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Fact and myth about your on-farm septic system

Fact and myth about your on-farm septic system
Local official fields questions about on-farm septic systems.

Farmers and homeowners alike had questions for Randy Pease when the Johnson County Homesite program was presented at Franklin High School recently. Pease works with septics and soils with the Johnson County Health Department.

Question: I've heard it's better to have septics on well-drained, even gravelly soils like Ockley or Fox Soils with gravel underneath. Doesn't that let too many nitrates filter into the groundwater below?

Septic answers: Randy Pease explains answers to questions about septic systems from farmers and homeowners.

Pease: Well-drained sites are generally good for septics. It is true that on gravelly soils if the gravel is very close to the surface, things can flow through too quickly and harmful organisms and nitrates that the soils is supposed to filter out might not be filter out. You need some regular soil in the first few feet to make the system work. Lines may be placed at more shallow depths in those soils. If there is a reasonable amount of soil before gravel begins, it can still work.

Question: Our system was approved and works well for the most part. We have three fingers. Sometimes the ground is more moist over a flat spot on one of the fingers. It doesn't smell. What is going on?

Related: Farm Septic System Fix

Pease: It sounds like effluent is coming up near the surface there. Perhaps the pipe isn't as deep there. If a system has failed, it won't be removing the materials that cause odor. If you don't have odor then it is still being filtered out at some point.

Question: I bought a house 30 years ago and I eventually had to replace the septic system. The installer told me the old system was three or four feet deep – too deep to work. Why was a system put in that deep?

Pease: At one time that was the accepted practice. The theory was that the deeper the better, so effluent would filter down instead of up. What we've learned since is that many soils, particularly Miami soils, have dense layers. If you are in or below the dense layer, effluent can't move downward. What we need to do instead is place lines in gravel at a more reasonable depth. That's how systems are put in today.

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