After 20 years of publishing, Geosynthetica has a lot of content in its archives. This interesting photo of Dr. Ian D. Peggs shows him conducting an integrity survey while suspended from a crane. Engineers, installers, and CQA professionals so often have to work in fascinating—and at times, highly challenging or outright frightening—locations. We asked Dr. Peggs if he might offer up a few notes about this particular situation. – Chris Kelsey
GEOMEMBRANE INTEGRITY SURVEY FROM A CRANE
Ian Peggs writes: This was in a concrete basin of a wastewater treatment facility at a potato processing plant in Idaho. Conductive geotextile had been installed under the geomembrane to facilitate the water lance survey. An interesting challenge for me was to learn blind crane directions (boom up, boom out, left, right) with no visible hand signals to the crane operator outside the basin. Also, I discovered that whenever I touched the frame of the basket I got a leak signal—as contact to ground was made through the crane cable and the crane.
Despite the challenges this peculiarity posed, the water lance method integrity survey worked well.
Newer equipment has been developed since this survey was conducted, but I don’t know if the heightened data collection on today’s equipment would be any better for conducting a survey for this particular type of installation alignment. Perhaps if the basket that the survey operator was suspended from could be lowered and raised quickly (without threatening the operator’s safety or grinding the basket against the geomembrane) a roller probe (water puddle integrity survey) could be pushed against the wall. It’s an interesting thought.
Regardless, this was an interesting integrity survey to conduct. It’s always of value when you can learn or experience something new during what is otherwise standard work.
Dr. Ian D. Peggs, P.E., P.Eng is the former president of I-CORP INTERNATIONAL. He retired from his corporate role in early 2020. Dr. Peggs remains open to communication from the field. Visit his website: www.geosynthetic.com.