Urgent Question: is it ok leaving HPB in raining?

Recommendation based on experience with HPB (i also used 20 tonnes) - put down a large tarp or two on the entire area where you will be having the stone delivered/dumped, makes it much easier to manage and clean up once you're done.

Other then that, no issues with it getting wet. HPB is clear (the fines/crush dust is washed away) 1/4 chip stone

Thanks jacquesstrap, very helpful, will buy the tarp today, and I don't have to call them to reschedule delivery with no worry about rain.

and another question, anybody have idea about how weight of HPB per cu yard? I had asked few company, most of them said 1.6 ton/cu yard, but dufferin aggregate (I ordered from here) said 1.2 ton/ cu yard, they all sell by weight and confused my calculation.