3-75 



Modification of the Thermal Regime in the Harbor 



When operating at 100% capacity, the thermal load on the 

 harbor from the generating station is 2160 x 10 BTU/hr (545 Kcal/hr) . 

 Some of this discharged heat is flushed into Long Island Sound by the 

 tide, and some is transferred to the atmosphere. If harbor temperatures 

 do not rise to the temperature of the discharged water, the rate at 

 which the heat is dissipated must equal the rate at which it is intro- 

 duced into the harbor waters. Since, however, transport and dissipation 

 of the heat is a function of temperature, this equilibri\am may not be 

 reached before the heat has been mixed throughout the harbor and average 

 harbor temperatures thus raised. 



Close to the point of discharge, the transport of heat through 

 mixing with the ambient water proceeds at a very high rate in comparison 

 with the dissipation of heat through the naviface. In this area, the 

 temperature increase will be much higher than that experienced by sta- 

 tions outside the direct influence of the plume. ) 



A segmented mathematical model of New Haven Harbor was devel- 

 oped by Ebasco Services, Inc. (1971) to assess the effect of the gener- 

 ating station thermal load on average temperatures in New Haven Harbor. 

 The Harbor was divided into 36 discrete segments (Figure 3-21) and an 

 energy balance equation written for each segment. These equations 

 assessed explicitly the effect upon the time and depth-averaged temp- 

 erature of heat exchange across the air-water interface, mixing of the 

 heat load within the harbor, and the direct input of heat from New Haven 

 Harbor Station and the UI English Station (Figure 3-21) . Exchange of 

 heat with the Sound is not accounted for in the model : no heat is 

 assumed to cross any of the external boundaries of the model, which 

 include the southern boundaries of segments 33, 34, 35 and 36. This 

 means that, for the model, all the heat discharged by the power plants 

 must be dissipated to the atmosphere within the bounds of the model 

 segments. In the natural system, some of the water which leaves the 

 harbor on the ebb tide is carried away by currents in the Sound and does 



