septic tank lid stuck

[Ether Jones]

Just dug up the septic tank to get it pumped and I cannot lift the concrete access cover. It is "frozen" in place (more like "chemically bonded" I would say).

The tank is concrete and the access cover is concrete. The access cover is rectangular in shape, about 12"x18". It has an iron handle cast into the center. The sides of the cover are slightly angled so that the cover fits snugly down into the access hole (like a stopper in a utility sink).

I tried prying the cover up with a bar thru the iron handle. It doesn't want to budge. Any more force and I'm sure I would break the iron handle. I tried prying the cover up around the edges with a crow bar but it just chips the concrete.

What are the recommended ways of dealing with this situation? Should I use acid or some other chemical to try to break the "bond" that has formed between the cover and the hole?

The tank is 11 years old, and I don't think the cover has been removed since the tank was buried (cover is about 8" below ground surface level).

[mm]

Let the pumping company handle it?

[nicksanspam]

You might use a tripod or a 55 gallon drum on each side with a beam and a comealong to put (say) 500 pounds of uplift on the cover handle for a few hours while sprinkling hot water around the edge and bonking it with a 4x4. You could measure the cable tension by pulling it sideways with your hand or a fish scale. A 4' cable with 500 pounds of tension would move sideways about 1/2" with a 20 pound force in the middle.

Nick

[Nick Hull]

I had the same problen, except the tank had been 4' underground for 25 years. I chained my carryall to the handle and lifted until the front wheels of my tractor became airborne. After a while the lid came out.

Suggest you get a comealong mounted on a tripod and pull with a NYLON rope so it stretches (NO more than 10%!!) and let it sit in tension for a while. Maybe even dump boiling water on it to soften the tar paper seal, then put an ice block on the lid to shrink it.

[Bob]

I'd try washing out the gap between tank and lid with a strong hose blast or pressure washer.

Bob

[Ether Jones]

and

[e-mail] wrote:

Thanks. That did the trick.

I built a small earth dam around the cover and dumped 2 gallons of boiling water in there. Waited 3 minutes and tried the pry bar again; the cover lifted right off.

Amazing.

[Pop]

... A 4' cable with 500 pounds of tension

Woof! Do you know that by empirical experience or is there some magic lay-formula to use? Wouldn't it depend on the cable composition?

Pop

[nicksanspam]

With 400 pounds of cable tension and a sideways deflection distance d and deflection angle a, 2x400sin(a) = 20 makes sin(a) = 0.025 = d/24, approximately, for a 24" distance (half the cable length) so d = 0.025x24 = 0.6".

Not much.

Nick