An analytical result for TPH above 10 ppm only indicates that there are compounds detected by laboratory equipment in the range of TPH. There are, in fact, many naturally occurring compounds that can be detected within these ranges. Man-made products like asphalt from pavement and roof shingles can also be detected within the range of TPH-DRO.
The bottom line is that a positive result for TPH does not necessarily mean you have petroleum contamination. Considering the tremendous financial burden of having to potentially transport and dispose of petroleum contaminated soil, be sure to first seek a professional to collect and closely evaluate representative soil samples and raw laboratory data. A second (and qualified) opinion of a seasoned environmental professional might save your project’s budget significant money.