Over 200 designers, engineers, manufacturers, fabricators,
students, academics, and association members attended the NAGS / GRI-19
Cooperative Conference held December 14-16, 2005, at the Flamingo Hilton
in Las Vegas, Nevada. After a full day of pre-conference gatherings (NAGS
and IAGI Board Meetings, IAGI General Assembly, GSI Focus Group Meeting,
Geo-Institute Task Force to discuss the developing document, Suggested
Practices for Reinforced Walls and Slopes, and Geo-Americas Organizing
Committee Meeting), an ice breaker was presented in the exhibit hall
on Tuesday evening.
Conference-goers started
the
morning
with GRI's first session, Use of Low Permeability Soils in Geosynthetic
Reinforced Walls. Five speakers comprised the session (see speakers
and papers below) followed by an enthusiastic panel discussion. There
was much cross banter on where the problems lie in relation to failure
- an age-old conversation. Dean Sandri caused a murmur in the crowd when
he said that there was no shortage of structural engineers in the process,
the problem is that "finding a geotechnical engineer is impossible!
Structural engineers are designing the walls, but they must have
a geotechnical background." He continued, "We aren't doing a good job
of policing our
industry! It's our own fault that these walls aren't getting built properly."
More backing and forthing...the blame, or culpability,
then jumped to the field and improper construction. Regarding
low permeability soils and failure, Michael
Simas argued quite eloquently - complete with slides - that he feels
it is not so much an internal
drainage design problem, but a construction/mulitple-stacking/compaction
problem.
While Barry Christopher agreed that yes, it is critical
to stack one block at a time, gravel fill, and compact as you go along...he
is "not seeing this dictated in the design." Ball in designer's court.
Don Armstrong of Anchor Wall Systems took the floor and disagreed strongly.
He said,
"The
specification
is there. It is a quality control issue. But just because you write
it - which we do - doesn't mean it gets done." Back to the field.
Jim
Collins, author of NCMA's Design Drainage Manual, stated, "We need
to change the contract method. We have to design walls for owners, not
contractors." Barry Christopher then noted, "We have to reverse
the practice." He is concerned that right now, the situation is "use
drains in these instances, and really it should be drains must
always be used - always - unless you can prove that you don't need it."
Roberto
Montalvo implored the audience to go to the source. "We need to
talk to the people in the field." Meaning, explain the "where
and why of the geosynthetic to the builder in the field. It's our responsibility!"
Quality control. Bob Koerner put it succinctly, "Poor construction
will defeat even the best of designs."
John Paulson got up and spoke on Chip Fuller's behalf
(he had lost his speaking voice to one very cold and windy last sailing
day of five). He read from Chip's notes,
"Assuming that we all violently
agree on these design issues, we collectively have a major problem
mentioned by Jim Collins and Roberto Montalvo...In 2006, I estimate
that over 10,000
SRWs will be built in the U.S. The vast majority of these are commercial
applications with no input from geotech engineers.
The SRW industry has taken on a life of its own, and in my opinion,
less than 1% of the
engineers stamping these plans will ever hear, or read, the valuable
comments and papers presented here. How do we change
the current model of price-driven engineering designs being done for
contractors and installed by non-qualified installers?"
Bob Koerner mentioned that Home Depot, a company that
will be needing SRWs in its geographically diverse potential
locations around the country, is taking action in this arena.
After the presentations were made, Thursday's panel
discussion focused first on how the engineering of heap leach pads is
"pushing the envelope." Rick Theil wanted to commend the forward
designs in heap leach pads saying, "it is some of the finest engineering
I have seen." He sees more slippage in landfills. There is a lower
factor of safety in mining, but there is less slippage, despite the
fact that there is no "difference in design philosophy."
Charley
Cobb, who works in mining and dams, disagreed, "The level of engineering
in mining is poor." He commented that because
the
heap
leach
pad was
not
a landfill,
the engineers push the envelope more, however he feels that care must
be taken into account because "they are still fairly sensitive environments."
A query from the audience brought up the question of
current monitoring instrumentation. Mauricio Ossa said that "one
thing that is not very well known is conductive liners." Rick Theil
added that the 'most exciting area is the geoelectric surveys. It is
nice to have conductive
liners,
but you don't need them. With the water lance or dipole methods, you
can find defects." One example he used was a case where holes in
a liner were found in under six meters of ore in Argentina.
Dhani Narejo expressed concern in putting all the proverbial
eggs in one basket regarding design and lab tests. "We see more damage
in a field test than a lab test. Limitations on punctures depend on the
field."
He suggests that one should "do a test fill, and see what it takes. Fill
material, drain cover, traffic, load - all are different each time. Trial
and error is the best design you could possibly have."
Getting back to factors of safety for existing and
new heap leach pads, Jay Swihart, mentioned that he is "not seeing any
huge factors of safety" and is now "concerned that we are at the limit
for the load of the pipe." Rick Theil answered by saying that while "most
designs have pipe now, the regulations to have them there don't exist."
He wonders if pipes are even needed. "We've probably overkilled the pipe
design." He then demonstrated, making a large circle with his index fingers
and thumbs, that when a pipe collapses, it makes two smaller pipes (bringing
his index fingers and thumbs together in the center). "It's probably
going to get crushed, but we design
the
flow
to take
that."
Below are the presentations made throughout the event.
Please click
here to order a copy of the proceedings.
Parametric Analysis of Reinforced Soil Walls with
Different Backfill Material Properties
By K. Hatami and R. Bathurst
Influence of Various Parameters on Seismic-Induced
Permanent Displacement of Geosynthetic Reinforced Segmental Retaining
Walls
By A. Kadayifci and E. Guler
Experimental Investigation of Geofoam Seismic
Buffers using a Shaking Table
By S. Zarnani, R. Bathurst and A. Gaskin
Landfill
Construction over Peat Deposits – A Case History
By T. Soong, R. Paajanen and X. Qian
Approach Embankment Supported by Geotextile
Reinforced Sand Platform over Vibro Concrete Columns- A Case Study
By R. Wilson-Fahmy, S. Hanna, and R. Mankbadi
Use of Geosynthetics for
Stabilizing Recycled Ballast in Railway Track Substructures
By B. Indraratna, M. A. Shahin, and W. Salim
Geosynthetic-Reinforced Column-Supported
Embankment Design Guidelines
By J. Collin, J. Han, and J. Huang
Theoretical Analysis of Bending Stiffness
Test of Geosynthetic-Reinforced Base Layer
By Z. Yuan
Interpretations of Behaviors of Reinforced Geotextile
Composites
By H.-Y. Jeon, S.-H. Cho, and W.-S. Lyoo
Probabilistic Analysis of Geosynthetic-Reinforced
Unpaved Road Subject to Subgrade
Variability
By P. Bourdeau
Comparison of a Mechanistic-Empirical Design Model
to Measured Performance for Base-Reinforced Pavements
By S. Perkins and. E. Cuelho
Design and Build of a Small-Scale MSE Wall:
January 2005 Geo-Challenge Competition
By E. Freeman (no paper)
Issues Adversely Impacting the Ability to Integrate
Geosynthetic Technology into Engineering Graduate
and Post-Graduate Educational Requirements
By B. Mackey
Full Scale Geosynthetic-Reinforced Column-Supported
Test Embankment
By A. Hassandi and T. Edil
The Short and Long Term Compressive Behavior
of HDPE Geonet at Different Inclined Conditions
By S.-S. Yeo and Y. G. Hsuan
Numerical Investigation of Geofoam Seismic
Buffers Using FLAC
By S. Zarnani and R. Bathurst
Examination of Metal Retention in Geosynthetic
Clay Liners Following Permeation by Different
Mining Solutions
By K. Lange
Use of GCLs to Control Leakage Through
Geomembrane Defects Under High Hydraulic
Heads
By C. Weber and J. Zornberg
Multi-Scale Assessment of Geotextile-Geomembrane
Interaction
By D. Kim and J. D. Frost
Geotextile Separators for Dust Suppression
in Gravel Roads
by E. A. Freeman and J. J. Bowders
Practical Construction Details
Used to Build an Instrumented
Flexible Pavement with Geosynthetics
by I. L. Howard and K. A. Warren
Geotextile Tube: Filtration
Performance of Woven Geotextiles
under Pressure
By K. Liao and S. K. Bhatia
Case History: Failure of
a Geotextile Turbidity
Curtain
By M. Harney and R. Holtz
Geotextile Biofilters for
Wastewater Treatment
By C. Yaman, J. Martin
and E. Korkut
Geotextiles
for Filtering Water and Oil Fluids
By J. Scott
An Evaluation of Potential
Clogging of Geonets
and Geocomposites Due to
Suspended Soil
Particles
By D. Narejo
Geosynthetics
Research and Applications
in the Mining
and Mineral Processing
Environment
By K. Renken,
D. Mchaina and
E.
Yanful
Current
Research on Dynamic Shear
Behavior
of Needle-Punched
Geosynthetic
Clay Liners
By P. Fox,
T. Morrison,
C.
Nye, J. Hunter,
and J. Olsta
Investigation
of PVC Liner
Leakage
in a
Very Large
Evaporation
Pond
By I. Peggs
and J. Duhalde
Impacts
and Limitations
of Quality
Assurance
on Geomembrane
Integrity
By B. Forget,
A. Rollin
and T.
Jacquelin
Lessons
Learned
from
a Geomembrane
Liner
Failure
in a
Cold Environment
By I.
Peggs
Leachate
Recirculation
and
Potential Concerns
on
Landfill Stability
By
R.
Thiel
and
M.
Christie
Aluminium
Migration
Through
a
Geosynthetic Clay
Liner
By
C.
Lake,
G.
Cardenas
and
G.
Gagnon
Use of Low Permeability Backfill Soils in Geosynthetic
Reinforced Walls and Slopes
Low Permeable Backfill Soils
in Geosynthetic Reinforced Soil Walls: State-of-the-
Practice in North America
by Barry Christopher
Geosynthetic Reinforced MSE Walls and Slopes with
Fine Grained Fills: International
Perspectives
by Chris Lawson
Full-Scale MSE Test Walls
by Richard P. Stulgis
Back Drainage Design and Geocomposite Drainage Materials
by Robert M. Koerner, Te-Yang Soong and George R. Koerner
Drainage Recommendations
for MSE Walls Constructed with Marginal Fills
by Dean Sandri
Use and Design of Geosynthetics
in Heap Leach Systems
Geomembranes Used in Heap Leach SX-EW Mining: A
Manufacturer's Perspective
by Mauricio Ossa
Heap Leach Facility Liner Design
by John F. Lupo
A Tale of Two Conditions: Heap Leach Pad versus Landfill
Liner Strengths
by Allan J. Breitenbach and Richard S. Thiel
Designing for Vertical Pipe
Deflection Under High Loads
by Mark E. Smith, Abigail Beck, Richard S. Thiel and Phil Metzler
Seismic Design/Analysis of Heap Leach Embankments
by Ellen M. Rathje (presentation only)
Continued Hot Topics
in Geosynthetics
Activites
in GSI-Korea – GCI-PCP of Geogrids
by Han-Yong Jeon
Long-Tern Plastic Pipe Stiffness
by Chiwan Wayne Hsieh, Chien-Chih Huang, and Jau-Bih Wang
Advances on
the Use of Geosynthetics in Hydraulic Systems
by Jorge G. Zornberg
Geosynthetic
Engineering Concerns from a Manufacturer’s
Perspective
by Boyd Ramsey
Geosynthetic
Manufacturing Concerns from a Consultant’s
Perspective
by Mark D. Sieracke
Design of Pressurized Liquid Distribution System for
Landfill Liquids Addition and Augmentation
by Xianda Zhao, Morgan Subbarayan and Te-Yang Soong
Geosynthetic Installation
Damage Testing - A Status Report
by Sam R. Allen
Aluminium
Migration
Through
a
Geosynthetic Clay
Liner
By
C.
Lake,
G.
Cardenas
and
G.
Gagnon
Geotextile
Separators for Dust Suppression in Gravel Roads
by E. A. Freeman and J. J. Bowders
Practical Construction Details Used to Build an Instrumented
Flexible Pavement with Geosynthetics
by I. L. Howard and K. A. Warren
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