Laserfiche WebLink
• <br />Y <br />~~ r~ <br />~~ ~~ <br />w <br />w ~~ <br />TUTTLE APPLEGATE RINDAHL, INC. <br />Consultants for Land and Resource Development <br />Mr. Eli 11 Dei3root, P. E. <br />Urban Drainage and Flood Control District <br />June 16, 1968 <br />Pape E <br />Enclosed are copies of the two cross section drawings used <br />to make the calculations. Table 1 is a summary oT the <br />channel area ealculatlons that were mnde. <br />TABLE 1 <br />COAL CREEK STORAGE CALCULATIONS <br />Historic Conditions Developed Conditions <br />t3ection iN dth Area <stl Flidth Area (s T) <br />A-A STD 1660 500 4400 <br />B-B TE0 2300 430 1976 <br />C-C 390 1730 260 3170 <br />D-D 740 2193 300 4000 <br />E-E 700 2130 320 E3S0 <br />Please note tfiat in our discussions about a channel width of <br />80 teat, Me have proposed that this is a minimum width that <br />would be left. As you can see in the table above, Mc will <br />be leaving a wide flootlpiain after reclamation in numerous <br />instances. I would stress that we are not putting more <br />property into the flootlpiain even though storage is <br />increased. Since we are dropping the channel invert, there <br />will be no more inundation than would be experienced during <br />pre-mining condit2ons. <br />2. Enclosed is a tabulation sheet for stream gaping records !n <br />Lhs area that were used to estimate basin runoff. Sediment <br />yield calculations are supplied at the bottom antl are based <br />on annual flow for She basin. A total of E67 cubic yards <br />per year is calculated using tfiis method which is equivalent <br />Lo approximately 290 tone per year. This volume of sediment <br />would fit in 12 dump trucks. Therefore, I propose that Coal <br />Creek is not a significant contributor to the sediment <br />transport issue for the South Platte River. This mining <br />pro~sct will not significantly impact the sediment load on <br />the stream system. In addition, this stream is ephemeral. <br />Therefore, this turtfiar reduces it^ importance to the <br />sediment issue. <br />