Base spokeswoman Capt. Jenn Jackson says the leak in the 65,000-litre tank was discovered Tuesday afternoon at the Damage Control Training Facility in Colwood, B.C., while workers were conducting routine maintenance.
She says when the leak was discovered the tank was about half full.
Jackson says the Colwood Fire Department took over as the lead agency, before officials cordoned off a one-kilometre area around the leak and evacuated non-essential personnel who were within 800 metres.
She says the area is wooded and also includes some sports fields — no residences or businesses were evacuated.
Jackson says officials are now trying to determine how they can best control the leak.