[chandler48]

Just create a liftable panel in your decking which, when removed, will give you access to the clean out. Raising the dirt on the wall will present water problems in the crawl space if you don't apply really good waterproofing prior to backfill. So make sure that is done. The clean out is incidental and can be anywhere along the line, BUT it is always better to have it close to the house for operational ease.

 

[chandler48]

The septic tank most likely will have two sections. One inlet where the solids and liquid enter, with a baffle from the top to just short of the bottom. The decomposition takes place here and nothing but liquid goes under the baffle and out into the drain field. Yes, having it pumped (every 5 years or so) can be expensive to dig down to the tank, remove the caps and pump it. Not sure what your tastes are, but if you install risers on the tank and a cap, the cost of pumping can go down drastically, since they don't have to "find" it and dig down each time. The caps can be about grade level and become part of the yard easy enough. No digging in the drain field area. Check with your health department. They will have a drawing of your house with the septic system and drain field for reference.