Septic repair question (tank, tanks, drain, installed)

[38wildwood]

Hi
I have a 4" Sch 40 pipe connecting my septic tank and filter box (system installed in 1981). Both ends were sealed (not) with plumbers tar 5 years ago when the prior owner had the tank re-set after it shifted and broke the pipe from the house due to a failing wall which was also rebuilt at the time. It's apparent the leak has been active from probably not long after the work was completed as a very large tree immediately below the wall died within 3 years of the work.

Concrete is in good shape however holes are a little rough and are beveled, wider on the outside of the tanks. I'm looking at best possible and most permanent repair solutions for the least amount of work, and after reviewing several I have been told hydraulic cement is the answer. My problem with that solution is, I know a little about the difference in the coefficient of expansion of PVC vs. cement or concrete and am concerned about how long it will be before I'll be digging again.

I've reviewed many other options but they remain in question.
a few are:
A-Lock (requires massive hole and casting a sleeve into the tank)
Link seal (unlikely to hold in a beveled hole)

Anyone have any ideas or had experience connecting pvc to concrete?

I could easily go with a smaller pipe, say 3", since the flow is nowhere near even 1/2" of that " pipes capacity.

[Cosmic]

Unclear to me exactly what is busted.

Is the tank cracked or is it just the connection to the tank for the piping. Or is nothing busted, just need a good seal at the tank to the drain line.

They make a variety of rubber boot type connectors for PVC to connect PVC drain lines to other materials. One of them is a PVC to drain clay tile type rubber boot. It is just a pressure fit type system where the pipe is cut a tad long and pushes the boot into the tank socket, backfill secures it. Sounds like what you are describing.

Number of other rubber connector designs. Most home centers have them. The boots slide over the drain line, their shape corresponds to the shape of the receiving socket, you get a press fit which compresses the rubber, backfilling keeps it in place. They don't leak if done right. Always have the drain line cut a tad long, let it hump up a bit, pushing the line down, start backfilling away from the tank, work toward the tank. This causes the line to push in, giving a good seal once the dirt is over the entire line. It is a judgement type thing to allow just enough working extra in the pipe to get it back to the proper slope with a good pressure being put on the boot.

[38wildwood]

Pipe to tank connection is the issue. This pipe runs between 2 concrete tanks.

I have explored all the "readily available" home store, local plumbing supplier type stuff, none will work reliably in a rough and beveled hole. Backfill pushing the pipe in either direction would pull it from the other. That's why I looked into the specialty sewer fittings I listed.

Thanks

[Dubebecky]

What do i use to seal a rubber coupler into a cast iron sewer pipe. As the coupler slides into the pipe and is not sealed correctly and is leaking.

[K'ledgeBldr]

Originally Posted by Dubebecky

What do i use to seal a rubber coupler into a cast iron sewer pipe. As the coupler slides into the pipe and is not sealed correctly and is leaking.

Are you referring to a donut coupling? Is it being used properly? And is the right size pipe being used?
Is this cast iron-to-cast iron or PVC-to-cast iron?

Establishing if the correct part(s) are being used as designed- otherwise the "fix" is temporary at best. Perhaps a picture- would help tremendously. If you use a pic host website- you don't have enough posts to post a pic here; yet.