Household Septic System

[jlgurr]

Been seeing a lot of messages about septic systems lately so it appears there are several of you who might have some advice or ideas for my situation.

We live in a house built in 1978 and I have located a copy of the original inspection of the septic system from the local health department. Ironically the inspector is the father of an engineer who I work with. Since we moved in here in 2005 we have had no plumbing problems whatsoever so hopefully I am not going to jinx myself by bringing this up. Just in case there was a problem I'd like to know where the access to the tank is so we started looking for it last year. No I haven't been looking constantly since then, just saying it's been a while since we started. We could not find the tank nor a drain line from the house to the tank.

There is a toilet in the walk-out basement. The ground outside the bathroom wall is within just a few inches of being same as the floor level of the basement.

How much lower than the lowest toilet is the septic tank normally buried? In other words, how deep will I need to dig to find the tank? How far off the sketch is an installer allowed to deviate? Of course, the inspector does not recall my specific installation as I am sure he literally saw thousands of them in his career.

Thanks,
Jeff

 

[Baby Grand]

Our big tank was "burried" so shallow that the cap on the clean-out plug was sticking up through the lawn - about 2' elevation below the first floor & base of the toilet. Since the house was connected to the town's sewer system, many years ago, I dug up the old tanks. They were made of steel mesh reinforced concrete, back in the 50's. If yours are of the same construction, I'll bet a decent metal detector would give you a fair shot at locating them.

 

[dave1949]

The fall in the pipe from the house to the tank should be around 1/8" per foot. If you can find the waste line exit from the house it would really help point you in the direction of the tank.

Good idea to find it now while it's not an emergency.

 

[ThomasH]

How much lower than the lowest toilet is the septic tank normally buried? In other words, how deep will I need to dig to find the tank? How far off the sketch is an installer allowed to deviate? Of course, the inspector does not recall my specific installation as I am sure he literally saw thousands of them in his career.
<snip>

It is typically within 25 of the house. It is typically a foot or two down from the terrain, but that depends on the terrain. I have seen them a half a foot down and others that were six feet down. You should try to locate the pipe exiting the house, and you can probe along that pipe to find the tank assuming that you have a probe four or five feet long. Bully Tools

 

[ddbackhoe]

Without knowing local code? The septic could be anywhere. Starting at a known exit point from the house......The concrete tanks have steel loops on the access ports. A good metal detector is easiest. Depth can vary , but I'd suspect ground level up to 1 foot if it's in the first ten away from the house. Assuming it's a gravity feed system, the farther away from the house, the deeper it would be (~1/8" to 1/4" per 10 feet). When you find the tank and get it open, get the local sucker truck to come empty it (fairly cheap, 250ish here)

 

[ddbackhoe]

It is typically within 25 of the house. It is typically a foot or two down from the terrain, but that depends on the terrain. I have seen them a half a foot down and others that were six feet down. You should try to locate the pipe exiting the house, and you can probe along that pipe to find the tank assuming that you have a probe four or five feet long. Bully Tools

A probe works, good point. Once we go past 9", we add a riser for the cleanout. Pump-ups, pump-outs get a riser anyway to access the chamber.

 

[Paul Thornton]

If you can find out who has pumped the tank in the past they might know. I have both marked mine and measured from two points on the house to identify the covers.

 

[eddie48]

If you can access a cleanout in the house you can run a snake down the pipe until it hits the tank. That may give you distance but, better, if you have someone with good ears outside you may hear it hitting the baffle in the tank.

 

[jlgurr]

The permit indicates a 1500 gallon tank with 15 feet between the house and the long wall of the tank. Apparently the tank is rectangular with its long side parallel to the house. At the far short end of the tank there are 4 field lines 86 feet long and spanning a field ten feet wide (not sure that is important). I have poked with the inspector's probe all over this area and up to 18" deep with nothing. The red clay next to the house is under a deck which I can walk under and is hard as cement from being so dry for so long. I will need to use a mattock to dig for the house drain pipe. At that point I might need to add archaelogist to my name because I'd have to be very slow to prevent striking the drain line.

How tough is the tank? Would a FEL bust it if I was going to slowly scrape away a foot of dirt over the area where the tank "should" be?

 

[jlgurr]

Good idea to find it now while it's not an emergency.

Yep, that's why I started looking already. I remember being a kid and dad paying through the nose for an emergency pump-out and it made a nasty mess in the house.