Changes

==Maintenance and inspection==

==Maintenance and inspection==

*Well(s), of 100 - 150 mm diameter perforated pipe, should extend to the bottom of the facility.

*[[Wells]], of 100 - 150 mm diameter perforated pipe, should extend to the bottom of the facility.  

*Where a horizontal underdrain is being installed, an upstream and a downstream well should be coupled to the underdrain pipe. The pair of wells can then be used to flush out the length of underdrain if required.  

*The exposed tops of all wells should be fitted with lockable caps.

*The exposed tops of all wells should be fitted with lockable caps.  

==Material specifications==

==Material specifications==