Jim and Dave Go Back To the Basics One More Time

The industry has advanced greatly in our time, but the principles of good onsite system design remain unchanged

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It doesn’t seem possible, but we have worked together conducting workshops, presenting at conferences and, for the last 20 years, written this column together. Everything eventually comes to an end. This will be the last Basic Training column we do together.

Over 30 years, we have seen and been a part of the industry making great strides on all fronts. Equipment and technologies have changed significantly. Professionalism on the part of technicians, sales personnel and government officials has increased dramatically. There is now a broad range of new products covering all aspects of our systems. In general, they are easier to use and more technical in nature. The speed of adoption of new products and technology across the board has been impressive.

While all of this is true, we still rely on the soil for the final treatment and dispersal of effluent. The single most common mistake on the part of installers in general is the misinterpretation of the soil they are working with. Therefore, we thought it would be appropriate to leave where we started, with the three most important principles to good drainfield installation. Some of you should know these by heart. If this is your introduction to them, remembering them will help you avoid a lot of problems in the future.


The principles we refer to are KILL (keep it level _), KINN (keep it natural _) and, KISS (keep it shallow_). The final letter in the principles as it always has been is left for you to creatively fill in!

Keep it level refers not only to keeping sewage treatment trenches and the top of the treatment media level; but it means installing sewage tanks on the level and at the proper orientation. Nothing should be eyeballed in; it should be carefully planned and laid out with differences in elevation noted before the first scoop of soil is excavated.

To this day, while troubleshooting systems, we see where trenches have not been maintained on the contour. One note here: piping between system components should be laid on the proper slope. To ensure level components and proper pipe slopes requires use of a level.

Keep it natural refers to using undisturbed soil for installation of the final treatment and dispersal area, whether that involves below- or above-ground treatment units. It means protecting the soil treatment area from pre-installation disturbance and taking care during installation to not cause compaction or smearing during trench excavation. It means keeping the proper separation distance from any regional or seasonal high water tables.

In the case of mounds and at-grades, it means keeping the original soil surface intact. The original soil surface should not be removed and saved for future topsoil use but left in place with the green side turned down. The soil surface in general is the most permeable and best treatment part of the soil and should be utilized as such.

It also means not working the soil when it is too wet. The moisture content of the soil at the depth of excavation or scarification needs to be less than the plastic limit. This can be determined in the field by attempting to roll a palm full of soil into an 1/8-inch ribbon. If a ribbon can be formed, don’t dig!

Keep it shallow refers to maintaining proper vertical separation distances from any limiting soil conditions. Examples of limiting conditions include high water tables, bedrock and dense soil layers. Being able to recognize these conditions is important to proper location and elevation of the soil treatment area. Being able to recognize soil features indicating periodic saturation and differences in permeability are important skills for installers, site evaluators and government officials. Recognizing and understanding redoximorphic features is a key part of identifying wet soils and setting depths of excavation.

If you are uncertain about your interpretation, find a soil scientist to help. Keeping it shallow also means installing the system close to the surface in the most permeable and biologically active soil horizons to maximize the ability of the soil to accept and treat sewage effluent.


If you pay attention to these basic principles, you will become known as the installer to go to in your area for long-lasting systems.

We would be remiss if we did not thank everyone at COLE Publishing for allowing us to write these columns. The editors and other personnel have been great to work with all these years. Hopefully we will still see each other from time to time in the future. And lastly, thanks to the readers for continuing to take an interest in Basic Training.  


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