Many national organizations provide important guidelines for every kind of operations. They usually take into account of the local regulation, so giving you a strict answer without knowing where the site is located can be hazardous.

I am personally familiar with the French regulation. In French, there are CARSAT (which is not this of organization, properly speaking), OPPBTP and INRS. On their websites, you could find very interesting and detailed guidelines regarding many topics you are interested in.

Above the question of supply, I believe you should consider the whole aggregate displacement work. For example in France (in Europe in general), there are few quarries located next to the construction site, then you need a storage zone, which dimension must be calculated and access regulated, usually only to one machine at a time. In smaller countries, such as Israel, you can reach virtually any point of the country within a few hours. Then it might be a better solution both regarding logistics, cost (for storage) and safety to deliver directly on site. In this case, "supplying" infer further operations...

Good luck

Thanks Yoram!