SW6231109_Stormwater Narrative_20240315

1. Stormwater Narrative
1.1. Project Description
Duke Energy Progress, LLC (DEP) plans to install a gravel laydown yard on PIN 0422-39-7835
owned by Kathryn G. Barker in Hope Mills, Cumberland County, North Carolina. The executed lease
agreement is included in Appendix B.
The proposed laydown yard will consist of a gravel pad, matted diversion ditch with berm, a chain-link
fence, and a wooden privacy fence along the residential abutting areas. The existing apron off
Braxton Road will be utilized to access the site. The total disturbed area is 9.1 acres.
Duke Energy is reconductoring a new transmission line in the vicinity of this project that will be
permitted separately. Duke Energy will use this laydown yard to support the transmission line project.
The laydown yard will be used to store equipment (bucket trucks, line trucks, cranes, pick-up trucks,
etc.) and materials (transmission poles, caissons, wire, hardware, etc.). Once the lease agreement is
over, the disturbed areas will be seeded, the erosion and sediment control and NCG01 permits will be
closed out, and the gravel yard will be returned to the existing conditions as farmland.
Gravel will be installed on top of existing ground once compacted. A laydown yard edge swale
consisting of a minor diversion ditch with berm on the outside is proposed to capture and control
stormwater that flows off the proposed site during rainfall events. The water will be directed to the
south side of the site where a 418-foot-long level spreader with filter strip will be constructed to
disperse flow offsite.
All erosion control measures shown on the plans are to be installed. The DEP representative (onsite
inspector) will determine if any additional erosion control measures are needed to ensure that all
sediment is kept onsite.
1.2. Existing Site Conditions
The overall property is 123.05 acres and the project area consists of 9 acres in the southwest corner
of the overall property. The project area drains to Grays Creek (see USGS map in Appendix C) which
is located in the Cape Fear River Basin. Grays Creek is classified as a Class B stream.
The existing project area is cleared land that is used for agriculture. The project area is relatively flat
and has an existing catch basin located along the southern property line with an 18" RCP that
connects to the street catch basin between the properties PIN 0422-67-0430 and PIN 0422-67-0495.
There is no existing impervious area within the project area.
1.3. Soils Characteristics
The attached USDA NRCS Soils Map (Appendix C) shows the soil characteristics within the project
area. See Appendix H for the full stormwater soil evaluation report.
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1.4. Proposed Erosion and Sedimentation Control Devices
Temporary measures will be used to limit erosion and contain sediment from disturbed areas prior to
the establishment of vegetation. Once construction is complete and vegetative cover has been
established, these measures will be removed. Temporary and permanent vegetative cover for
disturbed areas will consist of grasses as recommended by the North Carolina Erosion and
Sedimentation Control Planning and Design Manual (ESCPDM).
The temporary erosion and sediment control measures proposed for this site include wattles, a
construction entrance, silt fence, silt fence outlets, and temporary seeding measures, as required.
The above devices will filter sediment from runoff to prevent sediment from being deposited offsite,
while the temporary seeding will limit erosion during construction activities. All temporary construction
measures will be left in place, monitored, repaired, as needed, by the Contractor, and remain fully
functional while construction is underway. Permanent seeding is the proposed permanent erosion
control measure. Permanent stormwater swales along the edges of the laydown yard will be lined
with a jute liner and stabilized with permanent seeding.A level spreader-filter strip SCM will be
installed last and will be stabilized with No. 57 stone within the blind swale, slopes, and transition
area, and with sod along the filter strip.
All devices were designed based on guidelines and procedures as set forth in the North Carolina
Erosion and Sediment Control Planning and Design Manual.
The following measures and devices will be use on this phase of the project.
a. Temporary Wattles
Wattles will be used as necessary to prevent sediment from entering the work area, leaving
the construction site, and for directing flow to silt fence outlets.
b. Temporary Construction Entrance/Exit
A gravel construction entrance/exit will be installed to keep mud and sediment off of public
roads. See drawings for location and detail.
c. Temporary Silt Fence
Silt fence will be constructed as necessary to prevent sediment from entering the work area
or leaving the construction site. See drawings for locations and detail.
d. Temporary Silt Fence Gravel Outlet
Silt fence gravel outlets will be used as necessary to capture sediment from runoff along
boundary of silt fence.
e. Temporary Seeding
Seeding will be done to stabilize disturbed area with vegetation prior to the establishment of
permanent vegetation. See seeding schedule on plans. Wetlands will be allowed to naturally
re-vegetate.
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f. Permanent Seeding
Seeding will be done to stabilize disturbed upland areas with vegetation. See seeding
schedule on plans.
g. Rolled Erosion Control Product (RECP)
RECP consisting of jute mesh will be used on all drainage swales prior to establishment of
permanent vegetation. See detail on plans.
1.5. Maintenance and Sediment Disposal
All sediment and erosion control measures shall be inspected at regular intervals and following any
significant rainfall event of 1" of greater, but in no case less than once every week. Repairs to, or
replacement of, measures shall occur if necessary and accumulated sediment removed as needed.
Sediment shall be removed from all erosion control measures when the sediment storage volume of
the measure has become 50% full.
All removed sediment shall be disposed of in an approved manner at a location to be designated by
the Owner. Steps shall be taken at the disposal site to insure that further sediment transport does not
occur.
All disturbed areas shall be permanently seeded as soon as possible, but in no case later than 14
calendar days after construction activities are complete. Slopes shall be seeded within 7 calendar
days. Areas shall be seeded, fertilized and mulched in accordance with the Seeding Schedule.
Dewberry Duke Energy Progress, LLC I Barker Laydown Yard 13

1.6. Stormwater Management
Drainage on the project site generally flows south from the ridgeline that exists in the project area.
The water on this property is directed towards the catch basin with an 18" RCP drainage pipe in
between the properties PIN 0422-67-0430 and PIN 0422-67-0495, which then disperses to a 36" RCP
pipe under Walking Trail Way Road. There is no existing impervious within the project area. The
project is in a Phase II stormwater area that is subject to Phase II Post-Construction stormwater
regulations.
Most of the stormwater runoff will be managed with the incorporation of a level spreader—filter strip
(LS-FS) along the southern edge of the gravel which will evenly disperse water towards the existing
catch basin described above. Stormwater runoff that does not flow directly to the LS-FS is captured
by permanent swales located along the edges of the gravel yard. These swales will direct flow to the
LS-FS blind swale.
For the area to the north (labeled as DA-3 on the grading plan), the water will be treated via
disconnected impervious, and the water will be allowed to flow across the existing horse pasture.
Stormwater drainage patterns will remain unchanged from the existing site since all runoff is currently
getting into the existing storm system either onsite or once it gets to the roadway through neighboring
parcels. Stormwater will be treated consistent with low-density permitting standards.
1.7. Additional Permits
1. Cumberland County Special Use Permit (SUP)
2. Cumberland County Site Plan Permit
3. NCDEQ Erosion Control Permit
4. NCDOT Driveway Permit
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