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require extraordinary evidence". The fact that the precipitation amount was based on information provided by a nearby resident (rather than collected on-site by the permittee), and that the storm duration was based on third party estimates rather than on-site storm duration recording, casts some question on the data. Further, we question the accuracy of SEDCAD modeling for a storm duration of 1.5 hours, as included in Jim Stover's submittal, which indicated a peak flow in excess of the design event peak flow for the RSRDA Diversion Segment "B". Short duration storm models are inherently less accurate than longer duration models. The Type II storm model used in the approved permit design delivers 1.1" of rain in approximately 30 minutes on an already wetted surface, so a short duration, high intensity component is built in. Without well documented, site collected data for precipitation amount, storm intensity and duration, the Division relies on the 100 year, 24-hour (Type II) storm event modeling, as included in the approved permit. At the Roadside Portals Mine, the precipitation amount for this design event is 2.2". Unless detailed, site specific documentation is provided to demonstrate higher peak flows, drainage structures are required to function without failure for rainfall events that deliver 2.2" or less within a 24 hour period. Please contact me if you have any questions regarding the enclosed Notice of Violation. Please take note of the specified abatement measures and timeframes. On a related matter, I am aware that maintenance work is on-going at Roadside, to complete necessary maintenance associated with the July 20`h storm event at the site and the August 1 flooding down Coal Creek. If there are any sediment control system breaches still remaining from the July 20 storm event (examples would be the North Portal berm separating Pond 13 drainage from SAE drainage, SAE silt fence breaches at the North Portal and the 016 discharge drill pad, etc.), please ensure that they (and any other such breaches) are repaired/replaced promptly, no later than August 18. The blocked Haul Road 4 culvert at the end of the North Portal West Upper Diversion, and the ditch below the culvert down to Coal Creek is also a high priority item, and should be promptly repaired. I would request that other maintenance and repair work addressed in my inspection reports of August 7 (for problems caused by the July 20 storm) and August 9 (for problems caused by the August 1 flooding of Coal Creek), be completed by August 31, 2006. Please contact me if you foresee any problems with meeting these deadlines. Environmental Protection-Speciali enclosure C: Denver File (w/enclosure)