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_.~~: <br />r <br />Richard D Lamm <br />Governor <br />TO <br />FRUhI <br />SUBJECT: <br />III III III IIIIIII III 1 .- <br />999 <br />DEPARTMENTOFNATURALRESOURCES <br />D Monl¢ Pascoe. EMec ulrve Dnerlor <br />MINED LAND. RECLAMATION DIVISION <br />DAVID C. SHELTON Director <br />April 26, 1983 <br />Brian Munson <br />Joe Uliver <br />Rockcastle C any Grassy Creek Mine Permit Kenewal Application <br />Pursuant to your request, I have reviewed the above-referenced permit <br />application for items relating to the hydrology of the mine area. The <br />mine permit area is located entirely within the Grassy Creek drainage. <br />Ground water occurrence within the consolidated bedrock units that will <br />be or have been affected by mining is sparse. However, shallow ground <br />water does exist in the permit area within the alluvium associated with <br />Grassy Creek. The potential Iniyration of poor quality water from mined <br />areas into the alluvium and eventually mixing with Grassy Creek surface <br />water is considered to be the major hydrologic concern associated with <br />the mining operation. <br />The applicant has committed to monitor surface and ground water sites for <br />monthly field parameters and selected sites quarterly for other water <br />quality parameters in order to identify possible effects of mining on <br />existing water quality. The Division requests that, in addition to this <br />monitoring program, the applicant also install and monitor wells within <br />the mine pits that have been reclaimed to date, to establish the presence <br />(or absence) of water within the reclaimed spoils. These monitor wells <br />should be sampled on a quarterly basis to 1) monitor water levels within <br />the reclaimed spoils and 2) determine the water quality of spoils water <br />(if present) for comparison with water quality of shallow ground and <br />surface water associated with Grassy Creek. <br />The applicant proposes, as part of the reclamation plan, to retain the <br />sedimentation ponds associated with the mine pits for use as stock <br />watering ponds. If spoils water aquifers develop within the reclaimed <br />mine pits, contamination of the ponds could result. Monitor wells should <br />be located within the pits such that this potential contamination can be <br />evaluated. Une monitor well per reclaimed pit, placed upgradient from <br />the sedimentation pond, should be adequate to define ground water <br />conditions within the pits, and the potential for contamination of <br />surface water supplies. <br />r <br />423 Centennial Building, 1313 Sherman Street Denver. Colorado 80203 Tel. (;103) 866-3567 <br />