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7. The pond does not have a dam or embankment; it is incised (excavated) in the ground. <br />Using the rational method of calculating runoff (as in SEDCAD), the inflow into this 6.6 acre- <br />foot pond would be: 1.84 acre-feet fora 10-year storm, 2.81 acre-feet fora 25-year storm, and <br />3.84 acre-feet fora 100-year storm. These storms would not fill the pond. I used a curve <br />number of 90 (equivalent to barren ground) for the calculation (see attached calculation). <br />The Regulations require the permittee to submit an as-built certification fora "sedimentation <br />pond" [Section 4.05.6] or a temporary impoundment that impounds water behind a dam [Section <br />4.05.9 (2), which subjects such an impoundment to Section 4.05.6]. Pond 9-P1 was constructed <br />to treat mine dischazge (presumably, dissolved solids and pH), not to control sediment, and <br />therefore does not meet the definition of a "sedimentation pond" [Section 1.04(115]. Dissolved <br />solids and pH do not fall within the definition of "sediment" [Section 1.04(1 14)]. Consequently, <br />the pond is not subject to the as-built certification requirement of Section 4.05.6. Also, the pond <br />does not impound water behind a dam, and therefore is not subject to the :ts-bui]t certification <br />requirement of Section 4.05.9(2). <br />Given the apparent absence of a regulatory basis for requiring the permitt<;e to submit an as-built <br />certification for the pond, and recognizing the large capacity of the pond compared to expected <br />runoff volumes, I conclude that an as-built certification is not required; the°refgre, the Division <br />should withdraw Item 44. Also, it seems that the Division's right to enforce the as-built <br />certification regulation would have expired upon expiration of any statute of limitation that is <br />applicable in C.R.S. 13-80-101 et seq. <br />