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l Mr. Steve Shuey ~ • Marsh 18. 1998 The water quality of seepage from the edit has improved significantly since removal of sulfide bearing waste rock material from the edit during re-opening activities. This material was placed behind the old bulkhead seal prior to initial edit closure. The presence of this material combined with ponding of water in the edit is believed to have resuked in the low pH observed in the seepage water. Initial seepage from the edit was around pH 3. The water quality improved after removal of the waste material es evident by the increase in pH from pH 3 to about pH 6.5. Flgure 1 shows the changes in pH that have occurred since re- opening of the edit end removal of the original bulkhead seal and waste material which was placed behind the bulkhead. Given these conditions, the objective of the edit plug is to force shallow seepage back out into the Creeds Formation rather than allowing it to preferentially flow out the portal. Since the source of the water is the Creeds Formation, this will provide along-term solution to edit seepage that closely reproduces the natural conditions that existed before mining. That is, water originating from the Creeds will continue to Flow in this formation. Since the Creeds Formation is non-mineralized, the water entering the edit and then flowing back into the Creeds Formation will be relatively unaffected by the mine. The current near neutral pH of edit seepage supports this conclusion. The natural discharge point for groundwater flowing in the Creeds Formation is unknown. However, it is possible that discharge from the Creeds Formation into Windy Gulch occurred naturally on a seasonal basis before the mine was construMed. Once the edit plug is installed, the natural flow system may be re-established and there may be some discharge from the Creeds Formation into Windy Gulch during spring end early summer. As supported by tfie water quality data from the current edit seepage, the quality of such water in the Creeds Formation should be relatively good and should not be affected by the presence of the edit or edit seal. In order to confirm that the edit seal does not have a negative impact on the quality of potential ephemeral or intermittent flows in Windy Gulch, Homestake proposes to undertake a water quality sampling program in Windy Gulch. The program will include quarterly sampling of water in Windy Gulch at a point several hundred feet upstream of the confluence with Willow Creek. An old concrete flume exists at this location. Flow in Windy Gulch has been observed at this point on a more frequent basis than elsewhere below the mine site because bedrock is close to or et ground surface. Existing water quality data obtained in Windy Gulch, as included in Table 1, will be used in combination with additional date to be collected before the edit seal is constructed to provide a baseline for comparison. Should quarterly mankoring data from Windy Gulch (collected under a monitoring plan as described below) indicate an increasing trend in dissolved constituents, then additional investigation and analysis may be appropriate. Such investigations, if necessary, would be discussed and approved with the DMG prior to proceeding. In addition to sampling of water in lower Windy Gulch, visual surveys of the area around the 9360 Portal will be made quarterly to determine whether any additional surface seeps are occurring.