Your Liner Passed the Water Test. Will It Survive Diesel?

Most geomembrane failures don’t happen on day one. They happen eighteen months in, when the specified liner starts to fail containing a liquid it was never intended to contain.

Water containment is forgiving. Almost any liner material handles it. The moment hydrocarbons enter the picture — diesel, crude, hydraulic fluid, jet fuel, lubricating oil — the field of acceptable materials narrows sharply, and it narrows in ways that aren’t obvious from a spec sheet that leads with tensile strength and puncture resistance.

Here’s what the immersion data actually shows.

Hydrocarbons are the dividing line

E Squared runs 28-day room-temperature immersion testing across roughly 180 chemicals for EIA, PVC, and LLDPE-R FG. Across most categories — salts, alkalis, dilute acids, alcohols, glycols — the three materials cluster together. Sodium hydroxide at 40%: all three rated A. Calcium chloride at 30%: all three rated A. Hydrochloric acid at 20%: all three rated A.

Then you get to petroleum, and the cluster breaks apart:

A = little or no effect. B = minor to moderate. C = severe effect. X = no data, not likely to be acceptable. *Requires 36oz/42mil and above.

Same three materials that were interchangeable against caustic soda are now separated by the difference between “little or no effect” and “severe effect.”

Why PVC struggles here specifically

PVC’s flexibility comes from plasticizers — additives that keep the sheet pliable and let it conform to rough subgrades and complex geometry. That’s a real advantage. It’s why PVC panels can be prefabricated 10 to 15 times larger than HDPE sheets, and why they mold tightly to contours that would fight a stiffer material.

The vulnerability is the same chemistry. Organic solvents, oils, and diesel act on those plasticizers directly, drawing them out of the sheet. As plasticizer content drops, the liner loses the flexibility it was chosen for and turns brittle. UV exposure accelerates the same process, which is why PVC installations typically call for a soil or geotextile cover.

None of this makes PVC a poor material. It makes it a poor material for hydrocarbon service. For decorative ponds, buried tanks, and wastewater applications, the flexibility advantage is real and the chemical exposure isn’t.

Why the polyethylene answer isn’t automatic either

The conventional response to “my project has fuel exposure” is to reach for HDPE. It’s the long-standing default for aggressive chemistry, and it earns that reputation.

But it arrives with costs that get underweighted at specification time. HDPE is stiff — genuinely difficult to work around tight corners and irregular contours. Its thermal expansion coefficient is high enough to produce substantial wrinkling as temperatures swing. Seams are field-welded rather than factory-prefabricated, which puts more of your liner integrity in the hands of on-site conditions. And it’s susceptible to environmental stress cracking under concentrated mechanical loads.

For a landfill cell or a heap leach pad with simple geometry and a construction plan built around field welding, those costs are absorbable. For a tank farm with penetrations, sumps, and containment walls, they compound.

It’s also worth noting what LLDPE-R FG does and doesn’t do. It’s more pliable than HDPE and performs well across a broad chemical range, but the table above is unambiguous: it’s rated X against ASTM #1, #2, and #3 oils, and X against refined gasoline. Polyethylene family membership does not automatically confer hydrocarbon resistance.

Where EIA fits

EIA holds an A rating across crude oil, diesel fuel, ASTM oils, and petroleum hydraulic fluid, while retaining the flexibility and factory prefabrication characteristics that make PVC attractive for complicated sites. Grades are available to meet the requirements of ULC S668 for applicable fuel and oil chemistries.

That combination is the reason the PVC-versus-HDPE framing is often the wrong question. It presents a trade-off — chemical resistance or installability — that a third material largely resolves.

EIA is not universally superior. Check the full table and you’ll find chemistries where PVC outperforms it (benzaldehyde, benzene, calcium bisulfide) and plenty where neither is appropriate. Aqua regia, acetic anhydride, naphthalene, and 100% perchloroethylene are rated X across all three.

Three questions worth answering before you specify

What exactly is in contact with the liner, including trace constituents? A tank farm rated for diesel may see hydraulic fluid, lubricating oil, and degreasers in the same containment area. Specify against the most aggressive constituent, not the primary one.

What temperature will it actually see? All of this data comes from 28-day immersion at room temperature. Elevated service temperatures accelerate chemical attack. Desert installations with dark liner surfaces reach temperatures well above lab conditions.

How complex is the subgrade? If the answer is “very,” the installability difference between a prefabricated flexible liner and a field-welded rigid one is not a minor scheduling detail. It’s seam count, and seam count is failure probability.

Check your chemistry

The full 28-day immersion data for EIA, PVC, and LLDPE-R FG across roughly 180 chemicals is published in our PVC vs HDPE vs EIA comparison guide, along with the complete PDF for your submittal package.

If your chemistry isn’t on the list, or if your service conditions run hot, tell us what you’re containing and we’ll work through it with you.

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