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<br />• ~, ~~~ iiiir~riui~i tiu <br />STATE OF COLORADO _ _ <br />DEPARTMENT OF HIGHWAYS <br />"~A ~~' <br />4201 Easl Arkansas Ave. ~,g ; <br />Denver, Colorado 80222 ~ ~$j <br />(303) 757-9011 lpJ g <br />••'` or co~°`' <br />September 25, 1986 <br />Hr. James HcArdle <br />Mined Land Reclamation Division <br />Room 423 Centennial Building <br />1313 Sherman Street <br />Denver, CO 80203 <br />Dear Hr. HcArdle, <br />~~~~rvE~ <br />NOV 21 1986 <br />MINED LAND <br />• RECLAMAT{ON DIV1S1ON <br />We have serious concerns with Valco's mining operation north of Lamar in the <br />Arkansas River immediately downstream of our two state highway 50 bridges. <br />This pit is referred to as the Lamar North Pit with HLR permit no. 77-:i72. <br />Our first concern is with the large dike that is blocking a major poct:ion of <br />our two 568' long, nine span bridges; structure numbers L-26-D and L-21i-H. <br />Attached is a contour map showing our roadway fill, bridge Location and <br />Valco`s dike. These bridges will handle the estimated 100 year discharge of <br />40,000 cfs as published in the Hay 1982 Federal Emergency Management AE;ency <br />(FEHA) study for the city of Lamar. With Valco's dike blocking our bridge <br />opening, the flood capacity is reduced to about 8,000 cfs before causing <br />overtopping of SH 50 north of our bridges. <br />Our second concern is the high risk of structure failure that is likely to <br />occur during a major flood as a result of Valco's deep excavation within 200 <br />feet of our bridge foundations. When a flood flow increases sufficiently to <br />breech Valco's dike, flow into the pit excavation will result in rapid <br />headcutting progressing upstream under our bridges. Our bridge foundations <br />are not designed to withstand this amount of stceambed degradation. The <br />replacement value of these two bridges is over three million dollars. The <br />roadway user cost would be X26,000 per day since a ten mile detour would be <br />needed. <br />