NFPA 329-1999 Recommended Practice for Handling Releases of Flammable and Combustible Liquids and Gases.
4-2.5 If all the equipment appears to be in order and there is no obvious sign of spilling or dumping into sumps or sewers, the grounds and areas around the premises should be checked. The following guidance will be helpful in checking the area. (a) Signs of waste liquids that have been dumped or spilled onto the ground should be identified. Any areas of con- tamination that could have been covered up, such as fresh gravel, sod, or soil, should arouse suspicion. (b) Nearby streams and bodies of water should be checked for signs of flammable or combustible liquids, such as a sheen or slick on the surface of the water and along the banks. (c) Vegetation should be checked for an indication of dam- age from spilling, dumping, or contaminated groundwater. (d) A photoionization detector or other appropriate instru- ment should be used to check sewers and other underground con- duits and cavities, such as utility manholes, for the presence of vapors and a visual inspection should be made for signs of foreign liquids on the surface of any standing water in these areas. (e) The barrels of any fire hydrants in the area should be checked. (f) Nearby excavations and steep cuts or natural slopes down-gradient from the potential source should be checked for signs of liquid. 4-2.6 Dumping or spilling flammable or combustible liquids into sewers or on the ground could be a violation of state or federal law and should immediately be reported to the proper authorities. 4-2.7 Small spills do occur inadvertently and could appear to be larger than they really are. A small amount of liquid (e.g., 1 cup of fuel) spilled onto wet pavement will spread over a rel- atively large area. Small spills that spread out over a large area will dissipate rapidly and are not likely sources of under- ground contamination. The significant releases are large spills and repeated small spills that can flow to points of access into subsurface structures or porous soils and then reach the groundwater table.
5-1 General. 5-1.1 All data previously gathered should be reviewed to deter- mine the most efficient method or methods of testing. There are several methods described in this chapter that can reveal a leak prior to conducting a tightness test. If one of these preliminary techniques does not reveal the source of a suspected leak, it can- not be concluded that the liquid-handling system is tight. But the possibility of quickly solving the problem will often warrant the limited effort involved before a tightness test or other release detection method is undertaken. For additional details on the latest testing and release detection methods, industry publica- tions and officials should be consulted. 5-1.2* Regardless of the procedures involved, liquid-handling equipment should be evaluated in a manner that is as close as possible to normal operating conditions. Excessive pressures or tests by nonrepresentative liquids could indicate a leak where none exist or could conceal leaks that do exist.
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