This document reports on the fourth meeting of the Pilot Study on Prevention and Remediation Issues in Selected Industrial Sectors. The purpose of the pilot study is to define and explore best practices for reducing the health and environmental impact on soil and groundwater from industrial sectors of interest (e.g. metals mining, organic chemical production, gasworks, and fertilizer manufacturing) as well as other unique site types (e.g. old landfills, privatization sites, i.e. facilities transitioning from former state ownership in certain categories), mega-sites, (i.e. large scale former industrial and mining facilities, and shoreline sediment sites). The pilot study will explore the techniques and technologies for preventing and avoiding discharge to soil and groundwater as well as measurement and remediation for that industry sector or site type. It seeks to engage industry and other private sector organizations at the transnational level in sharing and evaluating technical information. In reviewing case studies as well as experience from the previous CCMS pilot study on contaminated land and other sources, the proposed pilot study may be able to assess or benchmark 'what is easy to clean,' 'what is difficult to clean,' and 'what is impossible, at reasonable cost, to clean.' The unique contribution of the pilot study would be measured by its ability to synthesize information regarding best practices, successes and failures, and uncertainties for the sectors of interest. The fourth meeting of the Pilot Study was held in Athens, Greece from June 5-9, 2006. This meeting dealt with the issues small (contaminated) sites in urban areas. Twenty-one technical papers fell under the broad topics of small sites with petroleum hydrocarbon contamination, small sites with other organics, risk assessment at small sites, and sites in unique settings (i.e. residential or congested urban areas). Six countries gave Tour de Table presentations-summaries of the state of the development of waste and/or contaminated land programs in their respective countries. The United States is the lead country for the Pilot Study, and 20 other countries participated in the meeting. This report is a set of abstracts of the presentations at the meeting.