A lot of the recent Hobart flooding related to blocked and failed drainage infrastructure.  On Mt Nelson most grated roadway drains blocked with twigs, bark and leaves causing overland flow into houses, basements and buildings below hard paved surfaces.  Almost all street drains on Mt Nelson ‘The Bends’ lack the slotted culvert which lies behind typical guttered gratings.  This allows flood flows of water to drain into the STORM WATER drains.   So the storm water system became very ineffective causing water to flow off the roads and into basements and lower floor levels.  Thus flooding of houses occurred on a mountain well away from drainage lines or floodplains.  Mt Nelson Rd (‘the Bends’ section) urgently needs grating with slotted type culverts fitted to prevent future overland flows into houses….see photos below.

Below — Grating but no curb nor slotted culvert behind grating which is required….see below (note leaves, barks and twigs, these have even accumulated after the post-flood clean-up, so you get the idea they block up quite easily).

 

Below – whats needed! – grating + slot drain/culvert as shown below!   So more of these grating + slot culverts are needed to stop our houses flooding in future on Mt Nelson…..yes please!!

Above – an example of the importance of slotted culverts in addition to gratings —  note this grating, at Kingston, is totally blocked with leaves, twigs and silt – BUT the slotted culvert is still able to remove flood waters.  There is a desperate need for such infrastructure on Mt Nelson bends to prevent future flooding.

Above – water ran down the road due to blocked gratings and headed down the Mt Nelson steps carrying some of the the grating-blocking debris (bark, twigs, leaves) as shown.

Above – examples of blocked drains (during May floods) – twigs, bark and leaves can very easily block under-sized infrastructure.

 

Above – Blocked open drain – once again over-run with leaves and twigs – this hinders the water entry from other drain-pipes.