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18 U.S. DEPARTMENT OF AGRICULTURE PAGE 2 OF 3 NATURAL RESOURCES CONSERVATION SERVICE 10/30/00 9ANITARY FACILITIES Endnote -- SANITARY FACILITIES This report shows khe degree and kind of Boil limitation6 Chat affect septic tank absorption fields, sewage lagoons, and saniCary landfills. The 1lmitakiona are considered "811ght" if soil properties and Bike features generally are Favorable for the indicated use and limitations are minor and easily overcome; "Moderate" if soil properties or site feakurea are not favorable fox Che indicated use and special planning, design, ar maintenance is needed to overcome or minimize Che limitations; and "Severe" if Boil properties or site features are so unfavorable or so difficult to overcome thaC special design, signifieanC increases in conakrucCion coats, and possibly increased maintenance are required. This report slap shows Che suitability of the soils for use as daily cover Por landfills. A rating o! "good" indicates thaC soil properties and site features are favorable for Che use and good performance and low maintenance can be expected; "Fair" indicates that soil properties and site feakuxes are moderately favorable for Che use and one or more soil properties or site feaCUres make Che soil lees desirable Chan the soils rated "Good'; and "Poor" indicates ChaC one er more soil properties or site features are unfavorable for Che use and overcoming Che unfavorable properties requi'rea special design, extra maintenance, or costly alCeration. SEPTIC TANK ABSORPTION FIELDS are areas in which effluent from a'eeptic Lank is distributed into Che soil through subsurface tiles or perforated pipe. Only Chat part of Che soil between depths of Sa Co 72 inehee is evaluated. The ratings are base on soil properties, site feaCurea, and observed performance o! the eoile. Permeability, a high wafer Cable, depth to bedrock or to a cemented pan, sad flooding affect absorption o! the effluenC. Large atones and bedrock or a cemented pan interfere with installation. Uneatiafactory performance of eeptio Cask abaorpCioa Fields, including excessively slow absorption of effluent, surfacing of elfluenC, and hillside seepage, can affect public healCh. GroundwaCer can 'be polluted if highly permeable sand and gravel or fractured bedrock is lase than 4 feeC below the base a! Che absorption field, if elope is excessive, or if the water Cable is near the surface. There moat be unsaCurated soil material beneaCh the abeorpkioa.field to filCer Che eflluenC effectively. Macy local ordinances require Chat this material be of a certain thickness. SENAGE LAGOONS are shallow ponds constructed Co hold sewage while aerobic bacteria decompose Che solid sad liquid wastes. Lagoons should have a nearly level floor 9+•~+^~•^~ed by CLiC slopes or embankmenCa of compacted soil. Lagoons ' generally are designed Co hold Che sewage within a depth of Z to 5 feet. Nearly impervious soil material far the lagoon floor and aides is required to minimize seepage and costaminatioa of ground water. This report gives xaCings for Che natural soil Chat makes up the lagoon floor. The surface layer and, generally, i or ~ feeC of soil material below the surface layer are excavated Co provide material for Che emban]aoenCe. The ratings are based on soil properties, siCe features, and observed performance of'the voila. Considered in Che raCinge are slope, pexmeabiliCy, a high waken table, depth Co bedrock or tp a cemented pan, flooding, large atones, and coriCeriC of organic matter. Excessive seepage due to rapid permeability of Che soil or a water Cable that is high enough to raise the level of sewage in the lagoon causes a lagoon Co function ussaCisfacCOrily. Pollukion results if seepage is excessive or if floodwater overkope Che lagoon. A high contest of organic matter is detrimental to proper functioning of Cha lagoon because it inhibiCa aembic activity. Slope, bedrock, and cemented pans can cause construction problems, and large skones can hinder compaction of the lagoon floor. SANITARY LANDFILLS are areas where so11d waste is disposed of by burying iC in soil. There are two [ypee of landfill, trench and area. In a trench landfill, Che waste is placed is a trench. IC is spread, compacted, and covered daily wiCh a Chin layer of soil excavated at the site. In an area landfill, Che wasCe is placed in successive layers on Che surface of Che Boil. The wasCe ie spread, compacted, and covered daily with a thin layer of soil farm a source away from the site. ,Hoch types of landfill must be able to bear heavy vehicular traffic. Both types involve a risk of groundwater polluCion. Ease of excavation and revegetation need to be considered. The ratings in this report are based