Geosynthetics August/September 2021 - 9

METAL LEACHING
FROM GEOSYNTHETICS
Q: Geosynthetics are made from polymers that
use metal-based catalysts in their formulations.
Do geosynthetics have the potential to leach
metals into the environment?
A: I think the fair answer to this is yes, but the
potential risk is very small due to the long-term
stability of the polymers used in geosynthetics
and the very low concentration of such metals
in the formulation. There are many scholarly
articles on the web in this regard.
That written, I would like you to consider
the very large benefit of geosynthetics
(particularly geomembranes) as compared
to the relatively small risk that they pose to
the environment when serving as part of a
barrier for containment of waste. Note that
geomembranes, and, in particular, highdensity
polyethylene (HDPE) geomembranes,
have no natural equivalents to my knowledge.
Before work begins on any construction
project, contractors need to verify that the
selected geosynthetics are fit for use. They
must take responsibility for acceptance of
manufactured or fabricated materials and
products. Contractors need to verify that
the geosynthetics in question are listed as
approved (National Transportation Product
Evaluation Program, DataMine, Caltrans, etc.).
Geosynthetics are not allowed to be used
on sites until certificates of compliance have
been submitted and certified. In addition,
contractors must ensure that geosynthetics
are properly covered for protection against
damage prior to use (unless specifically
designed to be exposed) and that they
do not pose a risk to human health and
the environment.
The path to quality begins with resins and
masterbatches from which geosynthetics
are formulated. Suppliers of these polymers
have a commitment to customer service.
Most manufacturers have technical support
teams with expertise and experience to
address environmental challenges. They
conduct their operations in a safe, clean,
responsible manner, often conforming to
rigorous international quality standards. They
strive to do business in an environmentally
sustainable way and monitor their operations
to make optimal use of the resources they
consume while reducing emissions and
waste. Many are supporting members of
the Alliance to End Plastic Waste (www
.endplasticwaste.org). The products they
make contribute to a sustainable future
and cost less than alternatives.
www.GeosyntheticsMagazine.com
9
If this is not satisfactory to you, perhaps a
toxicity characteristic leaching procedure
(TCLP) test is in order. One can also perform
such a test on aged materials.
SERVICE LIFE OF NONWOVENS
Q: Where can I find literature on the useful
service life of nonwoven geosynthetic fabrics
installed in soils?
A: One of the best references in this regard is
from a manufacturer of nonwoven geotextiles.
It is:
SI Geosolutions (now Propex). (1997). Smart
Solutions, Technical Note, SM-404. " The durability
of polypropylene nonwoven geotextiles for waste
containment applications. " https://tinyurl.com/
GIGeosolutions.
I would start with this paper and then scour
the reference list for additional sources. The
above reference is nearly 25 years old but still
is relevant and available on the web.
https://www.tinyurl.com/ http://www.geokon.biz/geonet http://www.endplasticwaste.org http://www.GeosyntheticsMagazine.com
Geosynthetics August/September 2021

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