Septic Tanks and Wastewater
Regulations applying to individual wastewater systems: primarily septic tanks (fosses septiques) Mini Wastewater Treatment Plant (WWTP) and fat traps...A septic tank is a large tank where all the waste-water from a home is stored and receives basic treatment. SPANC (Service Public d’Assainissement) are responsible for regulating and inspecting septic tanks. They can also offer advise and assistance insuring septic tanks meet the current regulations. 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.
- Once in the tank, the waste starts to divide itself
- The lightest waste (fat, oil, grease) floats to the surface where it forms a crust. This is called suspended solids. Suspended solids are 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. Sludge is digested by anaerobic bacteria. (Anaerobic: opposite of aerobic)
- The liquid circulates between the two masses
1 January 2006As a result of a regulation of 1 January 2006 only registered pumping companies (vidange) may remove untreated waste from a septic tank. The use of an unauthorised company could lead to fines for both you and the pumping company. Furthermore, septic tank owners must have a certificate or record of all pump-outs and maintenance carried out on your septic tank system. A certificate can only be issued by an authorised company. You will be required to show proof of maintenance when your tank is inspected. If you do not have any record of your septic tank having been emptied you will be ask to do so using an approved company. Under the new regulation, a septic tank should be pumped once every four years on average.
The ControlThe 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. (The body responsible for the control will contact you to set up a meeting.) During the visit an engineer will check the following:
- 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.
New and Replacement InstallationApplication for a new installation or a replacement should be made at the mairie. The application is a Demande d’ Installation d’un Dispositif d’Assainissement Non Collectif. 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 requiredOn the drawing, mark the area and the location of the land reserved for the waste water system (septic tank and filtration).
- Note the topography of the land (flat or on a slope)
- Explain the nature of the soil - its absorbency and how quickly water drains (if at all) - from a depth of 50 and 100cm
- Note if the land at risk from flooding
- Note if there is a source for drinkable water on the land, either public or private
- Note the number of people living in the house
- Note if the commune has existing wastewater system or methods in place
- Note the type of system you would like to use and its size
- Include a soil test to ensure that the filtration system chosen is compatible with the type of soil on the property
Size of a septic tankWhen choosing a septic tank the following parameters should be taken into account.
- Water consumption in France is on average 175 litres per person per day
- Add to that 50% in order to take into account the space occupied by the waste already present in the septic tank
- The water height in the septic tank must be 1 metre
- The width must be 1.20 metres
- The length of the septic tank is equal to: capacity in M3/Water Height x Width
- The retention period must be of 2 to 3 days
|Occupants||Water consumption - litres per person Per day||Waste volume per day = Nb occupents x 175Lt + 50%||Waste volume to be treated per day in M3||Waste retention in days||Septic tank minimum capacity in M3||Septic tank recommended capacity in M3|
- Reduce the number of pumps out required
- Reduce the impact of accidental release of toxic products in the septic tank
- Provide a longer retention time which will reduce the risk of blockages in the drain from tank to soak away
Waste-water System Layout
Key to above:
- Fat trap (optional) unless a tank is more than 10m from the house
- Septic tank
- Rainwater (must never come in contact with your wastewater system)
- Drains ventilation
- Septic tank ventilation
- 7m distance between house and septic tank. If the distance between the house and the septic tank is over 10m a fat trap must be installed
- 35m minimum distance between filter and water source
- Neighbouring fence minimum 3m
- Large trees and shrubs must be at least 3m from the tank to ensure that the root systems do not damage it or the filter
- Access and observation points for fat trap, septic tank and filter
Information supplied by Jean-Claude Bardot of Bio-Solv Tel: +33 (0)5 53 93 56 64, Mobile: +33 (0)6 33 82 77 41, email / www.bio-solv.net Copyright © Jean-Claude Bardot All Rights Reserved