Seems like the easy thing would be to start a
compost pile. Dump all the accumulated humanure buckets and urine together in a pile, cover with some mulch to keep flies away, and leave it. Turn it if you want it to finish quicker. Then when you are planting something permanent, use some of it, kept underground. If you aren't gardening or planting at all, just scatter it in the forest after it's been working for a year or two, while in the meantime you've started a new pile. To be safe for salad crops or root crops you will need to hot-compost it, which is a bit more involved, but for trees, perennials, stuff that will be cooked, just go ahead and use it as is. I've even dumped buckets directly into planting holes for new trees and shrubs. I would avoid dumping all the pee into one place to seep in....it's a waste of powerful fertilizer and you might set up a plume that could eventually reach groundwater. Just incorporate it into the humanure compost or trench it under the surface scattered around stuff that you won't be eating raw. You want roots, organic matter, and topsoil microbes to be able to get at it. Pathogens don't translocate into or through the vascular system of the plants.....they spread in water, on flies, and on hands for the most part. See Jenkins' "Humanure Handbook" for the long detailed overview.