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Concrete system offers canal liner protection
A ten-year canal lining study by the U.S. Bureau of Reclamation (USBOR) tested four canal types for a multitude of factors, including construction and maintenance costs, durability and effectiveness against seepage. One of the tested categories, “geomembranes with a concrete cover,” offered the highest long-term performance results.
“Different materials to protect canal liners had been tried in irrigation canals across the west over the past 15 or 20 years,” said Joe Kaul of Kaul Corporation, Presto Geosystems’ Western States representative and geosynthetics supplier. “One typical method uses low-cost earthen material like clay. Over time, however, these systems begin to crack and start to leak. It’s not a very efficient way to convey water.”
Kaul introduced the concrete-filled 3-D Geoweb system to the USBOR as an effective geomembrane cover solution. With over 30 years of proven success protecting geomembranes, Kaul was confident they could design and construct a better long-term solution with the Geoweb system.
Gary Kennedy, Superintendent with the Mancos (Colo.) Water Conservancy District, noted that the region had been rehabilitating its canal systems for a number of years. Regular lining material with a shotcrete cover was considered, as well as individual concrete tiles for several sites. Ultimately, the concrete‐filled Geoweb solution was chosen, as it would offer the best protection from expansion and contraction issues caused by freeze‐thaw cycles and reduce long‐term maintenance costs.
The completed concrete-lined irrigation canal is flexible and resistant to shrinkage cracks.
Unlike typical reinforced concrete, where whole sections can crack and uplift, the flexible nature of the Geoweb system allows it to flex and conform to minor subgrade movement. Concrete cracks are controlled along the line of the Geoweb cell walls. With the success of the Geoweb system as part of a “geosynthetics” solution (geotextile, geomembrane, Geoweb geocells), the USBOR and Bureau of Land Management see opportunities to incorporate this solution in more of their irrigation canals.
The geocell system controls concrete shrinkage cracks, allowing flexing and some movement. Also, its Cellular structure eliminates the need for steel reinforcement and expansion joints. Finally, the cells allow for a consistent concrete infill depth and use of a higher slump concrete, facilitating faster concrete placement.