I need to replace an old blocked soakaway from my cesspit any advice?

I've got a cesspit which is probably about 50 years old but over the last 6 months or so the soakaway has stopped working, so i need to replace it with a new one, various people have suggested using perforated pipe / slotted pipe which is finebut how long do i need to make the run of pipe and what do i need to pack around the pipe to create the soakaway? and how much of a fall do i need to put on the pipe? I do get the cewsspit emptied regularly so this is only for the waste water and the land I've got drains really well, any advice would be great, cheers.I need to replace an old blocked soakaway from my cesspit any advice?
a cess pit is just that ..a pit ..its purpose was to collect all the foul waste ..not any rainwater ..and it was stored there until it was empied ..there never was any pipes leading away from a cesspit as it was raw sewage and would have contaminated the land ..the other type was a ceptic tank ..this consisted of at least two chambers ..interconnected ..and then you did have pipes leading away from them to a soakaway ..the ceptic tank worked on bacteria breaking down the solids ..these tanks should never be empied ..should never need to be if constructed right ...the sewage comes into the first tank and is deposited into the tank below the surface..so as not to break the bacterial crust that has formed on the surface it is very inportant you do not harm this crust as the surface is sealed and the bacteria can do its job ..thats a good reason alone that you never empty it ..then the waste passes into the second chamber..and same again ..crust etc ..by this stage the liquid is reasonably clean ..it then leaves the second chamber..againbelow the crust so as not to disturb the surface ..it passesaway from the tanks .in the old days the pipes laid herringbone fashion ..that is a long pipe with pipes coming out each side a bit like a fishes backbone ..they were beddedin gravel all round to aid drainage some up to 50 yards long ..as time went by these pipes and gravel became clogged ..and need renewing ..modern plastic pipes have holes all round ..they still need gravel surround..at least 300mm..and a membrane to keep it clean but now you can run it round in a circleI need to replace an old blocked soakaway from my cesspit any advice?
I've recently had mine done at a cost of 拢4000.





The soakaway has a run of 30 metres of slotted pipe in three 10 metre runs all connected together. Slotted pipe is less prone to blockages.The pipe is at a depth of approx 1 metre and is bedded onto 25mm to 50mm gravel, it is then surrounded by gravel to a depth of about 300mm and covered by a waterproof membrane (stops the soil filtering into the soakaway)





The outlet from the septic tank goes into a chamber into which there is fitted a submersible pump on a float switch, the pump pumps the liquid from the chamber into the soakaway.





The reason for the pump is simply to reduce the depth at which the soakaway can be constructed as the outlet from the septic tank is quite deep.