32 



2.4.2 Sediment Sampling 



The Seawolf Mound cores were split, visually described, photographed, and prepared 

 for geochemical and grain size sampling at the University of Rhode Island's Graduate 

 School of Oceanography (GSO). In both 1997 and 1998, all the cores were split, described, 

 and photographed. However, only one core from each station (13 cores per survey) was 

 used for detailed analysis. Generally, the 0-50 cm sections of the short cores were used to 

 verify the presence of the capping layer within each zone. The long cores were sampled at 

 consistent vertical intervals to examine the depth of the capping layer and potential 

 differences in the contaminant levels with depth. 



A sampling plan for analyzing the cores was developed in 1 997 based on the US 

 Navy monitoring objectives for the Seawolf Mound (Maguire 1995). The sampling plan and 

 analysis procedures were followed again for the July 1998 cores. The top 50 cm of sediment 

 from each of the short cores was composited in a stainless-steel mixing bowl, sub-sampled, 

 and placed in a series of pre-cleaned glass jars. The short core samples were analyzed for 

 grain size, Total Organic Carbon (TOC), polycyclic aromatic hydrocarbons (PAHs), and a 

 suite of trace metals including arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), 

 lead (Pb), copper (Cu), nickel (Ni) and zinc (Zn). 



The three long cores collected in each of the two years, (4 A, 6 A, and 10A, 17 A, 19 A, 

 and 23A) each were divided into five sampling intervals (Tables 2-6 and 2-7). The long core 

 samples were composited in the same manner as the short core samples and labeled 

 according to core and depth interval. The long core samples were analyzed for PAHs, trace 

 metals (Zn only), TOC, and grain size. In addition, a QC sample (NLDS QCA-replicate of 

 1 1 A) was included with the 1997 shipment to detect any inconsistencies in the laboratory 

 analyses. All archived long core samples were stored at the GSO core storage facility in the 

 event additional analyses are required. 



2.4.3 Laboratory Analysis Methods 



This section describes the methods used for sample preparation, extraction, and 

 analysis of samples. The 1997 sediment samples were analyzed by MAXIM Technologies 

 Inc. in St. Louis, MO, and also by the Woods Hole Group Environmental Laboratories 

 (WHG), in Raynham, MA. WHG was used again in 1998 for the analysis of the 

 geochemistry samples, while the sediment collected for grain size and moisture content were 

 analyzed by GeoTesting Express, Incorporated in Boxborough, MA. The methods used for 

 analysis of each type of analyte are listed in Table 2-8 and are described in detail in Test 

 Methods for Evaluating Solid Waste EPA SW-846 (USEPA 1997). Specific information on 

 data quality is discussed in Section 2.4.4. 



Monitoring Cruise at the New London Disposal Site, Seawolf Mound 1995 - 1998 



