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<br />Mr. Marcus Middleton -2- June 9, 1992 <br />Twentymile Coal Company <br />9. Figure=41 is labeled as presenting borehole discharge information, yet <br />none is shown on the graph. <br />10. Figure 42 shows the Y axis labeled in units of gpm. Is this correct? <br />Also, the data table for 109 shows no discharge, yet the chart shows <br />constant discharge. Review of previous years' AHR reports indicates that <br />this discrepancy has been a chronic problem. The AHR must include <br />discharge and volume information for all mine discharge. Please explain <br />the confusion regarding this site and submit the appropriate data. <br />il. Logarithm scales are used for the Y axis on Figure 41 and Figure 51. <br />What visual information is TCC attempting to convey to the reviewer? <br />Anomolously high values should not be used to set the scale for graphical <br />representation of data, particularly by using a semi-log format. <br />12. Figure 27 is labeled as 1990 water year data. <br />13. From review of the No. column in the summary tables, it appears that <br />something is consistently incorrect (particularly in the alluvial wells) <br />with the method with which the raw data is being summed and averaged <br />(i.e., 12 field measurements were taken but only 9 to 11 appear to have <br />been counted for the yearly summary). Please review and provide comments. <br />14. Figure 53, plot of water level data for 006-AW-2 and site 1002, show <br />identical readings for water levels in 1991. This does not correspond to <br />the data tables. <br />15. This same discrepancy exists in Figure 20 for the 1990 data. Also, <br />008-AU-3 and site 305 had been tracking well as far as water level until <br />1991, then the alluvial well shows a runoff fluctuation yet site 305 does <br />not. Why? <br />MONITORING FREQUENCY <br />Bedrock Wells <br />TCC's approved hydrologic monitoring plan calls for a minimum of two <br />downgradient Wadge overburden wells to be monitored. It is apparent <br />after review of the data that the only wells in the Wadge that were <br />monitored during 1991 were 006-82-74C and 009-79-4. Water quality <br />information indicates 006-82-74C is contaminated by spoil water from the <br />upgradient surface mining activity. Review of Map 13, which represents <br />the piezometric surface of the Wadge, shows this well to be downgradient <br />from longwall mining but isolated in a depression of the piezometric <br />surface. 009-79-4 is upgradient of all active mining and shows water <br />quality which is seasonally indicative of expected Wadge water quality. <br />Although unexpected circumstances were the apparent cause of the loss of <br />006-88-2 and 006-87-1, water level data as well as sampling difficulties <br />for both wells did indicate potential future problems. <br />