20050861 Ver 2_Staff Comments_20061205

comments on OS-0861 Snow Creek Stream Restoration
Subject: comments on OS-0861 Snow Creek Stream Restoration
From: Larry Eaton <[e-mail]>
Date: Tue, OS Dec 2006 08:22:17 -0500
To: Ian McMillan <[e-mail]>
I got a chance to look at this restoration plan last night. Its pretty short on
details. Details like just how big it is. It looks like its around 2000 ft of
stream, but the only number I could find was a 10 foot crossing on an intermittent
stream. There was also no discussion about pre or post construction monitoring of
any kind, there better be some. I was also a bit concerned about some of the
Hec-Raz numbers. First the top of the stream was designed to be a B stream and a C
stream was used as a reference. Considering one is alluvial and one is coluvial,
thats a totally different kind of stream and that reference is inappropriate. I was
also a little concerned that section after section, the stream bankful crossectional
area of the proposed reach was significantly (20-50~) larger than the reference
reach. If I remember my Rosgen correctly, thats an invitation for sediment not to
move through the system, but to settle out in the project. There were additional
inconsistencies between proposed reached and reference reaches, but I will leave it
to an engineer to decide if overlong riffles and glides are a problem.
Overall this might not be a bad project, but there is not enough information to
know.
Larry
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