Heidelberg Materials details Permanente Quarry operations, creek restoration and reclamation plan; draft EIR expected January 2026

Heidelberg Materials representatives, county regulators and community groups briefed residents at a Cupertino town hall on ongoing activity at the Permanente Quarry, the kickoff of a long‑planned Permanente Creek restoration and the county’s review of a reclamation plan amendment that could bring millions of cubic yards of off‑site fill into the quarry.

Supervisor Margaret Abe‑Koga opened the meeting by saying the panel would address current operations, the creek restoration and the reclamation plan amendment. Rob Salisbury, principal planner for the Santa Clara County Department of Planning and Development, said the company’s reclamation plan amendment application has been deemed complete and that the county is preparing an environmental impact report (EIR). "We expect the draft EIR to be ready for public circulation in January 2026," Salisbury said, and that the draft would be circulated for a 45‑day public comment period before a final EIR and planning‑commission review, currently anticipated in late 2026.

Heidelberg Materials described four ongoing activities at the site: aggregate production (currently operated under a lease by Vulcan Materials), the Permanente Creek restoration project, pre‑demolition work on cement‑plant structures and preparation for long‑term reclamation. Sanjeet Sen, senior environmental manager for the site, said the creek restoration will remove mining overburden, concrete channels and culverts, widen the channel by about 9,000 linear feet within the property and add riparian native vegetation designed to the California Department of Fish and Wildlife restoration manual. "We will give them every opportunity," Sen said when asked whether fish could return after restoration.

County and state regulators described their oversight roles. Jessica Watkins, chief of the groundwater protection division at the San Francisco Bay Regional Water Quality Control Board, said Heidelberg enrolled under statewide waste discharge requirements with a notice of applicability issued in March 2025 and that the board will review annual reports and may inspect construction phases. Nathan Veal, hydrogeologist with the board, and other speakers described the need to develop acceptance criteria for imported fill so that materials placed in the pit protect groundwater and surface‑water beneficial uses.

The reclamation plan amendment as proposed would change several elements of the existing plan, officials said. Salisbury noted the application proposes to remove a southern area across Permanente Creek from the reclamation boundary and to revise the planting palette. The most substantial technical change is the proposed import of large volumes of off‑site material: the application describes approximately 30,000,000 cubic yards of imported "clean fill" and roughly 10,000,000 cubic yards of on‑site material to backfill the main pit. Heidelberg, represented by Greg Ronzka and Sanjeet Sen, said a mix of on‑site materials and imported low‑permeability material and topsoil would be used to achieve slope stability, capping and revegetation objectives. The county and water board said they will review the criteria for acceptance and sampling protocols for any imported material.

Panelists described technical and community issues the EIR will examine. Brian Malone of Midpeninsula Regional Open Space District and water‑board staff raised concerns about selenium in mined rock: when rock is placed above ground it can expose material to water and increase leaching risk. Malone pointed to a 2020 conceptual site‑model report (on the county website) that evaluates geotechnical and chemical data. Water‑board staff said those data and the closure plan will inform criteria for what qualifies as acceptable fill.

Slope stability and interim protections were a central concern. David Leifert of Midpen said monitoring since early 2022 shows movement and expanding landslide activity in the northwest wall and West Material storage area. County staff said the EIR and subsequent approvals will evaluate interim stabilization measures; Heidelberg described two principal engineering responses under consideration — laying back steep slopes or constructing buttresses using suitable material — and said ongoing monitoring and geotechnical analyses will guide decisions.

Residents raised truck traffic, noise and emissions as immediate local impacts. Cupertino and Heidelberg representatives said the aggregate operation begins early in the morning and that the first trucks typically leave about 4:30 a.m.; the company said it has relayed recent nighttime noise complaints (brakes squealing, early departures) to the aggregate tenant, Vulcan, for corrective action. County planners said an import program on the scale discussed could generate large numbers of truck trips (county estimates discussed in the meeting referenced up to ~600 truck trips per day for some import scenarios) and that the EIR will quantify emissions, noise and traffic impacts and evaluate mitigation, including rail transport as a lower‑emissions option if logistics allow.

Several agencies outlined monitoring and success criteria. The county noted reclamation bonds and long‑term monitoring requirements: restoration and reclamation plans include success metrics for vegetation survival and limits on invasive species; the county must accept those monitoring results before bonds are released. The air district described jurisdiction for asbestos notifications and fugitive‑dust controls; the county noted demolition permits and the building department process for taking down roughly 35–40 structures at the former cement plant.

Heidelberg said it expects union labor to be used on many projects at the site — aggregate processing, creek restoration, demolition and reclamation — and said it is open to community discussion about longer‑term uses of the property after reclamation. Midpen emphasized that much of the property outside the reclamation area contains high‑value habitat and that preserving wildlife corridors across the site is a priority.

Next steps: the county is completing scoping and preparing the draft EIR, which Salisbury said the county expects to release for comment in January 2026. When the draft EIR is circulated the public will have a formal opportunity to submit written comments; county staff said annual updates will continue in planning‑commission meetings and via the county’s interested‑parties list and Supervisor Abe‑Koga’s newsletter. Officials repeatedly urged residents to sign up for county and supervisor updates and to use the EIR comment period to raise technical and community concerns.

Discussion vs. decision: the meeting provided updates and clarified regulatory roles; no formal approvals or votes were taken. Regulators and Heidelberg outlined data, monitoring and permit steps that will determine whether and how the reclamation plan amendment is permitted and how restoration work is carried out.