155km Pacific Hwy upgrade immune from 1-in-20-year floods
AN UPGRADED Pacific Hwy would have remained open during January's record flood, according to the latest Roads and Maritime Services report on the project.
The Woolgoolga to Ballina Pacific Highway Upgrade Submissions/Preferred Infrastructure Report says an assessment of the January 2013 flood in the Clarence Valley had 'verified' the river flood model used in the environmental impact statement.
The report quotes the EIS which claims the new highway, "would not be cut in any location for any period of time for this flood".
The project covers the upgrade of about 155km of highway from Woolgoolga to Ballina.
It projects a completion date about 2020 if federal and state governments can agree on funding.
The project design gives the highway immunity from a 1-in-20-year flood on the Clarence and Richmond River floodplains, with the 20-year event measured to the edge line of the road pavement.
"The highway would still be trafficable during these flood events, with no inundation of the travel lanes," the report said.
The report also contains a supplementary hydrology assessment, to address issues raised by the community and the January flood in the region, with emphasis on the Corindi River floodplain (particularly Blackadder Creek) and the Shark Creek and James Creek areas.
The results of the additional modelling and impact assessment would be overseen by an independent reviewer and used to inform detailed project design, according to the report.
All impacts 'would need to be further considered at the detailed design phase'.
The assessment also used January flood data to confirm the suitability of debris blockage strategies
While the Clarence Valley Council submission on the EIS supported the upgrading of the highway, it raised issues of local and regional access, biodiversity and hydrology and flooding.
- The 'refined purple route' between Glenugie and Harwood is estimated to cost more than $1.03 billion.
- Construction of the Glenugie-Ballina Hwy will generate 1.4 billion cubic metres of surplus material that will need permanent stockpiling or use. There should be no need to dispose of surplus material off site.
- By 2026, there could be a reduction of 15,000 tonnes of carbon dioxide a year compared with emissions from the existing highway.
- By 2036, around 14,000 vehicles a day are expected to use the highway.
- A more precise assessment found that the project would lead to the loss of 375ha of koala habitat, rather than the 557ha reported in the EIS.
- The Glenugie-Tyndale section had the highest number of crashes from 2005-2009, with 182.