Geosynthetics June/July 2021 - 31

Conclusion
The use of a soil-reinforced layer as a
subgrade for a piggyback landfill ensures
that the leachate barrier system of the
new cell will remain functional over the
long term. The designed and selected
PVA reinforcement geosynthetic is a
high-modulus woven geotextile made
with high-tenacity yarns that exhibit a
tensile strength of 2,570 pounds-force
per inch (450 kN/m) at 6% strain. It
creates a uniform repartition of the load
on the old waste and controls the differential
settlements.
The high-tenacity yarns made of
PVA permit the reuse of the bottom ash
material (available on-site) as backfill
material on the product.
The methodology followed for the
design of the reinforcement is already
in use and described in several guides;
however, the implementation of a monitoring
system permits refining of the
calculation and assumptions considered
in the geotechnical model and confirm
the expected behavior of the structure.
References
Agency for Environment and Energy Management
(ADEME). (2005). " Guide méthodologique pour le suivi
des tassements des Centres de Stockage de Classe II "
( " Methodological guide for monitoring settlement in
nonhazardous waste landfills " ), France (in French).
ASTM D6992. (2016). Standard test method for
accelerated tensile creep and creep-rupture of
geosynthetic materials based on time-temperature
superposition using the stepped isothermal method,
ASTM International, West Conshohocken, Pa.
Bureau de Recherches Géologiques et Minières
(BRGM) (Geological and Mining Research Bureau).
(2020). " Guide de recommandations pour la
conception des extensions d'ISDND en appui sur des
casiers anciens " ( " Recommendations for the design of
nonhazardous waste landfill extensions based on old
cells " ), France (in French).
ISO/TR 20432. (2007). " Guidelines for the
determination of the long-term strength of
geosynthetics for soil reinforcement, " International
Organization for Standardization, Geneva,
Switzerland.
Nait-Ali, K. L., and Freitag, N. (2009). " Reinforcement
made of polyvinyl alcohol yarns: Effect of wet/
dry cycles and consequences on the design
in the framework of the French standards, "
www.GeosyntheticsMagazine.com
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Rencontres Géosynthétiques, Comité Français des
Géosynthétiques (CFG), Nantes, France, 181-188.
NF G38-064. " Utilisation des géotextiles et produits
apparentés-Murs inclinés et talus raidis en sols
renforcés par nappes géosynthétiques-Justification
du dimensionnement et éléments de conception "
( " Use of geotextiles and related products-Inclined
walls and slopes reinforced with geosynthetics-
Justification of the sizing and design elements " ),
Association Française de Normalisation (AFNOR), La
Plaine Saint-Denis, France (in French).
Olivier, F. (2003). " Tassement des déchets en CSD de
classe II : Du site au modèle " ( " Waste settlement in
nonhazardous waste landfills: From site to model " ),
Ph.D. thesis, Grenoble University, France (in French).
Seeger, S., and Müller, W. (1996). " Limits of stress
and strain: Design criteria for protective layers
for geomembranes in landfill liner systems, " Proc.,
Geosynthetics: Applications, Design and Construction,
Rotterdam, The Netherlands, 153-157. G
>> For more, search landfills
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FIGURE 9 Hydraulic settlement gauge
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