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., /-4 ".... .r::.. elf NPDESj Pennit No. CO-0042161 Salinity!Control Study Twentymile Coal Company ,tj, 4.2.3 Iteduction of Salt Discharge - Option 3 Option 3; proposes conStiuction of a single injection well to dispose of up to 0.5 cfs, ;lIld ' discharg~ without treatment of flow in excess of the well capacity and the pond storage. The construction of the injection well is technically feasible but it is uncertain an injection well could be; pefIl\itted and whether the Dakota Sandstone would prove suitable for injection. FurthefIl\pre, the depletion of water by deep well injection would likely require a surface water" right, whjch would be difficult to obtain if it resulted in material damage to the quantity of ' water supplying a designated Alluvial Valley Floor. Cost esti.pates for the deep injection well for were developed as for Options' I and 2. The transfer ppmp cost was obtained from vendor quotes, according to the system design criteria,. Piping cdi;ts were determined for a single injection well 100 feet from the pump ,station adjacent tb the existing sedimentation pond. Other costs were calculated using estimating methods qutiined in cost estimation handbooks and design texts, References included ~ Site WorIq & Landscane Cost Data. 12th Ed.. R.S.Means Co, Inc" 1993. The capital costof Option 3i~ $2,405,000 with annual operating costs of $94,000. Capital and operating costs are itemized i~ Table 8. Option 3 ~ould reduce salt loads by an average of 1.09 tons per day or 398 tons/year of the " total averltge of 688 ton/year, at a capital cost of $6,045 per ton over the ,first year, and ,an annual op~rating cost of $236 per ton. Since the injection system is designed to accommodate . all disch;uiges up to 0.5 cfs, the flows in Fish Creek would be depleted accordingly. The flows, saltlloads, and concentrations in Fish Creek would be not be measurably reduced during snowmelt runoff. The most ~ignificant difference between Option 3 and the other two options is the significantly lower capi(al cost. Operating costs for Option 3 would be comparable to those of Option 1 ;lIld significantl~ Idwer than for Option 2. The feasibility of permitting and constructing Option 1 is essentia)lythe same as for the other two options, since all require permitting ;lIld constructio~ of deep disposal welles) and depletion of water supplies" The feasibility <if disposing qf the discharge water via the injection well is the primary technical obstacle to this option, ''; ~ ~ ,~ :'i ~t "/0 f ~ ~J l f \ ~ , '~ AHA F'lIeuame: t4SALCN1.DOC Page 30 11:59 AM 09/29/95