After removing the old grass I left a lot of pieces of turf. Pity to throw - like not quite dead. Is there a way to reuse it? Maybe transfer it somewhere to grow new grass? Or better recycle it all? So far I put everything in a heap, but I do not know what to do with it. Do not want to throw away if you can somehow apply.

You can use old grass after lawn renovation in two ways. If the grass is still alive, just roll it in places where the grass is rare. It will settle and help to even out the emptiness. If there is a lot of old grass or weeds, cut it into pieces and add to compost. In a few months, you will make a great organic fertilizer. The main thing is not to leave a pile on the ground - there will be pests. Better to use or recycle.

Good advice about compost. I did that too - old dirt really decomposes quickly and makes the soil loose. It is only necessary to turn the pile from time to time, so that the smell does not go. And if somewhere on the plot of a pit, you can put there old layer, on top of the ground - and you get a flat surface. It is economical and useful.