.~ given in Table 4, page III-21, the anticipated maximum value will be <br />2.0/1.8x0.7/12x30 = 1.95 acre-feet.~Th'erefore a final pond size of <br />'/! \~4 acre-feet will be sufficient to ensure no runoffs from the pond. <br />-~ \` 1, 11 <br />` ~S~u)Since Pond 5 is located in a natural drainage, it is clear that it will <br />~•~~a',~~ „receive sufficient runoff to meet its use as a stock watering pond. <br />~~ <br />4. Several existing ponds presently collect water that has passed through <br />r ~ spoil. It should be more accurate to collect water samples from these <br />existing ponds and analyze the water than try to predict water quality <br />from a hypothetical situation. The attached table gives analytical <br />results of a water sample collected from Pond 1 on 11/16/83. This <br />analysis does not indicate any adverse impact on its intended use as <br />a stock watering pond. _ <br />Sediment Ponds <br />1 1. Pond 1 will be removed in the near future and will present no long range <br />erosion problems. Pond 2 dimensions average 247'x42'x12' (roughly 2.8 <br />' acre-feet). Pond 3 dimensions average 320'x32'x30' (roughly 7.0 acre-feet). <br />The drainage area above Pond 2 is 25 acres. Water into Pond 3 comes from woa~ <br />27 acres. Using the format and logic presented in Table 4, page III-21, k;.~~ <br />the required sizes for Ponds 2 & 3 are 1.46 and 1.58 acre-feet respectively.'~,~ <br />o_ <br />Obviously, both these ponds are oversized. Therefore, there should be ~"~~"'e <br />no problems associated with erosion after abandonment. <br />~' _2_ <br />