The Permanente Quarry is a limestone quarry in Cupertino, California. The quarry is a limestone and aggregate mining operation and cement plant, owned by Lehigh Southwest Cement, a subsidiary of HeidelbergCement. Located in the foothills above Cupertino on the northeast slopes of Black Mountain, the quarry runs east-west parallel to the upper watershed of Permanente Creek to the south and to Permanente Ridge and Rancho San Antonio Open Space Preserve to the north.
The limestone rock found in the Permanente Creek valley and on the summit of Black Mountain is relatively unique in the Bay Area. Microfossils in the limestone deposits suggest that the mountain originated as a seamount at 22 degrees north in the tropical Pacific about 100 million years ago and was transported to Los Altos by the Pacific Plate.[2][3][4] These rocks occur as jagged gray boulders and outcrops just southwest of the radio towers on the summit of Black Mountain, as well as in the Permanente Quarry. Calera is the Spanish word for 'limekiln', reflecting how limestone was burned historically to produce lime, an key ingredient for mortar
The quarry was originally founded by Henry J. Kaiser as the Kaiser Permanente Cement Plant in 1939, taking the name of the business from the Permanente Creek in whose valley it lies. Kaiser intended to use the quarry to provide the majority of the cement used in the construction of the Shasta Dam, supplying the 6 million barrels (950,000 m3) of cement . The cement plant is the sole reason for the lone railroad line that runs through the city.
On October 5, 2011, the Lehigh Southwest Cement plant was the site of a shooting in which a disgruntled employee shot and killed three people, and wounded seven
Mercury Emissions
The cement plant at the quarry has been fueled by petroleum coke since 2007, the latter (along with the limestone itself) is a major source of mercury emissions. The cement plant is responsible for 29% of total Bay Area airborne mercury emissions and was shown to impact a rural site, Calero Reservoir, 20 miles (32 km) away.[8] Mercury, a neurotoxin and pollutant which is concentrated in the aquatic food web, was found to be 5.8 to 6.7 times higher in precipitation near the cement plant than at a control location 2.0 miles (3.2 km) away.[9] A 2011 study showed a significant geographic association between the occurrence of autism in local school districts and higher levels of ambient mercury generated by coal-fired power plants in Bexar County, Texas and the Permanente Quarry cement plant in Santa Clara County, California
A view of Lehigh Southwest Cement's Permanente Quarry looking north from the summit of Black Mountainacross the quarry and over Silicon Valley
Selenium Discharges into Permanente Creek
Groundwater fills the current quarry and is pumped into Permanente Creek. Selenium pollution in the creek downstream from the quarry ranged from 13 to 81 micrograms/liter (μg/L). A North Quarry water sample in January 2010 had a dissolved selenium concentration of 82 μg/L, indicating that the quarry is the source of the selenium pollution. Selenium is bioaccumulated in the aquatic food web.[11] Safety standards for selenium concentrations in fresh water are 5 μg/L under the California Toxics Rule (same as the National Toxics Rule set by the U.S. Environmental Protection Agency (USEPA) in 2000 and 2012.[12]
[edit]Sediment Discharges into Permanente Creek
Anthropomorphic activities related to quarry operations and the cement plant have resulted in sediment discharges into Permanente Creek that are 3.5 times what would be expected under normal conditions.[13] Sediment loads in the upper Permanente Creek mainstem are 15 times those in the West Fork Permanente Creek, which drains mostly parkland. These sediment loads could threaten the resident rainbow trout (Oncorhynchus mykiss) population in the creek.
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