For a geomembrane to function properly and protect the environment from contamination, long-term stability is crucial. With a multitude of options and varieties of geomembranes available, it can be difficult to make an accurate, direct comparison. For example, when filtering by specification, geomembranes may be similar in physical attributes but have unique performance characteristics. In addition, geomembranes may be drastically different based on standards, units, sample sizes, test consistency and mode of failure. This can make performing direct comparisons between geomembrane options more difficult. However, there are two product properties that influence long-term performance on all types of geomembranes, and they are tear and coating adhesion.
Next to the yearly IFAI Conference, the Geotechnical Frontiers Conference is the largest conference I have been to for the geomembrane market. Unlike the IFAI Conference, Geotechnical Frontiers covers all geosynthetic materials and design applications, making it very appealing for almost any type of civil engineer.
Recent studies have demonstrated heavy metals and other toxins seep from unlined ponds into groundwater, causing environmental damage and posing health risks. Now, dozens of companies in industries like power generation involving coal ash are scrambling to quickly and effectively place geomembrane liners in their ponds to protect groundwater.
Nearly all geomembrane installations are fixed at the perimeter of the containment by burying the liner in an anchor trench or by attaching it to concrete (i.e., a collar wall, foundation wall, etc.). The standard approach for connecting the geomembrane liner to concrete is to use a batten. In this technique, concrete lags are set (i.e., drilled) into the concrete. These are placed on 6" or 12" centers at an engineer’s discretion. Neoprene or butyl tape is then placed between the liner and concrete, and a stainless steel, like 316 SS, or aluminum batten strip is placed over the liner and the lag bolts are driven through the batten, liner, and taped into the lag. The top of the detail is then sealed with a waterproof caulk (see Figure 1).
Design and industrial engineers rely on geomembranes to withstand the harshest conditions in a broad range of applications. They must be made of durable and chemically resistant materials to be able to optimally function as pond liners, floating covers, wastewater baffles and secondary containment—or to be used in other applications that require a long-lasting and impenetrable, yet flexible barrier.
Dr. Robert Koerner, professor emeritus of civil engineering at Drexel University, is a highly respected professional in both the geosynthetic and engineering communities. Earlier this month, he presented a webinar, “Wave (or Wrinkle),” covering unreinforced geomembranes, such as HDPE, and how geomembrane waves or wrinkles can be somewhat prevented and/or fixed.
Performing regular geomembrane inspections (where applicable) is critical and necessary for a successful long-term installation. Ongoing inspections can minimize field repairs and also prevent premature failure.
Many times, geomembrane leaks are caused by weather events or result from damage inflicted by personnel or equipment. As a result, the type of environment should be taken into consideration when deciding how frequently inspections occur. Some higher-risk locations that require more-frequent inspections include those that have surrounding trees and plenty of foot or vehicular traffic on the liner, subject to high winds, hurricanes or hail storms.
Once you’ve determined how at risk your geomembrane installation is based on environment, you should put an inspection and maintenance plan in writing. These are the steps you should follow to create an effective inspection and maintenance plan that will increase the service life of your geomembrane installation.
Geomembranes are the superior choice for containing valued substances (drinking water, petrochemical products, etc.) and for protecting the environment from harmful substances (wastewater, petrochemicals, etc.). But how do you protect your geomembrane liner?
The IWEA Annual Specialty Conference was held in October 2016 at the Forum Event Center in Fishers, IN. Annually, the IWEA (Indiana Water Environment Association) brings together the State of Indiana’s brightest engineers, operators and owners who are faced with the challenges of Indiana’s aging Infrastructure. Members share these challenges and offer affordable solutions for the greater good of Indiana’s aging pipes and infrastructures.
Throughout the day, presentations were given by individuals who successfully and financially solved Indiana’s Infrastructure problems.Two presentations are recapped below.