A Percolation Test is a test TDEC requires on certain soil series that were identified by a High Intensity Soils Map.  TDEC will require a Percolation Tests if the site meets any one of these conditions:

1. The site contains soil series that are required to have percolation tests to determine the suitability based on TDEC’s Regulations to Govern Subsurface Sewage Disposal Systems. The High Intensity Soils Map will detail the soils that require these tests and why.  Typically, these will be sites that have soils very heavy in clay or shale soils. 

Percolation Tests are a 2-day process which measures how quickly water drains into the soil at a known depth.  Typically, post holes are used that are no smaller than 6 inches and no larger than 12 inches.  Each hole will be placed 50 feet apart in the soil unit.  These holes are usually 30 inches deep.  2 inches of gravel will be placed in the bottom of the hole and presoaked with 12 inches of water for 24 hours.  After 24 hours, the tests will be 6 inches of water and measured every 30 minutes for 4 hours while maintaining the 6 inch water level.  The data will be recorded and shown on the percolation test report.  To complete this map, we will need the following:

1. All lot corners marked and numbered or grid staked.
2. The completed High Intensity Soil Map.

Our deliverable will be TDEC’s Report of Absorption Test and a map showing the percolation test sites.  These tests do not guarantee approval through TDEC.