There's a show that's shown on the science and/or travel chanell sometimes called Mega Shredders. Those are probably the ones you should be using. I would think you'd need an occupatiental license to show you're a business and some certificates showing you'll be responsible should anything be leaked into the groundwater. A couple of yards around Sioux City bury a tarp a foot down to prevent any kind of leakage and if there is, it'll collect in the tarp and not get into ground water. Other then that, pick your location and get workin. Contacts come by word of mouth alot - I don't think there's any sure-fine way of attracting large clientel(I mean, if i'm xyz corp and send my stuff to yard ab, why should I send my stuff to you instead of my regular yard).