How long do sewage basins (poly) are supposed to last?

[Justnutsandbolts]

I am removing my old one out because it is damaged around the lip and when lifting it up, I noticed it is also broken at the bottom.

Model is JACKEL INC SF24x36 ..... POS brand and POS company

New one is a Zoeller Brand Z311102 .. another POS (it has a flimsy base and I don't like it)

House was built in 1985. There was orange fill around it.
How long are these things supposed to last below grade?

I am thinking about just placing it above grade for easy maintenance.
or building a pit out of concrete around it with some space.

PICS:http://imgur.com/a/MiqeL

 

[frodo]

it it was not set in a 12'' bed of sand, it was installed incorrectly

foundations move, so does the earth. it needs a bed around it to cushion it against the rocks or hard chunks of earth

that will heave up and down,

 

[DFBonnett]

Mine has been in place since 1989. Don't know the brand and the plumbing supply where I bought it is out of business. Installed pretty much as per method outlined by Frodo. Tank is fine. Two piece steel lid is rusting from the inside out. Can't seem to locate an exact replacement so I don't have to move vent and discharge lines, but I am still looking.
To answer the question as to how long they last, I would say indefinitely as long as the installation was done correctly.