Dedicated to advancing the use of fabricated geomembranes through education, research, and technology transfer.

Factory fabrication reduces field welding, reduces installation time and costs, allows modular construction and provides consistent seam and liner quality.

Geomembrane Test Method Videos Now Available

FGI has created FIELD AND FACTORY VIDEOS for the following
Test Methods:

ASTM D1239 Chemical Resistance, ASTM D1203 Volatile Loss, D5641 Vacuum Chamber, ASTM D4437 Air Lance Test,
ASTM D5994 Thickness (Textured), D5119 Procedure B Thickness (Smooth), ASTM D7408 Seam Peel Strength, ASTM D882 Tensile Properties & D7408 Seam Shear Strength, ASTM D1204 Dimensional Stability, ASTM D1790 Brittleness Temperature.


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Recorded August 30, 2022


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Design and Installation Detail Drawings Available

Details available for constructing a containment facility including pipe boots, concrete attachments, penetrations, and vent details.  Both PDF and DWG available.

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Mt. Woodson Reservoir Floating Cover Replacement - Ramona, California

Tensioned Cable Floating Cover removal and replacement for municipal potable water treatment and storage
45 mil CSPE geomembrane

The City of Ramona Municipal Water District had planned to replace an existing 29-year-old 45mil CSPE floating cover in the next two to three years.  However, as part of a strategic risk management review of their existing water storage facilities, they decided to move forward with this replacement in 2020.  As the material was reaching the end of its 30 year warranty period, the City had budget capacity and determined it important in terms of long term preventative maintenance of this reservoir to proceed with a new cover replacement a year or two early even though it was still functioning without tears or damage.  

The project required demolition and removal of the existing 29 year old CSPE geomembrane cover and the supply and installation of a new replacement 45 mil beige/tan CSPE geomembrane floating cover. The project faced several logistical challenges, including limited working area and not being able to take the exiting reservoir out of service during installation of the new cover system to prevent the stored potable water from being exposed to environmental contamination during construction. To fulfill this requirement, the existing geomembrane cover had to be removed simultaneously and in sequence with installation of the new geomembrane cover. This required welding the leading edge of the new geomembrane cover directly to the end of the old geomembrane cover material. As the old geomembrane was pulled off the reservoir, the new geomembrane was floated into place. The irregular shape of the reservoir, coupled with the limited working area, prevented deployment and welding of large prefabricated geomembrane panels along the edge of the reservoir, which would have accelerated construction. To address the tight constraints, Layfield constructed a 14,000 ft2 scaffold supported wood platform located at the northwest corner of the reservoir as a staging area for the geomembrane panels. This wood platform provided the additional work area required to stage, unroll, and weld the prefabricated panels for the new floating geomembrane cover systems.

The geomembrane cover system was tensioned around the perimeter with 5 ft (1.5 m) high mechanical weighted tensioning towers installed on 8 ft (2.4 m) centers for the original installation.  These steel tensioning towers were installed 29 years ago and required some refurbishing of components prior to being reused for the new cover system.  The tensioning towers include pulleys and weights that incorporate steel cables connected to a reinforced designed CSPE geomembrane strip attached to the cover geomembrane.  This perimeter cable system provides the required tensioning and buoyancy that allows the cover geomembrane to fluctuate with the water freeboard levels and support personnel on top of the geomembrane for maintenance and cleaning.


This was a challenging floating cover system because of the irregular shape of the reservoir, tight working space around the reservoir, and environmental conditions that had to be dealt with, such as not being able to expose the potable water to open air at any time during the construction.  The project team demonstrated creativity and engineering in their approach to resolve these challenges.  This installation would not have been possible without using a flexible geomembrane that allowed large factory/prefabricated panels to be supplied to the site to minimize the amount of field seaming and geomembrane handling.  The design and construction of the 14,000 ft wood scaffoldplatform was critical to allow sufficient workspace to unroll and weld the newCSPE geomembrane to the existing cover geomembrane before installation.  The project also proved that the new CSPE geomembranecould be welded to the 29 old CSPE geomembrane allowing the installation to becompleted without exposing the underlying potable water to the environmentduring construction.  


The 45 mil (1.14 mm) thick CSPE geomembrane for the cover system was prefabricated in Layfield’s Lakeside, California factory and shipped to the project site in custom size panels that are 35 ft wide without folds by various lengths allowing for the irregular shaped configuration of the reservoir to be covered.  Additional cover accessories, including float tubes, sandbags, and hatch doors, were also prefabricated in the factory.  The factory fabrication of large geomembrane panels significantly reduced the amount of field welding, field testing, patching, time, and project costs.    

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Tim Stark, FGI Technical Director

Tim Stark, Ph.D., P.E., D.GE., F.ASCE


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Geomembrane Guide

An interactive list of geomembrane products for various applications. Read more

The FGI Equipment Guide

An interactive list of welding equipment and products for
fabricated geomembranes. Read more

Temporary Landfill Covers - Design & Construction

Microplastics and Geosynthetics
Francesco Fontana, Technical Advisor at Manifattura Fontana SpA
Recorded on August 30, 2022

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Dr. Stark Visits Simbeck & Associates

On 8 August 2022 during atrip to San Diego, Tim Stark visited the offices and factory fabrication facility of Simbeck and Associates in Mancos (Main-Kiss), Colorado. Tim met with Duff Simbeck, Vice President of Simbeck & Associates (see Figure 1) to discuss current and future FGI activities, including the new operation and maintenance guideline for water reservoirs that Duff helped write, upcoming FGI webinars, MQA and CQA training, welder certification, and current University of Illinois research on action leakage rates, and carbon footprint calculator. Duff showed Tim some current factory fabrication projects and new fabrication capabilities for mainly public projects throughout the United States. Mancos, Colorado is the gateway to Mesa Verde National Park, which Tim toured the following day. Mancos can be accessed via Colorado Route-160, which is beautiful drive through the southern Rocky Mountains and includes the Wolf Creek Summit at Elevation 11,904 feet. If you are looking for a beautiful mountain drive or planning to visit nearby national parks, please stop by Simbeck & Associates at 38256 US-160 in Mancos and visit with the team at Simbeck & Associates.

Dr. Stark hopes to visit the facilities of all FGI members to better understand each member’s business and how the FGI can provide additional benefit to them. The FGI is an exciting advancement in the geomembrane industry and allows the Institute to focus on all geomembranes that can be factory fabricated.

FGI Summer 2022 Newsletter Now Available

Highlights include:

- FGI's New O&M Guideline for Water Reservoirs

- New Geo-Engineering Pop Quiz

- Exciting Webinar Schedule for Second Half of 2022

- Revised Geomembrane Defect Leakage Calculator

- Safety First Tip on Proper Safety Glasses

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