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~ ~. <br />Kamon Tempo does project two post-mining impacts from the mine. Water from' - <br />the flooded workings will discharge into the glacial/alluvial aquifer of <br />Ward Creek and suosequently into the creek itself. The Division thinks it <br />would be prudent to verify those projections through the monitoring of Ward <br />Creek and its alluvium. Please propose both uD and downstream monitoring, <br />alluvial and surface water sites for this monitoring of field parameters. The <br />Division would prefer to see calculations of Head development refined by <br />piezometer monitoring of the flooded workings, but will not require <br />piezometers due to the presence of worst case projections in the Kamon Tempo <br />report. <br />I prepared some estimates on water quality in Ward Creek and the <br />glacial/alluvial aquifer, as we discussed during our August 15, 1989 telephone <br />conversation. There are enclosed. If you have some better ideas on how <br />to perform these calculations, particularly the groundwater ones, please <br />propose them. As the worst case estimates are close to or exceed our salinity <br />threshold value of 0.7 mmhos/cm (page 9 of Material Damage paper), I find <br />cause to request further monitoring of Ward Creek, <br />Tne refuse piezometers were installed to monitor the development of a <br />percned aquifer within the coal refuse area. Water levels have stayed <br />relatively constant and subsequently it is acceptable at this time to <br />discontinue monitoring. The conductivity in these piezometers is very saline <br />(EC=9000 imhos/cm) and two have exhibited an acidic nature in the past. At <br />this time, the Division feels it would be premature to remove any of the <br />refuse piezometers from the site, to enable future monitoring if conditions <br />appear to cnange. <br />The Division accepts Grand Mesa's proposal to end monitoring of the coal seam <br />piezometers. <br />In summary, please modify the revision submittal as follows: <br />~1- Monitor the Carbon Ditch sites for field parameters and total <br />suspended solids (TSS) and consider modifying the frequency of <br />monitoring to twice a year f~6 peak discharge ad a surtmer storm <br />event. ° a a~ <br />2. Propose two Ward Creek surface water sites and two alluvial sites <br />to moni~or discharge from the flooded workings into the alluvium. <br />If you have any questions, feel free to contact me. <br />Sincerely, <br />~~~~%~ Gc/,~~~ <br />Catnerine W. Begej <br />Reclamation Specialist <br />CWB/en <br />8937E <br />