Blackwater mercenaries seize town

Posted by Mark on November 13, 2010, 9:36 am
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WHAT IS WASTEWATER? Wastewater, or sewage, is generated through the use of toilets, bathroom sinks, showers and bathtubs, kitchen sinks, garbage disposals, dishwashers and washing machines. The average person produces about 50 to 75 gallons per day of wastewater. The wastewater contains dissolved organic and inorganic materials, suspended and settleable solids, and microorganisms, including bacteria and viruses. Direct discharge of wastewater to surface waters, groundwater, or ground surfaces will result in public health hazards. To protect the environment, the majority of unsewered homes utilize septic tanks to remove solids and greases, and leach fields, or other types of soil absorption systems, for wastewater disposal. HOW DO SEPTIC TANKS WORK? In the past, wastewater treatment and disposal facilities for homes with indoor plumbing consisted of buried bottomless containers, or cesspools. Discharge of both solids and liquids to the soils caused the soil pores to clog, and contaminated water entered surface waters and groundwater. Therefore, to protect the soils and reduce public health hazards, septic tanks were installed between the houses and the soil absorption systems. Septic tanks are watertight containers which remove large solids and greases, provide anaerobic digestion of the solids, and storage of the sludge and scum. Septic tanks do not remove large numbers of bacteria and viruses. Septic tanks are constructed of concrete, bricks, clay, or fiberglass. Baffles are placed within the tank to improve solids settling and prevent the scum layer of lightweight solids, fats and greases from floating out of the tank with the effluent. The settled solids are biologically digested by bacteria which live in environments without air (anaerobic bacteria). Some of the products of anaerobic digestion are gases, including methane, carbon dioxide, and hydrogen sulfide, which has an odor similar to that of rotten eggs. The gases are vented from the septic tank through the household plumbing vents. Inorganic and non-biodegradable materials cannot be digested by the microorganisms in the septic tank, and accumulate in the sludge or digested by the microorganisms in the septic tank, and accumulate in the sludge or scum layers. The sludge and scum layers must be removed periodically to prevent the accumulated solids and greases from flowing into the soil absorption system and clogging the soil pores. If washing machines, dishwashers, and garbage disposals are used, the amount of sludge will increase and the septic tank will require frequent cleaning. WASTEWATER DISPOSAL BY SOIL ABSORPTION Effluent from the septic tank flows by gravity or is pumped to a leach field for disposal. The wastewater effluent is absorbed by soil particles and moves both horizontally and vertically through the soil pores. The dissolved organic material in the effluent is removed by bacteria which live in the top ten feet of the soil. As the effluent moves through the soil, the temperature and chemical characteristics of the wastewater change and create an unfavorable habitat for most bacteria and viruses. Therefore, as the septic tank effluent moves through the soil, organic material and microorganisms are removed. The wastewater generally percolates downward through soil and eventually enters a groundwater aquifer. A portion of the wastewater moves upwards by capillary action and is removed at the ground surface by evaporation and transpiration of plants. A leach field consists of a series of four-inch diameter perforated distribution pipelines placed in two-to-three foot wide trenches. The perforated pipe is placed on top of gravel which is also used to backfill around the pipe. The gravel promotes drainage and reduces root growth near the pipeline. Untreated building paper or straw is placed over the gravel to prevent fine soil particles from migrating into the gravel. The building paper or straw does not reduce the evapotranspiration of the wastewater. A minimum topsoil cover is placed over the gravel to protect the leach field, prevent contact with the wastewater and reduce infiltration from rain and snow. HOW DO SEPTIC SYSTEMS FAIL? When sewage collects on the ground surface or seeps from the side of a bank, or when the household plumbing becomes clogged, you are probably experiencing a septic system failure. Although the failure may be caused by the septic tank, usually it is the leach field which has failed. Leach field operation is affected by the soil percolation rates. To ensure that the sewage is treated adequately, in the soil, minimum separation distances have been established between leach fields, fractured bedrock, groundwater, streams, cut banks, wells, water supply pipelines, houses, and property lines. When adequate soil depth is not available, untreated sewage seeps from s·ides of sloping cut banks,--enters streams, or contaminates groundwater. To prevent such failures, specific design criteria should be used for septic systems in areas with bedrock and/or steep slopes. These areas in El Dorado County include lands along the south fork of the American River, lands to the southeast of Somerset, and lands to the southeast of Latrobe. The most frequent cause of sewage ponding on the ground or clogging of household plumbing is reduction of soil percolation rates. Percolation tests should be completed on the leach field site prior to construction. The percolation rate is used to calculate the amount of sewage which can be applied per square foot of leaching area. If the percolation rate is slow due to clay particles in the soil, a larger leach field is needed than if the soil consisted of sand and gravel. Portions of El Dorado County which may require larger leach fields due to clay soils include Pollock Pines, Sly Park, land south of Placerville, Diamond Springs and Shingle Springs. As the leach field becomes older, a bacterial slime mat grows in the soil under the trench. The mat functions as part of the wastewater treatment process, however, the mat also reduces the percolation rate. Percolation rates are also reduced by solids which flow from septic tanks that have not been pumped and by flooding due to high groundwater or sewage flowing from neighboring leach fields.

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