Up in Maine the inspectors are real tough. They won't pass you to move forward with your bed if you grade it up with a dozer after you dig it out, they have to see that you scarified it with your teeth. They will fail you if you track any clay or loam onto the sand if you doing one that needs screened cource sand for fill under the stone. Same deal with the stone, we almost always dig all the materials out of the dump trucks to avoid this. When I started in the biz I worked for my uncle, we had a PC150 komatsu and it worked very well, but when I started working for a larger company I started running the 200 size machines with the clean up buckets and found it made for a lot less hand work. thanks for the post, could you explain the Mass rules a little, we have to have an inspection when we stake out the bed, after we dig out and scarifey, and again before we put the fabric over the stone and finish up.
In mass, in the towns I work in anyway- you get an inspection when you finish excavating the leaching area, one upon completion. An engineer has to shoot in the final grades and locations before you backfill. We have the same strict standards for stone as well as sand. One town will actually make you turn in your slips for gravel to prove it came from the same pit your sieve analysis came from.
Inspections vary from town to town but some of the inspectors want 'eyes on' the stone under your septic tank, want to put a level on each length of pipe in the field, want a 6" reinforced concrete pad under your H20 Dbox. Some towns want to do a white bucket test on your stone. Each inspector is different. Some insist on speed levelers and some forbid them.
Ive installed systems in Maine, and found for the most part the regs are very similar....though I found using straw hay in lieu of peastone or fabric a little odd.
Ive also installed a system in Tennessee, and I understand why you prefer the backhoe to an excavator, as you install 150' of trench with a continuous plastic corrugated pipe, through the woods, over hill and dale.
I think for the most part, as Jim said a 20 ton excavator that you can deliver and recover yourself with a dump truck and tag trailer is a good way to go. I have 2 20 ton machines with 5 foot clean up/ grading buckets that work very well. Both can lift a 1000 g tank, and a 1500 in sections when necessary.
YMMV