HYDRO25600

• Permit No: C1982056
• IBM Index Class Name: Hydrology
• Doc Date: 3/19/1999
• Doc Name: INTEROFFICE MEMORANDUM FISH CREEK SALT LOADING ANALYSIS
• From: DMG
• To: JANET BINNS DAVID BERRY DAN HERNANDEZ
• Permit Index Doc Type: CORRESPONDENCE
• Media Type: D
• Archive: No

iii iiiiiuiiiiii iii
999
OF COLORADO
DIVISION OF MINERALS AND GEO}OGY
Department of Natural Re~ourcei
1313 Sherman 51., Room 215
Denver, Coora[lo 80203 DIVISION O F
Phone: [phone] MINERAL S
FAX: [phone] &
interoffice G E O L O G Y
R E C L A M A T I O N
MINING•SAFETY
M E M O R A N D U M __ _
Bill Owens
Governor
t0: Greg E Watcher
Janet Bim3s, Davl Dan Hernandez
K-/ ~~L ~'+ Evecubve Director
from: Kent Gorham 1 1 ~ Michael B. Long
Division Director
subject: Fish Creek Salt oading Analysis
date: March 19, 1999
I have completed a preliminary review of salt loading on Fish Creek in conjunction with the
Foidel Creek mine water discharge at site 1 1 ~, Fish Creek borehole. My review included vazious
data submitted by Twentymile Coal Company by FAX, past Discharge Monitoring Reports and
correspondence. Annual Hydrology Reports for 1995, 1996, and 1997, and the Yampa River
CHIA.
Site 16 is the uppermost monitoring site on Fish Creek above all mining inputs. The first TCC
mine input is site 1 15 at the Fish Creek borehole facility. Site 16 is monitored for flow and field
parameters 12 times during the year, from March to September, with four full suite analyses
during the year. Traditionally, flows during the irrigation period (June to September) will
decline to about 2-3 cubic feet per second (cfs) at site 16. However, during 1997 and 1998, flows
upstream were measured at considerably higher levels. Due to this recent development, a portion
of my analysis included mass balance calculations under these higher tlow conditions.
Salt loading modeling calculations were previously included over this stretch of Fish Creek as
part of the Yampa River CHIA. These calculations included average flow conditions at site 16
based on the 5 year period 1989-1993.
Attached Table A indicates salinity modeling results using a simple mass balance equation, as
estimated in the Yampa River CHIA document, over this reach of Fish Creek. With the
exception of high flow months April and May, flo+vs upstream of site 115 (Fish Creek borehole)
range fron3 I-3 cfs. Calculated conductivity values downstream ofthe Fish Creek borehole (site
] l5) range between 751-877 umhos/cm during the June-September irrigation period, below the
suspect level of 1000 umhos/cm as stated in the Division's material damage assessment
document dated December 31, 1987.
However, data collected at site 16 upstream of site 115 in the 1997 and 1998 water years
indicates significantly higher flow rates. Table B uses these higher site 16 flow rates coupled
with actual discharge information recently recorded at site 115. Estimated downstream