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06/28/99 MON 11:00 FAX 303 452 4515 ADCO/CHEROKEE/BAYER f~J002 1 ! ~ • • i , Cooler Fnkon Laken Plt Cotitments and Responses to DMO adequacy letter dated May 19, 1999 EXHIBIT F.R£CL,AMATIQN PLAN 9. General Staadarda for Bank Sta6t7hy The measures that will be taken fur bank stability will be as follows' a.) All back511ed maaerisl will be placed is coauoLed lifts and compacted to 959'• at optimum tnolstttte dansiry seeottling to ASTM D-698 requirements. Thickness of lift and mo'istnce-detuity relationships would be detenained by lab testing. bJ Backfilled slopes will have granular mateaial phtced over the top of the compacted embankmert fo protect from wave erosion. c.) Bank slopes and highwalls will be 'cleated, grubbed and scarified with each lift prior w tieing is of the compacted slope embankment. Each IiR will overlap into 6ighwalls a miuimum of 12 inches of to compt:oent material. d.) Tlie method used to insure adequate compaction in backfilled slopes will be compaction testing with a calibrated nuclear density meter. e.) Bacldlling and compacting with the overburden, waste soils, shale, and sand spoils will be dons by moans recommended by s geotechnical ettgineEr. These could' include recommendations fm mixing soils to achieve a relatively .homogeneous embaoktnent Settlement in an embatilament this small, using the clay soils on-site, will be relatively negligible. A rough rule of thumb is 1% settlement fur total height of entbanlnnent. This would mean a 40.foot embankment would settle 0.4 feet. Most of this settlemem would Deets during construction .and would be raised back to design grade after settlement had occurred. EXHIBIT G-WATER INFORMATION 15_ Starmwater Management and dewaterfmg eootrol T}te proposed mitring operation will cotrtrol dewatering discharges from the site under the corurols'of the Colorado Department of Health through an NPDES pemtit. All water fiam dewatering operations is typically routed through small settling ponds constructed in the bottom of the excavation fur removal of sediment Additional settling capacity may be constructed at grade deprnding on the azea being worked Tlie siu of the ponds depends on the inflow rate and is based as TSS limits set by the permit. The location of the settling ponds will change as the mining operation moves, Typically, several discharge locations will ba specified iu the permit to allow for relocation. No discharges will be done without an approved permit. CoDtrol of sediment fiom stockpiles and disturbed areas will be accomplished through site grading. The areas stripped and disnrrbed.by mining will allow for proper Location of stockpiles that allow for .temporary collection of stormwater nnroff front the stockpiles.