REV05461

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Date: 5/1/1995
• Doc Name: APPENDIX B COPY OF PAPER ON MINE DRAINAGE IN COLO MINERAL DISTRICTS
• Type & Sequence: AM6
• Media Type: D
• Archive: No

C"c&V 60LD MNG. CO. ID-'19-689-254 FEB 02'94 23 16 Na.026 P.16
Table 3. Analytical results for selected wino dmina6cs in Colombo. Analytical techrriques-
. listed In tax[.
Sample Cu Za Cd Ni Co Pb pH S04 AI Fe Other
ppb ppb ppb ppb ppb ppb me/L mgiL me/L elemeata
LKP 54000 120000 330 140 190 130 2.6 1700 60 430 N • 7 ppm
Rgmolda 120000 10000 100 B00 700 7".0 2.9 1900 130 ~l0 A.• 0.4 yyu,,
U - 0.04 ppm
alacksnap 460000 390000 3000 21000 16000 <200 1.8 130000 5400 28000 Aa• 13 ppm;
U•3ppm:
Th - a ppm;
Ce - 6 ppm;
He-0.8ppm
MCN ]GOOD 24000 380 600 720 <3 1.9 4300 930 93 F - 710 mgJL:
U ' 90 PP"
Talc 7x00 ovuw ZyU 4U 20 10 4,4 640 2.6 2.4
Chap2 1 40 <1 10 3 <3 7.9 600 <0.1 0.01
Raw 1200 33000 130 40 50 S 6.0 600 0.4 24
Sol 40 26000 160 l0 80 1100 4.5 310 1.1 0.4 U - 0.02 ppm
Ara 90 17.000 60 ZO 40 <3 6.6 1300 25 19
Arlo 430D 30000 130 120 100 40 2.9 2300 29 120
FG 270 170000 l20 190 1TD 130 6.2 1800 0.2 87
Itak 40 20000 40 10 7 c3 6.8 380 <0.1 I2
Rub <1 20 <L <S <5 <5 7.8 3 0.1 c0.01
Carbon t l10 1 7A 3 <3 7.7 1200 <0.1 0.02
L
High-acid, extreme-metal and acid, extreme-metal
• The lowest pH values and highest meal contents we have meastnrd to date occur in open•
pit waters and waters tlraising acne dumps of the acid•sulfate eplthermal deposits at .
Sutnutitvillc (1•<g. 1). These eztttme pH and [rtetal value rt:sult because the Summitville tuts
ate ~yrito-rich but have very little buffeting capaciry in their hoar tvdca or a~sociatcd ttrintxala.
Pyate (FeS~, enargite (Cu;AeS4), covallite (CuS), and native sulfta wen deposited in zones
along which the host wallrock had been intensely acid-leached by acid magroaric gasct, lgvtns
silica, aluniu (KAl3[SCkt]2[Oli]~, kaollnite. and clays. Due to the abundance of Cu- and As-
rich sulfides, the Summitville wamrs ate tdso the riches[ in Cu and As of all drairages
measured tD date, with (fit gmater than Or subequal to Zn (huntirtds Of ppm) and Aa as high as
25 ppm. 1a addition to the 1000+ ppm sum of bee tnetala, theac waters also contain pptn- to
tens-of-ppm-lt:vels of other metals such as tare earth clemonts (itEE), U, T't4 Cr, and V, which
are indicative of extensive dissolution of both ore and wallrock minerals. Hydrogen isotope
shifts to heavy values (from near -120 to -65 pemtil SD) and coctesponding incteasea in
aqueoas chlotidt: ctxtcensadons (from less than 1 mg/L to as high as 96 mg/L) in the most
rrtecalliferous of the Stunmitviile wears (Dike 2, B-ackstnp samples) intiicste that extensive
evaporation occurred and likely coatributrd to the extreme metal concentmdans. 'The
Longfellow and Kohler tttttttels near Silverton also drain ore deposits rich in enargite with
rziatively lisle buffering capaciry in their wallrocks, and so then waters ate also quite acidic and
metal-rich. The other waters accuttirtg in this class are those that drain pyri¢-lick [trine dumps
in other deposit ea, such as mine damps at the Druid Mine near Cenral City. The high
petmeabilities of~e mine dumps enhance evaporation, petrrtit easy influx of asnoaphetic
oxygen, and provide the water with access to large amounts of sulfides for weathenng.
Even mots: extreme metal contents fZst and Cu concdntratiotts in the g/L range) ahd
acidities (pH values as low ac -3) have been documented by Alpers and Nordstrom (1991) in
watch draining underground workings of the Iron Mountain massive sulfide deposit in
California: howova, the same types of geologic consols on drainage composidtm ate present
as thoso we document in Colorado ore deposits with high-acid, extreme-[natal drainages. At
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