46_ _^__ 



River during the original analysis, one of the additional cores (RR-3) was split into two 

 sections to evaluate the effect of the preservative. Results of this analysis are discussed in 

 Section 4.6 in the context of the micropaleontological analysis results. 



3.9 Tracer Analyses 



3.9.1 Sewage Tracer (Royal River only) 



Clostridium perfringens are microorganisms that naturally occur in the intestines of 

 humans and animals. Because this species can survive for long periods of time in the 

 environment, their presence in sediment may indicate fecal contamination that is several 

 years old. On the Royal River (near RR-18), a sewage treatment plant releases treated 

 effluent into the river between Wolfe's and Callen Points. Therefore, samples were 

 analyzed for Clostridium perfringens to evaluate its potential as a tracer of the Royal River 

 dredged material once deposited at PDS. 



3.9.2 Grain Size 



Grain size analyses were conducted using American Society for Testing and 

 Materials (ASTM) Method D422-63 on grab samples collected during the precap survey, 

 and cores collected during the postcap survey. Samples were sieved into size fractions 

 greater than 62.5 |am (<4 phi; sand and gravel), and less than or equal to 62.5 \xm(>A 

 phi; silt and clay). The gravel and sand fractions were subdivided further by mechanically 

 dry sieving it through a graded series of screens. The wet sieve and dry sieve fractions 

 less than 62.5 i^m (silt and clay) were combined for each sample. The silt and clay 

 fraction was then subdivided using a pipet technique depending upon differential settling 

 rates of particles. Data on grain size were converted from units of phi to units of gravel, 

 sand, silt, and clay (Wentworth 1922). 



3.9.3 Coarse Fraction 



All samples were sieved through a 0.5 mm screen (>500 /^m), dried, and weighed. 

 For the Royal River samples, a general description of the primary component and 

 secondary components if applicable, were recorded. 



3.9.4 Fine Fraction: Microfossil and Mineralogy Observations 



The samples were also sieved through a 0.063 mm screen. The fine fraction 

 sediments ( < 500 ^m and > 63 /xm ) were dried and weighed. Silts and clays ( < 63 /^m) 

 were discarded. The fine fraction samples in this document is defined as the fine-medium 

 sand component of the sediment. These were examined through the use of microscopy 

 (magnification 40 x to lOOx) to determine type and number of microfossils, as well as 

 The Portland Disposal Site Capping Demonstration Project, 1995-1997 



