This is a perfect example of what SWM can do when involved in the design phase.
Drainage of the oval was originally designed by others using obsolete sports turf drainage practice – slotted PVC pipe, 50mm rubble aggregate and geofabric wrap. The intention of this design was for 33% of the oval to be drained, but in reality, this would probably end up as low as 3-5%. We at Subsurface Water Management have seen this happen many times with the same outcome.
SWM offered an alternative design with subsoil drains installed parallel to the irrigation laterals, therefore reducing the number of intersections. These drains were specified in line with current industry best practice – 100mm slotted Draincoil laid in a single pass operation in a bed of 5mm washed blue metal aggregate to precise laser grade. We were careful to avoid geofabrics due to the presence of high concentrations of iron bacteria endemic in the local soil. This iron bacteria will invariably culture in the geofabric, preventing free water ingress; in other words, short lived, ineffective drains.
The 33% that Subsurface Water Management drained was so successful and cost effective (dollars per square metre drained) that we were asked to provide subsurface drainage for the rest of the oval.