Excavation (and infiltration) near electricity poles?

[Drellingore]

1. Are there any regulations about how close to an electricity pole you're allowed to excavate?
2. Are there any regulations about how close to an electricity pole you're allowed to put a drainage field, or non-BS6297 infiltration system?
3. How do I find out if there's a wayleave between UK Power Networks and (I guess) us?

 

There's an electricity pole (two, actually) on our plot. They had been there for years. In September 2021 UK Power Networks approached us about replacing them (after talking to the previous owners of the plot), and then one day turned up on site and phoned me asking to be let in to do the works - bit tricky as I wasn't expecting them and I live 25 miles away. They got replaced, and moved slightly to our benefit.

 

Our planned sewage treatment plant will need to go quite near the pole. In fact, my other half had drawn up plans for the treatment plant to go slap-bang where the pole is, until I just noticed this! We have very few options where else the system can go (groundwater source protection zone one, root protection areas, rights-of-access, vehicular access, non-designated heritage asset...). We want to use Graf infiltration tunnels as they take up less space, and we've got a permit application open with the Environment Agency to this effect (non-standard infiltration solutions require one, and we're asking to discharge to ground in groundwater source protection zone one).

I need to send plans back to the EA by the end of Friday with the location of the infiltration tunnels on. I don't know where I can put them, without knowing what's allowed regarding electricity poles.

 

As an aside, I'm not aware of any wayleave existing. If it does, it's not with us. Any idea how I'd find out about such a thing?