The PDF enclosed is from Home Heating with Coal, a book by Steve Sherman which appears to be out of print.
Also, here is a description of building a coal bin submitted by Ken Rajesky
Building a Coal Bin:
This particular drawing is for a two-ton bin, but reduced proportionately, you can get the idea of design & construction. The material used is 1/2 to 3/4 plywood, and 2 x 4 boards. Leaving a channel on one end to remove the end panel for cleaning isnt a bad idea either. For a 2 ton size, the specs. call for a length of 97.5, width: 62, height: 28.
For a 1/2 ton size with room to shovel and clean, I would go 36 in length, 24 width, and keep the height at 28. You may disagree thinking its too large, but better to be a little more than not enough.
Youll need (2) 4x8 sheets of plywood, (3) 2x4s, (4) 2x2 balusters, and screws.
I would lay (4) 24 2x4s down on the floor, one on each end, and the remaining two spaced 11 apart. Screw the bottom of vertical 2x4s (28 high) into the horizontal 2x4s.
Cut your plywood sides & ends, and screw the sides to the vertical 2x4s. Then, cap the end with screws, overlapping the end 2x4s. At the other end, buy (4) 2x2 balusters used for deck railings. Cut them at 28 high.
Drill pilot holes, and screw one at each end (at the open end side) into the plywood & 2x4.
Now, measure a space a little wider than the plywood you are using, and screw in the other two 2x2s. This now forms a channel so that the last remaining plywood end will slide into to allow to you remove for cleaning. If your storage area is damp, a little application of Thompsons waterproofing is helpful for long term durability.