Tufts Point Dredging Site - Arnak Artificial Island Construction Site 



Figures 2, 3 and 4 shows the noise generated from two construction 

 locations in the Beaufort Sea area (Ford, 1977). Although not platform noise, 

 the sounds from construction activities are nevertheless associated with 

 offshore operations. 



At the Tufts Point dredging site, noise sources included a suction 

 dredge, several crew boats and tugs pushing barges into and out of the area. 

 Noise measurements were made at several ranges (90 to 4,000 m) in four 

 different directions from this site. An artificial breakwall extends 

 northwest from the site, and is the probable reason the noise was lowest from 

 that direction (Figure 2). The average noise levels from the other three 

 directions are similar in frequency and amplitude. 



Transient sounds were also recorded at the Tufts Point site. Noisy 

 couplings in the floating pipeline probably produced the short duration sounds 

 plotted in Figure 3. 



At the Arnak artificial construction site, operating machinery included 

 a suction dredge, a tending tug, a clamshell shovel and several crew boats. 

 Figure 4 shows tonal components measured from this site. The frequency band 

 and amplitudes from the Tufts Point and the Arnak site are similar. 



The author did not report any data for frequencies below 250 Hz. Either 

 they were not included if present or they were of such a low amplitude as not 

 to be detectable. 



Logistic Traffic Noise at the Tufts Point Site 



Figure 5 shows source levels for major tonal components from tugs, tugs 

 pushing barges (empty and full) and crew boats (Ford, 1977). The frequency 

 spectra and amplitudes are comparable to those shown in Figure 2. Although 

 these levels are slightly higher, this is probably a result that these sources 

 were included with those measurements for the composite sounds that were shown 

 in Figure 2. 



Semi-Submersible Platform (SEDCO J) in the North Atlantic 



Figure 6 shows source levels for low frequency tonal s from a 

 semi-submersible platform during drilling and tripping operations (Kramer and 

 Wing, 1976). These values are of a similar level as those shown in Figure 1; 



A-5 



