Industrial unit box gutters in roof valleys

Hi chaps,

ive been asked to quote to clear the roof valley gutters on some industrial warehouse units.  They need doing as a one-off and then customer wants them maintaining every 2-3 months...They have a H&S officer on site, and am a safety conscious person so want to make sure everything is safe for me to proceed with the work.  Ive got the camera up there and there is standing water in the valleys (cant see much else) and debris collected around the downpipes. 

My method would be to access the roof at a safe place with secured ladders, shift all the muck to the downpipe end of the valleys and have a second operator to vac it up from the ground.

Use roof ladder to assend and decend the roof at the apex and repeat.

For areas inaccessible to vac, bucket and trowel it to an accessible place and vac the bucket out.

A couple of questions:

How can you tell if the valleys can be walked on?

Has anyone got any thoughts on the above, or experience of similar?  

Do i need any qualifications to be working on the roof in the first place?

Ive thought about scaffold towers / platforms etc, but someone still needs to walk along the vallys to clear them...

I also need to quote for their office buildings which can be done with the vac, so dont want to pass on the industrial units as will likely losethem both...

Thanks in advance!

We have done some like this in the past usually use a scaffold tower and depending how deep the roof is pull the dirt towards us using a Harris pole and applicator or use the gutter vac poles without an end on to suck it up as we clear depends how bad they are and how deep the building is , part timer does some jobs like this I think he might have some ideas that may help as well , personally I wouldn’t get on the roof , as a last resort if there was nothing else ide use crawling boards but preferably a cherry picker but this will obviously add to the cost 

Unless their H&S states it's safe to walk on and has them checked regularly I wouldn't put a foot on it, let alone walk on them. 

Scaffold tower, adapted WFP and scrape, push rubbish to the end and put in bucket. 

Part Timer said:

Unless their H&S states it's safe to walk on and has them checked regularly I wouldn't put a foot on it, let alone walk on them. 

Scaffold tower, adapted WFP and scrape, push rubbish to the end and put in bucket. 

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ok, but what about the valleys you cant get to becase of other buildings in the way?  or do you just set the tower as close as possible and do what you can?

It's very hard to give exact advice on one photo, if you're talking about the building in front of your van then yes. We've got no concept of the length the valleys are, or if you have access the other side. I said adapted WFP because with an acme thread you can put pro gutter tools and reach as far as your longest pole. So in my case, if access from both sides I can reach 100 feet. Or as @Pjjsaid use your gutter vac.  

Gutter vac only. I know a lad who went through one of these roofs and fell into a hot vat of boiling water, spent six months in hospital with terrible burns scarred for life and only just survived. You are right to play safe. There will be someone near you with a gutter vac if you haven't got one. Wise to play safe on these types of roofs.

All the best and make it pay.

Can you check the valley round the bit you cant see with gopro camera or gutter camera to see how bad it is? Might not need any work.

That's where a camera drone comes in handy even if you have to visit a club or shop and see if they can do a survey.