Attachment C_USS_NC_Hyd Review 03 09 2021

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STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
Roy COOPER
GOVERNOR
COUNTY:
MEMORANDUM TO:
FROM:
SUBJECT:
J. ERIC BOYETTE
SECRETARY
March 9, 2021
New Hanover
Robert Vause, PE
Division Maintenance Engineer
Division 4
Galen Cail, PE
Manager Hydraulics Maintenance East
Review of Resurfacing along USS North Carolina Road
Pursuant to your request a hydraulics review has been prepared. A request was made on
December 31, 2020 to review resurfacing along USS North Carolina Road. The road is
the main access to the USS North Carolina Memorial. Our review also included
consideration of planned USS North Carolina Memorial site improvements. There are no
specific site plans prepared at this time, but we did review the report prepared by the
USACE in January 2017. Site survey data provided by the USS North Carolina was also
reviewed. Below is a summary or our investigation.
A meeting was held onsite on January 20, 2021. Present at the meeting was myself,
Robert Vause, Kathy Stephens and Trey Moore of the Division and Chris Vargo,
Assistant Director of the Battleship North Carolina Memorial. At the onsite meeting
there was discussion about the flooding history and frequency around the USS North
Carolina property as well as along USS North Carolina Road. There was discussion of
historical flooding as well as the observed tidal influence/flooding on a typical daily basis
that has been observed to increase in frequency over the years. Mr. Vargo noted there
have been instances where visitors to the memorial have had difficulty leaving along USS
North Carolina Road due to flooding. Mr. Vargo also acknowledged there are flooding
issues on the USS North Carolina property as well that have been or are being addressed
through investigations/proposed plan improvements on the property. The US Army Corp
of Engineers provided an investigation in January 2017. This investigation provided
possible options and preliminary analysis for potential stormwater improvements on the
property. Also, the memorial presently has a consultant firm contracted to investigate
stormwater improvements. This study is still ongoing.
Mailing Address: Telephone: [phone] Location:
NC DEPARTMENT OF TRANSPORTATION Fax: [phone] BIRCH RIDGE DRIVE
HYDRAULICS UNIT Customer Service: 1-877-368-4968 RALEIGH, NC 27610
1590 MAIL SERVICE CENTER
RALEIGH, NC 27699-1590 Website: www.ncdot.gov

While onsite we walked USS North Caroline Road starting from just east of the parking
lot at the curve and continued to the west to the Cape Fear River. Mr. Vargo noted the
low side of the road at the curve is especially susceptible to tidal influence/flooding. Just
east of the curve he also noted it is not unusual for the road to overtop. This location
looked to be the sag of the road in this vicinity. In this vicinity the existing ditch -line
water was also observed draining "into the ground" at 2 locations north of the road. One
was just west of the westernmost parking lot entrance and the other approximately 250
feet further west. A pipe was not observed at either location. Further
investigation/excavation would be needed to determine if there are existing drainage
features/structures at these locations. A significant portion of ditch -line along USS North
Carolina Road was observed to be shallow, highly vegetated and undefined until you get
closer to Battleground Road NE. Existing drainage features were observed north and
south of USS North Carolina Road. A system of culverts and inlets was observed/located
in the swale/ditch-line just north of the road that drained east into the Cape Fear River.
This system looked to continue to the west but could not be physically observed or
located due to submergence. On the south side of the road were a series of driveway
pipes and a cross pipe under Battleground Road NE that also drained east to the river.
As part of our review, we also gathered existing documents/plans from NCDOT and USS
North Carolina Memorial sources and the US Army Corps of Engineers. Some of these
plans verify the drainage features observed as well as indicate additional existing
drainage features further west along USS North Carolina Road. Our review also included
generating lidar contours and incorporating aerials. Streetview photos were also
reviewed. Elevations of typical tidal flooding were estimated using lidar and recent video
footage of the road overtopping. The estimated elevation of typical tidal flooding was
projected and relative locations of impacts were mapped. Based on our investigation the
estimated tidal flooding was elevation 3.1 feet. The estimated roadway overtopping
elevation noted along USS North Carolina Road is elevation 2.9 feet. Other notable
elevations at or below elevation 3.1 feet are at the driveway entrances to the memorial.
and along Battleship Road NE. It should also be noted that per lidar contours the
elevations around the USS North Carolina Road and US 74/421 intersection are
approximately 4.0 feet on the US 74/421 travel lanes and 3.5 feet on the entrance turn
lanes. Elevations in the curve along USS North Carolina Road, where the flooding was
noted by Mr. Vargo, is approximate elevation 2.0 feet on the low side of the travel lane.
Our estimated flooding and roadway elevations are consistent with those noted in the US
Army Corp of Engineer's study. Lidar used in our investigation is per datum NAVD88.
Based on our investigation the adjustment of road grades due to resurfacing or
improvements to road LOS, along USS North Carolina Road and Battleship Road NE,
would be relative to two different considerations. Moderate/high risk and low risk. We
would consider raising of the low side travel lane in the curve along USS North Carolina
Road to be low risk. This area does not impact the road sag or road overtopping and
should have negligible impact to backwater. We would consider raising of road grade
sags to be moderate to high risk depending on efforts necessary to improve/reestablish
existing drainage in the area and pending extent of site improvements on the USS North
Carolina Memorial property. At this time, without any drainage improvements along
USS North Carolina Road, if the road sag were to be raised, we would anticipate some
backwater impact and potential moderate risk to memorial facilities with increased

overtopping frequency of the driveway entrances to the memorial. We would consider
raising this road grade to be low to moderate risk for the US 74/421 turn lanes
considering other facilities (memorial driveways) would overtop prior to this impact. All
risks would be dependent on how much the road grade/LOS was improved and the extent
of improvement to drainage systems along USS North Carolina Road and Battleship
Road NE.
We would recommend the low side of the travel lane in the curve be raised to reduce road
flooding. Prior to any additional improvements to road grades we recommend further
investigation into potential existing drainage features along USS North Carolina Road or
on USS North Carolina Memorial property. Site observations and review of older and
contemporary plans indicate there are additional drainage features in this area. Since
some of these features could be located both inside and outside of NCDOT R/W we
would anticipate investigation and potential remediation to require a cooperative effort
between the Department and the USS North Carolina Memorial. Pending the
investigations, further drainage review and improvements may be necessary including
pipe system and ditch cleanout or repair/replacement. The extent of improvement would
influence the level of risk due to resurfacing or raising the road grades. We would also
recommend that the memorial improvement plans, once available, be provided to the
Department for review to better assess and manage overall risks to the road(s) and
memorial property.
If additional information is needed please contact this office.
WGC
CC: Kathy Stephens
Trey Moore
Attached: Lidar/Contour mapping