Attacliment Fig. 14). At 2,000 ft (610 m) from 

 the cuts, the base of the plume (as indicated by 

 the 1.5"F (0.83°C) isotherm) was 10 to 15 ft (3 

 to 5 m) below the surface (LS3 on Attachment 

 Fig. 14). 



Maximum flood 



During the maximum flood (0848 - 1019 hours), 

 strong currents carried the thermal plume to the 

 west (Attachment Fig. 11). Mixing diluted the 

 plume so that the 4°F (2.2°C) isotherm extended 

 a maximum of 2,000 ft (610 m) to the west in a 

 narrow tongue; the 1.5°F (0.83''C) isotherm was 

 observed much farther west where it appeared to 

 begin separating into multiple branches. A well 

 defined edge to the plume was defmed by a change 

 in surface water texture and a line of foam on the 

 surface; dye concentration readings dropped to 

 background levels as this line was crossed. The 

 4''F (2.2°C) isotherm extended to the bottom in 

 the vicinity of the cuts, but was confined to the 

 upper 10 ft (3 m) 1,000 ft (305 m) southwest of 

 the cut (MFl and 3 on Attachment Fig. 15). The 

 1.5°F (0.83°C) isotherm was less than 5 ft (1.5 

 m) from the surface 4,000 ft (1 ,220 m) west south- 

 west of the cuts (MF5 on Attachment Fig. 15). 



High slack 



During the high slack survey (1213 - 1308 

 hours), the thermal plume was rather evenly dis- 

 tributed about the cuts and the center was shorter 

 and broader than during previous tidal phases 

 (Attachment Fig. 12). This difference was prob- 

 ably due to the difference in tide elevations. Dur- 

 ing low slack the water elevation between the cut 

 and Long Island Sound is greatest, producing 

 higher discharge currents there than during high 

 slack; the greater currents would tend to carry the 

 plume jet further offshore. The 4''F (2.2°C) iso- 

 therm extended 2,100 ft (640 m) offshore while 

 the 1.5''F (0.83°C) isotherm was approximately 

 3,000 ft (914 m) oft" the cuts. About 125 ft (38 

 m) offshore (MSI on Attachment Fig. 16), the 

 base of the plume was 20 ft (6 m) deep and was 

 within the top 10 ft (3 m) beyond 1,000 ft (305 

 m) from the cuts. 



Maximum ebb 



During the maximum ebb survey (1434 - 1605 

 hours), the thermal plume was carried eastward 

 into Twotree Island Channel (Attachment Fig. 

 13). The 4^ (2.2°C) isotherm extended out 2,500 

 ft (762 m) to the southeast and 3,300 ft (1,006 

 m) to the northeast mto Jordan Cove. The 6°F 

 (3.3°C) isotherm closely followed the 4°F (2.2''C) 

 isotherm. The 1.5°F (0.83°C) isotherm was 

 mapped as a narrow finger extending 12,500 ft 

 (3,810 m) toward the southeast through Twotree 

 Island Channel. In Jordan Cove, the 4 and 1.5 

 °F (2.2 and 0.83°C) isotherms were limited to the 

 eastern part; no dye was detected in the northern 

 or western parts. The plume (4°F (2.2°C) iso- 

 therm) extended down 17, 13, and 4 ft (5, 4 and 

 1.2 m) at 125, 500 and 1,000 ft (38, 152 and 305 

 m), respectively, from the cuts (MEl, 2 and 3 on 

 Attachment Fig. 17). As mentioned earlier. Unit 

 1 reduced power, heat load and circulating water 

 volume usage during the morning of 26 August. 

 Because the Station was still operating at nearly 

 90% of full capacity, the survey was completed 

 after steady state had been reached and due to 

 the ideal conditions, the distributions of these iso- 

 therms are believed to be representative of con- 

 ditions during maximum ebb. 



Supplemental temperature data 

 collection 



The TempMentor data loggers were deployed 

 at a range of distances from the quarry cuts during 

 8 October through 2 November 1987. Deploy- 

 ment #3 was closest, about 1 ,500 ft (457 m) north 

 east of the cuts; deployment #4 was fartherst, 

 about 7,500 ft (2,287 m) south east of the cuts. 

 Deployments #5, #2, #7, #1 and ^6 were set at 

 intermediate and increasing distances from the 

 cuts (see Fig. 1). 



The temperatures recorded continuously during 

 the seven deployments provided location-specific 

 water temperature histories (Fig. 6), which re- 

 flected both Station operation and environmental 

 conditions (Fig. 7). During deployment #3, 



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