I decided to dig up the outlet line from the septic tank leading to the drain field to install a “T” fitting. What I found was the outlet pipe not even CONNECTED to the outlet of the tank!! This systtem was installed 25 yrs ago.
The outlet of the tank and the drain line is displaced about 4″ verticaly. It seems the contractor just pushed the expanded end of the DWV pipe into the tank outlet and left it like that. I can attach some photos, if that would help (and I can figure it out).
He didn’t backfill with gravel or sand either, but with the clay/rock combination that came out of the ground. Add to that the 20″ depth of the pipe and the thin wall didn’t have a chance. The 4″ diameter has been reduced to maybe 1″ tall and there are many cracks. Obviously gray water has been leaking into the ground long before it gets to the drain field.
I’m still digging to expose the pipe as it obviously needs to be fixed. I also plan on backfilling with gravel/sand and I’m thinking Sch 40 would be the way to go so it doesn’t happen again.
I welcome any thoughts/ suggestions you may have on this.
My new nickname will be “digger” for awhile . . . .
Replies
Pictures are always good to have along with a post. BEFORE and AFTER the fix makes for better "press".
Curious, what grade is the original 4" line that got crushed/disconnected?
What made you dig it up inthe first place? Overflowing main tank?
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
Before's have been posted.
Thin-wall DWV
See first line of my original post "I wanted to install a T"
Hey Digger,
A similar story. Been in a 15 year old house a couple of years and were always backing up the basement floor drain.. Had the S. tank pumped. It was clean but found the outlet would not take water. I too started digging by hand and found a big old rock about 5 feet from the outlet 2 feet down. It had crushed the 4" drain about flat and spit it open. Sandy soil was taking it as besHad to be done on purpose. The moral is always be nice to your help. Too many ways to sabatoge things.
Years later DW cooked up a BBQ hot dog, potato salad lunch for the guys putting in a new water line. Not the reason, she was just being nice, but a lot better chance that line got bedded properly.
I've seen this happen a few times. Bad installation. Failure to properly connect the outlet pipe to the tank, plus using too fragile pipe to bridge the space between the tank and undisturbed soil, plus poor backfill.
You don't say how far it is between the septic tank and the distribution box (I'm making an assumption that the system has a distribution box), but you may be best off to uncover the whole run and replace the entire pipe. Schedule 40 is definitely the way to go for both the outlet tee and the pipe between the tank and the d-box.
Even if you don't need to uncover the d-box to replace the pipe, it's not a bad idea to check the condition of the d-box. The missing outlet tee may have allowed solids to flow from the tank to the d-box (depending on how long the pipe was more or less intact), and the d-box may need cleaning. It will also allow you to get some idea if the pipes leaving the distribution box may need work.
I'd like to see some pictures.
I worked on it today for about 6 hours. Still haven't completely uncovered the pipe. However I'm now into a sand bed where the pipe is buried and the clay/rock layer has thinned to about a foot, making the going MUCH easier.Interestingly after about 6' downstream of the tank, there are no more cracks/splits/etc in the 4" dwv. I noticed a "mound" just downstream of a "belly". It's obvious they didn't level the trench, not did they use sand for backfill during the first 10' from the tank leading to the drain field. Did they run out? Don't know. But where sand covers the pipe below & above, where it was backfilled, the pipe is fine. I have yet to reach the d-box, so I'm not sure of the distance yet. However, I stuck some small 5/8" dia rigid plastic tubing, like that used in drip systems, through one of the splits in the pipe and kept pushing it in until it stopped. Then I pulled it out and measured it. I'm guessing the distance between the tank and the d-box to be around 20'. Also, the drain pipe never was connected to the tank. There's no connector anywhere. Looks like it was just layed in there. The inlet pipe to the tank DOES have a connector on it. I've already fixed that end (a tree root grew around the 4" thin-wall on that end and crushed it like a nut. That fix was several years ago.)The rental Hilti demo hammer is a godsend. What a great tool! I'm using it with a 4" or so wide spade bit (looks like a little shovel) and it just powers through all the clay/rock stuff. I'll never attack that stuff again with just a pick axe & shovel, it's darn near useless.I took more photos and will post them tomorrow. It's midnight now, I haven't eaten and I'm beat . . . . .
Your story surprises me - not a bit!
First of all, over time things MOVE. In my neighborhood (built circa 1940), there's not a single original sewer line that doesn't have some backslope. You can be sure the lines were straight when they were laid, but time, settling, tree roots, etc., have had plenty of time to work their havoc.
Then there are the practical considerations. Just where is the dirt you removed supposed to go? "Back in the hole" is by far the easiest solution.
Finally, expedience. Here is where compaction gets skipped - or a half-way attempt (like driving over it a few times) is made. You want to try lifting a thumper into a ditch?
While it's easy to look back and say "for shame!,' remember that standards have changed, materials have changed ... and that EVERYTHING will wear out eventually.
A lousy installation is a lousy installation, period. No ifs ands or butts.When they dug the drain field, they removed all that clay & rock and backfilled with pebbles/sand. I've gotten into that section, much easier digging there. Thumper in a ditch? What?Materials have changed? Sand is older than dirt, that's what I'll be using for backfill. It was a lousy job, not done right from the get go. This is yet another thing I've had to fix in a long list of items the so called "custom builder" didn't do right. Furthermore, I'm not alone. He's built several houses in this area and we've compared notes on what he forgot, hooked up wrong, denied, etc."Too much hat, too little cattle . . . "
A 'thumper' is a machine used by a man to compact the ground. Proper practice is to lay no more than 6" of fill ... be the fill sand, gravel, whatever ... compact it, lay another 6", etc. This reduces problems caused by later settling. The machine is a bit heavy, and working with one is definitely an art ... but if you want your connections to remain well supported, skip this step at your own peril. Whay isn't it done more often? Perhaps because construction work typically has a one year guarantee ... and this is one problem that won't show until that period has passed.
On our last house the owner cast a concrete diverter on the downside of the septic tank. So the 4" line went into the concrete and three 4" lines came out of it. But the black water from the septic tank had completely disolved the concrete he had so carefully formed. All four pipes were sitting in ooz.
The water had backed up for about fifty years so the tank was always overly full, had cracked apart and collapsed on one side, and roots were in it. For 50 years it was like that. Until we moved in and started using water like most people do.
I have to admit that this almost happened to me. After a long, hard, hot day of laying pipe, shoveling drain rock, paying for machine time, etc... I let myself get a bit rushed with backfilling around the tank. It was only a few weeks later when I dug it up to tie in a RV dump that I noticed the outlet pipe was badly stressed. Luckily, a bit more hand-digging was all it took to correct it.
I wish you well with your fixin'
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Here's some photos:
So has the ground around the tank been absorbing all that tank effluent over the years? Amazing. Either it's a lightly used system or you've got very absorptive soil.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I learned to tell where it had been leaking the longest by looking for masses of fine, fiberous tree roots. There was quite a mass of them underneath the tank outlet. Further downstream, I found additional concentrations of roots, which were a bear to dig up. Fortunately, it is a VERY lightly used system, just me. The water meter says I use a bit under 1000 ga/month, but I don't see how I use that much. (That's no outside watering). I've started to read the meter myself and do a few tests.Since I just had the tank pumped a few weeks ago, it's still in the process of filling back up, thus no outflow to the field.Absorptive is definitely not how I would describe the soil! It's hard clay with a lot of rock mixed in.
Today I partied some more with the demo hammer. There's about a 7 ft. long section of the trench that bows upwards. Today I understood why it wasn't dug out in the first place. It's extremely dense red clay, mixed with a few masses of tree roots. The only way I could "plane it off" was to dig down vertically about 4" with the demo hammer, move about 6", dig down vertically, etc until I had covered the crest of the bow. Then I went back, with a sharpened spade bit and sliced off sections horizontally to take it out. Sort of like working a bow down with a jointer plane. The stuff is almost like adobe. If the original installers just had shovels and maybe a pick axe 27 years ago, they were hating life when they got to that section. So they just left it. That's where all the pipe cracking/splitting occured. The thin wall went from a circle to an ellipse, until it split right down the middle on top & bottom. After a few hours of work, I was able to "plane down" most of the crown. Then I left to get new pvc.Tomorrow I'll dry fit all the parts, then check the slope. I thought of making some vertical risers/stands/supports out of scrape pvc, strategically placed to support the pipe. I could make a circular cut out on the bandsaw to cradle the pipe. Put them in, then backfill with pebbles and sand. I'm open to suggestions on how to backfill correctly. Incidently, I purchased thick-wall sch 40 pvc for this section. Central Tx just isn't very 'thin-wall' friendly. I'm also testing out different ways to attach a collar to the septic outlet, which has almost no lip at the bottom where it can easily leak. I need some sort of gap-filling adhesive, maybe urethane. I also found I could slide a 4" piece of thin-wall pvc INSIDE the tank collar. That way it would be better supported. It's fits in there really tight. I'd still need to seal it though. With new pipe, there's a bright light at the end of the tunnel. Hope to have it all back together before the weekend.Thanks to all for reading and for chiming in with stories and suggestions. Keep 'em coming . . . .
We moved into this house in Feb. About 10 days later DW said, the toilet isn't flushing right. I made some smarta*** comment, and took a shower. The shower pan filled up with "dirt". Called builder who came out with a plumber. He stuck one of those little TV cameras in the outside cleanout, and called a Backhoe. The connection to the city sewer line had never been connected. By 4:00 pm it was hooked up and backfilled.
We have good builder, but how does that happen?
Stef
A good Builder who trusted a Good plumber who was trusted by a Good inspector who had too much too inspect in too short a time. I have seen the same, or similar things happen. Yet we gripe about people looking over our shoulders to see if our work is done correctly. If I take those checks on my work less personally and viewed them as a needed check on my own forgetfulness I do a lot better.
They can't get your Goat if you don't tell them where it is hidden.
Thanks for posting the pics. Would you mind if I "borrow" them for a training class?
Not at all. If a picture is worth a thousand words, perhaps a color picture is worth a lesson. Here's what'll happen if you don't do it right the first time. It reminds me of that saying You don't have time to do it right the first time, but you do have time to do it all over?What's up with that?
Where does the good part start?
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I've attached some photos of the new pipe and glass'd tank outlet I installed. I found a slip repair coupling which solved the problem of installing new pipe between two unmovable ends. The day I was gluing up, the outdoor temp was sitting at 99. The pipe glue would evaporate/set up so fast I didn't have time to push in the pipe! So I put the can of glue into an ice water bath for several minutes to cool it off and it worked like a charm! The new outlet piece glass'd onto the septic tank is very rigid and watertight. I'm pleased with the way that came out.Next week I'll get a load of sand to backfill the trench, no way I'm putting that lousy clay/rock infested mess back in. Now I've got to find a place to get rid of it.I'm glad this project is over . . . .