UPGRADING ST HELENS BEACH BOAT RAMP WITH SS GEOGRID AND MIRAFI PET

Pensar Civil were awarded the $1.7 million contract to upgrade the existing boat ramp facilities at St Helens Beach in North Queensland as a part of the Queensland Government’s Marine Infrastructure Fund.

Work included raising the height and increasing the slope of the existing boat ramp and access causeway, as well as construction of a rock groyne/ breakwater to protect the ramp from wind and wave action.

The new ramp needed to meet the requirements of Main Roads Standard Drawing 4021, which specifies Geogrid SS30 and Geotextile P39. PET 800/50 high strength woven geotextile was specified as basal reinforcement for the project specific breakwater.

For construction of the ramp Texcel P39 non-woven staple fiber geotextile was placed as the separation layer on existing material followed by SS30 geogrid in maximum 1 m lifts of compacted 75 mm rock. The ramp was finished with precast concrete panels.

Tensar were on site for approximately 12 weeks to complete the project which was scheduled around tidal windows. Tides during the construction period varied between 0.4 m at low tide to 6.26 m at high tide. At high tide the entire project site was inundated requiring all people, plant and equipment be relocated to higher ground.

Adding to the site challenges this area of the North Queensland coastline is subject to crocodile sightings so staff had to ensure a spotter was always available.

PRODUCT USED

Tensar® SS Geogrids

• Two primary directions of strength and stiffness
• Efficiently interlocks with granular materials
• Reduces aggregate layer thickness
• Increases pavement life
• Controls differential settlement
• Proven technology

Solmax Mirafi® PET High Strength Woven Geotextile

• High long term design strength with low creep effects
• Enables optimum embankment height over a minimum area and steeper side slopes
• Increase in construction speed with no loss of stability
• High Strength - with grades from 100kN/m to 2,000kN/m
• Custom roll lengths can be manufactured to facilitate ease of installation and reduce wastage on site
• Long term properties for proven performance over the lifetime of the structure as its used in the most complex infrastructure projects in the world
• Complies with all ANZ road authority requirements including certificate of conformance requirements
• Design support available