Strategies for Sustainable Remediation Projects
So far, this book has addressed how sites become contaminated, chemical and physical aspects of contaminant movement, site investigations, risk, vadose zone remediation, groundwater remediation, off-gas treatment, and site monitoring and operation and maintenance (O&M). In this chapter, we cover some strategies for combining remediation techniques to address multiple remediation goals, plus considerations regarding cost, environmental justice, and sustainability. Therefore, this chapter provides an additional environmental, social, and economic context to the materials covered in the previous chapters.
A feasibility study (FS) is a first step towards formulating a cleanup strategy for a contaminated site. The FS, also briefly described in Section 3.3.2, follows the remedial investigation (RI) process and development of the site conceptual model (SCM) described in Chapter 4. These combined processes are often referred to as the RI/ FS process. To perform an FS, an engineer has to already know the various remediation techniques available to potentially remediate the site. Chapters 5, 6, and 7 covered those remediation techniques. This section describes in more detail how to follow the CERCLA FS process once the RI has been performed, an SCM has been developed, and potential remediation techniques are known (U.S. EPA 1988). An FS considers human health and the environment as a priority, as shown in Figure 9.1 (U.S. EPA 1990).
The FS consists of a detailed analysis of remedial alternatives. The feasibility study starts with a screening process, where many remedial technologies are assessed for adequacy for the site conditions. Sometimes the screening process starts while the RI is still in process. As the RI is refined, so is the screening of possible technologies.
After the SCM is more and more refined, and several technologies have been established as adequate for the site conditions, then it is time for a more detailed analysis of remedial alternatives. Remedial alternatives consist of a combination of technologies and management practices that fulfill the criteria shown in Figure 9.1.
The balancing, or technical, criteria are those that technical and engineering staff mostly work on. Some work items for those criteria are listed below (U.S. EPA 1990).
FIGURE 9.1 Criteria for detailed analysis of remedial alternatives.
Long-term effectiveness and permanence
- • Does the remedial alternative reduce residual risk?
- • Does the remedial alternative adequately and reliably control COCs?
Reduction of toxicity, mobility, or volume through treatment
- • Does the remedial alternative treat COCs?
- • Does the remedial alternative reduce the mass of COCs by destroying or treating them?
- • By how much will the remedial alternative reduce the concentrations/ masses of COCs?
- • Is the treatment provided by the remedial alternative irreversible?
- • What types and quantities or residuals remain from using the remedial alternative?
- • Is the community protected during remediation?
- • Are workers protected during remediation?
- • Are there environmental impacts from the remediation?
- • How long will it take for the remedial alternative to meet the objectives?
- • Is the technology able to be constructed and operated?
- • How reliable is the technology?
- • How easy would it be to undertake additional remedial alternatives?
- • Can the effectiveness of the remedial alternative be monitored effectively?
- • Will agencies approve the remedial alternative?
- • Are services and materials available to build and operate the remedial alternative?
- • What is the expected capital cost of the remedial alternative?
- • What is the expected operation and maintenance cost of the remedial alternative?
- • What is the net present worth of the remedial alternative?
These FS criteria have been in effect since the 1980s and continue to help environmental professionals, government environmental agencies, and communities strat- egize how to best remediate a site. With these criteria in mind, the next section describes how to select remedial alternatives.