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~:~-- . , titer 090 N O y '~.1 ~~ ~~» . '~ 1876 Richard D. Lamm Governor . ~~I II~II~II~II~~ ~I~ • DEPARTMENT OF NATURAL RESOURCES David H. Getches, Executive Director MINED LAND RECLAMATION DIVISION DAVID C. SHELTON, Director December 29, 1986 Ms. Claire Semmer Environmental Specialist Twentymile Coal Company Box 748 Oak Creek, Colorado 80467 Re: Preliminary Adequacy Comments on Technical Revision No. 1, Hydrologic Monitoring Plan, Fish Creek Loadout, C-81-036 Dear Ms. Semmer: tis~ The staff evaluation of T.R. 1 has taken place. The proposed hydrologic monitoring plan for the Fish Creek Loadout facility proposes the following changes: the elimination of monitoring at two surface water sites and five alluvial sites; a decrease in parameters being monitored; and a reduction in the frequency of full suite monitoring at surface water sites from twenty-four (24) times per year to four (4) times per year. The Division has concerns regarding the first two changes which are discussed below. The Division accepts the proposed reduction on the Frequency of monitoring surface water sites with reservations. Quarterly full suite monitoring is far less likely to provide data which is representative of seasonal changes in water quality than monthly monitoring. More frequent monitoring would provide better definition of the mean and extreme water quality parameters found at each site, The reduction in frequency means that anomalous values will have a greater effect on the mean. If this becomes a problem, we may require more frequent monitoring. Please address the following Divisional concerns: i 1. The Division would like to see an evaluation made of data collected to date at the series wells across the Fish Creek alluvium. Submit graphic analyses of the alluvial water table on a seasonal basis, as well as an interpretation of the results. The original objective for monitoring at this site was to identify the seasonal recharge-discharge interactions between Fish Creek and the alluvium in anticipation of drawdowns from the underground mine. (It appears that these sites are associated with the Fish.Creek Tipple permit due to the sites' proximity to the Loadout.) Following the Division's review of the analysis an evaluation will be made about the suitability of removing those sites from the monitoring program. 423 Centennial Building, 1373 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567