Spontaneous Combustion

by John Robertson

At 0708 on 7th March we got a page to a fire at the green waste dump at Knoll Road. TM52 was first off with Barry and Robbo. 52 was at the fire at 0724; not a bad response time for volunteers! TM51 followed close behind with John (TM1), Neville and Rory. There was a lot of smoke coming from the large pile of green waste.

Council staff were on hand and we used their tractor backhoe plus one of our own rakehoes to open up and spread the smoking material while 52 and 51 hosed down the hot spots within it. We had suppressed all the smoke within about 20 minutes. The Council staff undertook to monitor the situation and hopefully we will not hear further from them.

John correctly identified spontaneous combustion as the cause of the problem. On close inspection it was evident that fungal growth caused the initial heating which built up to full internal combustion. It was further evident that the whole amount of the large green waste dump was subject to the same process. Given the weather conditions and the age of the material the dump was too massive and too high to avoid internal combustion. John advised the Council to get their contractor on site to reduce the height and to spread the entire mass over a greater area.

We were all back at the Station by 0815 and dispersed after a short debrief which included thanks and congratulations all round from TM1.
However, that was not the end of the story.
On Saturday afternoon Maureen, our former Brigade Secretary, told John that the dump was again smoking vigorously. John arranged for Firecom to page us which they did at 1500. Tony was on base radio and, via many phone calls, got hold of Dean Coles (the Council’s contractor) and organised for him to bring a Bobcat loader to the dump. TM52 with John (TM1) and Neville were first up followed by John F and Robbo in 51 and by Dean with the Bobcat. As we saw on Friday the whole mass was subect to internal combustion and this latest episode had been set off by members of the public loading mulch from the pile thus letting in air and re-starting vigorous combustion which included considerable flames. Indeed when John and Neville arrived one person was busy loading his ute with burning mulch. As Neville observed he could be quite sure that it contained no viable weed seeds. Expert operation of the Bobcat by Dean soon excavated the hottest part of the heap and spread it about one metre high. As he did this, 51 and 52 hosed it down and also hosed down the face of the pile where he was digging. John F ran the pump and foam on 51 with a skill born of long experience and with perfect consideration for the guy on the branch.
John had Dean cut a wide earth break around the pile to protect the adjacent forest; a score of good operators with rake hoes would have been pushed to do this so well in the time. Finally John had us lay thick foam on the main pile and on the spread material; this wetted down the mulch and helped seal out the air. That done both trucks went to refill with water at Holt Road. Dean assured us that on Monday the whole heap would be excavated and spread out safely.
We were back at the Station by 17.30 for a short debrief where TM1 congratulated the members present and they congratulated John on a job well done. John undertook to monitor the fire in the evening and when he did this more smoke was coming from the big heap. John called Nev to join him in 52, they hosed down the face thoroughly and were back at the Station at 2230. Nev described the face as looking like the lava flow from a volcano.
Early on Sunday morning Nev did a recce and reported a bright red spot in the middle of the face. Later in the morning and in response to Nev’s report Coles brought a long-reach backhoe onto site to make a complete job of spreading out the big heap. It was evident that the internal combustion had extended right throughout the lower levels of the heap. TM52 with John and Nev hosed down each scoop of hot mulch as it was spread. Paul and Kim came in 51 and laid foam over the entire area of mulch. The trucks recommissioned and were back at the Station at 1130. Kim undertook to monitor the fire and happily was able to report that all was well. So this incident really is at an end!
Posted in Incident Reports