23_ 



was discontinued until a new company could be selected to complete the task. The PDA 

 buoy holding station over the Royal River Project Area at the disposal site was withdrawn. 



2.2.3 Expanded Royal River Project Area Baseline Survey 



In late February 1996, NAE determined that a new baseline survey was required 

 due to the disposal of the Harraseeket River material at the Royal River Project Area at the 

 PDA buoy. SAIC conducted a second bathymetric survey, in conjunction with side-scan 

 sonar imaging of the bottom, over an expanded 1950 m x 1000 m survey area. The 

 February 1996 survey occupied a larger 1.95 km^ area over the southern region of PDS in 

 an effort to better characterize the disposal site seafloor and aid in the placement of a 

 bottom-mounted instrument array deployed to collect physical oceanographic data 

 throughout the winter and spring of 1996 (McDowell and Pace 1997). In addition, a 24- 

 station. Remote Ecological Monitoring of the Seafloor (REMOTS®) sediment-profile 

 photography survey was performed over the 800 m x 800 m project area, obtaining 

 information on the composition and distribution of the Harraseeket River dredged material 

 and ambient sediments at the PDA buoy position (Section 4.3). 



2.2.4 Pseudo-UDM Dredging Operations, Fall 1996 



The contract for the completion of the Royal River dredging project was awarded to 

 Prock Marine of Rockland, ME. SAIC deployed a new disposal buoy, "PDA 96", to mark 

 the basin feature selected to receive the Royal River material. From October 1 through 

 October 17, a total of 19,800 m^ of pseudo-UDM was dredged from the anchorage area as 

 well as from the uppermost chaimel reaches, and disposed at the PDA buoy as part of 

 pseudo-UDM Phase 1 (Figure 2-9). Over the next few days, disposal operations were 

 directed to the DG buoy, northwest of the project area for material dredged from the outer 

 reach. Phase 2 of pseudo-UDM disposal began on October 28 and continued through 

 November 14, with the removal and disposal of sediments from the margins of the 

 anchorage and channel reach 18, located near the boundary between the upper and middle 

 regions, for a total of 39,500 m^ total pseudo-UDM (Figure 2-9). 



2.2.5 Royal River Project Area Precap (Pseudo-UDM) Survey 



After the second phase of pseudo-UDM deposition, disposal operations were directed 

 to the DG buoy, and a detailed survey of the small pseudo-UDM mound was conducted 

 prior to capping (Figure 2-6). The precap survey consisted of an 800 m x 800 m 

 bathymetric survey, REMOTS® sediment-profile photography, and sediment grab sampling 

 at the disposal site in November 1996. SAIC compared bathymetric and REMOTS® data 

 obtained during the pseudo-UDM survey operations with the February 1996 baseline 

 datasets to determine mound height, size, and shape, as well as distribution of dredged 

 material within the project area. 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



