Single File

At my job, I have begun to take on more tasks. I feel bad because I do not have the time to assist in accounts payable anymore which concerns me because I help out two of my co-workers when I do this and I do not want to leave them with mounds of work. But since the RTP (Regional Transportation Plan) files have become my responsibility, my boss feels the need for some reorganization. What is happening is the files contain all of the forms, budget requests, accounting information, previous MAG billing statements, invoices, and so on. Though some projects may last only three years, we are beginning to see a problem with some projects which may last up to ten years. One of the project which deals with Greenfield and Baseline is my biggest worry because the previous MAG billing statement alone was at least 150 pages, and for this go around, the MAG billing statement was well over 250 pages. As many of you know, file folders can only hold so much. With auditors always coming and the need to pull previous information, we are brain storming to figure out a way to properly store the information so it will be easy to locate. I was thinking banker boxes would be key, but I do not know if this would be more efficient than just adding more file folders in the file cabinet. So for instance, we would have two file folders for Greenfield and Baseline. Oh, what to do? What to do? I just want to make sure that for the next intern which comes in, they will not have a hard time navigating through the folders.