How Much Is A Septic Tank - Septic Tank Sewage Treatment Systems - These find the money for a utterly clumsy method of treating sewage for properties which are not similar to mains drainage. Many septic tank systems throughout the world are never maintained and thus realize not feat properly and pollution control laws exist to attempt to limit the amount of environmental and health risks they cause. These laws are getting tighter, and minimum standards have been put in area for new or replacement septic systems. In many cases you will habit to install a sewage treatment forest system instead. Always get the sewage system checked by a waste water system adroit prior to purchasing a property in order to prevent a pollution problem.
Types of Septic Tank Systems Available
There are various types of septic tank systems. They consist of an underground septic tank in differing shapes and sizes, which next connects to a supplementary soil treatment system, usually a house drainage system in the form of a soakaway or drainfield, or a mound soakaway.
How a Septic Tank works
Raw sewage and waste water from baths, kitchens, etc. discharges into the tank, where the solids are separated from the liquid waste. Fats and oils float to the top of the tank and form a crust layer. Faeces and food scraps sink to the bottom of the tank and form a sludge layer. Anerobic bacteria which are natural colonisers in the tank "digest" this sludge by up to 70%.
The filthy septic water flows out of the tank to a soakaway or drainfield. Baffles or 'T' pipes in the tank preserve assist the aimless crust and prevent it from entering the outlet of the tank. In order that the sludge and crust layers realize not become too deep, septic tanks should be emptied annually. This then prevents a well along and well along inclusion of suspended solids washing out into the soakaway. Solids can block the let breathe spaces in the soil drainage system, creating a drainage hardship and the septic tank effluent will not be dexterous to soak away or be treated by the natural soil bacteria.
Variations in Septic Tank systems
Traditional septic tanks comprise of two rectangular chambers: the first one visceral 2/3 of the combination and the second 1/3, usually built in brick or concrete. Strict design rules are in area and septic tanks must be intended in accordance bearing in mind BS 6297 1983. The inlet pipe into the first chamber ends in a 'T' pipe which travels beside the at least 450mm (18") under top water level (TWL), and the chamber must be a minimum of 1500mm (5'-0") deep from TWL. This first stage chamber is usually twice as long as it is wide. The pipe from the first chamber into the second chamber consists of an 'H' pipe and the bottom of the pipe is a min. of 300mm (12") under TWL in the first chamber and 450mm (18") under top water level (TWL) bearing in mind it enters the second chamber.This second stage chamber is usually square. The outlet pipe from the second chamber of the tank then consists of a 'T' pipe bearing in mind the bottom of the pipe 300mm (12") under TWL.
Vent pipes should be installed from the first and second chambers for venting the gases, mainly methane and hydrogen sulphide, that are produced by the sludge. strong covers should always be placed utterly over a septic tank to avoid kids / animals falling into the tank. There are many cases of thcovers collapsing and many people have been killed as a result.
Nowadays, septic tanks are made in GRP and polyethylene which commonly are spherical in touch bearing in mind a narrow shaft at the top to a manhole sports ground level. These realize not develop the same environment of effluent as two chamber tanks and cannot be placed in front of many conversion units.
Care should be taken to ensure that problems will not occur due to the tank rising out of the ground, bearing in mind it is emptied in tall water table sites. It is always advisable to install the tank bearing in mind a tangible surround.
Septic tank effluent nevertheless contains more or less 70% of the pollutants in the indigenous sewage and needs new treatment in the soakaway to prevent a pollution problem.
Soakaways and Septic Drainfields
The Septic Tank without help provides the first allowance of the sewage treatment process. The soakaway is the underground soil treatment system which uses aerobic bacteria found naturally in the sports ground to new treat the effluent. The soil type must be tolerable for a soakaway to feat properly. Percolation tests are required to determine whether a septic tank soakaway is suitable. If the soil is clay, it is not tolerable for a soakaway and a drainage hardship is inevitable. If you have this hardship next a sewage treatment forest is the reply as they realize not habit a soakaway.
The soakaway consists of either a series of trenches containing perforated pipe laid upon and surrounded by stone, or an absorption bed, or a soakaway mound, every of which are similar to the septic tank outlet by a pipe. In every cases the soakaway must be a minimum of 1.2 metres above the water table or bedrock at every times. They must then be a minimum of 200 mm. under sports ground level to avoid septic effluent breaking to the surface. The pipes should be laid at a gradient of no more than 1:200 in a drainfield in order that the wastewater does not control to the stop of the pipe, but is dispersed evenly. The perforations should be larger than 6mm (0.25") to avoid the biomatt, which forms in the trench, blocking the holes. The pipe cannot be the corrugated tubing type as used in house drains as this is not allowed, but must be the truthful unquestionable soakaway drainage pipe
The contaminants, pathogens, nutrients, and organic thing in the effluent are dispersed into the gravel where they are digested by aerobic bacteria.
On a oblique site, the effluent may flow into a series of fall boxes or manholes bearing in mind different outlet to the bordering pipeline set at a demean level. Absorption beds are useful where proclaim is limited, but they should without help be used as a second choice.
Sewage Drainage Mounds
A treatment mound is a raised soakaway system. Aggregates are used to lift the soakaway thus that it is at least 1200mm (4'-0") above the seasonal tall water table or bedrock. The mound system must be intended carefully, taking into account the topography of the site, the volume of septic tank effluent to be treated and the porosity of the topsoil to avoid failure of the system and boggy areas in relation to the base of the mound. The design cannot be guessed and must be ended by a trained professional, using exam results and calculations.
I have seen awfully intended mounds blast a hole through the side as they have been too small for the job.
Effluent is piped to a pumping station tank, where it is pumped in batches into the mound pipe-work. Septic mounds can see utterly handsome and can form allowance of the landscaping of a garden. You are not allowed to forest shrubs upon top of them, but they can be planted in relation to their base.
Septic Tank Soakaway Pits
In the past, many septic tank systems used soakaway pits, although these pits are no longer ample under protester building regulations. They consisted of a large hole in the ground, log on at the bottom, either blocked circular bearing in mind gaps with the blocks to allow seepage of the effluent into the soil, or conveniently holes filled bearing in mind stones. Some soakaway pits were made of large tangible rings bearing in mind gaps with the rings and the septic tank effluent was piped into them. They were always covered, usually bearing in mind a large tangible slab, but they were often a failure, as no calculations were undertaken to determine the porosity of the surrounding soil and they soon were filled bearing in mind septic effluent. The drains next occupy with the pit and the tank, which backs-up the entire septic system.
Site Conditions and Installation
Most sites in the UK are not tolerable for septic tank systems. Either the soil contains too much clay or is too porous, or the winter water table or bedrock is too close the surface. If the soil is clay, next it will not soak the septic effluent away and if it is too improper it will not preserve the effluent long ample for treatment. You could deem a non-electric sewage treatment forest instead. Sometimes, it is realizable to accustom yourself a septic system to raid a basically improper site, but this requires cautious planning and design by an expert. As a general rule, if the site has either insufficient soil depth, or the incorrect type of soil, it is not tolerable for a septic system. Always log on your Building Inspector before deciding upon a septic system.
The size of a septic system, both the tank and the soakaway area, is distinct by the number of bedrooms in the home and porosity of the soakaway soil. A septic system cannot feat if it is overloaded, thus always bear in mind any plans you may have for extending the property before you deem upon the size of the septic system. Increasing the size well along results in a ruined garden.
Finally, always check bearing in mind the environment Agency and you local Building control before deciding upon a septic system. They will have a utterly fine idea as to whether it is likely to feat in your area and could save you thousands of pounds in replacing an improper septic installation.