45

where CP0 = initial concentration of the parent compound, and Rp is the
retardation factor for the parent compound. For the daughter compound, the
model is:
Cd -q1]-exp     RP                  (3.16)
where Rd is the retardation factor for the daughter compound.
3.4.3 Heavy Metals
Degradation tests for Zn followed the procedure described in the Sec.
3.4.1.1. The chemical analyses and the data evaluation were also conducted
following the methods in the Sec. 3.4.1.
3.5 COLUMN TESTS
Column tests were conducted to determine transport parameters (i.e.,
partition coefficients, rate constants, and dispersion coefficients) under more
realistic conditions for foundry sands, iron, and mixtures of foundry sand and
iron. Two types of tests were conducted with TCE solutions: constant hydraulic
gradient tests and constant flow rate tests. Only constant flow rate tests were
used for solutions containing alachlor, metolachlor, and zinc.
3.5.1 Experimental Set-up
Schematics of the column test set ups are shown in Fig. 3.7 (constant
head test) and 3.8 (constant flow rate test). The reactive medium was tamped