The temperature trace reveals initial readings of 

 approximately 6.4 °C warming to an average value of 8.3°C with a 

 maximum value of about 9.8°C. Higher temperatures are detected 

 on the ebb tide as warmer waters from the shallower coastal areas 

 flow by the disposal area. 



The current direction varies in the N-S axis over the 

 tidal cycle. The peak current velocities occur on the flood tide 

 in the northerly direction with maximum values of approximately 

 40 cm/sec (Table 2-3). Table 2-3 presents the results of 

 bivariate analysis of the current data (3-HLP) revealing the 

 average current speed to be approximately 13 cm/sec. The current 

 direction is northerly for approximately 50% (sum of 29.9 and 

 18.6%, see boxes in Table 2-3) of the period and southerly only 

 22% (sum of 16.7 and 5.2%) of the period. For 65% (sum of 27.1, 

 23.8 and 13.8%) of the period, the current velocities were in the 

 range of 4-16 cm/sec. Only 13% (sum of 5.0, 3.6, 2.5, 1.3 and 

 0.4%) of the period saw velocities greater than 24 cm/sec (0.5 

 knots) . 



Figure 2-14 presents the temperature data and a current 

 stick plot for 40-hour low-pass filtered data (40-HLP) . The 

 temperature time series depicts the average values after the 

 tidal component is removed. The net, non-tidal flow in the 

 disposal area is consistently to the north-northeast quadrant at 

 a maximum of approximately 15 cm/sec. 



2.5 Discussion 



The results of the bathymetric survey did not reveal 

 the development of a disposal mound near the location of the 

 disposal buoy. Rough estimates from scow logs of the volume of 

 dredged material deposited between the September 1984 survey and 

 the present one are approximately 360,000 yd^ (275,400 m^). This 

 large volume of material would be expected to create a mound if 

 controlled point disposal was conducted. A combination of 

 factors including the depth at the disposal point (70 m) , the 

 wide scope (3 times the water depth) of buoys normally 

 established by the US Coast Guard, and, apparently, a practice of 

 depositing dredged material while the scow is underway has caused 

 the material to be spread over a large area. Disposal of dredged 

 material in a water depth of 70 m allows a significant amount of 

 water to be entrained during the convective descent phase of 

 disposal. A large percentage of the dredged material will then 

 have a lower density due to the increased water content causing a 

 slower descent and increased spreading from the initial disposal 

 location. 



Figure 2-3 shows the wide distribution of dredged 

 material detected by the side scan sonar. The outline in the 

 figure indicates the area of intermediate reflectance that 

 usually signifies thin layers of dredged material. The pattern 



