Several different ways you could go about this - but all depends on what your end goal is...
Does it need to be realistic?
Does it need to be 3d? (any camera movement during the explosion?)
A few options for the explosion itself:
1. Composite in an actual video of an explosion in post
2. Particle (sprites) explosion in Maya
3. Fluid simulation (if you have MayaUnlimited)
4. 3rd party dynamics sim like RealFlow or Glu3D
You'll also need to find a solution for handling the destruction of the pump, like Blastcode's Kiloton/Megaton or Maya's internal rigid body dynamics...