HYDRO29057

• Permit No: M1988112
• IBM Index Class Name: Hydrology
• Doc Name: TABLE OF CONTENTS
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH. Water Quality Control Division
Ratiarnle -Page /3 Pennit No. CO-0045675
V/. TERMS AND COND/T/ONS OF PERMIT
A. Determination ojEjfluent Limitations (Cont.)
3. Calculation of Water OualiN Based Effluent U'mimtions: Amass balance equation was used to determine the effluent
limitations that would not violate the allax•able in-stream concentrations defined by dre xater quality standards (except
in the case of pH, where the limitations are set directly from stream standards or effluent regulations wirlrou[ using a
mass balance approach). The mass balance equation is:
M3Qt - b1rQr
M1 =
Qz
Where:
Q, = Upstream low flow (1 E3 or 30E3) from Part 1II.B.2
Q; = Average daily eff7uentJlow (design capacity)
Q, = Combined downstream flow (Q, + Q~
Mr = Upstream background pollutmu concentration Jrom 1/!. B.1 and Table VI-3
M, = Unknox~n; Maximum allowable effluent pollutant concentration
M~ = Marimron downstream allowable pollutant concentration (stream standard or antidegradation-based
standard)
Because of the mathematical relationship benveen Jlow, pollutant concentration and pollutant mass, concentration
limitations calculated using this method implicitly limit insrream pollutant nutsr to the rnaritnum allowable leve{. Also,
only flow and concentration limitations need to be specified in the permit. Mass limitations are not required. A
sumrtmry ojthe mass balance calculations is shorn and discussed in Section VI.A.4, as x•ell as in Table VI-3.
4. Discussion of Effluent Limitations
a) Regulations for E,Qluent Limitations: The Regulations for Effluent Limitations (Regulation No. 62), apply ro the
conventional pollutants. For this facility, the limitatons for Total Suspended Solids and OiI & Grease are based
on this regulation.
b) Federal Ejlluent Guidelines and Standards: Federal guidelines that are applicable for the Copper, Lead, Zinc,
Gold. Silver, acrd Molybdenum Ores Subcategory of the Ore Mining and Dressing Point Source Category are from
40 CPR Part 440. l02 and 440.103. These federal technology-based effluent limitations represent the degree of
reduction attainable by the application of the best practicable control technology currently available (BPT), and
the application of the best available technology economically achievable (BAT), respectively. Hox•ever, these
federal technology-based effluent limitations are onh~ applicable for active mining jaciliities.
Under tl:e Federal definition, as described in 40 CFR 440. /32, "an Active mining area" is a place where work or
other activity related to the extraction, removal, or recovery ojtnetal ore is being conducted, except, with respect
to surface mines, any area of land on or in w/rich grading has been completed to return the earth to desired
contour and reclamation work Iras begun. Reclamation work has been initiated at the BMRI San Luis Mine, and
according to this definition, it is not considered to be an Active mining area.
However, it should also be noted that the proposed metals limitations for this permit, which have been determined
from antidegradation based water quality standard mass balance equations, are more stringent than the federal
based limitations guidelines for Uie following five metals. The table below shows the federal based metals
limitations for active mining facilities.
Table V/-2 -- Federal Guidelines and Standards -For Active Mining Facilities
Parameter. me/l 30-Dav Average Lirni! Daily Maximum Limit
Totaf Cadmium 0.05 0.10
Total Copper 0.15 0.30
Total Lead 0.3 0.6
Total Mercrtrv 0.00/ 0.002
Total Zinc 0.75 1.5