2012-03-07_HYDROLOGY - C1981033 - Laserfiche WebLink

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Sandra Brown March 7, 2012 Page 8 BCC is required to submit an Annual Hydrology Reports (AHR) to the Division in the beginning of each calendar year for the previous year. Based on our review of these reports it is evident that the water discharging from the hillside seep is of relatively good quality. BCC samples upstream and downstream surface water monitoring stations on the North Fork of the Gunnison River for semi - annual field and laboratory analyses, as well as annual full suite analyses. These sample results show that the mine including discharge from the hillside seep have not had a significant negative impact on the river. To illustrate this point I compared the upstream and downstream sample data presented in the 1996 AHR with that of the most recent data available data from the 2010 AHR (BCC has not yet submitted the 2011 AHR). These comparisons are given in Attachment 5. The 1996 data show water quality results prior to the development of the seep (seep first developed in November 1997). If the seep which continues to flow was having a serious impact on the river it would be evident in the more recent sample results. As can be seen from the data there is virtually no difference in water quality from pre -seep development to present day. Also there are only minimal differences between upstream and downstream results for both timeframes. In reviewing the field and laboratory analysis presented in the 2010 AHR (the Division has not received the 2011 AHR), the Bear No. 3 Mine had no significant deleterious effect on the North Fork of the Gunnison River during the 2010 reporting period. The results of the hillside spring water and the hillside spring water treatment pond sampling show that the treatment pond was reducing iron concentrations in the spring water and that iron concentrations were in compliance even before treatment. The seep water flows through a very small wetland area containing cat tails before being piped to the treatment pond. There is not a significant amount of iron in the discharge. Be that as it may, the level is being further lowered due to the action (uptake) by the cat tails. There appears to be no settling out of the iron by the treatment pond. There may be some precipitation, due to oxidation, but that would be readily visible as "yellow boy ". The outflow of the treatment pond shows an increase in pH above the levels seen in grab samples from the seep discharge. This could possibly be due to the cat tails removing constituents in the seep water that would normally lower pH, thereby increasing pH in the treatment pond. TSS values also were in compliance, but generally increased after flowing through the treatment pond. There was no apparent trend with TDS values before and after pond treatment. All of the WET testing of the hillside spring water and the discharge from the hillside spring water treatment pond passed. The CDPS Discharge Monitoring Reports (DMRs) are available and were reviewed for 2011 for the treatment pond outfall. The average flow from the pond was calculated to be 3.6 gpm utilizing all values for 2011. The pond receives precipitation, snowmelt and runoff, and probably some inflow from the underlying alluvium. The pond discharges constantly and it is expected that discharge from the treatment pond is greater than the discharge from the hillside seep. The treatment pond outflow was in compliance with all CDPS limits except for pH which was slightly elevated as described above. To illustrate what effect, if any the seep water would have if directly discharged to the North Fork of the Gunnison River, I did a simple mass balance equation using iron and temperature data for the seep combined with the North Fork of the Gunnison River water using data taken from the upstream sample site. The most recent available data are utilized from the 2010 AHR. In order to evaluate the potential impacts of the seep discharge, it is necessary to combine the