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         transported (weliheads or pipes). H2S is highly flammable with
         explosive limits similar to gasoline. Hydrogen sulfide will not
         spontaneously combust under normal conditions. However, adjacent
         fires may be sufficient to cause combustion. Personnel operating
         around wellhead or pipe fires will be at risk if the H2S is
         ignited.


             f. Summary and Recommendations

                   1) The results of the study are summarized in the
         following paragraphs.

                        a) The chemical threat in the MARCENT AOR is
         three-fold: the threat from fires due to ignition of petroleum
         products; the threat from toxic gases such as ammonia and
         chlorine; the threat of hydrogen sulfide and fire from the oil
         wellheads and pipelines.

                        b) The fire that would result from an explosion of
         tanks containing petroleum products would be significant. The
         greatest amount of damage would be to individuals within 500 feet
         of an explosion. Outside of 500 feet, the Ml7Al mask will provide
         protection against various combustion products from the fire. If
         the air becomes saturated, however, breakthrough of the masks
         will occur. The MOPP suits provide sufficient pr6tection.

                        C) The Ml7Al provides limited protection against
         certain petroleum products. After 15 minutes of exposure to these
         products, breakthrough of the mask occurs.

                        d) Ammonia and chlorine are toxic gases. Whether
         or not either of these gases pose a threat to critical sites
         depends on wind direction. Wind direction is variable in this
         region of Saudi Arabia. Therefore, the effect of releases of
         gases on a particular site is difficult to predict.

                        e)  The instantaneous release of either of these
         gases, even when minimal storage amounts assumed could be
         problematic. If the release occurs during the daytime, the
         windspeed is sufficiently high that the lethal clouds of the
         gases can reach critical areas in a short amount of time. The
         nighttime scenario is better in that the lethal cloud travels
         more slowly. Nevertheless, the lethal cloud is larger in this
         case because the low windspeeds at night disperse the gas less.

                        f) The time needed for the lethal cloud to pass
       - over depends on windspeed. Clouds will pass over a fixed point on
         the ground faster during the day than at night because of the
         higher daytime windspeeds.

                        g) If either an ammonia or chlorine tank is
-~       ruptured, the resulting lethal cloud is independent of the ainount
         of gas orignally in the tank. However, the cloud will persist

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