For septic tanks in Northern Virginia to drain and treat effluent effectively, their drainfield soil needs to have certain properties, and there needs to be some erosion control on and around the drainfield.
Drainfield soil is assessed by:
- Texture: This allows us to estimate pore sizes in the soil. The field method is ‘texture by feel’ in which a flow chart is used as the soil is manipulated by hand.
- Structure: This is the naturally occurring aggregation of particles into a larger form, often called a ped. Unless the soil is structureless, it tends to break up into these peds. These structures can play a role in porosity and water movement within the soil.
- Density: This also has an effect on the porosity of the soil, in turn affecting its permeability. The more compact the soil is, the less permeable it becomes. The field test is performed by probing the soil with a rod. This gives a very general estimate as to its compaction/density.
- Color: The color of soil and soil layers can indicate whether it has good/poor drainage. In general, if drainage is good it is typical to for the soil to have bright colors and clearly defined soil layers. Dull/grey colors and mottles appear in poorly drained soils, although may not always be an indicator of saturated soils or seasonal water tables. These colors are controlled by redox reactions and translocation of C, Fe, Mn, and S compounds in the soil.
To manage soil erosion:
- If you have a sump pump, make sure it’s directed away from the drainfield.
- Rainfall running off roofs or concrete areas should be drained around the drainfield to prevent the field from filling with water.
- Never drain a pool or jacuzzi near the drainfield.
- Correct any depressions in the drainfield where surface water might collect (watch for puddles after a rain, and fill those areas in.)
- Add herbaceous, shallow-rooted plants such as flowering perennials and annuals, turfgrass, other groundcovers keep soil from puddling on or eroding the drainfield. (Be careful not to dig too deep – septic tank drain lines are buried only 2 feet deep.)
For more information about septic tanks in Northern Virginia, please contact the experts at SES Mid Atlantic, LLC. Based in Warrenton, Virginia, SES has provided expert septic system inspections, service, maintenance and repairs to Northern Virginia systems since 1987.