Laserfiche WebLink
Y~^ <br />Item #3 Colowyo is completing the design work for the East Taylor Pond per Technical <br />Revision 33. Design information will be submitted with that Technical Revision. <br />Item #4 Our proposal does not include any changes to the topography in the vicinity of <br />the West Tributary to Streeter Ditch. Initial analysis of surface runoff flows and <br />velocities (during TR-22) indicated there would be no need for a designed rip rap <br />channel to be located in this watershed. The shape of the watershed was such <br />that a defined drainage channel would not be necessary but, to be conservative, <br />we provided for a rip rap channel anyway. Because SEDCAD is so limited it <br />could not produce a reasonable drainage channel fora 10-year event. Using a <br />100-year, 24-hour precipitation event, we "forced" the SEDCAD model to <br />produce the drainage design found in the permit. <br />Subsequent observations of the watershed, with its gentle, undulating <br />topography, confirm that a defined rip rap channel will, as predicted, be <br />unnecessary. The combination of revegetation and intermittent rock check <br />structures will be adequate to control erosion. <br />For these reasons, the plans for the West Tributary were removed from the <br />permit. <br />Item #5 The upper section of the West Pit Ditch (station 15 to station 35) performs a <br />number of important functions. The ditch 1) aids in controlling runoff from the <br />extensive area to be reclaimed when the West Pit is completed, 21 provides a <br />gentle overall slope to the reclaimed surface. There is always some potential <br />that the final topography of the West Pit will need to be further modified to <br />form a more defined swale. The final configuration of the final pit is dependent <br />on future coal sales and, as such, our present prediction is based on the best <br />information we have available at this time. <br />Item #6 The lower portion of the Gulch B ditch was eliminated and the upper portion of <br />the old Gulch B ditch (station 30 to station 83) has essentially become part of <br />the West Pit Fill ditch (station 75 to station 1251. <br />Item #7 The Final West Pit Ditch profile on the old map 33A (station 0 to station 87) <br />corresponds to the West Pit Ditch found on the old Map 19, Post Mining <br />Topography, and is the subject of Technical Revision Item #2 of the original <br />submittal. <br />Please contact me if you need any additional information. <br />Sincerely, <br />~~ ~'~ <br />ames A. Kiger <br />Sr. Environmental Engineer <br />btb <br />xc: R. G. Atkinson <br />File <br />