Page 16 - Waterfall City Issue 2 February 2024

Waterfall City News

several challenges brought on by
significant stormwater coupled with the
area’s highly erodible sandy soils, which
was further compounded by substantial
infestations of invasive plant species
that disrupted the wetland’s natural
ecosystem.

“To overcome this, we worked together
with Balwin Properties to determine
the most cost-effective rehabilitation
methods. Of course, this meant we had
to be quite creative in some instances
for a solution that would underpin
sustainability,” says Spies.

We concluded that a combined
approach of engineering acumen and
using available natural resources on Repurposing the invasive trees, especially the black wattle, made for excellent natural barriers to curb
erosion. You will note heavy scouring taking place at this section and critical areas were ascertained for
site would be the best course of action. installation.
The engineering consisted of gabions,
designed to protect the main bridge
crossing with rocks to act as a sediment
basin where excessive silt is prevented
from entering the dam. Excessive silt
degrades water quality and negatively
impacts aquatic life.

Care had to be taken when it came to
invasive tree management. While they
undeniably threaten natural resources,
their roots did serve a purpose in holding
some of the embankments together.
Thus, we decided against uprooting the
trees in favour of systematic and slower
eradication methods, such as cutting This is a naturally made dissipation and attenuation structure. It will slow down the water coming in from
the top grate and allow for the deposition of silt and plant debris thereby allowing for other plants to take
and treating the various tree stumps hold and lessen the deep channelling taking place.

14 Waterfall City Issue 2 2024