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Question regarding wall and septic feild..


LawnSite Gold Member
northern jersey
I am suppose to start a big project in the morning. I just want to run this past you guys guys.

I am building a retaining was in a backyard. The wall will be 3 feet high. Righ now the back was is just a step hill. My wall will run parraell to the house. Between the house and where my wall will be constructed is the septic feild. I will be bring in about 20 yards of fill to level off the yard after i build the wall. I will be putting dirt on top of the septic feild. I just want to make sure added 3 feet of dirt on part of a feild will damage it or anything. This back yard is steep as heck, i do not even know if i can drive a skid steer accross it. A septic feild has to be installed level to begin with. If it was installed level there must be like 4 feet of fill on the onside of it.

What do you guys think? I am not an expert on septics.



LawnSite Platinum Member
theres about a dozen differnt kinds of septic fields. some have lateral lines that need to leach and adding dirt on the top can cause problems. With thee fall it sounds like an aireation system with just one line going down the hill. If it is then you won't hurt it. But local codes call for so many ft of leaching tile covered by so much soil on most systems. So check the local health board they should know what system was installed and the code that you can follow


LawnSite Senior Member
New England
You probably should have looked into this earlier than the night before the job started. I am no expert on this but was once told that something like 70 or 80% of what goes into your leach field actually evaporates through the surface of the field and does not go into the ground. Thus covering it with that much fill would hinder it's performance. I know my old boss covered his like 6 feet and suprisingly had no problems with it after something like 15-20 years. Again I am no expert but would certainly take the time before you start to investigate this further with the appropriate town officials. Please keep us updated I will be interested to hear your outcome on this. Also driving equipment and trucks over your field is not a good thing. Septic tanks themselves having different ratings. Some you can drive over and some you cannot.


LawnSite Gold Member
northern jersey
I am looking into this today. The project has two walls. So i'll start working on the first wall. I will not be driving or riding equipment over the field and i am no where near the tank.



LawnSite Bronze Member
North Jersey
Alright well mrusk I wouldnt worry to much about it. We did a huge job in august with that included a lot of hardscape, softscape, and a huge topsoil and seed job. The septic tank and leech field were basically in the way of our only access into the yard and we had been driving skidsteers, trachoes, a john deere 310, and a kubota across the area and never damage anything. We also had to fill in on top of the tank and leech field to level out the yard. On another job we built a retaining wall right across the front of a septic and filled in the small yard on top, never had a problem, they are built pretty sturdy, but its one of those things that you avoid as much as possible just not to ruin your luck.


DVS Hardscaper

LawnSite Fanatic
County Jail
The septic tank and the septic field are two different things!

If you are working over the drain field, i suggest you speak with the local county health dept first. More than likely there will be NO problems. But I have found that our local health dept wants to have final say about what is done.

CYA. ALWAYS CYA. Better to be safe than liable!


LawnSite Member
I'm a little late to the party, but I wanted to add my 2 cents.

I've been in many of these discussions before and I wouldn't add more dirt to the drainfield without discussing this with the local health authority. Plenty of folks say they drive on their fields or buried them deeper to level their yard and they almost always say it didn't hurt anything. Just because the toilet flushes doesn't mean its working:dizzy: How do you think ground water gets contaminated with fecal coliform??

We just peeled 2-3 feet of dirt off a drainfield because the original installer buried the drainfield too deep :angry:

If you're still not sure, check out the website and see what you think.