Wells, Sump Pumps and Septic Sewage Systems - Suggestions on locating septic

I have an older home from the 1940's
The house was enlarged in the late 1990's - foundation was extended 8 feet on three sides.

I have basement floor drains that I do not know where they go.
I also have a newer septic system installed in the 1990's. I can see where this exits through the basement wall.

I cannot find anything outside of the house that would be a tank cover.

I am not sure where to start. Would a septic service be able to find my tank or tanks?

Good morning, This may be the perfect time of year to let mother nature locate it for you. With a frost or light snow on the ground, there is a chance the top of the tank will be visible, no frost. I use a piece of rebar sharpened a bit on one end and bent into an "L" on the other so I can push it into the ground and locate the top of the tank. Soil has to be soft enough to test at least a foot down. It should be about straight out from where you see the pipe exit the basement and the lay of the land should be flat to down hill.

If you are looking for a 1990 system, there should have been a permit pulled and a plan submitted as to where it was supposed to go.

Yes, a pro can find it, but take a look for missing frost, you might get lucky.

Bud

I went to the county and I have a "sketch" on the location. It is not in a direct line with the exit from the basement.

The exit from the basement is a fresh concrete patio that was poured in the 1990's.
There is an access port near the wall of the house were the septic ends.

the septic must make a 90 degree turn, due to the sketch from the county

I made a 4 foot rod, and already probed the entire area.
I have looked for tall grass areas in the heat of the summer... nothing.
I don't even know where the drain field is.

I was told the septic is original 1940's by the old owner. So he just tied into this old tank? Maybe there is no leach field??

I will look for frost now.

I think the old owner graded and leveled dirt over the top of the septic, so it is buried down deep....

Bud9051 is right about letting the snow/frost find it for you UNLESS it is indeed buried deep like you think. If it's too deep then even that trick wont really help you.

Does the sketch from the county indicate any distances from landmarks? Sometimes they may be written on the permit but not necessarily logged on the drawing.

Have you walked along the most probable perimeter of the property and looked for wet areas while running some water? Flushing food grade dye repeatedly down a toilet (the darker the dye the better) and watching for the color to show somewhere downhill of where you think the tanks are is an easy trick. It may take a few days for the dye to work through the septic system to the discharge point but it's a common practice by health inspectors around here when checking for a properly functioning septic system but I have never seen how long it takes to get the color out the other end.

The old permit shows 12 foot out and 6 foot over from the new foundation.
This assumes the new foundation was poured per the sketch.

This is the area I probed. I maybe forced to dig.

I like the dye idea, I would like to see the leach field.

I have no wet spots in my yard due to septic.
Some people even have taller grass.

I think my field may have been buried some also when the property was leveled.