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<br />Renner <br />Page 3 <br />June 25, 1986 <br />3. Daily flow tables will include annual mean flow and <br />annual summation of flow volume in all future AHRs. As <br />a standard operating procedure, water quality sampling <br />is done at the same time as instantaneous flow data, <br />used to generate the hydrographs, is collected. This <br />will be made clear in future AHRs. <br />4. PCC will attempt to verify and/or calibrate the HYMO <br />model results as presented on Page 7-77 of the permit <br />in the next AHR using flow data gathered since <br />submittal of the permit. <br />5. As can be seen from Figures 1 and 2 (attached) which <br />display total cadmium and dissolved manganese <br />concentrations, respectively, versus time, exceedences <br />of receiving stream standards of 1 u g/1 for cadmium and <br />0.05 mg/1 for manganese have occurred in the past. For <br />cadmium, the majority of samples have been below the <br />detection limit of 5 ug/1, with only three instances in <br />which the concentrations were higher than 5 ug/1 but <br />still less than 10 a g/1. There appears to be no <br />decipherable pattern or reason for these higher values <br />except that they occur periodically and may simply <br />reflect normal background fluctuations in <br />concentration. For manganese, the majority of samples <br />have shown concentrations in excess of the receiving <br />stream standard of 0.05 mg/1, with numerous samples <br />showing concentrations greater than 0.5 mg/l. Again, <br />because of the lack of any apparent trend to explain <br />these high values, one must assume that the field of <br />values presented reflects normal background <br />fluctuations in concentration. <br />As a final note, it is extremely important to note that <br />surface water samples invariably contain suspended <br />sediment. As substantiated in the first Seneca II AHR <br />(1981-1982), iron concentrations were generally closely <br />tied to suspended sediment (TSS) concentration (compare <br />the TSS concentration trend of Figu Pa 31) to <br />that of iro ,~igur~-5D (Page 33) Furthermore, total <br />mium is determined by an- alysis of an acidified <br />(with HNO ) raw sample. As a result, it can be <br />expected 3Lhat cadmium ions can be "stripped" from <br />suspended sediment particles and put into solution. <br />Given a large quantity or a particular quality of <br />suspended sediment, cadmium concentrations can easily <br />fluctuate from sample to sample. <br />