Barnard Construction Co., Inc.

Owner:

Los Angeles Department of Water and Power

Scope Of Work

The original Haiwee penstock was riveted steel pipe built in the 1920s as part of the Los Angeles Aqueduct system that carries water from the Owens Valley to Los Angeles. The penstock starts at the toe of the south Haiwee Dam and runs approximately 10,000 feet south to a powerhouse at the bottom of Haiwee Canyon. In 1950, most of the upper penstock was replaced with 3/8-in.-thick, coated and lined welded steel pipe, and in 1968, the Rose Valley Los Angeles Aqueduct 2 (LAA-2) penstock was constructed and a wye branch connection was made to the Haiwee penstock. Then, in 1984, approximately 1,700 feet of the Haiwee penstock located upstream of the wye branch connection collapsed due to a vacuum event. The penstock was pressure inflated, which partially restored the penstock to its original shape. However, the restored section was extremely distorted and had many longitudinal creases and folds.

For this project, Barnard replaced the outdated and distorted steel penstock with FRP pipe, which is designed to withstand the normal operating pressure changes as well as accommodate surges and full vacuum conditions attributed to sudden emergency unit shutdowns or other system upsets. Barnard worked with Engineer Golder Associates and pipe manufacturer Ershigs, Inc. to complete design within 10 months. The project also included a tie-in to the LAA-2 aqueduct at the wye branch connection as well as the installation of fire hydrants, a penstock drain line, an updated cathodic protection system, and a stand-alone pressure and vacuum resistant carbon fiber lining system for several sections of the existing penstock, which remained in service.