Let's agree on definitions!* Onsite systems are susceptible to malfunctions of two main types: 1. functional malfunctions and 2. performance malfunctions. * A functional malfunction mal·func·tion v. 1. To fail to function. 2. To function improperly. n. 1. Failure to function. 2. Faulty or abnormal functioning. prevents the onsite system from operating as planned or designed. * Symptoms that might indicate such malfunctions include -- excessive septage sep·tage n. The waste content found in a septic tank. pumping, -- surface breakout, -- plumbing plumbing, piping systems inside buildings for water supply and sewage. The Romans had a highly developed plumbing system; water was brought to Rome by aqueducts and distributed to homes in lead pipes—hence the name plumbing from the Latin word plumbum backup, and -- direct discharge. * Functional malfunctions have implications for public health. * Performance malfunctions cause the septic septic /sep·tic/ (sep´tik) pertaining to sepsis. sep·tic adj. 1. Of, relating to, having the nature of, or affected by sepsis. 2. system to inadequately treat wastewater. * Symptoms of such malfunctions include -- excessive nutrient nutrient /nu·tri·ent/ (noo´tre-int) 1. nourishing; providing nutrition. 2. a food or other substance that provides energy or building material for the survival and growth of a living organism. (nitrogen and phosphorous phos·pho·rous adj. Of, relating to, or containing phosphorus, especially with a valence of 3 or a valence lower than that of a comparable phosphoric compound. ) release to groundwater and surface waters; and -- inadequate bacterial treatment, which may result in bacterial degradation of surface-water and groundwater quality. * Performance malfunctions have implications for water quality and possibly for public health. * The use of the term "septic-system malfunction rate," or sometimes "failure rate," has been inconsistent in the industry and has caused confusion. * The article proposes the following definitions: -- Annual malfunction rate is the number of annual malfunctioning mal·func·tion intr.v. mal·func·tioned, mal·func·tion·ing, mal·func·tions 1. To fail to function. 2. To function improperly. n. 1. Failure to function. 2. septic systems divided by the total number of septic systems in the study area during a 12-month period. -- The percentage of septic systems in malfunctioning status is the number of septic systems that are in malfunction condition at one time divided by the number of systems in the study area. * The annual malfunction rate is a critical component in cost-effectiveness analysis cost-effectiveness analysis Cost-utility analysis Clinical trials A form of economic analysis in which alternative interventions are compared in terms of the cost per unit of clinical effect–eg cost per life saved, per mm Hg of lowered BP, per yr of . * It is a way of stating economic useful life. * In sewerage sewerage, system for the removal and disposal of chiefly liquid wastes and of rainwater, which are collectively called sewage. The average person in the industrialized world produces between 60 and 140 gallons of sewage per day. systems, treatment plants generally have an economic life of 20 years and sewers of 60 years. * Sewers can represent 60 percent of the cost of the sewerage system. * So a weighted average for the useful economic life of sewerage systems is approximately 44 years. * When the capital cost for onsite systems is similar to that of sewers, the onsite systems need to have an economic life of at least 40 years to be cost-effective. * When onsite systems are less expensive than sewers, they can have an economic life of less than 40 years and be cost-effective. * Thus, communities with annual failure rates in the range of 1 to 3 percent per year have economically attractive and sustainable wastewater management systems. * The percentage of septic systems in malfunction status is an indication of how severe the onsite wastewater situation is in a community. * If this value exceeds approximately 15 to 20 percent, the community is likely at serious risk from the standpoints of public health, water quality, and economics. * The authors suggest that in general, the percentage of septic systems in malfunction status should not exceed approximately 5 to 10 percent. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion