SOIL SAMPLING (Please Call to Schedule 503-236-3796)

Soil sampling is the method used to determine if the tank has leaked and is the first step in the certification process.  Two samples are taken within 6 inches of the center of each end of the tank, at a depth range of 0"-24" below the bottom of the the tank.  This is done with either a Hand Auger or a Direct Push Core Sampler (see Photos). 

If one or more of the sample locations is under concrete, then a 2 1/2 inch hole must be bored out at that location to allow access for the sampling tool.  After the sampling is finished, the concrete bore holes are filled with mortar and tooled flush with the concrete.  Most samples can be qualitatively tested in the field at the time of sampling for the presence of petroleum contamination.  Samples are handled in an approved manner that avoids possibility of cross-contamination and are refrigerated immediately. 

Samples are then delivered to an accredited independent analytic testing facility.  Quantitative lab results are usually available within 24 hours.  Contamination levels are initially measured in parts per million (ppm) of diesel and heavy oil.  If contamination levels are greater than 2,500 ppm, then additional lab analysis must be performed called a BTEX or BTEX-PAH  (Benzene Toluene Ethylene Xylenes Polycyclic Aromatic Hydrocarbons.)  These results help determine what level of remedial action, or clean-up, is required to close and certify the site.

The following table show key concentration levels that determine the requirements for site closure.