Geosynthetics February/March 2021 - 11

differences between engineered plastics
and single-use plastics, such as water
bottles. Engineered plastics are stabilized
to prevent degradation and designed to
perform as long-term or even permanent
solutions, whereas single-use plastics
are not stabilized, are discarded quickly
and begin to break down immediately.
Additionally, single-use plastics are
made from various unstable polymers
that break down into microplastics and
leach harmful chemicals. The HPTRM's
polypropylene has been found to contain
no leachable components (The Blastic
Project 2016-2018).
Of equal importance, the environmental benefits of the engineered earth
armoring solution extend into the product's useful life. Once installed, it helps to
decrease sedimentation and pollutants,
and encourages infiltration of water back
into the groundwater table. These are
two reasons why the U.S. Environmental
Protection Agency (EPA) has identified
systems that utilize HPTRMs as a best
management practice (BMP) for improving water quality.
The engineered earth armoring solution also features a patented trilobal
design that locks seeds and soil in place
to promote rapid root development for
long-term vegetation. This vegetated outcome supports a living shoreline, whereas
hard armoring can decrease streamside
vegetation and adversely affect fish populations. A vegetated shoreline helps to
maintain cooler water temperatures,
which is healthier for aquatic life habitats, than traditional hard armoring.
During installation, more than 2,000 sea
oats were planted within the system. The
solution's patented X3 fiber technology
helps hold roots in place, so they are not
washed away during rain events. The
vegetation establishment of the armoring solution is critical to long-term performance, providing a matrix of woven
HPTRM trilobal fibers, roots, stems and

The completed outfall with sea oats beginning to grow

soil to serve as a securing mechanism to
the slope face.
More than 2,000 square yards (1,672
2
m ) of engineered earth armoring solution with 6-foot (1.8-m) B2 anchors were
installed along the channel to reinforce
the outfall. The installation frequency or
spacing of anchors is a result of the slope
stability analysis. Anchors are typically
installed in a staggered pattern, creating a checkerboard effect. HPTRM roll
edge overlaps should be a minimum of
3 inches (8 cm), secured with anchors
according to the prescribed pattern
accompanied by securing pins on 12-inch
(30-cm) centers.
After installation, Hurricane Michael,
a category 4 hurricane, made landfall 60
miles (97 km) east of Oyster Lake. The
effects at this project location were winds
up to 80 mph (129 kph), storm surge, and
significant rainfall and flooding. The vegetated slopes of the outfall withstood the
extreme conditions, protecting several
beachfront homes, a Highway 30A bridge
and a portion of 30A's 19-mile (31-km)
bike path that runs along the famous
Emerald Coast beach communities from
Dune Allen to Seaside.
References
The Blastic Project. (2016-2018). www.blastic.eu/
knowledge-bank/impacts/toxicity-plastics. Accessed
11/30/20. G

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Geosynthetics February/March 2021

Table of Contents for the Digital Edition of Geosynthetics February/March 2021