Soil Considerations for Utilization of Drip Dispersal in Tennessee Division of Ground Water Protection TN Department of Environment and Conservation

Soil soil - Soil is a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment.

Soil to a civil engineer:  Regolith, or any earthen material that can be removed without blasting

“Soil”, to some, is a punk rock band…

For the purpose of permitting drip:  Extra High Intensity Map  20 inches minimum depth to restrictive layer  Pit Profile Descriptions 2/acre  Examining Soil’s Texture and Structure  Arrive at Loading Rate

Drip Dispersal Technology  Opens the window slightly:  Heavier clays  Shallower depth to bedrock and other restrictive layer, i.e. fragipan  Footprint considerations

Shallow Drip Dispersal  Shallow, 8 inch installation depth  12 inch buffer  Uniform distribution  Slow application  Evapotranspiration  Root zone uptake  Treated effluent

Soil Texture

Soil Structure

Example Silty clay, blocky, weak =.075 gpd/ft2 3 bedroom home : 150 gpd x 3 = 450 gpd 450/.075 = 6,000 ft2 for initial system 100% duplication area required Total of 12,000 ft2 of suitable soil necessary

Example Silt Loam, blocky, moderate =.3 gpd/ft2 3 bedroom home : 150 gpd x 3 = 450 gpd 450/.3 = 1,500 ft2 for initial system 100% duplication area required Total of 3,000 ft2 of suitable soil necessary

Example Considering a typical Dickson soil profile with a 75 mpi rate: Conventional – 370 ft2/bdrm x 3 bdrm = 1110 ft ft2/3 foot wide trench = 370 linear feet 370 linear feet x 10’ = 3,700 ft2 x 2 = 7,400 ft2 LPP – 450 gpd/0.15 gpd/ft2 = 3,000 ft2 x 2 = 6,000 ft2 Drip – 450 gpd/0.3 gpd/ft2 = 1,500 ft2 x 2 = 3,000 ft2

Why Not Fill Material ?

How do we drain certain soils for drip dispersal purposes ??  Depth of drainage improvement  Depth at which wetness mottles are encountered  Depth to restrictive layer  Position in landscape  Positive outlet  Buffer zone requirements  Drainage improvement placed within permitted soil(s)

Questions ?