14 



level beyond which the effect of the new outfall should be minimal. 

 We illustrate the effect of the effluent at a given location by the 

 percentage of time that effluent is more concentrated than 1 to 400 

 dilution is found at that location. Note that for toxics, a dilution of 

 1 to 30 meets water quality criteria and, thus, the 1 to 400 dilution, 

 which we are showing here, is 12 times more dilute than required 

 by water quality for contaminants. 



I direct your attention to panel one to your right. 



During winter the water is vertically well-mixed, and surface 

 values represent levels throughout the water column. Effluent 

 more concentrated than the 1 to 400 level from the existing outflow 

 occurs more than 80 percent of the time in a region which includes 

 all of Boston Harbor and the South Shore, as far as the North 

 River. In contrast, effluent more concentrated than the 1 to 400 

 level from the proposed outfall is found more than 80 percent of 

 the time in a much smaller region about 10 kilometers in diameter 

 offshore. For both outfall locations, effluent more concentrated 

 than 1 to 400 is found chiefly in Western Massachusetts Bay and 

 never found around Stellwagen Bank or Race Point for this four- 

 month simulation. 



I call your attention to panel two. During the summer the simu- 

 lation shows that the effluent from the existing outfall tends to 

 remain in the lighter surface layer, while effluent from the pro- 

 posed outfall tends to remain in the heavier lower layer. The figure 

 shows the 1 to 400 dilution for the existing outfall on the left at the 

 surface and for the proposed outfall at 15 meters depth on the 

 right. The areal extent of the deeper waters typically affected by 

 the proposed outfall is significantly less than the areal extent of 

 the surface waters affected by the existing outfall. As in the winter 

 months, effluent more concentrated than 1 to 400 is never found 

 around Stellwagen Bank or Race Point. 



For the first time, the numerical model is capable of represent- 

 ing the stratified summer conditions. We have produced a very 

 short video which I would like to show you this morning, which 

 gives a feel for the variability of the effluent distribution during a 

 two-month summer period. The video shows two dilution levels, 1 

 to 200 and 1 to 400. 



Mr. Studds. You think you have found a loophole in our proceed- 

 ings here, I see. 



Mr. BuTMAN. We might make it. The video shows Massachusetts 

 Bay viewed from the southeast. Boston is in the upper left center of 

 the screen and the tip of Cape Cod at the lower right center. The 

 red surface shows the boundary of the dilution contour for effluent 

 introduced at the present outfall. The areas to the left or west of 

 this surface are concentrations in effluent in excess of 1 to 200. The 

 blue surface shows the boundary for effluent introduced at the pro- 

 posed outfall. The date is shown in the upper right-hand corner. In 

 this simulation, one week takes about 10 seconds. 



So, now we will run the simulation. We are viewing the simula- 

 tion showing the 1 to 200 dilution. Each simulation for two months 

 is going to be repeated five times, so take a moment to get orient- 

 ed. For the existing outfall, concentrations of effluent in Boston 

 Harbor are always in excess of one part effluent to 200 parts sea 

 water, to the left or west of the red "curtain". The effluent spreads 



