But the USGS Earth Resources Observation and Science (EROS) Center that collects Landsat imagery has monitored the environmental impact of its energy consumption and waste production since its design stage more than 50 years ago.

And that has required more effort than you might expect, going beyond simply maintaining a large building northeast of Sioux Falls, South Dakota, with hundreds of employees. EROS has succeeded time and again at minimizing its footprint—including careful handling of photo-processing chemicals, employee-driven efforts to make the commute affordable and sustainable, and reuse of the heat produced by today’s high-performance computers.

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Protecting the Water

In the years before digital imagery, distribution from the Landsat archive required processing film into physical photographs so they could be analyzed by the human eye. Producing hundreds of prints a day required an astounding amount of water, as much as 20,000 gallons!

To accommodate this volume, the iconic 250,000-gallon EROS water tower, which still provides water for EROS and the surrounding farms, was installed. But dealing with the wastewater required more careful and innovative planning.

“We did a lot of things that Eastman Kodak said couldn't be done,” said Brent Nelson, information and management services operations work manager and contractor at EROS, referring in particular to photo chemicals. The idea was, first of all, to regenerate the silver-based chemicals as much as possible, with some photo fixers being reused 50 times—representing a significant cost savings for taxpayers.

The next step was reclaiming the silver before sending the wastewater through the treatment system. The electrolytic silver recovery unit collected the metal over time, then the heavy silver-laden cathodes were removed, “set in a safe to be dried out, and after they had so many of the cathodes they would—with security—go through and bust the silver off of that, weigh it and put it up for auction,” said Nelson. In April 1975, the Sioux Falls Argus Leader reported that $4,000 was returned to the U.S. Geological Survey each month from the 5-10 pounds of silver recovered. Later, an in-situ system similar to home water softeners collected the silver in easier-to-handle bead form.

After the silver was removed from the fixer chemicals and developer fluids were ozonated in a separate process, the wastewater was sent through a series of five pools, some 20 feet deep, where the water was allowed to settle and tested regularly to ensure it met Environmental Protection Agency guidelines.

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Running Hot and Cold

The water used to process color prints had to be hot. In the energy-conscious 1970s, EROS innovated again, getting a $646,600 grant from the Sioux Falls Development Foundation in 1978 for a solar energy system to heat the water.

Estimates predicted that the system would contribute 58.5% of the energy required to preheat the water and would have an economic payback in 10 years. A federal grant of $500,000 also helped fund the 10,000-square-foot installation in 1980. The solar water heating system was one of the largest in the United States at that time.

Hot South Dakota summers, meanwhile, created a dilemma in acquiring the cold water necessary for black and white image processing, Nelson said. On 100-degree days, the water in the tower was too hot to cool the B&W developers. The simple solution? Not overfilling the tower. The constant influx of fresh water kept the supply at the right temperature for EROS’ needs.

Softball-sized hail destroyed the solar panels on a July Sunday in 1997—along with a brand-new satellite antenna, the windows in the recently added atrium and every car in the EROS parking lot. By this time, prints were slowly being replaced by digital imagery, so EROS leadership decided not to rebuild the solar water heating system.

Vanpooling to EROS

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While EROS trimmed costs at the center, employees trimmed costs at the gas pump.

“We were staring at potential gas rationing,” said Tim Smith, information management services archive task lead and contractor at EROS. “Fuel costs were rising, and people didn't have the in-pocket capabilities to take that ride by themselves.”

Through a grant from South Eastern Council of Governments (a group of municipalities in South Dakota), the employee association purchased one van in 1979, then quickly added three more. Each carried up to 14 people, and the idea caught fire. At its height, the vanpool boasted seven vans carrying 102 people to EROS, with routes reaching nearby Brandon, Dell Rapids and Trent in addition to the five vans that serviced Sioux Falls. The rideshare program even won a federal award in 1984 for innovation.

Smith estimated that in the first 20 years, the vanpool served 34,000,000 passenger miles and saved 450,000 gallons of gas. Cost per passenger was \$36 per month at the beginning; by 2020, with only 20 passengers remaining, costs were still only \$85 per person. The COVID-19 epidemic’s government-wide closure—with many people opting to work at least part of the week from home even after the center reopened in 2022—sealed the fate of the already dwindling program, and the three remaining vans were sold.

Cool Computers

From the very beginning, EROS depended on computers for a wide variety of purposes, from processing orders to interpreting imagery to scientific experiments. The first computer in 1971, an IBM 360-30 with only 64 kilobytes of memory, was replaced by a Burroughs mainframe computer in 1976. The Burroughs, at the time one of the biggest computers in the Midwest, took up two-thirds of the computer room and produced a good deal of heat.

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In 1980, in response to a government-wide mandate to reduce energy costs, EROS maintenance contractor Vesco installed a system to capture heat from the computer to keep the entire center warm. It worked so well that it exceeded the mandated 15% reduction, cutting energy consumption by 37%.

In the modern era, high-performance computers at EROS such as the just-installed Hovenweep take up far less space in the computer room but perform at unbelievable speeds. Hovenweep’s performance, when fully installed, is estimated at 660 teraflops—a teraflop corresponds to 1 trillion floating operations per second. Like its computing companions already operational at EROS, Tallgrass and Denali, Hovenweep will require specialized chillers called Computer Room Air Conditioning (CRAC) units.

“That’s basically a big cooling coil with a whole lot of big fans in it,” said EROS facility engineer Jesse Boyer. “When you walk into the computer room, that’s what you hear.” Clear curtains surrounding each computer help reduce the space that needs to be cooled, and heat from the computers is funneled into a hallway where it can more easily be captured, making it easier to be used to keep the facility warm in winter. In summer, it’s simply vented to the outside.

Every time a new CRAC unit is installed, Boyer said, there’s an improvement in efficiency. Those efficiency savings are important because there’s no getting around the fact that the overwhelming majority of energy used at EROS is consumed by the computers needed to perform the center’s core mission.

People Power

By comparison, smaller efforts such as converting all light fixtures to LEDs and using motion sensors to turn lights on and off account for only a tiny fraction of energy conservation. Still, EROS emphasizes all possible ways to reduce both costs and usage, not only in respect to energy but with other environmentally sound measures.

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“We look for energy savings wherever we can, including low-flow fixtures in the bathrooms,” said Tracy Michel, USGS safety and occupational health specialist at EROS. “We recycle office waste as much as possible to reduce landfill waste.” Part of that is because EROS is mandated to find savings, but it’s also an ethic that pervades the center. For example, water coolers throughout the building have convenient water bottle filling stations. This doesn’t necessarily save the government any money, but it does help prevent plastic waste.

Michel has a unique perspective on EROS’ conservation efforts. She was previously a consultant who verified whether the ponds that treated wastewater from photo processing did their job, testing the sludge in the early 2000s before the photo lab closed in 2004. Michel’s verdict? “Tests were well within current EPA limits,” she said.

The ponds are still tested because they function as a regular wastewater system for the center. Now, Michel helps ensure that any cleaners, solvents or other chemicals don’t end up in the ponds—maintaining the tradition of conservation that started 50 years ago.