HYDRO23461

• Permit No: M1982090
• IBM Index Class Name: Hydrology
• Doc Name: RATIONALE CAMP BIRD MINE CHIPETA MINING CORP OPERATOR OF THE CAMP BIRD VENTURE AND CAMP BIRD COLO IN
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 4. Permit No. CO-0026981
EFFLUENT LIMITATIONS, RATIONALE, AND MONITORING FREQUENCIES: (Continued)
Final limitations for cadmium, copper, lead, mercury and zinc are based on a
mass balance calculation using the following equation. The initial period
limitations are based on the BAT/BPT levels indicated in Table I.
EL = (WQS)(Q7-10 + DF) - (A)CQ7-10)> where
DF
EL =The water quality based effluent limitation (30 day avg.)
WQS =The water quality standard instream, from Table I
A =The existing ambient water quality instream in the vicinity of
the discharge point: See Table II
Q7-10 = The seven day-ten year low flow for the receiving stream = 1.9
cfs
DF =The maximum flow from the mine = 6.64 MGD or 10.27 cfs
Two calculations are shown below for an example.
EL Cadmium = (0.0012)(1.9 + 10.27) - C0.0006)(1.9) = 0.0013 mg/1
10.27
EL Zinc (0.3)(1.9 + 10.27) - (0.150)(1.9) = 0.33 mg/1
10.27
The ambient water quality concentrations are based on the following data which
were collected in Sneffels Creek at the Camp Bird Mine site on September 21,
1984 by the division. Sneffels Creek is one of two creeks (Sneffels and
Imogene) which are immediately upstream of the discharge. See figure 3 of the
permit for a diagram of the streams in the vicinity of Camp Bird Mine.
Table III
Ambient Water Quality Data
Sneffels Creek
Parameter, mg/1 at Camp Bird Mine
Cadmium
Copper
Lead
Mercury
Zinc
T. Iron
K = Less than
- = Not sampled
* = Assumed to be 0.00 mg
(Cd) 0.0006
(Cu) K0.005*
(Pb) 0.006
(Hg) -*
(Zn) 0.150
(Fe) -*
~1 for the mass balance calculation