R-3300A_CP4B_MergerMeetingSummary

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 1 of 7
Date: April 18, 2018
Time: 10:00-12:00 PM
Location: NCDOT Structure Design Conference Room Raleigh, NC
Purpose: R-3300A Hampstead Bypass from I-140 (Future) Wilmington Bypass to just
South of NC 210 in New Hanover and Pender Counties – Division Three
In Attendance
Name Organization Phone Email
Steve Bondor Dewberry 919-636-6334 [e-mail]
Crystal Moore Dewberry 919-424-3745 [e-mail]
Mark Staley NCDOT- REU 919-707-2948 [e-mail]
Cathy Brittingham DCM –Raleigh 919-707-9149 [e-mail]
Chris Rivenbark NCDOT-EAU 919-707-6152 [e-mail]
Paul Atkinson NCDOT Hydraulics 919-707-6707 [e-mail]
Matthew York NCDOT Hydraulics 919-707-6765 [e-mail]
Tyler Stanton NCDOT-EAU 919-707-6156 [e-mail]
Stephen Lane DCM 919-707-9224 [e-mail]
Brad Shaver USACE-Wilmington 910-251-4611 [e-mail]
Trace Howell NCDOT Division 3 910-341-2000 [e-mail]
Brian Lipscomb NCDOT-Hydraulics 919-707-6735 [e-mail]
Amber Coleman Stantec 919-865-7399 [e-mail]
Jason Elliott NCDOT-EAU 919-707-6114 [e-mail]
Mason Herndon NCDOT Division 3 910-341-2036 [e-mail]
Ricky Greene Stantec 919-865-7562 [e-mail]
Andrew Nottingham MI Engineering 919-851-6601
Ext 111
anottingham@mi-
engineers.com
Linda M. Johns MI Engineering 919-851-6606
Ext. 115
[e-mail]
Kevin Bowen ( on the phone) NCDOT Division 3 910-341-2000 [e-mail]
Travis Wilson (on the phone) NC WRC 919-707-0370 [e-mail]

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 2 of 7
Summary of Discussion
The R-3300A project is on new alignment, has a length of approximately 7 miles, and
includes one major interchange at I-140 (future) Wilmington Bypass. The project begins
at the north end of U-4751(Military Cutoff Road), which is currently under construction.
The typical section is a 4-lane divided highway with paved shoulders and median ditches.

The purpose of the meeting is to review and minimize potential impacts that the hydraulic
design may have on jurisdictional streams and wetlands. Dewberry has the southern half
of the project up to Sidbury Road and MI Engineering has the northern half of the project
starting at Sidbury Road.

General Comment:
• Wetland boundary and symbology scale changes throughout the plan sheets. It
is difficult to follow the wetland boundaries in some areas due to the larger
spacing of the wetland boundary line style and frequency of wetland symbols.
Furthermore, in many areas the wetland boundaries do not follow the contours.
Location and Surveys is working on this and will provide new files to Stantec.

Plan Sheet 4
• No Comment

Plan Sheet 5
• Consider eliminating portions of the lateral ditch left side Y33RPB to avoid ditch
through wetland. Consider use of cross pipes at existing ditches below Y33RPB
instead of lateral ditch
• At the box culvert at Y33RPA add tree planting details to the channel
realignment detail
• Cross section of the existing stream will serve as the template or guide for
construction of the channel

Plan Sheet 6
• Consider addition of cross pipe at –L- Sta 243+50 to divert flow to existing natural
channel on right and remove ditch through wetlands along L 251+00 to 253+00
left . Confirm box culvert size due to additional drainage area from cross pipe.

Plan Sheet 7
• Add Toe Protection to the fill slope L 255+50 to 258+00 RT within wetland.

Plan Sheet 8
• No Comments

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 3 of 7
Plan Sheet 9
• Add Toe Protection to the fill slope L Sta 284+00 to 285+50 LT within the
wetland.
• Discussed potential addition of sills to box culvert. However, after review of
photographs and dimension of existing channel, agreed that sills are not required.
Culverts will be backfilled with native material.

Plan Sheet 10
• No comments

Plan Sheet 11
• No Comments

Plan Sheet 12.
• No Comments

Plan Sheet 13
• Move pipe system 1301-1302 out of the wetland to L Sta 334+50 LT
• Remove riprap outlet protection at structure 1307

Plan Sheet 14 (Dewberry)
• Revise the 2’ Base ditch at –L- 347+50 RT to toe protection.
• Y34 Sta 20+00 to 21+00 right consider ending the 4’ base ditch at the wetland
limits. Transition from base ditch to existing grade with use of riprap pad at end to
eliminate a concentrated flow into the wetland.

Plan Sheet 14 (MI Engineering)
• USACE: The remnant triangle WLB at -L- Sta. 359+65, left side of the fill slope
should be a total take since there is no hydraulic connection to it.
• The “HP” symbol at -L- Sta 357+14.52 represents a crest in the roadway, which
is the dividing point between Dewberry and MI Engineering project limits.

Plan Sheet 15
• No Comments

Plan Sheet 16/17
• NCDOT Div 3: -L- Sta. 385+50, Left, rip rap channel that outlets to Waynes
Branch, which is a jurisdictional stream: Request was made to adjust the
alignment of the rip rap channel to include a curve from the pipe outlet that
provides a softer transition to Waynes Branch.
• Cross pipe at -L- Sta. 386+15: Does this pipe pick up stormwater? No this is a
cross pipe, which does not pick up roadway drainage. This crossing conveys a

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 4 of 7
jurisdictional stream with adjacent wetland boundaries. New surveys that are
expected to be completed soon will most likely reflect narrower jurisdictional
stream boundaries.
• USACE/NCDWR: Cross pipe at -L- Sta. 386+15: This jurisdictional stream was
deemed a high value system and was purposely avoided during 2B Merger
meeting. A commitment was made at the time to bridge this jurisdictional stream
with Waynes Branch. This location would be difficult to bridge since there is high
ground between this jurisdictional stream and Waynes Branch, which is located
near -L- Sta 386+00, Right. This jurisdictional stream is a low flow stream going
through a wetland.
• Additionally at the above location a request was made to remove the embedded
rip rap from the bottom of the outlet base ditch as well as softening the outlet
channel alignment. Rip rap will be retained on the channel side slopes to avoid
erosion and the channel will stop short of Waynes Branch as much as possible.
• NCDWR: Is there enough room under the bridge to allow for end bent slope
protection and wildlife passage? There is 15’ provided from the overflow channel
(left channel) to the slope protection. NCWRC thinks there is enough room.
• NCDWR: For the lateral V ditch coming from the pipe located at approximately
St 377+80: Why can’t the riprap be pulled back onto high ground and allowed to
sheet flow to Wayne’s Branch? If the proposed pipe could be placed at the fill
slope and natural ground elevation, the proposed pipe would be at a 1.0% slope.
The ground just west of the pipe outlet is higher along the projected path of outlet
flow, and lower ground exists at the toe of slope protection at -L- Sta 385+43, 98’
Lt. If no riprap protection is provided two things would most likely occur:
o The drainage area for this crossing is approximately 22.5acres and the
Q10=46cfs including future development. The velocity for the 10year
event is approximately 6.9fps, which would cut through the natural ground
to the west. There would eventually be a new outfall path created
downstream of this pipe outlet, created by erosion.
o Existing drainage patterns would also erode the banks of the old
jurisdictional stream location at -L- Sta 385+43, 98’ Lt. for the lower storm
events.

Plan Sheet 18
• No Comments

Plan Sheet 19
• USACE: Do we need a riprap pad at the outlet at -L- Sta. 415+15 Lt.? This is
the outfall for some roadway drainage and a riprap pad is most likely warranted.

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 5 of 7
Plan Sheet 20
• USACE: There is a wetland located at 436+50 Rt., but there isn’t a cross pipe. A
ditch is proposed just outside the existing wetland boundary at 436+34 Rt. to
allow relief from this wetland once it heads up, in lieu of a cross pipe.
• -L- Sta. 434+18 Lt: Updated surveys are expected to provide better coverage of
the jurisdictional stream.

Plan Sheet 21
• NCDWR: General comment: Add typical notes to ensure the culvert is backfilled
with native bed material.
• NCDWR: Provide floodplain bench to be added to both sides of the pipe.
2@6’X7’ RCBC are proposed with a 1’ sills and baffles in the north barrel to
create a low flow channel and 2’ sills in the south barrel to create a floodplain
bench in the other barrel.
• USACE: Does this system show significant signs of overbank flooding? Would
this location benefit from a proposed floodplain pipe at this crossing? The
wetland boundaries are very close to the existing jurisdictional stream. The
floodplain is not wide enough on the upstream side to provide one.
• USACE: 448+20 Lt & Rt: Is there a connection between the wetland left and the
right side of the proposed roadway? There is a connection, and a pipe can be
added however, the surface drainage runs from the northeast to the southwest.
Most of this surface drainage incorporated with the wetland on the left side of the
roadway runs parallel to the fill slope. Lateral connectivity appears questionable.
Drainage is acceptable as shown.

Plan Sheet 22
• USACE: Cross pipes at -L- Sta. 452+55 & -L- Sta. 455+06: Why do we need rip
rap pads at these cross-pipe outlets if we are connecting wetland boundaries? If
these pipes behave as an equalizer pipes, and velocities do not warrant rip rap
pads, they will be removed.
• USACE: Large wetland at -L- Sta. 460+00 Lt: How does the large wetland
maintain connectivity? Connectivity will be provided by the proposed cross pipes
at -L- Sta. 455+06 and -L- Sta. 461+50.

Plan Sheet 23
• NCDWR: How deep is the Special Lateral V ditch located at -L- Sta. 467+70 to
471+50 Lt? The Special Lateral V ditch will be eliminated in the wetland and toe
protection will be provided as needed at fill slope/wetland boundaries.

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 6 of 7
Plan Sheet 24
• USACE: Provide “Do not Bury” labels in the final plans for equalizer pipes.
Pipes for wetland connectivity can either be labeled as “Equalizer Pipe” or “Do
not bury”.
• NCDWR: What is to be graded to drain between the NW CA fence and fill slope
at about 479+00? This is an attempt to eliminate a shallow ponded area at the fill
slope. Since it is within the wetland, Grade to Drain will most likely be removed
and replaced with Toe Protection at the fill slope, if warranted.

Plan Sheet 25
• No Comments

Plan Sheet 26
• No Comments

Plan Sheet 27
• Why is there rip rap in the middle of the channel? This rip rap represents the
side of the floodplain bench. The northwestern channel is the low flow channel
and the south-eastern channel is the floodplain bench.
• USACE/NCDWR: Is it possible to adjust the alignment of the proposed 2@7’x8’
RCBC to eliminate the abrupt angle of the channel at the upstream end of this
RCBC? Consideration was given to start the RCBC near 521+00 Rt, route it
north and west of the proposed interior bent of the Y35 bridge. If the new
alignment were used, the RCBC would be much longer due to the fill slope of
Y35 and the outlet transition would not eliminate the severe angle, but just move
it to the outlet side. It was agreed that a smoother transition could be
incorporated at the upstream end of the culvert.
• -L- Sta. 524+25 Lt: Updated survey at the downstream end of the proposed
culvert should reflect a smaller width for the jurisdictional stream. Consideration
will be given to reducing the amount of rip rap at the downstream end of the
RCBC and channel change after the tangent section is achieved.
• NCDWR: General comment: Add typical notes to ensure the culvert is backfilled
with native bed material.

Plan Sheet 28
• No Comments

Plan Sheet 29
• NCDWR: Is the pipe at -L- Sta. 546+00 an equalizer pipe? There is a ditch at
the left side that is being conveyed to the right.

DRAFT R-3300A 4B MEETING HYDRAULIC DESIGN REVIEW
R-3300A CP 4B Meeting Minutes 7 of 7
Plan Sheet 30/31
• NCDWR: Provide sills and floodplain bench at Harrison Creek Tributary CSR
3@12’x8’.
• NCDWR: Provide label about backfill culvert with native bed material.

Plan Sheet 32
• No comment

Plan Sheet 33
• No comment

Plan Sheet 34
• No comment

Plan Sheet 35
• The 18” RCP-IV under SR1 is not an equalizer pipe

Plan Sheet 36
• No comment

Plan Sheet 37
• Review north arrow orientation and correct as necessary

Plan Sheet 38
• No Comments

Plan Sheet 39
• No Comments

It was noted that geotechnical ditch and right of way recommendations have just been
developed to account for high groundwater tables in shallow fill areas. The design team will
meet on April 19th to evaluate any impact these recommendations will have on the proposed
hydraulic design. If wetland areas will be affected by these recommendations the preference is
to raise the profile grade (increase fill depths) as opposed to possibly placing ditches in wetland
areas to keep the fill section drained for stability.

With no other matters to discuss the meeting was adjourned.