63 



replenished by an inshore flow in the vicinity of the boil 

 at depth. After the mixed water spreads over the surface, 

 further mixing which takes place must be largely with water 

 in the surrounding sewage field and to a lesser extent by 

 vertical mixing with the underlying water. 

 Suppression of Effluent Boil Below Surface 



A series of calculations using various assumed conditions 

 of temperature and salinity have been compiled in Table IV, in 

 order that some limiting conditions for the equilibrium posi- 

 tions of the rising effluent may be considered. The compu= 

 tations are based on various dilutions in the proposed boil, 

 an assumed depth of discharge of 200 feet, a normal shelf 

 water salinity of 33.50 o/oo, a mixed water temperature of 

 50° to 55°F in the rising column for each chosen dilution, 

 and various surface temperatures typical of each season of 

 the year in the approximate area of the proposed outfall. 

 It is also assumed that fresh sea water will be continually 

 available at the end of the outfall, so that no appreciable 

 change in the salinity or temperature of the rising column 

 will occur after initial dilution. It is evident that, as 

 a whole, the above criteria are the optimum conditions. It 

 is probable that the temperature of the rising effluent will 

 be close to those assumed, but its salinity may be higher. 

 It is also probable that the approach of new shelf water 

 will not be fast enough to prevent the mixing of previously 

 diluted sea water with the effluent, causing a lighter mass 

 than is here assumed. In any event, the calculations indicate 

 times at which suppression may possibly be expected. 



