I have a drain of porous, ribbed, very old clay pipes, leading from my septic tank.

A short area (18") has collapsed.

Rather than try and replace the pipes in any way I'm thinking of installing an inspection chamber at the site.

Would this be the best approach?

And what am I looking for?

Drainage Sales have:

450MM INSPECTION CHAMBER COMPLETE SET WITH POLYPROP COVER - FOR 110MM DRAINAGE
CODE: 450MH1

which looks as if it might do the trick. But I have absolutely no experience so any comments would be very welcome.

Keith