When you’re looking at buying land, there’s one question burning in the minds of everyone from the broker to buyer…
“Will it perc?!?”
It’s the single question that can render a potentially valuable piece of land almost worthless. The seller will tell you it will. The broker will say that it might, but one thing’s for sure, you need a good perc if you’re planning to build. So what the heck is a perc test?
A percolation test is simply a test for measuring the soil’s ability to absorb water. In order for a septic tank to work, the soil has to be able to disperse the water that is pushed into the system at a faster rate than it comes in. If soil don’t perc, the tank won’t work. Thank you, Johnny Cochran.
In most rural areas the water company won’t give you service without a septic tank (or sewer). They require you to file for a permit (translated “$200 tax” in St. Clair County), and then an inspector verifies that the system is designed and installed correctly, so it won’t belch sewage all over your neighbors, pets and loved ones. Once everything is in place, you’re cleared for water service which will cost another $700 as a “tap fee” in St. Clair County. They literally get you with the water coming and going.
In order to get a perc test, you’ll need to hire a qualified, certified soil classifier, surveyor, engineer or geologist (we’ll call him the Soil Dude) to travel to your property and dig some holes. Your land broker, ag lender or county extension agent should be able to lead you to a certified Soil Dude.
There are several ways they can administer the test. Some will dig a big pit with a back hoe. The pit is then filled with water several times, and the time it takes to drain water is determined in minutes-per-inch. Another method involves using a hand auger to dig several 6″ diameter holes, and the Soil Dude examines the type and color of the layers to determine the perc rate scientifically.
My Soil Dude was a professional soil classifier, and he used the second method. We also had him dig several other cores near the potential pond site to determine soil classification for the pond designer, but that’s another story…
With the information from the site visit in hand, the Soil Dude retired to his soil science lair, wrote up a report and generated the necessary paperwork to be filed with the county health department.
Once the department issues a permit, a licensed installer can install the tank and field lines, which will then be inspected by the health department again to ensure that everything looks good.
So now you know.