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There is no flowing stream within the valley of Hay Gulch a[ the location of <br />the mine. Instead, an irrigation ditch has been constricted on the north side <br />of the valley to transport seasonal streamflow. Prior to diversion, the <br />stream flowed in a westerly direction on [he south side of Hay Gulch. <br />An ephemeral stream channel may have existed in the bench area of the <br />mine prior to disturbance of the site in 1941. This pre-mining channel <br />would have been located within an alluvial body in the lower portion of the. <br />mine. Runoff from larger events would occur as channel flow, whereas <br />smaller events, would primarily recharge the alluvium from side-slope <br />areas. For this reason, apost-mining channel will be reconstructed in the <br />current location of the facilities area. A review of the channel design <br />indicates it meets the requirements of Rule 4.05.3. <br />Two sediment ponds are located at the base of the facilities area to control <br />nrnoff and sediment generated within the disturbed area. Boundaries of the <br />area contributing runoff to each pond are delineated on Map C-4 in the <br />permit document. Runoff from undisturbed eastern portion of the upper <br />basin area is routed around the disnurbed area in the east ditch and passes <br />through a straw bale dike before entering Hay Gulch. Runoff from the <br />undisturbed western portions of the upper basin and the disturbed area is <br />discharged to Hay Gulch after passing through [he sediment ponds. <br />The sediment ponds have been designed to treat the runoff from the <br />]0-year, 24-hour precipitation event. Calculations used in the pond designs <br />indicate the ponds to be in compliance with the requirement s of Rule <br />4.05.6. A small in-line sediment trap will act to capture sediment from <br />high-flow events in the east ditch. The west pond receives drainage frorrr <br />the bench area through aditch/culvert system and acts as the primary <br />sediment control device for the disturbed area. It also discharges directly to <br />the alluvium of Hay Gulch. <br />Monitoring of surface water is limited to NPDF.S discharges as no other <br />streams occur within the penrrit area. Water quality of ground water is <br />monitored downgradient of the ponds to insure alluvial ground water in Hay <br />Gulch is being protected. <br />H. Transfer of Wells <br />At the conclusion of mining, the two well used in the operation will be <br />transferred back to the owners (4.05.14). <br />I. Discharge of Water into an Underground Mine <br />No surface water will be discharged into the underground mine workings <br />(4.05.15). <br />14 <br />