Fig. 5 shows the leachable Zn concentrations. All 138 leachable concentrations were less
than 100 mg/l; the top layer (51 samples) mean Zn concentrations were reduced to 36.6
from 925 mg/l (96% reduction). The mean Zn concentrations for the middle and the bottom
layer samples were less than 4 mg/l (>97% reduction).