This 3,500-acre former cement plant site could become housing, open space

The former cement processing plant site in the Santa Cruz Mountains near Cupertino could become a combination of housing and expansive open spaces. 

The site’s cement-making operations, once owned by Lehigh Southwest Cement Co., were halted over three years ago, and the Santa Clara County Board of Supervisors recently solidified the plant’s permanent closure through an agreement with Lehigh and partner Hanson Permanente Cement Inc., the Silicon Valley Business Journal reported.

Having faced numerous environmental violations that led to the plant’s shutdown, Lehigh’s parent company, Heidelberg Materials AG, is grappling with decommissioning and restoring the 3,500-acre site. 

The Lehigh unit is considering generating revenue in the short term by selling decommissioned equipment materials and producing concrete aggregate from existing materials, the outlet said.

Additionally, the company is exploring charging construction companies for disposing of clean dirt at the quarry.

Plans for the expansive site include housing development in the portion within Cupertino’s jurisdiction and a proposal by Heidelberg to convert much of the land into open space. 

The long-term plan encompasses steps such as filling the quarry, reshaping steep areas, reinforcing quarry walls, removing aggregate stockpiles, and reestablishing vegetation to prevent erosion. 

The transformation process is expected to span several decades.

While Heidelberg hasn’t indicated an intent to sell the property, their involvement will be integral to executing the restoration plan. The overarching goal, according to Santa Clara County Supervisor Joe Simitian, is to achieve substantial public benefit while respecting property rights.

— Ted Glanzer