54 



profiling and grab sampling over the MQR mound confirm that coarse sand, pebble, and 

 cobble size grains have been recently deposited over the MQR mound. 



Further testing of SACS during field survey operations as well as during laboratory 

 conditions discovered a strong correlation between the acoustic signal remm and overall 

 depth. Due to changes in acoustic signal power ramping, the strength of the signal return 

 tends to increase (indicating a dense "hard" substrate) over a moderate to rapid increase in 

 depth (deepening). A moderate to strongly shoaling bottom (decrease in depth) will tend to 

 produce a decrease in signal strength indicative of a less dense "softer" bottom. According 

 to the limited ground-truthing data collected over NHAV 93 and MQR, SACS performed 

 well over the relatively flat bottom and constant depth (18 m to 22 m) at CLIS. The system 

 detected and displayed differences in bottom type over the various disposal mounds as 

 anticipated. However, the results over individual bottom features should be interpreted 

 relative to the slope of the mound, as well as sediment grain size. 



3.2.3 REMOTS Sediment-Profile Photography 



The REMOTS® sediment-profiling photography survey over the MQR mound was 

 conducted to delineate the new dredged material footprint, as well as to assess the benthic 

 recolonization rate of the surface sediments. Supplemental CDM was penetrated to varying 

 depths at most of the MQR mound REMOTS® stations. The benthic conditions over the 

 MQR mound were compared to the three reference areas surrounding CLIS (2500W, 

 4500E, CLIS-REF). Complete results for the July 1994 REMOTS® MQR disposal mound 

 are available in Appendix B, Table 2. 



The surface layer of the MQR mound was made up of a more heterogenous mixture 

 of sediment grain sizes. Coarse sand, pebble, and cobble size grains were evident in a 

 number of the REMOTS® photos obtained over the MQR mound (Figure 3-24 A). The 

 major mode of sediments visible at the MQR mound is still greater than 4 phi; however, the 

 larger grain sizes in the surface layers tend to skew the mean towards 2 to 3 phi. 



The original MQR mound was the product of multiple disposal projects over a two- 

 year period. This capped mound is actually a complex inter-layered mound consisting of 

 material from the Mill and Quinnipiac Rivers, as well as Black Rock and New Haven 

 Harbors (SAIC 1995). The addition of material during the most recent disposal activity is 

 evident at Station 150S, on the southern slope of the MQR mound (Figure 3-24B). Three 

 distinct strata are visible within the top 20 cm of sediment and represent various disposal 

 events in the history of MQR. 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1994 



