SW3190804_2712-Summary Paragraphs_8/20/2019

Pine Forest II
Storm Drain/Erosion Control Project Report
A. PROJECT DESCRIPTION
Project Summary
The Pine Forest II Subdivision project is a Planned Development located west of Interstate 77 off of
Amity Hill Road in Iredell County, North Carolina. This development consists of approximately 29.36 Ac.
This project will consist of 70 single family residential lots.
This property has a Tax Parcel Number of 4742-58-9712, Deed Book Number of 2470 and Deed Book
Page Number of 1971.
The predominant soil types within the proposed limits of construction are Cecil sandy clay loam and
Hiwassee fine sandy loam; all of which belong to the Soil Hydraulic Group B (as taken from the Web Soil
Survey 2.1— National Cooperative Soil Survey by NRCS).
The disturbance for the site will encompass roughly 23.88 acres. The site will encounter two phases of
erosion and sediment control management, beginning with an initial phase. Initial clearing, grading and
infrastructure placement will occur during this phase. The last phase (stabilization or final phase) will
include paving and stabilization of the site. Given the amount of grading work that will take place, the
majority of the erosion control is best managed through the use of sediment basins; with temporary
diversion ditches to help channel flow to the aforementioned basins. Accessory features such as inlet
protection, silt fence, and concentration outlets will also be used to assist with the bypass areas and
smaller areas of concentrated flow.
Two proposed sediment basins (Basin #100 and Basin #200) have been specified for the initial phase
erosion control. Sediment Basin #100 and Sediment Basin #200 will remain active during the final phase
of erosion control and sediment management. All storm drainage systems will be installed per plans
with no stubbed pipes or temporary pipes.
B. STORMWATER MANAGEMENT
Pre and Post development flows were analyzed to determine if storm water detention would be
necessary for the higher level storm events. The pre -development analysis point was conducted along
the existing creek which runs west/east on the south side of the area. The Post development analysis
was analyzed at the same location which includes BMP #100 and BMP #200.
Pre and Post Development runoff summaries can be found in Section V of this project report and in
summary for the 2-year, 10-year, 50-year and 100-year Storm Events.
C. WATER QUALITY
There are 2 main drainage areas that make up the combined flow for Pine Forest II. The 2 main drainage
areas make up the developed areas of the site. The larger of the 2 collects approximately 55% of the
total runoff of the site. This runoff will drain to BMP #100.
The 2nd drainage area is primarily flow from the remaining 45% of the development. This runoff will
drain to BMP #200.

Pine Forest II
Storm Drain/Erosion Control Project Report Project Summary
Both of these drainage areas have been designed to collect the bulk of the sites impervious runoff and
treat it before releasing downstream. The BMP water quality design can be found in Section VI of the
report booklet.
D. STORM DRAINAGE SYSTEM
An analysis of both receiving storm drainage systems within the Pine Forest II site was conducted to
verify the drainage systems would not surcharge or be beyond capacity due to the drainage areas and
the storm water runoff from the site for the 10-year, 24-hour rainfall intensity, and all yard inlets have
been evaluated for sump capacity using the 10-year, 24-hour rainfall intensity.
For the analysis of the infrastructure, RJH utilized a combination of Aerial topography for the area and
proposed lot/road grading to evaluate each of the storm drain systems. Storm systems #100 and #200
are new systems within the limits of the Pine Forest II project site. These storm systems function with
the design parameters set forth by the City of Statesville, Iredell County and NCDOT for both pipe design
and inlet spared capacity.
All systems have been fitted with a properly sized riprap apron at the outflow for energy dissipation. All
proposed storm drain profiles have been designed to limit the hydraulic gradient line (HGL) to no closer
than 0.5' below the weir/rim elevation.
End Report