HRS Guidance Manual, Section 6.5, Subsection D1
D1. Locating Data
The following may provide accounts of the areas of sources containing hazardous substances:
- PRP data
- State data
- Property records
- EPA signed and finalized compliance orders
- Aerial photographs
To calculate the area of the source, all of the following must be true:
- The area of the source (or a portion of the area) can be estimated.
- The source was not assigned a value for volume.
- The hazardous constituent quantity and/or hazardous wastestream quantity were not adequately determined for the source.