I have a pile of bricks and pavers (left behind from the previous owner). My septic tank is exposed a little in one corner, right at the base of my porch steps. I was thinking of scraping the tank clean then throw the bricks right on that, and then have some overlap onto dirt/sand. Is this advised? I'll make sure the opening is easily accessible. Should I throw a layer of sand down first?
I don't think it's a bad idea, but having a different surface underneath the tank in some parts of the patio and dirt under the rest could cause some problems if you aren't careful.
Start out by preparing the base for the patio. You'll want to dig down a few inches in the surrounding dirt and fill it in with sand. Make sure it's compacted really well - the base for a patio is critical, and since the dirt will settle but the septic tank won't, you need to make sure that most of the settling is done before the bricks go down. You can rent a compactor from tool rental places.
As far as putting sand on top of the septic tank, I think you should put some down as long as you can make the entire surface level without making the sand too deep on any one part. You don't want more than a couple inches of sand.
After the sand is compacted, lay the bricks and compact again. Once everything is set, sweep some polymeric sand into all the cracks between the bricks. This sand will bind the bricks together and keep them from moving too much. After sweeping it in and cleaning off the surface, wet the whole patio down to activate the polymers in the sand.