The California Department of Toxic Substances Control (DTSC), pursuant to authority granted under California Health and Safety Code Chapter 6.5 and California Code of Regulations, Title 22, Division 4.5, Chapter 20, proposes to approve a Class 1* Permit Modification (Modification) for the Hazardous Waste Facility Permit. The purpose of the permit modification is to extend the closure period for 25 tanks.
The HGST Inc. facility is used for designing, developing and manufacturing computer storage devices. The processes utilized in these operations include photolithography, vacuum deposition, electroplating, chemical and vacuum etching, and precision machining. In January 2006, HGST consolidated its operations into the 158-acre central production area of the site (internally referred to as the Core Campus and initiated plans to redevelop the remainder of the previous campus for mixed commercial/residential occupancy (internally referred to as the Redevelopment Area). The environmental impacts of the consolidation and redevelopment were addressed in the Integrated Final Environmental Impact Report (IFEIR) for the Hitachi Campus and Mixed-Use Transit Village Project (State Clearinghouse No. 2004072110). The permit modification is for an extension of the closure period that originally was set to expire on August 17, 2020. The permit modification will extend the closure period for the 22 tanks to September 15, 2020. The permit modification will extend the closure period for 3 tanks to December 31, 2020. HGST must submit a certification of closure report in accordance with CCR, title 22, section 66264.115.