1. In-Situ Temperature Monitoring of Liner and Cover Geomembranes in Dry and Wet Landfills* - George Koerner is measuring the in-situ temperature behavior of liner and cover geomembranes and has installed multiple thermocouples for long term measurements in both wet and dry municipal solid waste landfills in Pennsylvania. The project has been extended into its 17th-year and has resulted in an extremely authoritative set of real-life data which is being used by many researchers in their geomembrane lifetime predictions. George has presented an updated paper in Berlin at the 10th IGS Conference.
2. Flow Behavior of Innovative Leachate Collection and Removal Systems (LCRS’s) – Several new geocomposite drainage systems are being compared to traditional geonet composites. The project is in its second year and will be a multi-year effort. It is likely that a Standard Guide will be developed on this topic.
3. Flow Behavior of Fully Degraded Waste* - This is a field project on investigating the drainage of highly degraded MSW placed directly on leachate collection systems. The leachate collection materials consist of both natural soils and geosynthetic drains. The experimental setup has been dismantled and a second paper was presented by George Koerner in Berlin at the 10th IGS Conference. A very recent draft White Paper was sent to members and “shot down” immediately. That said, we do indeed listen to our membership!
4. GT Flow Behavior of CCR Materials - This new laboratory project examines the behavior of four geotextile filters to fly ash, bottom ash, coal desulphurization material and well graded sand for control. George Koerner has just started the project.
5. Field Exposed Lifetime of Geogrids Used at the Facing of Landfill Berms - The facing of mechanically stabilized earth landfill berms (and other walls and slopes as well) is often using a wrap-around configuration leaving the geogrid exposed to the atmosphere. A project being conducted by George Koerner is presently investigating two different geogrid’s behavior over time. A 50-year time frame is envisioned! The long-term behavior will eventually be compared to UV laboratory exposed data as noted in Item #8 below.
6. Laboratory Exposed Lifetime of Geomembranes* - GSI is using three UV-fluorescent devices to estimate the projected exposed lifetime of six different types of geomembranes. Presently being incubated are HDPE, LLDPE, fPP, EPDM, PVC (N.A.) and PVC (Euro.). Some of the products have exposure times of 70,000 light hours at 70°C and a replicate set of samples are being incubated at 60°C. Some will take at least 90,000 light hours (~ 12.3 years). The third sequence at 80°C was started on 1/1/2010. They, of course, degrade much faster and are complete. Ongoing data is being reported to manufacturers and resin producers. GRI Report #44 is available on results to date. Our GSI-8 Webinar gives preliminary data using the elevated temperature incubation and extrapolation modeling for lifetime prediction in the lab and in the field.
7. HDPE Geomembrane Lifetime as a Function of Thickness - This often encountered question is being evaluated by exposure at 80°C in a QUV weathering device per ASTM D7238. Formulations are exactly the same and only the sample thicknesses vary. These thicknesses are 2.76, 2.44, 1.58, 1.08, 0.77 and 0.48 mm. Parameters being evaluated in this decade long study are change in thickness and presence of crazing or cracking. Time will tell!
8. Laboratory Exposed Lifetime of PVC (European) Geomembranes - Of late, we have been attempting to distinguish between PVC geomembranes manufactured in North America versus Europe. Of course, the differences are in the type of plasticizers used in the formulations as well as thickness. In this regard we have been evaluating five different European formulations for four years using three dedicated UV-fluorescent devices and the results are very impressive. The study is being conducted for CARPI Tech, a GSI member organization.
9. Laboratory Exposed Lifetime of Geogrids - The UV-fluorescent exposure of two different polypropylene biaxial geogrids which are used at the exposed faces of welded wire mesh MSE structures is ongoing. The various geogrids were incubated at 80, 70 and 60°C until halflife was achieved for strength and elongation. Laboratory lifetime predictions at 20°C as well as field predictions for Phoenix, Arizona are provided in GRI Report #44.
10. Laboratory Exposed Lifetime of TRM Filaments - We are also using UV-fluorescent exposure of four different turf reinforcement mat filaments to assess their lifetime capabilities. They have been incubated at 60°C, 70°C and 80°C. A final report to the manufacturer (Propex) has just been submitted.
11. Laboratory Exposed Lifetime of Geotextiles - A similar UV study as with geomembranes (Items 6, 7 and 8), geogrids (Item 9) and TRM filaments (Item 10) has been conducted on various geotextiles. Woven monofilaments, woven slit films, nonwoven heat bonded and needle punched types are included. In the latter are four different weights of needle punched nonwovens. All data and laboratory and field lifetime predictions are included in GRI Report #44.
12. Laboratory Exposed Geotextile Yarns - A new effort on behalf of a member organization (TenCate) is evaluating polypropylene yarns with and without long-term antioxidants. It will be interesting to observe differences in behavior insofar as long-term strength and elongation. As with all of our long-term exposure research, incubation is using UV-fluorescent devices per ASTM D7238.
13. Retaining Wall Failure Evaluations* - We presently have GRI Reports 38, 39, and 40 addressing mechanical stabilized earth (MSE) walls using geosynthetic reinforcement which document 82-failures. Our data base has now grown to 141, then 171, and now 257! Readers, we have a very serious situation in this regard! The failures are either excessive deformation or collapses. We have presented one-day courses on this topic along with inspector training and development insofar as a field inspectors certification program; see the certification section of this Newsletter/Report. We have just recently presented the findings at two geotechnical conferences; one in Williamsburg and the other in Hershey. A paper was published by the Journal of Geotextiles and Geomembranes in October, 2013 and the publisher (Elsevier) reports that 700 requests have been made to date. It was voted as being the best paper of 2013 by the journal.
14. pH Between Masonry Block Wall Units* - George Koerner has been measuring the pH between three types of masonry blocks for over six years to monitor the values. Concern here is over PET geogrids which are known to be sensitive to very high alkalinity environments. Indeed, the values started high, but over time are now down to eight and lower. George has a paper in this regard.
15. Landfill Failure Analysis - Since our originally reported paper on ten landfill failures in a 2000 publication, we have accumulated ten more. All 20-failures have been analyzed using the ReSSA Code and are now available to members and associate members as GRI Report #41. The latest failure in this regard is in Easton, Pennsylvania. It is under investigation presently.
16. Slow Pressurization of HDPE Geomembranes in Axi-Symmetric Testing* - The ASTM D5716 method of testing geomembranes in a 3-D axi-symmetric mode uses a pressure rate of 6.9 kPa/min (1.0 psi/min). While such a rate is reasonable for most geomembrane types, it is very fast for HDPE which is semi-crystalline and cannot readily stress relax. To investigate slower rates we have initiated a project with rates as low as 6.9 kPa/month (1.0 psi/month)! The last test, just now begun, is at a rate of 6.9 kPa/six months (1.0 psi/six months) and it will take about five years to conclude. A preliminary paper was presented at Geosynthetics ’15 in Portland.
17. Shrinkage of GCLs Under Wet/Dry Cycling - George Koerner has been evaluating shrinkage of various GCLs in boxes on the overhead roof of GSI. The study is on behalf of CETCO and may be extended for other manufacturers.
18. Temperature Behavior Under Different Geosynthetic Layers - Since exposed lifetime of geosynthetics is influenced by sunlight the lifetime of layers directly beneath the uppermost one (heat only, but no sunlight) is of interest. George Koerner has set up such a scenario on behalf of Watershed Inc., a GSI member.
19. Generic Specifications - A major continuing effort is ongoing with respect to the development and updating of GRI’s generic geosynthetic specifications. The current status of these specifications is as follows:
Completed and Available on our Website
GM13 – HDPE Geomembranes
GM17 – LLDPE Geomembranes
GM18 – fPP and fPP-R Geomembranes
GM21 – EPDM and EPDM-R Geomembranes
GM22 – Scrim Reinforced Barriers
GM25 – LLDPE-R Geomembranes
GM19 – Geomembrane Seams
GM28 – CSPE-R Geomembranes
GT10 – Geotextile Tubes
GT12 – Geotextile Cushions
GT13 – Geotextile Separators
GCL3 – Geosynthetic Clay Liners
GS15 – Geocells
GC14 – Turf Reinforcement Matts
Working; Available Upon Request
GNXX – Geonet Drainage Composites
Delayed; Available Upon Request
GGXX – Bidirectional Geogrids
GGXX – Unidirectional Geogrids
GCXX – Other Drainage Geocomposites
GSXX – High Strength Reinforcement Geotextiles
The complete set of completed specifications are available to everyone (members and nonmembers) on the open section of our Home Page. Please download and use them accordingly. There is a brief tutorial accompanying each specification. Also note that this is where the latest modification will always be available. Of note is that GRI-GM13 for HDPE geomembranes has been upgraded for stress crack resistance and asperity height.
20. Other GRI Standards - There are several GRI Standards in various forms of preparation. These include the following:
· A practice on field seaming inspection emphasizing the electrical leak location system (ELLS).
· Three standards on GCL joining so as to prevent/monitor panel separation.
· A guide as to recommended testing of drainage geocomposites.
· A practice explaining the use of MARV for geotextiles
· A transverse rib bending test for homogeneous geogrids