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• Piezometers P-5 and P-6 were installed to determine the source of water that <br />caused the bench cover material to become saturated. The source of water <br />was either surface precipitation, snowmelt and run-off or water from the <br />underlying coal waste material. P-5 is 28.2 feet deep with a bentonite seal at <br />8 feet. It was designed to measure the water level in the coal waste material. <br />P-6 was 12.2 feet deep with a bentonite seal at 2 feet on up to the surface. <br />It was designed to measure the water level in the cover material. The <br />piezometers were placed close together so it could be determined if the <br />water level in the cover material and the coal waste material were <br />independent of each other. <br />Monitoring data collected during 1990 through 1992 (see annual hydrologic <br />'reports) showed that the water levels iri the cover material and the coal <br />waste material are independent. Therefore, piezometer P-6 has served its <br />intended purpose and does not need to be replaced. <br />5. Restabilized Bench Underdrains -A network of underdrains were installed as <br />part of the bench stabilization project during 1984 and 1985. Three drains, <br />North, Middle and South, discharge any water collected in the underdrains. <br />These underdrains will be monitored quarterly for field information, pH, <br />temperature and conductivity. Results of monitoring will be submitted to the <br />Division in the annual hydrologic report. <br />B. Surface Water <br />1. Hubbard Creek -The flow and field measurements, pH, temperature and <br />conductivity, will be monitored quarterly on upstream Hubbard Creek. Field <br />measurements will be monitored quarterly on downstream Hubbard Creek. <br />Results of monitoring will be included in the annual hydrologic report. The <br />location of the monitoring points are shown-on Exhibit Z. <br />2. NPDES Discharge -Discharge from pond 5 - outfall 001 and pond 4 - outfall <br />003 will continue to be monitored according to the requirements of CDPS <br />Permit No. COG-850009. See Exhibit J. Outfall 004 was discontinued when <br />the mine was sealed. Copies of the Discharge Monitoring Reports will be <br />submitted to the Division quarterly. <br /> <br />-124a- 2/06 <br />/>7/Z-!6 <br />/1PPRovE.D 3/ly~oy <br />