A complete structural failure of a high strength 36-inch outer diameter pipeline with the wall thicknesses of the proposed Project pipeline (see Section 2.3.1, Table 2.3.1-1) would be a highly unlikely event. To cause such a failure, the proposed pipeline would likely need to experience a direct shear event. Such events could be caused by:
A strike-slip fault movement across the proposed pipeline – however, the proposed pipeline corridor does not cross any known active faults;
An anchor drag event or a collision event within a navigable river that experiences large to very large ship or barge traffic – however, all such river crossings along the proposed corridor would be crossed using HDD and the pipeline would therefore be installed well below the maximum anchor depth and outside any potential collision hazard;
A major construction-related accidental equipment interaction with the buried pipeline – however, the proposed pipeline would be buried under a minimum of 4 feet of cover, would be clearly marked, would include warning tape (ribbons) as required by the Project-specific Special Conditions developed by PHMSA, would be predominantly routed through rural areas where such large equipment construction impacts would be rare, and Keystone would implement public awareness and damage prevention programs in accordance with 49 CFR 195.440 and API RP 1162. Additionally, the probability of puncture of the X-70 strength steel pipe of the proposed Project would be very low as its puncture resistance is in excess of 65 tons and approximately 98 percent of all excavators in North America have a maximum digging force of less than 35 tons and no excavator has a digging force greater than 40 tons;
An intentional act of sabotage, vandalism, or terrorism – however, the pipeline would be buried with a minimum of 4 feet of cover and all aboveground facilities would include security fencing, thus reducing facility accessibility to these potential threats;
A major flood event with the potential to cause deep scour and debris impact to the proposed pipeline – however, at major river crossings, the proposed pipeline would be installed using HDD and would therefore be below the maximum scour depth, and at all stream crossings, the proposed pipeline would be installed below the calculated scour depth;
Crude oil released from the proposed pipeline during operations or refined oil released during construction or operations into the environment may affect natural resources, protected areas, human uses and services, and aesthetics to varying degrees, depending on the cause, size, type, volume, location, season, environmental conditions, and depending on the timing and degree of response actions. Small oil spills (e.g., minor intermittent leaks and drips from construction machinery and operating equipment) would be almost certain to occur during construction and operation of the proposed Project, although in aggregate these spills could be of sufficient magnitude to substantively affect natural resources and human uses of the environment.
http://www.keystonepipeline-xl.stat..._3.13_Potential_Releases.pdf?OpenFileResource
...more to come..
