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designs are provided in Appendix 13-12.3 of the PAP. Postmine channels are designed to safely convey
<br />the peak discharge from the 10-year, 24-hour storm event in accordance with Rule 4.05.3.
<br />In the North Pit area, a section of Postmine Drainage Channel PM-10, and the entirety of PM-11, PM-
<br />21, PM-21B, PM-9, and PM-13 were included in SL-2. PM-9 and PM-13 drain east to Sediment Pond
<br />11 adjacent to Grassy Creek, while the other channels with the exception of PM-11 drain into Annand
<br />Draw (PM-11 is actually a short segment of Annand Draw drainage that was impacted by road
<br />construction and erosion, and subsequently reconstructed). The drainage segments noted in the North
<br />Pit area, with the exception of PM-11, had been evaluated as a part of the SL-1 bond release, but were
<br />excluded from the Division's SL-1 approval due to erosional stability concerns.
<br />A large number of permanent channels were constructed within the Neck Pit and South Pit areas. The
<br />channels were included in the SL-2 application, and have been evaluated by the Division for erosional
<br />stability and compliance with approved designs, as a part of the SL-2 review.
<br />Neck Pit area drainages PM-22, PM-16, and PM-20 drain into Annand Draw, as do PM-8 and PM-15,
<br />which drain the northern portion of the South Pit Area. All of these drainages were included in the
<br />SL-2 application. Sediment Pond 010 is located on Armand Draw, downstream of all pit area
<br />disturbance in the watershed.
<br />The largest watershed in the South Mine Area drains into Pond 012, which discharges to Grassy
<br />Creek. Designated channels in the watershed include PM 1-1, 1-2, 1-3, 6-1, PM-2, 18, 19, PM-7, 7A,
<br />6-2, 6-2A, 5-1, and 54A. All of these channels drain into Pond 012A, constructed upstream of Pond
<br />012 to provide additional sediment control in the watershed. All of the drainages listed, with the
<br />exception of PM-6-2, were included in the SL-2 release request. PM-6-2 extends from the confluence
<br />of PM-6-1 and PM-7 down to Pond 012A, and channel construction has not yet been completed along
<br />the drainage. The lower-most portion of the watershed, including PM-6-3 and adjacent slopes down
<br />to Pond 012, was not included in the SL-2 application, due to a slide area on the slope northeast of
<br />Pond 12. Slide remediation and final reclamation in the Pond 012 vicinity was delayed to allow for
<br />completion of hydrologic and geotechnical investigations and remediation plan development. The
<br />remediation plan was submitted to the Division in February 2010 and is under review.
<br />Two smaller watersheds are located in the southwestern portion of the South Pit area. The southern
<br />of the two drains to Pond 14 and includes PM-3-1, PM-3-1A, PM-3-2, PM-3-2A, and PM-14. The
<br />final watershed drains to Pond 13, and includes PM-4, PM-4-1, PM-3-2,
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