How deep can septic be buried?

[Connor Heim]

Howdy folks. First time poster here.

I recently built a new home, and our concrete septic tanks are located in an area of our yard that is about five feet lower than the rest (they used the dirt from that area for our building pad). I want to bring in more dirt to level that area off with the rest of the yard. My installer is concerned that adding excess dirt will cause the tanks/cover to collapse.

I mentioned maybe installing some sort of a collar extension over the access point, but he didn't seem convinced....

Is there a maximum depth that is safe for burying the tanks without damage? I'm not sure if it matters, but this is a conventional system, not an aerobic system. I'm hearbroken because right now, I have a huge bowl next to my house, and my plan has always been to fill this in and have a nice lawn there. Right now it's just a silly looking bowl.

Please let me know your thoughts. Thank you!!!!

 

[Jadnashua]

Other than access to clean the tank or service things should they need it, I don't think additional depth is a problem. Is the tank concrete or some other material? If known, I'd consider calling the tank manufacturer for verification. You may be able to buy a section of concrete culvert pipe for access so you don't have to dig when it needs to be serviced. If the soil perk is good now, adding more on top shouldn't be an issue with performance. Now, depending on construction, driving a full dump-truck over the field to get the soil closer could be an issue.

How much fill are you talking about at maximum needed additional depth?

 

[Sponsor]

 

[Connor Heim]

Jim, Thanks for your response. Yes, they are concrete. I am guessing they are currently covered with appx 2' of dirt. I'd like to add another 4 feet or so, which would make them buried about 6 feet down.

No trucks would be driving over the field... it is further out in the yard away from the access of the trucks.

Anyone else able to weigh in?

 

[hj]

I have seen them buried 10' down, but the only problem with that is access when it has to be pumped or serviced.

 

[Widgit Maker]

Additional soil on top of the tank should not be a problem unless it interferes with servicing. Septic tanks have to pumped periodically to remove undissolved solids. Do not fill over the septic distribution lines. Not only are the fluids absorbed into the soil but also evaporated by the sun.

Suggest you call septic tank servicing company to see if what you want to do will interfere with pumping.

 

[Builderbuddy]

In our area when a tank is buried more than 3' in the ground, an excavator is needed to access the tank- this drives up costs for the homeowner and makes inspection, pump, and repair access very difficult. I have also witnessed firsthand that over-deep septic tanks have presented a lot of challenges for buyers and sellers during a real estate transaction. I would have riser lids installed on tanks over 3' deep and try to avoid going over 4' or 5' if at all possible.