How to Tell If Your Underground Oil Tank Is Leaking

Underground oil tank leak

Roughly 5.3 million homes in the United States rely on oil heating for their homes. Some of which may have underground oil tanks. Unfortunately, these tanks can suffer from cracking and other forms of corrosion that lead to a dangerous situation – oil leakage. The presence of an underground tank on your property should be taken very seriously, as it could present a significant hazard to the environment, your health, and even your wallet.

Knowing the signs of a potential underground oil tank leak can help homeowners mitigate costly repairs and potential environmental damage. Here’s a look at what to watch for:

What Can Cause an Underground Oil Tank Leak?

Cause of oil tank leak

Before we dive into the signs of a potential oil tank leak, it’s important to understand how they occur. Below are some common culprits that can cause your underground oil tank to rupture and start leaking:

The Age of Your Underground Oil Tank

A well-maintained underground oil tank should last around 30 years before it needs to be removed or replaced. Yet, as an underground oil tank ages, its structural integrity decreases, and the likelihood of a leak increases. In addition, materials used to create underground oil tanks were less durable in the past, so older tanks may be more prone to cracking and leaking.

Corrosion of the Underground Oil Tank

Underground oil tanks are often made of steel (or similar materials), which can weaken over time. Corrosion can occur due to exposure to moisture in the soil, as well as from corrosive byproducts generated within the tank itself. So, if you own an older underground oil tank, it’s even more important to have your tank checked for corrosion.

Ground Movement Causing the Leak

Movement of the ground beneath or around an underground oil tank can cause the tank to leak. A variety of activities, such as nearby construction, earthquakes, and even tree roots, can cause shifts in the ground and put stress on your tank. This can weaken or crack the tank, leading to a leak.

The Weather

Inclement weather, such as heavy rain or snow, can also cause an underground oil tank to leak. When water seeps into the ground around your oil tank, it creates hydrostatic pressure that could cause a rupture in the walls of your tank. It’s important to monitor your oil tank during periods of heavy precipitation and keep an eye out for any signs of a leak.

Common Signs Your Oil Tank Is Leaking

Oil sheen in water

Now that you know what an oil tank leak is, let’s take a look at the signs to watch for. If you notice any of these signs, contact a professional inspector right away:

An Oil Sheen in Your Water

If you notice an oily sheen on the surface of the water around your home, it could be a sign that your underground oil tank is leaking. The oil may have seeped into the nearby groundwater and created a slick coating across the top of any standing water sources – such as ponds and streams.

This type of contamination can be very dangerous and should be addressed right away. Contacting a professional to inspect the area will help protect your home, as well as nearby properties, from potential damage caused by the leaking oil tank.

A Significant Increase in Your Heating Bill

If you notice a sudden and unexplained spike in your heating bill, it could be a sign that your oil tank is leaking. Leaks can lead to a loss of oil, which will increase your energy usage in order to compensate.

So, if you’ve ruled out other causes for the rise in your heating bill, it may be time to contact a professional to search to assess your underground oil tank for potential leaks. They will be able to help you determine how to best address the issue and restore your home to a safe and efficient environment.

Plants Dying Around Your Oil Tank

Another sign of an underground oil tank leak is dead or dying plants and vegetation near your home – especially in the area where the underground oil tank is located. This is because the oil leaked from the tank can seep into the soil and contaminate it, killing vegetation.

As such, dead or dying plants could mean the leak has been present for some time and should be urgently addressed. Leaving it unresolved could cause further environmental damage and even affect neighboring properties. So, be sure to contact a professional to inspect and assess the situation as soon as possible.

The Smell of Oil

If you notice a strong, pungent smell around your home that is similar to diesel fuel, it could be a sign of an underground oil tank leak. This is because the volatile compounds in oil can evaporate into the air and create a vapor – which has its own distinct smell.

This odor can cause headaches, nausea, and other health problems if it is present around your home for a prolonged period. If you smell the scent of oil, contact a professional inspector to come and assess your property. In some cases, removing the oil tank and cleaning up the area may be necessary – so don’t hesitate to get help immediately.

10 Crucial Steps to Determine If an Underground Storage Tank Is Leaking or Not

10 steps to help detect leaking underground oil tank

1. Visual Inspection

A visual inspection is the first step in assessing a UST’s condition. Look for any visible signs of leakage, such as stains on the soil, wet spots, or discolored soil around the tank and associated piping. These visual cues can be indicative of a leak.

2. Groundwater Monitoring

This method is too expensive for most homeowners 

Installing monitoring wells around the UST site can help detect leaks. Regularly sample groundwater from these wells and analyze it for the presence of contaminants, such as petroleum hydrocarbons or chemicals associated with the stored substances.

3. Soil Testing

Best method but not 100%

Conduct soil tests near the tank to check for contamination. Soil samples should be analyzed for the presence of pollutants. Elevated levels of contaminants in the soil may indicate a UST leak.

4. Leak Detection Systems

Cost prohibitive for residential use 

Consider using advanced UST leak detection systems, like automatic tank gauging systems, interstitial monitoring, or vapor monitoring. These systems can provide real-time data on UST conditions and help detect even small leaks.

5. Inventory Control and Reconciliation

Best for gas stations 

Keep meticulous records of the substances stored in the UST, deliveries, and withdrawals. Regularly reconcile the inventory with actual usage. Discrepancies may indicate a leak.

6. Non-Destructive Testing

Cost issues

Non-destructive testing methods, such as ultrasonic testing and ground-penetrating radar, can be employed to evaluate the tank’s structural integrity without excavating it.

7. Soil Gas Monitoring

Excellent method for ongoing monitoring 

Measuring the concentration of volatile organic compounds (VOCs) in soil gas can help identify leaks. Elevated VOC levels in the soil gas can clearly indicate UST leakage.

8. Professional Inspection

Consult with experienced professionals, such as environmental consultants or geologists, to thoroughly assess the UST site. They can employ various techniques and instruments to determine whether a leak exists conclusively.

9. Regulatory Compliance

Ensure compliance with local, state, and federal regulations regarding UST monitoring and testing. Many regulations require regular inspections and reporting, which can help identify leaks.

10. Preventive Maintenance

Regular maintenance and integrity testing of USTs can go a long way in preventing leaks. Timely repairs and upgrades can help extend the life of the tank and minimize the risk of leaks.

Final Thoughts

Oil tank search and removal

Determining whether an underground storage tank is leaking or not is critical for protecting the environment and public health. Combining various monitoring methods, visual inspections, and professional assessments can provide a comprehensive understanding of a UST’s condition. Regular vigilance and compliance with regulations are essential in preventing and detecting UST leaks to minimize their environmental impact.

Having stated all the obvious methods to check on an underground tank, the real answer is to remove the tank and install an above-ground tank. Our approach toward UST testing and monitoring is that Removing UST is always Best. Once out, it’s gone forever. 

At Certified Environmental Contractors, we specialize in providing top-tier oil tank inspection and removal services. Our experienced team of professionals is available to assess any potential issues related to underground oil tanks and provide the best solutions for your specific needs.

Contact us today to learn more about how we can help you keep your home safe from leaks!

Published: March 14, 2023

Updated: December 8, 2023

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Peter Lordy

Peter Lordy is a seasoned environmental expert with over 30 years of experience in Superfund, industrial/commercial, residential site evaluations, and regulatory compliance including RCRA and CERCLA. He is a trained asbestos removal supervisor, holding various licenses from NJDEP for closure, subsurface, and tank testing. As a Rutgers-trained hazmat trainer, he possesses the required 40 hours of training for annual certification, alongside being Roth Certified. Peter is also a voting member of ASTM International and a Radon Measurement Specialist, demonstrating his broad expertise and commitment to environmental safety and standards.