Geosynthetics July/August 2024 - 41

* Temperature of runoff; pollution of
waterbodies with heated runoff can
occur with riprap
* Temperature in and around TRMreinforced
vegetated swales are cooler
than hard armor channels that create
heat islands
* Stormwater quality improvements with
TRM-reinforced vegetated swales
* Infiltration with vegetation to keep
water within the watershed
* Carbon sequestration with vegetation
* Sod has been placed under and over
TRMs before (this would not work
with riprap)
* Vegetated TRM swales commonly
serve as beneficial pollinator corridors
* Wildlife habitat differences
* Less destructive installation with TRMs
* TRMs installations return sites to
preconstruction vegetated conditions,
not imported rock
* Shipping and installation; TRMs
require significantly less transportation
and use of heavy machinery
* Cost; riprap is more expensive to ship
and install (typical installed cost of
33% or more depending on region, size
of rock required, etc.)
In addition, the use of TRMreinforced
vegetation furnishes a soft
armor, value-engineered option to hard
alternatives by effectively reducing construction
times, material costs, equipment
requirements and most importantly,
improving water quality, groundwater
recharge capabilities and other sensitive
issues involving water quality.
Some TRMs are rated for slope applications
as steep as 0.5H:1V, which covers
a wide swath of project conditions.
According to ECTC specifications, TRM
categories have vegetated permissible
shear stress test values ranging from
6 lb/ft2 on the lower end of the TRM
performance spectrum to at least 14 lb/
ft2 vegetated permissible shear stress
test value on the high end of the TRM
performance spectrum.
The vegetated permissible shear stress
is from ASTM or other independent testing
the engineer deems acceptable. Largescale
performance testing involves limited
soil types and vegetated stands, thus
it is recommended that an appropriate
factor of safety be used in design and
product selection.
Other more specific applications where
TRMs have provided successful solutions
to challenging conditions in the past are in:
* Intermittent high flow channels
* Levees
* Landfill covers
* Shorelines (lakes, rivers, ponds etc.)
* Solar field drip lines and conveyances
* Pipeline slopes
* DOT slopes and ditches
* Fly ash pond covers
* Outfalls
* Dams
* Spillways
* Railbeds
These are only select examples of
where versatile TRMs provide high-performing,
green, soft solutions to help
protect natural resources.
ECTC members are committed to
providing high-performing TRMs and
other technologies. Please email ECTC
at info@erosioncouncil.org to learn more
about members, tools, services and sustainable
solutions the group provides.
In addition, there is a complete toolbox
of specifications, CAD files, installation
videos, fact sheets etc. online at the new
website: ErosionCouncil.org. G
>> For more, search ECTC at
GeosyntheticsMagazine.com.
FIGURE 2 TRM-reinforced vegetation on landfill
cap. Photo courtesy of ECTC.
FIGURE 3 Installation of turf reinforcement
mats (TRMs) with earth percussion anchors on
levee. Photo courtesy of ECTC.
GeosyntheticsMagazine.com
41
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Geosynthetics July/August 2024

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