e9dd6711_Soil_sampling__RISK_CONTROL
[SPECIFIC JOB STEPS] A. Tank PitIf there is a question as to the extent of residual contamination, or if comprehensive documentation is necessary, a tank pit may be sampled for laboratory analysis. A total of five samples should be taken from the excavation. One composite sample from each of the side walls at a distance approximately one third up from the bottom of the pit. Several samples should also be collected to form one composite sample from the bottom of the pit. Any remaining samples should be grab samples from areas with greater potential for contamination such as stained soils, adjacent to a corrosion hole, opposite a manway, or opposite a tank opening. [RISK ASSESSMENT] From how deep should the samples be taken? [RISK CONTROL] 
All samples shall be taken no less than 15 centimeters below the exposed surface being sampled. Samples for compositing should be taken from random locations on the floor and walls of the tank pit.
Soil sampling
RISK CONTROL