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III IIIIIIIIIIIII III` ~ ,o ~~ of ~ •~ 1 ~~ i ~ CONSTRUCTION MAT I~EXT OR EXPLORATION OPERATION Presentation Form GENERAL INFORMATION Inspection Date: July 5, 2001 File No.: M-78-052 Permit Type: Surface, 1 12c Permitted Acres: 629.3 acres Permittee: Mobile Premix Concrete, Inc. Commodity: Sand & Gravel Operator. Mobile Premix Concrete, Inc. County: Adams Existing Bond: $622,650 Adequate?: YES Method of Mining: Dry Mining & Dewatering Specialist: Totn Schreiner NATURE OF VIOLATION(S) (Descrihe rlie nctivity) At least 550 linear feet of the Bull Seep has been relocated within 200 feet of the South Platte River, contrary to what is required by Permit No. M-78-052 for [he Howe Pit. Of these 550 linear feet, approximately 300 linear feet of the Bull Seep were relocated immediately adjacent to or at the toe of the pre-existing flood control levee, and only 60 feet from the edge of the South Platte River. The drainage control plan for the Howe Pit specifies that the Bull Seep be relocated to no closer than 200 feet from the South Platte River. The Bull Seep relocation was untimely as the relocation was completed in 1996 rather than prior to excavation and mining in Stage 4 as specified in the mine plan. It appears that excavation and mining began in the Stage 4 area during 1995. It appears that the operator has failed to install the relocated Bull Seep and associated outlet control spillway in accordance with the designs of the approved mine drainage plan. There is evidence that the existing configuration of the relocated Bull Seep is prone to excessive bank erosion. The operator has been routing stormwater and mine water from dewatering operations through the relocated Bull Seep channel and then discharging directly into the pre-existing Bull Seep Slough where flows would have needed to make a 90 degree turn and without the control of a properly constructed outlet spillway. These practices are significantly different from the approved mine drainage plans incorporated into [he 1990 amendment. A major failure of the flood control levee along the South Platte River in the northwest portion of the permit area occurred on May 5. 2001. There is evidence of significant erosion in the relocated Bull Seep and at the Bull Seep outlet prior to a May 3-5. 2001 storm event. There is also evidence of both on-site as well as offsite erosion as a result of the May 5, 2001 levee failure. SERIOUSNESS Administrative, describe - Onsi[e damage, describe -There are four (4) areas of known onsite damage: Area 1 : 84 linear feet of 6-8' cut, vertical bank of Bull Creek Slough near the northwest comer of the Stage 5 Pit Excavation. Area 2 : At least 60-80 linear fee[ of pre-existing flood control dike [ha[ was breached by the South Platte River and subsequently repaired via emergency response by [he Urban Drainage & Flood Control District.