How Far Down is My D-Box Lid?

It’s a lazy weekend afternoon and you have nothing to do but lounge around in your yard and just relax. But just as you are about to doze off, your wife comes up to you and reminds you that you should do the errand that is over a month old already. Yes, it’s your time to locate and inspect your distribution box or “d-box”.

Your scheduled self-maintenance for your septic system was a month ago and you know very well that if you don’t do it soon, you will just be like your neighbor whose entire yard became a sewer kiddie pool. But before you go to the tool shed and look for the necessary tools, there’s just this one problem that you need to address. How will you find your d-box lid and exactly how far down is it?

Not all homeowners are fortunate enough to know the exact location or depth of their d-box lid. This is an important component of your septic system that you have to locate so that you may be able to perform maintenance on your septic pipes. Once you have located that d-box lid, everything would be fine from that moment on.

First thing you have to do is know where to excavate. Your wife will not be very happy if you dig holes all around the yard just to try and find the d-box lid. You really have to gain the exact information about your septic system installation. You can get a diagram of your septic system from where the installer obtained the septic installation permit from. But do not depend on this because the diagram or perspective that you can get from the permit office would just very well be the original plan and may differ from what you actually have buried in your yard. You may not have been aware of some minor changes that the installers did in the actual installation of your septic system and the depth of your components may not exactly match what is on record.

If you have already obtained the diagram but think that it may not be that much help, just look at your yard for the dark green grass that grows on top of your drain field. This grass may be lusher than the other grass on your yard because of the continuous flow of treated effluent. If you can determine where these lush green strips originate, that will be the location of your d-box and your best bet would be to begin digging in that area.

Another method used to locate the d-box is through probing. Taking a thin metal dowel, gently push around the tank area until you locate the outflow line leaving the tank. This outflow line is 3 to 4 inches in diameter and will exit the septic tank at around 8 to 12 inches below the top of the tank, pointing in the direction of the drain field. Using the probe, tap down on the exit line and walk a few feet. Keep tapping down every few feet and “stay” on the line. This method will lead you directly to the d-box and can also be useful for mapping out your entire field, and its depth, once you become accustomed to using your “finder”.

The question left now is how deep will you dig? Experts say that you would have to dig two to four feet deep once you have found the location of the d-box lid. Some people are not even sure when they start digging at the suspected location. They try to use a metal detector to detect the metal reinforcement of the d-box. A metal rod is a bolder means to get to your d-box but you have to drive it through the soil until you hit something hard. And that could be the concrete container or just a stray rock. Usually, the d-box is about as far down as the line that leaves your septic tank. Of course, the further away the d-box is from the tank, the deeper it will be. With that being said, since you only need a small pitch for water to flow, the d-box may only be a few inches lower than your tanks outflow line if it is within 30 feet of the tank.

What’s important is that you know how deep you’re going to have a part of your yard dug. It is best that you consult a septic professional if you really want to be sure about the location of your d-box lid and to avoid any confrontation with the wife on the several holes you might put into the yard. Once you get that primary and vital information, you need to make that lid accessible for your future maintenance efforts. It can be quite challenging for anyone with a septic system to locate their distribution box but with a little effort, they can be found, inspected and serviced.

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