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A percolation test (colloquially called a perc test) is a test to determine the water absorption rate of soil (that is, its capacity for percolation) in preparation for the building of a septic drain field (leach field) or infiltration basin. [1] The results of a percolation test are required to design a septic system properly.
From figure 1 it is seen that 800 mm of water (or 8000 m 3 /ha) is required to bring the soil salinity down to 60% of its original value in the soil layer at 40 to 60 cm depth. When the salinity must be less than 60%, extrapolation of the leaching curve, the use of a leaching equation (see below) or a leaching model like SaltMod is necessary to ...
A soil family category is a group of soils within a subgroup and describes the physical and chemical properties which affect the response of soil to agricultural management and engineering applications. The principal characteristics used to differentiate soil families include texture, mineralogy, pH, permeability, structure, consistency, the ...
For a given soil, the greater the void ratio, the higher the value of the coefficient of permeability. Here 'e' is the void ratio. Based on other concepts it has been established that the permeability of a soil varies as e 2 or e 3 /(1+e). Whatever may be the exact relationship, all soils have e versus log k plot as a straight line. [2]
Coarse soils – sand and gravel – can transmit wastewater away from the drain field before pathogens are destroyed. Silt and clay effectively filter out pathogens but limit wastewater flow rates. [3] Percolation tests measure the rate at which clean water disperses through a disposal trench into the soil.
The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt):
These soils have a very slow rate of water transmission (final infiltration rate less than 0.05 in (1.3 mm) per hour). Selection of a hydrologic soil group should be done based on measured infiltration rates, soil survey (such as the NRCS Web Soil Survey), or judgement from a qualified soil science or geotechnical professional. The table below ...
the discharge rate (Q) from the recharge rate (R) in a water balance as detailed in the article: hydrology (agriculture) the permissible long term average depth of the water table (Dw) on the basis of agricultural drainage criteria; the soil's hydraulic conductivity (Ka and Kb) by measurements; the depth of the bottom of the aquifer (Di)