PERSONNEL SHELTERS
The individual personnel shelter is designed towards the following goals:
* An expedient shelter which can be constructed in 7 days by ordinary individuals.
* Designed to house and shelter 40 persons.
* Uses common building materials.
* Provides greater than 50 psi blast protection.
As a frame of reference, winds from a blast wave of 3 psi overpressure are sufficient to kill a person caught out in the open. A typical residence will collapse by an overpressure of 5 psi. A blast wave of 10-12 psi will convert most large office buildings into rubble. At 20 psi, reinforced concrete structures are leveled.
This shelter is designed for a 50-psi blast. The shelter should survive the blast wave as close as 520 miles from the point of impact of a K/T size impactor.
In order to achieve the 50-psi blast protection goal, the shelter is designed as:
* An underground shelter.
* Earth arching construction.
* Shored sidewalls.
* Covered entrance.
Earth arching increases the load-carrying capability of buried structures.45 It allows the soil to redistribute the blast load evenly into "arches" which transfers the load away from the structure. In order for earth arching to occur, the following conditions must be met:
* The structure must be above the water table.
* The structure cannot be built in water saturated soil.
* The structure must be buried in granular soil or the site must be backfilled with granular soil.
* The depth of earth covering above the structure must be at least one-half of the minimum span of the structure.
* The structure must be flexible enough to yield under the applied load.
This structure is designed with shored sidewalls. During the 1950-1970, the U.S. government conducted a number of blast tests on various shelter designs. In October 1976, the DICE THROW tests exposed a number of expedient shelters to the blast from a 600-ton ammonium nitrate-fuel oil explosion. One of the findings from this test program was that unshored covered trenches collapsed from ground motion at relatively low overpressures.
This design also eliminates the inherent weakness in shelter doors and entranceways. The entranceway is buried under granular soil.
In order to make the construction process easier; I have organized construction into the following steps:
Comments Prior to Construction:
* Before you begin the process of site construction, determine the type of ventilation/filtration system to be used. If you decide to use the handcrafted plywood double-action piston pump designed by Cresson H. Kearny, turn your best woodworkers loose to construct the 20 units needed for the complex, in order that these units may be ready when you reach Step 8.
* Form a team to construct the carbon dioxide scrubbers. The quantity of scrubbers required is a function of the pumping capacity of the air pumps. A common tire pump will only move around 0.9 cubic feet of air per minute. One type of air pump moves significantly greater volumes of air. These are pumps use to inflate rubber rafts. For example, the Stearns Double Action Hand Pump (~$18.99) will move 7 cubic feet per minute. The Sevylor Riverboat Air pump (~$19.99) will move 9 cubic feet per minute. At the top end, the Carlson Barrel Pump (~$199) will move 18 cubic feet per minute.
* Form a team to solve Stage 1 & Stage 2 water needs.
* Hammocks may need to be fabricated by hand. If so, create a team to meet this objective.
* I recommend that if time permits, that you construct one shelter to begin with to get a feel of how things go together. Then construct the other 19.
* Recheck lumber lengths and recut for precision, if necessary. A few extra inches in length can throw the dimensions of the shelter off and make construction more difficult than it needs to be.
* The goal is to construct a shelter that will survive the blast of an impact. Some building materials will be in short supply or unattainable. This plan is not set in stone. Use your imagination and ingenuity to find substitutes or alternatives. If possible, error on the side that will provide the shelter greater strength rather than weakening the design. But life is not perfect. (Keywords: be flexible, be innovative)
Other Alternatives
Several other alternative designs or approaches exist for surviving a large comet impact:
* Existing Underground Shelters
* Caves, Tunnels & Mines
* Underground Homes
* Expedient Shelters
* Above Ground Shelters
* Endless Alternatives
Existing Underground Shelters
Probably top on the list of alternatives is existing underground shelters. These include atomic bomb shelters, storm shelters and root cellars. Some of these types of shelters may perform very well against the blast effects of a comet impact and the subsequent earthquakes. Atomic bomb blast shelters should be high on this list. Other types of underground shelters, such as root cellars may be weak and provide only minimal protection and may need significant strengthening to survive the blast effects. Fallout shelters should not be confused with blast shelters. Fallout shelters are designed to provide protection against radioactive fallout, not necessarily the blast effects of an atomic bomb detonation or a comet impact.
Caves, Tunnels, Mines
Depending on the area, another alternative approach is to use natural or existing man-made structures including caves, mines and underground subway tunnels. In general, with some modifications, these structures could be converted into acceptable Stage 1 personnel shelters.
Mines and caves represent a large potential source of shelters. Data from the Bureau of Mines was compiled into a National Underground Mines Inventory. This database is maintained by FEMA. It identifies approximately 34,764,000 individual shelter spaces that could be created in U.S. mines. It is estimated that 2 to 3 million spaces could be created in tunnels, 4 million spaces in caves, and a potential for up to 100 million spaces in mines (60-70 million in limestone mines, 20-30 million in salt mines, and 5 million spaces in gypsum and sandstone mines.)45
In the case of shelters buried far below the Earth, such as caves, consider the following points. First, they have the advantage of withstanding atmospheric and surface hazards fairly well. They will be fairly immune to blast effects, falling debris, and firestorms. But they also have a few weaknesses. Expect sizeable earthquake activity after impact. This could result in cave-ins. Be prepared to dig or blast your way out. Another problem is that many poisonous gases are heavier than air. These gases may gravitate to underground structures. Also since they may be open structures, they may not be immune to the effects of flooding or of a tsunami. For the above two reasons, I recommend that you consider sealing off the opening (very well) prior to impact.
Underground Houses
Earth sheltered residences or underground homes have the potential of becoming acceptable Stage 1 shelters that will survive the blast effects of a comet impact. These homes may require some modifications. In many designs, the front wall of an underground house is completely exposed. This exposed wall will need to be buried in granular soil.
Expedient Shelters
Chapter 7.3 of the Oak Ridge National Laboratory report Civil Defense Shelters: A State-of-the-Art Assessment - 1986 provides construction plans for several expedient shelters designed to protect inhabitants from a 10-100 psi overpressure blast.45 Some of these designs are very back-to-basics. You go out into the middle of the woods with nothing more than a shovel, a machete, and a good pair of workgloves and over the course of one to two days construct a shelter out of saplings. Be sure to bring along medicine for the blisters. These shelters are quick to construct and more importantly these shelters are tested, proven designs. These shelters should provide protection from the blast effects of a large comet or meteor impact.
Above Ground Shelters
Many locations will not support the construction of underground shelters. For example, limestone may lie a foot below the topsoil. The following alternate, aboveground blast shelters, is proposed for these environments. The layout of this design is very similar to the below ground design described above. The major difference is the shelter will be located above ground and the earth walls will replace the plywood sidewalls.
One advantage of this design is that aboveground shelters could be converted into a usable Stage 2 shelter.
Endless Alternatives
Ingenuity can provide an endless supply of alternatives. Large corrugated metal pipes can be buried in granular soil and be converted into shelters. In-ground swimming pools might provide a foundation for a shelter. New spring tanks or septic tanks could be buried and turned into a shelter. Railroad coal cars could also be buried and be converted into shelters.
NEXT | PREVIOUS | OUTLINE | HOME