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Land, wind and rain: planning for disaster.

Land, Wind and Rain: Planning for Disaster

A hurricane lashes the South Carolina coast. An earthquate devastates the San Francisco Bay area. As if we had become too complacent, events of the past few months have driven home the fact that nature is unpredictable, powerful, and very dangerous.

As many parts of the country look ahead to weeks of heavy snow and spring flooding, it is important to keep in mind that even when natural disasters can be predicted, they cannot be prevented. However, a risk manager can do a great deal to prepare for disasters and protect property.

A well-formulated preparedness plan, developed with help of a loss management consultant, can cut property losses from a natural disaster significantly. The first step is to determine which natural disasters could strike your facility. Next, develop an action plan that weighs the potential damage with the cost of preventive measures. Evaluate areas of your property that can be improved now to minimize damage should a disaster occur. Finally, have a comprehensive salvage plan that can be implemented as soon as possible after the disaster.

Earthquake

A review of the San Francisco earthquake from a property conservation perspective makes one thing clear: We've still got a lot to learn about earthquakes and their effects. An understanding of the very nature of earthquakes, and of how to minimize seismic damage, is still evolving.

There are several phenomena related to the earthquake that can cause significant property damage. The first and most obvious is the rupture along a fault line at the surface of the earth, in which two adjacent sections of the earth break apart and move in different directions. Anything located on or near the fault break will be subjected to severely destructive forces.

Buildings at greatest risk are those whose construction includes unreinforced masonry. Many older buildings, pre-1930 or so, have no reinforcing steel. The masonry is unforgiving and has little ductility or elasticity. These buildings are particularly vulnerable to shears (lateral movement) or tension.

Settling, tilting, or even toppling of buildings is even more likely in areas with poorly compacted or water-saturated soils. A prime example of this effect occured in the Marina district of San Francisco, which was a former marsh that had been filled.

Flooding caused by earthquakes can be another source of extensive damage. During an earthquake, dams can give way; landslides can force water beyond the normal waterline; and in coastal areas, tsunamis or giant sea waves, can destroy coastal property.

Fire is often the most serious source of damage during an earthquake, as it was during the 1906 San Francisco quake. Piping and vessels containing flammable liquids and gases may rupture and leak. Damage to wiring and electrical equipment creates potential ignition sources. By the time a fire begins, protective equipment such as sprinklers, hydrants and alarms may already be incapacitated.

Building damage erom an earthquake occurs when horizontal and vertical forces set against the inertia of the structure and exceed its earthquake resistance. Building codes designed to minimize damage from earthquakes continue to evolve, as ongoing engineering studies assist in designing buildings that are better able to withstand seismic disturbances. In areas where serious earthquakes are expected to reoccur, new buildings should be designed in accordance with the latest provisions of the Uniform Building Code.

In general terms, successful earthquake resistance is achieved through: design and construction materials resistant to vertical and horizontal forces imposed by ground shaking; a properly designed foundation that rests on acceptably firm soil; and main structural elements (walls, roof and floor slabs) that are properly tied together so that they will not separate. Exceeding code requirements should be considered for facilities that have an impact on continuity of operations, such as power plants and computer centers, or where services will be needed during or after the earthquake, such as fire stations or hospitals.

Existing buildings in earthquake-prone areas should be studied to determine if an upgrade is in order. All buildings should be inspected periodically for deterioration of structural details that affect resistance to seismic forces. Similarly, any proposed changes to a structure that could affect its resistance, such as cutting an opening in the wall, should be carefully considered before work begins.

For many risk managers, protection of what is inside the building is more important than the building itself. And while a seismic code may provide for building protection, the building's contents are the responsibility of its occupants.

Equipment can be damaged in a number of ways during an earthquake. Tall, slender equipment such as transformers may topple. Boilers, tanks and wheeled equipment may slide or inch-walk across the floor. Piping may snap or bend. Foundations may settle, causing considerable damage to interconnect equipment.

Each of these potential problems can be prevented or minimized. Toppling and sliding can be reduced by cross-bracing and anchoring the base of the equipment. Piping can be safeguarded by providing adequate clearance where a pipe passes through a wall or floor and by using flexible couplings and sway bracing to allow limited but not damaging movement. On lines carrying hazardous materials, install automatic or shock-actuated shutoff valve. Mount interconnect equipment on the same foundation pad.

Major equipment should be supported independent of the building. Where plumbness is vital, a manual levelling system may be feasible on some equipment. In general, an integrated seismic protection system is needed to withstand the forces of an earthquake and shut down safely.

Fire protection systems and equipment deserve special attention. Sprinkler piping should be installed with sway bracing, flexible couplings and welded connections to allow a degree of movement without excessive vibration. Proper foundation and bracing is needed at fire pump installations.

High Winds

The term `High winds' usually brings to mind the powerful, dramatic winds of hurricanes and tornadoes. Indeed, these two wind types carry the most potential for damage in terms of both geographical coverage and duration of the storm, but the smaller gale and squall winds also threaten property.

Winds can damage much of the exterior of buildings, as well in addition to items and equipment left outside. The first concern is the roof. The windward side of a roof receives direct pressure from the wind, while the leeward side is subject to the wind's lifting force. In addition, strong winds can sweep through open or broken windows and pressurize the inside of the building, adding a lifting force on the roof's underside.

Roofs under repair are particularly vulnerable regardless of whether they meet construction standards. One plant in South Carolina during Hurricane Hugo in August, for example, had removed a section of its interlocked roof system for repairs early in 1989. Several hundred square feet were left exposed to the winds of Hugo. Not surprisingly, the winds entered the building through the hole and caused significant internal damage.

The unique makeup of a tornado can utterly destroy a building from the inside out. The extremely low air pressure inside a tornado funnel causes a sharp drop in the air pressure around any building it passes. The higher pressure inside the building forces out the walls, literally exploding the building.

Other areas where winds can damage a building are roof insulation, roof coverings such as skylights and roof-mounted equipment, doors, windows, parapets, canopies, eaves and balconies and walls (cladding). There can also be damage from wind-blown objects and from equipment left outside in addition to flooding from torrential rains and, in coastal areas, from ocean waves. Buildings under construction are also at risk from high winds. Vulnerable areas include steel frame structures, masonry walls, and roofs under construction.

All too often, when people hear of an oncoming hurricane, some may feel resigned to damage. A building can be designed to withstand certain wind forces. Reinforced concrete buildings, for example, survive wind better than other types of construction.

Recommendations for wind resistance are available from loss consultants. Unfortunately, not much can be done to prevent the "inside out" collapse of buildings described above. One option is the use of substantial building materials, such as reinforced concrete, in cases where cost is not prohibitive. Buildings in tornado-prone areas may have shelter modules, which are built to withstand wind forces up to 150 mph. This kind of shelter can be used to protect computer rooms and other valuable equipment.

During a storm, it is important to be prepared for secondary causes of damage, such as flooding from the rains that usually accompany wind storms. If storms threaten your facilities for a length of time, have personnel patrol the buildings and look for structural damage, fire, and leaks. Once the storm has passed and the waters have receded, restore any impairment to fire protection, pump out flooded areas, and remove silt and debris.

It is advisable to look for live power lines, leaking flammable gases, flammable liquids and structure in danger of falling. Then, separate damaged and undamaged material, cover equipment and stock against further exposure, and remove combustible debris to a safe place.

Floods

Whether or not a facility is at risk from floods is a question that should be answered before construction begins. It usually boils down to a matter of geography. Mostly, areas at adjacent to a body of water that has flooded in the past or could possibly flood.

Within flood plains are a number of "flood zones," which are labeled according to the recurrence interval of floods with each zone. For example, an area which floods every 50 years is a 50-year zone. The greater the time interval, the greater the severity.

Known flood plains are indicated in reports and maps available from the U.S. Army Corps of Engineers, the Federal Insurance Administration, and the U.S. Geological Survey. A loss prevention consultant can also help you gather and evaluate this information.

As a general rule, it is advisable to avoid building in a flood plain. The reasons to avoid building in a flood plain are obvious--flood damage can be all-encompassing. Everything from equipment to the building itself may become soaked and subject to further damage from the force of the water's flow. The aftermath is no better: heavy deposits of silt and debris may be left behind, making cleanup and salvage a slow, expensive operation.

The most straightforward method protecting your property from flood--keeping the water out--may seem at first glance obvious, and at second glance, impossible.

It can be achieved, however, by permanent protection measures. Buildings in high-risk situations, for example, a facility with high-value equipment which lies within a 100-year flood zone would require flood walls and dikes. These are the most effective forms of permanent protection--and also the most expensive.

Other less expensive permanent measures include: bricking ground-level windows, installing floor doors of aluminum, steel or wood, which are suspended above doors and windows and then rolled into place; installing hand-operated valves in piping to prevent back flow through floor drains or plumbing fixtures; and building low walls around vital equipment (boilers, computers, etc.) to keep out small amounts of water.

A less expensive, but still effective, degree of flood protection is provided by contingent protection measures. As the term "contingent" implies, the shields are not installed permanently but are kept on hand to be used if a flood warning is received. Brackets are permanently anchored on door and window frames so that the shields can be quickly bolted into place. To prevent last-minute confusion, shields should be numbered to correspond to the appropriate door or window.

The third protection level is emergency protection. It depends on proper planning, enough people to carry out the plan, and sufficient warning of a flood, and should only be relied on when all of these elements are available. Emergency planning procedures include: sandbagging possible water entry points; relocating stock to higher stories or safer buildings; covering large stationary machines with water-displacing, rust-preventing compounds or large plastic sheets; and filling empty storage tanks to prevent them from turning into floating battering rams.

The success of emergency protection, in particular, requires trained personnel on call. For flood duties, assign only those employees who live outside the flood-prone area. Because their homes and families are safe, they can concentrate on their important jobs. Duties can include filling and placing sandbags, securing flood shields, and relocating equipment and stock.

Snow/Freeze-ups

Heavy winter weather brings two distinct problems to the risk manager: roof collapses and freeze-ups of mechanical and electrical systems. A recent loss study showed that the majority of roof collapses are caused by ice, snow or hail (or from "ponding' of the melted precipitation). Most sizeable snow load collapses occur in the lower portions of flat, multi-level roofs, where snow accumulates after blowing off the higher sections.

Curved roofs and canopies are also subject to collapse, due to drifting of snow from windward to leeward areas of the roof or from rooftop to canopy. The age of the roof is not always a determinant of its susceptibility to collapse. In fact, most snow load collapses have involved boards-on-joist or steel frame roofs of modern construction.

Inside the building, freezing temperatures can play havoc with mechanical and electrical systems. The most frequently damaged system is the fire sprinkler system, followed by domestic water. Other systems that suffer during freeze-ups are process piping, compressors, instrumentation, valves and fittings, heating and air conditioning equipment, steam piping and boilers.

Although it may seem less drastic than the other situations discussed here, freezing can be disasterous. During December, 1983, for example, Factory Mutual Engineering Association worked with businesses that suffered the prolonged freezing weather throughout the United States and Canada. Hardest hit were those areas that do not usually experience such low temperatures, and those that were idle during the holidays, and thus unprepared. The result was more than $67 million in property losses, almost 20 times the losses experienced in the winters of 1985-86 and 1986-87 combined.

New roofs and canopies should be designed to resist the snow loads which are required by local codes. Existing roofs may need to be reinforced if the roof design cannot anticipate the snow load as outlined in the report.

At locations where loss expectancy is not high, snow removal teams can be assigned the task of maintaining a clear roof. A safe maximum snow depth should be determined, and appropriate snow removal equipment should be readily available.

To protect a roof from ponding, design the roof with sufficient drainage. Factors such as pitch, roof stiffness, and drain location should be taken into account. Once installed, drains must be made available to melting water. Maintain clear paths through the snow and ice to allow melt-off to run to drains and eaves.

To protect against freeze-ups, establish an inspection schedule and repair procedures for all systems subject to freeze damage. Appoint someone in management or operations to oversee weather monitoring and implementation of cold weather procedures.

If a facility will be left unattended during the winter, a central station supervised alarm system should be provided to monitor power supply, building temperatures, low-water fuel trips on boilers, water temperatures on exposed water storage tanks, and selected process controls. The alarm system should be set to activate before temperatures drop below 40 [degrees] Farenheit.

Heating and insulating systems of buildings and equipment-prone to damage from freezing temperatures should be designed to keep the temperature at a minimum of 40 [degrees] F as well. To determine the type of insulation necessary, use as a guideline the lowest outside temperature experienced in the area. This information is contained in the American Society of Heating, Refrigeration and Air-Conditioning, Inc. Handbook.

Be sure that areas of the building that are susceptible to freezing--stairwells and out-of-the-way places--have enough heat. Install emergency heating equipment in freeze-prone areas, and set the equipment to activate automatically when temperatures fall to 40 [degrees] F.

PHOTO : Two firefighters scale a ladder to survey some wreckage after the recent San Francisco

PHOTO : earthquake.

Larry Chase is vice president in the Standards Division of Factory Mutual Research Corporation.
COPYRIGHT 1990 Risk Management Society Publishing, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Author:Chase, Larry
Publication:Risk Management
Date:Jan 1, 1990
Words:2663
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