# Anyone know anything about Septic Tanks?



## bbroderi (Jun 9, 2021)

Hey guys,

Does anyone know why my septic tank would have a huge hump over it? I will attach a picture of it later today, but basically the ground was purposely left higher by several inches ~15 years ago when it was put in, and its an eyesore to look at. I have not probed to see how deep it is below the hump, and I know nothing about these systems. I assume whomever installed it either needed the surface to tank depth to meet some code requirement, or they didn't care enough to level it out. I'd really like to level it out if I can, but no clue how it will effect the system. Thanks!

Street view from 2012


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## Redtwin (Feb 9, 2019)

Are you sure the hump is the tank? It could be the drain field in which case you wouldn't want to mess with it.


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## bbroderi (Jun 9, 2021)

Redtwin said:


> Are you sure the hump is the tank? It could be the drain field in which case you wouldn't want to mess with it.


Until I get home, I can't get a good shot, but I added a street view of the house from 2012. You'll see the area in question is right off the house, and there's a cover in the mound between the house and the hump which I presume is for draining the tank. I would think the leach field would be in the front yard. Back yard is a little too muddy for a tank, so I'm presuming this has to be it.


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## Amoo316 (Jul 8, 2021)

Yeah they do that for the drain field. It's basically a toplayer on top of your existing surface with sand &/ rock and pipes.

Here this explains it better:

https://humboldtgov.org/2208/Understanding-and-Maintaining-Mound-Syst

Only thing I would add there is not all systems even have a pump and rely completely on gravity. In those cases, like mine and yours most likely, everything starts off high and gravity does all the work on moving the waste and water through the chambers.


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## bbroderi (Jun 9, 2021)

Amoo316 said:


> Yeah they do that for the drain field. It's basically a toplayer on top of your existing surface with sand &/ rock and pipes.
> 
> Here this explains it better:
> 
> ...


If everything needed to drain down hill, it would make more sense that the tank is under the hump since the rest of the yard is below it. Right?


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## PNW_George (May 28, 2018)

Can you get a copy of your septic system design? Lots of variables; Generally it will include at least a double compartment tank with two access covers unless it is a much older single tank system. The end of the system is the drain field which is usually indistinguishable under a lawn and far enough away from the foundation because it needs to perc. The tanks are generally near the house in a place where they use the dropping slope of your lot.

Between the septic tank/s and the drain field there can be additional components. Simple systems allow for a gravity flow design. Others require a pump tank in addition to the septic tanks. Others may also require a sand filter after the pump tank and before the drain field. My sand filter design has no hump but does have a couple PVC vents that stick out above the lawn. My neighbor's sand filter is a later design, likely with more stringent code requirements, and is raised above the grade of the lawn.


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## Amoo316 (Jul 8, 2021)

No the tank is at the top, then the tank drains in the box which is slightly lower, then that drains into the field.

The picture from the site shows the tank and box below only because they have a pump.

Essentially, you'd be paying to put in a new septic system + removal of the old drain field and only get to reuse your box and tank if you wanted to level it.


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## Redtwin (Feb 9, 2019)

A lot of the houses in my area use the elevated drain fields because of the very high water table here. I don't really see any way around it other than connecting to city sewer (if that's even an option for the OP).


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## Monocot Master (Feb 28, 2021)

This was touched on in some of the other posts. Here is my take on it. You most likely have a conventional, gravity fed septic system. In this type of setup, the tank depth is directly related to the depth of the drainfield. So the key variable in siting the drainfield is where the seasonal high water table is located within the soil profile. Soil absorption wastewater disposal requires aerobic soils to function properly, so there must be a zone of suitable soil where your drainfield sits. Most likely, your drainfield is relatively shallow, which results in an even shallower septic tank.


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## bbroderi (Jun 9, 2021)

I bought a manual edger and was edging around a pine straw mound near the hump. I ended up hitting concrete, maybe 4-5 feet wide...this has to be the tank. The good news is there's maybe 2" of topsoil where I was edging, which is at the bottom of the hump, so there' slike 4-5 inches at the peak. My hopes are that one day I can remove the sod and lower the hump by a few inches so it isn't so much of an eyesore. I wish I knew why they just didn't dig a little deeper when installing the damn thing.


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## Burnie (Jun 13, 2020)

https://www.mecindustries.com/morse-engineering-and-construction-industries/pros-and-cons-of-mound-septic-systems


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