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Why GPR Tank Sweeps are so important.

Sep 1, 2020 8:15:00 AM / by David C Sulock posted in OIl Tank Sweeps, tank scans, oil tank leak, foam filling oil tank, pa tank removal

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Protecting your interest when you buy a property is called Due Diligence and one of the most important due diligence steps you can take is performing a tank sweep with GPR. 

Why perform a tank sweep?

Most homes built before 1980 likely had oil heat at one time, so 90% of single family homes likely had oil heat in the past, possible several owners before.  Oil tank are made of metal, they rust, they leak and it can costs thousands if not tens of thousands of dollars to cleanup.  You don't want to buy a home that has an oil tank liability.

 

The home in this photo series is  circa 1920's, so oil usage was 100%. 

Buyers were told the basement had two ASTs (Aboveground Storage Tanks), that were removed. This photo shows where the ASTs were located in the basement.

 

Houses with AST's may also have had UST's

But just because a property had an AST doesn't mean the site didn't have a UST (underground storage tank). 

So why bother to do a tank sweep for a property where there is documentation of former Aboveground Storage Tanks?  Simple nothing lasts forever and the older the property, the more likely that a tank may have had to be replaced.

Can you see evidence of a UST in this photo?   

It's obvious to the trained eye.

All photos on this page are from the same property.     The buyers were told the home had oil heat, the oil tank was an Aboveground Tank in the basement, which was true but seller's failed to mention that the AST replaced an Underground Storage Tank (UST).  Or the owners didn't know that there was a UST since they didn't do a tank sweep when they bought the house.   Although the sellers had their own consultant use a metal detector to scan the site, which couldn't locate a UST.

Tank sweeps experts

 

Simple is not always best.  No doubt your current smart phone ( phone, camera, computer, GPS, etc.) in your pocket is a vast improving from your phone of 10 years ago.  Most likely more expensive but it does so much more.

Having the best available technology also translate to an effective tank sweep.   A $225.00 tank sweep with an $800 metal detector, it not an effective tool for locating tanks, as the cost of the equipment can attest.

metal detectors are poor toold for finding tanks

The sellers metal detector results?

The metal detector produced some deflection around the plant bed indicating a possible metal tank.    Curren scanned the area with GPR and fund the metal signature were the oil tank lines from the house to the tank. 

The metal detector then went over the adjacent driveway.  The findings?

The metal detector indicated a slight, faint response at a location about mid-way beneath the driveway directly in line with the remote fill. Due to the faint nature of the signal, possibly caused by wire or rebar in the concrete driveway pad, the location could not be defined.

 

When you need work performed you want to hire a professional with years of experience and the best possible tools for the job.  Curren was hired by the buyers to perform a GPR tank sweep.

Within the first 10 minutes of the Curren technician being on site, we were able to locate the remote oil tank fill which had been covered over with soil.   See photo below, the red tile probe is pointing to a round cap in the landscaping which is the tank fill.

IMG_6083

Tank Sweep Questions?

IMG_6082-1

If you were buying a commercial property you would perform a tank sweep with GPR as that is the standard and most effective approach.  But if you are buying a commercial property you are more experienced than the run of the mill buyer.

Curren scanned the driveway with GPR and located the tank, which the metal detector could not pinpoint.buried oil tank GPR image

The tank is outlined in yellow lines in the photo below.  The tank was under reinforced (steel) concrete making the metal detector useless, but allowing the Ground Penetrating Radar to locate the tank.

 

GPR Tank Sweep

The best service directly correlates to most experienced and using the best equipment.  Hiring chuck in a truck with an $800 metal detector, who also works out of their house, may offer an attractive price, but are you getting the best service?  Is the metal detector really the best device?

To be fair performing a Geophysical evaluation which is what a tank sweep is, can involve using multiple technologies.   When we find a buried anomaly (tank) we typically also verify the anomaly as metallic using two different metal detectors.  Trust me when you find a tank that a seller didn't know exists, they want to know its a tank, confirming a metallic signature helps the medicine go down, it is just a metal detector should not be your only technology you rely upon.

 

Ground Penetrating Radar tank sweeps

We also have removed thousands of tanks so we know what we are looking for.Tank sweep experts for over 20 years

 

tank experts

locating buried tanks

 

professional tank sweep

 

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Foam Filling Underground Storage Tanks

Jul 13, 2020 8:30:00 AM / by David C Sulock posted in tank foam, foam filling oil tank, foam tank filling

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Utilizing foam to fill an Underground Storage Tank (UST) can be a cost effective approach to closing a UST.   Injecting foam into a tank can save the cost of excavating the entire tank.  Larger tanks and tanks that have access issues & hard surface coverings such as asphalt, building, paving or structures tend to be the ideal sites for foam filling.

foam tank filling

IMG-3794

foam tank filling

 

Is foam filling appropriate and cost effective for every tank?

Short answer is it’s not cost effective in every situation.  People think you can just stick a hose into the tank and pump foam, but that's not the case. The tank must be exposed, entered and cleaned of all oil before foam can be injected. Also, residual oil in the tank breaks down the foam, so the tank must be thorough cleaned of oil or else you will have an issue making proper foam.  In short, you have to enter and clean the tank and for small tanks, it might take that much more effort to remove the tank, since you already excavated part of the tank to enter and clean it.

 

oil tank foam filling

No matter if you foam fill a tank, fill a tank in with sand/slurry or remove the tank there are still a set of tasks and associated costs that will be incurred, no matter the approach.

First, permits are required so the work can be inspected by the local municipality.

Second, the tank has to be excavated to some extent so the tank can be opened, entered and cleaned. You see, you have to clean the tank of all liquid prior to filling it or removing it. Cleaning entails going inside the tank. Now depending on the size of the tank, the physical act of exposing the top of the tank may actually entail exposing 60% to 80% of the tank, which at this point, it may just be another 10 to 15 minutes to uncover the rest of the tank, making removal not that much effort.
OIl tank under a porch

Third, once the tank is cleaned you need to test the soil, which entails cutting holes in the bottom of the tank. This actually takes longer than someone would expect as the person who cleaned the tank, has to leave the tank, change work clothing to cut these holes. Where as in the situation when you remove the tank it is much easier to sample the excavation as the soil is exposed.
soil sampling below a tank

Finally, you have the task of backing the area. If you remove the tank, backfilling is fairly straight forward as you have an open area to fill in.

backfilling an oil tank

If you are leaving the tank in place, you are tasked with placing material in the access hole you cut in the tank and pushing it to the far end of the tank. Remember the tank is a cylinder and you need to fill the cylinder completely, and sand is not self-leveling.

1-888-301-1050

Utilizing foam is convenient as it is self-leveling, but you also have to make the foam on site.

Mixing Truck-2

 

The prep for making foam can be 1.5 to 2 hours. It’s kind of like baking you need the ingredients, proper mixture and temperature). You also have about 2 hours to clean the foam trailer post filling, as the equipment and lines have to be devoid of the foam ingredients or else they will harden and clog hoses, fitting valves, etc. so you are cleaning the kitchen so to speak. Foam filling hits a sweet spot when you have hard issues for accessing the tank with other material such as sand or concrete. Also, larger tanks (tanks greater than 2000 gallons) are more cost effective to foam fill, as you realize the advantages of the foam cost structure verse the labor of using sand or slurry.

Propane tanks are uniquely suited for foam filling as they are pressure vessels and longer than the same size oil tank.  Longer tanks disturb a larger footprint to remove, so foam filling is an ideal solution for propane tanks.

Foam Filling the Propane Tank-2

 

 

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