_REVISION - M1980244 ‎(31)‎

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Name: Adequacy Response
• From: Cripple Creek & Victor Gold
• To: DMG
• Type & Sequence: AM8
• Media Type: D
• Archive: No

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!. The operator has agreed to drill a groundwater monitoring well downgradient prior to appllcallnn of
solution. to the external pond, located below the ADR building, adequate data will be provided to the
Division prior to application ojprocess Solution to thepond. This well will be another compliance
paint,~.temporary parameters will beset until S quarders of data are collected.
Responses. CCIfV has agreed to drill and install a ground water monitoring well downgradicnt ofthc Phasc I, II,
and III External Pond. This well is shown on the revised Drawing 10.1 included as Attachment 8 to this
submittal.
CRMW-3B is an existing compliance well downgradient of the Fhase I, II, and III External Pond.
CC&Vrdoes not believe that an additional full suite compliance well is necessary due to the close
proximity of the new well to CRMW-3B-63 which adequately covers the potential for monitoring the
path ofground water flows in this area. 'Therefore. CC&V proposes the new well downgradient of the
Phase Ii~,II, and III External Pond be used as a "compliance" well to monitor for potential leakage.
Furthar,CC&V proposes that the oomplianca limits for this well be a pFI in the range of 6.0 to 9.0 and a
WAT~,cyanide level of 0.2 mg/t.
J. The purpose of the LDCRS is to collect and recover any fluids, which might seep through the liner of the
pond. ~•As in the main body of the VLF, CC&V is responsible for limiting the maximum hydraulic head
of pregnant solution ors the LDCRS to 2 feet. However, proposal for monitoring ojthe maximum
solution. hydraulic head is nor presented within the text or drawings of the AM-08 application. Please
provide the rearon why piezometerr are not needed for the Phase IV OLS
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Response: Piezomctcrs will not be rcquircd for the Phase N VLF because the design contains two features
that will limit the hydraulic head in the are storage area to 2 feet or less. These are:
'1) solution collection piping, and
',~2) site grading,
Sol>?tigii collection piping will be placed within the entire ore storage area to collect and route solution
toahe'Ehase IV Pregnant Solution Storage Area (PSSA): The spacing of the solution collection piping
(75 }feet)'tvas designed using the methods set forth in McWhorter and Sunada, Ground Water Hydrolany
and Ilvdraulics, Water Resources, Publications, 1977. The solution collection pipes were sized using
Mannings equation for flow in a circular pipe. Both of these methods were used to ensure the hydraulic
head an`the liner in the ore storage area is no more than 2 feet.
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In:addition to the solution collection piping, the Phase N VLF site grading was designed to enhance
so3utibn recovery. The majority of the ore storage area is graded between 4: 1 and 2.5:1, and is capable
ofoonveying flow rates of between 0.74 to 1.17 gallons per minuu per foot (gpmlR). The maximum
solution application rate in the VLF between the solution collection pipes can be found by multiplying
thb solution application rate (0.0045 gpni/ft) by the maximum pipe spacing (75 feet), which is equal to
0.33 gpn/ft• This result shows that the site grading provides at least twice as much capacity than is
required. Therefore, hydraulic heads greater than Z feet should not form in the ore storage area.
In addition, the flow into the solution collection piping is controlled by the permeability of the drain
cover fll ("DCF'~. Saturated pertneabiliry testing was performed for the DCF material in both
Amendment Nos. 7 and 8. The testing presented in Amendment Nc. 8 showed that the permeability was
0:15, 0:15, and 0.11 etn/sec fot normal loads of 153, 305, and 450 psi. Based on these factors, the
installation of piezometers in the Phase IV OLS is not planned
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