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1990, 1991 AND 1992 AHR REVIEW <br />Page 4 <br />conclusion? Is the flume for Sylvester Gulch situated so that <br />it will monitor possible impacts from the refuse pile? The <br />level of iron, conductivity, TDS, and manganese has exceeded <br />baseline data for GP-1, and in some cases the increase is <br />significant. Please also explain the sporadic results from <br />GP-1. <br /> MCC's response: <br /> ~)- <br /> The construction and reclamation of the waste pile utilizes~F~'' <br /> the Best Construction Techniques Available (BCTA) for ~~'~;•~~ <br /> n <br />minimizing the hydrologic impacts associated with the mine's ~ <br /> waste. These techniques include the routing of water around <br /> the refuse disposal area, quickly diverting water off the <br /> pile, and compacting the waste to 90$ compaction with two-foot <br /> lifts or less to minimize the permeability of the structure. <br /> The reclamation of the pile should improve the surface water <br /> quality around the pile by limiting the exposure of the waste <br /> to surface runoff. w <br /> ti <br />Historic baseline data for GP-1 was re-evaluated in ~ <br /> conjunction with the 1993 AHR. This data shows the TDS and ~y <br /> total manganese levels being within the range of the baseline -~ <br /> data. Specific conductance appears to approximately twenty o> <br /> percent higher than the maximum recorded baseline value. MCC ~~ <br /> cannot account for the discrepancy between the TDS and the <br /> ~ <br />specific conductance. Total iron concentrations in two cases <br /> ~ <br />in 1992 exceeded the baseline range. The 1991 and 1992 iron ~ <br />~ <br />~ <br /> , <br />concentrations in GP-1 are measured as total iron, and 'h <br /> , <br />concentrations appear to be directly correlated with the ~~~~4 <br /> amount of total suspended solids in the sample. TR-71~ ,~~' <br /> proposes to discontinue the monitoring of total metals~in t`' <br /> ground water wells in favor of monitoring the dissolved form. <br /> ~~ ~~~ Sce ~v~ <br /> Furthermore, MCC is monitoring three other wells on the refuse <br /> pile, which have never had adequate water for sampling. There <br />I- is very little groundwater within the lower refuse pile. <br /> <br />y <br />~~ Surface water from the refuse pile is diverted west to MB-2R, 1 f <br />d <br />t <br />h fl <br />l <br />t <br />t <br />l <br />i <br />~ <br />y(. ups <br />ream ~; ~.~ <br />ume <br />s <br />oca <br />e <br />er Gu <br />c <br />formally MB-6. The Sylves <br />+ <br />q <br />~ <br />~Q <br />~~ from most of the refuse pile and east of the pile. The <br />1 <br />. <br />~ appropriate surface water station to examine would be the .~~ ~: <br />~ <br />~ lower station of the North Fork of the Gunnison River. The <br />~~ 1992 data does not show a consistent, significant difference ~~ p„~ <br />1~~ in chemical parameters between the two sites. ~ h '^~ <br />~t What is your opinion on their response to the question? y~~~ <br />w <br /> N~ <br />6. My question (#lo, Miscellaneous): <br />S <br /> u <br />