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Page 4 of 6 <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 <br />designs that show that a culvert of a certain diameter can handle the designed peak discharge <br />for the designed precipitation event. Please provide the appropriate Sedcad data sheets for all of <br />the loadout culverts. <br />57. Please add a more detailed description in Section 2.05.3(4)(a)(ii)(C) on permit text 2.05-18 <br />and in the Probable Hydrologic Consequences Section 2.05.6(3)(b)(iii) starting on permit text <br />page 2.05-49 for the process of dewatering the sediment ponds, including how Reed Wash will <br />be protected from erosion and siltation from disposal of the pond water. <br />The Division has no further concerns. On revised permit text pages 2.05-19, 56 and 57 of the <br />April 11, 2011 submittal, BRL added text that further described the pond dewatering method <br />and how pond discharge will not affect Reed Wash.