Underground Storage Tanks (UST’s) were commonly used to store domestic heating oil in urban areas when there was insufficient space to keep the tanks above ground. They typically vary in size from 300 to 2,000 gallons, depending on the number of people being serviced by the tank. Unfortunately, most of these tanks were left abandoned, often with residential heating oil left inside when owners switched to natural gas.
UST may be found on commercial, industrial properties and larger apartment complexes where bunker oil, diesel, hydraulic oil and waste oil may have been stored. Leaks from tanks associated with stationary hydraulic machinery may also needs investigation. Gasoline, diesel and waste oil tanks are more commonly associated with service stations.
Over time, a UST can deteriorate forming holes caused by age, neglect, and ground conditions. UST’s with fuel abandoned inside them can then leak into the soil and contaminate the property in the vicinity of the UST with petroleum hydrocarbons.
To determine whether or not a UST is present on a property, there are several indicators which should be investigated. UST infrastructures above ground include filler caps, air vents and fuel lines. Information gathered from Terasen might indicate that a UST was on the property before gas was installed. As well, persons familiar with the property should be interviewed about the historical land use of the property to determine if there was ever a UST on site. Metal detectors and locators can be used in determining the location of a UST. In addition, geophysical surveys such as EM can be performed, albeit much more expensive and with questionable results.
The property owner is generally liable for any problems associated with their UST if they sell the property, assuming that problems arise quickly. Purchaser may recover the cost of remediation as well as reasonable legal costs incurred. However, if the new owners have been in possession of the property for a long period of time before any problems were identified, they had enough time to correct the problem themselves and are likely to be liable for the problem now. However, if any reports, documents, or certificates exist stating that a UST is not present on the property at the time of transfer, then previous owners may be liable for any contamination occurring on the property. Likewise leaseholders are responsible for ensuring that properties are free of contaminants upon entering into a lease contract and also upon termination of lease, as landlord may seek compensation should contaminants be identified at a later date.
In the case where leakage occurs, extractable petroleum hydrocarbons will contaminate the area near the UST. Disposed of any remaining fuel and sludge and clean the tank. Soil samples should be collected to determine if the soil meets the applicable land use standards. If not, the most cost-effective method for remediation is generally removal of at least 90% of the contaminated soils with disposal to a licensed remediation facility or hazardous waste landfill. Removal or abandonment of tanks involves certification of the condition of the soil in the tank nest, tank location, or if abandoned the condition of tank needs to be certified as having been cleaned and prepared for abandonment. Normally tanks are abandoned if the structural integrity of foundations or buildings, etc. could be compromised by removal of tank.
Environmental site investigations are typically triggered when there is a land use change for a property or when the property is being sold. Investigations are commonly carried out for commercial and industrial properties where there is potential for contamination due to daily operations. Site investigations can be broken down into two components, a preliminary site investigation (PSI) and a detailed site investigation (DSI).
Stage I/II Preliminary Site Investigations
Preliminary site investigations can be further divided into Stage I and Stage II components. A Stage I PSI is typically used to screen a site for potential contamination. The information that is typically included in a Stage I PSI include:
- a visual site inspection
- a review of available historic information on the property, including a Site Registry search
- determination of land use of the subject property as well as surrounding properties and their commercial activities
- identification of possible contaminants and sources of contamination.
These findings are then collected and presented in a written report. The results of a Stage I PSI are then used to determine whether a Stage II PSI is required. A Stage II PSI typically includes:
- sampling and analysis of relevant environmental media
- assessment of the contaminants of concern and comparison of their concentrations relative to the standards in the Contaminated Sites Regulations (CSR)
The investigative work from the Stage II PSI are then presented in a written report to the client.
A Stage I/II PSI is used to determine whether or not there is contamination present at a particular site. If it is confirmed that the site is contaminated, the next step towards remediation is a Detailed Site Investigation (DSI).
Detailed Site Investigations
A DSI seeks to provide information on:
- substances that are causing or may be causing negative impacts on human health or the environment
- the extent of the contamination on the site, including the areas that are contaminated and the areas where contamination has migrated to
- relative severity of contamination relative to the standards established in the Hazardous Waste and Contaminated Sites Regulations
- the relevance of findings in the Stage I/II PSI on the design and implementation of techniques used in the DSI
- the data obtained through field observations, media sampling events and the associated laboratory analysis
- interpretation and evaluation of the above information in order to provide an understanding of the contamination on the site
These findings will be presented in a written report to the client.
Provincial Regulatory Guidance and Information
Vancouver Fire Department Fact Page
West Vancouver – Information on Residential Underground Fuel Storage Tanks
Government of Canada – Fisheries Act
BC Laws – Water Sustainability Act
BC Laws – Environmental Management Act
British Columbia College of Applied Biology
Professional Engineers and Geoscientists of BC