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The Garrison Dam National Fish Hatchery in North Dakota is a federal facility, which produces over 10 million native fish annually. Along with the role of providing fish for restoration stockings or balancing fish populations, the facility is also an attraction for tens of thousands of tourists annually. This project consists of lining five of their existing 66 fish rearing ponds with geosynthetics. The subgrade is a clay/sand mix which was graded, compacted, and cleared of any rocks, roots and other potential penetration hazards prior to arrival of International Cover Systems on-site to install the geosynthetics. Each of the five ponds were lined with six specifically factory fabricated panels for ease and speed of deployment. In addition, 205 factory fabricated ballast tubes ranging from 32 to 46 ft long were filled on-site with Peastone and placed on the deployed geomembrane panels after they were seamed and quality tested. The geomembrane was secured with battening to all of the associated concrete structures.
Originally, the designer for this project specified a 45mil thick reinforced polypropylene (45RPP) geomembrane due to its UV resistance in long-term exposures, high puncture resistance, tear strength, cold cracking resistance, and potable water qualities, which are compatible with fish rearing. Due to supply chain issues after the project was awarded, 45RPP geomembrane was not available for the duration of the specified project timeframe. As a result, project engineers substituted Viaflex Dura-Skrim N45 45 mil thick reinforced linear-low density polyethylene (LLDPE) geomembrane for the pond liner system. Not only was the LLDPE geomembrane available within the project timeframe scope, it also shares similar properties that originally attracted the designer to the 45RPP geomembrane.
The use of factory fabricated geomembranes and ballast tubes aided the project in a variety of ways. This project was originally scheduled for installation in August 2021,giving the installation crew many hours of weldable temperatures and weather. Due to the aforementioned supply chain issues of the originally specified geomembrane, the project was delayed until late October 2021. Temperatures in Riverdale, North Dakota during late October limited welding operations to only a few hours per day. As a result, it was important to minimize the amount of field geomembrane seaming, which was accomplished by factory fabricating large panels. Deploying the geotextile underlayment and large fabricated panels for the first part of the day allowed ICS to perform quality welding operations when ambient and sheet temperatures reached optimal levels. Limited field welding due to the use of large fabricated panels minimized the duration of welding each day and allowed the project to be completed with the highest quality even in late October.
Another challenge that was mitigated by using fabricated geomembrane panels and ballast tubes is the strong North Dakota winds during late October. Ballasting was required as soon as the geomembrane panels were deployed to maintain control of the geomembrane in the windy conditions. Fabricated geomembrane panels reduced the time required to secure the geomembrane with ballast, saving valuable time, and keeping all crew members safe from what can be a dangerous situation with an unballasted geomembrane in a windy environment. All ballast tubes were factory fabricated, shipped to the site, and filled with Peastone in place.
The FGI is proud to highlight our members' projects utilizing fabricated flexible geosynthetics. Check out some
of the creative projects, understand why certain products were selected, and read the project descriptions
as well as the important lessons learned.
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An interactive list of welding equipment and products for
fabricated flexible geomembranes. Read more
On March 2, 2023, Tim Stark visited the replacement liner and floating cover system for the El Toro Reservoir in Mission Viejo, California. This is a joint reservoir project between three water districts that is providing emergency water supply, storage, and cost savings to south Orange County water customers. The reservoir holds 275 million gallons (1.04 billion liters) of potable water. The reservoir was originally constructed in the 1960’s as an open reservoir. The first geomembrane floating cover was installed in the early 1980’s. In 2001 a composite geosynthetic liner and reinforced polypropylene floating cover was installed. After 20 years, the existing liner is being augmented with a new 60 mil (1.5 mm) CSPE geomembrane that is being placed on top of the existing 70 mil (1.8 mm) reinforced polypropylene (rPP) geomembrane, which is still in intimate contact with the underlying subgrade (see Figure1). The resulting bottom liner system is shown in Figure 2.
The main impetus for the project is replacing the 45 mil (1.1 mm) rPP floating cover system, which had exceeded its service life. The old cover system is being discarded and replaced with a 45 mil (1.1 mm) CSPE geomembrane based floating cover based on a requirement for an extended 30 year weathering warranty and long term material history. The project involves installing about1.1 million square feet (102,000 square meters) of geomembrane for the bottom liner system and about 1.15 million square feet (107,000 square meters) for the floating cover system as well as updating the reservoir interior valves, site drainage piping, and electrical upgrades. Douglas Hilts of Hilts Consulting Group is the design engineer, and the Layfield Group is the fabricator and installer of the liner and floating cover system geosynthetics. This project illustrates the advantages of factory fabricated panels because one panel extends from the top of the reservoir to the floor down slope over 325 feet where it is seamed with floor panels.
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.
New Board to Serve 2023-2025 Term
Congratulations to the following seven individuals for being elected to the FGI's Board of Directors for the 2023-2025 term:
President – Patrick Elliott (Viaflex/Colorado Lining International)
Treasurer – Ray Peebles (Cooley Group)
Secretary – Brian Fraser (Layfield Geosynthetics)
Board Member - Todd Harman (Hallaton)
Board Member - Doug Hilts (Hilts Consulting Group)
Board Member - Maya Innis (International Cover Systems)
Board Member - Duff Simbeck (Simbeck and Associates)
The FGI is dedicated to advancing the use of fabricated flexible geomembranes through education, research, and technology transfer. The FGI is a consortium of manufacturers, fabricators, installers, designers, regulators, and material suppliers of fabricated flexible geomembranes.
Use our Excel calculator to learn what measurements are needed to properly plan for your pond liner project.
MoreFGI, ASTM and IAGI material specifications in one place for your reference and convenience
MoreA comprehensive guide to industry and our member material offerings for fabricated geomembranes.
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