Decade of violations documented at Silicon Valley cement plant


A controversial Santa Clara County cement plant has accumulated more than 2,100 violations from different regulatory agencies over the past decade, according to a new report.

Supervisor Joe Simitian recently announced the county has compiled the first comprehensive list of all local, state and federal violations that took place at the Lehigh Southwest Cement property between Jan. 1, 2012 and Dec. 31, 2021. The company was fined more than $12.7 million over the past decade for alleged violations, including the discharging of wastewater and excess emissions that increased air pollution.

The Lehigh plant—also referred to as the Lehigh Permanente Quarry and Cement Plant—sits on 3,510 acres spanning unincorporated Santa Clara County, Cupertino and Palo Alto. It’s the only major cement producer in the Bay Area.

Lehigh, which has had a permit to operate since 1939, applied with the county in 2019 to expand mining operations in the surrounding hillsides. This upset local environmental advocates and residents who for years have expressed concerns about soil erosion, emissions and noise pollution caused by company trucks traveling to and from the plant. Lehigh’s application triggered an environmental review, which is on hold as the company makes revisions.

Simitian requested the county compile a complete record of violations at the plant earlier this year, saying it’s important for residents to have a “one-stop shop” to find information about violations imposed on Lehigh by the 14 local, county, state and federal regulatory oversight agencies. Most of the violations and citations stem from the San Francisco Bay Regional Water Quality Control Board, the U.S. Mining Safety and Health Administration and the Bay Area Air Quality Management Board.

Simitian noted more than 100 serious violations were documented in the report.

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“I can only conclude that if this record of violations is simply considered to be the cost of doing business, then we can’t afford to have these uses continue for another decade,” Simitian said in a statement.

He added Lehigh was not forthcoming with information requested by the county and questioned whether the company’s lack of cooperation constitutes a violation of the county’s 2012 reclamation plan for the site.

Lehigh spokesperson Jeff Sieg told the company is committed to operating in a safe and environmentally responsible manner. He said the company disagrees with the characterization that Lehigh has not been transparent or worked with the county to address concerns of non-compliance.

“The narrative provided by the county unfortunately misrepresents the true compliance status at the facility and does not accurately reflect the dedicated efforts of our employees who work in good faith to ensure compliance at the site every day,” Sieg said.

Cupertino Mayor Darcy Paul said it’s good to have all the violations consolidated in one report, but he isn’t surprised by the findings.

“There have been concerns over the years that not all those (environmental) requirements have been met in a particularly positive manner,” Paul told, adding it’s not practical to have a heavy mining operation near densely populated cities.

Paul said his constituents want to restore the site’s natural environment—a plan Simitian discussed earlier this year when he floated the idea of the county acquiring the plant.

He acknowledged closing the plant would potentially force local construction projects to import cement from sites outside the region, which may not be an environmentally friendly process. He said regional leaders could address this problem by building rapid transit to move materials.

Brian Schmidt, policy and advocacy director at environmental advocacy organization Green Foothills, said it’s alarming that even with the report, residents still don’t know the full history of environmental violations at the cement plant.

“It’s important to note that this is just the last 10 years—this quarry and plant has been operating for decades,” Schmidt told “Who knows what else has gone on there at the property, this is not the sum of everything.”

Schmidt is excited about the prospect of at least partially restoring the site to a natural state, noting it would be one of the largest open space reclamation projects in the South Bay.

“We’re definitely following it closely, and I think it could be an important environmental campaign,” he said.

Contact Eli Wolfe at [email protected] or @EliWolfe4 on Twitter. 

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