81_ 



The remaining July 1994 REMOTS® photographs show the majority of the NHAV 

 93 mound is recovering well from the disposal activity. Stage I assemblages are known to 

 be present at 12 of 13 stations with progression into Stage II and Stage III communities at 

 the fringes of the mound (400 m and 600 m away from the center). The majority of the 

 RPD depths within the NHAV 93 CDM are above 0.5 cm. 



The CDM used for capping operations over the NHAV 93 mound was dredged 

 from four individual locations within New Haven Harbor: the Outer Federal Charmel 

 (Stations E-J), Northeast Petroleum, Lex Atlantic/Gateway Terminal, and Wyatt, Inc. 

 (Morris et al. 1996). Sediment samples from these locations were analyzed for grain size 

 distribution, TOC, trace metals, and PAHs prior to capping operations to insure their 

 suitability for use as CDM. The complete results of these analyses can be found in 

 Appendix F, with summary values available in Appendix A, Table 13. 



During this survey, sediment samples were collected from 11 stations located over 

 the NHAV 93 mound to monitor the postcap chemical composition of the CDM. As a 

 means of quantifying the chemistry results of this survey, statistical ranges of the raw 

 average chemistry values from the pre-dredging surveys in outer New Haven Harbor were 

 used to provide the expected ranges of the average and individual TOC, grain size, metal, 

 and PAH concentrations in the NHAV 93 capping material. This range of values will be 

 referred to as the "composite cap material" throughout this discussion. In addition to this 

 comparison, chemical information on ambient values was collected at the 4500E, 2500W, 

 and the CLIS-REF disposal site reference areas. 



The results of this survey show that the average TOC, grain size (sand and fines), 

 metals, and PAH values from the cap surface generally lie well within, or are below, the 

 expected ranges of the composite cap material (Appendix A, Table 13). The average 

 values of arsenic, mercury, and LMW PAHs appear to be slightly elevated, however, the 

 average values that define the composite cap material ranges represent worst case 

 estimates. The expected range values of the cap material were derived from four data sets 

 that included a number of non-detected values (ND) (Appendix F, Tables 1-5F). In cases 

 where values were reported as below the instrument detection limits (<), the reported 

 detection limit value was used for a conservative estimate when calculating the ranges, 

 although for statistical analysis one half of the detection limit is also sometimes used 

 (Clarke 1994). In addition, the average values for the composite cap material were derived 

 from incomplete data sets (some values not available, N/A, Appendix F, Tables 1-5F). 



Metals and PAH values from both the pre-dredging and the postcap surveys were 

 also normalized to percent TOC and percent fine-grained material to allow for comparison 

 of chemical concentrations in sediments where the controlling phase (TOC and fine-grained 



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



