Oil tank removal and contamination cleanup.
We were contacted by an environmental engineer overseeing a commercial demolition / rebuild project in Newark, DE. The building lot was very narrow and they found a tank at the property line partially under the footing of the building next door. We advised them we would need to obtain a city license a permit to do the job but they decided not to wait as it was holding up the construction of the new building.
They brought in a different contractor and it was decided to leave the tank in place so they would not disturb the footing above it, they cut it open, cleaned it out and filled it with concrete.
Fast forward a couple of weeks they found another underground oil tank, this one had been cut open (never cleaned out) and just filled with soil. This is something you would never do. We were brought in again at this point because the contractor they used for the first tank, price gouged badly and was not allowed back onto the site.
While we were in the process of obtaining our city license and the permit someone discovered that a major structural point load for the new building was going to be resting directly on top of the tank that had been filled in with concrete and none of the structural engineers were willing to sign off of it. It was then decided that the tank had to be removed from under the footing after all.
After a site visit we discovered that the tank was only under the footing a few inches and it would have been an extremely easy job to remove before it was filled with about 6,000 lbs of solid concrete.
The first day of the job we were able to safely remove the tank filled with concrete out from under the footing, we cut the steel tank off of the concrete and hammered the concrete into small pieces and disposed of them at a concrete recycling facility. We then poured 4,000 psi concrete where the tank had been removed from rather than backfilling with stone to create additional structural stability for the new footing with the point load.
We then cleaned out the tank filled with soil which was contaminated since the tank was not cleaned out, placed the soil onto plastic and backfilled the hole with stone.
Soil samples were taken from the excavation to make sure there was no remaining contamination left as well as samples from the contaminated pile to determine the types of contaminants in the soil, the results were then forwarded to a disposal facility for approval.
Normally a GPR is done prior to purchasing a property to minimize these types of issues after purchase, but in this case there was actually a building on top of both of these tanks and they were found after the building had been demo’d.
Environmental Remediation does not have to be a complicated process but you do need the right team of people on your side that are highly experienced, knowledgeable and expert at what they do. Having the right people always makes a difference.
