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2. Ground IJater Ga to <br />a. Total Di sscl ved Solids • <br />TDS plots for ground water are provided in Appendix 7-28. Review of these plots indicate <br />stable or decte asing :rends (for wells currently being monitored) at alluvial Weil is 66 and <br />69, spoil Wells 25 and 26, Wadge overburden Well 21, Wadge coal Wells 17 and 19, and Wadge <br />underburden We11s fiPl and 11. All other wells continue to have increasing TDS trends. <br />b. Water Quality Standards <br />Tables 7-110 and 7-111 provide water quality standards for livestock and :Lrrlgat_on, <br />respective) y, compiled from the Office of Surface Mining, the Colorado Department of <br />Health, and other agencies. Table 7-112 provides a comparison of ground water quality to <br />livestock standards. The chromium standard (50 ug/11 was exceeded at two wells fer a <br />total of 2 out of 22 samples. These exceedences, which occurred ire 1980 and 1981, are <br />most likely a result of early, less accurate analytical techniques. The pH standard 16.5- <br />6.51 was exceeded at 16 wells for a total of 94 out of 268 samples. The fluoride standard <br />(2 mg/1) was e:t ce ed ed at 4 wells for a total of 89 out of 101 samples. The lead standard <br />I1 G0 ug/11 was exceeded at 2 xells for a total of <^ out of 42 samples. As with chromium, <br />the lead exceedences are most likely a result of early, less accurate analytical <br />techniques. The mercury standard (0.2 ug/11 appears io have been exceeded at 29 wells; <br />however, all of the exceedences are a result of a detection limit (0.5 to 1.0 ug/11 which <br />exceeds the standard. The TDS standard 15000 mg/1) was exceeded at 2 wells for a total of <br />15 out of 26 samples. The sulfate standard (3000 mg/11 vas exceeded at 3 wells for a <br />tc_a1 of 18 out of 59 samples. In conclusion, it should be noted that none of the <br />accifers morn tored are being pumped _'or livestock, water. The zbcae discussion is provided <br />for comparative purposes. <br />Ta rye 7-iii provides a comparison of ground water quality is _rri gation standards. The <br />cagmium standard (10 uq/1) was exceeded at 13 wells, but for only one sample from each <br />we=:. The exceedences are a result of a de:e orlon limit that exceeded the standard. The <br />ct'_eritle standard 1100 mg/11 was exceeded ac 5 wells for a tot a'_ of 31 out of 96 samples. <br />Tte pH standard 16.5 tc 6. 5) is the same as v,e livestc c}: standard and, therefore, <br />erpe r'er.ced the same number of exceed=noes as discussed in Lhe orevious pa ragtaoh. The <br />f'_acr_de standard 11.0 mg/11 was exceeded at 11 wells for a total of 124 out of 226 <br />s arpies. The iron standard 15.0 mg/1) was exceeded at 7 sites for a total of 43 out of <br />i36 samoles. The manganese standard 10.2 mg/11 was exceeded at 32 wells, This standard <br />apci'_es to soils with a pH value lower than 6.0 Inot predominant in the Seneca II <br />environs). Only 7 wells (for a total of 35 out of 39 samples) exceed a more reasonable <br />standard of 1.0 mg/1. The mclybd enum standard 110 ug/11 appears to have been exceeded at <br />'/-360 Revised 02/05/9'1 <br />