Land Drains for Septic tank

[roboughton]

I have a septic tank old brick style out in out paddock. 4 bed house in the sticks.

I want to re do the land drains as i am sure this is not adequate or is choked up, i am after advice on doing this myself as i can get hold of the tools no problem and cost is an issue. I also like to know how things work

My first Q's are

What size pipe should be used?

How long should the drain/soak field be?

What stone should i put in the soak field? i can get gravel from the local quarry quite easy but its a lime stone and i was told you should not use this.

How deep should i go with the drains and i read somewhere it should go up hill but that does not make sense to me.

 

[noseall]

the run-off from a septic tank is usually arranged herringbone pattern and laid with 110mm pipe.
try the klargester site.

 

[roboughton]

Thanks i am going to do it myself i think some more research for me i think

 

[wastetech]

How to Construct Soakaways and Drainfields

Use SOLID perforated 110mm. foul drainage pipe, with the slots/holes at the bottom, laid in trenches of a uniform gradient not steeper than 1:200. Perforated 'Flexicoil' type pipe is NOT allowed.
Pipes should be laid at a minimum depth of 500mm and a maximum depth of 700mm. to enable aerobic contact between the effluent and the soil particles.
Pipes should be laid on 300mm of clean shingle, gravel or broken grade 1 stone ( 20mm – 50mm ).
Soakaway trenches should be filled with stone to a level of 50mm above the pipe and covered with a layer of geotextile membrane to prevent silt entry.
The remainder of the soakaway trench can be filled with topsoil.
Drainage trenches should be between 300mm and 900mm wide with areas of undisturbed ground of 2m wide between parallel trenches.
An inspection chamber should be installed between the septic tank and the drainfield.
The soakaway layout should be set out as a series of parallel pipes connected by an outer drain - much like the design of an oven shelf.
fed from the inspection chamber, NOT a straight pipe run with an 'end'. The herringbone system has been superceeded in the BS 6297 2007.
The maximum pipe run for each line is 30M.
The area of the soakaway is calculated after carrying out a minimum of three percolation tests in the proposed drainfield area, over three consectutive days and applying a formula as detailed in Section H of the Building Regs.

Soakaways for septic tanks and sewage treatment plants are required to be a minimum of :-

10m from a watercourse or ditch.
50m from water abstraction points.
15m from any building, and sufficiently distant from any other soakaway, including roof water.
The soakaway or drainfield area should be downslope of groundwater sources.
No water supply pipes or underground services should be within the soakaway area.
No access roads, driveways or paved areas should be within the soakaway area. This includes fields with tractor and agricultural vehiclular traffic.
The water table or bedrock must not, at any time, be within 1 metre of the bottom of the soakaway trench.