May 2015, Vol. 70, No.5


Kubota Unveils Quake Resistant Ductile Iron Pipe

In 1994 when the Northridge Earthquake hit Los Angeles, more than 1,000 underground water lines were damaged at a cost of $41 million.

Earlier this year, under the direction of Los Angeles Mayor Eric Garcetti and officials of the Los Angeles Department of Water and Power (LADWP) and Northridge Hospital Medical Center, approximately 6,500 feet of high-tech Earthquake Resistant Ductile Iron Pipe (ERDIP) was installed on streets surrounding the hospital. The ERDIP installation is part of an LADWP pilot project that adheres to the mayor’s Resilience Plan and only the third ERDIP project in the entire United States.

Enter the Osaka-based Kubota Corp., which devised an interlocking system of earthquake resistant joint ductile iron pipe. The pipe’s innovative, segmented design provides flexibility that allows up to one percent axial movement and up to eight degrees rotation to deal with the strains associated with earthquakes, landslides and temperature changes. The pipe lengths bolt together via a rubber flange with its zinc-coated lengths forming an interlinking system that will rotate and flex, and not pull apart under pressure.

Kubota began exporting early on to contribute to stable supplies of water outside Japan. Thus far, it has exported iron pipes to more than 70 countries in the world. Kubota actively works on not only supply of pipes but also the design of pipelines.

The water distribution mains in this area were already targeted for replacement, but the added enhancement of the ERDIP will greatly benefit the medical center and the surrounding neighborhood by providing a more reliable network for clean drinking water and firefighting capability in the event of another major earthquake. Construction began in October 2014 and work is expected to be completed in December 2015.

“The main purpose of this project is to improve seismic reliability in the water distribution system, replace aging infrastructure, improve water quality and train LADWP crews in the installation of this pipe,” said Joe Castruita, LADWP Head of Water Distribution. “LADWP will begin construction on three more pilot projects this year at strategic sites critical to the reliability of the city’s overall water system.”

The ERDIP is manufactured by the Kubota has a slightly higher cost than the standard pipe that LADWP uses. As it would be cost prohibitive to replace all 7,200 miles of pipe in the water system with ERDIP, the department will focus ERDIP construction on sites that have been deemed critical to the function of the entire water system in the event of another major earthquake.

The estimated overall project cost for all five pilot project sites is approximately $10 million. The Northridge Hospital site has an estimated overall project cost of $5.2 million.

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