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Mr. Dan T. Mathews Page Two <br />• July 8, 1982 <br />C. Theoretical Detention Time of Mixing <br />Primary mixing of the coagulant will occur within the <br />filter dam/dugout pond. The detention time for mixing <br />will vary depending on the type of coagulant being used and <br />the water flow; however, sufficient time will be available <br />in the 170 feet of Diversion Ditch "D" to allow adequate <br />mixing. <br />D. Theoretical Detention Time of Pond <br />The theoretical detention time of the sediment control <br />structure has been estimated to be 8.5 hours, as set forth <br />in Figure 4. <br />E. Expected Range in Temperature of Wastewater <br />Runoff passing through the sediment control structures will <br />result from both snowmelt and rainfall. Temperature ranges <br />of the runoff are expected to vary from just over 32°F to <br />approximately 50°F. <br />• II. Coagulant Information <br />Bear Coal Company plans to utilize Nalco 8852 or a similar <br />coagulant. <br />Nalco 8852 is a biodegradable cationic polyelectrolyte which is <br />applied in liquid form. For the sedimentation pond at the Bear <br />No. 3 operation, design volumes of the typical application rate <br />will be approximately 5 ppm or less. <br />III. Monitoring of Effluent <br />Bear Coal Company will monitor the discharge from the <br />sedimentation pond in accordance with its NPDES permit. However, <br />during the first year's monitoring, the samples taken to comply <br />with the NPDES permit will be analyzed for the parameters set <br />forth in Figure 2. Following the first year's data, Bear Coal <br />Company will file as appropriate fora reduction in the parameter <br />list. <br />IV. Sediment Monitoring <br />No toxic sediment is expected at the Bear No. 3 Mine because of <br />the minor amounts of coagulant to be used. However, prior to <br />• removal of sediment from the pond, a sample of the sediment will <br />be analyzed for the parameters shown on the attached Figure 3. <br />