20200064 Ver 1_NC 615 Shoreline Stabilization Field investigation Report final - Copy_20191210

DIVISION OF COASTAL MANAGEMENT
FIELD INVESTIGATION REPORT
APPLICANT'S NAME: North Carolina Department of Transportation (NCDOT)
2. LOCATION OF PROJECT SITE: Roadway Shoulder/Shoreline Stabilization on NC 615,
(Marsh Causeway) in Knotts Island, Currituck County.
Latitude: 36' 32' 30.4152" N Longitude: 75' 58' 33.2364" W (Project Start)
Latitude: 36' 32' 11.6772" N Longitude: 75' 55' 53.8248" W (Project Stop)
3. INVESTIGATION TYPE: CAMA and D&F
4. INVESTIGATIVE PROCEDURE: Date of Site Visit — November 13, 2019
Was Applicant Present — No
5. PROCESSING PROCEDURE: Application Received Complete: November 4, 2019
Office — Elizabeth City
6. SITE DESCRIPTION:
(A) Local Land Use Plan — Currituck County
Land Classification from LUP — Conservation
(B) AEC(s) Involved: CW, EW, ES, PTA
(C) Water Dependent: Yes
(D) Intended Use: Public
(E) Wastewater Treatment: Existing — N/A
Planned — N/A
(F) Type of Structures: Existing — Two-lane road for public use
Planned — Two-lane road for public use
(G) Estimated Annual Rate of Erosion: 3'-4'from wave action
Source — Applicant
HABITAT DESCRIPTION: [AREA]
EXCAVATED FILLED OTHER
7.
(A) Open Water
39,681 sq. ft.
(B) Coastal Wetlands
380 sq. ft.
(C)Upland
890 sq. ft.
(D) 56, 062 sq. ft.
No
SC (Back Bay)
Total Area Disturbed:
(E)
Primary Nursery Area:
(F)
Water Classification:
Open: No

FIELD INVESTIGATION REPORT:
NCDOT — CURRITUCK COUNTY
NC 615 ROAD SHOULDER/SHORELINE STABILIZATION PROJECT
PROJECT SUMMARY: The applicant proposes to protect the roadway
shoulder/shoreline along NC 615, Marsh Causeway, (aka Knotts Island Causeway)
within the MacKay Island National Wildlife Refuge with approximately 9,405' of new
rip rap revetment and the maintenance/repair of approximately 1,766' of existing rip
rap revetments adjacent to Back Bay and the man made borrow canal near the of
community of Knotts Island, Currituck County.
8. NARRATIVE DESCRIPTION:
Project Setting
NC 615 (Marsh Causeway) connects the community of Knotts Island, NC to mainland
Virginia and ultimately provides a vehicular connection to NC 168 within Currituck County. The
Knotts Island community consists of single-family residences with NC 615 being the only roadway
access to the mainland and provides access to the Knotts Island Ferry Terminal that is located at the
southern end of the roadway. NC 615 is a paved two-lane road with 10' travel lanes and no paved
shoulders. The current project has multiple existing culvert pipes along NC 615 in the project area).
Grass shoulders on the roadway range from approximately 1'to 10' wide. A roadside manmade
borrow canal is adjacent to the north side of the roadway, with areas of existing stabilization
revetments along portions of the canal bank. The project area is also on the southern edge of Back
Bay, which includes areas of existing stabilization revetments along portions of the shoreline. Back
Bay and the roadside canal are navigable in the proposed project vicinity. The roadside borrow
canal ranges from approximately 25'to 85' in width and approximately 1' to 5' in depth.
The roadway transects a coastal marsh dominated by Juncus roemerianus (Black Needlerush),
Typha (cattails), Spartina cynosuroides (giant cordgrass) and Phragmites australis. The entire
project is within Mackay Island National Wildlife Refuge. The refuge is approximately 8,219 acres
and is popular for bird watching, bicycling, photography, fishing, and kayaking. Mackay Island is an
important wintering area for thousands of ducks, geese, and swan. There is one auto tour route and
two hiking and bicycling trails that provide access to the refuge, as well as 20 miles of canals that
wind through the swamp -like habitat. A refuge -maintained wildlife viewing area is located within
the project area with ingress/egress access via NC 615.
There are no stormwater runoff controls on the road. Stormwater sheet flows directly into the
adjacent roadside canal or marsh from the road. An aerial power line and telecommunication line
are within the Right -of -Way on the north side of the roadway, with no existing utilities on the south
side of the roadway. There are no known historic or archaeological resources in the project area.
2

FIELD INVESTIGATION REPORT:
NCDOT — CURRITUCK COUNTY
NC 615 ROAD SHOULDER/SHORELINE STABILIZATION PROJECT
The Environmental Management Commission has classified Back Bay as Class SC in the
proposed project area. The North Carolina Division of Marine Fisheries has classified Back Bay in
the proposed area as Joint Waters and not Primary Nursery Area and/or an anadromous fish
spawning area. The waters are closed to shellfishing by the Shellfish Sanitation Section of the
Division of Marine Fisheries. Submerged aquatic vegetation was not observed at the roadside canal
shoreline or shoreline of Back Bay. The Federal Emergency Management Agency has designated the
project area as a Zone AE flood hazard area.
Due to erosion, sections of the roadside canal shoreline have been previously stabilized with
riprap. The applicant estimates the erosion rate on the shoreline to be 3'-4' from wave action in the
preceding 12 months in the project area. Between February 2008 and September 2019, the Division
of Coastal Management (DCM) issued ten (10) General Permits to NCDOT for shoreline
stabilization/emergency shoreline stabilization along different sections of Bells Island Road in the
project area. In addition, CAMA Major Permit 132-04 authorized the replacement of the bridge over
Corey's Ditch, including the replacement of two existing culverts and the installation of six new
culverts along NC 615 (TIP No. B-3445).
Project Proposal
Due to continued erosion of the shoreline, NCDOT proposes to protect approximately 9,405'
of shoreline along the northern shoulder of NC 615 with class II riprap and repair/maintain
approximately 1,766 of exiting revetment adjacent to Back Bay and the manmade borrow canal in
the project area. The applicant states the purpose of this project is to stabilize an eroding road
shoulder and maintain a minimum 4' wide shoulder. The applicant states that it wishes to obtain
authorization to address the erosion problems in their entirety along the causeway under one permit
with a longer authorization time period for funding and construction.
A total of approximately 9,405' new rip rap revetment is proposed, with approximately 8,643'
of the new revetment along the adjacent manmade borrow canal. The revetment would have an
average width of 8'waterward of the NWL and would not exceed 10' waterward of NWL when
protecting an upland road shoulder. A marsh toe revetment is proposed in two areas (both sections
totaling approximately 704') where Coastal Wetland marsh fringe exists adjacent to the road
shoulder along Back Bay. The proposed marsh toe revetment and will have a height not to exceed 1'
above NWL/marsh substrate and the toe of the revetment will not exceed 6' below NWL.
Replacing existing culverts is not part of the proposed project and the applicant states existing
riprap will be refurbished as needed with additional riprap around existing culverts. The riprap slope
will not change at the existing pipe location and will match the slope of the adjacent bank
stabilization.
Placement of revetment material will be completed using a tracked excavator and rubber tire
backhoe. The applicant states matting will be utilized during the placement of revetment material
that cannot be reached from the existing roadway. A small tracked loader and tracked excavator on
mats would be utilized with all revetment material contained in steel boxes. According to the
applicant, the location and extent of the wetland matting is unknown at this time and will depend
c

FIELD INVESTIGATION REPORT:
NCDOT — CURRITUCK COUNTY
NC 615 ROAD SHOULDER/SHORELINE STABILIZATION PROJECT
upon the equipment limitations (excavator reach) of the contractor hired to do the marsh toe
revetment. The applicant states approximately 890 sq. ft. of backfill would be required for the
existing roadway shoulder stabilization. All new riprap would be supported by a woven geotextile
fabric that would also function to contain any backfill.
NCDOT states that they are submitting an application for a Special Use Permit from the
MacKay Island National Wildlife Refuge for the proposed project.
Anticipated Impacts
As proposed, the shoreline/road shoulder stabilization along NC 615 would result in the filling
of 39,681 sq. ft. of open water/shallow bottom and approximately 380 sq. ft. of fill in Coastal
Wetlands. The project would add approximately 9,405' of new shoreline stabilization and
repair/maintain 1,766' existing shoreline stabilization. The project is not expected to impact
navigability in the roadside canal or public trust access from the shoulder of the roadway, once the
project is completed. As a result of this project, approximately 704' of Coastal Wetlands would be
located between the by riprap marsh toe revetments and NC 615.
The project will temporarily impact Public Trust usage along the roadway during construction
activities, although access to the wildlife viewing area should not be impacted throughout the
project.
The proposed project would increase the safety of the traffic on NC 615 by stabilizing the
shoulder of the roadway and continue to provide a reliable roadway connection between the
community of Knotts Island, Currituck County.
Submitted by: Greg Daisey —Elizabeth City District — December 3, 2019
4