Boring But Important: Gas Station Vapour Recovery System, Explained

Gas stations typically have underground storage tanks for gasoline and diesel fuels. The newer tanks are designed to be resistant to corrosion, with a system to detect leaks anywhere on the line. Some tanks are fibreglass, some have double walls with the outer layer surrounded by brine, and steel tanks are used in locations where there is a large volume of heavy machinery on the ground above. Some stations have tanks with compartments for different grades of products.

I have no idea what kind of tanks are next door, nor whether they are a safe distance from my property. I do know they are close.

Underground tanks get filled by a tanker truck. They connect a hose from the truck to a sort of coupler attachment, which connects to the tank below. They also connect (or are SUPPOSED to) connect a second hose, using a second coupler device, which goes from the underground storage tank back to the truck. This is supposed to create a closed system, where the fuel vapours go back into the tanker truck, and are later processed to be reclaimed and turned into liquid fuel.

When there is a discrepancy in the pressure of the gasoline vapours, the excess vapours are directed to go out the vent pipes.

There is no way to make this process hermetically sealed.

This video is from 2006. It is about a type of new (then) camera technology that was developed, that makes gasoline (and other chemical) fumes visible. The footage when the inspector pops off the ground level covers for the underground tanks is pretty horrifying. The vapours blacken her face, hands, shoes and parts of her clothing with an exposure to the opened plate, that is less than 10 seconds. That is not even with them opened with the coupler device placed on top:

This is Stage 1 vapour recovery. Stage 2 is the special nozzles that are supposed to recover vapours while a vehicle is being filled at the pump. The Vapour Recovery system allegedly collects 96% of the vapours that would be released into the environment.

Here’s a simple diagram:

VaporRecovery.jpg

This is an excruciatingly boring educational video from 2012, produced by USA’s Environmental Protection Agency. It outlines how this system is supposed to work:

Since the first infiltration of gasoline vapours into my house (Aug/2018) I have been watching, and photographing the tanker trucks refuelling next door. The process takes about 20 – 30 minutes. On days when there has been NO perceptible gas infiltration, the process and equipment used appears identical to the days when there have been gas vapours in my house. It is the same operator, most of the time. The gas infiltrations have happened on warm days, cold days and very cold days. I have not been keeping track of other variables like wind speed or wind direction, humidity or barometric pressure. The gas infiltration is not happening with every refuelling.

When the TSSA inspector came the first time (Oct. 15, 2018 I think) he said the system had been checked and was working properly. Yet when he returned to observe a refuelling (Oct. 22, 2018), there were visible gas fumes coming from the vent pipe(s) and my front yard smelt very strongly of gasoline fumes. This time my house was not infiltrated.

I believe that no matter how the system is functioning – and it is designed to release excess gas fumes during a refuelling to relieve pressure in the tank – that the location of these vent pipes in relation to my property is unacceptable. Making taller or shorter vent pipes, or putting up a solid barricade wall will in no way solve this issue.

Ontario Regulation 455/94, under the Environmental Protection Act,” Recovery  of Gasoline Vapour In Bulk Transfers” states in Section 7 (Service Stations):

” 2. For each calendar year, the vapour control system must operate properly during 95 per cent of the time during which gasoline is transferred for receipt at the service station.”

https://www.ontario.ca/laws/regulation/940455

From the Government of Canada document CAN/CGSB-3.1000-2013 – Vapour Control systems in gasoline networks ICS 75.200 this statement is repeated, many times, in bold text: ” Discharge of flammable vapours may constitute a fire,  explosion, human health and environmental hazard.”

Click to access P29-003-1000-2013-eng.pdf

Yet there is nothing in ANY code that states what a safe distance from a residence of any type is, from a vent which discharges these vapours !

 

 

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