- Thursday 18 November 2010
A new bridge built over Six Mile Creek at Grahams Road, Pomona, will improve floodwater management in the area.
While the bridge will be only a few centimetres higher than its old timber counterpart, the smoother lines and design will better manage the creek’s fast flows, at the same time ensuring less upstream build-up.
Division 12 Councillor Lew Brennan said Sunshine Coast Council engineers had fully considered appropriate height levels for the new bridge to ensure any solution did not create further problems elsewhere.
Last Tuesday, Cr Brennan attended a meeting on-site to hear and respond to concerns of the 30 residents who are affected by flooding, accompanied by both council and independent engineers.
"Council would like to assure residents that the flooding of Six Mile Creek was fully considered during the planning and design phase of the new bridge, and that the bridge was analysed at its current level and a level 500mm higher," he said.
"While hydraulic calculations at the time showed very little benefit in raising the bridge and some risk to upstream flood levels, council has decided to raise the new bridge by 150mm to take into account some residents' concerns."
Cr Brennan said the new bridge would allow an extra 30% of water to convey in a flood situation without adversely affecting upstream water levels.
"The removal of bridge piers in the creek along with the old bridge and a smoother underside finish on the new bridge will allow this improved flow of water to happen," he said.
"Improving the water conveyance under a bridge is an alternative to raising a bridge when the approach roads are low; raising the bridge would simply divert the water around it.
"It is also a better solution when the surrounding land is low, and upstream water levels from built-up road approaches and bridges increase upstream flooding risk."
Cr Brennan said neither bridge would function as designed while they simultaneously straddled the creek and the proof of the new bridge's abilities would appear after the old bridge was removed.
He also said based on advice from residents council would investigate the removal of a "log-jam" immediately downstream from the bridge.
"But this work can not proceed until council has fully investigated the possible impact on fauna that may be using the site," Cr Brennan said.
In additional benefits for Grahams Road residents, a bitumen off-ramp to the gravel road from Louis Bazzo Drive will be installed for added safety, along with a convex mirror at a tight bend to aid driver vision.
The completion of the new bridge, removal of the old one and associated road re-alignment is expected by early December, weather permitting.