Have a weird Septic issue

[lzicc]

I bought this house last year. It had a septic tank with a leach field. Years ago, city sewage was installed uphill, so the pump that pumped to the leach field now pumps to the city drain. We had some bad rains from the last hurricane, I live in pa, and during this time, I flushed the basement toilet and the water did not go down.

After some troubleshooting, I pulled the lid off of the septic tank and it was full to the top with water. I pumped it out with a sump before it backed up into my basement. I went up to the manhole where it pumps to and it is pumping water, just not fast enough. The manhole is quite a bit higher than my tank. If I would have to guess, the elevation difference is a good 20' or more and from the distance from the tank to the manhole is about 300', so it is a long distance.

Since the rain subsided, the issue seems to have gone away, but how could rainwater get into the tank? The lid on top is plastic and screws into the tank. That pretty much seals the top of the tank. Also, there is no rain water that goes over top of the lid when it was raining. The only thing I can think of is that the houses gutters routed into the septic system? I did flush some red dye into one of the downspouts, but didn't see it in the tank.

I think the pump can deal with daily house drains, but it got overwhelmed with the rain. I also only have 1 septic tank lid, so I am assuming that there is only one tank unless the other lid was covered up.

Moving forward, I am going to replace the tank with a fiberglass simplex tank and a 2 HP Grinder pump, but for now, I would like to hold off on that.

 

[oosik]

Well - lets assume the pump is working and that the excess water is rain water. Being an old septic tank - it has an inlet - that you are currently using - - an outlet that you may or may not be using, two inspection ports on the top of the tank and some way for the pipe from the pump to get out of the tank. I count - at least - four openings that could be leaking. Inlet - outlet & two inspection ports.

Good move to get away from the old septic tank. For that matter your old septic tank could be a split tank - top half & bottom half - bonded in the middle with a product called Ram-Neck. The Ram-Neck seal could be leaking and letting water into the old septic tank.

 

[lzicc]

I see the inlet pipe, there is a clean out between the house and the tank and when water is running inside the house, I can hear it enter the tank. On the opposite side of the tank, there is a 1 1/2" pipe that runs to inside and elbows down to the pump. Where the leach field was, a housing plan was built many years ago. The prior owners sold that part of the land to the development, in exchange, the developer woul set them up on the city sewage system, so I wouldn't think anything of the old pipes that go to the leach field would still be intact for it to back flow from.

 

[wagne223]

You or a pro need to make sure the outlet from the tank to the leach field has been capped.
Most systems do not have a check valve in that line and a saturated ground will drain back into the tank.

The next thing to check is where that pump discharge pipe breaches the tank. It should be sealed also.

You could also have a failing or clogged pump.

With your setup, the septic tank is just a basin and should only have a few inches of water in it.

 

[RNeumann]

If the leach field was abandoned but still hooked to the tank the only thing that would need to fail is the check valve between the tank and the leach field. Ditto for the check valve between the tank and the City sewer. They routinely fail. When they fail the pump usually is t far behind because it’s running way too much.

If I’m reading the post correctly the tank is 20’ deep. If that’s the case have fun replacing the tank.....hope u have lots of room for dirt!

 

[wagne223]

If the leach field was abandoned but still hooked to the tank the only thing that would need to fail is the check valve between the tank and the leach field. Ditto for the check valve between the tank and the City sewer. They routinely fail. When they fail the pump usually is t far behind because it’s running way too much.

If I’m reading the post correctly the tank is 20’ deep. If that’s the case have fun replacing the tank.....hope u have lots of room for dirt!

I think what he means is there is a 20' rise from his property to the sewer line. Like he is down a hill.

 

[Oldoak]

I think what he means is there is a 20' rise from his property to the sewer line. Like he is down a hill.

Yep, that's the way I took it.

 

[WVBill]

.....so the pump that pumped to the leach field now pumps to the city drain. .

So the original leach field was above the septic tank?? That seems quite unique since a leach field depends on gravity to drain the effluent through the soil. I would also say it's the most likely source of rainwater back flowing into the tank now. As others have said your first step should be to ensure that whatever pipe used to carry the effluent from the tank to the leach field is now sealed.

 

[oosik]

Nothing unusual about there being a great distance between the septic tank and the drain field. My septic tank & pump tank is near the house - the pressure drain field is 275 feet away.

I was Director of Environmental Health in Anchorage, Ak for 18 years. 1964(the good times) to 1982(the good times to leave). Occasionally we would have a situation such as IZICC has here. Being, the public sewer was higher than the houses it served. We NEVER allowed any part of the old septic system to be used when the house connected to public sewer.

It was always a new collection/mixing tank and a grinding/lift pump. Just way too many old problems can carry over when components of an old system are connected to a new collection/disposal system.

 

[quicksandfarmer]

It it possible the drain for the bathroom exits the house on a different pipe from the rest of the plumbing? That's pretty common if the bathroom was added later. If so, is it possible that when the system was switched over to public sewer the basement got skipped?