Environmental leakage, sources

About 80% of public fleets use central refueling, but only about one third of business fleets do and most of those also use commercial fueling stations. Most fleets that centrally refuel use outside sources for at least 15% of their refueling. The Environmental Protection Agency (EPA) has had major concerns over fuel leakage and underground water contamina-... 

Transient and Steady-State Conditions From the landmine studies we readily conclude that the source term for these molecules has an initial spike, or increased rate, in the days or weeks after the mine is placed. This rate then decreases to some more or less constant level and may remain at that level for years. The initial spike comes from surface contamination, while the long-term rate is primarily from diffusion through the case and seals or leakage through imperfections or damage. The rates are clearly subject to environmental factors, principally temperature and soil wetness. Nevertheless, it seems clear that, at least in the case of landmines, there is a continuing flux of molecules that provide a potential for detection. 

The first priority in any spill is to stop the source of leakage. The second priority is to contain the spiU so that further environmental damage does not occur. Spills on water can be contained using the many commercial spill containment booms. Booms will contain floating liquids up to a relative speed of knot. This is an important limitation because in many situations this velocity is exceeded. Attempts to contain oil on some open waters and across tidal bays will be futile. Tidal currents often exceed 2 knots and can be as much as 8 knots. Placement of booms requires extensive manpower and time. 

There is no specific detailed guidance available in the industry or from regulatory bodies on the siting of combustible gas detectors. Due to the wide variety of material that needs to be detected, variances in ambient environmental conditions, variations in process composition, temperatures and pressures, the ability to predict the manner in which gas releases can be detected by placement to detectors is not available as of yet. Most detectors are suggested to be placed near sources of potential leakages. For example, per NFPA 15, gas detectors are to be located with consideration for the density and temperature of the potential flammable gas release and its proximity to the equipment where leakage could occur. In API 14C (for oflshore structures) gas detection is to be provided in enclosed classified areas, in all enclosed areas that there is natural gas fired prime movers, and in buildings where personnel sleep and there is a flammable gas source. 

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