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impact the quality of groundwater. The Wadge overburden and the Twentymile Sandstone <br /> are the two major aquifers most likely to be affected by the Foidel Creek Mine. The <br /> following wells serve as the Foidel Creek Mine's groundwater points of compliance: <br /> 97013TM (Twentymile sandstone), 008-77-58 (Wadge overburden), 008-AU3 (Fish Creek <br /> alluvium), and 008-AT-1 (Trout Creek alluvium). The mine's annual hydrology reports <br /> contain long-term data from these wells. These data show Foidel Creek Mine is in <br /> compliance with the Basic Standards for Ground Water at the groundwater points of <br /> compliance. <br /> Surface water <br /> Several possible effects on the surface water system have been identified: <br /> Discharge of mine inflow water to surface water drainages <br /> Mine water discharged to the surface system will increase the conductivity, total dissolved <br /> solids (TDS), and sulfate and iron concentrations in the streams receiving the discharge. <br /> Total suspended solids, sodium adsorption ratio (SAR), and pH could also increase due to <br /> these discharges. SAR may reach up to 6.2 in Fish Creek and 3.0 in Trout Creek. Sulfate <br /> and conductivity impacts are predicted for various segments of the stream system to be <br /> affected. TR-32 approved a plan which will allow the mine to discharge considerable <br /> volumes of degraded water during high flow (high dilution capacity) and lesser or no <br /> discharge during periods of low flow (minimal dilution capacity). <br /> Lower Middle Creek—Impacts in the Lower Middle Creek from the confluence with <br /> Foidel Creek to the confluence with Trout Creek will be pronounced due to relatively <br /> small instream flows. There is no sulfate or irrigation standard over this reach. However, <br /> due to standards on Trout Creek immediately below this segment, impacts will be <br /> minimized during most times of the year. <br /> Lower Fish Creek—The potential for significant impacts to lower Fish Creek, from mine <br /> water discharge site 115 (Fish Creek dewatering facility) downstream to the confluence <br /> of Fish Creek with Trout Creek, exists. Although no sulfate standard applies over this <br /> reach, Fish Creek and adjacent alluvial valley floor areas are held to a 1500 umhos/cm <br /> material damage standard for irrigation waters. Modeling indicates that during low flow <br /> periods, the instream conductivity limit of 1500 umhos/cm could be exceeded. <br /> Therefore, the applicant has committed to maintain its mine water discharge rate from <br /> site 115 at a level which would prevent material damage (<1500 umhos/cm)by <br /> measuring upstream flow and quality and computing a discharge rate which would <br /> prevent downstream exceedance of the conductivity limit for irrigation waters. The <br /> sulfate standard for drinking water of 250 mg/l does not apply over this reach. <br /> Lower Trout Creek— The mine does not affect Trout Creek waters above the confluence <br /> of Trout Creek with Middle Creek, but the flow rate and quality of Trout Creek is <br /> affected by site 109 (portal area) discharge into Foidel Creek. Foidel Creek flows into <br /> Middle Creek upstream of the confluence of Middle Creek and Trout Creek. Modeling <br /> submitted during the TR-32 review indicates the potential for significant impact over the <br /> Foidel Creek Mine 19 August 4,2023 <br />