2018-03-09_ENFORCEMENT - M2004031

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' E 1 BTT:W004-031 INSPECTOR'S INITIALS: JLE ' INSPECTION DATE:November 8,2017 Operator implemented the Permanent Plan on November 23, 2016. The Operator's Permanent Plan approved ' with AM01 included the design of a gravity fed groundwater drain that will be referred to here as the Orr Drain and reservoir outlet pipes. The final AM01 design for the Orr Drain and reservoir outlet pipes were included in a MEMO from Tetra Tech to the Operator dated August 24, 2016. The purpose of the drain was to ' mitigate elevated groundwater conditions on the Orr property resulting from the installation of the slurry wall surrounding the Hazeltine Mine pit. The Orr Drain allows groundwater to flow into the Hazeltine Mine pit as controlled by the Operator. The location of the Orr drain is near the location of the surface water channel known as the Bull Seep. The Bull Seep was relocated by the Operator to facilitate the mining operations. The Bull Seep now flows on the east side of the Hazeltine Mine between the pit and the Orr property. The Orr drain was not designed to convey all the flows from the Bull Seep into the pit. According to the Operator, the ' Bull Seep conveys water to maintain pre-existing jurisdictional wetlands as well as compensatory wetlands as required by the US Army Corps of Engineers. The design indicated the amount of water necessary to maintain the wetlands and drain the Orr property was not known and that the drain would be operated to regulate the water levels and flows into the mine pit in an effort to accomplish the competing objectives of maintaining the wetlands and draining the Orr property. We first observed the Orr property with Steve O'Brian. At the time of the inspection, the Fulton Ditch was discharging through the turnout into the Bull Seep. Wetland vegetation is well established throughout the Orr property and standing water was observed throughout the property. A larger pond areas has developed on ' the northwest side of the Orr property. During the inspection, Mr. O'Brian took groundwater level measurements at three wells installed on the Orr property. They are designated as MW01, 02 and 03. The ' water elevations of these wells were found to be 5039.34 feet in MW01, 5040.18 feet in MW02 and 5040.27 feet in MW03. Steve O'Brian sent the Division the monitoring results of these wells taken from January 25, 2017 through November 8, 2017. These results are enclosed with this report. Overall, it appears the majority of the Orr property is flooded from both surface and groundwater sources. After inspecting the Orr property, we observed the Orr Drain with the representatives of Al and their ' consultants. Mr.Tom Hessman with Tetra Tech provided a brief description of the construction of the Orr drain. The drain consists of an 18 inch pipe installed through the slurry wall. The Operator installed a concrete headwall with a large metal pile wall driven into the slurry wall. The headwall included a gate to ' close the drain and stop logs. The discharge pipe discharges into a concrete lined channel that crosses the access road for the reservoir. A parshall flume was installed at the top of the pit slope used to measure discharge into the pit. A concrete and rip-rap lined channel allows the Orr Drain discharge to flow into the pit. Mr. Refer provided the Division with documentation that they initiated construction of the Orr Drain on November 23, 2016 and completed the drain on September 22, 2017. On November 21, 2017, the Operator supplied the Division with as-built certification for the Orr Drain. Based on the as-built, the upstream invert ' elevation of the Orr drain is at 5,036.40 feet about .1 foot lower than the approved design. It appears the Operator has installed the Orr Drain in accordance with the approved plan. At the time of the inspection, the Fulton Ditch was turned out and discharging through the channel on the Orr property into the relocated Bull ' Seep within the Hazeltine Mine site. In accordance with the approved plan submitted with AM01,the Orr Drain gate was closed because the Fulton Ditch was releasing water to the Bull Seep. The Orr Drain was not discharging with the exception of a very small leak from the pipe. Given this, a pond of water was observed behind the headwall of the Orr Drain approximately 5 feet deep. Monitoring Wells HZMW-2, 11a and 11b were observed. A significant amount of wetland vegetation has established around these wells and water was observed above the base of the casings. ' Page 3 of 11