1985-12-22_HYDROLOGY - M1984049

• Permit No: M1984049
• IBM Index Class Name: Hydrology
• Doc Date: 12/22/1985
• Doc Name: HYDROLOGIC EVALUATION PRIDE OF THE WEST TAILINGS POND
• Media Type: D
• Archive: No

decant system as a result of operations conducted in the
• last twenty years.
PERMITTING REQUIREMENTS
The State will require a discharge permit for the seepage
south of the old pond. However, as it is liL:ely that this
discharge existed on November 6, 1975, the effective date of
the guidelines for Ore Mining and Dressing Point Source
Category. Thus the discharge should qualify as an existing
source and the effluent limitations given in Table No.S
should apply, except that the state pH limitation of 6.5-9.0
would supercede that given in Table No.5. If, however, the
old pond discharge were included in a new source
classification for the entire mill, then no discharge would
be permitted, e>:cept the excess between annual precipitation
input and evaporation removal. Such discharge would have to
meet EPA effluent limitations for new source base and
precious metal mine discharges and the more restrictive
state pH standards. The EPA standards are given in Table
No.6. In either case the effluent would require treatment
prior to discharge.
The federal regulations define "new source" as" any
building, structure, facility or installation from which
there is or may be a discharge of pollutant, the
• construction of which commenced: (a) After promulgation of
standards of performance under section 306 of CWA which are
applicable to such source, or (b) After proposal of
standards of performance in accordance with section 306 of
CWA which are applicable to such source, but only if the
standards are promulgated in accordance with section 306
within 120 days of their proposal."
The state regulations define "commence construction" as
including "execution of, and commencement of work under
contracts for engineering design, plans and specifications
for erection, building, alteration, remodeling, improvement
or extension of treatment works and commitment to the
completion of construction of such treatment works prior tc
er.ceeding permit effluent limitations based upon facility
design and capacity, or execution of a contract for the
construction thereof defined by C.R.S. 1973,25-B-501(5)(e)
as amended".
The key words in the federal definition of "new source" are
"construction of which commenced". The key words in the
state definition of "commence construction" are "alteration,
remodeling, improvement or extension of treatment works". It
would seem likely that the State will consider the new pond
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