The Next L.A. / Reinventing Our Future : Taming the Land

“A metropolis that exists in a semidesert, imports water 300 miles, has inveterate flash floods, is at the grinding edges of two tectonic plates, and has a microclimate tenacious of noxious oxides will have priorities among the aspects of its environment that it attempts to control.” - John McPhee, “The Control of Nature”

Is anywhere completely safe? The answer is no. The strongest freeway overpass ever engineered will topple if it’s sitting on the epicenter of big quake. Your house may be quake-safe and perched on the local granite, but if it is, it’s likely to be near a chapparal-covered hillside that will one day become an inferno. You may be on “The Flats,” safely away from burning hillsides and beach erosion, but guess what: The potential for urban flooding by the Basin’s arid rivers is vast.

The metropolis is not for the timid, nor is it for the arrogant. The city will come back from this latest nightmare, full of new ideas for rebuilding and retrofitting, but remarkably short of ways to get residents out of the danger zones. We love our panoramas from hilltops above the smog, even if the hills explode from time to time. We love our hilltop panoramas and ocean views, even if we’re threatened by fire and mud. We want our summer weather in January, and we’re willing to risk a few bricks and some freeway overpasses to have it.

ZONING FOR DISASTER

Just before the Northridge earthquake, predictions envisioned a Los Angeles whose population would grow by about 2 million--to a total of more than 11 million--by the year 2010.

The temblor may slow down that growth: Quake-weary people could leave, fewer immigrants could come here. But birthrates and continued immigration still are expected to keep the population growing and increase the need for decent housing--particularly housing that families can afford--and the jobs to support it.

Some zoning and planning changes may result from our recent cycle of natural disasters. But experts say that wide and stringent no-growth rules are unlikely to be passed--even for fire, flood and seismically risky zones. Any earthquake-related zoning is complicated by the sense that much of developed Los Angeles County could be liable to temblor damage.

“To suggest that you are not going to rebuild in urban Los Angeles--that’s beyond the pale for political discussion,” said William Fulton, editor of the California Planing and Development Report. Instead, he and others predict the emphasis likely will be on rebuilding and retrofitting for more safety.

BUILDING IN EARTHQUAKE COUNTRY Since the 1933 Long beach earthquake, the city has periodically strengthened its building codes, usually after a major quake exposed new weaknesses. In 1973, for example, two years after the Sylmar quake, the city building code for new apartments was amended to require plywood in exterior walls to help resist sideways stress during earthquakes. Ten years after the Sylmar quake, the city began requiring owners of unreinforced masonry buildings of more than four units to strengthen walls to prevent collapse.

On Feb. 1, the City Council passed an ordinance requiring buildings with so-called prefabricated “tilt-up” walls--walls lifted into place but without sufficient binding to their roofs--to reinforced the connection between walls and roofs.

Officials are also considering measures to retrofit other types of buildings damaged in the earthquake: non-ductile concrete structures, including hospitals; older woodframe buildings that lack plywood reinforcement in stucco walls; and precast (concrete) parking structures, several of which suffered major damage.

City officials are also considering whether to require retrofitting some older homes, in particular woodframe dwellings that lack plywood or particle-board sheathing that connects floors with foundations.

Such measures are costly, but future construction may be affected.

The Quake-Safe House

Is it possible to build one? Here is a list of possibilities, ranging from realistic to way out there:

* Steel-frame construction to flex in a quake and resist fire

* Shock-absorbing base or floating foundation to resist shocks

* Deep-drilled piers to steady house in liquefaction zones

* Automatic shutoff valve to close down gas meter

* Flexible plumbing that won’t break in a quake and resists extreme heat

* Light metal prefabricated chimneys that can be secured to the frame; fireplace could be converted as a grill or oven in emergencies

* Diesel or propane-powered generator with battery packs for electricity

* Rainwater recovery system funnels it into holding tanks for later use

* A large vegetable garden to supplement diet when stores are shut down.

WATER IN THE DESERT

Southern California is a desert, prone to years of drought. Wet years, however, can be memorable. Despite the region’s vast network of catch basins, storm drains and ugly concrete river channels, the federal government considers the Los Angeles and Santa Ana rivers to comprise one of the largest flood threats west of the Mississippi River. Yet development pressures are unrelenting, with such major flood control basins as the Hansen Dam presenting the tantalizing prospect of some of the latest undeveloped land in urban Los Angeles County.

So much of the region is flood prone that the odds are against any major rezoning.

Building for Flood

Most builders have this advice for those contemplating construction in a flood zone: Don’t. The lengths required to construct such a fortress are enormous. Consider:

* Raise the foundation level by bringing in fill dirt and raise it above the flood plain level. It may be helpful to build a concrete block wall around the fill (Fill dirt, however, may be seismically unsound)

* Build a “riprap”--often seen in flood control channels--along the upstream side of the pad to divert water and control erosion (A riprap is made of two chainlink fences with boulders between them)

* Pilings should elevate the house above the so-called 100-year-flood level. They must meet seismic and soil requirements

* Build a dike around the house, with a bridge driveway so floodwaters won’t be blocked

* Pumps should be placed inside the dike area to pump out water that may build up during a rain

THE COASTAL QUESTION

Standards for building along Los Angeles County’s coastline vary according to different coastal communities and the California Coastal Commission, which issues permits for building in those areas that have not adopted plans.

Typically, coastal plans require both environmental and geological analyses that consider the potential for landslides and earthquakes.

Sophisticated building techniques have made slope construction safer than in years past, but environmental issues remain in coastal wetland areas from Ventura County to San Diego County.

The problem of beach erosion surfaces with each heavy winter storm. Communities from Malibu to Seal Beach must often take drastic--and very expensive--measures to protect shoreline development from encroaching waves.

The political will seems to exist to take action where coastal development is concerned, but costs could stand in the way.

THE ANNUAL INFERNO

Southern California’s storied hillsides nurture native vegetation that is literally explosive. Many types of chaparral plants reproduce only after a wildfire has moved through. But these hillsides also provide what much of the area can’t: a rural feel, scented air, spectacular views of ocean and city. They are among the most desireable, expensive real estate in California. And they burn.

Fires are a complex phenomenon, creating, as they do, the danger of flood and mudslide in denuded watersheds. The fall’s devastating wildfires--terrible, but not the worst the area has seen--renewed the endless debate on whether it is advisable to build where brush fire is inevitable. Financially strapped governments at all levels are increasingly hard-pressed to devote the resources required to ensure safety before a fire and to rebuild after.

Building for Fire

As much as the quake, the fires provided vivid and sometimes visual examples of what works and what doesn’t. For houses in fire zones, experts advise these measures, among others. Many are aesthetically distasteful, and others are prohibitively expensive:

* Houses set back as far as possible from slopes to avoid fires racing up hillsides.

* No flammable roofs. Roofs must be non-combustible with no gaps or places for embers to lodge. No wooden decks or fences.

* In areas that abut wildlands, non-combustible stucco siding or stucco over cement building panels.

* Double-glazed windows, fireproof curtains.

* No tree or tall shrub within 30 feet of the house. No juniper, eucalyptus or other “pyrophytes”

* Wider streets to ease access for firefighters and trucks

* Swimming pools should be accessible to firefighters’ pumps. Owners might be required to own pumps and do their own firefighting until help arrives

Mapping Disaster

Clouds of aftershocks mark the lingering effects of the 6.7 Northridge earthquake in this computer-generated topical map, above, created for The Times by Caltech. Southern California’s arid terrain, sculpted by eons of quakes, is also host to the tinder-dry and highly explosive vegetation known as chaparral. Fragile watersheds and mountain slopes ringing from the Basin are vulnerable to wildfire.

PLANNING FOR PREVENTION

Just a few of the myriad dangers identified by Los Angeles County’s Department of Regional Planning are shown below: soil liquefaction in earthquake, faults and historic epicenters, landslides and floods. The maps show that there are practically no areas affording total safety from potential disaster.