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1 E. J. CAVANAUGH 



2 of a deep water discharge into the harbor. By discharging 



3 through a multiple -port diffuser it is possible to obtain 



4 rapid initial mixing, possibly as high as 60 parts of 



5 seawater to one part of waste water. The mixture, however, 



6 will form a relatively thick surface field which will 



7 have a lesser tendency to remain on the surface. Thus a 

 g higher concentration of sulfite waste liquor would exist 



9 in the underlying waters. As a result, a greater depression 



10 of dissolved oxygen levels would be expected than with a 



11 surface discharge. 



12 "Normally it is considered desirable in 



13 municipal waste disposal practice to provide for as deep 



14 a discharge and as great a degree of mixing with under- 



15 lying waters as possible. In the present case, however, 



16 it appears that so doing could well cause adverse effects 



17 on the marine environment which do not exist with a sur- 



18 face discharge. For these reasons we cannot concur in an 



19 arbitrary requirement with respect to the depth of the 



20 discharge. We recommend that such a decision be based on 



21 results of a study of the dispersion characteristics and 



22 tidal currents, both surface and deep, in the vicinity of 



23 the discharge. 



24 "We trust this summary will meet your needs 

 at the forthcoming hearing. Please call if any questions 



25 



