Septic tank missing T and badly angled main line?

denemante · 11-21-2011, 02:04 PM

Hey all,

The septic saga improves yet continues...

I just had my tank emptied. I think some solutions were learned regarding my year-old post here: septic emergency? help!

They dug and pulled both caps. The tank level was correct.

My 1500 gallon tank has two chambers. In the middle wall, there is a horizontal slot about halfway up. The far end of the tank (where water leaves and enters the fields) had a PVC "T" - although it was more like an L pointing down. There was a filter in it which was good, although they hosed it out. That chamber was full of water.

On the end where waste enters the tank - the tank was full of solids, which they pumped. They said levels were normal.

However the "T" (or downward pointing L) was missing! We figured it fell into the tank.

So it was just an 8-inch PVC pipe laying horizontally dumping into the tank. It comes about 3-4 inches into the tank. The solids were just reaching it, so the very bottom of this PVC pipe was about 1/2 inch or so in the solids.

We ran water inside the house (flushed basement toilet and left basement sink running), and all sorts of nasty stuff came out of that pipe into the open septic tank.

So it seemed obvious that waste has been sitting in that line until enough comes behind it to push it into the tank.

After just a moment, it appear that waste has all been pushed into the septic tank. Soon a steady, light stream of clear water was running out into the tank - again - level with the top of the solids. So the clear water was really sort of running out onto the top of the solids.

We have a clean out opening in the patio 15 feet away from the tank. The guy told me that while the T should have been on there in the tank, the line running from that clean out area to the tank has likely been comprimised. The previous owner had grading, the patio, etc. done. That probably pushed down on that pipe. There is a elbow in it somewhere where it turns to enter the tank. So some point in that line is too low, and thus water can't run uphill (and worse, septic stuff flows from the tank back into the main). He suggested we cut and dig out out the patio and replace that line, this time assuring it has a downward slope ($1800-$2600).

I opted not to have them do this today.

Worth noting - I called these guys finally because nasty stuff came out our basement shower drain the other day. Just a little, but it was there. This was when my wife was doing laundry. So it would seem that for whatever reason, stuff couldn't drain into the tank that day and took the path of least resistance out the shower drain.

(I've since left that patio clean out open which presumably will allow any future overflow to exit there vs. my basement bathroom).

Strangely, one year ago - the toilets in the rest of my home (even upstairs) all refused to flush. Since the basement bathroom didn't see backup, there must have been a clog in the main before the basement drain that worked itself free.

It does seem to make sense. Without the T, solids/water would back up into the main. That was coupled with a bad slope on that main, allowing stuff coming from inside the house to further fill that main drain. Probably moreso even during times of heavy water use.

They pumped the tank - all good - and we expected to find the missing T in that solids chamber. But it wasn't there.

So all this time - it's been missing. I can't understand how that could be.
We've lived here two years and never had any septic work done. No one would have only pumped from the other side (the water chamber) and missed it. I thought maybe they had and that's how any previous pumping company missed the fact that the T was missing.

I mentioned in another post - the previous owner had an enitrely new (2X size) drain field installed in 2008. I was told they did that because they added a basement bathroom. Whatever the reason, how could a field installer not have noticed the missing T?

So - the guy today installed a T on the side that dumps into the tank to replace the missing one.

I did watch as water did flow into the tank - although sort of slow (but perhaps that's normal). I mean, should all waste 100% exit the home immediately and enter the tank, or is it at all normal to have some left in the main until more pushes it out? Perhaps we never have a problem with greywater - perhaps my problems are when there are mutiple, close sequential flushes of toilet paper which then clog the main (at the low point) temporarily outside the tank - and showers or wash then blow it through (the guy today said I could try double flushing).

So I wonder if I really do need to dig up that section prior to the tank and install one on a better slope (as he suggests). Or perhaps the missing T was my only problem.

Thanks for sticking with me as the saga improves yet continues...

teststrips · 11-21-2011, 03:59 PM

I guess I'm missing how you would change the slope of the pipe. You have two fixed points - where it comes out of the house and where it enters the septic tank. Unless one of those points are changing, the slope should stay the same. I suppose if things weren't installed well with a proper base under the pipe to keep it from moving, you might have a section heaved up in the middle, but that shouldn't really matter - gravity still works and it'll eventually get pushed out. The only way that slight slope changes in the line would matter is if the pipe broke/cracked when the ground moved. Only way to know this is to have someone send a camera down your line. While they are there, have them check your vents lines too... the gurgle noises and air bubbles mentioned in the other thread still make me think venting might be an issue on your downstairs toilet.

As far as work done recently - missing the T on one input side of the septic tank can really cause problems. Without the T "baffle", the thin crust that normally forms on top of the tank would cause issues letting new sewage into your system. At this point, let the tank fill back up and see if your issues are gone (it took my family 3 days to fill my tank back up to its normal level after having it pumped). If things are good in 2 weeks - just keep to normal best practices for a system with a septic tank - go easy on bacteria killing products (bleach, cleaning supplies, shampoos, soap), and add septic maintaining products (such a bacteria cakes) at recommended time intervals. Get the tank pumped following this formula (5 years minus 1/2 the # of people in your house). (Example 6 people = 5 years - 3 = pump every 2 years.) If you have more than 8 people in your home, I'd suggest a yearly pumping.

If your issues come back in a few weeks - have someone with a camera come out and investigate venting and cracks.

denemante · 11-21-2011, 05:54 PM

Actually, the main line in question (running from under my home slab out to the tank - it has to have a right angle in it as it enters the tank perpendicular from the back of the house. As you look at the 8 inch part sticking out into the inside of the septic tank - it actually looks like it's pointing up just slightly - as is the side under the dirt just beyond has been pushed down. I agree - if it were a straight pipe it would be hard to flex. I think (if what the guy said is true) - it's dipped at the elbow from the weight of dirt, grading and cement put in after it. Very nearby, my deck footers had sunk a few inches. I fixed that.

I have no idea what the last guy did (or what the people he hired did) before I owned the house. But it just seems very, very suspicious that the T would be missing. Almost like it was removed purposefully. Why else would it be missing?

Perhaps it was removed purposefully to ease the flow into the tank from the poorly sloped main.

So at least in the 2 years I've lived here - the septic has mostly worked just fine without the T. Apparently, the open end just poured into the tank just at/above the normal solids level.

NOW - with the T installed, the sewage is pointed down toward the bottom of the tank and will escape that T in the liquids layer.

If I fact I have a slope problem on my main just prior to it entering the tank - whoa - then wouldn't it be even harder for gravity to push waste into the tank?

LateralConcepts · 11-22-2011, 10:29 AM

It sounds as though there's a belly (low spot) in the line between the house and the tank. You should have the line video inspected. Otherwise, everything you've mentioned is merely speculation.

A low spot in the line will slow the flow of liquids and solids. Water will slowly purge through, but leave solids behind eventually causing a soft blockage. That's when a large volume of water; i.e. doing laundry, overwhelm the lateral.