Septic Perc Test & Soil Testing in Saline County, Kansas

A percolation test measures how quickly water soaks into the soil at the depth a drain field will sit. Holes are dug or bored at the proposed field location, saturated, and then the rate at which the water level drops is measured. That rate, together with a look at the soil profile itself, is what a system design is built on.

You need one when you are building on raw ground, when you are replacing a failed system and the original design is unknown or no longer adequate, and when you are adding enough load to a property that the existing field will not carry it. If you are buying bare land with the intention of building, a perc test before you close is one of the most useful few hundred dollars you can spend, because a property that will not perc is a very different property than the one you thought you were buying.

The test also establishes where the field can go, which has knock-on effects on the whole site plan. Setbacks from the well, the house location, the driveway and any future shop all get easier to place once you know where the field has to be.

Heavy clay drains slowly. A slow perc rate does not necessarily mean no system; it usually means a larger field, a different layout, or in some cases an engineered or alternative system rather than a conventional one. What it always means is that guessing the field size is a bad idea, because a field undersized for clay will fail and it will fail in a way that cannot be repaired cheaply.

Rocky and limestone ground is the other end of the problem. Shallow bedrock limits how deep a field can go, and fractured rock can move water too quickly to treat it properly, which is a groundwater issue as much as a performance one. Both conditions exist within short distances around here, which is why a test on the actual proposed field location matters more than a general idea of what the area is like.

We have put systems in across enough of this ground in Saline, Ottawa, Lincoln, Dickinson, Ellsworth and Cloud counties to know which questions to ask before anyone starts digging. The blog posts linked below go through the clay and rocky-ground cases in more detail.

• Site walk and discussion of where the field could reasonably go
• Test holes dug or bored at the proposed drain field location
• Soil profile assessment, including depth to rock or restrictive layer
• Percolation rate measurement
• Well, property line and structure setback considerations
• What the results mean for system type, field size and layout
• County health department coordination for the permitting process