REP28326

• Permit No: C1982057
• IBM Index Class Name: Report
• Doc Date: 12/30/1997
• Doc Name: SENECA II-W 1996 ANNUAL HYDROLOGY REPORT
• From: DMG
• To: ERICA CROSBY
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

III IIIIIIIIIIIIIIII
999
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Deparimenl of Natural Resources
1313 Sherman 51., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
TO: Erica Crosby
FROM: Jim Bume
SUBJ: Seneca II-W 996 Annual
Hydrology Report
30 December 1997
~~~
DEPARTMEM" OF
NATURAL
RESOURCES
Roy Romer
Governor
lames 5 Lo<hhead
Execmive Direarn
Michael 8. Lon¢
Division Dneaor
Erica, I have finally completed review of the 1996 AHR for Seneca II-W. Comments are not
extensive, but are included below.
Generally, the AHR is ahigh-quality document, containing the necessary infom3ation for
analysis. It could be improved by two means.
One, the operator could actually relate the results to the PHC section of the permit. Afrer all,
isn't the purpose of the AHR to track confonnance of actualy conditions with predicted?
Secondly, the operator could use the same scale on the plots where possible. Some are way out
of the range of others, but for our purposes, variation in TDS content of 100 mg/I at a given
sampling location is not significant compared to variations of 2 or 3 orders of magnitude, the
range over which we are observing changes at some locations.
These are just suggestions.
Regarding the conformance of the hydrologic system to the predictions in the PHC, 1 have a few
comments.
Surface Water
The quality of the water in the Hubberson Gulch'`system" and the Dry Creek '`system" have not
reached the high dissolved salts levels predicted in the permit. At Hubberson Gulch, the water
downstream of NPDES point 006 has increased about 2~0 mg/I, but has reached a maximum on
one occasion of only 1700 mg/I -much less than Ithe predicted post-mining concentration of
2200 mg/I. Most measurements indicate levels about 830 mg/I. At Dry Creek, the NPDES
discharge point has seen water increase from l 100 Ing/l to nearly 1 X00 mg(I, but the at the
monitoring site downstream of the confluence of that tributary with Dry Creek, the
measurements have to this point fallen within the historic range, 1000 mg/I less than predicted.
The Sage Creek "system" is actually exceeding [he TDS loading predicted. Although
concentrations measured have displayed a wide range of values, the high has reached 710 mg/I
whereas the predicted maximutn for post-mining water is 465 mg/I.