The Power of One
By Chris Kelsey

Large panels, when possible, offer tremendous advantages, such as quicker installation and seams that have been created and tested in the controlled environment of a factory.

BTL produces a staggering 105,000-sq.-ft. single-panel of 20-mil geomembrane for a pond project

Geomembrane liners provide vital containment in all sorts of applications, from waste containment to potable water storage to industrial processing. The great degree of liquids, gases, soil types and structures involved in any installation or specific site use help dictate the selection of the particular geomembrane: polymer type, thickness, chemical resistance, etc.

Since geomembranes are manufactured for specific performance situations, and since manufacturing processes and geomembrane use are controlled by stringent testing regimes, manufacturing quality is rarely the main concern. Designer understanding of how to use a geomembrane is a greater concern. And preserving the integrity of the highly engineered membrane during installation is a concern.

When it comes to improving installation quality and project economy, one aspect that cannot be ignored is the high-quality fabrication one can achieve in the controlled environment of a factory.

Fabrication is the joining of geomembrane panels to create the single liner used on your site.

This pre-site controlled fabrication isn’t something all geomembranes are able to enjoy. All containment-oriented geosynthetics have their advantages over other types in certain applications and site-specific designs. But only flexible geomembranes are able to benefit from the economy and control in seaming that a factory fabrication environment can provide.

THE BENEFITS OF FORESIGHT

The final panel of 20-mil geomembrane weighed roughly 8,000 lbs--but took only 4 hours to fabricate in BTL's expansive new facility.

What can reasonably be done ahead of time, saves time later, of course. In the case of construction, pre-site fabrication can be an immense cost saver.

Pond construction is perfect for this.

Most pond construction and lining is what might be considered a commodity application. It’s more common and costs are expected to be lower. But that doesn’t mean it’s easier. Soils do not take universally to ponds, and in a construction environment in which water conservation is increasingly desired, if not required, liners fit the bill but are immune to misuse.

Poor liner installation can lead to high repair, replacement or litigation costs.

Expert, on-site fabrication technicians come with a high labor cost, and field seaming work can be delayed for many reasons, such as weather, seaming machinery problems, power supply issues, etc.; all of which increase final project costs.

For commodity applications, this is rarely allowed in a project budget.

But expert fabrication is possible, especially where an application permits the use of the right flexible material.

For the Wisconsin project, BTL fabricated, in its environment-controlled facility, 20 sections of 12 x 450 foot material to create the single, 450 foot long x 235 foot wide panel.

That’s 105,000 sq. ft., every seam of which comes with extensive testing support and quality assurance. You’d find that in field seaming too, but at a much higher cost and with higher risk because of the many unknowns and challenges associated with field-seaming (e.g., controlling seams on slopes and uneven terrain vs. the flat, ideal conditions of a professional fabrication facility).

The 8,000-lb. panel for this impressive project was fabricated in less than 4 hours, rolled on a core with an unroll strap and shipped directly to the site via a flat bed commercial transport. For the journey, the liner was wrapped in a protective geotextile and covered with a logo wrap.

The excavator/contractor of record was a man with whom BTL has often worked. He was well familiar with the strength of the PPL®20 geomembrane—a 20-mil-thick, 5-ply reinforced polyethylene liner—for containment applications such as this large pond, which was for a private hunting and fishing retreat called St.Nicks.

The material was sold through Lake and Pond Solutions of Wisconsin, one of BTL’s distributors.

Few companies have the capacity to produce such a sizable roll of material.

On the material selection side of things, the contractor was then able to offer a very durable membrane that could still be acquired cost-effectively because of the pre-site fabrication possibilities. Many 20-mil reinforced polyethylene geomembranes, the sort commonly used in this type of application, use one scrim (single ply) and coating on both sides of the membrane or a three-layer product. BTL’s product uses two plies of reinforcement and coats both sides in addition to the joining layer; thus, creating a five-layer product.

As for the factory fabrication work that BTL performed, it allowed the contractor to offer high-quality seaming integrity and fast installation. This massive panel was installed in just a few hours: again, without the need for a team of high-priced, on-site technicians or the risks that come with joining panels in uncontrolled, outdoor environments.

Pre-site fabrication provided high-quality material and seams without the premium price tag—exactly what this sort of application calls for.

BIGGER STILL

A panel this size is highly unusual in the industry. Not many companies have the capacity for it. It was actually the largest 20-mil piece that BTL has fabricated, but the company has gone bigger before with 10- and 12-mil products.

Tackling this large 20-mil panel order was in part made possible by the 84,000 sq. ft. facility BTL recently opened. That, it should be noted, was the second major production expansion for the company in the last few years.

Concerning time and money, the benefits of this sort of pre-site fabrication expertise are many.

Chris Kelsey is geosynthetica.net's editorial director. He may be reached at chris@geosynthetica.net. Your submissions and project subjects are welcomed.