REP45258 - Laserfiche WebLink

Home Browse Search

>i~ea~ ra~ cwvc fs ~ike,~ tl.accuva~{C, • during the fall and winter. Currently however, and since approximately 1985, Sites 900 and 29 have 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 azsociated with an upstream irrigation diversion. As shown N Figures 15 through 20, spring runoff continues to comprise most of the annual flow. Tables IOB, 12B, and 13B provide period of record statistical summary information for water levels at 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, IOA, 12, 12A, 13, and 13A. Per the approved hydrology monitoring program, water quality samples were collected at all t}vee surface water monitoring sites during the 1997 Water Year. Plots of historic water quality data for Foidet and Middle Creek sites are presented az Figures 21 though 25. Total dissolved solids concentration data for the 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 az Figures 22, 23, and 24 respectively. 1997 Water Year field conductivity data is plotted collectively for all three sites and presented az Figure 25. The historic base level field conductivity on Foidet Creek (Site 900, Figure 24) measured during spring runoff, averaged approximately 1000 umhos/cm. Since 1981 the typical level has steadily increased although this trend appears to have leveled somewhat in 1996 with values ranging between approximately 1800 and 3000 umhos/cm, slightly lower than 1995. The overall increazing general trend is likely attributable to the effects of other mine discharges upstream of Mine No. 3. The irrigation season field conductivity levels at Site 900 exceeded 3000 umhos/cm during August, 1996. A similar trend is apparent at Site 29 (Figure 23) although relatively lower field conductivity values were again apparent for the 1997 Water Year az compared to 1993 and 1994. Period of record field • conductivity data for Site 700 (see Figure 22) also exhibited levels comparable to recent years with no obvious trend 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 1997 Water Year with the exception of a new maximum nitrate value recorded for site 700 during April . SPOIL SPRING MONITORING The spoil spring monitoring program was initiated in 1986 and is conducted annually. In accordance with the approved plan, the annual 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 i[ is monitored throughout the remainder of the year in accordance with the monitoring plan. During the 1996 Water Year monitoring effort, no spoil springs were observed producing flows suflicien[ to require additional sampling (see Table l7). NPDES DISCHARGE MONITORING Two sediment ponds (Pond M3N -Site 24; Pond M3S -Site 76) are monitored az pan of the Mine 3 approved program. Pond M3N (Site 24) is located at the reclaimed area immediately north of the confluence of Foidet Creek and Middle Creek to control runoff from reclaimed areas of Mine No.3 west • of Middle Creek. Pond M3N (Site 24) is subject to the effluent limitations detailed in NPDES Permit No. COG-850013. Pond M3S (Site 76) is located south of [he confluence and east of Middle Creek [o