Agenda - 10-08-1991 - Laserfiche WebLink

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It is important to note here that conventional, alternative, and other "soil based" systems are not a permanent solution. Eventually all these systems will fail when the absorbing and treatment capacity of the soil is reached. A properly sited and constructed system can be expected to function anywhere from 15 to 30 years depending on many variables. Advantages to conventional septic systems are adequate treatment of domestic type wastes, low construction cost, low maintenance requirements and costs. Disadvantages to conventional septic systems are requirements for the best and deepest soils to operate effectively and difficulty in repairing or reconditioning systems which have failed. Failure of conventional systems generally results in untreated effluent surfacing, running into surface waters, or entering shallow ground water. Class 11 System - Individual Pump Systems - The individual pump system is very similar to the individual conventional system, but is generally referred to as an alternative system. In these systems, septic tank effluent flows into a pump tank and is pumped to the nitrification field. In the pump conventional system, the effluent-is pumped to a nitrification field which is identical to that of the conventional system. The pump is required because the suitable soils are located on land higher than or remote from the residence and effluent cannot flow to the nitrification field by gravity. A second type of pump system is the low pressure pipe system. It has a n trification field that is constructed differently than a conventional system. The low pressure distribution lines are small diameter plastic pipes with regularly spaced holes installed in 10" gravel trenches. There are usually five or more lines up to 70 feet in length in the nitrification field. Each of these lines is dosed with effluent at a design rate and discharges effluent into the trench along - -the entire length. LPP trenches are installed shallower than conventional trenches and form a clogging mat more slowly but more extensively than conventional systems. There are several advantages to pump systems. Nitrification fields do not have to be located in areas near or lower than the building using them. Low pressure nitrification fields can be used in shallower soils than is allowable for conventional nitrification fields. There is an additional advantage in that the effluent is distributed evenly throughout the entire drainfield, thus minimizing the effect of a " progressive failure " as described in the conventional system section. This feature also helps to maintain the desired aerobic conditions in the trench. There are also a' 5