All construction jobs are temporary. The primary value of the project is in providing a lower cost domestic alternative to imported oil.
The Enviro-nuts are always opposed to any economic development, anywhere. In America, that is. China can build all the smoke-belching, river-contaminating factories they want, and nary a peep is heard from the Sierra Club, et al., all of whom seem to think that CO2 is a terrible planetary poison, as opposed to what is truly is: plant food. Never mind that the additional amount emitted by the pipeline in question would be negligible and essentially unmeasurable.