The overall recovery of the injected tracer is 4.31%, from which approximately
57% of the tracer was recovered in the B152 well and 43% in the B139 well. In
general, the tracer progressively moved from east to west following the direction of
the groundwater flow within the area of interest. The closer proximity of the B152
well to the application well (B149) is demonstrated by several factors: the first arrival
of the tracer (reaching the B152 well 1 day after the start of the test) and by both the
peak tracer concentration and time to peak tracer concentration (245 mg/L on 9th
day). On the other side, the tracer achieved a peak concentration of 64 mg/L on the
13th day after the start of the tracer test, first arrival of the tracer into B139 was
Fig. 6.4 Isolines of tracer concentrations at day 6
Fig. 6.5 Isolines of tracer concentrations at day 13
6 Field Study II: Pilot Application of nZVI/DC-Combined Methods at Aargau Site
109