Septic lid/cover disintegrating

[pepe]

My septic tank lid is disintegrating. I'm not talking about the access cover, I'm speaking of the large lid that covers the entire tank. My first indication that something was wrong was when the access hole got too big for the access cover. And that hole has been getting bigger ever since. I keep it covered up with a sprinkler box, but I fear that the entire thing will cave in, probably when the neighbor's kid is right on top of it.

Yesterday, I put a camera down there and took the attached photos. I know the tank will need to be excavated and the cover replaced, but I'd like to know what is causing this apparent fast disintegration. Is it my water softener, do I poop too much? What could it be? By the way, the tank is about 23 years old.

Thanks.

Pepe

[Bumblerazz]

I'm not sure what would be causing this erosion of the tank. Someone with more knowledge may be able to help you there, but it seems a little odd to me.

How quickly has the erosion occurred? Is this over the past month or over the last few years? 23 yrs is usually considered the life of a septic tank, give or take.

On first glance it looks as though the cement is de-calcifying. Normal gases found in a septic system would not do this (or do it very, very slowly). Do you use strong cleansers or flush medications or paint down your toilet? Have you been using a lot of bleach lately? Chlorine gas or some other acidic vapour might do this. Have you had bad acid rain lately? Any unusual surface liquids leaching into your septic?

[AllanJ]

Is the top of the tank less than three feet from the ground surface level? You may be having freeze-thaw damage (spalling) on the concrete. This occurs little by little.