30 



Sections 3.2 (Biological Monitoring) and 

 3.3 (Chemical Monitoring). The available 

 data make it qualitatively clear that 

 conditions at MQR are dominated by 

 factors associated with the Black Rock 

 Harbor and New Haven sediments rather 

 than any effects caused by the previously 

 placed Mill and Quinnipiac River material. 



2.4.2 MQR Operations: Conclusions 



Continued monitoring since disposal 

 has defined more precisely the operational 

 problems at MQR, and will be discussed 

 in Section 3.0. However, in assessing the 

 operations at MQR, the following points 

 should be emphasized: 



• The inability to resolve differences 

 between disposal barge log 

 estimates and volume calculations 

 was directly affected by incomplete 

 or unavailable disposal barge log 

 records. 



• Deposition of Black Rock Harbor 

 material at the end of the disposal 

 sequence complicated analysis of 

 subsequent monitoring data at 

 MQR. 



2.5 Cap Sites 1 and 2 



In 1983, coincident with the Black 

 Rock/New Haven Harbor phases of 

 disposal at MQR, NED conducted a 

 controlled capping operation at CLIS under 

 conditions essentially similar to those 

 applied during the Stamford-New Haven 

 project in 1979. Contaminated material 

 from Black Rock Harbor was to be placed 



at CLIS at two points along the 

 northwestern margin of the site in water 

 depths of approximately 17-18 m (Figure 

 2-1). The southern mound (CS-1) was to 

 be capped with finer grained silts and clays 

 similar to those at STNH-S whereas the 

 northern mound (CS-2) was to be capped 

 with sandy silts as at STNH-N. All 

 capping material was to be obtained by 

 maintenance dredging within New Haven 

 Harbor. 



This capping operation, in combination 

 with the placement of an uncapped deposit 

 of Black Rock Harbor material at the FVP 

 mound (Figure 2-1), permitted three 

 comparisons to be made: (1) comparisons 

 with the Stamford-New Haven project; (2) 

 comparison of capped and uncapped 

 mounds (CS-1 or CS-2 vs. FVP); and (3) 

 comparison of some aspects of the 

 effectiveness of mud vs. sand sediment 

 caps as a barrier or impediment to 

 contaminant migration (Morton et al. 

 1984a). 



2.5.1 CS-1 and CS-2 Disposal 

 Operations 



Dredging of sections of Black Rock 

 Harbor and subsequent disposal at Cap 

 Site 1 began on 6 April 1983 and 

 continued through 14 April 1983 (Figure 

 2-8). NED disposal barge log records 

 indicated that approximately 33,200 m 3 of 

 sediment was placed at CS-1. Disposal 

 operations at Cap Site 2 were more 

 intermittent, with operations beginning on 

 18 April 1983 and continuing until 18 May 

 1983 (Figure 2-8). Disposal barge logs 



Sediment Capping of Subaqueous Dredged Material Disposal Mounds 



