In December, a Tweed Shire Council infrastructure project was recognised in the New South Wales Local Government Excellence in the Environment Awards.
Council received a commendation in the ‘Natural Environment Protection and Enhancement: On ground Works’ category for its O’Brien’s Bridge replacement project, which incorporated restoration of threatened species habitat.
The project combined the skills of engineers, ecologists and bridge construction personnel and resulted in positive outcomes for biodiversity, while delivering on infrastructure.
O’Brien’s Bridge is located at Mt Burrell on the southwestern outskirts of the Tweed.
As an important link to Kyogle and Lismore Shires, the dilapidated timber bridge was replaced with a concrete structure funded through the RTA’s Timber Bridge Replacement Program. However, the project was more than just an engineering exercise.
Impact assessment studies undertaken by Council during the preapproval planning phase for the bridge replacement identified environmental concerns in regards to flora and fauna.
The studies found one NSW threatened bat species – the large footed Myotis – roosting within the bridge structure; a threatened frog species – the Giant Barred Frog – within the waterway; and an endangered ecological community (lowland rainforest EEC) bordering the site.
The site is one of only two known Myotis breeding sites within the Tweed Local Government area and one of only a few known locations within the Tweed where the Giant Barred Frog is known to regularly occur.
To overcome impacts to biodiversity, the design of the proposal was significantly modified and mitigation measures implemented to limit impacts during demolition, construction and operational phases of the project.
Council’s Environmental Scientist David Hannah said incorporating artificial bat roosting habitat under the new bridge had proved to be a success.
“The incorporation of selected mitigation measures has meant that the works have not displaced the populations of threatened species that previously occurred at the site as evidenced by the presence of both species at the site since its completion,” David Hannah said.
“Monitoring of Myotis beneath the bridge since its completion in January 2010 has recorded the species regularly using both the bat boxes provided, and the gaps between the bridge decks.
“In addition, targeted call playback at the site recorded the Giant Barred Frog as being present downstream of the bridge.”
While the development resulted in an initial loss of approximately 474 square metres of regrowth rainforest, and 290 square metres of Eucalypt Forest from the site, Council is undertaking revegetation works to replant 2,700 square metres of riparian vegetation. This is approximately 3.5 times greater than the initial area.
For further information contact David Hannah, telephone
(02) 6670 2400.
