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Building Factsheet id: 48 | |
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Septic Tanks 1 - Regulations, Workings, Installation, Maintenance
Regulations applying to individual wastewater systems Primarily septic tanks Mini Wastewater Treatment Plant (WWTP) and fat traps Introduction and Contents * The 1992 wastewater law * Application of the law by Maires * What is a septic tank? * How do they work? * Drawing of a septic tank * The control * The visit * Regular maintenance of your system * New and replacement installation * Products and principals The 1992 Waste-Water Law * On the 3rd of January 1992, all towns and villages in France saw their responsibilities increased. * The Maire is now responsible for every aspect of wastewater treatment, be it collective or individual. * Your Maire is directly responsible for the control and regular maintenance of your septic tank . * Because all Maires are not specialists in the field of wastewater treatment, they have in many cases appointed a syndicate or a professional body to enforce the law. They are generally known as S.P.A.N.C. (Service Public d’Assainissement Non Collectif). Application of the 1992 Waste-Water Law * The body selected by your Maire has until December 2005 to put in place a plan of action. * This plan will identify what is the best way to treat the waste-water based on population level, cost and other factors. It will also identify every single septic tank in order to control them. * This action plan must also provide a sound financial structure for the body chosen, to remain profitable whilst enforcing the law. * Many of you will have noticed that your water bill contains a line called “Redevance Service Public d’Assainissement Non Collectif”. Basically this is a charge applied by your water company to help finance the implementation of the law. The cost does vary depending on where you live. * Many of you have also been invited to attend a public information meeting organised by the body appointed to implement the new rules. * In almost every region the action plan is already in place and ‘control’ of the septic tanks has started. What Is A Septic Tank? * A septic tank is a large tank, where all the waste-water from your home is stored. There it receives very basic treatment. * The initial concept was to create an environment that was both aerobic and anaerobic in order to deal with the various matters present in the tank. * The invention of the septic tank is attributed to a French man named Jean-Louis Mouras who built the first septic tank in Vesoul in 1860. * The official use of a septic tank in France dates back to 1881. How do they work? * Once in the tank the waste starts to divide itself. * The lightest parts of the waste (fat, oil, grease) starts to float to the surface where they form a crust. This is called Suspended Solids. They will be digested by aerobic bacteria and transformed into carbon dioxide and water. (Aerobic: a life form that requires oxygen to live). * The heavier solids will drop and settle at the bottom of the tank. This is called the sludge. They will be digested by anaerobic bacteria. (Anaerobic: opposite of aerobic). * The liquid will circulate in between the two masses. * A septic tank does not really treat waste. Its main purpose is to store the waste for a period during which the waste will undergo its first transformation. This is called the pre-treatment. * It is fair to say that, at this stage, 70% or more of the pollution contained in the waste coming into the tank goes out again. * This pollution contains germs and pathogens which pose real threats of contamination and disease and is therefore very dangerous to human life. * This is why the law is now coming into force. Now, waste coming out of the septic tank into the ground must be filtered. This is called 'the treatment'. * There are many types of filtration systems available, but the choice is completely dependant on the soil composition. Diagrammatic of a Septic Tank * This type of septic tank (‘fosse toutes eaux’ in France) is the most commonly used. It receives the waste-water from the bathroom, the toilets and the kitchen. * Other systems have a separate fat trap, which only receives the wastewater from the kitchen. 
The septic tank receives all the wastewater from the house, bathroom, toilets and kitchen. The waste undergoes a digestion process. The bacteria present in the tank feed on the waste, transforming it into gas, carbon dioxide and water. This is called the pre-treatment. The second stage is to treat the waste coming out of the septic tank which contains a large number of germs and pathogens. This is achieved by using a filtration system. This system will be chosen after a soil test has been done. This is called 'the treatment'. Please note that it is a serious offence to release untreated wastewater directly into the soil or into a water stream. The risk of diseases and contamination is very high. The Control * The main purpose of the control is to ensure that all the systems which are not, or which cannot be, linked to the main sewage system are in good condition, function properly and are capable of dealing with the amount of wastewater to be treated. * So what will happen? * The body responsible for the control will contact you to set up a meeting at a time convenient to both parties. The Visit During the visit an engineer will: * Verify the access to the tank * The condition of the tank. Is it leaking? Is it cracked? * The location of the tank * The ventilation of the tank * The volume of the tank * The sludge level * The drain going to the filtration system * The nature of the soil * The proximity of water source, above and underground * The filtration system * Depending on his findings, the engineer will give you a report, which will indicate whether or not your system is working correctly. * If your system does not function correctly or if it needs some modification the engineer will explain to you how to proceed with the required changes. The Causes and Risks of a Mal-Functioning Septic Tank * Modern life does not facilitate your septic tank's life. In many cases it is too small to deal with the volume of waste water it receives. * Toilets, showers, baths, washing machines and dishwashers have considerably increased the volume of waste water. * In France a family of 3 produce on average 2.6m3 of wastewater per week. * This is compounded by the over-use of detergents, disinfectants, antiseptics and antibiotics, which slow or completely stop your septic tank. Regular Maintenance of Your System * Do not dispose of any toxic products in any of the pipes and drains linked to your septic tank. For details regarding the toxic products concerned feel free to contact us at the address below. * You must ensure that the bacterial activity of your septic tank, fat trap and filtration is replenished regularly by using a top quality product, such as a septic tank activator. For information on such products, contact us at the address below. * Every 4 months do a visual check of your system. * When the sludge content of your septic tank is more than 2/3 of the total volume, pump out a third to half of the sludge. Never empty your tank completely. * A septic tank without any sludge in it will not work and will start to smell. 20 - 30% of the sludge must remain in the tank at all times. It can take up to a year for an emptied tank to get back to normal. For New Build Houses Or Septic Tank Replacement * For a new installation or a replacement you will need to go to your Mairie and ask for an application form. (Demande d’ Installation d’un Dispositif d’Assainissement Non Collectif). * Provide all the information requested on the form. (Please contact us if you need any help with this form) * The application addresses two points: * The pre-treatment of the waste (the septic tank or MWWTP). This is the wastewater arriving from the house into the septic tank. * The treatment of the waste (the filtration). This is the wastewater coming out of the septic tank. Information Required * On the drawing, mark the area and the location of the land reserved for the waste water system (septic tank and filtration). * The topography of the land - is the land flat or on a slope? * The nature of the soil between 50 and 100cm deep. Does the ground absorb water slowly, quickly, or not at all? * Is the land at risk from flooding? * Is there any drinkable water source on the land be it Public or Private? * Number of people living in the house. * Does your commune have an existing wastewater system or methods in place? * The type of system you would like to use and its size. * A soil test to ensure that the filtration system chosen is compatible with the type of soil on your property. The Size of Your Septic Tank
Waste-water System Layout 
Key to above:
Information * If you are planning to upgrade your existing system or install a new one. * You should consider using a mini WWTP. * There are many benefits in using a mini WWTP instead of a conventional septic tank. Author: Jean-Claude Bardot
To receive further technical data or general information absolutely free contact BIO-SOLV E-mail: info@bio-solv.net Web site: www.bio-solv.net Disclaimer: This article should be regarded as a guideline only. It has not been updated since Sep. 5 2005. Total France cannot warranty that the information it contains is either accurate or current. Do not make any decisions without obtaining professional advice that you know to be current. The above article is © the author where stated, or © TotalFrance where no author is named The article may be printed for personal reference, but may not be published,copied or re-used for any other purpose without permission. |
