SW4240602_Stormwater Narrative_20241121

STORMWATER
NARRATIVE
For.
Fiddlers Ridge Subdivision
Bingham and Parks Road
Davie County, North Carolina
ADI Project No. 23-009
AL r
19701
�
Developer.
Baltimore RE,LLC
323 Riverbend Drive
Advance,North Carolina 27006
Prepared by:
Allied Design,Inc.
4720 Kester Mill Road
Winston-Salem,NC 27103
[phone]
[e-mail]

STORMWATER NARRATIVE
FIDDLERS RIDGE
TABLE OF CONTENTS
A. Introduction
B. Methodology
C. Site Design and Assessment
D. Conclusion
Appendix
A. Outlet Stabilization Calculations
B. Ditch Calculations
Allied Design Inc. Project No.: 23-009 Page 1

STORMWATER NARRATIVE
FIDDLERS RIDGE
A. Introduction
Fiddlers Ridge is a proposed 9.92-acre, 20 lot, single-family, residential
development located off Bingham and Parks Road in Davie County. Based on
anticipated development on the lots, the calculated BUA Percentage for the property
will be less than 24%. Consequently, the project can be permitted under the "Low
Density" (LD) provisions of the program. This will exempt the project from design and
construction of permanent, stormwater quality control measures.
Development under the LD option will require that the project meet the minimum
design criteria outlined in 15A NCAC 02H .1003. More specifically the project: 1)
must meet the Density Thresholds; 2) must utilize Dispersed Flow; 3) must provide
Vegetated Conveyances; 4) may be allowed to use Curb Outlet Systems; 5) must
provide Vegetated Setbacks; 6) requires that Stormwater Outlets be designed to not
cause erosion; and (7) requires that deed restrictions and protective covenants are
applied as necessary to protect the designed low density practices. Guidance for
development under The Low Density option is taken from the NCDEQ Stormwater
BMP Manual, Chapter E-1, "Low Density".
B. Low Density Design Considerations
1. Development Threshold
The total project area for the subdivision is 9.92 acres. The number of
proposed lots is 20. Deed restrictions will limit the maximum built upon area
per lot to 3,800 sf which will result in an overall BUA of less than 24%.
2. Dispersed Flow
As outlined in the Dispersed Flow requirements of the NCDEQ Stormwater
Manual this project must be designed to maximize dispersed flow through
vegetated areas and minimize channelization. Downspouts from the proposed
homes will spill onto grade and not be piped. This will allow infiltration and
Allied Design Inc. Project No.: 23-009 Page 2

STORMWATER NARRATIVE
FIDDLERS RIDGE
reduced erosion as runoff drains toward the roadway side ditches and swales
between homes.
3. Vegetative Conveyances
Stormwater runoff that cannot be maintained as shallow flow will be
transported by Vegetated Conveyances. These conveyances will be lined with
vegetation and designed to carry runoff from the 10-year storm at a non-
erosive velocity. Side slopes will be 3:1 maximum, the longitudinal slopes will
be held as flat as possible and a 2' minimum bottom width will be provided.
4. Curb Outlet Systems
The project does not include curb and gutter streets. The roadways will be
constructed with "ribbon" pavement and side ditches. Several inlets will be
placed along the side ditches to capture accumulated runoff. Outlets from the
pipe will discharge into vegetated swales designed in accordance with the
above guidelines. It should be noted that the storm drainage system as
illustrated on the plans has been previously installed.
5. Vegetated Setbacks
There are no streams located on the property. Vegetated setbacks will not be
required.
6. Stormwater Outlets
Stormwater outlets shall be designed such that discharge from the 10-year
storm will be released at non-erosive velocities. Outlet stabilization will be
provided at the stormwater outlets and will be designed in accordance with the
erosion control design manual and will.
7. Deed Restrictions and Protective Covenants
Allied Design Inc. Project No.: 23-009 Page 3

STORMWATER NARRATIVE
FIDDLERS RIDGE
The permittee will record deed restrictions and protective covenants in the
Davidson County Register of Deeds. These documents will limit the allowable
built upon area for each lot to 3,800 sf. The restriction and covenants will
"ensure the project is maintained in perpetuity consistent with the plans and
specifications approved by the permitting authority".
C. Conclusion
As noted, construction of this project has been completed. This post-construction
stormwater permit is being submitted for approval retroactively. This Stormwater
Narrative concludes that the original design of the project was completed in
accordance with the Low-Density provisions of the MDC. The design of the
stormwater drainage system intentionally releases stormwater water at the same
two pre-developed locations. The proposed grading plan and stormdrainage
system was designed to maintain pre-developed patterns as closely as possible.
This plan intends to provide dispersed flow and avoid concentrated discharge.
This report and the site construction documents demonstrate that:
1. The project meets the density threshold requirement of less than 24%
impervious (BUA) coverage.
2. The project utilizes dispersed flow to allow shallow release of stormwater
runoff, minimizes channelization and releases channelized flow through a
vegetated area.
3. Where vegetated conveyances are utilized, they are designed to be non-
erosive for the 25-year storm (exceeds the 10-year storm requirement), are
constructed with 3:1 (or flatter) side slopes, have a 2' minimum bottom
width.
4. Where curb outlets [inlets] are utilized, runoff is released such that a
vegetated areas are utilized, and outlet stabilization is used at the end of
the pipes.
Allied Design Inc. Project No.: 23-009 Page 4

STORMWATER NARRATIVE
FIDDLERS RIDGE
5. Vegetated setbacks are not required.
6. Stormwater outlets will include appropriately sized outlet stabilization.
7. Deed restrictions and protective covenants will be recorded in the
Davidson County register of deeds limiting the built upon area on each
individual lot to 3,800 sq. ft. of impervious coverage.
Allied Design Inc. Project No.: 23-009 Page 5

STORMWATER NARRATIVE
FIDDLERS RIDGE
Appendix
Allied Design Inc. Project No.: 23-009 Page 6

Allied Design Inc. PROJECT NAME Fiddler's Ridge
, Outlet Stabilization
CIVIL ENGINEERING❖ LAND SURVEYING PROJECT NO. 23 009 SHEET 1 OF 1
4720 Kester Mill Road BY WAB DATE 18-Mar-24
Winston-Salem,North Carolina 27103 CHECKED BY SMC REV 18-Mar-24
Ph.336.765.2377-Fax [phone]
Outlet Stabilization
3 0
Outlet 9 W = Do + La
Pipe y
diameter(Do)
La 80 _ y
ilwater <0.50o
��e1`ttil: y
tar i -
rgtro�Pp
H
�e' - r S
4
4
0
3 HIM IA -2
z J'
2 5 - 3
2
_ b
10 TJa
Iff 0 y y 2 C/Y
a n;
cul
D. Q
1V 25 y y
14 y 4
O
1+ v-15
rrl 11
v_10 d
i
v=5
3 5 10 20 50 100 200 500 1000
Discharge(0/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full,minimum tailwater condition(Tw<0.5 diameter).
Pipe apron NCDOT
Outlet Diameter Discharge d50 La W dmax thickness riprap
(in) (Cfs) (ft) (ft) (ft) (ft) (ft) Class
100 18 9.38 0.35 10.0 11.5 0.5 0.8 B
200 18 2.03 0.35 10.0 11.5 0.5 0.8 B
TAKEN FROM THE NORTH CAROLINA EROSION AND SEDIMENT CONTROL

DITCH SCHEDULE -25 YEAR STORM DESIGN
FIDDLER'S RIDGE
BERMUDA RUN, NORTH CAROLINA
March 26, 2024
Z Z
z w O = g �
O w w Cn� Q O z Q w a w u- w
U w Z w O a w } Q Q
O o' U ,L Z � � o O w
= z w O w z = = O cn = U O J
H � w U w O z a
~ J O 20 z O w w z
0 o zU � U o o m [n o > [n
(AC) (IN/HR) (CFS) (FT/FT) (FT) ("X" : 1) (FT) (FPS)
1 0.27 0.60 5 7.55 1.22 2.55% 2 3 0.26 1.65 S75 D
2 0.49 0.60 5 7.55 2.22 2.55% 2 3 0.35 2.10 S75 D
3 1.22 0.60 5 7.55 5.53 2.00% 2 3 0.57 2.60 S75 D
4 0.65 0.60 5 7.55 2.94 2.00% 2 3 0.43 2.05 S75 D
5 0.54 0.60 5 7.55 2.45 1.00% 2 3 0.53 1.30 S75 D
6 0.53 0.60 5 7.55 2.40 1.00% 2 3 0.52 1.29 S75 D
7 0.44 0.60 5 7.55 1.99 4.55% 2 3 0.26 2.74 S75 D
8 0.40 0.60 5 7.55 1.81 4.55% 2 3 0.25 2.63 S75 D
9 1.55 0.60 5 7.55 7.02 1.15% 12 3 0.38 1.42 S75 D
10 0.90 0.60 5 7.55 4.08 1.15% 12 3 0.29 1.10 S75 D
11 0.24 0.60 5 7.55 9.38 2.50% 4 3 0.51 3.30 S75 D
12 0.23 0.60 5 7.55 2.03 2.50% 8 3 0.18 1.33 S75 D

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#1
Name Ditch#1
Discharge 1.22
Channel Slope 0.0255
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 1.22 cfs 1.65 ft/s 0.26 ft 0.049 3.81 Ibs/ft2 0.32 Ibs/ft2 11.9 STABLE
Substrate
Unreinforced Straight 1.22 cfs 1.65 ft/s 0.26 ft 0.049 4 Ibs/ft2 0.42 Ibs/ft2 9.5 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#2
Name Ditch#2
Discharge 2.22
Channel Slope 0.0255
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 2.22 cfs 2.1 ft/s 0.35 ft 0.045 3.18 Ibs/ft2 0.4 Ibs/ft2 7.94 STABLE
Substrate
Unreinforced Straight 2.22 cfs 2.1 ft/s 0.35 ft 0.045 4 Ibs/ft2 0.55 Ibs/ft2 7.23 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#3
Name Ditch#3
Discharge 5.53
Channel Slope 0.02
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 5.53 cfs 2.6 ft/s 0.57 ft 0.042 2.79 Ibs/ft2 0.47 Ibs/ft2 5.91 STABLE
Substrate
Unreinforced Straight 5.53 cfs 2.6 ft/s 0.57 ft 0.042 4 Ibs/ft2 0.71 Ibs/ft2 5.6 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#4
Name Ditch#4
Discharge 2.94
Channel Slope 0.02
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 2.94 cfs 2.05 ft/s 0.43 ft 0.046 3.34 Ibs/ft2 0.38 Ibs/ft2 8.85 STABLE
Substrate
Unreinforced Straight 2.94 cfs 2.05 ft/s 0.43 ft 0.046 4 Ibs/ft2 0.54 Ibs/ft2 7.37 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#5
Name Ditch#5
Discharge 2.45
Channel Slope 0.01
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 2.45 cfs 1.3 ft/s 0.53 ft 0.057 4 Ibs/ft2 0.22 Ibs/ft2 18.11 STABLE
Substrate
Unreinforced Straight 2.45 cfs 1.3 ft/s 0.53 ft O.D57 4 Ibs/ft2 0.33 Ibs/ft2 12.16 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#6
Name Ditch#6
Discharge 2.4
Channel Slope 0.01
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 2.4 cfs 1.29 ft/s 0.52 ft 0.057 4 Ibs/ft2 0.22 Ibs/ft2 18.28 STABLE
Substrate
Unreinforced Straight 2.4 cfs 1.29 ft/s 0.52 ft O.D57 4 Ibs/ft2 0.33 Ibs/ft2 12.3 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#7
Name Ditch#7
Discharge 1.99
Channel Slope 0.0455
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Underlying Straight 1.99 cfs 2.74 ft/s 0.26 ft 0.039 2.42 Ibs/ft2 0.56 Ibs/ft2 4.29 STABLE
Substrate
Unreinforced Straight 1.99 cfs 2.74 ft/s 0.26 ft 0.039 4 Ibs/ft2 0.74 Ibs/ft2 5.4 STABLE
Vegetation

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#8
Name Ditch#8
Discharge 1.81
Channel Slope 0.0455
Channel Bottom Width 2
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 1.81 cfs 2.63 ft/s 0.25 ft 0.04 4 Ibs/ft2 0.71 Ibs/ft2 5.66 STABLE
Vegetation
Underlying Straight 1.81 cfs 2.63 ft/s 0.25 ft 0.04 2.49 Ibs/ft2 0.54 Ibs/ft2 4.59 STABLE
Substrate

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#9
Name Ditch#9
Discharge 7.02
Channel Slope 0.0115
Channel Bottom Width 12
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 7.02 cfs 1.42 ft/s 0.38 ft 0.055 4 Ibs/ft2 0.27 Ibs/ft2 14.84 STABLE
Vegetation
Underlying Straight 7.02 cfs 1.42 ft/s 0.38 ft 0.055 4 Ibs/ft2 0.25 Ibs/ft2 16.26 STABLE
Substrate

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#10
Name Ditch#10
Discharge 4.08
Channel Slope 0.0115
Channel Bottom Width 12
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 4.08 cfs 1.1 ft/s 0.29 ft 0.06 4 Ibs/ft2 0.21 Ibs/ft2 19.29 STABLE
Vegetation
Underlying Straight 4.08 cfs 1.1 ft/s 0.29 ft 0.06 4 Ibs/ft2 0.19 Ibs/ft2 20.73 STABLE
Substrate

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#11
Name Ditch#11
Discharge 9.38
Channel Slope 0.025
Channel Bottom Width 4
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 9.38 cfs 3.3 ft/s 0.51 ft 0.038 4 Ibs/ft2 0.8 Ibs/ft2 5 STABLE
Vegetation
Underlying Straight 9.38 cfs 3.3 ft/s 0.51 ft 0.038 2.27 Ibs/ft2 0.61 Ibs/ft2 3.71 STABLE
Substrate

NORTH H North American Green
M��IER���N 5401 St. Wendel-Cynthia na Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNELANALYSIS
>>>Ditch#12
Name Ditch#12
Discharge 2.03
Channel Slope 0.025
Channel Bottom Width 8
Left Side Slope 3
Right Side Slope 3
Low Flow Liner
Retardence Class D 2-6 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Fair 50-64%
Soil Type Clay Loam(CL)
Unreinforced Vegetation
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 2.03 cfs 1.33 ft/s 0.18 ft 0.054 4 Ibs/ft2 0.28 Ibs/ft2 14.35 STABLE
Vegetation
Underlying Straight 2.03 cfs 1.33 ft/s 0.18 ft 0.054 4 Ibs/ft2 0.26 Ibs/ft2 15.35 STABLE
Substrate