2.3.1 Grain Size Analysis 



ASTM Method D422 (Table 2-1) was used for the analysis of sediment grain size. 

 Grain sizes were classified using the Wentworth classification (phi scale) which assigns 

 gravel phi values between -2 and -1, sand between -1 and +4 inclusive, silts between 4 and 

 8 inclusive, and clays greater than or equal to 9. Prior to initiating the grain size analysis, a 

 subsample (approximately 5-20 g) was taken for determination of percent total solids (% dry 

 weight) to allow for correction of percent moisture. A sieve analysis was then performed in 

 which the sample was separated into size fractions greater than 62.5 /nm (<4 phi), sand and 

 gravel, and less than or equal to 62.5 jrni (>4 phi) silt and clay. The gravel/sand fraction 

 was subdivided further by mechanically dry sieving it through a graded series of screens. 

 The wet-sieved and dry-sieved fractions less than 62.5 /mi were combined for each sample. 

 The silt/clay fraction was then subdivided using a pipet technique dependent upon the 

 differential settling rates of particles in a water column. 



2.3.2 Total Organic Carbon 



Total organic carbon was measured using a carbon analyzer (EPA Method 9060). 

 Organic carbon in the samples was converted by the analyzer to carbon dioxide (C0 2 ) and 

 the carbon dioxide measured by an infrared detector. The amount of C0 2 is directly 

 proportional to the concentration of carbonaceous material in the sample. Inorganic forms of 

 carbon (carbonate and bicarbonate) are separated from the reported total organic carbon 

 value. Total organic carbon is a measurement of organic matter (both labile and refractory) 

 in sediments. 



2.3.3 Metal and PAH Analyses 



Samples were analyzed using standard EPA procedures (Table 2-1). Cadmium and 

 Pb were analyzed by graphite furnace atomic absorption techniques and Zn by inductively 

 coupled argon plasma emission spectrophotometry (ICP). Atomic absorption techniques by 

 graphite furnace allow for low detection limits. Digestates can be heated in several stages 

 allowing removal of unwanted matrix components. Atomic absorption spectrophotometry 

 determinations are completed as single element analyses whereas analysis by ICP allows 

 simultaneous or rapid sequential determination of many different metals. The detection limits 

 associated with ICP analysis are frequently higher than those with atomic absorption 

 spectrophotometry. Polynuclear aromatic hydrocarbons were analyzed by EPA Method No. 

 8270 which utilizes gas chromatography /mass spectrophotometry (GC/MS). 



2.3.4 QA/QC 



Results submitted by the NED lab were found to be acceptable and supported by 

 appropriate documentation. Quality control checks from the NED laboratory consisted of 



Monitoring Cruise at the New London Disposal Site, June 1991 



