Remediation Technologies on the EPA web site
GeoRef is the most comprehensive database of geoscience literature.
Pollution Abstracts contains references to journal articles, conference proceedings, and hard-to-find documents on all aspects of pollution.
Compendex from Engineering Village is the most comprehensive engineering database, covering all disciplines. Use the FindIt button to locate the full text of the articles.
Scopus is the most comprehensive multi-disciplinary database of peer-reviewed literature. Also good for citation analysis.