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Narrative: Seismic activity is a significant threat to buried infrastructure, particularly water systems. East Bay Municipal Utility District (EBMUD), serving more than a million customers in the San Francisco Bay area, developed water system damage prediction models to estimate the level of fragility of embankment dam reservoirs, tank reservoirs, and large diameter pipelines using multiple scenario earthquake events. The goal of the analysis was to understand the estimated level of water system damage for pre-event response planning purposes. This webinar will present the damage prediction results and an approach for other agencies to produce similar damage predictions models.
The following water system components were evaluated in the damage prediction model:
1. 29 embankment dam reservoirs.
2. 147 water distribution reservoirs consisting of 86 steel tanks, 58 concrete tanks, and 4 wood tanks.
3. Approximately 360 miles of large diameter pipelines consisting of welded steel pipe, reinforced concrete cylinder pipe, cast-iron pipe, and pre-tensioned concrete cylinder pipe.
EBMUD successfully modeled and documented the water system fragility results using six separate input scenario earthquake events. USGS provided the following scenario earthquakes:
1. Aagaard Mw 7.05 combined Hayward South and North,
2. Aagaard Mw 6.76 Hayward South,
3. ShakeMap Mw 7.05 Hayward,
4. ShakeMap Mw 7.05 Hayward Directivity Northwest (dirnw),
5. ShakeMap Mw 7.05 Hayward Directivity Southeast (dirse), and
6. ShakeMap Mw 7.9 San Andreas.
EBMUD obtained USGS grid XML and ShakeMap GIS shapefiles, which provided the necessary spatial ground shaking intensity metrics required for the damage prediction model. Along with ground shaking, EBMUD also acquired current hazard maps from the Bay Area to model damage due to liquefaction, landslide, and fault offset on the large diameter pipelines.
Roberts McMullin, P.E., Associate Civil Engineer, East Bay Municipal Utility District – Pipeline Infrastructure
Yogesh Prashar, P.E., G.E. , Associate Civil Engineer, East Bay Municipal Utility District – Materials Engineering
Roberts McMullin is an Associate Civil Engineer in EBMUD’s Pipeline Infrastructure Division in Oakland, California. Roberts is a registered professional engineer and has over 11 years of private and public engineering experience in pipeline design, infrastructure asset management, GIS management, and master planning. Roberts is the current Chairman of the Board for the Northern California Pipe Users Group (PUG). PUG is a non-profit organization that provides an educational forum for its membership share ideas and issues related to the pipeline industry. Members include: agencies, districts, consulting firms, vendors, suppliers, contractors, retirees, and enthusiasts.
Mr. Prashar is a registered civil engineer with 23 years’ experience in Los Angeles, Orange County and the San Francisco Bay Area. His experience includes project management, civil and geotechnical analysis, seismic assessments and construction inspection for a wide variety of public and private sector projects. Mr. Prashar has provided design and seismic analyses on numerous projects, monitored the performance of earth dams, and performed numerous liquefaction potential evaluations and settlement analyses of soft compressible soils and liquefiable deposits. Mr. Prashar has designed deep pile and pier foundation systems for structures including freeway overpasses, high-rise buildings and other commercial structures.
One of Mr. Prashar’s areas of expertise is using numerical methods for soil-structure interaction analysis applications in geotechnical earthquake engineering. He has used both 2D and 3D FLAC software (Fast Lagrangian Analysis of Continua) to solve static and dynamic problems for soil, rock, and soil structure interactions on over 100 projects of varying sizes. He has performed static and dynamic analyses of earth dams, buried tanks, port structures/wharves, soil reinforced walls, soil nail walls, retaining walls, tunnel box structures, pipelines, railroad tunnels and vibration analyses. Mr. Prashar has attended numerous specialty conferences on FLAC and has published 25 technical papers. He has developed three US patents on methods of stabilizing shallow landslides using creative full scale testing as well as three dimensional numerical simulation studies.
His more recent pioneering work includes using Geographic Information Systems (GIS) and Cone Penetrating Testing (CPT) results in the greater Oakland and Alameda area to develop seismic fragility of pipelines subject to liquefaction induced spatial differential settlements.
Keywords: Water, wastewater, pipeline, reservoir, tank, earthquake, seismic, liquefaction, embankment, dam