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<br />- 28 - <br /> <br />The degree of waste dilution required to <br />varies with the TLm and flow rate of the waste. <br />rate may be calculated by the following formula <br /> <br />prevent damage to fish life <br />The required dilution flow <br />(9) : <br /> <br />stream flow rate = lOO-1'Lm x waste flow rate x application factor <br />TLm <br /> <br />where TLm is expressed in percent. The application factor varies according <br />to the characteristics of waste and receiving stream; it generally has values <br />between three and ten. Its purpose is to provide sufficient water in exceBS <br />of the TLm concentration to dilute the waste to a harmless concentration for <br />fish life. <br /> <br /> TABLE XVI <br /> FISH SURVIVAL AND CHEMICAL <br /> CHARACTERISTICS OF DILUTION WATER <br />% Survival Alkalinity Hardness Dissolved No. of <br />StartinR Date 72 Hr. .Jill mR/l mR/l OXYRen,mR/l Fish <br />8-2l-60 100 5 <br />8-22-60 100 5 <br />8-24-60 100 7.6 200 245 6.6 5 <br />8-25-60 100 7.3 196 200 6.4 5 <br />8-29-60 100 7.6 212 225 3.2 4 <br /> <br />On the basis of this formula, the following estimates of the flow re- <br />quired for dilution are made, assuming the toxicity of ditch drainage to be <br />negligible. The range of flow required for dilution of yellow cake tails <br />waste to a concentration harmless to the test fish if adequate dissolved <br />oxygen levels exist in the San Miguel River is ten to 37 cfs, depending on <br />the choice of application factor. Likewise, the range of flows required <br />for dilution of Plant 5 wastes is 222 to 1332 cfs and that for red cake tails <br />dilution is 20 to 65 cfs. The range of flows thus required for dilution of <br />all three streams is 252 to 1434 cfs. This summary range does not take into <br />account any antagonistic or synergistic effects the wastes may have when <br />combined. <br /> <br />Daily flow records have been published for the San Miguel River at <br />Uravan for the period August 1, 1954 to September 30, 1959. Unpublished <br />records are available for the period October 1, 1959 to September 30, 1960. <br />Inspection of these data shows that, over the period of record, the flow <br />of the San Miguel River at Uravan has been less that 250 cfs for 70 percent <br />of the time. The maximum flow of record was 6,690 cfs, April 19, 1958. With <br />these conditions of waste discharge and streamflow, it would be very difficult, <br />if not impossible, to maintain an aquati.c habitat suitable for desirable fish. <br />