Mis-used soakaway - Question on likely damage

[BillyBigBrains]

I own a Victorian cottage in Derbyshire. Recently I discovered that our washing machine and dishwasher have been discharging into a rainwater soakaway, instead of into the mains drainage system (we have two adjacent drainage grids and the discharge pipe wwas routed into the wrong one - and has been since before we bought the house). The system has run like this for at least 20 years! However, the recent outflow of soapy water on the surface of the garden led to my discovery. I have fixed the immediate problem by re-routing the machines' discharge to the main sewer grid. But should I be worried about the sheer quantity of water that has been hitting the soakaway? The washing machine has been used several times daily and must have pumped thousands of gallons into the ground. Is it likely to have caused any serious damage? The property is built on Keuper Marl.
Thanks in advance.

[flowjoe]

The grease, fat and fibres entering the line may well have partially sealed the sub-soil around the soak-away which could consist of either a large pit full of rubble or a loose brick covering the end of the outlet pipe.

If the line continues to overflow during heavy rainfall locate/trace the outlet to the soak-away and extend.

[BillyBigBrains]

Thanks for the advice. I've dug out the existing soakaway around the outlet pipe and you're right - it's a deep hole filled with brick rubble and lined with a dark greasy residue. I'll extend the pipe to a cleaner area and build a new soakaway there.
Many thanks!
Bill