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

MONITORING NETWORKS AND METHODS
(Gabriel, 1993). The hole was covered with a standard 13x13 cm stop-cock cover. Many of
the holes are no longer accessible but at least 30 remained open during the course of the
project.
The second set of piezometers was drilled during summer 2000 as part of the Environment
Agency River Tame Asset Survey. The holes (ID 150 mm) were drilled to depths of up to
10.5m by light percussion rigs within 15 metres of the riverbank. Completion was similar to
that employed in the Severn Trent holes with the response zones ranging from 1 to 3 metres in
width (Caudell, 2000).
A total of 20 shallow piezometers were sampled representing ten point samples adjacent to
the river and ten across the northern side of the Tame Valley up to 2 km from the river.
In Sutton Park, four shallow piezometers were sampled (Figure 4.3). These formed part of a
network installed by South Staffordshire Water Company to monitor the effect of a nearby
public supply well.
4.5.2.1 Sampling methods
A low-flow Waterra pump was used with HDPE tubing (ID 10mm, OD 13mm) and stainless
steel ball valves. Dedicated tubing was used for each hole and left in place between sampling.
A total of three ball valves were used and rotated between each site, those not in use were
soaked in distilled water. If possible, three well volumes (inclusive of the gravel pack) were
purged prior to sampling but this was not always possible owing to the slow recovery time of
some piezometers. In each case a note was made of the purged volumes. Samples for
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