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2.10.7 Optimisation of the remediation and long term stewardship process

In future all kind of public and private organisations will continue to spend a lot of financial means on the characterisation and assessment of contaminated environmental media and on the selection, construction, operation, maintenance, and monitoring of environmental remediation systems [ITRC-2004c]. As the various environmental clean-up statutes and their implementing regulations evolved, the initial assumption was that these programmes could follow a basic “study, design, build” linear paradigm. However, years of experience has led to the realisation that the significant uncertainty inherent in environmental clean-up requires more flexible, iterative approaches that manage uncertainty. Uncertainty, as demonstrated by frequently missed target dates, has forced the development of mechanisms that allow for both the systematic re-evaluation of initial objectives and the continuous improvement and optimisation of remediation technologies and techniques. These mechanisms and re-evaluations are known collectively, or generally, as “remediation process optimisation” (RPO). With schedules for projects in the operating and maintenance or long term remedial action phase frequently being measured not merely in years, but in decades, remediation process optimisation is not a just option, but a necessity.

Figure 2.14 Effort versus time in typical remediation actions
Figure 2.14 Effort versus time in typical remediation actions
Figure 2.15 Effort versus time in remediation actions with remediation process
Figure 2.15 Effort versus time in remediation actions with remediation process

In the initial stages of a remediation action, much of the effort is on characterisation and source remediation; limited effort is spent on monitoring. As the project matures, most of the resources are spent for monitoring and operations and maintenance. Figure 2.14 depicts effort and cost versus time for a typical conventional remediation action at a contaminated site. As shown by the dashed line, at most sites it cannot be assured how long it will take to reach closure.

A remediation process optimisation review is a way to evaluate the status of the remediation process and get an idea of when to expect closure. Instead of continuing with a long term operations and maintenance period, the cost as well as the time to completion can actually be reduced through the process of optimisation, as shown in Figure 2.15.

Depending on site-specific conditions, such a remediation process optimisation review could result in substantial savings.

The primary goal of remediation process optimisation should be to ensure that the remediation process is progressing toward site clean-up objectives that are both acceptable and feasible and that selected remediation approaches attain those objectives and remain protective of human health and the environment. Taking account of the general regulatory and technical framework for evaluating remediation processes, regardless of the type or complexity of the remedy, remediation process optimisation should not just look at the “how” of remediation, such as the technologies in place, but also at the “why,” which may be described as the conceptual site model that considers all factors involved with the site remediation, such as the environmental and (current and future) land-use plans, site-specific chemical and geologic conditions, and the regulatory environment.

The regulatory environment establishes the need to review and possibly revise clean-up goals to ensure their continuous applicability. As a result, scientific advances and regulatory changes, such as the movement towards risk-based goals and re-evaluation of technologies deployed, are core features of a comprehensive remediation process optimisation review. Therefore, consideration should be given to the re-evaluation of remediation goals and ways that potentially inapplicable or unattainable goals can be updated based on these and other new regulatory approaches.