Lehigh Quarry Expansion Plan Threatens Views, Adds Traffic, and impacts Air/Water Quality


Los Altos and Los Altos Hills are in the epicenter of Lehigh’s plan to mine the protected ridgeline that separates Rancho San Antonio from the quarry. This mining area, within a mile of Los Altos Hills residents and about 2.5 miles from the track at Foothill College, would remove approximately 100 feet from the ridge for over a half-mile (3000 ft) along with its vegetation (for up to 2 years). A paper from the National Institutes of Health, Assessment of influential range and characteristics of fugitive dust in limestone extraction processes by CT Chang, claims that fugitive dust from limestone mining can travel up to 4.3 miles. The effects of fugitive dust are particularly worrisome because the Midpeninsula Regional Open Space District has previously detected exceedances in Particulate Matter and Chromium at Rancho San Antonio, likely due to mining. Consequently, visitors to Rancho San Antonio are already experiencing a diminution of recreational values at Rancho San Antonio and Lehigh's plan would make it worse.

Lehigh Cupertino’s proposed project would:

- Bring mining activities closer to homes, some within a mile of the quarry.
- Lower the protected ridgeline by 100 feet for over a half-mile (3000 feet) between the quarry and Rancho San Antonio. We are only 3 out of 5 votes away on the Santa Clara County Board of Supervisors of losing our ridgeline that is protected by the 1972 Ridgeline Protection Easement Deed.[2] When Lehigh purchased this property, they well knew the restrictions of this deed. Now they propose to lobby the Board of Supervisors to ignore the deed and ignore the promises made in their 2012 Reclamation Plan which preserves the ridgeline. Recall that in 2002, the quarry over-excavated and caused a landslide into Rancho San Antonio; the County brokered a quiet land swap between the two parties; there were no fines.

- Remove vegetation from the top of the ridge for up to two years.
- Increase traffic by at least 666 trucks per day for up to 30 years as a result of turning the quarry into a dump site and filling it with imported materials instead of using onsite materials (overburden at WMSA).
- Retain the 273-acre mountain of mining waste, called the WMSA, which had been destined to use as fill for the main pit in the 2012 plan. The edge of it can be seen as a brown line on the hillside that faces Los Altos. Additionally, this area would be raised by 160 feet.
- Add a new 60-acre quarrying area above Stevens Creek Quarry (Stevens Creek Quarry has also filed an application to increase their quarrying area by 77.5 acres and their 2015 expired use permit allows up to 1300 trucks per day).
- Intensify the use of explosives to 1101 tons per year, a reported 63% increase.
- Delay restoration of Permanente Creek, as required by Sierra Club Consent Decree, by 10 years.

Ongoing pollution and compliance concerns include that Lehigh:

- Is out of compliance with the Federal Clean Air Act and the Federal Clean Water Act for at least 12 out of the last 12 quarters.
- Is the third largest emitter of air pollution in the State of California. In 2016, Lehigh released 2600 tons of air pollution, behind two refineries. Lehigh could run a cleaner cement plant, but chooses not to and continues to burn petroleum coke in its cement kiln.[3]
- Emits 17 Toxic Air Contaminants (TACs) above Chronic Trigger Levels and is #1 in Santa Clara County for 13 TACs.
- Is the #2 emitter of Mercury among California’s 8 cement plants. Research has shown that mercury from the cement plant has been detected 20 miles away, demonstrating that the air pollution is a regional problem.
- Has mined materials that are unusually high in contaminants, which contribute to soil, water, and air pollution. According to the U.S. Department of Labor, there are approximately 20 to 30 quarry jobs at the Lehigh quarry; a small number of jobs have caused an unacceptable level of pollution. Additionally, many of these jobs have gone to a non-union out-of-state contractor called Turner Mining; this is the company that built an illegal road in Cupertino's jurisdiction without proper erosion controls in the spring of 2018.
- Parent company, HeidelbergCement Group of Germany has been unable to bring Cupertino’s facility into compliance. This is despite their global experience running 33 cement plants worldwide and being the world’s largest producer of aggregate.
- Has received two Notices of Violation from the County and the Water Boards, filed in June and July 2019, pertaining to an allegedly unstable mountain of mining waste depositing sediment into Permanente Creek.[4]
- Is the most unsafe cement plant in the State of California as measured by proposed labor-safety fines. In 2017, they were levied over $870,000 in labor safety fines. Massive arson and suspicious fires occurred in 1993, 1999, and 2013, siphoning emergency responders from the valley. A 2011 massacre killed four people and injured seven others, including a woman commuting to work who was not affiliated with Lehigh. Given these issues, it is questionable as to whether Lehigh is capable of executing any plan.

The Bay Area does not need local cement. Cement is a fractional component of concrete. Sand is a much larger component of concrete and much of it that is destined for the Bay Area is imported from Canada, so the Bay Area can import cement as well. There are 8 cement plants in California. 16 States in the United States do not have cement plants, including Alaska, Hawaii, and Louisiana. The Bay Area can function without local cement; it functions without lumber mills and steel mills. The Bay Area would have less pollution if the quarry were to close; and even less so if the cement plant were to go elsewhere, away from a large population where fewer people would be affected.

Attached – letters from other Cities and Open Space District
[3] https://ww3.arb.ca.gov/ei/nscpac_fees/nscpac_fees.htm
[4] Click here to get the letters, deed, these violations, and letters about these violations


  1. Write the County Board of Supervisors to reject the 2019 plan: Email the Board of Supervisors, Supervisor Joe Simitian’s aide Kristina Loquist, and cc City Council


    ==> Tell them lack of regulation at these quarries impacts air quality, water quality, and viewsheds.

    ==> Ask them to

    o Request rejection of the Lehigh 2019 Reclamation Plan,

    o Implement the approved 2012 Reclamation Plan,

    o Retain our deeded ridgeline easement, and

    o Exercise appropriate oversight of land-use at the Lehigh Hanson Permanente Quarry and Stevens Creek Quarry.

  2. Attend a Community Meeting on Air Quality pertaining to Lehigh Cement Plant & Quarry and Associated Truck Traffic on Monday, September 16 from 6:30 to 8:30 p.m. Cupertino Community Hall, 10350 Torre Avenue, Cupertino (adjacent to the Cupertino Library). Join the Bay Area Air Quality Management District (BAAQMD) for a presentation and Q&A on measures taken, and in process, to improve air quality and human health related to Lehigh Cement Plant & Quarry and associated truck traffic will be discussed. There are three main sources of pollution, the cement plant, the quarry, and the trucks servicing the quarry.

  3. Come back here and watch for other LAR communications on breaking news.

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