87_ 



were 71 foraminifera (27 agglutinated, 44 calcareous) in the formalin sample and 40 (13 

 agglutinated, 27 calcareous) in the methanol sample. No shelf calcareous foraminifera 

 were found in the methanol sample, while 15 Ammonia falsobeccarii were found in the 

 formalin sample. Both the methanol and buffered formalin preserved samples contained 

 five thecamoebians. As a result of this comparison, of the remaining 17 samples, only 

 those preserved in formalin were processed and analyzed for microfossil content. 



4.5 Royal River Project Area Postcap Survey 



In mid- January 1997, SAIC conducted a postcap survey, including: precision 

 bathymetry, REMOTS® sediment-profile photography, and sediment coring to assess the 

 effectiveness of the capping operations. From November 21 to December 23, 1996, the 

 clamshell bucket dredge supplied an estimated barge volume of 22,200 m^ of CDM for 

 deposition over the Royal River pseudo-UDM deposit (Section 2.1). Because the outer 

 reaches originally designated to serve as CDM were previously dredged and deposited at 

 the DG buoy (Figure 2-9), the project design had to be modified. The dredge was 

 positioned near the mouth of the Royal River to obtain capping material distinct from the 

 pseudo-UDM. The sandy sediments near the outer reaches of the river were placed over 

 the pseudo-UDM deposit as the first layers of cap, with the goal of providing an indicator 

 of the CDM/pseudo-UDM boundary. Dredging operations proceeded up the river, with 

 barges loading sediments from the middle and upper reaches of the river. The postcap data 

 presented below were evaluated with respect to this dredging sequence. 



4.5.1 Bathymetry 



SAIC performed the final bathymetric survey for the Pordand Disposal Site 

 Capping Demonstration Project on January 14, 1997. Depth difference calculations based 

 on comparisons with the November 1996 pseudo-UDM survey were used to measure the 

 changes in bottom topography resulting from the deposition of CDM. The results 

 indicated that, although some accumulation of > 20 cm was present east-southeast of the 

 PDA buoy, the volume of CDM was too small to be confidently estimated by comparing 

 these two surveys. 



To evaluate the total thickness of the deposit, including both pseudo-UDM and 

 CDM, the January 1997 CDM survey data and the February 1996 baseline surveys were 

 compared, resulting in an irregularly shaped bottom feamre approximately 200 m wide, 

 with a maximum height of 1.5 m (Figure 4-21). The bathymetry data suggested that the 

 majority of the sediment deposit accumulated 50 m south and east of the PDA buoy 

 position, probably due to a consistent disposal pattern. The footprint of UDM, shown in 

 red on Figure 4-21, generally was consistent with the location of the overall disposal 

 mound. Discrepancies between the two surveys along the two east- west oriented lobes of 

 material measured during the pseudo-UDM survey again suggest that these areas. 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



