Laserfiche WebLink
VI. FUP.THER DISCUSSION OF STIPULATION NO. 8 <br />G ra ssv Creek Alluvium Pollutant Plume Stu dv <br />As the result of a meeting betrveen representatives of the Seneca .I D!i ne and the Colorado <br />Mined Land Reclamation Division on November 4, 1985 concerning Stipulation No. 8 to the <br />Seneca I I Mine Permit C-005-81, it was decided that the Seneca Mine would nioni for the <br />movement of total dissolved solids (TDS) from the spoil:: to the Crassy Creek alluvium. <br />Monitoring would take place in the following manner, ground water wells Gk'-S3l and GN-S33 <br />rvouid be monitored on a weekly basis for r:a ter level, pH, temperature, and specific <br />conductivity. A complete water quality check would be taken on a biannual basis. Stream <br />water monitoring would continue monthly on Grassy Creek at surface water sites SW-52-1 and <br />SW-S2-2 from March through October. As a result of the collapse of Yell GW'-531 in the <br />winter of 1982, a replacement welt, GW-531-A2, was drilled in the fall of 1982. In the <br />1982 "Seneca II Mine Annual Hydrology Report", Seneca requested changing the frequency of <br />colt ection of field parameters for the two alluvial wells from a weekly to a monthly <br />basis. The request was granted and as a result, monthly monitoring began in January 1983. <br />Tables 28 and 26 present the field rvater quality parameters collected monthly for <br />GW-S31-A2 and GW'-533, respectively. In addition, biannual lab analyses of water samples <br />coliected from these two wells may be found in Appendix B. <br />fieure 2 presents fieid conductivities (corrected to 25°C) for wells GW-S33 and GW-531-A2 <br />from 1983 (when sampling procedures were standardized) to September 1986, Figures 3, 4, <br />and 5 shorv conductivities at those two wells and their adjacent streams for 1985, 1984, <br />and 1983. Review of Figures 3, 4, and 5 show that conductivities of alluvial ground water <br />exhibit seasonal variations similar to variations in the stream. The range of <br />conductivities for a well's water generally falls within the range defined for its <br />adjacent stream. Figure 2 shows these seasonal variations for the welt waters from 1983 <br />to 1986 without the stream water conductivities so that those variations are easier to <br />See. <br />Stipulation No. B basically dealt with the travel of a contamination pl une in the alluvium <br />from the Seneca II Mine. In the original permit application, PCC stated that the mige <br />would act as a point source of contamination with the plume spreading out in a typical <br />~ ~~~ Gausian concentration distribution. Five years of further study shows that the <br />1, contamination plume issues from a stream as the source. Due to the relatively hieh flaw <br />rate of surface water compared to around water, the conductivity of the stream is uniform <br />_°S <br />