20131282_Meeting Minutes_20110622

Subject:
Team Members:
Minutes from Interagency Hydraulic Design Review Meeting
on .luly 20, 2011 for R-3620 in Washington County
Bill Biddlecome- USACE
Gary Jordan- USFWS
Travis Wilson-NCWRC
David Wainwright- NCDWQ
Chris Militscher-EPA
Cathy Brittingham-DCM
Ron Lucas-FHWA
Elizabeth Lusk-NCDOT-NEU
Charles Cox-PDEA
Bob Capehart-Division 1
GENERAL NOTES:
(present)
(present)
(present)
(present)
(present)
(present)
(present)
(present)
(present)
(absent)
Participants:
Galen Cail, NCDOT Hydraulics
Larry Clawson; NCDOT Hydraulics
Gary Covering, NCDOT Roadway
Rick DeCola, NCDOT Roadway
Chris Rivenbark, NCDOT NEU
Chris Manley, NCDOT NEU
Mark Staley, NCDOT REU
Steve Kite, NCDO'f WL1'C
Nadia Aboulhosn, NCDOT PDEA
Thomas Stoddard, NCDOT STIP
There was discussion on side slopes in wetlands throughout the project. Some areas thru
wetlands are presently proposed with 4:1 without guardrail (versus 3: i with guardrail). It
is understood this is not a typical scenario and is unique to a 2 lane facility. However, we
wanted to propose for evaluation pending all the other factors considered including fill
height, safety, quality of wetlands, additional impacts, stormwater treatment, etc. Below
are a few advantages based on Hydraulics and Roadway perspectives.
From a hydraulics perspective the 4:1 grassed slopes can provide better infiltration if the
road superelevation requires shoulder berm gutter (SBG). The use of SBG is typically
proposed where 2 or more lanes flow toward the low side of the road and particularly
where fill heights are 5' or greater. This is used to minimize potential erosion on slopes.
With SBG stormwater will be concentrated and discharged at an outlet point whereas
without SBG stormwater will be able to spread out over grassed shoulders.
From a roadway perspective guardrail can be an obstacle and potential safety hazard.
especially on a 21ane facility where shoulder widths are at a minimum. Guardrail is
designed to deflect traffic, not stop it, and on narrow facilities has the potential to deflect
vehicles into oncoming traffic. A 4:1 provides a wider area for recovery. The use of
guardrail with minimum shoulders also limits the available area needed for broken down
or abandoned vehicles. There is also the issue of guardrail cost and maintenance.

There are 3 significant wetland areas along the project where this would have the greatest
effect. Below are locations of each and the associated additional impacts with 4:1 side
slopes:
Sta 12+00 to 44+80 -L- -- 0.25 acre increase (avg 1.6' width per side over 3280`)
Sta 90+00 to 119+00 -L- -- 0.26 acre increase (avg 2.0' width per side over 2900')
Sta 148+00 to 158+00 -L- -- 0.14 acre increase (eliminated, see note below)
Through these larger wetland areas the use of 4:1 side slopes results in approximately
0.51 acres of additional fill in wetlands over a stretch of 1.2 miles.
Note: Since the review meeting 3:1 slopes with guardrail is provided through entire
wetland Sta 148+00 to 158+00. See below "Sheets 13 & 14".
Sheet 4:
-It was discussed whether ditches could be used in wetlands if there is an existing ditch,
as long as bottom of ditch elevation is maintained or more shallow. Response was that
need to avoid to extent practical and use only if necessary with specific site justification.
Sheet 11:
There was discussion on the validity of some of the straight, wetland boundaries.
Sheets 13 & :4:
Around the proposed 1 ~ 12' X 7' box culvert 3:1 slopes with guardrail are proposed.
Note: Since the review meeting 3:1 slopes with guardrail is provided through entire
wetland (from approx. Sta 148+00 to 158+00). This will require SBG but plan to tie into
inlets at proposed 36" equalizer pipes. This will allow energy dissipation of stcrmwater
in the inlet versus at an outlet. It was also stated that this may be one of the higher quality
wetlands on the project.
Sheet 15 & 16:
-It was discussed that stormwater storage/treatment will be investigated in the areas where
the existing road will be abandoned and removed.
Meeting adjourned