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Permit C-81-071 1996 Annual Hydrology Report SPOIL SPRING MONITORING ~• A spoil spring monitoring program was initiated in 1986 and will be conducted annually until such time as the monitoring requirement is eliminated. According to 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 35 gallons per minute or greater, it is monitored throughout the remainder of the year in accordance with the monitoring plan. The field data for the 1996 spoil spring monitoring program is presented on Table 30. A plot of the historic flow data for Pond 87 and spoil spring 114 is presented on Figure 64. Due to pumping of Site 114 for water supply by Twentymile Coal Company, discharge from spring occurred for only a short period during the spring. The associated discharge from Pond F ceased by mid-June. None of the spoil springs at Mine 2 exceeded the 35 gpm threshold in May 1996. A full suite sample was collected as required however from the Q-Comp site as this represented largest spoil spring occurring at Mine 2. Seven additional springs with flows greater than 35 gpm were recorded at Mine 1 and Eckman Park. Spring D Comp serves as a composite sampling point for the A, B, and C series springs at Eckman Park above Pond A. The flow data indicates that the spoil springs follow the same pattern as the surface runoff: very low flow during most of the year and a very rapid increase in flow during the spring runoff followed by a moderately rapid decrease inflow. 1996 water quality data for spoil springs which were sampled for water quality are presented on Tables 31 through 43. Tables 31a through 43a provide period of record statistical summaries for the monitored sites and Tables 31 b through 43b provide period of record flow summaries for the sites. • The data for the Mine 1 spoil springs shows a maximum field conductivity value of 4250 umhos/cm (Spring 114) with a flow weighted average value of approximately 4220 umhos/cm during the 1996 water year. Spring 114 was by far the dominant influence in this area during the Annual Spring Survey. At the time this spring was sampled, the spring was being pumped with water discharged to the surface via Pond F. This discharge persisted for a relatively short period as this water was subsequently again utilized for mine water supply. The data for the Mine 2 spoil springs show a maximum field conductivity value of 3360 umhos/cm with a flow weighted average value of approximately 1430 umhos/cm during the 1996 water year. The data for the Eckman Park spoil springs show a maximum field conductivity value of 3700 umhos/cm (Spring 7) with a flow weighted average value of approximately 3040 umhos/cm during the 1996 water year. During the winter when Foidel Creek flows are dominated by spoil spring discharges, the creek's conductivity level approaches that of the spoil springs. The conductivity of the spoil springs shows temporal fluctuations that most likely reflect spoil recharge events of low TDS snowmelt. The lowest TDS concentrations in the spoil springs typically occur during the Spring snowmelt period. Figure 70 indicates that the water quality in Foidel Creek (Site 8) is influenced by the water quality of the discharge from Pond A. Pond A receives the discharge of the largest spoil springs. The spoil spring 114 discharge, which feeds site 87 (Pond F) is characterized by high dissolved solids, calcium, magnesium, sulfate and SAR compared with bedrock groundwater, other spoil springs and unaffected surface waters. Station 114 also shows comparatively high manganese and high nitrate levels. Spoil spring discharges as measured from Mine 1 and Eckman Park totaled approximately 7 . cfs during the spring survey of 1996. Due to the small size of the flows (approximately 0.31 cfs I.\DOCUMENTWHR\ECKMAN\EP96TE%T.DOC 03/28/97 Page 9