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 Lateral Movement of Water in the Capillary Fringe Under Drainfields
Aziz Amoozegar
Item Number: NRL2006AC-3
Shipping Weight: 0lbs. 0oz.
Price: $20.00
In a septic system wastewater is dispersed in the soil through a drainfield to receive treatment before entering ground or surface waters. In order for a septic system to function properly, all the wastewater applied daily to the trenches of the system must infiltrate the soil and move away from the drainfield area within each 24-hour period (Amoozegar et al., 2005). In the absence of a water table, wastewater that infiltrates the soil from the trenches (or drip lines, if applicable) moves vertically down through the unsaturated zone until reaching an impermeable or slowly permeable layer. With continuous use of the system, a zone of saturation is formed before water moves laterally away from the system. Depending on the properties of the impermeable or slowly permeable layer, the zone of saturation may grow laterally until reaching a drainage outlet. When a water table is present, it is assumed that wastewater that percolates vertically down through the unsaturated zone enters the saturated zone below the water table before moving laterally with the ground water. Based on this assumption, ground water samples are generally collected from various depth intervals below the water table using sampling wells or piezometers for monitoring transport of pollutants from septic systems (or any other land-based waste management system). This practice, however, may not yield the correct information as the capillary fringe above the water table may impede vertical movement of percolating water. The objective of this laboratory study was to evaluate water movement from simulated septic system trenches in the unsaturated zone and through the capillary fringe in a homogeneous sandy soil with a shallow ground water.