The main decision-making tool when selecting a groundwater remediation technique is an economic evaluation of all viable techniques. During the planning stage of any kind of remediation scheme the costs and effectiveness of the different techniques have to be compared. It is very important that long-term remediation costs are factored into these comparisons, although these are difficult to estimate. In general, the costs of remedial activities are classified as capital investment costs which stem from the construction of the remediation system and operation and maintenance costs which arise continuously or periodically during operation of the system.. An economic evaluation of a PRB scheme needs to take account of: 1. Expenditure on the site investigation; 2. Costs of preliminary and feasibility studies; 3. Planning and engineering; 4. Construction costs; 5. Costs for reactive materials (including any recovery, replacement and disposal costs); 6. Maintenance; 7. Monitoring (to verify long-term performance and demonstrate remediation success). PRB systems usually have relatively high capital investment costs (planning and construction), whereas operation and maintenance costs are normally much lower than those of most active remediation techniques, although this depends on case-specific factors such as the type of contamination, the hydraulic conditions on site, etc. From both a performance and economic standpoint the long-term performance of a PRB system is a critical area in determining its viability. Before a decision on installing a PRB system can be taken, a reliable prognosis on the probable operational life-time of the system [1,2] has to be made. Indeed, lowering the expected operational and maintenance costs is the main motivation for research and development in the field of PRBs.A number of papers have been published dealing with costs of groundwater remediation by both active (pump-and-treat) and passive (PRB) systems However, the projects differ substantially in size and complexity. In a report of the US EPA the economics of 22 PRB systems were analysed. The volume of groundwater treated was between 1000 and some 400,000 m3 per year. The operating costs and capital costs in US$ per m3 water treated per year were highest for the smaller remediation projects and decreased significantly for large projects. Of course these costs also depend on the site characteristics and the type of contaminant. [3]