A scale house is usually just a small, simple building with a door, and a large-ish window overlooking the scale itself. They can also be much larger - one of the scales at the steel plant where I worked had a changehouse, timeclock area, plant security offices, and a small repair facility included in a large, brick structure. For your ADM plant, you could build a small (8'x10' would be a good minimum size) scalehouse from .060" sheet styrene - Tichy has doors and windows that would be suitable - then paint it like concrete to match the main building. You could also build it from styrene siding material or brick sheet.
The scale itself is usually just a flat area in front of the large window, large enough to accommodate the longest trucks that you plan to use. The one that I mentioned above had the both scale platform and pit edged with steel angles, then pavement over the balance - the whole scale was flush with the surrounding road area. Some scales are also elevated a few feet above the surrounding ground, with a suitable ramp at both ends - the gap around the scale platform is only an inch or so, and the deck is always closed so that no debris can fall into the pit. Some decks are made with heavy diamond- or checkerplate steel. Don't forget to add "Stop", "Proceed", and "Back-up" lights where the truck drivers can see them, along with appropriate signs.
Wayne
