Water runs downhill. Oahu’s valleys have been scoured out by water rushing downhill over the eons. Manoa Stream, for example, went this way and that way as it dug out the valley, that is, until people arrived and made Manoa Stream go that way and this way because it better suited the street plan.

As long as the stream bed was kept clear, it worked pretty well. During the evening of Oct. 30, 2004, however, a torrential downpour deep in the valley caused Manoa Stream to jump its banks. Tons of water surged down the faint shadow of the old stream bed, a runaway locomotive of incredible force, a berserk rhino of filthy water, hurtling mud and tumbling debris, blasting into and through everything in its path.

At roughly 7:55 p.m. the wall of water slammed into Hamilton Library on the University of Hawaii campus.

At that moment, Hamilton building manager Steve Pickering was out of the rain, enjoying a movie at the Varsity Theatre. When he got home a few minutes after 10 p.m., Pickering got a phone call. "There may be some flood damage at the library and the power was out."

As he descended a stairwell, Pickering shined a flashlight about, imagining a couple of inches of water on the ground floor.

The flashlight revealed a scene of incredible damage, as if a bomb had gone off. Walls were blown out, furniture was shredded and slimy mud dipped everything into a greasy fondue, including the library’s invaluable collection of documents and maps. Pickering, a tall, quiet sort of guy, has trouble today formulating words that illuminate the magnitude of the disaster at the time. He knew there would be no sleep for several days.

Six years later, Hamilton’s ravaged ground floor is again open for scholarship. If you’re on campus this afternoon, there’s an open house to show off the changes.

Pickering and Alan Grosenheider, assistant to the university librarian, provided the Star-Advertiser a look at the rebuilt Government Documents and Maps Collections and Collections Services, the map room’s geographic information system (GIS) lab and the Department of Information and Computer Science’s Library and Information Sciences areas.

This last was the scene of some terror that night. A library sciences class was trapped in a room as the waters rose — "Fire doors are designed to swing out to escape, but you can’t do that with six feet of water on the other side," said Pickering — and students resorted to smashing a window to escape.

Hamilton is the largest — well, the only — academic research library in the Central Pacific, hosting more than 2,800 students and researchers on an average day. As a structure, it’s buffed up to handle the great weight of books and documents. What happened in the great flood was a fluke, but the building’s design worked against it.

As built, there was a kind of "moat" constructed around the foundation to allow light to enter ground-floor windows. Several feet deep and encircling half the structure, the moat was closed off at the ends. When the diverted Manoa Stream hit it, the moat filled up and exerted tremendous pressure on the windows. When they shattered, tons of water jetted through the ground floor instead of passing around the library.

The moat is filled today with an earthen berm and rocks, "a flood mitigation construction, should it ever hit again from that side," said Grosenheider.

The ground floor of Hamilton was expanded, mostly by excavating beneath the substantial moat structure, adding nearly 8,000 square feet. Departments were redesigned, based on input from the employees, creating a better work flow. The cost is in the neighborhood of $37 million, with $25 million coming from the state’s insurance policy on the structure. Much of the rest comes from the Federal Emergency Management Agency.

"Thank goodness for FEMA," said Pickering, citing the one silver lining in that Manoa storm cloud. "We were able to create a better ground floor."

Like the watertight containers built on a ship, the ground floor of Hamilton now features departments divided like cells by stout concrete walls. Emergency exits and accesses have been added as well.

"When the water came though, it just blew right through the gypsum board walls that were here before. They turned into Kleenex," said Pickering. Where it entered, on the moat side, the water reached as high as the ceiling, even overflowing up to the first floor. By the time it exited the building on the other side, it had dropped a couple of feet. Some top rows of books were spared; most tumbled when the shelving collapsed. "Some offices were spared completely; it was the oddest thing," said Grosenheider.

"Another office — there was no trace of it. It was completely gone," said Pickering. "The water had pretty much left the building within a half-hour."

Hardest hit were the government documents, photographs and maps collections. Grosenheider estimates they were "90 percent obliterated."

More difficult to estimate were the years of scholarly research wiped out. Some hard drives were rescued from sunken computers and some data saved. But for some of the researchers, their life’s effort had been washed away. "The intellectual-property loss was staggering," said Grosenheider.

Restoration experts know you have maybe three days after a flood before mold sets in, ruining items completely. The government documents could be largely replaced from other libraries. The immediate struggle was to bring electricity back to the structure. Generators and external air conditioners mitigated the power loss, while a triage team of archivists and geography professors peeled through sodden masses of wet maps and soaking aerial mapping photographs. "Five or six (ocean) container-sized freezers were located and brought to campus. If you freeze these documents right away, they can be saved," said Grosenheider.

But thousands could not be saved. Some rare maps were found blocks away, turned into papier-mache and hanging on bushes. Some library materials were actually found in the student parking structure.

Climate control was a problem. While the building was wet, the bottom floor turned into a chilly "swamp cooler," while the top floors reached 100 degrees and higher. "We were without air conditioners for four months because the first things hit in the flood were the chillers," said Pickering. The rebuilt library now has its climate-control machinery in an above-ground addition.

The work of cleanup was grinding and seemingly endless. "In the beginning, volunteers brought sandwiches and stuff while we worked in the dark with headlamps," said Pickering. "We brought in a recovery/salvage team from the mainland to handle the debris. Everyone had their little moment of tears."

Kim Nakano, head of acquisitions, said coming back into the library "is part of the healing, getting over this tragic and overwhelming experience." Personnel in her department and others were scattered, anywhere they could set up a desk, for the past six years. Mike Chopey, head of cataloging, described the "shock and horror as the whole library staff" crawled into the wreckage to salvage what they could.

In the government documents section, librarian Gwen Sinclair described how some documents were kept in rented rooms at Dole Cannery. "We took turns driving a daily shuttle to retrieve documents," she laughed (but not too hard). "Invariably, somebody would need something really rare on a Friday afternoon."

According to Sinclair, about 80 percent of the maps and documents have been replaced, due to the generosity of more than 200 libraries across the nation.

"We heard from everybody," said G. Salim Mohammed, mapping and GIS librarian. "The mapping community in the U.S. is pretty tight."

Another stroke of luck: The university has a paper restoration and conservation lab right next door, manned by former Bishop Museum professionals.

"Thank you, FEMA!" exclaimed Lynn Davis, lab director. "We’re able to save thousands of materials thanks to modern equipment that government funds. There is national interest in cultural materials and conservation preparedness because of this flood, because of Hurricane Katrina."

The work goes on. There still a shipping container of frozen documents and maps parked on campus. This semester, the scattered Hamilton librarians are returning to their resurrected departments, due primarily to:

"FEMA money," said Grosenheider.

"Good help from others," said Sinclair.

"And lots of hard, hard work," said Pickering.