Lehigh looks to shrink, then close Permanente Quarry
SAN JOSE – Today, County Planning staff shared Heidelberg Materials’ newly proposed Reclamation Plan Amendment (RPA), which addresses the closure and restoration of the land at Permanente Quarry in the hills outside Cupertino, during the County’s Housing, Land Use, Environment and Transportation Committee (HLUET) meeting. The site is owned by Heidelberg Materials and operated by Lehigh Southwest Cement Company.
County Supervisor Joe Simitian, Vice Chair of the Committee, said he felt this latest proposal was a significant improvement on Lehigh’s 2019 application, with the updated 2023 RPA in better alignment with his three stated goals:
• Close the cement plant;
• Stop mining in the quarry; and,
• Begin the restoration and reclamation of the property.
The new RPA addresses contentious aspects of the 2019 proposal which would have amended the existing 2012 RPA. In its 2019 proposal Heidelberg put forth a plan to mine additional limestone from the area, and to cut back the slope of the north quarry wall for mining. Heidelberg had looked to set aside the County’s ridgeline protection agreement to accomplish these goals, a proposal Simitian characterized as “a nonstarter.” The 2023 RPA application, however, indicates an intention to preserve the quarry north wall ridgeline and to forego new mining.
“The review of this newly proposed Reclamation Plan Amendment will undoubtedly be a lengthy and thorough process,” said Simitian. “But what’s important here is that this new RPA reduces the quarry footprint, puts an end to the mining of limestone, and no longer ‘chops the top’ off the ridgeline.”
To protect the ridgeline and surrounding habitat that is part of the property, in 2021 the County and the Midpeninsula Regional Open Space District (Midpen) entered into a Memorandum of Agreement (MOA) to share enforcement of the ridgeline preservation easement (granted in 1972) that protects the land adjacent to Rancho San Antonio County Park.
Lehigh’s 2023 proposed RPA, if approved, would return the site to an open space condition with appropriate contours and landscaping. Activities planned in alignment with this goal include grading steep areas for stability, backfilling the quarry, buttressing quarry walls with fill, removing aggregate stockpiles, and revegetating to control wind and water erosion and assist in reclaiming viewsheds.
“Midpen is pleased to see that the proposed 2023 Reclamation Plan Amendment includes measures to preserve the ridgeline, which protects the viewshed and critical wildlife habitat, and is grateful for the County Supervisors’ partnership,” said Yoriko Kishimoto, Board President, Midpeninsula Regional Open Space District (Midpen) and past Chair of Midpen’s Lehigh Quarry Ad Hoc Committee. “We at Midpen will continue to advocate for the most environmentally preferred alternatives for reclamation.”
The proposed RPA seeks to reduce the reclamation plan boundary by roughly 30% (from 1,274 acres to 921 acres), and to remove areas of known limestone reserves south of Permanente Creek from future quarrying activity (by withdrawing a 353-acre mostly undisturbed area, which includes a small drill pad reclaimed area). Additionally, it will incorporate new California Surface Mining and Reclamation Act (SMARA) requirements enacted since the 2012 RPA, as well as new geotechnical stability information.
“I know that even though folks will be pleased by what’s not in this application – meaning opening up new areas to mining,” said Simitian, “there will still be plenty of concern about the potential environmental impacts of restoration – things like truck trips, in particular. The County will be taking a close look at all the environmental implications of Heidelberg’s proposal in the years ahead, and there will be multiple opportunities for the public to weigh in.”
In terms of next steps, the County will determine the “completeness” of the updated RPA application before moving on to environmental review. The RPA application along with the Environmental Impact Report will then be considered by the County’s Planning Commission, and if appealed, will go before the Board of Supervisors. Simitian estimates, “All of that could easily take until 2025 to complete.”