Sam Camp seems to know every rock — every angle of every rock — on the 5 acres of land. He walks with sure but careful steps, pausing to point out the faintest outlines of ancient drawings in the huge stones.

“I call this one the 11 o’clock petroglyph,” Camp says, pointing to a rock face that bears the suggestion of a line. When the sun is at the right angle, the image reveals itself. Camp moves to another rock. At this one, if you hold your head in a certain angle, the outlines of a male figure suddenly become clear.

For three years, Camp has devoted five hours a day, six days a week to the Hawea Heiau Complex, clearing away years of overgrowth and trying to undo damage from developers’ bulldozers on the culturally significant site along one of the busiest streets in Hawaii Kai.

The property, which contains a portion of Keawaawa wetland, a spring-fed well, an ancient coconut grove and agricultural terraces, was purchased by the nonprofit community group Livable Hawaii Kai Hui in 2014 to keep the land as a cultural heritage preserve in perpetuity. The hui had been caring for the land, which is between the Oahu Club and the new Hale Ka Lae apartment building, since 2009.

Hawea is a mile from Camp’s house. Last year, he put only 3,000 miles on his truck, and most of that was just going between Hawea and home.

“I leave my cellphone in the car. I don’t want to be distracted when I’m here. I’m happy to be in this place and in my mind.”

Camp grew up on Oahu, graduated from Roosevelt in 1960 and spent 11 years studying agricultural economics at the University of Hawaii. He never finished his dissertation for his Ph.D., though he started on seven different topics. “Every time I got a research grant, I’d change my dissertation to fit,” he said. He spent his career with the state Department of Agriculture, retiring in 2004.

After retiring, he volunteered at Kapiolani Community College to work on the campus cactus and succulent garden. He worked there for eight years.

And then one day, he passed by Hawea and it caught his attention.

“I saw a sign out here about a workday coming up,” he said.

In April 2013, Camp attended his first community workday at Hawea. It was tough stuff. So many of the invasive species — bougainvillea, kiawe, night-blooming cereus — are full of thorns. Camp shrugged it off. “I had eight years working with cactus,” he said.

He came back for other Saturday community workdays, but wanted to do more. “This place has so much vegetation, if I come only once a week or one time a month, the work will never get done,” he said. So he received permission from the hui to come out on his own time.

Camp started a journal about things he would see and find. He included photos and emailed his journal entries to members of the hui and anyone who might be interested. Included on his distribution list was retired KCC math teacher Jim Metz, who worked with Camp at the cactus garden. Metz travels with Teachers Across Borders, going to far-flung countries to train teachers. He was in Liberia when he got Camp’s message, but even that far away, he felt a calling.

When Metz returned to Hawaii, he joined Camp at a Hawea workday. He’s been faithful ever since. Though he travels the world with Teachers Across Borders, he says, “When I’m gone, I miss this place.”

The work they put in over long, sunlit hours is impressive. Camp and Metz estimate they’ve collected 8,000 errant tennis balls from the club next door. They’ve come to know every alae ula native bird that nests in the wetlands. They’ve worked alongside inmates from the women’s correctional facility hacking away a hillside of thorny invasive plants. “Those women work so hard,” Camp said.

“Really hard,” Metz agreed.

The two men talk like they’re so happy here, but perhaps happy isn’t the right word. What they feel is that elusive thing that people search for — a peaceful sense of purpose, the joy of learning and the blessing of meaningful work.

“As we started clearing, first we were saving what the archaeologists noticed. And then we started finding stuff the archaeologists didn’t know about,” Camp said. “Nature protected this place. Now we’re uncovering it, so we have to protect it.”

For a while, Camp was dividing his efforts between KCC and Hawea, but in September 2013, he decided to devote all his time to Hawea.

“I was really starting to feel aloha for this place.”