architects disagree on necessity of civil engineering services...

[Chris Morris]

Architect A estimated I would need to pay $10K-$15K for civil engineering services for a 2 story ADU on a flat lot in Los Angeles.

They say it is for grading and low impact development/stormwater management).

Architect B thinks the civil engineering services could possibly be avoided entirely:

"Grading shouldnt be significant and not need design work.

FYI: Your property is in a special zone that requires extra hoops to jump through for grading, but I have only seen that triggered when excavating for a basement parking level. This would be an item that goes wrong, but is not anticipated.

LID/Stormwater can be covered by the architect/client with some simple notes and provisions for the project."

Any thoughts? Who is closer to the truth? 

Also, Architect B, if you see this post, no disrespect. I don't have experience in this area and am reaching out for more opinions. :-)

[Matt Devincenzo]

Both can be correct. I talk clients out of using me for site civil on projects all the time...but that exact same project with a different architect I'd absolutely suggest they use my services.

The response you received from architect B is predicated on them being comfortable doing that scope which is 100% feasible. But another architect may not have sufficient experience with the requirements generally, or maybe just in that jurisdiction. Either of those reasons would mean them covering that scope either delays the project or drives up design cost because it's outside their wheelhouse. So both are correct...you have to understand each scope and why/how you're choosing your team to get to your end result.