Warrenton VA Perc Test: Perc Test 101

Perc Testing

A percolation test (known as a “perc” test) assesses whether the area that is to be designated as a drain field (or leach field) is able to absorb effluent from a septic system. It’s a make or break test that could make the difference on whether one can even build house on a rural property in Warrenton VA. Perc testing determines whether a septic system can be viable on that land. If the site fails the perc test, then a traditional septic system cannot be built.

Basically, a perc test evaluates the soil’s absorption ability. Most soils contain some combination of gravel, sand, clay and solid rock. Gravel and sand drain better than clay and solid rock. The more clay or solid rock, the more likely the soil will fail the perc test. Testing requirements will vary from town to town. You’ll want to work with a local company like SES that understands the requirements in Warrenton VA. Perc test results record drainage characteristics of the soil as well as the speed or rate at which water drains (or “percolates”) through the soil.

Most tests start with a deep hole test. A machine is used to dig a hole about 7 to 10 feet below the proposed drain field area. Soil will be visually assessed and possibly sent to a lab for analysis. The inspector is looking for the presence of water, the height of the water table, soil types and conditions, and the amount of nonabsorbent rock.

To test the absorbency or percolation rate of water, generally several holes about two feet deep are dug approximately 4 to 6 feet apart from each other. Each hole, which is about 6 to 12 inches in diameter, is then filled with about 2 inches of sand or gravel and presoaked overnight. If the presoak fill has more than 6 inches of water remaining by morning, it’s an automatic fail in Warrenton VA. Perc test results can continue to be collected if the presoak was absorbed. Six inches of water are then added and a measurement is taken each 30 minutes over a 4 hour period to calculate the water absorption rate. There are a number of nuances to this test that SES can tell you about. Contact us to walk you through the process and to provide you a quote.

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