I have a field behind me and my neighbor is throwing his grass clippings in the field for years, ( the grass is treated with chemicals) I have 2 Doberman and they tend to go over and scratch the top of the pile and eat this grass ( I'm always yelling at them for the fear that this is very bad for them) At what time do these chemicals leave this pile or do I have to take other matters to get my animals not to eat this grass. Very concerned about my dogs. I have one now with bone cancer under her chin which I hope is not my fault from this grass.
Each herbicide has a unique half life. They are organic and will break down over time. If you know the herbicide being used, you can read a lot of good information about its toxicity in the MSDA (material data safety sheet). You can also call the manufacturer and ask about the half life.
The easiest thing to do is to add a thin layer of soil on top of the grass clippings and then layer dried plant debris over that, making a nice compost "lasagna". Grass clippings break down very quickly in this situation-maybe just a few days. Your dogs won't want to dig through all the layers to get to the fresh clippings. If you leave the layers to compost, you can let the herbicide break down over time.