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4. The Division can not propose a decision for TR-37 until BRL has secured the proper amendment to its NPDES permit for Pond F Please submit a copy of the amended NPDES permit when available. The Division has no further concerns. The appropriate approved amendment to the NPDES permit was placed into the Bowie No. 2 Mine permit application through Minor Revision No. 59. 5. As mentioned in a previous discussion with BRL, the Division does not have jurisdiction over the metal flume that will move discharge water from the Pond F emergency spillway over the Fire Mountain Canal. Therefore, the installation of the metal flume is independent of TR-37. No response was required by BRL. At the request of the Bureau of Reclamation, however, BRL submitted hydrology design pages App-B-7 and App-B-8 and new drawings on Figures 3 and 4 for the channel structures that will take pond F emergency discharge flow over the Fire Mountain Canal. The Division has determined that its jurisdiction ends with the emergency spillway at the base of the pond F embankment and does not include the remaining channel structures. As of the date of this letter, the Division has not received a reply from the Bureau of Reclamation (BOR) concerning BRL's June 20, 2005 responses to the BOR adequacy review letter dated March 17, 2005. However, the Division would like to reply to one of BRL's responses in that June 20, 2005 letter. 6. /n item number one of BRL's adequacy response letter dated June 20, 2005, BRL stated that the calculated capacity of the pump that dewaters pond F was reduced from 397 gpm down to 275 gpm. As shown on page App-B-8 of BRL's June 9, 2005 adequacy response, this reduction in the pump capacity increases the dewatering time for pond F to 2.9 days. The Division has two comments: A. Although not a specific requirement of the Division's regulations, the Division has adopted a guideline that sedimentation ponds need to be dewatered within 36 hours of a precipitation event so that enough pond capacity is available to store the runofffrom a /0 year-24 hour precipitation event. Please install a pump with the capacity to dewater pond F within 36 hours. B. On page App-B-8 of the submittal dated June 9, 2005, BRL has calculated the time needed to dewater the entire volume of pond F that has been set aside for water storage. However, as a worse case scenario, only the time needed to dewater the water volume resulting from the 10 year-24 hour precipitation event needs to be calculated. In order to avoid any confusion, please revise page App- B-8 to reflect this change. 2