Regulatory Requirements Regarding Diking

There are several specific regulatory documents governing the siting, design, and capacity of impoundment systems. For flammable materials, these requirements are outlined in the LNG Federal Safety Standards, 49 C.F.R. 193 (1990) and the National Fire Protection Association s Flammable and Combustible Liquids Code, NFPA 30 (1990). For toxic materials, similar design guidelines are specified in the sections of the Code of Federal Regulations (C.F.R., EPA Section 32 and EPA Section 40). 

The Federal safety standards included in 49 C.F.R. 193 (1990) define four classes of impounding systems ranging from dikes constructed within 24 inches of the component served to remote impounding spaces (see 49 CFR 193.2153). The structural requirements specify performance reliability and integrity as a result of imposed loading caused by a full liquid head of spilled material, erosive spill action, thermal gradients, fire exposure, and catastrophic rupture of storage or transport vessels into or near the system (see 49 C.F.R. 193.2155). 

Part of the Environmental Protection and Enhancement Act, 32 C.F.R. 650 (1992), specifies minimum plan requirements for the spill control of oil and hazardous substances. Preventive containment measures are recom- 

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