depths above the interface at time intervals of 2.0, 4.0, 12.0, 24.0, 48.0, 

 96.0, 144.0, and 240.0 hr. Finally, for the potential capping sediment, sam- 

 ples of the supernatant were extracted with a syringe at 5.4-, 5.0-, 4.4-, 

 4.0-, 3.0-, and 2.8-ft depths above the interface at time intervals of 1.0, 

 2.0, 4.0, 8.0, 12.0, 24.0, 52.0, 120.0, and 144.0 hr. Suspended solids con- 

 centrations were then determined from the supernatants. 



Chemical Clarification Tests 



Apparatus and testing procedure 



20. The clarification testing apparatus consists of a six-paddle Phipps 

 and Bird stirrer. The test procedures involved placing six l-l beakers of 

 effluent on the mixing stand. One mixture serves as a control with no polymer 

 added; the rest are subjected to different dosages of the same polymer. The 

 mixtures are subjected to a rapid mixing phase (flash mixing), a slow mixing 

 phase (f locculation) , and a settling phase. This procedure is outlined in 

 Schroeder (1983). 



Sample preparation 



21. The composite dredged material slurry was prepared using upper 

 estuary composite sediment sample (see Report 3) . The total solids concentra- 

 tion of the sediment was 418 g/£. The slurry was produced by the addition of 

 site water obtained at the proposed dredging site. After thorough mixing, the 

 slurry was allowed to settle 24 hr to simulate the settling that would occur 

 in the primary basin of a CDF. This material was allowed to settle 24 hr 

 because the flocculant test showed little settling improvement after a 24-hr 

 period. The supernatant for testing was then collected and stored in a 55-gal 

 drum for screening polymers. Supernatant samples for polymer optimization 

 were stored in glass carboys for subsequent chemical analysis. The suspended 

 solids concentration of the supernatant after 24 hr of settling was 228 mg/£. 

 Before being placed in 1,000-ml beakers, the supernatant in the carboy was 

 thoroughly mixed. 



Preparation and screening of polymers 



22. Polymers were selected for testing based on the recommendations of 

 technical sales representatives from the respective polymer manufacturers. 

 Each sales representative made recommendations based on their experience. 

 American Cyanamid and Allied Chemical representatives also recommended that 



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