Delineation of a landfill leachate plume and flow channels in coastal sands near Christchurch, New Zealand, using a shallow electromagnetic survey method
Dc. Nobes et al., Delineation of a landfill leachate plume and flow channels in coastal sands near Christchurch, New Zealand, using a shallow electromagnetic survey method, HYDROGEOL J, 8(3), 2000, pp. 328-336
The Burwood landfill, which serves the city of Christchurch, New Zealand, i
s situated on coastal sands underlain by a sequence of aquifers and aquitar
ds. Groundwater flow is toward the coast, located approximately 700m from t
he landfill boundary. Shortly after completion of the first phase of the la
ndfill, an array of wells was installed to detect any contaminant from the
landfill. Leachate was detected in the wells closest to the landfill. A sha
llow electromagnetic (EM31) survey was carried out between the landfill and
the coast, in order to delineate any leachate plume that may be present. O
n the basis of the geophysical results, a contaminant plume and buried chan
nels connected to the coast were identified. Leachate flow initially occurs
in what is probably a channel or pair of channels. Downgradient, the plume
spreads out to the north and south as it moves eastward toward the coast.
Using the geophysical results as a guide, a new set of wells was installed
to confirm the presence of high leachate concentrations. Porewater sampling
confirms the presence of a leachate plume.