SW6240202_Stormwater Narrative_20240219

B N K BONS SS NIXONU I KENNEDYCLTING ENGINEERS 6310 Chapel Hill Road
, Ste 2760750Ra
919.861.4422 I bnkinc.com
Cotton Farm Phase 2 and 3 Subdivision
Stormwater Narrative
Cotton Farm Phase 2 and 3 Subdivision consists of approximately 105.84 acres with a proposed
unit account of 73 large residential home sites. The project falls under Harnett County zoning and
received preliminary approval on April 7, 2021. With this approval the site is entitled to proceed
with engineering drawings. The Phases 2 and 3 together will consist of 3.20 acres of roads, and
9.38 acres of building and driveways. Maximum impervious area per lot is restricted to 5,600
square feet. Total road and Lot impervious equate out to 11.89 percent which is under the
threshold of 12 percent and qualifies as "Low Density Development". Stormwater runoff
conveyances are limited to roadside ditches and only 4 intersection cross pipes. No stormwater
treatment devices are being proposed other than the release of runoff disbursed into natural open
space areas. The 5 storm pipes have velocity dissipaters at the discharge ends. Wetlands do
exist within Phase 2 and 3 but are not impacted by the development of the roads or residential
lots. Predominate soils are Cecil fine sandy loam and Pactolus loamy sand. These soils rate as
moderate perk ability and well drained. Phases 2 and 3 dedicates approximately 29.90 acres to
open space.
Erosion Control Narrative
Cotton Farm Phase 2 and 3 consists of 15.3 acres of disturbed area. Disturbed area is limited to
road and temporary sediment control devices. Devices used are Sediment Traps for the smaller
drainage areas and skimmer basins for drainage areas just under 5 acres and for all drainage
areas over 5 acres. The plan also specifies a small amount of silt fence (SF) and super silt fence
(SSF) in areas that either have a very small drainage area (SF) or in tight sensitive areas (SSF).
Site soils basically consist of Cecil and Pacolet Series sandy loam. Storm piping is limited to just
a few intersections. Roadside ditches are the primary device for collecting stormwater. Since this
project qualifies as Low Density no permanent stormwater devices (SCM's) are proposed.
The Following Government Agency reviews will be required:
• NCDOT— Roads
• Harnett County Reginal Water— Domestic water and fire
• NCDENR Stormwater Management— Stormwater runoff
> NCDENR Land Quality Section — Erosion Control/NCG01/COC
1