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_l1- <br />The Purgatoire River is a perennial stream. Very little information was given <br />in the application about the Ciruela Canyon, Santistevan Canyon, Apache Canyon <br />and Wet Canyon drainages, but it appears that all contain either intermittent <br />or ephemeral streams. Monitoring is required under Stipulation No. 12 to <br />obtain further baseline information. <br />Water quality in the Purgatoire River and Ciruela Canyon may be affected by <br />mine discharge water. The Purgatoire River is a perennial stream that flows <br />north of the surface disturbance. The Ciruela Canyon drainage is an ephemeral <br />or intermittent tributary of the Purgatoire River that flows primarily in <br />response to snowmelt or rainfall. It receives mine water discharge from a <br />settling pond. Water that is collected underground is pumped immediately to <br />the surface and held in a settling pond. This pond discharges through a <br />dewatering device into the Ciruela Canyon drainage. The discharge is <br />monitored regularly in accordance with the applicant's NPDES permit. <br />The applicant has submitted a discussion on the affect of mirie water discharge <br />in the Purgatoire River during a low flow and a mean flow. Table 7 on page 40 <br />of Exhibit 6 of the permit application, gives a description of the change in <br />concentration for 14 parameters. <br />The Ciruela Canyon Drainage has been diverted to make room for expansion of <br />the coal refuse pile. The applicant states that this diversion will be <br />permanent. The Division has reviewed the designs and has found that the <br />diversion meets all applicable requirements for a permanent structure. <br />The sediment control system has been reviewed by the Division. Designs for <br />the sediment control system are found on pages 2.05-12 through 2.05-18 of <br />Volume 1 and in Exhibit 6 of Volume II of the permit application. <br />Surface runoff from the disturbed area is contained by two sediment ponds. <br />These ponds are capable of containing the runoff generated by a 10-year, <br />24-hour storm event and are designed to contain 0.1 acre-feet of sediment per <br />acre of disturbed area. The ponds are both equipped with principal spillways <br />and emergency spillways capable of passing the peak flow from a 25-year, <br />24-hour storm event. The principal spillways are gated, but the gate will be <br />opened a calculated amount to allow for automatic dewatering with a detention <br />time of 24-hours. A series of ditches route disturbed drainage water to the <br />ponds and undisturbed drainage around the disturbed area. These ditches are <br />capable of handling the peak flow from a 10-year, 24-hour storm event. <br />No water quality information is available on the discharge from these ponds <br />since they have only discharged once. The applicant states that the storm <br />that caused the ponds to discharge was believed to be in excess of a 10-year, <br />24-hour storm. It is anticipated that no significant impacts on surface water <br />quality will result from surface runoff. <br />The application does not contain a statement, certified by a registered <br />professional engineer, that the sediment ponds have been constructed as <br />designed, therefore, the following stipulation is necessary in order to comply <br />with Rule 4.05.6(7): <br />