The impact of urban groundwater upon surface water - eTheses ...

MONITORING NETWORKS AND METHODS
Samples for VOC analyses were collected from a piece of LDPE tube of length sufficient to
contain the sample volume. This was connected directly to the river bed piezometer. A fresh
section of LDPE tube was used at each sample location to prevent cross contamination. The
VOC sample was collected after all other sampling had been carried out. This was to ensure a
large volume of fluid had passed through the sampling tube to reduce the impact of sorption
when the final VOC sample was taken. To reduce the risk of VOC sample degassing
/volatilisation the sample tube contained a full column of water back to the peristaltic pump
and the sample was taken from the base of this column. Three standing water volumes were
purged prior to the commencement of sampling. It was noted that the piezometers appeared to
be ‘developed’ during pumping with subsequent sampling runs yielding faster discharge rates
owing to the removal of fine sediments adjacent to the piezometer screen.
4.5.2 Shallow monitoring wells
Groundwater quality (and head) data were obtained from two sets of shallow piezometers
(