52 



channel deposits are discrete units of organic debris, shell-rich layers, and sand/gravel 

 layers that commonly occur in estuarine environments. These layers were commonly 

 recovered in cores from all three of the Royal River zones. With namral deposit 

 thicknesses ranging from 5 m to 20 m along the Maine coastline, these deposits tend to be 

 poorly sorted and may contain larger organic and sedimentary debris. 



The most commonly recovered lithologic unit, a subtidal to intertidal mudflat 

 deposit, consisted of a dark greenish gray to black organic-rich clay to silty clay. At closer 

 inspection, the unit varied from a highly detrital-rich unit in a clay matrix, to a siltier, 

 more consolidated and homogenous unit with very finely disseminated organic debris. In 

 general, the unit had fine bands of disseminated organic detritus (wood, sticks, leaves) 

 throughout, and also contained discrete sand and gravel layers. In the upper zone of the 

 river (anchorage area), the mudflat unit contained evidence for previous anthropogenic 

 activity (slag and construction debris. Section 4.1.2.2). 



The second most common lithology was a sand unit, recovered in many of the cores 

 collected from the outer reaches of the river, as well as in the bottom of several cores 

 collected in the middle to upper zones (Cores RR-1, RR-5, RR-14, and RR-16). The sand 

 flat unit was a greenish gray to gray, silty sand to sand, again with organic detrims as in 

 the mudflat unit. This unit was distinctive from the coarse, gravely sands that were 

 documented in discrete units within many of the other cores (flood or tidal chaimel 

 deposits). The sand flat deposit, dominant in the cores obtained from the mouth of Royal 

 River, was typically light gray color, due to a higher shell fragment component (mussels, 

 clams, oysters). In several cores, the fine sand unit was distinctly reflective from finely 

 disseminated mussel shell fragments (RR-21, RR-22, RR-23, RR-29). The presence of 

 thick sand throughout most of the cores obtained from the outer reaches of the river may 

 also be part of a point bar sequence (recent sand deposit) present near the confluence of the 

 Royal and Cousins River (MSPO 1983). 



At the bottom of several cores (RR-12, RR-20, RR-21) there was a distinctive 

 homogeneous gray clay that was characterized as stiff and well consolidated. This unit 

 appears to be a glacially deposited fine clay, most likely from the Pleistocene Presumpscot 

 Formation, which underlies the mud and sand flat deposits (Belknap et al. 1989). 



4.1.2 Sediment Tracer Analysis 



4.1.2.1 Clostridium perfringens 



Clostridium perfringens are microorganisms that indicate the presence of fecal 

 contamination, and were evaluated because of the location of a sewage treatment plant 

 along the Royal River. Draft results of the Clostridium perfringens analyses indicated that 

 the microorganism was present in all areas that were sampled, with the exception of the 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



