I used to work at ADEQ and spent a lot of time sampling - As BigBen stated there are some issues with the sampling processes. Sherry is just a lab, they run whatever samples that are brought/shipped to them. I noticed all are soil samples from either ditch by Subway or from the residential area, the last several pages "Tentative Results" are estimated values, concentrations are below what the lab can guarantee as accurate. Based on levels I saw - the ditches are pretty clean - roadside ditches usually pick up a lot of compounds from vehicle exhaust. If you want to see the recognized standards go to RCRA Human Health Medium Specific Screening Levels | Region 6 | US EPA and you can see what the regulatory levels are. This way I am not "consulting" or pointing fingers - big grin