Consolidation Grouting Operations for Kirkwood Penstock

Weaver, Kenneth D.; ,

Consolidation Grouting Operations for Kirkwood Penstock

by Kenneth D. Weaver, Woodward-Clyde Cons, United States,

Document Type: Proceeding Paper

Part of: Foundation Engineering: Current Principles and Practices

Abstract:

Kirkwood Penstock, which is part of the Hetch Hetchy water system of the City of San Francisco, California exhibited evidence of settlement and local extension following extraordinarily heavy rainfall that occurred 17 years after its construction. The remedial treatment measures undertaken to reduce the likelihood of continued or renewed episodes of settlement included displacement grouting. This type of grouting, rather than slurry grouting, was selected so as to minimize travel of the grout beyond the area to be treated. Grout hole drilling operations were conducted from a specially-constructed 'sled' that straddled the penstock, being mounted on concrete walls located on each side of the penstock. Reinforcing bars were placed in each hole prior to injection of grout, so as to help tie the inferred loose talus mass together. The results of slope indicator measurements made since completion of the remedial treatment indicate that no further settlement has occurred.

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