2015-03-12_PERMIT FILE - C1981014A (2)

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• Based both upon available baseline information and cumulative hydrologic monitoring data, EFCI does not anticipate any significant impacts on either surface water quality or quantity from mine disturbance areas. Sedimentation ponds have been effective in reducing levels of TSS from disturbed areas runoff and to date, surface runoff has not required any additional treatment for TDS or other chemical constituents in order to meet discharge effluent limitations. Water chemistry and quality for groundwater transferred to the surface system from the Corley Well and process water from the coal preparation plant are subject to greater variances than normal surface runoff. Consequently, EFCI closely monitors and controls any associated surface discharges. Within the mine area, Clean Water Pond No. 3, and Water Treatment and Recycle Pond No. 2, provide EFCI with the flexibility to allow retention, and sampling, of both groundwater and process plant flows. With the exception of the inherent flexibility in the mine water system to route groundwater to Water Treatment and Recycle Pond No. 2, EFCI does not • treat these flows separately. In most cases monitoring of Clean Water Pond No. 3 results in a determination that the water retained form groundwater sources will meet effluent discharge requirements without treatment and will not result in any significant changes in surface water chemistry or quality. Water Treatment and Recycle Pond No. 2 operates inclosed circuit with the process water system for the coal preparation plant as described in Section 2.05.3, Operation Plan - Permit Area. Process water is treated in Pond 2 to facilitate settling of suspended solids and adjust pH as necessary. Clarified water is decanted from the pond surface and returned to the process water system. Under normal operating conditions, there is no discharge from Pond 2 to the surface water system. CJ C:\TM86MV0L.2\REC.PLN 10124/949:10em WP51 /eme 2.05.6 -38 Revised - 9/30/94