Simultaneous multi-site railway embankment steep slopes (batters) erosion control for a new spur line

The Bauhinia Regional Rail Project (BRRP) is the construction of a 110 km spur line linking the Rolleston Coal Mine to the Blackwater rail network in Central Queensland, Australia. It will generate rail traffic of 8Mt/year of coal from Rolleston mine by 2008. BRRP is currently under construction and is expected to be completed by the end of 2005. The new spur line includes several embankments that need to be protected against erosion. Erosion of unprotected railway embankments causes serious maintenance and environmental problems within the project region. Earlier research has demonstrated that revegetation of the batters minimises the erosion risks considerably. Therefore the cost-effective erosion control strategies of the ongoing HEFRAIL Research Project are integrated with the earthworks construction. In order to reduce the treatment costs, the embankment batters are categorised with different levels of treatment. The top 3 m of batters of all embankment sections exceeding 4 m in height and embankment batters on the downstream side of the two major flood plains are receiving the full HEFRAIL erosion control treatment. The full HEFRAIL treatment involves topsoiling, grass seeding and drip irrigation system set up to aid in the grass establishment. The remaining embankment batters are receiving the full treatment except for the drip irrigation. Water from existing dams and creek water holes, from earthworks construction water tanks, and from road delivery to temporary tanks located within the rail corridor is being used to supply the irrigation water. The slow germination process and low germination rate of the preferred drought resistance buffel grass impose a serious bottleneck for the rapid grass establishment required for erosion control. Therefore an attempt has been made to increase the germination rate and accelerate the germination process by soaking seeds for 5 mins in water and pre-germinating in potting mix before spreading on the batter surface. Sulphuric acid treatment in the laboratory produced excellent results but has limitations for mass treatment, and it is being further investigated for improvement. Good emergence of buffel and Rhodes grass on the railway batters within a week of seeding with pregerminated seeds has been observed where the irrigation water is secured. In general very good grass coverage is being achieved within 8 weeks after seeding with irrigation.