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Ryan,
I received the monitoring report last night for this week from Endemic and wanted to ask about the swales. I was not aware that the project was going to be constructing cement v-ditches.
I’ve got a copy of three of the pages of the trail design overview and they only note that there would be cobble swales installed, which suggests to me a shallow ditch filled with rocks
to slow water flow down. I don’t have any of the actual detail pages that presumably note that these swales are actually concrete, not cobble. Dick’s email from November 7, where he
addressed some of the drainage questions from Robin Smith, noted that the cobbles swales will “have ‘natural-appearing’ rock cobble to lend a more natural look to this drainage improvement.
Although smaller in size, the inlaid cobble is the same color/texture as the rock fill for the Gabion Wall components.” The photo below does not look natural at all, it looks completely
manufactured, has very little rock actually in it, and as I noted above, is concrete, not cobble. I’ve looked at the design overview plans and see that there are several more of these
located throughout the trail, including one on the western end very close to the drainage.
I emailed the photo to my coworker who has a regulatory background and asked him if this was going to be a problem with the fact that I’ve been telling Fritz Rieman at CDFW that the
project has no potential to affect any local waterways. He noted that without any sort of splash pad or “velocity reducer” as it’s noted in the design plans, this would in effect just
funnel water straight onto the trail and potentially cause more erosion, and depending on the possibility of sending sediment downstream to the drainage, could be an avenue where Fritz
says a permit would be needed. I see in the plans that the velocity reducers are planned but just don’t see it in this photo yet.
Since this design is news to me, I guess my immediate question is if this is what it’s supposed to look like. The design plans say “cobble swale” and Dick’s email said the features will
have “natural-appearing” cobble, neither of which describes the photo above. Is there going to be actual rock put into this? I’m obviously not an engineer, but to me this doesn’t look
like it would be too effective as-is with reducing flow, especially in strong rains.
This isn’t an emergency but right now more of a clarification to make sure I understand what the project is putting in, especially with any coordination and conversation that I have
to send to Fritz in the meantime while you’re out.
Thanks and Happy Thanksgiving!
Ryan Winkleman | Project Manager/Senior Biologist/Certified Senior Ecologist
5 Hutton Centre Drive, Suite 500 | Santa Ana, CA 92707 | [O] 949-330-4115 | [M] (949) 533-0918
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