The Aromas quarry takes a big step toward energy independence.
At the Graniterock quarry in Aromas, a conveyor belt more than a mile-and-a-half long takes the “overburden”—rock not suitable for construction use—from the quarry, then across hills and valleys, until it reaches Big Bill, a massive brontosaurus-shaped machine on caterpillar tracks, that spits it out over the edge of a plateau.
Graniterock was founded 121 years ago and operates the A. R. Wilson quarry. At around 1,000 acres and dug to a depth of 120 feet below sea level, it is the largest crushed rock quarry west of the Mississippi River. Currently, Big Bill and the conveyor belt, as well as most of the machines on the site, are being powered by two 750-megawatt PG&E substations.
Usually, a herd of grazing cows would be about the only thing keeping Big Bill company. But for the last three months, engineers have displaced the cows as they work to install solar panels as part of Graniterock’s $15 million investment in green technology.
“We have found that we can soundly, and safely and within permit, put up a 15,000-panel solar array on top of the overburden,” said Keith Severson, director of marketing and community involvement at Graniterock. “It will generate 5.3-megawatts of electricity, which will provide energy for 60% of this quarry and take that much off the grid, benefiting the community of Aromas and all of San Benito County.”
The panels will generate roughly the same amount of power used by approximately 1,350 homes, according to the Solar Energies Industries Association.
The new solar project will be the second one on the site. In 2018, Graniterock built a 1-megawatt solar farm at the quarry entrance. Consisting of 3,000 solar panels, it generates 15% of the quarry’s power. It was the beginning of the company working toward better energy efficiency.
“We started out with this little solar farm,” Severson said. “We saw that we could do this kind of thing successfully, so we did a retrofit on the corporate office in Watsonville, tinted the windows, changed the heating and air conditioning, and put a solar array on the roof. That building was not designed green but is now close to net-zero. I think the green evolution of corporations will be similar to what we are doing here.”
The project began three years ago when members of the newly formed Aromas Progressive Action League (APAL) met with Graniterock to discuss ways of making the city and surrounding area a net-zero community.
“Graniterock always comes to our Aromas Day celebration,” said APAL member Leslie Austin, “and that gave us a chance to talk with their representatives. And it turned out that they were primed for the conversation and had already been working on plans for solar power. Our goal was to help them connect with the people and companies they would need to pull off this huge project.”
The 20-acre plateau that Big Bill stands on, the location for the new solar farm, was created by filling a valley with waste from the quarry: overburden and crushed granite particles. “Many years ago, there were a group of Aromas residents who really fought back against the overburden filling the valley,” Austin said. “But now it is the perfect place for this kind of project. There are no species to protect, there are no animals to protect. It is just dead ground, but it is the perfect compacted ground for something like solar panels.”
Severson agrees. “That is the beauty of this plan,” he said. “There was really no negative environmental impact. This was a large plot of reclaimed land that was only used for cattle grazing and we moved them to a nice new green pasture.”
Besides relocating the cows, the only work done to prepare the area for the solar panels was grading the overburden.
“We didn’t have to move a lot of dirt,” Severson said. “We just had to get the right slope so the panels will face the sun most of the time and to let water drain off. The weather was kind to us so we got it done on schedule, by the end of March. We will be putting in a new transmission line that will be closer to where the power is needed.”
The project is set to pay for itself in 15 years. According to Severson, the panels should last for 30 years and can be swapped out as they age or could be replaced entirely by whatever new technology is available at that time.
“If this goes as planned, we look forward to expanding in the future,” Severson said. “There is an area beneath the plateau which is just native grasses. We would love to build in that area, too, so we can become 100% off the grid—and perhaps be able to put something back into the grid. And the future might also include some battery capability so we can capture some of the power.”
The project is scheduled to be completed in the first quarter of 2022.
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