SW4230601_Stormwater Narrative_20231019

Stormwater Treatment and
Management Narrative
Brentwood Park — Phase 9
Forsyth County, NC
JEG Job No. 20090
Revised October, 2023
Brentwood Park Phase 9 is a single-family detached subdivision located near Rural Hall in
Forsyth County. The proposed 36 lot subdivision is owned by Brentwood RH, LLC, and is
located on 23.9 acres within Brentwood Park. Entrances to the site will be provided off of
Brentwood Park Lane, Brentwood Park Place, and Spruce Pine Court. The site is located
in the Roanoke River Basin. Trick-urn Creek and several unnamed tributaries are located
on the site. The NCDEQ-DWR has classified Trick-urn Creek as Class C waters. The site
is located within a NPDES Phase II area. With a density of 1.5 dwelling units per acre, and
a built-upon area of 20.2%, Brentwood Park Phase 9 is a low-density development.
The roadway system consists of 22-ft wide ribbon paved roads with vegetated side ditches
designed to North Carolina Department of Transportation standard for future acceptance
into their system. The proposed water system is designed to Winston Salem/Forsyth
County system public standards and consists of 6-inch D.I. water lines with hydrants,
valves, and water services. Sewer service will be provided by individual private septic and
ground absorption systems on each lot.
Site grading on the 23.9-acre site has been limited to 6.4 acres within the roadway limits
and areas required for three temporary sediment basins. There are indications that grading
at the site was initiated at some time in the past as evidenced by partial road grading and
remnants of sediment basins. A stream and wetland determination was conducted by Pilot
Environmental, Inc. at the site. A copy of the report is attached for reference, which
includes soil information/maps, and a USGS location map. Construction of new homes and
roads will take place on higher ground, resulting in no impacts to stream or wetlands
identified in the report. 30-ft undisturbed buffers have been proposed along all perennial
and intermittent streams identified in the report.
Vegetated roadside ditches are utilized along all roadways with variable bottom widths and
side slopes of 3:1. Swale calculations are included that show no erosion should occur
during the 10-year storm event, and that velocities are within established limits for post
construction grassed swales.
Riprap stormwater outlets have been engineered to prevent downslope erosion at all
discharge points while also creating dispersed flow.
Stormwater within the development,is transported by vegetated conveyances designed in
accordance with NCDEQ Standards. Piping has been limited to required culverts under
roadways or within areas where erosion protection is an issue. In addition, the two primary
stormwater discharge points have been provided with curb outlet systems to increase the
quality of runoff from the development. The development's low density and built upon area,
in conjunction with vegetated conveyance systems, minimized piping, and curb outlet
systems at primary discharge points meet the design objective for low density projects.