Department of Food, Agricultural and Biological Engineering

Articles Contributed to Ohio's Country Journal  
Mid-February 2004

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Ohio's Country Journal

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January -  2004

Applied Engineering

Don’t Assume You Can Install a Septic System
Karen Mancl

If you are planning to build a home out in the country, first check to see how what is needed to safely treat and dispose of the household wastewater.  More and more home builders are surprised to learn that a home site is not suited for a septic system.

Safe treatment and disposal of wastewater requires a deep layer of unsaturated, permeable soil.  After digging absorption trenches about 18 inches deep, an additional four feet of unsaturated soil must be available year-round to remove pollutants and pathogens from sewage.  With the soil does an excellent job of removing pollutants to protect wells and Ohio’s streams, only 6.4% of the land area of Ohio have soils deep enough to completely treat wastewater with a conventional septic system.

You can take 3 steps to make sure a lot is suited for a septic system before investing in home construction.

1. Find the lot on the local soil survey map available at no cost from the USDA Natural Resources Conservation Service.  Check with the local Soil and Water Conservation District or OSU Extension office to find a map for the area.  The map outlines the predominant soil on the lot and includes descriptions of the soil and expected small areas of included soil types.
2. Compare the soils on the lot to those suited for septic systems listed in Suitability of Ohio Soils for Treating Wastewater. Extension Bulletin 896 available at Ohio county Extension offices or at www.ag.ohio-state.edu/~setll
3. Hire a professional soil scientist to evaluate and map the site to identify the best spot for septic system.  Once identified, protect the area with a fence to keep construction traffic, piles of fill and building materials, and excess surface drainage off the site.  A list of soil scientists that have completed the OSU Onsite Wastewater Treatment System Design School are posted on the same website as the Extension Bulletin 896.

If the site is not suited for a septic system, alternative systems can be constructed, however, they cost more to install and require more maintenance.  Extension Bulletin 896 goes on to list all of Ohio’s soil types and suggests wastewater treatment and disposal systems suited to each soil type.  The website posts manuals for mound, sand bioreactor, and irrigations systems as well as lists of contractors and designers that have taken OSU workshops to learn how to design and install these alternative systems.

To find Suitability of Ohio Soils for Treating Wastewater. Extension Bulletin 896, other manuals or lists of people with expertise in onsite wastewater treatment check the website for the OSU Soil Environment Technology Learning Lab  www.ag.ohio-state.edu/~setll

 Figure 1.  A sand bioreactor being constructed on a lot not suited for a septic system.

This column is provided by the OSU Department of Food, Agricultural, and Biological Engineering.