Curren Environmental Blog

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

Posted by david sulock on Feb 18, 2019 11:05:23 AM

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 

 

Tags: OIl Tank Sweeps, tank leak, tank scans

How long does an Oil Tank Last?

Posted by David C Sulock on Mar 6, 2018 4:01:00 AM

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 pic2.jpg

 

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.

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 1 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 leading to corrosion
  • 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.  
  • 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.
  • Improper oil tank installation  of improper oil tank type.  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.
  • 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

Tags: oil tank, tank leak, OIl Tank Sweeps, tank removal grants, oil tank removal nj, oil tank removal new jersey

Oil Tank Sweeps - Inspecting Properties for Tanks

Posted by pat warren on Aug 15, 2017 2:35:00 PM

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.

 

Tags: OIl Tank Sweeps