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Septic Tank Absorption Fields— orange County, North Carolina <br />Description <br />Septic tank absorption fields are areas in which effluent from a septic tank is <br />distributed into the soil through subsurface tiles or perforated pipe. Only that part <br />of the soil between depths of 24 and 60 inches is evaluated. The ratings are based <br />on the soil properties that affect absorption of the effluent, construction and <br />maintenance of the system, and public health. Saturated hydraulic conductivity <br />(Ksat), depth to a water table, ponding, depth to bedrock or a cemented pan, and <br />flooding affect absorption of the effluent. Stones and boulders, ice, and bedrock or <br />a cemented pan interfere with installation. Subsidence interferes with Installation <br />and maintenance. Excessive slope may cause lateral seepage and surfacing of the <br />effluent in downslope areas. <br />Some soils are underlain by loose sand and gravel or fractured bedrock at a depth <br />of less than 4 feet below the distribution lines. In these soils the absorption field <br />may not adequately filter the effluent, particularly when the system is new. As a <br />result, the ground water may become contaminated. <br />The ratings are both verbal and numerical. Rating class terms indicate the extent <br />to which the soils are limited by all of the soil features that affect the specified use. <br />"Not limited" indicates that the soil has features that are very favorable for the <br />specified rase. Good performance and very low maintenance can be expected. <br />"Somewhat limited" indicates that the soil has features that are moderately <br />favorable for the specified use. The limitations can be overcome or minimized by <br />special planning, design, or installation. Fair performance and moderate <br />maintenance can be expected. "Very limited" indicates that the soil has one or more <br />features that are unfavorable for the specked use. The limitations generally cannot <br />be overcome without major soil reclamation, special design, or expensive <br />installation procedures. Poor performance and high maintenance can be expected. <br />Numerical ratings indicate the severity of individual limitations. The ratings are <br />shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations <br />between the point at which a soil feature has the greatest negative impact on the <br />use (1.00) and the point at which the soil feature is not a limitation (0.00). <br />Rating Options <br />Aggregation Method: Dominant Condition <br />Component Percent Cutoff. None Specified <br />Tie -break Rule: Higher <br />Natural Resources Web Soil Survey 2.0 <br />conservation Service National Cooperative Soil Survey <br />5/8/2008 <br />Page 4 of 4 <br />