Dan Millgate

[Bostonshire]

No Drainage under the pitch yet just capped pipe work (so still sealed) Ground would need to settle first or the land just runs into the system resulting in a complete Blockage. I to had this concern so did a bit of looking it up

[Ed Kandii]

No Drainage under the pitch yet just capped pipe work (so still sealed) Ground would need to settle first or the land just runs into the system resulting in a complete Blockage. I to had this concern so did a bit of looking it up

There should be catch-pits before the pitch drainage joins the main storm water system to avoid this blockage happening.   
There's also likely to be a drainage layer below the topsoil, with a geotextile membrane to prevent the fines washing through into the pipework.  8)