Laserfiche WebLink
4. For the 25year, 24-hour and the 100 year, 24-hour rtorm eventr, the tap ofreda'ment rtorage it rhown to be <br />above the low-hole rpillway elevation (6784.0 feet). Thir it becaure there are conrervative demonrtrationr <br />modeled with the primzpal rpillway clogged Ta clarify thirpleare either footnote the cover page to each model <br />run accardingy, or remove the reference to tap of rediment rtorage fmm the Elevation-Capacz7y-Dircbarge <br />Tabler far both the 25year, 24-hour and 100 year, 24-hour event demonrtratianr. <br />Response: SCC has revised the 25-year and 100-year, 24-hour storm event SEDCAD demonstrations <br />to include a footnote on the SEDCAD demonstration cover page that indicates the estimated top of <br />sediment storage is a conservative elevation. The text on page 13-3A.4 has also been revised to <br />indicate that the 25-year and 100-year storms over estimate sediment storage because the principal <br />spillway is clogged. It is important to note that while the estimated top of sediment storage elevations <br />for the 25-yeaz (6.784.4 ft.) and 100-year (6,785.4 ft.) are above the principal spillway invert elevation <br />(6-inch dewatering orifice - 6,784.0 ft}, the respective sediment storage elevations are less than the top <br />of the 36-inch CMP riser (6,786.8 ft) portion of the principal spillway. <br />In the rupplemental information rabmitted for the ure of turf reinfareed matr, two of the SEDCAD utility <br />runr are incorrectly labeled. On page 13-12.3-180 and 13-123-181 YPM-20 zr titled YPM-B for the 8% <br />and 32% dope derignr. <br />Response: The channel designs have been corrected to show that pages 13-12.3-180 and 13-12.3-181 <br />aze fox Channel I'PM-20. <br />Attached are revised/updated material and insertion instructions. Two copies of this response have <br />been sent to you at the Grand Junction office and a third copy, also addressed to you, has been sent to <br />the Division's Denver office. Should you or aay other member of the Division have questions <br />regarding the information, please contact me at (970) 276-5227. <br />Sincerel <br />i~~~ <br />Roy A. Karo <br />Reclamation Manager <br />Seneca Coal Company <br />enclosure(s) <br />cc <br />John Husband (BLIvT) <br />Cazl Johnston (OSMRE) <br />Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 <br />Telephone (970) 276-3707 • FAX (970) 276-3014 <br />