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a 10-year 24-hour precipitation event without discharging. The emergency spillways will pass a 25-year 24-hour event and still maintain the required freeboard. Maintenance of the ponds includes periodic inspection to ensure the integrity of the structure. Sediment volumes are checked monthly and cleaned when 60 percent of the design sediment storage volume is attained. Runoff from the Barren Ridge and Federal Lease Areas of the mine is passed through one of two sedimentation ponds. These ponds (Nos. 004 and 005) serve to drain the runoff for at least 24 hours to allow solids to settle out. The resulting discharge is able to meet federal and state water discharge standards (NPDES limits). The Division reviewed the adequacy of the operator's sediment control system to ensure that the water quality discharge standards from these ponds will be met. The discussion of the drainage and sediment control system for the Federal Lease Area can be found in Volume I, Section 2.05-19 through 22 of the Federal Lease permit revision application. The sediment control system is displayed on Map 8. Detailed engineered designs can be found in Volume I, Exhibit 7. C. Surface and Ground Water Monitoring Ground Water Monitoring Information pertaining to ground water hydrology can be found in Section 2.04, Volume 1, of the approved reclamation only permit. Originally the permittee submitted quality and quantity data collected from October 1980 to September 1981. This information was gathered from six monitoring wells located hydrologically above, below, and within the permit area. Monitoring wells were sampled monthly for the required field parameters (pH, temperature, conductivity, and alkalinity) and quarterly for the parameters outlined in the Division's preliminary guideline for water quality. Monitoring continued over the active life of mine on a quarterly, then semi-annual, schedule until 1992 when Technical Revision No. 19 was approved and ground water monitoring was terminated. Upon further analysis, it was determined that by the Rules, ground water monitoring must continue until the Phase III bond release is issued; therefore, Stipulation No. 20 is issued. Stipulation No. 20 Resume the ground water monitoring on the alluvial wells above and below the Stollsteimer Creek AVF. Sample the wells bi-annually for the following parameters: -10-