REP35571

• Permit No: C1984062
• IBM Index Class Name: Report
• Doc Date: 2/23/1999
• Doc Name: 1998 ANNUAL HYDROLOGY REPORT
• Annual Report Year: 1998
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

• typically flowed year-round due to the discharge influences of other mines upstream of the gaging
stations. Site 700 also now typically flows year-round due to discharges associated with an upstream
irrigation diversion. As shown in Figures 15 through 20, spring runo(F continues to comprise most of
the annual flow. Tables IOB, 12B, and l3B provide period of record statistical summary information
for water levels a[ surface water monitoring sites 900, 700, and 29.
Water Quality -Water quality monitoring data for the Mine 3 surface water monitoring stations is
presented on Tables 10, I OA, 12, 12A, l3, and 13A. Per the approved hydrology monitoring program,
water quality samples were collected a[ all tJvee surface water monitoring sites during the 1998 Water
Year. Plots of historic water quality data for Foidel and Middle Creek sites are presented as Figures 21
dvough 25. Total dissolved solids concentration data Cor dte period of record at site 29 is presented as
Figure 2l. Period of record field conductivity data for sites 700, 29, and 900 is presented as Figures 22,
23, and 24 respectively. 1998 Water Year field conductivity data is plotted collectively for all three
sites and presented as Figure 25.
The historic base level field conductivity on Foidel Creek (Site 90(1, Figure 24) measured during spring
rwrotT, averaged approximately 1000 umhos/cm. From 1981 to 1994 the level steadily increased . The
overall increasing general trend was likely attributable to the effects of other mine discharges upstream
of Mine No. 3. Since 1994 the field conductivity levels appear to be decreasing and stabilizing near
2000 unilros/cm. A similar trend is apparent at Site 29 (Figure 23) although relatively lower field
conductivity values were again apparent Cor the 1998 Water Year as compared to 1993 and 1994.
Period of record field conductivity data for Site 7(10 (see Figure 22) also exhibited levels comparable to
recent years with no obvious Vend evident. Field conductivity values at this site are typically lower
than those encountered at Sites 29 and 900.
• Most monitored water quality parameters for surface water sites 700, and 29 were observed to fall
within previously established ranges for the 1998 Water Year with the exception of a new maximum
iron value recorded for site 700 during April, and a new maximum pH (lab) value recorded during
June.
SPOiL SPRING MONITORING
The spoil spring monitoring program .vas initiated in 1986 and is conducted amorally. In accordance
with the approved plan, the amwal mine wide survey is conducted during May with springs measured
for flow and field parameters. If a spring is discharging at or above 35 gallons per minute it is
monitored tlvoughout the remainder of the year in accordance with the monitoring plan. During the
1998 Water Year monitoring effort, no spoil springs were observed producing Vows sufficient to
require additional sampling {see Table 17).
NPDES DISCHARGE MONITORING
T~vo sediment ponds (Pond M3N -Site 24; Pond M3S -Site 7G) are monitored as part of the Mine 3
approved program. Pond M3N (Site 24) is located at the reclaimed area immediately north of the
confluence of Foidel Creek and Middle Creek to control runo(t from reclaimed areas of Mine No.3 west
of Middle Creek. Pond M3N (Site 24) is subject to Oie ellluent limitations detailed in NPDES Pern~it
No. COG-8511013. Pond M3S (Site 7G) is located south of the confluence and east of Middle Creek to
• control rnno(f from reclaimed areas east of Middle Creek. Pond M3S (Site 7G) is subject to the ellluent
limitations detailed in NPDES Pernrit No. CO-(1(127154.
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