Before I make a fool of myself, by having any sort of opinion I would like to ask what is the eventual aim of the re-purposing of the property? Also, in image 1101 there appears to be some sort of ledge. Has this been inspected for damage under the ledge?

Thanks for the reply. The property was formerly an operating textile mill until 2008 when the company shut down due overseas competition. The property now consists of 13 buildings in various states of restoration with 40+ businesses as tenants.

It's my understanding that the ledge in that picture was some sort of poured concrete slope to transition to the granite wall when it was constructed approximately 5 years ago.

This is only a guess but it appears the concrete many have been undercut by the flowing water. You can see the leading edge is badly crumbled at at least one point. Another possibility is that the weight of it could have forced an existing stone out of place or that there was already some damage to the wall that was not repaired before the pour. A fourth possibility is that the composition of the mortar and concrete is not compatible and did not properly seal. This could be for many reasons such as oil on the surface of the mortar or even a layer of algae. One last possibility that the problem lies there might be that a damaged area of mortar was repaired but not cured before water flowed against it. That could cause a fairly rapid erosion of the mortar in that area while not affecting other areas.

I can't see the top edge of the cement where it joins the wall due to the shadow so these ideas could easily be totally without foundation but I would check out the ledge before I spent any large amount of money. What is the bottom made of?

Interesting, the wall was built on a 3' deep footings, so I don't believe the concrete slope you see is functional other than to minimize erosion. The bottom of the sluiceway is earthen, and before the current wall there was simply an embankment with riprap which I believe was in place going back into the early 1800's.

Looking at the photos again, especially the Google overhead shot and that made me wonder a few things like when the parking lot was last worked on( I assume there is a large expansion joint between the wall and the parking lot) or if there has been a large snow plow used in it. Don't know how careful a snow plow can be in some conditions. I know one stripped the facade off of a jutting support at our house and cracked the concrete support by backing into it. Bent reinforcing rods but only scratched the paint on the plow.

What is odd is the water flowing onto the parking lot at the northeast(?) side of the lot. Where is that water coming from? Is it coming from under the parking lot or alongside the parking lot? Digging down at that side where the parking lot meets the wall could give you a better idea of what is going on since you would be moving only dirt, not stone, masonry or concrete. Just follow the wet stuff. For some reason this makes me think the problem may have come from the parking lot side rather than the inside of the sluice.

Once again this is pure supposition from what I can see in the pictures. All I have is questions.