Orange County NC Website
U.S. DEPARTMENT OF AGRICULTURE 1 <br />PAGE 2 OF 3 <br />N?"~UR.-lL RESOURCES CONSERVATIGN $SRVICE 08/9/DO <br />SANITARY FACILITIES <br />Endnote -- SANITARY FACILITIES <br />This report shows the degree and kind of soil limitations that affect septic tank absorption fields, sewage lagoons, <br />and sanitary landfills. The limitations are Considered "Slight" if soil properties and site features generally are <br />favorable far the indicated use and limitativris are minor and easily overcome; "MVderate" if soil properties or site <br />features are not favorable for the indicated use and special planning, design, or maintenance is needed to overcome or <br />minimize the limitations; and "Severe" if soil properties or site features are so unfavorable or so difficult to overcome <br />that special deaj.gn, significant increases in construction casts, and possibly increased maintenance are required. <br />This report also shows the suitability of Che soils for .use as daily cover for landfills. A rating oP "Good" indicates <br />that soil properties and site features are favorable Ear the use and good performance and low maintenance can be <br />expected; "Fair" indicates that soil properties and site features are moderately favorable for the use and one or <br />more soil properCies or site features make the soil less desirable than the soils rated "Good"; and "Poor" indicates <br />that one or more soil properties or site features are unfavorable for the use and overcoming the unfavorable <br />properties requires special design, extra maintenance, or costly alteration. <br />SEPTIC TANK ABSORFTIDN FIELDS are areas in which effluent from a septic tank iB distributed iriC4 Che soil through <br />subsurface tiles or perforated pipe. Only that part of the soil between depths of 24 to 72 inches is evaluated. The <br />ratings are base on soil properties, site features, and observed performance of the Boils. Permeability, a high <br />water table, depth to bedrock or to a cemented pan, and flooding affect absorption of the effluent. Large stones <br />and bedrock or a cemented pan interfere with installation. Unsatisfactory performance of septic tank absorption fields, <br />including excessively slow absorption of effluent, surfacing of effluent, and hillside seepage, can affect public health. <br />Groundwater can be polluted if highly permeable sand and gravel or fractured bedrock is less than 4 feeC below the <br />base of the absorption field, if slope is excessive, or if the water table is near the surface. There must be <br />unsaturated soil material beneath the absorption field to filter the effluent effectively. Nany local ordinances <br />require that this material be of a certain thickness. <br />SEWAGE LAGOONS are shallow ponds constructed to hold sewage while aerobic bacteria decompose Che solid and liquid <br />wastes. Lagoons should have a nearly level floor surrounded by cut slopes or embankments of compacted soil. Lagoons <br />generally are designed to hold the sewage within a depth of 2 to 5 feet. Nearly impervious soil maCeri.al for the lagoon <br />floor and sides is required to minimize seepage and contamination of ground water. This report gives ratings for <br />the natural soil that makes up the lagoon floor. The surface layer and, generally, 1 or 2 feet of soil material <br />below the surface layer are excavated to provide material for the embanlonents. The ratings are based on soil <br />properties, site features, and observed performance of the soils. Considered in the ratings are slope, permeability, a <br />high water table, depth to bedrock or to a cemented pan, flooding, large stones, and content of organic matter. <br />Excessive seepage due to rapid permeability of the soil qr a water table that is high enough to raise the level of sewage <br />in the lagoon causes a lagoon to function unsatisfactorily. Pollution results if seepage is excessive qr if floodwater <br />overtops the lagoon. A high content of organic matter is detrimental to proper functioning of the lagoon because it <br />inhibits aerobic activity. Slope, bedrock, and cemented pans can cause construction problems, and large stones can <br />hinder compaction of the lagoon floor. <br />SANITARY LANDFILLS are areas where solid waste is disposed of by burying it in soil. There are Cwo types oP landfill, <br />trench and area. In a trench landfill, the waste is placed in a trench. It is spread, compacted, and Covered daily <br />with a thin layer of soil excavated at the ai,te. In an area landfill, the waste is placed in successive layers on the <br />surface of the soil. The waste is spread, compacted, and towered daily with a thin layer of soil form a source away <br />from the site. Both types of landfill must be able to bear heavy vehicular traffic. Both types involve a risk of <br />groundwater pollution. Ease of excavation and revegetation need Co be considered. The ratings in this report are based <br />