2020-09-23_ENFORCEMENT - M2019002

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PERMIT#: M-2019-002 INSPECTOR'S INITIALS: ERR INSPECTION DATE: September 4,2020 The overtopping caused a head cut erosional feature in the outside face of the embankment, approximately 10 feet by 10 feet and 5 feet deep. It appears the Operator placed material in the head cut to prevent further discharge.The Operator stated that the following morning(Thursday, September 3')a second overtopping occurred, approximately 100 feet north of the first event. This created an additional head cut in the outside face of the embankment, approximately 10 feet by 15 feet and 4 feet deep. To stop the overtopping and potential failure of the embankment, the Operator rerouted the pump used to pump decanted water to the cleaned water pond, and discharged water north of the northern permit boundary directly into the unnamed drainage. The Division has identified this as the Pump Discharge Point on the attached Inspection Report Map. The pump and associated hoses had been moved by the time the Division inspected the site. To prevent further overtopping, the Operator also created a new forebay well within the mud retaining area where future mud and process water could be contained without reaching the embankment. Upon review of the permit file after the inspection,and confirmation from the Colorado Department of Health and Environment, the site has a storm water discharge permit, however this permit does not allow the discharge of process waters. The Division walked the unnamed drainage from the southeast permit boundary corner to CR R. The Division observed significant fines from the drainage adjacent the first overtopping downstream approximately 1,100 feet. The Division has identified this area as the Off-site Discharge Disturbance on the attached Inspection Report Map. This area was determined from collected GPS data and site observations and is estimated to be 0.34 acres in size. When discussing the fines and sediment within this area,the Operator stated they wanted to repair and reclaim the damage to the drainage by excavating and hauling the fines back to the mining area, likely using a skid steer. The Division also observed evidence of light brown colored staining on vegetation just before the culvert under CR R. This observation indicates the discharge traveled at least 2,600 feet down the unnamed drainage toward the South Fork of the Republican River,which is 330 feet north of CR R. Based on the evidence observed,the majority of fines dropped out within the first 1,100 feet of the unnamed drainage and discolored water likely reached the South Fork of the Republican River. This has been cited as a possible violation requiring a hearing before the Mined Land Reclamation Board. After inspecting the discharge area, the Division inspected the permit boundary markers. While inspecting the southeast permit boundary, the Division observed topsoil and overburden and been piled across the southern and eastern delineated permit boundaries.The Division used a Trimble Juno 3B to acquire GPS data of the permit boundary markers and the entire disturbance footprint. Upon review of the permit file after the inspection,and based on the collected GPS data,the Division determined the permit boundary markers are likely not in the correct locations,however,the Operator has still affected approximately 1.51 acres of land outside of the approved northern, western, and southern permit boundaries. The Division has identified this area as the Off-site Mining Disturbance on the attached Inspection Report Map. The majority of the off-site disturbance falls between the permit boundary and CR 6 where there is a permitted 50-foot offset from the road. This has been cited as a possible violation requiring a hearing before the Mined Land Reclamation Board. Immediately following the inspection, the Operator formally committed to ceasing mining and processing operations until the sediment storage embankment had been repaired, the embankment reinforced and increased in height by at least I foot, and moving forward,the Operator committed to utilizing the newly excavated forebay for the remaining processing needed to complete the sand requirements of the Interstate 70 reconstruction project. The Operator committed to providing the Division with photographic evidence of the repairs. On Tuesday, September 8,2020, the Operator provided the Division with the repair work photos. The Division accepted the repair work and allowed the Operator to finish mining and processing at the site with the understanding that all waste from the processing plant needed to be contained in the forebay and under no circumstance was the Operator permitted to discharge any further sediment laden waters outside of the permit area. This concludes the Division's Inspection Report; a subset of photographs taken during the time of the inspection are included below. If you need additional information or have any questions, please contact me at Division of Reclamation, Mining and Safety, 1313 Sherman Street, Room 215, Denver, CO 80203, by telephone at 303-866-3567 x8132,or by email at clhott cu sscfi a st ate.co its. Page 3 of 14