View Full Version : problem tying into drain at septic tank
06-13-2012, 09:31 PM
Hello - I want to tie the soil pipe from our new house into the existing septic tank on the property. The problem is that the existing PVC pipe at the septic tank is badly out-of-round, it's basically flat on top. I'm sure I can't cut into it and glue a fitting on as I had planned. I want to find a way to use that pipe as I don't want to chisel it out of the concrete septic tank and mortar a new one in, I haven't done that before and it could leak (most likely would leak I mean). Any suggestions on how I might use the existing, deformed pipe? I've looked at the shielded Fernco couplings, don't know if that would be strong enough though.
Thanks for any help.
Well, in the first place the pipe that was used is a piece of c***. It is SUPPOSED to flatten out because it is too thin to do anything else. It is also undersized so you need a "bushing" to make it large enough to fit standard pipe and fittings. Cut it about 3" from the tank. It will be round enough for the bushing to fit and that will finish rounding it out.
06-14-2012, 08:31 AM
... Cut it about 3" from the tank. It will be round enough for the bushing to fit and that will finish rounding it out.
Yes, but first see how far you must go the other way to get to a round spot where you can re-connect.
06-14-2012, 06:44 PM
The inlet on a septic tank should be 2 inches higher than the outlet, so it is not likely to leak out the inlet end. It should be easy to grout the annular space around the inlet pipe. You need to dig out enough so you can work. I would remove this mashed section of pipe. You should be able cut it back several feet from the tank and remove another 12-18 inch section so you have room to back out the section in the inlet. If you leave a 2-3 foot section hanging out of the tank you will have enough leverage to wiggle it out of there. You may have to enlarge the inlet to get the new pipe back inside. Replace the pipe and put it back in the inlet. Grout around the pipe in the inlet. You can use the soil to make a form and pour a plug around the inlet and pipe. If it gets a little messy it does not matter because you going to cover it up. Fill the ditch up with dirt. …. Also another option might be to use another inlet. Most precast tanks have three inlets, one on the inlet end and one on each side on the inlet end.
Depending on the tank, that piece could be attached to the "baffle tee" inside the tank. It appears that the "other end" of the pipe will be the NEW pipe from the building. I have NEVER seen a tank with "three inlets". IF you remove that pipe the hole will be to small to slide a new pipe into it, and trying to make it larger can be very taxing.
06-14-2012, 08:04 PM
I didn't mention that the pipe does come into the inlet tee inside the tank, the tee is concrete. I think I'd have to have the tank pumped to replace the tee if I happened to break it chiseling out the opening. Did I mention that the smell is something else when the lid's off this thing? Well, it is, but that won't deter me. Also, somebody planted a big tree right on top of the drain pipe about 1' to the right of where my photo ends, no wiggle room to speak of there. The tank has been in place for around 40 years.
HJ, you mention a bushing, is there a specific bushing for going from that thin PVC to 4" ABS? I think I'd like to try that first, if it doesn't work I'll have to consider replacing the pipe through the tank wall.
I appreciate all of your replies. Thank you.
06-14-2012, 09:08 PM
HJ his tank may not have three inlets, but it is the law here in NC for precast tanks and has been for at least 30 years. Also we do not have Tees on the inlet here.
15A NCAC 18A .1954 MINIMUM STANDARDS FOR PRECAST REINFORCED CONCRETE TANKS
(a) The following are minimum standards of design and construction of precast reinforced concrete septic tanks:
(4) There shall be three inlet openings in the tank, one on the tank end and one on each sidewall of the inlet
end of the tank. The blockouts for these openings shall leave a concrete thickness of not less than one inch
in the tank wall. The blockouts shall be made for a minimum of four-inch pipe or a maximum of six-inch
pipe. The outlet pipe penetration of the tank shall be through a resilient, watertight, sealed, non-corrosive
and flexible connective sleeve. The outlet pipe penetration shall be precast to be compatible with the
connective sleeve. No pipe penetration points or openings shall be permitted below the tank liquid level.
The bushing is for SDR to sch. 40 pipe. There is only one for each pipe size.
06-15-2012, 12:20 PM
Every tank I saw in the last 30 years had 3 inlets. No matter, dig back some more and if the pipe is really cr*&, it will deform easily for a standard fitting. Or use a clamp-glue on cut in wye and not have to screw with any issues at all.....
http://www.kenoshawater.org/images/KWU_Sanitary_Sewer_Specifications_8-07.pdf scroll down to "cut in wyes"
http://www.grainger.com/Grainger/FERNCO-Flexible-Tap-Saddle-WYE-3HDF4?Pid=search Not the right size but this gives you the idea... Pour cement around it if someone is going to drive on that area
quote; if the pipe is really cr*&, it will deform easily for a standard fitting.
"If the pipe is really SDR", (which it almost assuredly is from the photo), it is "undersized" compared to standard fittings will NOT "deform easily" to fit them. The section about "cut in wyes" applies to mainline sewers 6" and larger, NOT a house line, and the Grainger saddle is NOT approved for that use either, adn since it is sized for sch. 40, it will NOT match the o.d. of his pipe. Our precast septic tanks come with ONE inlet and the baffle tee and pipe stub are preinstalled in it.
06-16-2012, 12:21 PM
I would look for a better tank company. Many tanks cannot be dug one way and the straight shot in is worth much.
The plastic cast
4 " saddles are common and can be had in rubber. Seems to me the SDR mixes with other pipe and fittings in my collection
and the OD is the same. Never saw a fitting marked "SDR".
You won't. You just have to recognize it by the smaller i.d. of the bell, plus the fact that the bell is basically just an enlargement of the pipe itself, and many are gasketed push in fittings also. IF you THINK the OD is the same, then you have NEVER worked with it. For flow compatiblilty reasons the I.D. is 4", the same as sch.40, but since the wall thickness is considerably less the O.D. is SMALLER. IT IS NOT like cts plastic where the o.d. is constant and the i.d. varies according to the wall thickness.
06-17-2012, 04:33 PM
Probably a terminology or geographic issue. They sell pipe here you can't stand on, but it fits the regular heavy wall pipe fittings. Good for gutter extensions and far off yard drains, but not much more - except marking mining claims.
That is an irrigation pipe, probably Class 100. If it were used for sewage, there would be an "offset" in the flow at every fitting.
06-20-2012, 09:30 PM
Hello - Update on my project...
There is only onel knockout on the end of the tank. A septic installer came by yesterday, he says it's not too hard to get the old pipe out and grout a new one in, he says he'll help if I want.
1- what sort of pipe should I use for the sewer line from the house to the septic tank? I had planned on using 4" ABS, is there something else that would work as well but cost less? It's an 80' run.
2- Also, should I lay the pipe at 1/4" drop, or is steeper OK? Code here is UPC.
Thanks to each one of you for your help on this!
If you "get the old pipe out", you will have to install a new baffle tee inside the tank and make the opening in the tank bigger to accomdate the ABS pipe. DO NOT use SDR again even though it WILL BE cheaper. With 4" pipe 1/8" is the "minimum", but you can go as steep as you want, after all "vertical pipes" have an INFINITE slope and they are legal.