The research team was racking their brains to come up with the first version of the walker repellent, while Gwendolyn had already given Lilly several psychological therapy sessions.
But lately, Calista had no time to concern herself with any of that. She was planning something else.
At the Rock Fortress command center, Calista, Leah, Rickson, Elena, and Benjamin gathered around a table covered by a map of the Great Smoky Mountains.
There was only one issue on the agenda: how to make sure the people at the base would not spend this winter struggling through the bitter cold like they had last year.
"Hydropower works fine during the wet season, but according to our records, from mid-January through the end of February, Black Bear Creek drops to about thirty percent of its summer flow. Ice also interferes with the water intake."
Elena pointed to the river marked on the map, her brow furrowed. "If we rely on burning wood and the limited fuel reserves in storage like we did last year, we'll have the same problems. Too much smoke, polluted indoor air, and a rate of logging that the forest simply can't sustain.
"And now that the greenhouses at Blackberry Ranch have been expanded, their heating needs will be even greater this winter."
Rickson folded his arms. "We've collected more solar panels, but winter means fewer hours of sunlight and weaker intensity. They can only supplement the system. We need a more stable primary heat source, something that isn't so dependent on the weather."
Benjamin was also a faculty member at UTK, an electrical engineering lecturer who was equally knowledgeable about renewable energy systems. Ever since arriving at Rock Fortress, he had been responsible for most of the electrical work.
His responsibilities had gradually expanded from Rock Fortress and Blackberry Ranch all the way to the Knoxville Industrial Park, but this was the first time he had attended a high-level meeting like this. Until now, he had remained silent and listened.
Benjamin glanced around the table before finally speaking, still somewhat nervous. He tapped an area outlined with dashed lines inside Great Smoky Mountains National Park.
"Maybe... instead of looking to the sky or the water, we should look beneath our feet."
Everyone turned toward him.
Benjamin explained, "The Great Smoky Mountains were formed by ancient mountain-building activity. The region still has areas with geothermal anomalies.
"The clearest evidence is the hot springs scattered throughout the mountains. Before the disaster, some of them were tourist attractions."
He pointed to a faint mark on the map. "Here. I remember there being a hot spring around this area, roughly twelve to fifteen kilometers in a straight line from the ridge east of us.
"If the spring has enough flow and a high enough temperature, we could build a pipeline system and bring the hot water down the mountain. Or at the very least, establish a transfer station partway down the slope and make use of the heat there."
"Geothermal?" Elena's eyes lit up, though she quickly frowned again. "It's not close, and those mountain roads will be even harder to use in winter. We don't have drilling equipment, but if the natural spring itself is usable..."
"It doesn't have to mean piping the water itself all the way down," Benjamin continued. "A heat-exchange system would actually be more practical.
"We could transfer the hot spring's heat into a medium circulating through a closed pipeline and bring that heat down to the main buildings at Rock Fortress and Blackberry Ranch, as well as the core greenhouses.
"That would avoid the heat loss and freezing risk that come with transporting large amounts of hot water over a long distance. Technically, it would also be simpler. We already have enough metal piping and pumps at the base to put together a basic system."
Calista quickly weighed the idea.
It was spring now, and they had plenty of manpower. If they moved quickly, they should be able to complete the survey before winter and lay at least a few sections of pipeline. She had no idea how much they could finish, but surely they could get at least one line working.
The potential payoff was enormous: a sustainable, stable, clean source of base-load heat.
Calista quickly made her decision. "We already discussed this possibility last year. This winter, we have to get our heating situation under control.
"Right now, the base's non-renewable options are thermal power and fuel. As for renewables, hydro and solar are too unstable in winter to rely on.
"Given the geography of the Great Smoky Mountains, geothermal is probably the most realistic option available to us right now."
Leah nodded. "Then the next step is a survey. We need to confirm the spring's exact location, flow rate, temperature, surrounding terrain, and whether the area is safe."
"Exactly," Calista said. "Elena, Benjamin, you'll handle the engineering assessment and route planning and accompany the team as consultants. As for security..."
She paused.
"This mission shouldn't be particularly dangerous. We've cleared most of the surrounding woods already. The main problems will be the terrain and a few scattered walkers. Let's give the newer people a chance to prove themselves."
Her meaning was obvious.
Leah understood immediately. "Ever since we formed the drone team, Bossie has been overseeing drone operations.
"During the recent Block D operation, the reconnaissance workload was heavy. Allen Miller and Billy were the only ones operating drones, so they were short-handed. Bossie asked me to transfer Jenson over as well.
"And Anderson was also part of Hank's squad, which suddenly left Hank short three people.
"So I assigned the newcomers Maggie, Glenn, and Carol to his squad. We can send Hank's team this time."
Calista nodded. "That works. This is strictly a reconnaissance and engineering feasibility assessment. We don't need extra labor.
"Confirm whether the hot spring is usable, map a detailed route, draft the pipeline layout, estimate construction difficulty and labor requirements. If we come back with that data, the mission is a success."
"Understood!" everyone replied.
...
Three days later, a small team left Rock Fortress and headed east into the mountains.
Hank's squad kept Elena, Benjamin, and Aleksei protected in the center of the formation.
Aleksei was tall and strong, carrying a pack stuffed with specialized tools and sample bags. On this trip, he was serving as Elena and Benjamin's assistant.
Hank and the others were fairly familiar with the first stretch of the route. The Defense Force had already cleared the area, and they had scouted it several times before.
But as they climbed higher, the forest grew denser, the terrain became rougher, and traces of human activity nearly disappeared.
Slippery stones and tangled roots hid beneath layers of rotting leaves. One careless step could send someone sprawling, so the team's pace gradually slowed.
Hank and two team members moved about twenty meters ahead, alternating positions as they advanced.
Glenn and Maggie moved parallel to the main group about ten meters out on either side, watching the gaps between the trees and the dense undergrowth.
Carol and two other team members covered the rear.
Elena and Benjamin were both somewhere in their thirties or forties, while the rest of the team were younger adults in their prime. They could keep a decent pace, but the survey work required constant observation.
Elena stopped from time to time to inspect exposed rock with a magnifying glass, pick up a stone and weigh it in her hand, or crouch down to examine the types of moss and the moisture in the soil.
"The rock here is transitioning from sandstone to shale," she said quickly to Aleksei beside her.
Aleksei immediately marked the location on his handheld device, then added for Benjamin, "The change in the rock layer suggests water may be starting to collect here."
Benjamin nodded and marked the geological point on the map while estimating the slope, silently calculating the possible angles for future pipeline installation and where support points might be needed.