KEY CONCLUSION: The possible environmental impact from operations at gasoline stations can always be evaluated regardless of the subsequent history of uses or new building construction.

A large number of gasoline service stations have historically operated in the United States. The largest number of stations may have been present in the 1950s when gasoline hungry cars became more popular and numerous. In addition, there were many smaller independent oil companies that were competing for consumers at that time.

Leaks from gasoline stations may be the most common type of contamination site and costs for cleanup have exceeded $1-2 millions dollars in some cases. Proposed Phase 2 investigations may be complicated if the stations was removed a long time ago because quality records may not be available, may have been lost or not well preserved. The investigation may be further complicated if the property has been redeveloped with new construction.

Regardless of the circumstances and present configuration, it is necessary to evaluate subsurface environmental conditions at these sites.

Based on historical research, maps, plans or drawings may be available indicating the layout of the USTs and pumps. This is a significant argument for conducting a Phase 1 .

The history of use and development will determine the scope and cost of the required Phase 2 investigation. If scaled maps or plans are not available, the only possible method to determine the former station layout is through historical aerial photographs from the year or years the station is known to have been present on the site. Despite what some may believe, Sanborn Maps do not indicate the complete layout of the gasoline stations, only where the buildings were located.

On some properties the layout of the station cannot be determined from historical sources or the appropriate sample locations may be obscured and covered by newer buildings. In this case, the only practical way to assess subsurface environmental conditions is to determine the groundwater flow direction in the area of the Property. This is also often determined through a Phase 1 ESA but with new on-line resources, it may only require only a quick review of nearby leak site groundwater information. Borings can then be drilled down-gradient of the former USTs, pumps and auto repair facilities and groundwater samples collected for appropriate analyses.