PERMFILE64153

• Permit No: C1980005A
• IBM Index Class Name: Permit File
• Doc Date: 6/29/2007
• Doc Name: pg 7-300 to 7-388
• Section_Exhibit Name: Tab 7 Hydrology Part 3
• Media Type: D
• Archive: Yes

state Rea.
• values can be seen at all of the ~+,-aam Bond Creek and Cow Camp
Creek monitoring sites, this increasing trend i.s not found at the
downstream Bond Creak and Cow Camp Creek sites or the Fish Creek
sites. Sulfate levels at Site 13 are very stable, and the average
sulfate value at Site 13 is lower than the average at Site 11.
Increasing sulfate levels accotmt for much of the 'IDS increases seen
at the upper Bond Creek and Caw Camp Creek monitoring sites; 'IDS
concentrations at the Seneca II Mine are P+~m~*+ed in Section
VIII.B.3.c. below ("Review of Surface Water 'IDS Values").
Surface water discharges at the Seneca II Mine are also subject to
the effluent standards established by the Colorado Department of
Health in NPDFS Permit CO-0000221. A Dopy of the current NPDFS
permit is provided in Appendix 7-5. With the exceptions at Sites 004
and 003 discussed below, no NPDES parameter excursions have occRirred
at Seneca II Mine outfalls during the five years of water quality
• monitoring ending September 30, 1991. Discharges from Pond 004 had
pH exceedences on 06/15/87 and 06/22/87 of 9.03 and 9.04,
respectively. Tne non~ong~liance pH values were attributed to an
algae bloom observe3 at Porxi 004 at the time. No subsequent pH
excursions have been measured at this site.
A noncompliance oil and grease value (214 m7/1) was recorded at
NPDES Site 003 on 05/08/91. The high oil and grease content of the
discharge was probably due to the dredging of the Truck Wash settling
pond (located just upstream from Pond 003) prior to sampling Site
003. Four water samples later collected at 003 between May 23 and
June 19, 1991 all had oil and grease values below the allu~+rable
c. Review of Surface Water 'IDS Values.
An increase in surface water 'IDS wncentrations is an expected impact
of any surface mining operation. The "Probable Hydrologic
• Consequences" (PHC) section of the 1986 Seneca II Mine permit renewal
package provided an extensive analysis of existing hydrologic
information, and predictions of TDS values for GYassy Creek and Fish
7-324 Revised 12/02/93