2000-12-01_REVISION - M1977342 - Laserfiche WebLink

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MINE ID # OR PROSPECTING ID#: M-1977-342 PAGE: 4 INSPECTION DATE: 11-14-00 INSPECTOR'S INITIALS: ACS until 2001, the contractor will not have to deal with frozen soil and subgrade, snow, and poor working conditions. Abetter work product will result by deferring completion of the backfilling. The installation of the dual HDPE pipelines, the continued readiness of the 3-Dam pump station, and the large amount of storage capacity in the south pond even with the notch in the dike results in an adequately prepared Environmental Protection Facility for the next 5 or 6 months. In fact, containment is better assured at this point than it was prior to the installation of the pipelines. • The complete set of drawings for the 3-Dam seep water pipeline project were reviewed during this inspection. It was determined that the drawings would be useful to the Division in regulating the new and modified Environmental Protection Facilities involved. Henderson should forward a set of the drawings to the Division at the earliest opportunity for inclusion in the technical revision TR-09 file. • Prior to putting the new pipelines into service, the required integrity testing must be completed and the results of the testing must be accepted in writing by the Division. The Division further requires a pipeline construction report and engineers certification in accordance with Rule 7.3.2(2) of the Hard Rock/Metal Mining Regulations (see Stipulation No. 1 to the approval of technical revision TR-09). • The Division requires an affirmative statement that both pumps are installed and in working order at the 3-Dam pump house. This pump house should not be decommissioned until all of the new Environmental Protection Facilities approved in TR-09 are installed and the Division has accepted the certifications. • The north and south collection dikes are apparently monofill earthen impoundments. It was observed during this inspection that numerous mature trees are growing in the dikes. The presence of deep-rooted trees and the lack of zoning in the dam fill make these dikes unsuitable for long term storage of water. The dams can only serve the purpose of collection ponds for routing of water to the pipelines or pump station and for emergency temporary storage of water. The ongoing logging operations at the Henderson Mill site were observed. Henderson has recently completed a pine beetle survey on their property and determined that there is a burgeoning infestation located near the left abutment of No. 1-Dam. The rest of the mill property is free of beetles. It is believed that the beetles migrated onto the Henderson property from public land located to the east, where there is an obvious beetle problem. Henderson has recently timbered the trees identified to have been infested. This action essentially thinned the stand of trees and did not result in significant visual impact. Logging of the area between the existing mill tailing fresh water bypass canal and the ultimate tailing surface elevation is underway. The harvested timber is trucked directly to a sawmill, the slash has been piled and will be burned this winter, and stumps are stockpiled for use in creation of wildlife habitat in reclaimed areas or will be burned. Henderson has provided a proposal and supporting documentation for the construction of a temporary crossing of the fresh water interceptor canal to facilitate the logging project. The crossing will incorporate a 54-inch round culvert or the equivalent arched pipe culvert. The culvert will easily pass the 29- cfs flow expected for ditch section C-D during a 200 year recurrence interval snow melt event. In fact, with a slight water head above the top of the culvert entrance, the culvert could accommodate the probable maximum snowmelt flow of 48-cfs. The culvert must be inspected on frequent intervals and maintained in a clear, free flowing condition. The Division's approval of the culvert is for a temporary