If you leave them for long enough, even bonfire heaps develop interesting characteristics... here is one that I have been filling and burning for several years:
..well, technically, I guess that I am the one that has been filling it, and the client is the one who has been burning it... anyway, it's a bonfire heap of long standing, always in the same place.
Here is it having just been burned off, and you can see that it's developing a conical shape. Almost as though it has delusions of becoming a volcano...
My usual practise, when arriving at work to find that the bonfire heap has been burned, is to a) congratulate the client (I like to encourage them to burn off, then I don't feel so guilty about creating huge piles of material to be burnt...) and then b) to rake out the ashes into a level platform.
If you don't do this, the new pile becomes a conical heap as well, and gets wider and wider as the stuff falls off the top of the heap. By raking it into a level platform, you can get a lot more on the heap before it needs to be burned off again.
The other useful thing about bonfire heaps is that the ash is sterile - no weed seeds, no germs - which means it has a variety of uses around a large garden. In one of mine, I use the ash to fill in a set of steps made up of thick wooden planks held in place by angle iron, which tend to sink and become trip hazards. The ash has a nice texture for step in-fill, is less muddily "sticky", and is less prone to compaction than using mere earth. And, of course, it doesn't sprout a toupee of weeds on every step.
In this case, I wanted to use the ash to spread around a path made of huge stones set in earth - again, the earth around them had sunk a little, and they were becoming trip hazards, especially for ageing clients and visiting grand-children. So I was particularly pleased to find the bonfire pile was all gone, and set to work digging out the ash and redistributing it.
Much to my amusement, there were clearly defined strata in the ash - rather like those glass ornaments filled with different coloured sands... I dug down about two feet, somewhat surprised at just how deep the ash was - you can see the scale by my glove, helpfully lying on the new flat bottom of the heap.
Interesting, huh? It was all ash - none of it was soil - but in very different colours.
I then spent the rest of the morning barrowing loads of the stuff out to my working area, which was hard work, but well worth it.
Here's another bonfire heap which needs to be being raked flat: here it is after a typical "burning" - it's just a mess of half-burned stumps, metal bits, and ash, and it forms a slope which means that as soon as I try to stack more material on it, it slides forward and blocks the path.
This is annoying for me, and for the client as well, as it means I start pestering them to burn it again, quite quickly.
However, if I get to it first, I can rake it all flat, like so:
...which gives me a good big base for stacking the new material, which you can see is already arriving, even while the ashes are still smelling of smoke.
As an aside, in case you're interested, I do have views about bonfire technique: when I'm volunteering down at the canal, I never let them burn off the stacked material, I always start a bonfire with a small neat pile of dry material, then pitchfork the stack across onto it once it gets going.
This allows all wildlife in the heap a chance to escape.
Whereas if you just shove a firelighter into a heap that has been building up for months, the residents all get toasted.
I always try to encourage my clients to work to this principle, by creating a burning site in one place, and a stacking site close by. However, I can't insist, and some of them just set fire to the single heap, and that's that: but at least I can encourage them to get a long pole or a fork and agitate the heap from one side (ie not walking all round it) before lighting it, to give anything with legs enough time to scoot away to safety.
So there you have it - if your garden generates a lot of non-compostable waste, and you have room to burn it, designate an area for the actual burning, and stack everything to be burnt just to one side: pick a spot without overhanging trees, and pick a day that's not too windy. Traditionally people like to burn on still days, as then the smoke doesn't scare or annoy the neighbours, but sometimes a bit of a breeze can help the fire to burn well. Too much wind, however, and you get smoke in your face all day long, singed eyebrows, and if you are really unlucky, a visit from the fire brigade, who will be understandably annoyed if your neighbours have called them out for no reason!