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7
Groundwater pollution remediation

and protection

7.1 Introduction 7.2 Groundwater pollution remediation
techniques
Compared with the consequences of groundwater
contamination described in Chapter 6, it is without The remediation of groundwater can involve an
doubt better to prevent pollution from occurring in attempt at the total clean-up of a contaminated aqui-
the first instance in order to avoid expensive aquifer fer or the containment of a groundwater pollution
remediation costs, damage to the environment and source. In certain circumstances, for example in
the necessity of finding alternative water supplies. areas of low risk of human or environmental expos-
In other words, prevention is better than cure. ure to contaminants, a further option may be to leave
Strategies for preventing groundwater pollution are the aquifer to recover through natural attenuation
typically divided between protecting individual processes.
groundwater sources and the wider aquifer resource. The successful remediation of contaminated
Differences are also apparent in dealing with point groundwater must address both the source of pol-
sources of contamination, for example from waste lution and remediation of the contaminant plume.
disposal sites, and diffuse sources such as agrochem- Conventional remediation techniques employ pump-
icals. Groundwater contamination is a global prob- and-treat methods, but these have been shown to
lem and it should also be recognized that strategies be less successful, particularly with respect to the
developed in the more technologically advanced clean-up of pools of trapped organic pollutants such
industrialized countries will need adapting for appli- as crude oil and chlorinated solvents that act as long-
cation in developing countries. term sources of groundwater contamination. Newer
The following sections of this chapter address the technologies include soil vapour extraction, air sparg-
above issues and discuss groundwater remediation ing and bioremediation for the enhanced removal
techniques, risk assessment methods for deciding of organic pollutants. A useful overview is provided
remedial measures and the location of potentially by Fetter (1999). Of increasing interest are passive
polluting activities, and methods for protecting ground- techniques such as permeable reactive barriers
water sources and aquifer resources (groundwater that provide an innovative, cost-effective and low-
bodies). The last section presents examples of how maintenance solution to the clean-up of contamin-
spatial planning, including fundamental changes in ated land and groundwater.
land use, can be used to protect groundwater from The following sections provide an introduction
long-term contamination from diffuse agricultural to the pump-and-treat and passive techniques of
contaminants. groundwater remediation and also review the case
for monitored natural attenuation. The final choice
of remediation technique for a given pollution
incident will be decided on the basis of a thorough
site investigation giving consideration to the type