Paul E. Hardisty

The economics of groundwater remediation and protection.

INTRODUCTION The Case for Rational Environmental Decisions Contaminated Groundwater - A Global Issue Groundwater Contamination, Risk, and Remediation Economic Value of Groundwater - An Introduction APPLYING ECONOMICS TO GROUNDWATER Overview of Economic Analysis Groundwater in an Economic Context Economic Theory for Groundwater Remediation Remedial Costs Remedial Benefits REMEDIAL DECISION MAKING Context Setting an Optimal Remedial Objective Reaching the Objective CASE STUDIES Remediation of a Manufactured Gas Plant Site in the United Kingdom MtBE-Contaminated Aquifer in the United States Tritium-Contaminated Groundwater Example Problem and Solution SUMMARY AND CONCLUSIONS Glossary of Economic Terms Index

Characterization of LNAPL in fractured rock

Behaviour of light non-aqueous phase liquids (LNAPLs) within a fractured rock mass is a function of the properties of the immiscible fluid, the fracture network, rock matrix properties, and the groundwater regime. LNAPL behaves differently in rock with open fractures than it does in porous media. Relatively small volumes of LNAPL within vertical or subvertical fractures can produce significant LNAPLpressure heads, resulting in LNAPL penetration into the saturated zone. Penetration can be significantly deeper than predicted by porous medium models. Groundwater surface fluctuations can cause lateral LNAPL migration, even up-gradient to natural gradients. Characterization of LNAPL-contaminated fractured rock masses must take into account these fundamental differences in behaviour. Site investigation should focus on determination of fracture network and rock matrix properties, understanding of groundwater surface fluctuation dynamics, and consideration of spatial LNAPL distribution. A combination of techniques, many not used in porous medium investigations, but can used to develop a detailed conceptual model. These include coring, angled holes, digital borehole imaging, and fracture casting for aperturedetermination. The data provide information on LNAPL occurrence and behaviour, allow LNAPL spill volume to be estimated, indicate future movement, and ultimately allow for more effective and economic remedial decision making.

The economics of contaminated site remediation: decision making and technology selection

Abstract Most activities associated with production of goods and services in modern society are linked directly or indirectly to the production of wastes and pollution. In general, environmental impacts increase with the level of production (as measured by the Gross National Product, or GNP). The decision to remediate a contaminated site can be seen from the macroeconomic and microeconomic viewpoints. Macroeconomics can be used to plan and account for the overall cost of pollution as part of a firms production, and thus make overall decisions on the real cost of pollution and the level of clean-up that may be called for. Valuation of damaged resources, option values and intrinsic worth is an important part of this process. Once the decision to remediate has been taken, the question becomes how best to remediate. It is safe to say that cost is one of the single most important factors in site clean-up decision making. A basic rule of remediation is often taken to be the maximization of contaminant mass removed for the money spent. However, remediation may also be governed by other objectives and constraints. In some situations, minimization of time, rather than cost, could be the constraint. Evaluation of the economics of a clean-up project is directly linked to the objectives of the site owner, and the constraints within which the remediation is to be performed. Once objectives and constraints have been clearly identified, a range of possible remedial approaches and technologies can be developed, and each option evaluated on a comparative basis. One of the most powerful tools for comparative options analysis is technical-economic analysis. This approach combines evaluation of technical feasibility and effect, with consideration of capital, operation and maintenance costs over a selected time horizon. By constraining remedial alternatives within cost and time boundaries, possible solutions can be evaluated with respect to specific criteria. Two examples illustrate these concepts. Economic analysis of remedial options for containment of a 350 000 1 hydrocarbon spill migrating through fractured rock into a river in Alberta, Canada, provided clear direction to the site owner. Economic analysis of remedial alternatives for contaminated sites in the UK sheds interesting light on the common practice of landfilling, when compared to other alternatives.