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REV91571
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REV91571
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Entry Properties
Last modified
8/25/2016 3:13:05 AM
Creation date
11/21/2007 11:12:50 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1988112
IBM Index Class Name
Revision
Doc Date
4/30/1999
Doc Name
COSTILLA CNTY CONSERVANCY DISTRICT CCCD COMMENTS ON MARCH 1999 REPORT MLRB BY BMRI SAN LUIS PROJECT
From
KELLY/HAGLUND/GARNSEY & KAHN LLC
To
DMG
Type & Sequence
TR26
Media Type
D
Archive
No
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<br />Ms. L. Potter <br />April 22, 1999 <br />Page 2 <br />SPECIFIC COMMENTS <br />~ Page 18, Second Paragraph <br />t~. <br /> <br />The document concludes that the RS-3 manganese data represent "natural sources of mobile <br />manganese in the vicinity o([he San Luis mine." Examination of the historic manganese data <br />presented in Figure 3-6 raises the following questions: <br />The pre-1993 high manganese values present at RS-3 do not show up at [he downstream <br />RS-2 station. What happened to the manganese? <br />The recent high manganese values observed at RS-3 coincide with the increases in <br />manganese observed at stations RS-2 and RS-5. Is this a coincidence, or were there on-site <br />disturbances that resulted in the transport of manganese to the RS-3 drainage? Could air <br />transport of manganese-bearing dust from the mine be a potential source? <br />Additional data analysts and{or field work should be performed to support this interpretation of the <br />RS-3 manganese data. <br />Page 20, Section 4.4.4.2 <br />The discussion of hydrologic barriers is limited to installing a physical barrier that inhibits the flow <br />of water out o(the West Pit. Earlier discussions (see page 20, paragraph 2) suggest that the majority <br />of the water flowing into the West Pit originates from the Rito Seco alluvium, and enters the West <br />Pit from the southeast corner. The potentiometric data presented in Figures 3-4 and A-30, and the <br />groundwater chemistry data presented in Figures 3- 8 through 3-11 suggest that inflow of <br />groundwater from the Rito Seco alluvium into the southeast portion of the West Pit continues to <br />provide a significant portion of the groundwater entering the West Pit. <br />RMC believes that the document should evaluate the practically and effectiveness of installing a <br />physical barrier(s) that inhibits the flow of water into the West Pit. While groundwater extraction <br />from the West Pit and treatment would likely still be required under this scenario, inhibiting the <br />flow of alluvial water into the pit (i.e., keeping clean water clean) may reduce the volume of water <br />requiring treatment. This would, in turn, reduce the long term O & M costs associated with the <br />pump-and-treat system. <br />Page 66, Section 6.1.2 <br />The pumping and evaporation of 1 10 gpm of groundwater for six months during the initial phase of <br />water management will result in the loss of approximately 90 acre-feet of water from the Rito Seco <br />(~ ~,'~ system. Aside from the obvious water rights implications associated with this loss, the stream <br />`.. depletions caused by [lie pumping will result in a loss of base flow to the Rito Seco. If the <br />manganese concentrations observed at RS-3 are proven to be representative of a natural source of <br />mobile manganese, then the loss of groundwater to the lower Rito Section due to the pumping <br />depletion may result in increased manganese concentrations. BMRI needs to determine the stream <br />
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