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Runoff from approximately 14 acres of undisturbed land in dryland wheat productions, 6 acres of disturbed land and 30 acres in various stages of reclamation is routed through the existing sedimentation pond in the northeast portion of the permit area. SCC received a water right for this pond on February 9, 1982 (see Appendix G-2). Outflow from the sedimentation pond is monitored at CPDES Discharge Point 001 (Permit No. CO- 0037656). Table G-2 presents the results of weekly monitoring at the CPDES discharge point. A copy of the CPDES permit granted to SCC is included in Exhibit M. Comparison of the CPDES effluent limitations with the data presented in Table G-2 indicates that the pH, floating solids/visible foam, and oil and grease limitations and monitoring frequency requirements have been consistently met. There have been several excursions beyond the 25 mg/I total suspended solids limitation. These excursions have been caused by algal blooms which are enhanced by nutrient-rich runoff from the 14 acres of cultivated land. SCC attempted on several occasions to rectify this problem through application of copper sulfate algalcide. The problem persisted, so SCC applied for a variance from the total suspended solids limitation. A copy of the request for variance (which was subsequently granted) submitted to the Colorado Water Quality Control Division is included in Appendix G-3. As mining progressed and the pit expanded, surface drainage • from agricultural lands drained to the pit and was diluted by disturbed area runoff and ground water eliminating the algae problem, so the request for variance was withdrawn. SCC enlarged the existing sedimentation pond to accommodate the increased runoff from the expanded Phase I disturbance area. The design calculations for the enlarged pond are provided in Appendix G-1 and pond configuration and specifications are illustrated by Exhibit G-3. The enlarged pond has a storage capacity of approximately 1.2 acre-feet, which is twice the capacity of the original sedimentation structure (0.56 acre-feet). The increased storage capacity has extended water detention times, allowing organic matter resulting from algae blooms to settle out before the water is released in most cases. A manually operated dewatering device provides additional control over discharge water quality. SCC applied for and obtained a modification of the original water right for this pond to include the additional 0.64 acre-feet of storage capacity provided by the pond expansion. G-3 Revised May 1998