04-04-11 BPU RPT 08 - Laserfiche WebLink

Home

.�n. r 5 iZ re E F y Y RIVERSIDE PUBLIC UTILITIES Board Memorandum P U B L I I UTILITIES BOARD OF PUBLIC UTILITIES DATE: April 1, 2011 ITEM NO: 8 SUBJECT: SEISMIC UPGRADES AT LA COLINA AND HUNTER SUBSTATIONS—WO 1020992 ISSUE: Board of Public Utilities approval is requested for Work Order No. 1020992. RECOMMENDATION: That the Board of Public Utilities approve Work Order No. 1020992 in the amount of$266,240 for Seismic Upgrades at Hunter and La Colina Substations. BACKGROUND: La Colina Substation was originally designed and built in the mid 1960's. La Colina Substation's main overhead assembly is a steel box-type structure consisting of eight bays with an overall footprint of 50 feet wide by 102 feet long. Hunter Substation was originally designed and built in the early 1960's. Hunter Substation's main overhead assembly is an aluminum box-type structure consisting of six bays with an overall footprint of 24 feet wide by 150 feet long. Three of the six bays were constructed in the early 1960's. In the late 1980's,three more bays were added to Hunter Substation for additional capacity. Substation structures are designed to support various pieces of high voltage electrical apparatus (such as disconnect switches, insulators, bus,cable, lightning arrestors,etc.). During an earthquake,these substation structures, including associated foundations and anchor bolts, must withstand seismic loading while supporting the weight of electrical equipment. Recently, Stanley Consultants (Stanley) was retained to conduct a seismic analysis of the substation structures, including associated foundation and anchor bolts, at both La Colina and Hunter Substations. As part of the seismic analysis, Stanley modeled the main support structures at each substation using a structural computer program. The structural computer program was used to analyze each substation structure by simulating ground movement for an earthquake which applied lateral and vertical seismic loads to the substation structure,foundations, and anchor bolts. The results of the seismic analysis concluded that various parts of each of the substation structures, including associated foundations and anchor bolts,do not meet current seismic standards. In order for La Colina Substation to safely withstand seismic events, the structure and foundations for La Colina Substation require minor modifications. These seismic upgrades include the addition of structural cross members to the existing structure, and the reinforcement of existing foundations. Further analysis and evaluation is required to more clearly define the extent of the modifications required at Hunter Substation. Based on the results of the seismic analysis by Stanley, staff recommends that the seismic upgrades at La Colina Substation be completed. After determining the necessary modifications at Hunter Substation, staff will return to the Board of Public Utilities for approval of the seismic upgrades at Hunter Substation.