Contaminated land may present a significant risk to controlled waters (groundwater,
surface
water bodies or public supply reservoirs). Groundwater risk assessments can range from a
simple comparison of groundwater concentrations against appropriate screening values,
through medium to long term on and off-site groundwater monitoring and complex computer
based modelling to predict the fate and transport of contaminants as they migrate from
their
source.
If the conceptual site model (CSM) has identified that a controlled water receptor is
considered to be at potential risk from contamination, initial assessments such as
groundwater sampling and testing should be undertaken to assess any direct impact from
the
subject site of concern.
Phase 1 – Desk study and site reconnaissance
A preliminary risk assessment is required in order to obtain a good understanding of the
sites history, setting and potential to be affected by contamination. The risk
assessment
comprises desk study research, a field reconnaissance survey and the development of a
conceptual site model.
Phase 2 – Intrusive investigation
If the desk study indicates that there is a potential for contamination, an intrusive
site
investigation and refined risk assessment will be required. The purpose of the
investigation
is to determine whether there are any unacceptable risks to people, property or the
environment.
Phase 3 – Remediation
If the intrusive investigation identifies any unacceptable risks, then remediation will
be
required. Remediation involves the clean-up of a site to ensure that it is safe and
suitable
for use. Remediation may include excavating the contamination or installing clean cover.
Phase 4 – Verification
Verification (or validation) works are undertaken following remediation. The purpose is
to
confirm the success of the remediation works
