'6 



BRENTON REEF DISPOSAL SITE 



The Brenton Reef disposal site (Fig. E-l) was used primarily between 

 1967 and 1971 as the disposal area for dredging of the Providence River. Since 

 the completion of that job, no spoils have been placed on the site and it there- 

 fore provides an opportunity to examine longer term effects of spoil disposal. 



Bathymetry 



The first survey at Brenton Reef conducted under the DA M 0S program was 

 unsuccessful due to problems relating to set up of baseline and other navigation 

 criteria during the survey operation. However, the second survey in August, 

 1978 (Fig. E-2 (a-1 ) ) was successful and defined the spoil mound as a gentle rise 

 covering the western half of the disposal area. The southeast slope of this 

 mound is much steeper than the slope to the north, probably as a result of spil- 

 lage and short dumping from scows. Spoil can be found shoreward of the site 

 indicating this has occurred. 



The top of the spoil mound has a sand surface layer, covering silty spoil 



material, but the flanks have exposed mud and spoils below 29 meters. Whether 



this sand layer is a depositional feature or a lag deposit from spoil erosion 



is a question of some controversy at this time. Future work under the DAMOS 



program will be oriented toward resolving this question, however, regardless 

 of its origin, the sand now serves as a cap over the spoils. 



Currents 



Current data were obtained at the Brenton Reef site for only a short period 

 from 25 April to 15 May, 1978 and most of these data are inadequate for valid 

 interpretation. A speed-direction plot (Fig. E-3(a-b)) indicates that problems 

 similar to those incountered at the Boston Foul Ground occurred here, such that 

 direction data are invalid and speed may be considered suspect. Diver observa- 

 tions of the meter showed that the tether was tangled in the mooring line hence 



