115

mixed in equal proportions with silica sand (50% - 50% by weight) to increase the
hydraulic conductivity. The partition coefficient obtained from the column test for
Sand 11 was doubled under the assumption that sorption of TCE on the silica
sand would be negligible.
A summary of the partition coefficients is in Table 5.9. For Sands 1 and
12, the partition coefficients obtained from constant head and constant flow rate
tests are significantly different (Fig. 5.11 and 5.12). Greater partition coefficients
were obtained from the constant flow rate tests. The reason for the discrepancy
between these two tests is unclear.
Partition coefficients from the column tests are graphed against those from
the batch sorption tests in Fig. 5.13. The partition coefficients from both tests are
comparable, but in general the partition coefficients obtained from column tests
are slightly higher than those from the batch tests. Thus, designs based on
results of batch tests should be conservative.
5.3.3 First-Order Rate Constant
Transport parameters obtained from the column tests are summarized in
Table 5.10. The KSA for foundry sands and Peerless iron were calculated using
Eq. 3.18. For Peerless iron, KSA was computed using the steady-state solutions
(Eqs. 3.22 - 3.23). Similar KSA for Peerless iron were obtained using Eqs. 3.22 -
3.23 with and without dispersion, where the dispersion coefficient was estimated