2023-07-25_GENERAL DOCUMENTS - M1995005

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Note: If unusually dry conditions exist at or during the execution of the project, or as directed by the PROJECT MANAGER, a twenty (20) pound fire extinguisher and a large round-pointed shovel with an overall length of at least forty-eight (48) inches will be required to be on site at all times. ITEM 3.0: INSTALL MINE CLOSURES Closure of the following hazardous mine features shall include all costs associated with the work of safeguarding and revegetating the features in accordance with the 2009 General Bid Specifications and all applicable regulations. SEDIMENT CONTROL The surface of completed closures that involve ground disturbance shall be intensely roughened to minimize sediment transport. This will be done by digging gouges or trenches perpendicular to the slope over the entire surface of disturbed ground and by creating small earthen berms approximately six inches (6") in height along the downhill edge or toe of all disturbed areas. The ends of the berm shall extend beyond the area of disturbance by approximately eighteen inches (18") and tie into the uphill slope to effectively catch any sediment. Polyurethane Foam (PUF) Closure — SWS 9 This work shall consist of setting a bottom form, installing the proper volume of polyurethane foam as designated in the work list, and once the foam has cured, backfilling as specified with onsite fill material, monumentation, revegetation, and erosion control as designated and in accordance with the specifications. Closure details (depth of bottom form, volume of PUF, backfill) for each feature can be found in the following work list table. Unless otherwise noted, one drainage pipe is required for each closure and shall be install as described in Section 9.6.4. CONTRACTOR must take measures to ensure PUF does not get on any timbers or surrounding ground surface. A more detailed description of the Polyurethane Foam Closure can be found on page 9-1 of the 2009 General Bid Specifications. Monolithic Plug Closure — SWS 7 This work shall consist of pouring a four (4) feet thick concrete cap over mine shafts that have collapsed at the collar and have no apparent opening. This work includes clearing and grubbing, excavation, furnishing and placing rockfill, furnishing and installing concrete, monumentation, revegetation, and erosion control as designated and in accordance with these specifications. A more detailed description of the Monolithic Plug Closure can be found on page 7-1 of the 2009 General Bid Specifications. Backfill — SWS 2 This work shall consist of backfilling mine openings with onsite or imported fill materials, revegetation of disturbed areas, monumentation and erosion control as designated in the specifications. Mine openings may be shafts, adits, collapsed stopes or other features some of which may be small or remote requiring the use of hand labor or small equipment to complete the closure. A more detailed description of the Backfill Closure specification can be found on page 2-1 of the 2009 General Bid Specifications. Rev. 07/07/2023 Page 12 of 20