The document discusses the foundation stabilization project for a new compression station of the Gujarat State Petroleum Corporation in Mallavaram, India, where problematic native soil and high water tables posed significant risks. Engineering India Ltd was tasked with implementing a cost-effective solution using PRS-Neoweb geocells to enhance the foundation's bearing capacity and protect the geomembrane from beneath. The innovative approach was designed for long-term reliability, cost-effectiveness, and quick installation while providing a solution that could tolerate minor ground movements.

1. Foundation Stabilization to Protect
Reservoir Geomembrane, India
THE CHALLENGE
The design of a new compression station for the GujaratState Petroleum
Corporation (GSPC) included a power station and four coolingponds.The facility
located in Mallavaram,Andhra Pradesh is partof GSPCs gas pipelinetransmission
network expansion.
However the native soil of the site was comprised of non-homogeneous softsilty
sand with a high water table. The subgrade had non-uniform bearingcapacity.
Hydrostatic pressurefrom the water and the self-weight of the earthen
embankments on this soil could causesignificantdifferential settlement. This would
lead to excessivestretchingof the lining, potential damage and even failureof the
reservoir.
A ground stabilization solution was needed to improve the bearingcapacity of the
pond beds, which would distributestresses more uniformly and limitdifferential
settlements. This was critical for reliable,long-term performance.
The consultingfirm, Engineering India Ltd (EIL), was tasked with coming up with a
cost-effective foundation improvement solution for the ponds.
PROJECT AT A GLANCE
Application
Stabilize subgrade of water reservoir
Subgrade/Soil
Siltysandwith veryhighwater table
Location
Mallavaram, Andhra Pradesh, India
Installation
2013
Quantity
45,000 m2
Client
Gujarat State Petroleum Corporation
(GSPC) is one of the leadingoil andgas
exploration, development and production
companies in India, and India's onlystate
government-ownedoiland gascompany.
Consulting Engineers
Engineering India Ltd
Contractors
Engineering India Projects Ltd
PRS-Neoweb Distributor
Gorantla Geosynthetics Pvt. Ltd.
ABOUT PRS
PRS is the world’s leadingsupplier of cost-
effective soil stabilizationsolutions.
Combiningunique proprietarytechnology
with specializedengineering expertise, PRS
delivers provensolutions for loadsupport,
slope andchannelprotection, earth
retentionandreservoir & landfill
applications.
With a global network offullyowned
subsidiaries andindependent local
distributors, PRS providesa full range of
end-to-endsupport services. Since its
establishment in1996, PRS has
implemented thousands of successful
projects inover 45 countries worldwide.

2. CASE STUDY
CONVENTIONAL SOLUTIONS
Alternative solutions to create a uniformlayer called for
extensive subgrade replacement with a thick cappinglayer of
quality aggregate. This solution was not cost-effective and
does not deal with the high water table. Cement stabilization is
too difficultto apply uniformly,its reliability over the long-
term is questionableeven in unsaturated conditions.Geogrids
can not providethe same level of ground reinforcement and
require imported higher costaggregate.
PRS-NEOWEB™ SOLUTION
PRS-Neoweb geocells were chosen to strengthen the reservoir
foundations,thereby providingprotection for the
geomembrane from underneath it. This differs from the more
common use of PRS-Neoweb, which is placed on top of the
geomembrane to protect it, usually with concrete infill. The
PRS-Neoweb layer on the pond subgradedistributes vertical
pressures laterally,thereby limitingdifferential settlement and
improvingits bearingcapacity.
PRS-Neoweb 150 mm height was laid outover a non-woven
geotextile and filled with 40 mm downsize aggregates. A layer
of 50 mm aggregate and 50 mm sand was placed as a cushion
between the PRS-Neoweb and the geomembrane. Two non-
woven geotextiles were laid under and over the geomembrane
for separation.The surfacelayer consisted of 150 mm thick
concrete pavingblocks setin 20 mm of cement mortar plaster
on top of a 75 mm layer of sand.
PRS-Neoweb was also utilized on the slopes of the earthen
embankments as well to maximize the geomembrane
protection of the earthen embankments.
CLIENT BENEFITS
 Engineering confidence – long-term reliability.
 Innovative solution – protecting the geomembrane from
the bottom up.
 Fast installation – easy and fast all-weather installation.
 Cost-effective – lower cost than alternatives.
 Multiple use – same PRS-Neoweb used for base
improvement and slopeprotection.
 Performance – guarantees long-term high bearing
capacity of the reservoir bed.
 Flexible solution – tolerates minor ground movement
without degradation or failure,includingseismic activity.
Foundation Stabilization to Protect
Reservoir Geomembrane, India
EN-CS-LS-1034
www.prs-med.com
* Design is validonly forNeoloy-based PRS-Neoweb™,
and not applicable toHDPEor fabricgeocells