Have a weird Septic issue

[Lonny18]

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.

Sounds to me like you could have a crack in your tank somewhere or the mastic that seals your risers to your tank are leaking and allowing ground water to enter the system when the water table is high. This is a more common problem than you would think but most never realize that it is happening. No real way to fix it unless you dig up the tank and replace it. Seeing as how you are now dumping into city sewer you should no longer need a tank at all you should be able to get by with a small sump basket in the basement with a grinder pump. This all assuming that your current pump is working properly I don稚 know how old your pump is but life span around here is typically 5-10 years

 

[lzicc]

Lonny18, you are correct. I will replace it with a fiberglass basin and a grinder pump, but first I have to figure out why the tank is not draining with the pump running. There is either a clog in the discharge pipe or and a break.

I am starting to think that the rain is coincidental now. Yesterday, it rained all day. when I got home from work, I put my sump in the tank to drain it down so it did not back flow into the house. Once the tank was about halfway emptied, I could hear water running into it. There was no water running in the house, so I assumed it was the rain/gutters. I went back out an hour or so later and could not hear the water running anymore, but it was still raining. I am starting to think that there is another tank underground that I cannot see. I'm thinking that both tanks fill up and when I empty the tank that I have access to, the other tank is draining water back into the tank I am draining. So the tank I cannot see is the main tank and the one that i have access to is the greywater tank. It would make sense why I would hear water running. Or it could be 1 big tank with a baffle in it to keep the solids contained to one side.

I still have the issue of it not pumping to the manhole that I need to address, but that would make sense. There should be 2 tanks in a septic system. I'm going to have to start digging around the tank and see what I can find.

 

[CADplans]

The tank needs to be graded like a water well,,
surface water needs to be directed away from the septic tank area.

We purchased our house, then a couple years later, there was an eight inch rain storm
the clogged gutters overflowed, the water came through the basement walls, and into the basement.
I learned my lesson, clean gutters, and proper grading,, no more water in the basement.

The water is coming from somewhere,, stop the water from getting to the tank area,

 

[lzicc]

The top of the tank is graded away so water can't get in. I think the issue is that the pump is running, but the pipe that feeds to the manhole is either clogged or broke. So after after some time, the household waste is filling up the tank and the pump is trying to pump it down, but somewhere there is a clog or break in the pipe.

 

[Lonny18]

When you replaced your pump did you check the size? In order to pump that kind of distance with that much head you will require a rather large pump. The gpm they put on those pumps are rather deceiving because they are typically with little or no elevation rise. We just put a septic system in a couple of weeks ago that required a $900 pump because of the pressure needed to pump that kind of distance. That was 2 x the price of the typical pump we use. And you are correct on your tank. You should have around 4 risers on your tank. One inspection pipe for the pipe coming from the house ,one inspection pipe next to the wall in the tank on the solids side ,one inspection pipe on th other side of the wall on the water side and then your pump riser.

 

[lzicc]

The pump that I pulled out was working. I replaced it with the same spec one just thinking that the old pump was wearing down thinking that was the issue. The pump I replaced it with was $600. I got it wholesale from a place my wife used to work. It was spec'd out for my application. When I replace the system with a grinder pump and new tank, I'll be around $4100 for everything. It's a 2 HP with and alarm, multiple floats, guide rail for the pump, etc. Goulds makes it. Before I do that though, I want to see what is keeping the current pump from pumping.

 

[RNeumann]

Does the current pump, hooked to your sump pump hose keep up? How or why would you install a pump for raw sewage that doesn’t have a grinder? From my first question I’m sure you are gathering I’m thinking it’s the “new” pump. I’d also try the sump pump hooked to the existing sewer line.

I was also thinking it would be near impossible (I’ve never seen it) to plug a pumped DWV line with ground affluent. But I’ve also never seen someone try to pump raw affluent with a non grinding pump.......

 

[goeduck]

You are correct sir, I confused myself.

Been happening a lot lately.......

At least you did not call it a diode.

 

[lzicc]

The pump that is in there is a sewage pump that will pump up to 3/4" solids. When I drop my sump in to empty it out, it is just a regular sump and I'm pumping it out at level ground and it pumps it down halfway in about an hour or so. It's pretty fast, but again, it is not pushing up hill. I thought about connecting that pump to the discharge line, but I doubt it would be strong enough to pump up the line due to the elevation.

Does the current pump, hooked to your sump pump hose keep up? How or why would you install a pump for raw sewage that doesn’t have a grinder? From my first question I’m sure you are gathering I’m thinking it’s the “new” pump. I’d also try the sump pump hooked to the existing sewer line.

I was also thinking it would be near impossible (I’ve never seen it) to plug a pumped DWV line with ground affluent. But I’ve also never seen someone try to pump raw affluent with a non grinding pump.......

 

[lzicc]

I talked to the sewage authority and they cannot snake back to me since it is considered private. He did say that there may be a second check valve up closer to the manhole. That could possibly have clogged or is stay shut.