@Bamboo I migrated it because it's not about gardening; it's about repairing a physical structure which happens to be outside of someone's house. If you look at the photograph, there is clearly concrete on both sides of the drain.

Given that, it's natural to assume that it's not in a garden (in the "where things grow" sense of the word).

@NiallC. Well, yes, but now you know it IS in a garden, and that it is a feature of landscaping, shoudn't it really be in the Gardening & Landscaping section? Were I the person who posted the question, I'd certainly have posted it there because it says 'landscaping', and it's not a Home Repair. I've ordered and installed more ACO type drains than I care to think about in my years as a 'scaper...

@NiallC. Either way, it probably doesn't matter now, but I feel sorry for anyone with a landscaping question that doesn't involve soil or plants, cos they'd be a bit stuck as to where they put their question...