Use Of Risk Analysis In Environmental Assessment | Environmental Engineering

 Use Of Risk Analysis In Environmental Assessment

The rationale for including risk analysis in environmental impact assessment is threefold:

·         Risk analysis provides a method for comparing low-probability, high consequence impacts with high-probability, low-consequence impacts.

·         Risk analysis allows assessment of future uncertain impacts, and incorporates uncertainty into the assessment.

·         The United States and international agencies concerned with regulating environmental impact are adopting risk-based standards in place of consequence-based standards.

The following example incorporates risk analysis into environmental impact assessment: In 1985, the U.S. EPA promulgated a regulation for radioactive waste disposal which allowed a 10% probability of a small release of radioactive material, and a 0.1 % probability of release of ten times that amount (USEPA 1985). This standard is shown in the stair-step of the diagram of below Fig.. 

           Release of radioactive materials vs. probability of release.

The curved lines are complementary cumulative distribution functions and represent the risks of releases for three different alternatives being assessed. This is a typical representation of the probability of release of material from a hazardous or radioactive waste landfill. The alternatives might be three different sites, three different surface topographies, or three different engineered barriers to release. In the case of the EPA standard, the curves represented three different geological formations. Risk analysis is particularly useful in assessing future or projected impacts and impacts of unlikely (low-probability) events, like transportation accidents that affect cargo, or earthquakes and other natural disasters.

Recently much has been written about the difficulty of communicating risk to a large public, and the perception of risk as it differs from assessed risk (see, for example, Slovic 1985; Weiner 1994). The engineer must remember that risk assessment, when used in environmental impact assessment, is independent of risk as perceived by, or presented to, the public. He or she should assay risk as quantitatively as possible.

Socioeconomic Impact Assessment

Historically, the President’s Council on Environmental Quality has been responsible for overseeing the preparation of environmental assessments, and CEQ regulations have listed what should be included in all environmental assessments developed by federal agencies. For the proposed projects discussed earlier in this chapter the primary issues are public health dangers and environmental degradation. Under original NEPA and CEQ regulations, both issues must be addressed whenever alternatives are developed and compared.

Federal courts have ruled (cf. for example, State of Nevada vs. Herrington, 1987) that consideration of public health and environmental protection alone are not sufficient grounds on which to evaluate a range of alternative programs. Socioeconomic considerations such as population increases, need for public services like schools, and increased or decreased job availability are also included under NEPA considerations. Very recently (O’Leary 1995), federal agencies have also mandated inclusion of environmental justice considerations in environmental impact assessments. Frequently, public acceptability is also a necessary input to an evaluation process. Although an alternative may protect public health and minimize environmental degradation, it may not be generally acceptable. Factors that influence public acceptability of a given alternative are generally discussed in terms of economics and broad social concerns. Economics includes the costs of an alternative, including the state, regional, local, and private components; the resulting impacts on user charges and prices; and the ability to finance capital expenditures. Social concerns include public preferences in siting (e.g., no local landfills in wealthy neighbourhoods) and public rejection of a particular disposal method (e.g., incineration of municipal solid waste rejected on “general principle”). Moreover, as budgets become tighter, the cost/benefit ratio of mitigating a particular impact is increasing in importance. Consequently, each alternative that is developed to address the issues of public health and environmental protection must also be analysed in the context of rigid economic analyses and broad social concerns.

Ethical Considerations

A properly done environmental impact assessment is independent of any ethical system and is value-free. However, ethical questions can arise in formulating a record of decision based on an environmental assessment. Some of these questions are:

Is it ethical to limit resource extraction, with its concomitant environmental damage, by raising the resource price and thereby limiting its use to those who can afford it?

Is it ethical to eliminate jobs in an area in order to protect the environment for a future generation?

Conversely, is it ethical to use up a resource so that future generations do not have it at all?

Given limited financial resources, is it ethical to spend millions mitigating a high-consequence impact that is extremely unlikely to occur (a low-probability, high-consequence event)?

Is it ethical to destroy a watershed by providing logging jobs for 50 years? Conversely, is it ethical to close down a lumber mill, eliminating jobs for an entire small community, in order to save an old-growth forest?

The engineer should remember that none of these considerations are part of environmental assessment, nor are they addressed by NEPA. Addressing them may be part of a record of decision, and is the responsibility of the decision makers.

Conclusion

Engineers are required to develop, analyse, and compare a range of solutions to any given environmental pollution problem. This range of alternatives must be viewed in terms of their respective environmental impacts and economic assessments. A nagging question exists throughout any such viewing: Can individuals really measure, in the strict “scientific” sense, degradation of the environment? For example, can we place a value on an unspoiled wilderness area? Unfortunately, qualitative judgments are required to assess many impacts of any project.