20010550 Ver 7_Email_20081006

Re Construction issue on R-2809A (Wake Forest Bypass)
Subject Re Construction issue on R-2809A (Wake Forest Bypass)
From Rob Ridings <rob ridings@ncmail net>
Date Mon, 06 Oct 2008 10 40 57 -0400
To "Murray, Christopher A" <cmurray@ncdot gov>
Chris,
This sounds like a good solution to me I'll support it
-Rob
Murray, Christopher A wrote
Eric and Rob,
o/ O 5?d
A) C
The Department is currently planning construction work at Stream Permit Site No 1 near 9+10 Lt -L-
Construction at the site involves extension of a corrugated metal pipe structure only at the downstream
pipe section A construction issue has come up at this site which is addressed below
Issue
Construction involves extension of a metal pipe structure and installation of 26 linear feet of rip rap
on the streambank below the pipe structure A site investigation earlier this week revealed a small
mass of rock and tree root which is serving as an unstable grade control feature approximately 5 to 10
linear feet downstream of the lower part of the pipe extension There is approximately a 1 5 to 2 0
foot change in elevation of the stream bed at the grade control structure
We are concerned about the stability of the grade control feature, it will likely fail during
installation of the pipe structure or installation of the 26 linear feet of rip rap below the pipe
structure If it falls, the stream will headcut (due to the streambed elevation change) up to the pipe
outlet The pipe will then be perched
We propose to install the invert of the pipe structure based on the streambed elevation below the grade
control feature We are aware that this is not the typical construction scenario However, it appears
appropriate based on the existing on-site features
Permitting
This proposed construction scenario will not result in additional impacts to streams, wetlands or
riparian buffers
The attached drawing roughly depicts the existing scenario
assessment and plan at the site
Thanks
Chris Murray
Please let me know if you agree with our
1 of 2 10/6/2008 10 41 AM
Re Construction issue on R-2809A (Wake Forest Bypass)
P? ?i?,e? down 5tre q.,, took
1t,-4 oar p;pe S+(VtArrr ktte
n "N
Sk{e.?... De.?` caul rOA k j Q\
E-? a? S c r
r•4 &t ? ?? r?Qt'?' ?[af ox J? d. 9..w S'lYC q..,.
OA ?firea.. bMk,
Q IAU ?
P i') e- It)
CA J? V 4-
2 of 2
.,\ snt-ll
eV,,. 4 A
Si f e- G,.,
? Ir
tic, 4'( 0 "'t 6 Q ? 0 tral
cvAkt 0 ? eo i vrc-
10/6/2008 10 41 AM