By Mary Hennock

Hong Kong

The campus of the University of Hong Kong is an exercise in doing more with less. Less space, that is. In this notoriously cramped territory, the 100-year-old university has squeezed itself into a steep hillside, ingeniously fitting many buildings into a very tight space.

The main road that sweeps through the campus, for example, twists around ultratight hairpins raised on pilings. It is only way to cram the roadway into the gaps between buildings. Classroom and administrative blocks are hemmed in by residential high-rises stacked up the hillside.

The university is so close to its neighbors, in fact, that "sometimes they call up and say, 'Turn the air-conditioning plants down,'" says John Malpas, the university's pro vice chancellor and vice president for infrastructure.

It's not a promising spot to find space for 3,000 extra students, but that's exactly what Mr. Malpas has done.

This seemingly impossible challenge came about because the territory is switching its undergraduate system from a three-year to a four-year program, beginning in the fall of 2012. Effectively that means all of Hong Kong's universities are going to see enrollments jump by 25 percent.

Somehow, space has to be found to house and teach all of those new students, along with a few hundred extra professors and staff members.

Even in cramped Hong Kong, there is green space in the New Territories, near the border with mainland China. But the University of Hong Kong ruled out this option. As it moves toward interdisciplinary education, its administrators wanted to ensure that humanities students studying climate change and physicists learning Chinese philosophy would have easy access to the entire campus.

Mr. Malpas, a gangling British geologist who is leading the elaborate construction project, says the university had coveted a sliver of space on the west side of its existing campus.

The problem: It was not land but an essential water supply. What's now the construction site for the university's Centennial Campus was originally occupied by three reservoirs, tucked in between the city and a mountain.

His solution: to hollow out the mountain and move two of the reservoirs inside the hill. The third reservoir has been relocated up against the slope, housed in vast sealed tanks.

All this had to be done without disrupting the water supply for more than 120,000 local residents.

Tons of Granite

Work began in April 2007 with a ceremony at which Mr. Malpas, an expert on submarine volcanoes, tapped off the first chunk of rock with his geologist's hammer. Some 33,000 cubic meters of granite had to be removed before the university and its contractors handed the reservoirs back to the city last December.

Today, two years from the planned completion of the project, the 43,000-square-meter site swarms with yellow backhoes, while trucks line up on ramps waiting to carry away the soft, ocher soil.

They are digging out the foundations for buildings that will house the social-sciences faculty, law faculty, and a new universitywide library and interactive study area, known as the Learning Commons.

As part of the development project, the university is creating a connecting spine to unify the two halves of the campus, called University Street or U-Street. It will punch through some existing buildings like the Students' Union (which will require structural re-engineering), opening them up to create new public spaces along the route.

High-speed elevators will rise 90 meters from new subway stops, due in 2014, to the two-tier U-Street, connecting the site vertically as well as horizontally.

The cost of this engineering feat is estimated to be about $77-million U.S., all of it paid by the university.

Public money will cover slightly more that half of the new campus's $385-million price tag, but Mr. Malpas says the university does not want just standard-issue buildings and so is paying for the extras.

Moving the reservoirs cost the university $64 million alone. Any failure would have been very public, as the reservoirs feed luxury homes on Victoria Peak, Hong Kong's iconic tourist destination rising above the harbor-front skyscrapers.

Says Mr. Malpas of his conversations with government officials: "They told us it'd take 10 years. We said 'Sorry guys, we've only got two." In all, 18 government departments have been involved.

Inside the hill, chambers 70 meters high now contain concrete tanks fed with chlorinated seawater used for flushing toilets. Water levels are scanned by automatic sensors. Fresh water is stored in two covered reservoir tanks outdoors against the mountainside.

Landslides and Storms

Landslides are the biggest hazard of any work that disrupts Hong Kong's hillsides. Slope maintenance is a full-time concern: The government keeps a register of all Hong Kong's slopes. Even in rural areas, they're crisscrossed by access steps and concrete drainage gullies.

From the windows of the university's staff cafeteria and bar, the thickly wooded mountain blocks the entire inland view. In a swift geology lesson, Mr. Malpas explains that though Hong Kong is mostly hard granite, the tropical monsoon weathers the rock to several meters deep, making it "very friable." To avoid damaging hillsides or vegetation, contractors excavated without explosives.

The project has largely gone as planned. But on June 7, 2008, severe storms hit Hong Kong, triggering dozens of landslides. A 100-meter-high forked gash opened in the hillside above the Centennial Campus site that day.

Woken early on a Saturday, Mr. Malpas couldn't even get onto the campus from his home across the road.

"All the soil was washed into the university," he recalls. Parts of the slope "slid one kilometer down to the harbor-front."

An anxious call to the government department in charge of slope control yielded bad news—with 162 severe landslides, the university was going to have to fix the damage itself rather than rely on overwhelmed government resources if it wanted to stick to its schedule.

When the Centennial Campus is completed, it will include an ecologically exemplary "green lung," with 100 newly planted trees growing above the fresh-water reservoirs in a gigantic soil tray. Where there's now a concrete roof with stubs of protruding steel, a raised platform will hold a 4,000-square-meter water-and-sculpture garden.

Having moved a mountain, the University of Hong Kong plans to walk on water.