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<br /> <br /> -, <br />". <br />Memo-Deckler <br />-2- <br />May 5, 1986 <br />7. Well OW-14 may be indicating dispersal of S04 (from Mancos Shale?) <br />in rock tunnel spoil (tailings that is being used to pave roads. <br />Additionally, an extremely high nitrate content is present in <br />samples (from blast residue?); could this also be caused by use of <br />spoil for roadbase? This may be from fertilizer residue however, <br />used in agricultural applications on fields near the mine. On one <br />inspection trip I observed high gypsum content (fracture filling) <br />of rock tunnel debris in road Dase that could contribute to higher <br />sulfate content of surface/ground water if spoil is spread over a~ <br />large area; <br />8. Well SK-3.75 water shows high metals content at 1/24/84 sampling <br />period. These are: iron, lead, and mercury. This may warrant a <br />close watch in the future; <br />9. Well 1-SK-3H shows a significant rise in TDS and sulfates from <br />6/18/84 to 9/25/85 sampling intervals, 990 to 2720 TDS and 35 to <br />1750 sulfates, respectively. Additionally, several parameters are <br />missing data from previous years sampling periods; <br />10. Well 2-SK-3H shows relatively high levels of mercury and iron that <br />were observed in previous years sampling periods, but no mention of <br />this anomaly is found in files. For 9/20/82 7.0 ug/1 mercury and <br />for 3/18/83 49.0 mg/1 iron were observed; and, <br />11. Data points missing 1985-86 sampling year: <br />a) Well OW-4L 12/18/85 missing alkalinity, bicarbonate, lab pH, <br />8/22/85 missed field parameters 9/25/85 missed lab pH; <br />b) Well OW-B 8!22/85 missed field parameters, 12/18/85 missed <br />alkalinity, bicarbonate, pH; <br />c) Well OW-11 completely missed 1985 sampling; <br />d) Well OW-14 missed alkalinity, bicarbonate and perhaps a number <br />of other significant parameters; <br />e) Well SK-3.75 1/16/86 missing field pH and Lab pH; and, <br />f) Well 3-SK-3H 8/22/85 and 9/25/85 missed pH in part. <br />Summary <br />The colluvial wells seem to be affected by high sulfate content of the eroding <br />Mancos Shale and perhaps sections of the Mesa Verde Formation. The alluvial <br />wells are probably partly influenced by the salt loading of alluvial soils <br />from irrigation and Colorado River water. And perhaps, the bedrock wells have <br />a problem at various times (seasonal?) with metals dissolved in the water; <br />especially iron, manganese, cadmium, arsenic, molybdenum and, occasionally , <br />mercury and lead. Finally, use of the rock tunnel debris that contains high <br />sulfate material and blasting residue may contribute to an increase in the <br />nitrate and sulfate content of shallow ground waters around the facility. <br />I believe that water levels in the alluvium and partly in colluvium are mostly <br />affected by the amount of precipitation in the region and river stage. I <br />didn't find much additional information to expand upon this concept in the <br />report. Also, there does not seem to be much information available (data) to <br />indicate the chemical condition of the surface waters on the site. <br />/dlm <br />n nnnr <br />