HYDRO25848

• Permit No: M1980244
• IBM Index Class Name: Hydrology
• Doc Date: 10/5/1995
• Doc Name: USE OF PAD 3 MATERIAL FOR ROAD BASE
• From: DMG
• To: BERHAN KEFFELEW
• Media Type: D
• Archive: No

• • III IIIIIIIIIIIIIIII
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanmenl o(Nalural Resources
1313 Sherman 51., Room 215 ~ly`~
Denver, Colorado 80203 IIr
Phone. [phone]
FA)i ~ (3031 831-R 106
DEPA2TMEM" OF
NATURAL
RESOURCES
Roy Romer
Governor
DATE: October 5, 1995 Esecmrve Dimclorl
M¢hael R. Long
TO• Berhan Keffelew Dfvlsion oi,ee~er
FROM: Harry Posey
RE: Use of Pad 3 material for road base.
CC&V proposes to use material from pad 3 for road base within the mine property. As I
understand it, materials from the upper 20 feet (or less) have been tested via a "contact test."
The Division has determined in the past that the Contact Test is adequate to determine potential
releases of contaminated precipitation to either surface or groundwater provided the solution
volumes mimic the water:rock ratios that would be encountered in the ordinary precipitation event.
The analytical results furnished in CC&V's letter to you of September 7, 1995, show no
groundwater exceedances. The total cyanide content is about 0.7 mg/L higher than the WAD
cyanide content, which would indicate in gross terms that the cyanide solutions contain about 0.7
mg/L Fe as Fe-cyanide. However, the Fe measurements do not back this up. The deviation is
small, but it might be useful to address as several of the WAD cyanide values exceed groundwater
standards.
The depth of sampling is not adequate to characterize the entire heap leach pad. No materials from
depths greater than the depth of sampling should be removed unless it is determined that they have
been adequately detoxified. Natural detoxification proceeds from top to base, so it is reasonable to
assume that the most thoroughly detoxified portions lie in the upper (i.e. sampled) part of the heap.
It is likely, given the current set of analyses, that greater concentrations of cyanide exist in the
deeper part of the pad.
cc: Jim Stevens
Jim Pendleton
M:\MIN\HHP\PAD3.MEM