Repair of Seismic Damage to Aboveground Pipelines

The San Fernando Earthquake of February 9, 1971, caused severe damage to aboveground steel pipe sections of the two aqueducts serving Los Angeles. This damage resulted from different ground movement which displaced the pipe supports. The movements caused buckling and rupturing at a welded slip joint, separation of several mechanical couplings, and shifting of concrete anchor blocks on the 77-in. (195.6-cm) diam welded steel Second Los Angeles Aqueduct. The riveted 99-in. (251.5-cm) diam First Los Angeles Aqueduct was misaligned laterally and longitudinally. Repair to the facilities consisted of removal of buckled sections, installation of new saddle supports, replacement of mechanical couplings, and installation of rock anchors. Movement sensors were installed across mechanical couplings and load cells were attached to the rock anchors to measure changes in load. Recommendations are made to reduce potential seismic damage to aboveground pipelines to permit their continued operation following earthquakes.