Hot Environmental Topics

Why Metal Detector Tank Sweeps Fail?

Oct 6, 2021 11:56:00 AM / by David C Sulock posted in OIl Tank Sweeps, tank sweep, gpr tank sweeps

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Tank sweeps, or tank scans are an evaluation of a property for a buried Underground Storage Tank (UST). Unfortunately, these sweeps/scans have become generic to so many and people are unaware of the limitations, between both the companies providing the scan and the technology used.

Metal Detector              Pat GPR Office-1

                             Metal Detector                                      Vs.                         Ground Penetrating Radar

Best price, means least expensive technology (metal detector), for example would purchase a 5SE phone vs. the IPhone 12? Maybe for your young kids, but not for you. The best  utilized  technology for locating underground oil tanks is Ground Penetrating Radar (GPR).                     

An example of using a metal detector as opposed to a the Ground Penetrator Radar - Curren was provided a report from a client who asked for an underground oil tank removal. Oil tanks were discussed in the report. The tank locatoror who provided the tank scan with noted the following: “While conducting the oil tank scan it was noticed that there is the possible presence of an oil tank at the front of the home. This was noticed using Schonstedt magnetic locator which detects the magnetic field of ferromagnetic objects. The object that was detected is 3ft x 5ft. After detecting this object a 4 ft probe was inserted into the ground in this area and we detected a object about 3 ft below the surface. A qualified oil tank removal company should further evaluate to determine the size and depth of the possible tank. This company should also conduct proper soil samples to determine if a leak is present at the possible tank.” Several photographs were also included to indicate the meter utilized, and the areas investigated. 

Instead of doing another scan with the Ground Penetrating Radar, the client asked Curren to remove the said underground oil tank found with the metal detector. Curren mobilized equipment and labor to remove the #2 fuel oil UST (subject tank). Curren excavated in the area identified in the Tank Inspection report to a depth of 9’.

No tank was located. Curren then excavated toward the residence additionally to 9’. No tank was located. Curren inspected the basement for copper lines and no copper lines were found.

Conclusions & Recommendations

The conclusions are based upon the review of available information, field observations and test results obtained during this project. Curren Environmental, Inc. does not assume any responsibility for using this report for purposes other than those indicated in the specific area investigated.

Based on onsite observations, the areas indicated in the report were investigated, no underground storage tank was located in this area. The client, ended up spending a large sum of money to remove an oil tank that was not there.  

What is a metal detector? "Metal detectors use electromagnetic fields to passively or actively detect the presence of metallic objects. Passive detection measures the changes in the Earth's magnetic field caused by an object."  The photo below shows some debris, that debris was located by a metal detector.  Curren was contracted by client to remove the "underground oil tank".  The metal detector tank sweep found debris, not an oil tank. 

buried metal debris from metal detector tank sweep

What is a ground penetrating radar system? Learn more here.

 

 

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Home Inspection finds a buried oil tank.

Jul 21, 2021 11:03:09 AM / by david sulock posted in OIl Tank Sweeps, tank sweep, gpr tank swep, foam filling oil tank, gpr tank sweeps, gpr tank scan

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What  happens when a home inspection finds a possible underground oil tank?

A common request our office receives regarding a tank sweeps.

"Hello, I'm selling my home and we suspect that the buyer did a tank sweep with a metal detector vs GPR. They supposedly think they found a tank on the property. We do not see any evidence of a tank, nor was one disclosed by the previous owner (who bought the home in the 70s, house is 80 years old). Is it possible that this 'tank' is just a gutter drain pipe, part of our sprinkler system and/or rubble backfill such as a chunk of concrete sidewalk with rebar or metal containing soil? If so, would a GPR scan be conclusive? Thanks."

This is a common situation we get from property owners who are told they have a buried oil tank.   The owner has the question regarding if the meta detector is reliable.    Here are some common talking points...
  1. The property owner is unclear how the suspect tank was found.  Was it found with a Metal detector, or  Ground Penetrating Radar or both? (both GPR and a metal detector would be best) The solution would be having the owner receive a copy of the Tank Sweep Report so they would have a baseline regarding what they found and where. Yes, every professional service should come with a report, no report, then question how professional the service was.
  2. The property is over 70 years old, so while the owner has no knowledge that there was an oil tank, they also have no documentation that there was not an oil tank. A 70 year old property most likely had oil heat at one point in time as oil was very popular in the past and other fuel sources such as natural gas was not commonly available or financially appealing until the 1970's.
  3. The tank scan found a buried object, presumably metal. If only a metal detector was utilized, you can't say 100% if the metal found is a tank as metal detectors detect metal and properties have all sort of buried metal. Metal can be in the soil naturally, you could have buried debris, buried metal pipes or surface metal (like a fence) that distracted the metal detector and have a false buried metallic signature reading. Happens all the time. A metal detector on a sandy beach is great it will find buried metal, likely a bottle cap, but people hope for coins or expensive jewelry. People paying a couple hundred dollars for someone to use an $800 metal detector to find a tank are also helpful.
Call Curren TodayThe photo below was where a metal detector thought there was a tank.  There was no tank, just soils with a metallic signature.

tank home inspection

The guy in shorts, is using a $900.00 metal detector and found a suspect tank in the front yard.

metal detector tank scan

When you scan for a tank, the more expensive the equipment the better.   GPR (Ground Penetrating Radar) costs tens of thousands of dollars because it has the technology to do the job.

best oil tank sweep with gpr

 Effective Oil Tank Scan or Oil Tank Sweeps like on commercial sites would use GPR as it will                            provide a signal (image) of buried objects.

buried oil tank found via GPR

The signal above shows the underground oil tank. 

Purchasers of commercial properties are more aware of the liability associated with leaking USTs (Hundreds of thousands of dollars) compared to a residential home buyers (Homeowners think a few thousand dollars is a lot.) So on the commercial side of real estate tank sweeps are completed with GPR, not metal detectors. Most environmental consultants that perform tanks weeps will use GPR and discount the cost for residential sites. Nobody wants to see someone buy a house and find a $50,0000 cleanup is required.

What if a buyer finds a suspect tank?

This is a really hard question because it relies so much on the quality of the tank sweep.    If they used GPR, if the property is likely to have had an oil tank (older the home, the more likely) and if the buried anomaly has the signature of a tank.  Well then you have to excavate and confirm that object is an oil tank.

Who pays for the oil tank removal?

Owner will pay 98% of the time as finding a hidden oil tank is a defect that needs to be addressed.

Do they have buried oil tanks at the beach (shore)?

If the home wanted heat, then yes homes along the coast and on islands had buried oil tanks.  Oil was king up until the late 1970's in New Jersey.  The photo below is of a home we scanned on a barrier island.  Many older beach houses eventually converted to natural gas, as gas could also  fuel the stove, dryer,  hot water heater etc.   After conversion to gas, it was not uncommon that the tank was just left in the ground.  So short answer beach houses had oil tanks.

Tank sweeps at the beach

What if a suspect tank is found and we don't believe its a tank?

Short answer prove your opinion right and dig it up and verify its not a tank.

What is the best tank sweep?

Using Ground Penetrating Radar is the best technology for finding buried tanks at properties, period.  Can you use a metal detector to verify a GPR signal that identified a tank?  Sure, always verify the object is metal.  GPR can't penetrate metal so when a GPR sweep pings a tank, it means the radar can't penetrate the object (likely a metal tank) but there are buried concrete tanks.  Metal detectors can verify an object is metal, but a metal detector  should not be used to be your sole technology

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Tank Sweep Differences

Jun 1, 2021 10:45:00 AM / by David C Sulock posted in OIl Tank Sweeps

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People are different. Homes are different. Not all cars are the same. 

What about Tank Sweeps?

The generic term, "Tank Sweep" gives you two distinct approaches to perform a sweep and the quality level are polar opposites.

First off, the purpose of having an Oil Tank Sweep done in NJ, PA and DE is to detect for the presence of an intact, underground oil tank. The reason you want to identify an underground tank before you buy a property, is to avoid the potential of paying for a contamination cleanup from a leaking tank. In our world a small clean up is under $15,000, more extensive cleanup start around $75,000 and go into the $100,000's.     You can see why a quality tank sweep is important. 

So when you are faced with tens of thousands of dollars to address a tank leak, go with the best approach which is using GPR (Ground Penetrating Radar) for a tank sweep.  The technology will cost you a few hundred dollars more than someone using a metal detector, but the quality of the two approaches is night and day.  

GPR sends radio waves in the ground which can reflect off of a metallic object giving the technician an image.   Certain images are tanks, some are pipes, some are debris.

IMG_8520

 

There are dozens of people who have bought an $800.00 metal detector and work out of their home and do tank scans.   If only a tank was the only metal on a property, then these people would be super geniuses, but alas, metal is abundant in the ground, naturally in some soils, rocks, pipes, rebar, buried debris, above ground what do you have that doesn't have metal?  The point being you can't use cheap technology for such an important service.

To top it off, these one person bands,  as they don't remove tanks, so if you find a tank, now you have to find a company to remove it,  In a real estate transaction delays are bad.

The icing on the cake is we have been hired to remove tank found by the metal detector sweep person to only dig up not an oil tank. Really, we find no tank about 65% of the time. 

Five Tank Sweep Tips.

1. Ask the selling about prior oil heat.  In NJ they are supposed to disclose it, in PA they are not.  In every state we work the owners have  not been 100% honest with a tank disclosure.   I say this because we do thousands of tank sweep, tens of thousands tank removals so we touch more properties than pretty much any company in the area (we have been do this work for decades.)

How are owners not honest about an oil tank?  Well after we find one, many owners suddenly have tank paperwork or now remember yes there was a tank on the property.  This is 100% accurate statement

So always ask in writing about what they know regarding prior oil usage at the site.  People lie about USTS (Underground Storage Tanks) and ASTs (Aboveground Storage Tanks).   

2.  Look at the neighborhood, are there houses with oil heat?  Bingo do a scan.

3. Don't ignore ASTs (Aboveground Oil Tanks), many AST's replaced USTs.

4. If a property had a tank removed, don't assume that was the only tank.  Do a tanks weep, many sites had 2 tanks.

5. Check with the town regarding any permits for tank replacement, filling or removal.

What if a tank sweep finds an oil tank?

At Curren we provide a cost to remove and test the tank.  Tested clean tanks are not a problem. Many owners will hire us because they need to address the tank they didn't know about and well, we do this a lot, are competitive,  experienced and work in our client's best interest.  If we can save a client money we do, its in our DNA.

That said, don't run away from a property after you find  a tank (the next property may have one), rewove and test it.  Of course if the property owner refuses to address the tanks, well in that case, run away (walking isn't fast enough).

Bottom line when you find a tank, you want it removed and tested, and remediated if it leaks.  It truly doesn't matter to us if we remove the found tank or not.  Hey many property owners are mad we found a tank, true. We just want the tank removed and tested so our client doesn't have to deal with that expense. 

 

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What happens after a tank sweep?

Feb 22, 2021 10:00:00 AM / by David C Sulock posted in OIl Tank Sweeps, tank sweeps with GPR, gpr tank sweeps

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Understand the process of a tank sweeps and what happens after a tank sweep.

The best situation regarding a tank sweep is finding a tank, therefore it can be removed and soil tested to prove that no soil remediation (cleanup) is required. what happens after a tank sweep.

A hidden or an underground oil tank is a major financial liability when buying a home, because rust never sleeps and oil leaks from the tank. Soil remediation from leaking oil tanks can easily cost into the tens of thousands of dollars.   A tank sweep of any property is always recommended unless you can document the site never had oil heat, unfortunately older homes had oil heat since it was the only option after coal use.

Should I buy a house with an underground oil tank?

An underground oil tank can make a home harder to sell or worth less to a potential buyer, how does a $32,000.00 oil tank cleanup ding the value of a home? A known oil tank can also increase the chances of complications with getting to the closing table and the home sold. Mortgage lenders are wary of buried oil tanks and may refuse to lend on a home with an underground tank.

oil tank leaks

What is the life expectancy of an underground oil tank?

The average life of a UST is about 20 years (if you bought a middle of the road tank today, that is your warranty. However, with the tank buried, other factors will influence the lifespan of underground tanks, including the gauge of its steel, geology, corrosivity of the soils, etc. 

FACT:  most tanks were used past their design life expectancy and left in the ground unused past their life expectancy as well.

Photo Mar 13, 10 37 24 AM

How do you manage the liability with an oil tank?

The liability of an oil tank pertains to leaks that occur and the state mandated cleanup of the oil leaks.   The best situation regarding a tank sweep is finding a tank so it can be removed and tested to prove that no cleanup is required.

What happens if the tank sweep does not find a tank but points to a tank being removed?

This is not your best scenario because now you do not know if the tank leaked or where the tank was located. Clearly not finding a tank means your investigative work is not complete, because you do not know if the tank leaked.   Tank sweeps cannot find removed tanks, so you are tasked with historical research on who removed the tank. Bottom line you have to make an effort to find where the tank was located.   Sometimes owners get a conscience  and will admit that a tank was removed, they just did not think that knowledge was relevant at that time. Sometimes a tank sweep can point to a likely area of where the tank was located.

We had a case where an owner removed their own tank in the backyard without a permit.   They eventually were going to sell the home and did not want the tank as an issue. The final cleanup was around $40,000.00. Someone admitting to a bad thing is not common, but we do see it happen.

 tank leak costs

Sometimes we can find the tank grave, other times we have to do a grid of soil borings in the suspected area to try and find the tank grave and to test soil. Testing a removed tank excavtion

Tank sweeps that point to a removed tank will lead to soil testing in the area of the removed tank, unless of course a report exists of the tank removal with testing and a clear statement that the tank did not leak. Best case you find no contamination, worst you find contamination, which is reportable to the state and further work would be necessary.

Be aware there have been many tanks that were removed, that leaked and were not cleaned up. Owner hoped no one will look or test the area.  If you don't have  a report that includes laboratory data saying the tank did not leak, you don't have what you need to remove the liability of the tank.

Need to learn more about tank sweeps? Click here. 

 

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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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Why is an Oil Tank Sweep Important?

Jan 13, 2020 9:43:00 AM / by david sulock posted in OIl Tank Sweeps, underground oil tanks, tank sweep, gpr tank swep

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                    Why is an Oil Tank Sweep Important?

From 1900 to 1945 coal was king (coal shortages were common during WWI). By the mid 1930’s oil burners had made quality and safety improvements that made oil a competitor to coal. In 1940 more than half the homes burned coal. America oil reserves and steel making prowess from WWII allowed oil to be rapidly adopted after WWII (1945).

In the 1970’s and 80’s due to natural gas shortages and price irregularities the natural gas market become deregulated. Deregulated allowed for competition and market based pricing, which meant lower prices, this drove the popularity of natural gas. So natural gas didn’t become popular until the late 1980’s.

For homes built between 1900 and 1980, oil heat was highly probable at some point in the past (in short what were your alternate choices for heat besides oil?). Construction codes didn’t address oil tank removals until the 1990’s. Environmental regulations today have strict standards for heating oil leaks from tanks in soil and groundwater. In short, an oil tank leak can make the owner of a property a polluter so to speak. On top of that the regulations view the current owner of a property as the Responsible Party (RP) for the cleanup.

Today, you could buy a house built in 1950, that used oil until say 1980, when a conversion to gas occurred. The old oil tank was literally just left in place (abandoned), since doing anything cost money. Fast forward to 2020, you are buying that home with an oil tank that hasn’t been used in decades. If you don’t add a tank sweep with GPR (ground penetrating radar) to your home purchase due diligence you are opening your self up to a responsibility and an expense with the oil tank, as when you sell someone will do a tank sweep and find the tank you never knew you had or used, which happens all the time.

Today the internet is used not just for shopping, but for education. There are homeowners that have an oil tank on their property (used or out of service), these homeowners have learned via the internet (websites like this one) of the liability of an oil tank. We find that some people will hide the evidence of the tank and hope that no one looks for an oil tank, since the home is now heated by natural gas. Do you find it hard to believe that someone would try to hide the truth? Follow this story.

Home went under contract, home inspection and all, everything but a tank sweep with GPR was performed by the purchaser of the home. One day before settlement the prospective homeowner does a walk through of the property and low and behold someone spray painted "tank" on the ground. (this is a true story. I couldn’t make things like this up).

Why tank sweeps with GPR are important

 

Home was a flip, so the owner (really owner for 7 months) had no knowledge of any oil tank. Curren scanned the marked area and bingo oil tank, about ¼ full of oil. We can only speculate as to why the tank was hidden and why someone spray painted tank on the sidewalk. The general theory is a neighbor was aware of a tank at that location and also aware the owner removed evidence of the tank. Presumable the neighbor removed their tank and didn’t appreciate the neighbor not doing the right thing and removing theirs. We believe this is a likely scenario as we have seen it on other sites that we have performed tank scans/sweeps. People will park cars in driveways over tanks. People will say a tank was removed and we scan the area and find a metal object indicative of a tank.

oil tank sweeps find tanks



We even have people who have removed their own tanks, we get contracted to do soil borings and soil sampling from the removed tank area. $35,000.00 later, we find that the tank did leak, the owner just thought that oil is naturally present in a removed tank excavation.

 

Leaking removed oil tank cleanup

Bottom line you cannot rely on statements from a seller such as these:

There is no oil tank.

That the tank was removed

The removed tank didn’t leak.

Do you need to complete a tank sweep? Yes, if the home was built before 1980 and you can’t get 100% written documentation that natural gas was always utilized to heat the dwelling.

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Top 8 Reasons Why You Need a Tank Scan.

Nov 11, 2019 11:45:00 AM / by Tiffany Byrne posted in OIl Tank Sweeps, tank scans

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Buying a home is one of the top ten most stressful situations in an adult’s life. The stress of the inspections, cost of inspections, time and effort put into buying the home is extensive. The amount of inspections one will go through to buy a property could be, at least, totaling six (6). One of those inspections should include searching for an underground oil tank.

Underground oil tanks have a finite life span and were not built to last forever. If you forego the tank scan, you may have just bought yourself an underground oil tank. If the tank leaks you could be faced with a large and pricey problem. Not all recent homeowners are even aware that they bought a home with an underground oil tank.

Top 8 Reasons for a Tank Scan:

1. House built before 1980.
2. Above Ground Oil Tank.
3. Fill Pipes.
4. Vent Pipes.
5. Copper lines are visible.
6. Neighborhood that typically has Underground Storage Tanks
7. Furnace Chimney.
8. Previous tank scan was done with a magnetometer.

House built before 1980
If the house was built before 1980 you should presume that there could be an underground oil tank unless the seller provides you information otherwise. But beware, if a tank scan was done with a magnetometer, the scan may not have been enough to identify an underground oil tank. Ground Penetrating Radar is the most advanced technology used in today’s market to identify buried tanks.

IMG_4352

Above Ground Oil Tank
Prior to oil used as the main heating source, coal was providing the heat in the home. Coal was difficult on the homeowner, as you would have to shovel coal every 4-8 hours to keep the heat on. After coal, oil tanks became a popular heating source. The tank was buried as it was not an added value in the property aesthetics. When homeowners believed that the underground oil tank was no longer working, or it was time for a new tank an aboveground oil tank was installed. In essence, if there is an aboveground oil tank than there is a possibility that an underground oil tank exists on the property.

Fill Pipe

Oil tanks have fill pipes where the oil is distributed to the vessel. The fill pipe is attached to the oil tank and is what the oil delivery company uses to fill the tank with oil. If the fill pipe is noticeable during the home inspection, then that is a sign of an underground oil tank.



Vent Pipe
The vent pipe on the oil tank allows air/fumes to escape from the tank when the fuel is being added. The vent pipe commonly has a mushroom like cap to keep water from entering the oil tank. If a vent pipe is visible than that is sign that there my have been an underground oil tank at the property. If only a vent pipe is found then that means the tank may have been abandoned in place, meaning filled with sand or another inert material.

Copper Lines in Basement Leading to underground oil tank-1

Copper Lines
The oil fuel lines are made of copper tubing (lines) that allow the fuel to move from the tank to the furnace and back to the tank. The supply line provides the fuel from the tank to the furnace and the return line supplies the fuel that was not used back to the tank. If there is any evidence of current lines or lines that were cut, then there may have been an underground oil tank.

 

 

Neighborhood
Neighborhoods start with one home, moving to many, many more homes. Each neighborhood has a timeline, starting with the first home built. If this home was built prior to the 80’s than there is a possibility that a tank was on the property. The neighborhood may not have had a gas hook up line till after the homes were built, meaning there needed to be another source of heat prior to gas. If the neighborhood homes were built prior to gas in the neighborhood that it is likely that there is another source of heat and that could mean an underground oil tank.

A Furnace Chimney
In many old homes the chimney was not just used for wood burning, it was used for coal or oil. Check the chimney and see how many flues there are.

Previous tank scan with a Magnetometer.
There have been many instances where Curren Environmental is called upon to determine whether what the previous metal detector tank scan found is an underground oil tank. Metal detectors find any metal in the structure or asphalt/concrete. A/C units, reinforced concrete and chain link fences all have metal. There have been water lines and sewer lines that have been thought to be underground oil tanks, or on the flip side they were thought to be sewer or water lines and not an underground oil tank. To save money on inspections, start with the Ground Penetrating Radar not with a metal detector.


More questions?  Call our office today and speak to someone in person.

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Why performing a tank sweep is important when buying a home.

Feb 18, 2019 11:05:23 AM / by david sulock posted in tank leak, OIl Tank Sweeps, tank scans

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Why performing a Tank Sweep?

There are many inspections performed when buying a home, and most are cursory visual inspections of the HVAC system, soffits, chimneys, foundation, plumbing, sidewalks, decks, swimming pools, etc.  These building components are commonly evaluated as part of your home inspection.  What is missed by many buyers is the environmental liability aspect of purchasing a home. Environmental can be asbestos, radon, mold, lead paint and oil tanks.  Of all these environmental liabilities, oil tanks represent the biggest risk relative to remedial cost.  A hidden underground oil tank can cost a couple thousands of dollars to a new homeowner if it's not caught during the inspection process.  Worse is when an oil tank leaks, which can lead to costs into the tens of thousands of dollars.

 oil tank scan

When people are on the fence about doing a tank sweep, all I tell them is not to be surprised that when they sell the home in the future and a tank sweep is performed by that buyer.

Over the past 20 years oil tank sweeps, oil tank scans and/or oil tank inspections have become a common part of the home buying process.

Why perform an oil tank sweep?

Oil tanks belong to a property and if you buy a home with an oil tank you bought all the costs associated with the tank, meaning tank removal, soil testing and most expensive remediation (if required). 

The photo below is a remediation of a leaking oil tank.

oil tank leaking-5

Oil heat was popular in the Northeastern United States from the 1930's to the mid 1980's, this time frame encompasses a large part of the homes in the Northeast, meaning chances are the home you are looking to purchase utilized oil heat in the past.  Also homes built before 1930, most likely had oil heat. since coal was phased out as soon  as a homeowner had a chance to switch, since coal required physical feeding the furnace several times a day during the heating season.

More info on Tank Sweeps

 

What percentage of tank sweeps find prior oil heat?

With over 20 years experience with oil tanks, we have crunched the numbers and find an average of about 75% of the tank sweeps find evidence of prior oil heat.  That number should not be that surprising since natural gas really only became popular in the 1970's.

Who pays for a tank sweep?

Buyers typically pay for the tank sweep as it is part of their due diligence.  Due diligence is what a reasonable person would do to investigate a property for problems prior to ownership.

Do property owners ever do tank sweeps?

Most property owners do not perform tank sweeps as they do not want to find an oil tank.

 

The photo below shows a tank found by Curren during a GPR scan.   Home built 1978, sold in 2016, with no  tank sweep.

oil tank sweeps for home purchase

 

Tank scan with Ground Penetrating Radar (GPR) or metal detector?

You should use both GPR and a metal detector to be thorough when performing a tank scan or tank sweep. Rely on GPR the most as it is what commercial sites use, metal detectors are more to prove that the object found by GPR is metallic.  Remember, the best equipment is the most expensive, an $800.00 metal detector on Amazon.com should not be relied upon.

 

Tank Sweep Questions?

 

Metal detectors beep if they find iron sand (a real thing), buried pipes, get too close to a metal fence or a structure with metal (yes homes have metal) or simply encounter buried metallic trash.   GPR uses a screen so the geophysical technician can see the graphical image detected by the GPR antenna.     Larger signals are tanks, smaller signals are usually pipes.

Tank sweeps with GPR

Do you need a Ground Penetrating Radar/ Tank Scan?  Call Curren Environmental Today.

1-888-301-1050 

 

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How long does an Oil Tank Last?

Mar 6, 2018 4:01:00 AM / by David C Sulock posted in oil tank removal new jersey, oil tank removal nj, tank removal grants, tank leak, OIl Tank Sweeps, oil tank

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What is the life expectancy of an oil tank?

How long does an oil tank last?  When do you replace an oil tank.  These are popular oil tank questions.  All things have a finite life expectancy. Both aboveground storage tanks (ASTs) and underground storage tanks (USTs) have a usable life. The problem is your tank can fail (holes appear) and you may never notice.  An industry average for the life span of an oil tank is 20 years, some tanks last longer and some shorter.  This time frame is greatly dependent on the type of oil tank, construction of the tank (meaning thicker walled tanks generally can last longer). environment the tank is in (indoor - outdoor),  and the contents of the tank.  Harsher environments tend to shorten the lifespan of pretty much anything, including steel tanks. 

 
my oil tank leaked

 

When I ask people how long they think a tank is supposed to last I typically get silence or "I don’t know".   Then, I tell them thank you for not saying "Tanks last FOREVER".   A simple rule of replacement is if the roof has been replaced, so should the tank.    This is for all the people who are using a tank TODAY and if your house was built between 1950 and 1995, your tank is beyond any reasonable expectation of usable life and should be replaced.  No there is not a likely possibility that the original tank from the day your house was constructed has been replaced.  The saying 'if it isn’t broken don’t fix it' is unfortunately followed when it comes to oil tanks.   Simply put, if people replaced tanks within a reasonable amount of time, you wouldn’t have tank leaks and expensive environmental cleanups.

How do oil tanks leak?  Many oil tanks rust through from the inside out.  This most often occurs when the oil is not present, meaning upper portion of the tank where the tank is empty and the oil is not present to lubricate the steel.  Tanks can also leak due to the use of low sulfur fuel.  Heating oil tanks that have low sulfur fuel and water can allow microbial growth to occur.  Secretions from these microbes can produce acids that can corrode a steel tank.

 

oil tanks can rust from the inisde

The photo above is the inside of a cleaned and cut open oil tank.   What is really interesting is the rust you see on the bottom of the tank.  This is the corrosive effect of the microbial activity in the tank.  Yes an oil tank can corrode from the inside of the tank.

 

 

Click Here to Learn about Testing Oil Tanks for Leaks

Aside from corrosion inside the tank, an oil tank can deteriorate from the outside due to environmental conditions.   Rust never sleeps and for corrosion to occur you need metal, oxygen and moisture.   How fast a given metal rusts is based on the environment the metal is exposed too. 

 

Holes in Underground Oil Tank

 

Aboveground oil tanks may look fine from a cursory exterior view but in fact, could heavy corroded on the inside and be ready to fail. 

Underground oil tanks are thicker than comparable aboveground tanks due to a more corrosive environment.  In short, an indoor rated AST is thinner than an outdoor rated AST, which is thinner than a buried UST.  Curren has found that there is a wide variation in indoor aboveground and outdoor aboveground oil tank life spans due to the considerable variation in both the quality and thickness of steel (older tanks seem to have been a heavier gauge steel), which helps prolong the life of the tank.

 

Tank Questions? Click Here

We have seen indoor oil tanks in good condition that are 60 years old or older, and we have found failures in newer oil storage tanks that may have been made of thinner or cheaper steel and that did not last as long as the original ones.  The tanks made immediately following WWII are of higher quality, saying things are not made as good as they used to be is a very true statement when it comes to oil tanks.

Rather than guess a tanks oil tank condition, we suggest that if your home has an older aboveground oil storage tank, twenty years old or older, you should replace the tank.  Keep in mind many brand new oil tanks have a 10 year warranty.

What Can Cause an Oil Tank To Leak?

  • Exposure of the oil storage tank to wide temperature swings, especially in cold and humid climates can increase in-tank condensation (water)  leading to corrosion.
  • The oil inside the tank corrodes the tank.   How is it possible that oil can corrode metal.   Bacteria forms in the tank from moisture (condensation), since we want clean air EPA has mandated that the sulfur content in fuel is lower.  An environmental such as a tank of oil with low sulfur is actually a conducive environment for bacteria.  So now you have bacteria thriving in the tank as part of their biological activity corrosive compounds are created from the bacteria that corrode the tank.  You got all that?
  • Above Ground oil tank Leaking
  • Exposure of the tank fill or vent pipes to rain, especially to roof runoff for tanks mounted under the eaves of a home and especially if the oil fill cap is not securely tightened after filling with oil.  You see the rain water soaks the soil around the tank which hastens corrosions.  Tanks under concrete and asphalt tend to last longer as they are shelter from rain.
  • External oil tank rust due to exposure to the weather. Many small tanks, 275 to 300 gallon tanks were used for unintended uses.  Meaning many of these size tanks, were never rated for outdoor use, but have been used for outdoor use and some even buried.   You can tell what use a tank is rated for by reading the UL label that is affixed to the top of the tank.  Manufacturers of newer oil storage tanks in this size range often have removed this "indoor use only" wording from the UL label.
  • The tank in the photo was a basement tank, but was buried.  The tank was not rated (designed) for burial.  It leaked as the tank was not thick enough for the harsh environment of a buried tank.
  • 290 gallon tank AST was buried
  • Improper oil tank installation.  Meaning the tank was not designed for the current use.  We have found indoor oil tanks that were moved outside and placed onto the underground in the soil surface below a deck, and then partially to half buried. What is this tank, an underground tank or an aboveground tank?  (The government definition of a UST is one where 10% or more of the tank is buried below ground.) These tanks were not rated for outdoor use at all and are at extra risk of leakage due to placement of the tank body directly in contact with the soil.
  • damaged in use AST
  • Improper oil storage tank supports, such as failure to keep the outdoor tank off of the ground, to install it at the proper pitch and direction of pitch, and to install it on level surface, unsecured legs of the tank can lead to the tank tipping over, ripping open an oil line, and obvious discharge of oil from the tank.   This is more common with out-of-service tanks.

Want information on tank removal? Clock here Oil Tank Removal

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Oil Tank Sweeps - Inspecting Properties for Tanks

Aug 15, 2017 2:35:00 PM / by pat warren posted in OIl Tank Sweeps

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Have you ever gone to the beach and used a metal detector and found pennies, nickels or dimes? Or even paper clips maybe a thumb tack or that gold chain?  Did you really ever find that diamond ring or that emerald necklace that would be like winning the lottery? I didn’t think so. That’s what it’s like using a metal detector to find an Underground Storage Tank (UST).  There are so many different metal detectors available for anyone to buy today.  It’s like hiring someone with an $800 metal detector who will charge you $200 to find a penny. Is that what you are looking for?

What do the following items have in common: A/C units, chain-link fence, reinforce concrete and underground utilities? They all contain metal.  The major problem with only using a metal detector to locate tanks is that all homes have a large amount of metal surrounding the structure.

There have been many instances where Curren Environmental has been called out to a property after a “metal detector tank scan” had been performed because the findings were inconclusive.  In most cases the recommendations of the tank scan company was to either dig it up or have a GPR scan performed! One severe case for example – a homeowner purchased a property after having a metal detector scan performed and was now looking to sell.  A potential buyer of the property had Curren perform a GPR scan and sure enough a UST was found.   The UST was removed and found to be leaking—the cost of the remediation was over $20,000.00.  Don’t buy a home with an UST that couldn’t be found with a metal detector.  

Ground Penetrating Radar is (commonly called GPR) a geophysical method for tank scans that has been developed over the past thirty years for shallow, high-resolution, subsurface investigations of the earth. A Ground Penetrating Radar (tank scanning) unit costs well over $15,000, which a trained technician uses to locate an Underground Oil Tanks.

USTSWEEP.jpg

  

GPR uses high frequency pulsed electromagnetic waves (generally 10 MHz to 1,000 MHz) to acquire subsurface information to locate the Underground Oil Tank. Energy is propagated downward into the ground and is reflected back to the surface from boundaries at which there are electrical property contrasts.

The GPR unit is mounted on a cart that is manually pushed.  The use of GPR is based on a radar signal penetrating the ground and the signal reflecting off solid buried objects such as Underground Oil Tanks.  The signal will attenuate when it passes over solid ground cover such as concrete, asphalt, pavers, etc.  Optimal scanning conditions would be unpaved non-landscaped areas.  A metal detector will pick up any rebar in the concrete or pavement.

 

Buried UST Found by GPR.jpg

Ground penetrating radar (commonly called GPR) is a geophysical method that has been developed over the past thirty years for shallow, high-resolution, subsurface investigations of the earth. GPR uses high frequency pulsed electromagnetic waves to acquire subsurface information. The tank scanning unit also provides the ability to scan the ground for not only copper lines, cables and pipes but the advantage over a traditional, metal detector or magnetometer is that it can see non-conductive materials including plastic pipes.

Using radar technology, the displays shows image map of underground features. The unit allows real-time subsurface displays and adjustable digital color to provide immediate sensing technology in lieu of data capturing and downloading to observe the findings as with other GPR units. Something you WILL not see with a metal detector.  

Tank Sweep.jpg

Remember – a metal detector can find anything metal in the ground.  A Ground Penetrating Radar will scan the ground for an Underground Oil Tank.

 

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