OK, 1 more post regarding questions for my new shop/yard. We use quite a bit of bulk soil and mulch. Does anyone have specs for bulk bins? 1. I plan on having a concrete floor. How thick is needed to handle a semi backing onto it to offload with a walking trailer floor? 2. I have seen alot of diferent ways to build the sides. As a cost saving measure I thought about using railroad ties and covering the inside with plywood. Has anyone tried this. Any other good ideas that may be cost effective (cheap).