Addressing issues at Lehigh Quarry and Cement Plant

We have worked closely with other County departments to monitor the activities at Lehigh Quarry and Cement Plant.  We investigate and take action when Lehigh breaks the law.  For example, we researched and wrote a report about all the violations at the Lehigh Quarry and Cement Plant from 2012 through 2021.  We also analyzed whether the Lehigh cement plant had created a public health and safety nuisance.  In December 2022, we presented the report to the Board of Supervisors and explained the actions the County could take in response to the violations and any potential nuisance, including possibly modifying or revoking the County use permit that allows the Lehigh cement plant to operate. 

After that, we took the lead in negotiating and drafting a binding agreement with Lehigh for the permanent closure of the cement kiln at Lehigh’s cement plant.  The cement kiln was the single largest source of air pollution at the Lehigh property.  Under the agreement, Lehigh gave up its rights under its cement plant use permit to ever operate a cement kiln on its property again.  This Agreement was approved by the Board in August 2023. 

We have also worked with other County departments and outside agencies to address water pollution issues at the Lehigh quarry.  The Regional Water Quality Control Board has required Lehigh to clean up and abate Lehigh’s pollution of Permanente Creek with concrete and other wastes.  We advised the Department of Planning and Development relating to Lehigh’s resulting application to restore Permanente Creek to a natural habitat.  This included assisting with the preparation of a Supplemental Environmental Impact Report to make sure the restoration project complies with the California Environmental Quality Act. 

Looking to the future use of the Lehigh site after mining stops, we have collaborated with the City of Cupertino to develop a Joint Policy Framework Agreement Regarding the Restoration and Potential Future Development of the Lehigh Quarry Property.  This Joint Policy Framework Agreement was adopted by the Board of Supervisors and Cupertino City Council in June 2023.  Under the Agreement, the City and County agreed to work cooperatively with each other and other regulatory agencies to make sure that the Lehigh property will be reclaimed, restored, and cleaned up in a timely manner and consistent with all laws and regulations.  The Agreement also requires that any future development of the Lehigh property will benefit the local communities and maximize environmental and natural resources conservation benefits.