The Reach 11 Dikes Modification Project is one of the largest slurry cutoff wall excavation and interlocked vertical geomembrane installation projects in the world. The project involved the installation of an impervious cutoff wall placed through the center of the dikes for 13.5 miles to depths up to 50 feet. The dikes originally were constructed in the early 1970’s to prevent desert floodwater from flooding the metropolitan area and crippling the Central Arizona Project Canal. The canal is a segment of the entire canal system in Arizona that supplies water to Phoenix and Tucson from the Colorado River. Barnard utilized innovative techniques to complete the project six months ahead of schedule.