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Regarding water quality issues, staff has determined that the application demonstrates compliance with the performance standards of C.R.S. 34-32.5-116(4)(c), which requires the application to demonstrate that all mined material disposed of within the affected area and all affected areas to be reclaimed as part of the approved application will not result in any unauthorized release of pollutants to the surface drainage system; and C.R.S. 34-32.5- 116(4)(d), which prohibits unauthorized release of pollutants to groundwater from any materials mined, handled, or disposed of within the permit area; and C.R.S. 34-32.5- 116(4)(h), which states that disturbances to the prevailing hydrologic balance of the affected land and of the surrounding area and to the quality and quantity of water in surface and groundwater systems, both during and after the mining operation and during reclamation, shall be minimized. The applicant has secured the appropriate discharge permit from the Colorado Department of Public Health and Environment, Water Quality Control Division, for stormwater runoff and pit dewatering. Staff has determined that the mining methods, being standard for this type operation, are unlikely to cause ambient receiving stream water quality conditions to degrade sufficiently to violate applicable stream standards as a result of mining or reclamation operations. Regarding general floodplain issues, please note that the Act and Rules do not exclude mining activities from floodplain areas, except to the extent that such areas are located on lands covered under C.R.S. 34-32.5-115(4)(f). The exclusions of C.R,S. 34-32.5-115(4){f) do not apply to the Line Camp Pit application. High quality sand and gravel deposits are located in and adjacent to 100-year floodplains throughout Colorado. Literally thousands of gravel pits have been developed in and adjacent to floodplains in the State. The DMG has published a guidance document describing potential impacts and possible mitigating measures for in-stream and floodplain mining.' The Urban Drainage and Flood Control District has likewise published a guidance document for floodplain mining along the South Platte River and its tributaries north of Denver, which is the area of the most extensive floodplain mining in the State.2 DMG routinely reviews and analyzes floodplain mining proposals and requires mitigating measures as needed; this routine procedure was followed in the case of the Line Camp Gravel Pit application. Regarding flood danger issues, staff has determined that the application demonstrates compliance with the performance standards of C.R.S. 34-32.5-116(4)(1), which requires that areas outside of the affected land be protected from slides or damage occurring during the mining operation and reclamation; and C.R.S. 34-32.5-116(4)Q), which requires that all surface areas of the affected land, including spoil piles, shall be stabilized and protected so as to effectively control erosion; and C.R.S. 34-32.5-116(4){h), which states that disturbances to the prevailing hydrologic balance of the affected land and of the surrounding area and to the quality and quantity of water in surface and groundwater systems, both during and after the mining operation and during reclamation, shall be minimized. Staff has determined that the mining and reclamation of the Line Camp Pit will not increase hazards or cause off site damage during flooding of magnitudes up to and including the one percent annual chance (100-year) flood event. ~ "In-Stream Aggregate Extraction and Reclamation Guidance Document." Colorado Division of Minerals and Geology, August 1998. Z `"Technical Review Guidelines for Gravel Mining Activities Within or Adjacent [0 100-year Floodplains." Urban Drainage and Flood Control District, December 1987.