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 Septic tank backed up
Author: Captain Ron (KY)

Septic tank backed up, could not flush toilet. Had tank pumped out. Septic system was installed over 35 years ago.

This was the second time it has been pumped out. Ran a rotor rooter down main line, no sign of blockage. Dug up main line from Concrete Septic Tank to Concrete D Box approx. 40-50 ft. long. D Box was totally crushed.

I have had several heavey loads delivered over D Box over the years. I did not know where it was located. I do now.

We found that the elevation where the pipe exited the Septic Tank was approx. 12-15 inches lower in elevation than where the other end of this pipe entered the Concrete D Box. The pipe had been installed with a gradual incline of 12-15 inches in 50 ft. where it entered the elevated concrete D Box.

We ran the new pipe with a slight decline in elevation from the Septic Tank to the New Plastic D Box that we installed. The new plastic D box sits lower than the original Concrete D Box by about 12-15 inches. Therefor the ends of the lateral lines where they exit the D Box are now about 12-15 inches higher than the outlets from the D box where the lateral lines exited it before.

My question is this, will the water flow have any problem going to the D box and then making the rise of 12-15 inches to the lateral lines? If no, does anyone have any suggestions?

Immediately after the 12-15" rise in elevation from the exit at the D Box to connection with the lateral lines, the field tile lines run downhill from there on.

Edited 2 times.

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 Re: Septic tank backed up
Author: bernabeu (SC)


.....The new plastic D box sits lower than the original Concrete D Box by about 12-15 inches. .....

? WHY ?

Put it back where it should be.


Edited 1 times.

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 Re: Septic tank backed up
Author: packy (MA)

in effect, you have created a drum trap out of the D box.
the water will lay in the inlet pipe as you can see from this picture.
it will work but it will require much more frequent cleaning.
just how much more depends on how well the septic tank is functioning.

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 Re: Septic tank backed up
Author: Captain Ron (KY)

I don't know why the original D Box that was crushed was at an elevation 12-15" higher than the exit from the Septic tank. The only possibility I can think of is that maybe when they dug the lateral lines they might have hit sandstone which could have caused them to raise the lateral lines higher than the Septic tank. However, since the lateral lines from the D Box connection all flow downhill after the high hump, I was wondering if you think it might work?

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