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Page 4 of 6 <br />49. Please provide a more detailed description in Section 2.05.3(3)(c) on permit text page 2.05-9 <br />and in Section 2.05.6(2)(a)(i) on permit text page 2.05-43 that describes the sediment control <br />and coal spillage control that will be utilized in the construction and operational use of the <br />Reed Wash bridge. <br />The Division has no further concerns. Permit text pages 2.05-9 and 2.05-45 were revised in the <br />April 11, 2011 submittal to include a discussion of the sediment and coal spillage control <br />measures. <br />49A. As required under Rule 4.03.1(4)(e), please provide designs which show that the bridge can <br />safely pass the runoff from a 100 year-24 hour precipitation event. <br />50. Since there are several locations where the railroad spur and loop are close to Reed Wash, the <br />Division suggests that a barrier, such as a berm, be constructed between the railroad tracks <br />and Reed Wash in case of a coal spill from the railcars. <br />As explained in the April 11, 2011 revised permit text sections 2.05.3(4), 2.05.6(2) and <br />2.05.6(3), Exhibit 9 and Map 16, berms and silt fence will be used to contain any coal spills <br />that might occur near Reed Wash. However, examination of Map 16 shows that there is a <br />section of Reed Wash that is about 350 feet northwest of pond 2 that comes to within 60 feet of <br />the railroad loop track but is protected only by ditch D2-b. Please consider adding a section of <br />protective berm on the outside of ditch D2-b in this area and revising Map 16 accordingly. <br />55. Under Rule 2.05.3(4), in the Sedcad designs, CAM is using 1.4 inches, 1.8 inches and 2.2 <br />inches as the design precipitation events for the 10 yr 24 hour event, 25 year 24 hour event and <br />100 year 24 hour event respectively. However, referring to the NOAA Atlas 2 "Precipitation- <br />Frequency Atlas of the Western United States ", the Division obtained values of 1.6 inches, 2.0 <br />inches and 2.6 inches respectively. It appears that CAM may have used the NOAA May to <br />October precipitation event figures rather than the NOAA annual precipitation event figures. <br />Please justify the precipitation event values used in the Sedcad designs or revise the Sedcad <br />designs accordingly. <br />The Division has no further concerns. Sedcad designs in Exhibit 9 using the NOAA annual <br />precipitation event figures were provided in the April 11, 2011 submittal. <br />56. Under Rule 2.05.3(4), in the Sedcad designs for the west culverts, a curve number of zero is <br />used for the irrigated wetlands area, citing a ground cover of 100% as justification for that <br />curve number. If the wetlands are saturated or are comprised of standing water, a precipitation <br />event could produce runoff, in spite of the vegetative cover. Please describe the nature of the <br />wetlands as it relates to the determination of the curve number. <br />In the submittal dated April 11, 2011, CAM revised the curve number of the wetlands to 74, <br />which is a reasonable value to the Division. However, the April 11, 2011 submittal left out the <br />Sedcad peak discharge data sheet for the west culverts that had been included in the original <br />submittal on page Exh-9-7. In addition, there are no Sedcad data sheets that show the peak <br />discharge for the designed event for the other culverts on site. Finally, there are no Sedcad