The Belconnen tip has been evacuated after fire engulfed a large rubbish pile at the landfill site on Sustainability Road.
The fire is not near the Mr fluffy demolition waste.
Fire crews are working to extinguish the blaze which had been burning for several hours on Tuesday by the time units were called in, shortly before 2pm.
They are waiting for machinery to beak apart the pile, that is about 15 metres high, 40 metres long and 30 metres wide
Firefighters wearing breathing apparatuses are using water and foam to bring the fire under control.
Hazmat crews and Workcover also attended the scene.