Chicago redefined the urban nightmare last Monday when a section of abandoned tunnel ruptured and the Chicago River poured into downtown, wreaking hundreds of millions of dollars in damage.
Could such a disaster occur in Baltimore, with its own century-old underground rail tunnels and aging system of water and sewer lines?
Civil engineers contemplating such doomsday scenarios answer simply: No, the Chicago River doesn't come within 500 miles of here.
In fact, the exact circumstances facing the Windy City are unique and unlikely to be duplicated elsewhere.
But that doesn't mean Baltimore is in the clear. Experts say that below the surface of city streets there are potential crises lying in wait.
The culprit: infrastructure neglect. For too long, Baltimore, like most other communities across the country, has allowed its infrastructure -- its networks of highways, bridges, underground pipes and sewage plants -- to deteriorate.
"The older and the bigger the city, the more problems that you'll have," warned Max Whitman, president of the Chicago-based American Public Works Association. "Decaying underground facilities pose one of our greatest problems."
Mr. Whitman and others believe the country has deferred routine maintenance for too many years. Government investment in public works has declined from 20 percent of total expenditures in 1950 to 7 percent by 1984, according to the association.
As a whole, the United States spent about 0.3 percent of its gross national product on infrastructure between 1980 and 1989. Canada spent six times as much, Germany 12 times that amount and Japan invested 5.7 percent of its GNP, or 19 times what the United States did.
Baltimore, like other communities -- particularly in the older Northeast -- has seen its share of water and sewer spillages, power outages, leaking underground gas tanks and other small-scale catastrophes. There are water lines that are 80 or 90 years old, and engineers can only marvel that they've lasted as long as they have.
"Water doesn't run uphill"
But the primary reason the city is unlikely to experience Chicago-size flooding is a simple matter of physics: Water runs downhill. The city is built above sea level, and excess water would drain toward the harbor.
"Water doesn't run uphill yet," said George G. Balog, Baltimore's public works director.
Beneath Baltimore is a veritable web of structures that make the city work: pipelines, steam lines, utility conduits and tunnels.
The newest of the tunnels belongs to Metro, which operates three miles of track underground and is tunneling 1.5 miles more with an extension to Johns Hopkins Hospital.
Perhaps the most significant Metro-related problem developed in November 1990 when workers digging underneath Orleans Street caused a water main to break. The gushing water swept away tons of soil, and the resulting cave-in severed utility lines and left behind a 25-foot-wide, 12-foot-deep crater.
But the incident was isolated. Finished tunnels have posed no such problems, and the normal water seepage can be easily accommodated by the Metro's system of sump pumps, said Peter J. Schmidt, who oversees Metro construction for the Mass Transit Administration.
"It's extremely unlikely that we could get flooded, and even if we did, we couldn't affect anyone else," Mr. Schmidt said.
The oldest tunnels
The oldest of Baltimore's tunnels serve railroads: the mile-long Baltimore and Potomac Railroad tunnel, which runs into Penn Station from the west; the half-mile-long Union Tunnel, which runs from Penn Station to the east; and the Howard Street Tunnel, which carries CSX trains underground from Mount Royal Station south to Camden Station.
Officials with Amtrak and CSX Transportation Inc. insist that the tunnels are in good shape despite their age, that they undergo regular inspections and that they pose no danger to the public.
The Baltimore and Potomac, for instance, dates to 1873 but is constructed of limestone walls 4 to 6 feet thick and is an average of 25 feet above sea level.
"Even if there was a rupture of a city water main, the Howard Street tunnel is so large and the grade is straight down toward the Patapsco [River], it's not possible for it to flood," said Lynn Johnson, a CSX spokesman.
Concern for Roland Dam
One of the only city-owned projects that could approach the scale of Chicago's disaster, if it broke, is Lake Roland Dam in Robert E. Lee Park, just over the northern city line in Baltimore County.
The dam, built in 1862, for years has been showing signs of age, and its weakness has concerned city and state officials, especially during heavy storms.
If it collapsed, it would send a wall of water roaring down the Jones Falls Valley, with 2,000 residents in its immediate path.
A state dam official recently termed the structure "a major disaster waiting to happen."
"The dam has to be fortified," Mr. Balog said, noting that the first phase of repairs is already under way.
The Maryland General Assembly recently approved $2.1 million toward the dam's $7 million repair cost.
Aging mains and drains
At less immediate peril are miles of pipes, drains, concrete boxes and culverts that move water, storm water and sewage beneath the city's streets. They are aging structures that average 50 years old, but some are nearly 100 years old, Mr. Balog said.
Some of the water pipes -- as large as 12 feet in diameter -- run huge distances, linking reservoirs in Baltimore County, and even the Susquehanna River, to filtration plants in the city, he said.
From there, water is dispersed throughout the city, under the streets, in a series of pipe systems that bring water to your faucet.
Sewage moves in the opposite way: from small pipes to huge pipes -- such as the 54-inch Gwynns Falls sewage transmission main -- that can channel waste either to the Patapsco or Back River wastewater treatment plants, he said.
Mr. Balog said the city is responsible for 3,000 miles of water mains, in Baltimore, Baltimore County and some parts of Anne Arundel County; 2,000 miles of sanitary sewers in the city; 1,000 miles of storm drains in the city; 40 miles of open channels (ranging from small streams to the Jones Falls and Gwynns Falls) in the city; and 16,000 manholes and 33,000 inlets, all in the city.
Some of the oldest conduits, and some of the largest, are the pipes and concrete boxes that carry water from the city's reservoirs such as Loch Raven, Liberty and Prettyboy to filtration plants at Ashburton and Montebello, Mr. Balog said.
He said a 108-inch water main that runs more than 30 miles from the Susquehanna to the Montebello filtration plant dates to 1915, when the plant first opened.
Other mains that feed Montebello date to 1928, when a second plant opened there.
The large conduits from Loch Raven Reservoir date to 1912, when the dam was completed at the Gunpowder River.
The Department of Public Works monitors these conduits and others in the city through inspections and computer modeling of age and construction of the structure.
From that, engineers are able to set priorities for the coming year's construction and maintenance budgets, the director said.
City officials insist that they have been aggressive in their maintenance efforts, routinely replacing or relining suspect water and sewer lines.
In a recent dispute over water-sewer rates with Baltimore County, the city won an arbitration and was awarded $10 million. Mr. Balog has pledged to put that money -- once it is collected -- into the city's infrastructure.
System depends on gravity
Mr. Balog also noted that the water in the lines from the reservoirs -- among the largest conduits the city oversees -- is not under pressure, because that system depends generally on gravity for the water to get from Point A to Point B.
"They're almost like a tunnel . . . and the likelihood of their TTC bursting is almost non-existent," Mr. Balog said.
In addition, there is no tunnel system in Baltimore remotely similar to the labyrinth of tunnels beneath Chicago, he said.
A more realistic threat might come from a hurricane or other severe storm in which the amount of water rushing through storm drains that empty into the harbor might back up and overflow into the streets.
"What would have to happen is the storm drains would have to be clogged and fill up and burst, and I can't imagine that," Mr. Balog said.
The power grid
Baltimore Gas and Electric Co. officials are also confident that the city's power grid is adequately protected from any potential disaster. To reduce the risk of damage from flooding, for instance, BG&E; transformers around the Inner Harbor are installed at least 10 feet above water level, said Bruce W. Masland, the utility's general supervisor of engineering and operations.
The power company maintains 26,000 miles of underground wire and cable in Central Maryland.
In any particular area, a major storm, a fire or flood is capable of taking some area out of service.
But "we have for years been trying to engineer this system so it doesn't go out of service," Mr. Masland said.