Case Studies: Full-Scale Operations and Delivery Systems - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 349

TABLE 13.2
Representative Characteristics of the Site for Case Study #2

Concentration at Nominal
Subsurface Depth (m)

Characteristic 0 - 0.6 1.8 - 2.4 4.8 - 5.4

Particle size distribution:
Clay: < 0.002 mm, wt%
Silt: 0.002 - 0.05 mm, wt%
Sand: 0.05 - 2.0 mm, wt%

-
-
-

22 - 25
65 - 67
8 - 12

12 - 15
39 - 64
22 - 46

Water content, dry wt% 16 - 23 17 - 19 22 - 24

pH - 5.3 - 6.0 6.2 - 7.4

Total organic carbon, mg/kg - 600 -1200 200 - 500

Total VOCs a , μg/kg 9900 5300 1500

Chromium, mg/kg - 13 - 31 9 - 20

Lead, mg/kg - 20 - 28 16 - 23

Nickel, mg/kg - 8 - 18 7 - 20

Total alpha, nCi/kg (10) ND b - 150 ND ND

Total beta, nCi/kg (10) ND - 200 ND - 31 ND - 33

Total uranium, nCi/kg 2 - 250 1 - 3 2 - 3

Technetium, nCi/kg (2) ND - 380 - -

a Total VOCs = summation of trichloroethylene, methylene chloride, 1,1,1-trichloro-
ethane, 1,2-dichloroethylene, and 1,1-dichloroethane.
b Not detected at limit shown in parentheses in first column.

13.4.2.2 Treatability Studies

Three soil samples containing low, medium, and high concentrations of VOCs (TCE,
1,1,1-trichloroethane, methylene chloride, 1,1-dichloroethylene, 1,2-dichloroethyl-
ene, 1,1-dichloroethane, 1,2-dichloroethane, vinyl chloride, chloroform, carbon tet-
rachloride) were tested. The criteria for successful treatment were concentrations in
the TCLP extract of: (1) < 25 μg/l for TCE, and (2) sum of < 86 μg/l for all the
VOCs. Preliminary testing resulted in VOC concentrations below detection limits
for both stabilized and unstabilized samples (see Table 13.3). The TCLP procedure
was modified to a 1:5 dilution instead of the normal 1:20 dilution in an attempt to
avoid concentrations below detection limits because of the low VOC concentrations
in the soil samples.
The performance evaluation studies investigated the performance of portland
cement and a proprietary reagent effective in the solidification of soils contaminated
with VOCs. A control sample was mixed in a manner similar to the core samples, but
without the addition of the admixture or water (portland cement was added to help
the high-clay content soil to break apart). Analyses for total and TCLP VOCs were
performed on untreated and treated core samples. The treated materials were cured
for 3 days, after which a 100-g portion was removed from each jar, size-reduced as
quickly as possible, and a 25-g aliquot transferred to a zero headspace extractor for
TCLP/VOC extraction (EPA SW-846 Method 1311). All volatile organics analyses