Some photos of the drain investigation and clearance by Mitchell & Mayle and members of AS' Resources Action Group during January 2020.
One instance is shown of the long, matted material pulled from the underground pipes.
Subsequent work by M&M on January 29 repaired the broken water drain pipe (breakage clearly caused by relatively recent ram-through of yellow gas main), set a safe riser above the soakaway, capped with a screwed-down lid, and integrated the hose from the sump-pump in the basement. The pump is now continually switched on and will operate as required under the control of the float-switch in the sump.
Finally, a dry area in the basement for the boilers!