1999-03-31_REVISION - M1977342 - Laserfiche WebLink

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' • (Page 2) • MINE ID N OR PROSPECTING ID q M-77-342 •INSPECTION DATE 8/6/98 INSPECTOR'S INITIALS ACS OBSERVATIONS This inspection of the Henderson Mill focussed on the Henderson 2000 conveyor corridor construction project. Overall, the project is proceeding in accordance with the plan approved in amendment AM-03 to the Henderson Mine and Mill reclamation permit. Certain changes to the plan that have occurred during construction must be incorporated into the permit through the technical revision or amendment process. These changes and suggested permitting procedures are documented in this report. A trench has been excavated for underground utility installation from the substation at the haulage tunnel portal to the location of the PC2 Drive House. The previously buried outlet end of a non-functional culvert was daylighted during utility trench excavation. The operator intends to once again bury the outlet end of this culvert once utility installation has been completed. The Division envisions no adverse environmental impact from reburial of the culvert. The PC2 drive house construction was inspected. Drive House Creek has been rerouted into a culvert to facilitate the construction. The new culvert ties into an existing culvert to carry the flows under the rail embankment. Another component of the flows from the Drive House Creek drainage is carried under the rail embankment via a culvert located farther to the south. Best Management Practices to prevent siltation of Drive House Creek were in- place, including silt fence at the downgradient margins of disturbed areas, and hay bale •filters across the two Drive House Creek segments after passing under the rail embankment. A rock cut is being constructed along the rail corridor near the beginning of the PC3 conveyor segment to make room for the conveyor installation. This cut is being stabilized by rock bolting, draping and bolting of wire mesh, and application of shot creme. The conveyor cut above East Branch Reservoir was under construction at the time of this inspection, but was relatively inaccessible due to construction traffic. The construction of the cut was observed from the west side of the reservoir. Construction has not yet begun in the large wetlands south of East Branch Reservoir that must be crossed by the conveyor. The Con-6 wetland crossing was inspected. This wetland is located at Station 130+00 on the AM-03 map dated 4/5/98. The operator has installed a total of 4 CMP culverts to carry perennial and storm related peak flows in this wetland under the extensive conveyor and access road fill that is being placed at this location. It was recommended that silt fence be installed at the west (upgradient) toe of the fill slope in order to prevent siltation of the stream from runoff from the fill slope. The operator agreed to install the silt fence by 8/7/98. The large cum located on the hill south of the Con-6 wetland was inspected. The bedrock encountered in this cut is hydrochermally altered and incompetent. The operator is considering several options to stabilize the cut through this incompetent rock, including the application of shot creme. The Regulations of the Mined Land Reclamation Board specify that any rock cut that is not completely backfilled during final reclamation, must be otherwise stabilized. The Division would accept stabilization by application of shot creme, but the aesthetic issues of using shot creme for final reclamation may have to be addressed to the satisfaction of the U.S. Forest Service. The wet'-and at Station 107+00 was inspected. It was noted that the silt fence installed at the west edge of the disturbed area was not properly keyed-in. The operator stated that