It has been a few weeks since my last post, but it is time I followup on one of my previous posts regarding impacted soil. In that post, I described a situation where an Underground Storage Tank (UST) was encountered and needed to be removed. During the process of removing the tank, we found that the tank had leaked and impacted the soil and potentially the groundwater in the area of the tank excavation. The excavation had to be back-filled to allow other construction activities at the property to continue, so we removed as much stained soil as we could and back-filled the excavation with a one sack slurry. We also transported the impacted soil offsite and had it properly disposed of.
Now, it’s time to get on with the investigation of the tank leak. Let’s assume that the depth to groundwater in this area is relatively shallow (<30′). Let’s also assume that the soils in the area are sandy or fine-grained (not cobbles or boulders). With these assumptions, we will be able to perform our investigation using a direct-push rig. This device is a truck mounted device that uses the weight of the truck and a hydraulic hammer to drive rods into the sub-surface allowing the operator to collect soil, soil gas, and groundwater samples.
We will collect a few soil samples, soil gas samples, and groundwater samples around the tank area, but there is a significant amount of setup work that needs to be done first. I’ll get into that in my next blog post.