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fragments of water of widely differing composition. This 



requires that several samples be taken simultaneously in order 



to compute an average dilution. It has also been noted that 



the dilution initially produced within the column or within 



subsidiary columns, is similar for virtually all outfalls 



examined „ The average dilutions range from 15 to 30 parts of 



sea water to one part effluent „ In deeper water there are 



indications (Whites Point) that a slightly higher initial 



dilution is achieved, probably because of the greater length 



of the turbulent column (50 parts of sea water to one part 



effluent). 



The dilutions were computed using the following formula? 



X = 122S^E!!ZMIP ^ parts sea water in 



(33,5-Seff) 100 parts mixed water 



Dilution = X 



100-X 



where X is the parts sea water per 100 parts mixed water 



Smw is the salinity of the mixed water 



Seff is the salinity of the undiluted effluent 



33 „ 5 is the salinity of normal shelf water in 

 parts per thousand 



Dilution is the parts sea water to one part effluent 



The effluent salinity (chlorinity) can be measured at the 



shore end of the outfall, the mixed water salinity (chlorinity) 



can be measured by sampling the sewage field, and the value for 



normal sea water can be obtained by statistical analyses of 



many salinity determinations of bay water at various depths and 



seasons. The resulting equation is useful for computing 



dilutions of as much as 200 to one, depending on the errors in 



