Estimation of Saprolite Thickness Needed to Remove E. coli from Wastewater

Saprolite, weathered bedrock, is being used to dispose of domestic sewage through septic system drainfields, but the thickness saprolite needed remove biological contaminants unknown for most saprolites. This study developed and tested a simple method estimating below drainlines filter E. coli from wastewater using estimates volume pores that are smaller than length coliform (≤10 μm). Particle size distribution (texture) water retention data were obtained 12 different saprolites Piedmont Mountain regions North Carolina (N.C.). Saprolite textures ranged clay loam coarse sand. The with diameters ≤10 μm determined by measurements each saprolite. in an equation estimate coli. estimated thicknesses 36 cm 113 average across all samples was 58 cm. increased as silt percentage decreased sand situ saturated hydraulic conductivity increased. Silt may be useful appropriate field.