Straight Answers to Frequently Asked Questions About EPI's PVC Geomembranes
Q: What is a geomembrane?
A: A geomembrane is a waterproof construction material designed to keep liquids from leaking out from a specified area. Geomembranes are impermeable, which makes them the perfect barrier to combat seepage. There are a variety of applications and industries that use geomembranes, including the agriculture industry, oilfields, landfills, and more.
Q: What types of geomembranes are available?
A: EPI offers several types of custom industrial geomembrane liners. Some of our most common liners include:
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Q: Which geomembrane has the longest historical performance?
A: PVC, by a long shot! Since the 1950s, PVC has been effectively utilized on a wide scale in containment applications. In fact, studies by a United States Government agency on PVC, like this one on canal liners installed in 1968, prove that the physical property retention is in excess of the then current National Sanitation Foundation Standard 54 requirements.
Q: How do you use geomembranes?
A: Some of the common applications for geomembranes include the following:
- Coal Ash Systems
- Evaporation Ponds
- Green Roofing
- Floating Covers
- Heap Leach Mining
- Potable Water
- Decorative Ponds
- Process Water
- Secondary Containment
- Tank Liners
- Temporary Covers
- Wastewater Lagoons
- Landfill Covers
Q: How are geomembranes made?
A: Geomembranes are made from continuous sheets of material that can be as large as your project needs. If you need a liner that connects, the seams are heat-sealed together. The liners can be made from made different materials, depending on the application you need the liner for. At EPI, we pride ourselves on producing the highest quality geomembrane systems available, a prominent aspect of which is quality control.
Q: What type of quality control standards are in place for EPI's PVC Liners?
A: EPI is dedicated to using only the highest-quality raw materials, which either meet or surpass all standards as determined by the PVC Geomembrane Institute (PGI). EPI is considered the industry leader in creating testing methods using actual factory seam samples, and our "Quality Fabrication Control Manual for PVC" is lauded for its well-researched, detailed, and straightforward technical approach to PVC liners.
Q: Does EPI test actual factory seams?
A: Yes. Although many companies substantiate only the accuracy of their equipment settings, the team at EPI actually performs destructive seam tests from each and every liner that ships from our facility. To reach the pinnacle of geomembrane performance from the tests, EPI's in-house quality control program uses an independently-designed statistical process control sampling method which guarantees the tighest industry standards.
Q: Does EPI engage in any performance testing?
A: As pivotal as index testing and fabrication consistency are, actual field performance is the ultimate liner test. For several years, EPI has conducted systematic analysis of liners in the industry's only on-site test ponds. Various seaming techniques in both exposed and buried test plots are subject to a variety of technical performance criteria. In addition, EPI's in-house lab maintains on-going tests in many areas including loading, UV stability, friction characteristics and aquatic research.
Q: Can EPI air channel test its PVC field seams?
A: EPI has refined thermal welding technology to apply to PVC geomembranes. This state-of-the-art process allows EPI to employ exacting and precise air channel field seam testing. Thermal welding also allows EPI to complete PVC installations in more extreme weather conditions than are practical with traditional chemical fusion methods.
Q: What size are EPI's panels?
A: At EPI, our liners are often 200 feet wide and we have fabricated one-piece PVC panels of more than one acre in size. In fact, size is generally limited only by what panel weight can be efficiently handled in the field. Regardless of size, at EPI there is never a wide panel "up charge." And, our unique manufacturing process enables us to fabricate irregular shaped panels, reducing overall costs for irregular shaped containments. Our factory fabrication process also reduces field seaming requirements by as much as 80% over some types of liner materials, resulting in significant dollar savings.
Q: How does installation of EPI's PVC compare with clay or polyethylene liners?
A: Installation is faster and more economical with EPI's PVC.
|PVC From EPI||1||4 Pieces
(125' X 200')
|650 Lineal Ft.|
|Polyethylene||8-15||11-22'X420' Rolls||4620 Lineal Ft.|
|Natural Clay||14-28||200,000 Cu. Ft.
(7,400 Cu. Yds.)
Q: What thickness does the EPA recommend for PVC?
A: PVC is designed to provide strength and three-dimensional elongation without requiring the added thickness necessary to accommodate the grinding and welding procedures associated with polyethylene. In fact, recent federal landfill guidelines show that 30 mil PVC, 36 mil CSPE and 60 mil HDPE are functional equivalents.
Q: Will EPI's PVC stress crack?
A: EPI's PVC has an amorphous structure as opposed to the crystalline structure of polyethylene liners. Therefore, EPI's PVC is not subject to crazing or stress cracking from heating, high thermal expansion, or localized stress concentration geometries which adversely affect polyethylene liners.
Q: What is Geotextile Sewing?
A: Geotextile sewing is a method for joining geotextiles. Other popular methods include overlapping, stapling, and bonding. Sewing is the method used in situations when a more-substantial seam is required. There are different types of stitches used when sewing geotextiles. The two most commonly used are a simple chain stitch and a modified 401 lock stitch. EPI offers geotextile sewing along with related geosynthetic materials, contact us with any questions regarding geomembranes and geotextile sewing.
Q: How can I order EPI's PVC?