Case Study - “the Waterways” Mordialloc Creek
"The Waterways" Mordialloc Creek - building in progress
Background
The construction of wetlands along Mordialloc Creek west of Springvale Rd had been proposed for many years. The Mordialloc Creek And Environs Opportunities Plan (1991) recommended these measures to assist with the treatment of catchment runoff from the local catchments, as well as treating flows from the Dandenong Creek diversion at Pillars Crossing.
The developer "The Portland House Group" has paid for the development and reconstruction of Mordialloc Creek floodplain and wetlands.
Aim
The wetlands will reduce pollutant loads to Mordialloc Creek estuary and Port Phillip Bay. State of the art principles in wetland design have been applied for online, floodplain type systems.
The wetlands work as part of a treatment train with primary treatment of sediment and litter being conducted at, or near, source through the catchment. These measures are also in place at the Cheltenham Rd Retarding Basin and Keysborough Retarding Basin upstream of the site.
"The Waterways" Mordialloc Creek - a few years after construction
Technical Information
| Wetland Type : | Online side cast floodplain wetlands. |
|---|---|
| Site Size : | 5.0 ha in creek cells and 46 ha in offline wetlands plus a 13ha open waterbody. |
| Maximum Inflow : | base flow of about 10 MUd and fully on line in an event up to the 1 in 1 yr ARI, and will provide partial treatment to about 70% of Mean Annual Rainfall to local catchments. |
| Assumed tc : | Not a factor as principally engaged once flows rise above base Bows. |
| Primary Treatments : | Sediment distributed across the catchment and in the waterways upstream of the site. Some wetland treatment upstream of the site at Cheltenham RD and Keysborough RB's, and potentially the floodplain system to be developed in conjunction with a new residential development upstream. |
| Floodplain Storage Offset : | Substantial excavation of the floodplain has occurred and fill has been exported off the site to offset the floodplain storage. |
| Wetland Planting Arrangement : | The floodplain sidecast system is a series of ephemeral marshes with a combination of macrophytes and swamp scrub, fed by side cast from the creek, above base flow. The sedimentation pools have fringing macrophytes. |