exception of total xylenes, volatile organic con-

tar samples (Table 4). Because of the variability,

centrations were higher in treated than in un-

there is no statistically significant difference in the

treated samples. Elevated levels of ketones may

samples before and after treatment. Conversely,

be the result of in-situ oxidation of corresponding

when the TCLP results are examined, there is a

alcohols present, but not analyzed for, in the

slight increase in the total leachable TPH in the

starting material.

samples after treatment (Table 5). Here again, the

Increasing  organic  concentrations  runs

increase in leachability is believed to be due to the

counter to the basic principle of the DCR process

increase in surface area associated with the finely

that is designed to encapsulate organics render-

dispersed DCR product compared to the hard

ing them less available. We believe that this out-

and almost intractable obsidian-like tar lumps in

come was caused by two factors. One, the mixing

the starting material. This leachability would be

process broke up the tar masses greatly increas-

significantly lower in hard compacted DCR soil

ing contact surface areas for the extracting solu-

bodies, as in subgrade for parking areas or road

tions. Two, the hydrophobic CaO never properly

construction, compared to the loose, fine product

dispersed into the asphalt tar because at the pre-

subjected to TCLP testing in the laboratory.

vailing field temperatures (< 0C), the asphalt tar

In contrast to the solid asphalt tar, the other

was a solid. The heat of mixing was insufficient