Characterization and Bench-Scale Testing

Characterization and Bench-Scale Testing

Cell 5 characterization and bench-scale testing

The three 19-L (5-gal) samples taken from along the truck dump were mixed

together (Buckets 1, 2 and 3 identified hereafter as Bulk 123 composite) and

homogenized. The two 19-L (5-gal) samples taken along the dike (Buckets 4 and

5 identified as Bulk 45 composite) were also combined and homogenized. Wet

chemistry, moisture content, and particle size distribution were evaluated on both

composites. Because these parameters were relatively comparable for the two

composites, one was selected for fractionation testing, rather than compositing

the total volume. Bulk 123 was selected because of the greater accessibility of

the area from which those buckets were taken, and the greater likelihood that

they would be excavated. The cores were extracted from the plastic tubes, and

samples were taken for water content analysis.

Particle size analysis. Subsamples of the Bulk 123 and Bulk 45 composites

were analyzed on the Coulter particle size analyzer. Both composites contained

over 90 percent fines.

Bulk sediment chemistry. The Bulk 123 composite and Bulk 45 composite

were analyzed for polychlorinated biphenyls (PCBs), polycyclic aromatic

hydrocarbons (PAHs), metals, total organic carbon (TOC), total recoverable

petroleum hydrocarbons (TRPH), and oil and grease (O&G) (the latter three

being potential indicator compounds). Results are summarized in Table 1.

Concentrations were comparable for all analytes for both composites.

Water content analysis. The core samples (44 total) were analyzed in

duplicate for water content (w = (Mwater/Msolids)*100) by oven drying. The

average water content was 112.4 24.6 percent. Water content of the Bulk 123

and Bulk 45 composites averaged 98.7 and 82.2 percent, respectively.

Fractionation testing. Approximately 10.5 kg (wet weight) of the Bulk 123

sample was wet sieved through a 75-m sieve for analysis of the sand (>75 m)

and fines (< 75 m) fractions. The resultant slurries were centrifuged and the

solids retained for particle size and chemical analysis. Both fractions were

analyzed on the Coulter LS100 Particle Size Analyzer to determine the efficiency

of the separation. The results (Table 2) show that the fines were not very

effectively removed from the sand. Further separation of the clay and silt from a

subsample of the fines was attempted using an upflow column. The clay was

never effectively removed from the fines, and the samples were therefore not

further analyzed.

Additionally, a subsample of the Bulk 123 was fractionated by density using

heavy media separation in order to analyze the contaminant differences between

mineral and organic sediment material. In this procedure, the sediment was

combined with a solution of sodium polytungstate at a specific gravity of 2.0.

The mixture was briefly sonicated and then centrifuged to separate the density

fractions. The material heavier than 2.0 specific gravity (mineral) sank to the

bottom, and the lighter fraction (organic) floated on top of the solution and was

Chapter 2 Project Description