2013-11-29_HYDROLOGY - M1977493

• Permit No: M1977493
• IBM Index Class Name: Hydrology
• Doc Date: 11/29/2013
• Doc Name: Climax Mine, Robinson Seep investigations-2013 results
• From: Climax
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

Status Report; Robinson Seep Investigation Climax Molybdenum Company
As indicated above, samples collected from several wells were analyzed for iron related bacteria
in November 2013. Based on preliminary results, although iron related bacteria were detected
in all wells sampled, no clear trends were identified. Further sampling and analysis will be
undertaken.
Similar to other constituents, concentrations of manganese at shallow well EVMW -1 S are higher
than observed values within the bedrock wells, and significantly lower than concentrations in
Robinson Lake and Robinson Lake Seep. Manganese levels observed in the bedrock wells
(EVMW -1 D and EVMW -004) are likely background values and subject to fluctuation apparently
unrelated to changes in the shallow system. Trends of dissolved manganese concentrations in
Robinson Lake Seep are similar to the observed trends of sulfate, TDS, calcium and
magnesium at this location, which as illustrated in Figure 2.2, appear to be stable or decreasing
over the June through November 2013 time period. However, the observed increase in
dissolved manganese concentration in EVMW -1 S in October and November is contrary to the
declining concentrations of sulfate, TDS, calcium, magnesium, and molybdenum at EVMW -1 S.
This change in trend is also contrary to the decreasing trend of dissolved manganese
concentrations in the Robinson Lake Seep, suggesting that other conditions or factors may be
influencing manganese concentrations at this location. A stability diagram for manganese
(Figure 2.4) shows that manganese remains in the dissolved phase for the pH and Eh
conditions observed at the site. As such, the changes in redox hypothesized for iron are not
likely to be responsible for increases in manganese concentrations.
Tetra Tech, Inc November 2013 14
Total
Dissolved
Total
Sulfate
Dissolved
Date
Iron
Alkalinity
(mg/L)
Solids
(mg/0
(Mg/0
(mg/L)
11/7/2013
4.71
290
466
930
As indicated above, samples collected from several wells were analyzed for iron related bacteria
in November 2013. Based on preliminary results, although iron related bacteria were detected
in all wells sampled, no clear trends were identified. Further sampling and analysis will be
undertaken.
Similar to other constituents, concentrations of manganese at shallow well EVMW -1 S are higher
than observed values within the bedrock wells, and significantly lower than concentrations in
Robinson Lake and Robinson Lake Seep. Manganese levels observed in the bedrock wells
(EVMW -1 D and EVMW -004) are likely background values and subject to fluctuation apparently
unrelated to changes in the shallow system. Trends of dissolved manganese concentrations in
Robinson Lake Seep are similar to the observed trends of sulfate, TDS, calcium and
magnesium at this location, which as illustrated in Figure 2.2, appear to be stable or decreasing
over the June through November 2013 time period. However, the observed increase in
dissolved manganese concentration in EVMW -1 S in October and November is contrary to the
declining concentrations of sulfate, TDS, calcium, magnesium, and molybdenum at EVMW -1 S.
This change in trend is also contrary to the decreasing trend of dissolved manganese
concentrations in the Robinson Lake Seep, suggesting that other conditions or factors may be
influencing manganese concentrations at this location. A stability diagram for manganese
(Figure 2.4) shows that manganese remains in the dissolved phase for the pH and Eh
conditions observed at the site. As such, the changes in redox hypothesized for iron are not
likely to be responsible for increases in manganese concentrations.
Tetra Tech, Inc November 2013 14