You do want to use a machine with lots of water so that any colour bleeds go into the water where it is picked up by the colour catchers. I think I woyld test my intense colour scraps first to see how they bleed. You put some scraps in hot water in the sink and then lay them on a white paper towel to dry. Is there any colour in the water? Is there any colour transfer on the dry paper towel? That will tell you how bad they will bleed. Maybe you will be lucky and they will be good.
If the scraps bleed a lot you may want to look into synthrapol from your local quilt shop before washing. Synthrapol is added to the washer and it suspends loose dye in the water and prevents it from going on to other fabrics. Most important!!!If you wash and finds some bleed spots, do not dry it because that will set the bleeds.