Building a Home: Failed Perc Test

Does anyone know how to increase soil percability?   We want to build our home and keep hitting rock.  Were in East Tennessee on the Cumberland plateau.  Its a sloped section.   Most areas have barely a foot of soil before hitting rock.  A few have required 36 inches but it´s clay and water runs right off it.  Is there a way to get percable soil?

If you can't pass a standard perc test, then you should check with the approved testers to see if they allow alternative systems.

I was having similar issue with first backhoe hitting rock. I was told that the alternative septic system is an option, but the price was $12k-$15k versus the $4k -$6k for regular septic.  

There is the pump +  sand mound way of solving this.


There is also the aerobic (air pump) + chlorine disinfictant + water pump way of solving this.

Watch the entire video. You could easily fit this system in your basement.

Thank you all !

Around here, if a septic system perc test does not pass, an evaporation mound is required by Code. They work. If installed by a company, they are an additional expense (not cheap). This is usually an issue with heavy clay soils. But if you can provide your own sand mound of a certain volume, you may be able to squeak by and save a bundle.

What area are you planning to build in, somebody may have a solution nearby?
Have you thought of alternative systems, separation of fluid, incineration / composting of solids. A worm system?

Research a biogas reactor. Design one, get an engineer to stamp and off you go.
And you get a little bit of gas for your grill.

Rodney Cameron wrote:Research a biogas reactor. Design one, get an engineer to stamp and off you go.
And you get a little bit of gas for your grill.

It's not a bad idea; but implementing it is complex. Getting that engineer's stamp isn't easy breezy peasey. The gear-head in question is putting his/her/their professional head on the chopping block. I'm also not sure about the cash cost of that sort of setup. Thoughts?

Pumped systems are the next answer.  They are basically a large raised pile of sand and gravel designed to operate by evaporating the water where there is rock or clay preventing a normal bed.   On a steeper hill side they can actually work without a pump assuming the line out of the septic tank encounters enough fall to get it solidly above ground level and into the evaporation bed.  We did have part of our pumped field freeze up at the church during Covid.  We were told it was because of lack of use mixed with intermittent use letting it get cold.


As for methane digesters household alone I would strongly question practicality.  The have been doing them all over the orient for farm situations.  They state that 3 to 4 animal units worth of manure is needed to provide just cooking gas for a household of 4.   A 1000 pound cow/bull counts as 1 animal unit.  I have looked for years for how many animal units is a human worth without any site providing a clear answer.  If average human weight depending on where in the world runs 130 pound in asia to 180 in the US lets call it 150 pounds.  So if this is a valid assumption, basically we would need 6 people to produce 1/4 of the manure needed.  If the locations had enough other livestock to produce the rest fine.  Also needs an equivalent dry weight in other organic waste like weeds, cooking scraps, garden waste etc.  One of the problems is that the digestor won't deal with fluids well.  Average US household uses 1400 gallons a week which needs to be disposed of thus the septic fields.  Now you can greatly reduce that by keeping grey water separate.

The wild and crazy dream here would be a solar heated wet sump outhouse(back up for main sewage) built over the septic tank with 2 vacuum tanks well insulated in back.  Pull a tank to vacuum and suck the solids up from the septic tank.  Add other needed material likely with a loader  Heat the tank with solar to start it out running in the less gas efficient mode to begin with but sterilizing the fecal coliform etc out of it by taking it to 150 degrees for a few days.  Let it cool to run in the more efficient lower range till done producing gas.  When the batch is done pressure it up with air and push the tank's contents out for use on other locations.  If the whole tank gets to 150 degrees for several days the dangerous to humans bacteria will be killed while the high temp methane bacteria will survive.

There is actually an Australian company marketing a digester. I put details on the site a while ago.

John your link isn't going where you think.  Suggest editing and resetting it.