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3 <br /> f <br /> Memo-Deckler - 2 - May 5, 1986 <br /> Ole <br /> Y <br /> T Well OW-14 may be indicating dispersal of SO4 (from Mancos Shale?) <br /> in rock tunnel spoil (tailings)that is being used to pave roads. d <br /> �4 Additionally, an extremely high nitrate content is present in " <br /> samples (from blast residue?); could this also be caused by use of--� k�� <br /> 1 r 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 base that could contribute to higher <br /> a' 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; , Y /• �� <br /> �n✓', 9. Well 1-SK-3H shows a significant rise in TDS and sulfates from <br /> c y 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 /> A f,` this anomaly is found in files. For 9/20/82 7.0 ug/l mercury and <br /> for 3/18/83 49.0 mg/l 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-8 8/22/85 missed field parameters, 12/18/85 missed <br /> alkalinity, bicarbonate, pH; <br /> r 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 iti park:' <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 /> I T 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 /> 9829F <br />