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Community and Q&A

Excavating for a Septic System on a Sloped Site

steveeee | Posted in General Questions on

i’m working on trying to get a septic permit for my land. i met with the health department inspector yesterday and we found an area with acceptable soil but its not that big an area as much of my land doesn’t have the soil depth

anyhow the big problem is all the land is on a 30% slope and septic lines have to be perfectly level so i have to follow the contours of the land. the inspector said i need 240 ft of line for a 3 bathroom permit.

i’m probably going to do the digging myself as i can’t find any excavation company here to do it but i’ll keep looking

the problem i have is the health dept. inspector said when i dig the trench i cannot disturb the soil above or below the trench. how do ii do that with an excavator? i can’t safely drive and dig with the tacks sideways to a 30% slope, i’ll risk tipping over without the blade to stabilize.

i guess i can face the track up and down, use the blade then swing the boom to the side, not ideal but i guess that’s the only way.

any advice?


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  1. Expert Member
    Michael Maines | | #1

    You can use a small excavator in line with the distribution pipes, or you can use a large excavator with a wide bucket from above or below. Do you have an approved design from a septic system designer? They may be able to find a way to reduce the size a bit, and will show the important details.

  2. Expert Member


    Here in the land of sloped terrain and rocky outcroppings, we have various disposal field designs to cope with differing conditions, it would be highly unusual to end up using a conventional field with long runs on a site like yours. Money spent on a septic designer would be money well spent.

  3. AlexPoi | | #3

    Some advanced secondary treatment septic systems don't require as much soil depth as a traditional drain field. They are more expensive but they may save you some money digging a long trench. I agree with Michael, I would hire a septic system designer. Could save you a lot of headaches.

  4. steveeee | | #4

    i'm just going by what the health department guy said, he said there is an option for a drip system but its expensive and needs a lot of annual maintenance

    if anyone has a specific example of a system i should look into please let me know. i have about 1/2 acre of land but the area with the deep soil is quite small, maybe 50' x 50'

    the area with shallow soil is about 100' x 50'

    i wish i could get a septic designer to come look, a couple of people said they can look in July or later

  5. walta100 | | #5

    Consider a Chamber field System you get a lot more surface area per foot of excavation.


  6. steveeee | | #7

    i think the chamber system is the standard everywhere isn't it? the health department guy's calculation of 240' was based on that kind of system.

    i'll ask them about the ENVIRO-SEPTIC thing, if this allows me to use shorter leach lines. i see they claim 40% shorter but in the end, its up to the county health dept


  7. walta100 | | #8

    From what I have seen chamber systems are the new kid on the block and represent a small percentage on installed systems but are becoming more and more popular.

    1. steveeee | | #9

      maybe if you are talking about already installed but i think for new installation, the assumption is that unless there is a reason, the chamber system is what most new permits specify

  8. walta100 | | #10

    Generally your installer would design a system and the county inspector would approve his plan and inspect its insulation before it was covered up.

    It is not really the inspector’s job to design your system yours seems to be more helpful than most but understand there are many things that have to get done correctly for your system to work and the inspector may get tired of being an instructor at some point.


  9. Expert Member
    Michael Maines | | #11

    I don't know if other states have this, but my state has a good design booklet available online--I refer to it often for preliminary site evaluation, though I'm not licensed to design the system.

  10. dfvellone | | #12

    I well understand it's hard to hear, but if you can somehow wait for a designer/engineer or expand your search to connect with one who might be available sooner it would be a great help. Septic design isn't generally an aspect of an egineering firm that you should have to wait for months on. It's usually a quick and easy paycheck for a competent designer. Your local inspector, though likely knowledgeable about septic systems, isn't a septic designer or engineer, and although he has final say should defer to an engineer's design. A basic septic system is a fairly simple, cut and dry project, but depending on site and soil conditions there's plenty obstacles and hurdles that would easily justify the expense of and even the waiting for an engineer or designer.

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