Stream-adjacent retaining walls are a specialist category of their own. They need to satisfy structural engineering requirements for the embankment above while also meeting the environmental compliance requirements for work near waterways - and ideally, they need to integrate visually with the riparian environment rather than presenting a stark concrete or timber face to the stream.
This Kaiapoi project used a combination system: driven timber poles as the structural foundation along the stream edge, with a vegetated FlexMSe (Mechanically Stabilised Earth) wall system above. The FlexMSe facing allows planting to establish through the wall face, so over time the structure becomes part of the natural streambank rather than an obvious engineered structure.
What is a FlexMSe Wall?
FlexMSe is a geosynthetic reinforced earth system that uses layers of compacted fill reinforced with geotextile strapping, with a flexible mesh face that can be planted. It's particularly suited to sites where a traditional hard-face wall (concrete block, timber pole) would look out of place, or where the engineering loads require a deeper structural solution than a surface wall can provide.
TBT Earthworks is experienced with multiple retaining wall systems across Canterbury - timber pole, concrete block, crib, rock, FlexMSe, and gabion. If you're not sure which system suits your site, call Trent on 027 858 0556 for a site visit and recommendation.
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