Stopped by daughter's new house today to check on a couple of things and got to looking at the septic system.

The top of the tank is at existing grade and will likely be under 3 to 6 inches of finish fill/loam/grass. Good so far.

The area they have prepped for the leach field is a good 8 feet LOWER than the tank and about 25 to 30 feet away.

That seems like a hell of a drop to me. IIRC, septic lines from the house to the tank are pitched at something like 1/2" in 10 feet, right? I don't know what to expect from the tank to the field.

I guess as long as only liquids exit the tank (as designed) it should be okay, but I don't recall ever seeing one laid out that way.

EDIT: Looked on line and it appears that 1/4" per foot of run is the norm.

Doesn't sound like a problem to me.
I wouldn't worry. The entire system is laid out by the applicable code / inspector and will be inspected before it can be covered up.
At least here it is. Here the controlling agency is the county health dept.

Was the top of the tank exposed, or was there a service entrance. I have a man hole on top of mine slightly below grade so it doesn't have to be dug up for service.

The outlet from my tank is 5 feet below grade about 2/3 up from the bottom of the tank.

When you say prepared the leech field, do you mean rough grade. The in situ soil conditions could be such that you have to place a lot of gravel under the pipe to drain the water away. If the top of the piping is that low I'd question it.

The plans should be on site for the inspector. I assume this is being built by a licenced contractor and will be inspected prior to covering it up.

This looks like a pretty good reference for you www.eco-nomic.com. The tanks should have enough cover to support grass growth...3"-6" not going to work. I would want to see more like a foot or two. Mistakes a lot of people do is hiring an "expert" to do the install without a set of plans and specs. I have seen contractors who "have been doing it this way for 30 years" that are dead wrong. That's why plans and specs exist to cover the owner and to guide the contractor.

Given the code inspections mandatory in the town she is building in, I'm sure it was designed by a pro and will be inspected before it's covered.

Without cracking open my old text books and looking up the details for Maine (where, IIRC, it gets damned cold), the design sounds correct.

In your region, you need to have at least four feet of cover overlaying the leach field piping. Just like you need to dig down four or more feet for a foundation.

Then below the piping there is another three or so feet of porous media that allows the effluent room to percolate downward while making good contact with the biofilm that provides a large part of the treatment for the organic content of the effluent.

quote:

The area they have prepped for the leach field is a good 8 feet LOWER than the tank and about 25 to 30 feet away.

You have to break what they call the crusty layer for the water to drain.

When my lot in Loudoun County was perked, they had to go down seven feet to break the crusty layer. Then they will back fill it with about four feet of gravel before laying the drain pipe.

I wish mine were gravity feed. I just had to replace a pump. 'Twas not cheap.

I am in NW Ohio. All sand. Put my own septic system in 21 yrs ago. My tank only has 1 ft of dirt over it. 900 linier ft of leach field running flat( no fall). Don't want all the water running to the end. Had to have at least 6in of cover but no more than 18" over the leach pipe. I put more stone under mine than required. Pipe had to be covered with #6 washed stone and then a layer of straw to form an organic barrier so sand would not was down into the stone.