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?

 

[CADplans]

My basement stairs have a floor drain in the center,,
that drain is connected to the septic tank.

When the gutter is clogged, the gutter overflow goes down the steps, into the drain, into the septic tank,,,

make sure your gutters are not clogged, diverting water to the septic tank somehow,,,

 

[4get gto]

Maybe your tank is getting water in from a crack or something. Mine does when we get a lot of rain and the ground can't take it away fast or fully saturated.

 

[Tractor Seabee]

300' of 1.5" pipe is a long stretch unless the pump can get the pressure up to the GPM required to efficiently empty the holding tank (old septic tank). The 20' + elevation plus the depth of the tank bottom (probably at least another 10") adds a lot of static head to the friction head. Is the pump the old one (grinders can wear out also) to the leach field or a new grinder type? What type pipe is the pressure main? Iron pipe has a high friction factor over PVC or ABS. It doesn't take much debris to partially plug that size line . Stuff can really hang up in a check valve and elbows, then the line drains back to the holding tank every cycle. Where does the pressure line enter the city manhole? An open check valve could siphon stuff from up there also.

Other posts have provided some good check points also.

These things are not always simple.

Ron

 

[Snaker]

I'm not really getting this whole thread. OP says switched to city sewer by redirecting the leach field output?
That is liquid's only so do you still have to call in a pumper truck occasionally to remove the solid's? That would be somewhat of a foolish design.
If it was a complete sewage reroute then I would think the tank would have been replaced with some sort of a transfer tank.
Otherwise you have a real jury rigged mess there.

 

[RNeumann]

I'm not really getting this whole thread. OP says switched to city sewer by redirecting the leach field output?
That is liquid's only so do you still have to call in a pumper truck occasionally to remove the solid's? That would be somewhat of a foolish design.
If it was a complete sewage reroute then I would think the tank would have been replaced with some sort of a transfer tank.
Otherwise you have a real jury rigged mess there.

It’s a bit confusing and I think the OP is a bit confused too. If you have a leach field that is above the septic tank you would go out of the tank and into a pump pit/well and from their it pumps to the leach field. If the septic tank is higher than the lowest plumbing drain the pump pit would be how the septic tank is fed. It sounds like he pulled the lid to the pump pit and found it full and the pump failing. OP called this pit his septic tank but also said it had only one lid- further reinforcing my theory. A new pump and check valve are probably in order. If it wasn’t pumping at all the first check is the float switch.
On commercial or public systems they typically run two pumps and have a maintenance program that sees routine inspection and prophylactic replacement of pumps, float switches etc.
It also sounds like the plumber did his basement correctly by installing a check valve in the sewer line- this would make for a toilet that “won’t flush” instead of a toilet that is sending affluent into the basement......nothing like a poo geyser coming out of the basement DWV!

 

[Snaker]

My mound system has gravity feed from the basement to a 2 stage septic tank.
Solids and liquids go into first stage. A baffle wall in the center blocks solids and pass's liquid's to the second stage.
A pump with a float switch ($600 plus worth) is in the second stage and pumps out of the tank and up hill to the mound system.

 

[plowhog]

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.

If you are going to do this anyway, I'd consider speeding up the schedule. This seems to be a final solution (hopefully?) Why chase other problems if making this change will fix it?

 

[jfh28]

the problem may not be on your end.......there is the possibility that the city's pipes allow ground water into them and if you do not have a backflow valve installed between your tank and the city's pipe then all that excess water in the city's pipe will come down to you since you are the low point.......you can ask the city sewer authority if they have a sudden increase in volume on your streets line every time it rains.......that will be the clue that either their pipe leaks or others up in the line are dumping rainwater into the system........1 1/2" line seems awfully small for a main discharge so I'm guessing your pump is undersized too........if you're going to be replacing everything then don't guess at the sizing.....make sure you get someone who knows how to run the calculations or hire an engineer.......this is to expensive to have to do twice..........Jack

 

[John Fitzgerald]

Sorry for your problems. I would never buy a place that is lower than the sewer, but that's just me. There is too much chance for backups due to city infiltration, pump failures, power outages. For me, that would be a signal to run away from that deal. Sewers should be gravity flow if at all possible.

I hope you can get the problem corrected soon.

 

[lzicc]

To confirm, the city sewage is uphill from the tank maybe about 20'. This is common around here since the city sewage happens to be available at a higher elevation. The leach field was elevated also. It hasn't rained for about week now. I've been checking the tank and it is filling up again. I can hear the pump running, but I am wondering if the pipe that goes to the city sewage may be either blocked or broke. The pump ran all night and the tank level did not go down. BTW, I did replace the pump with a new one when this all started. I am going to try to snake the 1 1/2" line to see how far I can get. What would be a good way to find out the exact elevation different of the septic tank and the city sewage manhole? I'm guessing at 20'. I would like to get a better idea. I found an Iphone app, but it was flaky.