For an ETS a site visit (interior and exterior) is completed and only one specified type of historical research (although ERAS usually performs additional research). A Phase 1 project includes the same tasks but all available historical sources of information are reviewed. In addition, more detailed geology and hydrogeology is included as is additional description of the site including a site diagram and photographic documentation. Phase 1 projects are usually performed in more developed commercial and industrial areas so they often also include review of file information for nearby leak sites.