Seepage and Contraction Joints in Concrete Canal Linings

Contraction joints in concrete canal linings are often provided with waterstops or joint sealants on the assumption that the cost of these provisions will be justified by a corresponding reduction in water lost to seepage through the lining. However, little evidence presently exists in the literature to support this conclusion. Seepage rate from a large, concrete‐lined canal with unsealed contraction joints was evaluated through full‐scale field testing. Testing consisted of water level and evaporation observations for a ponded 6‐mi (9.6‐km) length of the Santa Rosa Canal over a nine‐day period. The observed seepage rate is compared with seepage rates reported for similar canals with sealed contraction joints. The comparison indicates that contraction joint seals have little significant mitigating effect on canal seepage rate. The magnitude of typical joint sealing costs is discussed relative to the test results as an indication that the cost of sealing contraction joints in concrete canal linings may not be economically justified by a corresponding decrease in canal seepage.