Key points
- Flood-compatible construction materials should be used below 1% annual exceedance probability flood levels.
- Small design changes can significantly increase resilience.
In March 2012, North Wagga Wagga in the Wagga Wagga local government area suffered severe flooding following significant rainfall, which resulted in substantial property damage and loss.
The Palm and Pawn Hotel was established in 1876 in North Wagga Wagga. It is on the northern side of the floodplain of the Murrumbidgee River. The hotel, now known as the Palm and Pawn Motor Inn and Tavern, underwent an array of development and redevelopment changes since its establishment. Of these, many have been associated with storm damage (most notably in 1938) and flood inundation (in 1952). The ground floor area was concreted in 1954 to improve flood resilience.
The risk from flooding is significant. The ground floor level of the development is approximately 1 m below the 2011 1% annual exceedance probability flood level in North Wagga Wagga.
The most recent significant flood was in 2012, when the Murrumbidgee River peaked at a height of 10.56 m, the largest recorded height since 1974. The worst flooding occurred in the North Wagga Wagga area, where water topped the levee banks. The ground floor of the Palm and Pawn was inundated by floodwaters and required an extensive clean up.
In 2020, the motor inn submitted a development application for alterations and additions to portions of the ground floor and outdoor areas, which the council approved. While natural hazard mitigation was not the driver of the proposed development application, it was a key consideration. There was a strong recognition that the works should meet and exceed Wagga Wagga City Council’s flood-related planning and development controls. The proposed initiatives included:
- using flood-compatible materials for alterations and additions below the 1% annual exceedance probability flood level
- raising power outlets approximately 1 m above the floor level and adding residual current devices to avoid damage in a flood event.
The development increased the gross floor area of the Palm and Pawn from 499 to 577 m2.
The extension largely incorporated flood resilience materials, and minor upgrades were also done to the existing building.
Palm and Pawn flood resilience elements
| Category | Flood resilience details |
|---|---|
| Foundation/floor | Concrete strip pad footings and reinforced concrete slab |
| External walls | Core-filled and reinforced brickwork |
| Openings | The use of vents is appropriate to allow floodwater to enter, preventing a pressure differential and buoyancy |
| Wall insulation and linings | Galvanised steel frame with polystyrene insulation, tiled-over fibre cement sheeting |
| Electrical | Switchboard and most connections set above the 1% annual exceedance probability flood level |
| Sewer | Installed with backflow devices |
| Goods and equipment | Standalone equipment raised 75 mm above floor level – equipment will be relocated in the event of a flood |
| Floor coverings | Broadloom carpet (sacrificial element to allow cleaning of concrete base), along with epoxy floor and ceramic tiles |
| Fencing | Post and rail timber, playground has brick fencing with one open wall for floodwater access |
| Framing materials/doors | Aluminium door frames |