Underground Oil Tanks & What They Mean For Your Home

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Rusted, decommissioned oil tank dug up and sitting on a residential sidewalk. Credit Joshin Yamada.When putting your home up for sale on the market, you want to pinpoint any problems that could affect your home's selling price before the deal is struck. Sometimes these problems are general issues that all home owners are susceptible to, and other times they can be specific to your city or even your neighbourhood.

Underground oil storage tanks (or USTs) are one such issue specific to BC, and older Victoria neighbourhoods in particular.

In the early days of Vancouver Island, the vast majority of homes were heated by oil furnaces. These furnaces had their fuel tanks buried underground to preserve space, hide a potential eyesore, and limit the risk of fire. With oil capacities ranging from 200 to 1000 gallons, the tanks were often buried in side yards and backyards.

In 1957 natural gas was introduced to the island, and in 1960-1961 homes began to switch over en masse to natural gas furnaces. In most cases homeowners who changed over to the new system had their old oil tanks drained of fuel, then left them buried in the ground... but not always.

Now, more than 50 years later, these tanks are causing environmental hazards on Vancouver Island and in mainland BC. Depending on manufacturing and soil conditions, most oil tanks will only last 10 to 20 years before they start to seriously rust and corrode. At that point, any remaining oil will begin to leach into the surrounding soil and drainage systems — and in some cases that can be a full tank's worth. In other cases, empty tanks (or even old tanks still in use) can accumulate water, furthering the tank's destruction and damaging existing heating systems.

In 2011 alone there were 28 contamination spills from aged oil tanks in Victoria, and more often than not the cost of cleanup fell squarely on the homeowner's shoulders. Homes built before the 1960s have the highest risk of hidden buried tanks on their property, and in many cases the homeowners were not aware of the issue. Property disclosure forms include a line referencing oil tanks, but many mistakenly believe that because an above-ground oil tank was removed, their property isn't likely to have an underground oil tank as well.

In the majority of cases, homeowners don't realize a tank is present until they make to sell, insure, or mortgage their home and the inspection turns one up. In those situations, the earlier a tank can be detected, the better. You can make use of free oil tank sweeping services offered by Victoria Tank Services in the Greater Victoria area, or similar services offered by ScanPlus GPR Locating & Mapping in the Sooke and Langford regions.

If a tank is found and is still full, it will need to be rendered inert. If it has already leaked, soil and groundwater cleanup will need to be carried out on your property. Inerting a tank can cost anywhere from $500 - $1000 while remediation for a leaking tank can cost well upwards of $2000, so catching a tank before it can leak is your best option.

Depending on the municipality you live in, you may be able to leave the tank in place after verifying it's inert, or you may be required to completely remove it. In Oak Bay, for example, underground oil tanks can be inerted or removed, so long as the process is confirmed and documented by the Oak Bay Fire Department. You should check with your local municipal hall or fire department to determine the requirements for your area, or ask a certified REALTOR®.

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