Olsen Park Phase 2 SWM Narrative_v1Olsen Park
5510 Olsen Park Lane
Wilmington, NC
Stormwater Management
Design Narrative & Calculations
Construction Drawing Submittal #1
July 2023
Prepared by:
CLH Design, PA
Cert: C-1595
TABLE OF CONTENTS
I. Design Narrative
II. Supporting Calculations
a. Pre/Post-Development Runoff Calculations (Hydrographs Report)
b. Culvert Sizing Calculations
c. Permanent Outlet Protection Calculations
d. Channel Sizing Calculations
III. Maps
a. FIRM Map
b. Soils Map
c. USGS Map
IV. Deed
Stormwater Management Design Narrative
Olsen Park
CLH Project No.: 21-140
July 2023
PROJECT DESCRIPTION
Olsen Park is a low-density community park located on a 89.4-acre site off Olsen Park Lane in New
Hanover County, North Carolina. The site currently drains to existing ditches and streams surrounding the
property which ultimately discharging into Smith Creek. Smith Creek is classified as C;Sw waters and the
stream index number is 18-74-63. Soils on the site consist primarily of Seagate (Se, Hydrologic Group B)
soils. Phase 2 of this project will consist of 19.7-acres of disturbed area including the construction of an
asphalt trail around the perimeter of the site, asphalt paving of existing gravel driveway, two multi-
purpose fields, four pickleball courts, and associated grading/swales. Proposed improvements will add
90,843 ft2 of impervious surface resulting in a total of 398,653 ft2 (10.2%) total impervious surface area.
METHODOLOGY
Hydraflow Hydrographs (Autodesk Civil 3D 2021) was used to calculate curve numbers, times of
concentration, and determine the pre-development and post-development peak flows in the project area
for the 2-year, 10-year and 25-year storms. Rainfall intensity values were obtained from NOAA Atlas 14.
Peak flow comparison then utilized the allowable peak flow values provided in calculations for two
previously approved projects on this site, Olsen Park Phase 1 and Miracle Field. A drainage system
consisting of swales and culverts adjacent to the surrounding asphalt paths was included in proposed
improvements. Sizing calculations for this system were based on the 10-year storm and are included in
this report.
CONCLUSION
This project has been designed to meet the minimum requirements of the New Hanover County
Stormwater Design Manual and the State of North Carolina Department of Natural Resources. Overall
There is an overall net increase in the post-development peak flows for the 2-year, 10-year and 25-year
storm events as shown in the table below. However, over-detention was provided in the Phase 1 of this
project as shown in the previously approved calculations for that project. Additional detention is thus not
required as peak flow rates are still below the allowable maximum.
Pre/Post-Development Peak Flow Summary (cfs)
Storm Event
2-
Year
10-
Year
25-
Year
Pre-Development Runoff (Project Area) 22.52 48.46 68.45
Post-Development Runoff (Project Area) 25.65 52.55 72.85
Pre/Post Peak Flow Increase 3.13 4.09 4.40
Allowable Peak Flow Increase
(Miracle Field Project) 12.54 31.44 46.94
New Allowable Peak Flow Increase 9.41 27.35 42.54
Per the active stormwater permit SW8-090217 which allowed for a maximum built-upon area of 934,351
square feet (24% of site area). Thus, runoff treatment for water quality is also not required as the resulting
impervious surface is still below this threshold as shown in the table below. Please see the Impervious
Surface Map attached to this report.
Allowable Impervious Surface Summary
Existing Built-Upon Area 307,810
Proposed Built-Upon Area 90,843
New Built-Upon Area 398,653
Permitted Built-Upon Area 934,351
Future Available Built-Upon Area 535,698
Pre/Post-Development Runoff
Calculations (Hydrographs Report)
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 1
Pre-Development
Hydrograph type = SCS Runoff Peak discharge = 22.52 cfs
Storm frequency = 2 yrs Time to peak = 744 min
Time interval = 2 min Hyd. volume = 127,361 cuft
Drainage area = 18.600 ac Curve number = 71*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 4.66 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(18.600 x 71)] / 18.600
1
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
4.00 4.00
8.00 8.00
12.00 12.00
16.00 16.00
20.00 20.00
24.00 24.00
Q (cfs)
Time (min)
Pre-Development
Hyd. No. 1 -- 2 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 2
Post-Development
Hydrograph type = SCS Runoff Peak discharge = 25.65 cfs
Storm frequency = 2 yrs Time to peak = 744 min
Time interval = 2 min Hyd. volume = 143,299 cuft
Drainage area = 18.600 ac Curve number = 74*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 4.66 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(2.230 x 98) + (16.370 x 71)] / 18.600
2
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
4.00 4.00
8.00 8.00
12.00 12.00
16.00 16.00
20.00 20.00
24.00 24.00
28.00 28.00
Q (cfs)
Time (min)
Post-Development
Hyd. No. 2 -- 2 Year
Hyd No. 2
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 1
Pre-Development
Hydrograph type = SCS Runoff Peak discharge = 48.46 cfs
Storm frequency = 10 yrs Time to peak = 742 min
Time interval = 2 min Hyd. volume = 267,830 cuft
Drainage area = 18.600 ac Curve number = 71*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 7.23 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(18.600 x 71)] / 18.600
3
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (min)
Pre-Development
Hyd. No. 1 -- 10 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 2
Post-Development
Hydrograph type = SCS Runoff Peak discharge = 52.55 cfs
Storm frequency = 10 yrs Time to peak = 742 min
Time interval = 2 min Hyd. volume = 290,077 cuft
Drainage area = 18.600 ac Curve number = 74*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 7.23 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(2.230 x 98) + (16.370 x 71)] / 18.600
4
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
Q (cfs)
Time (min)
Post-Development
Hyd. No. 2 -- 10 Year
Hyd No. 2
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 1
Pre-Development
Hydrograph type = SCS Runoff Peak discharge = 68.45 cfs
Storm frequency = 25 yrs Time to peak = 742 min
Time interval = 2 min Hyd. volume = 378,022 cuft
Drainage area = 18.600 ac Curve number = 71*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 9.08 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(18.600 x 71)] / 18.600
5
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
70.00 70.00
Q (cfs)
Time (min)
Pre-Development
Hyd. No. 1 -- 25 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Thursday, 05 / 18 / 2023
Hyd. No. 2
Post-Development
Hydrograph type = SCS Runoff Peak discharge = 72.85 cfs
Storm frequency = 25 yrs Time to peak = 742 min
Time interval = 2 min Hyd. volume = 403,469 cuft
Drainage area = 18.600 ac Curve number = 74*
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 31.20 min
Total precip. = 9.08 in Distribution = Type III
Storm duration = 24 hrs Shape factor = 484
* Composite (Area/CN) = [(2.230 x 98) + (16.370 x 71)] / 18.600
6
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
70.00 70.00
80.00 80.00
Q (cfs)
Time (min)
Post-Development
Hyd. No. 2 -- 25 Year
Hyd No. 2
Culvert Sizing Calculations
STORM DRAINAGE / HYDRAULIC GRADE LINE DATE DESIGN PHASE
ANALYSIS 5/2/2023 PRELIM /x /
PROJECT NAME PROJECT NO CONSTR / /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Storm Event= 10
n= 0.013 STORM DRAINAGE SCHEDULE CONTINUED
m= -2.70
b= 14.02
I= 9.67 INLET Tc I Cc
INLET INLET Cc INLET TOTAL INLET PIPE TIME RUNOFF
AREA AREA IMPERVIOUS RUNOFF DISCHARGE AREAS TIME TIME OF CONC. INTENSITY COEFF.
(SF) (AC) (%) COEFF. (CFS) (AC) (MIN) (MIN) (MIN) (IN/HR)
29,769 0.68 10 0.28 1.71 0.68 5.00 0.00 5.00 9.67 0.28
34,927 0.80 15 0.31 2.28 0.80 5.00 0.00 5.00 9.67 0.31
338,858 7.78 15 0.31 22.11 7.78 5.00 0.00 6.20 9.09 0.31
49,695 1.14 0 0.20 2.07 1.14 5.00 0.00 5.00 9.67 0.20
49,695 1.14 0 0.20 2.07 1.14 5.00 0.00 5.00 9.67 0.20
15,234 0.35 0 0.20 0.64 0.35 5.00 0.00 5.00 9.67 0.20
47,133 1.08 30 0.43 4.18 1.08 5.00 0.00 5.00 9.67 0.43
39,370 0.90 0 0.20 1.64 0.90 5.00 0.00 5.00 9.67 0.20
17,774 0.41 20 0.35 1.30 0.41 5.00 0.00 5.00 9.67 0.35
50,333 1.16 0 0.20 2.10 1.16 5.00 0.00 5.00 9.67 0.20
115,855 2.66 5 0.24 5.74 2.66 5.00 0.00 5.00 9.67 0.24
228,070 5.24 5 0.24 11.31 5.24 5.00 0.00 5.00 9.67 0.24
73,974 1.70 5 0.24 3.67 1.70 5.00 0.00 5.00 9.67 0.24
B1 TO B2
B9 to B10
B5 TO B6
B7 TO B8
CULVERT #
A5 TO A6
A7 TO A8 (PIPE 1)
A7 TO A8 (PIPE 2)
B3 TO B4
A3 TO A4
A1 TO A2
A11 TO A12
A9 TO A10
A13 TO A14
21-140 STRM.xlsSTORM Page 1 of 4
Storm Event= 10
n= 0.013
m= -2.70
b= 14.02
I= 9.67
B1 TO B2
B9 to B10
B5 TO B6
B7 TO B8
CULVERT #
A5 TO A6
A7 TO A8 (PIPE 1)
A7 TO A8 (PIPE 2)
B3 TO B4
A3 TO A4
A1 TO A2
A11 TO A12
A9 TO A10
A13 TO A14
STORM DRAINAGE / HYDRAULIC GRADE LINE DATE DESIGN PHASE
ANALYSIS 5/2/2023 PRELIM /x /
PROJECT NAME PROJECT NO CONSTR / /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
STORM DRAINAGE SCHEDULE - CONTINUED
Q Q PATH C/L
SIDE-CAPACITY SEGMENT UPPER LOWER TOP PIPE
DISCHARGE STREAM SLOPE DIA. (FULL) V FULL LENGTH TIME INV. INV. ELEV. COVER
(CFS) (CFS) (FT/FT) (IN) (CFS) (FPS) (FT) (MIN) (FT) (FT) (FT) (FT)
1.82 0.00 0.0067 12 2.9 3.7 30 0.14 33.70 33.50 36.20 1.51
2.42 0.00 0.0056 15 4.8 3.9 125 0.53 33.30 32.60 36.30 1.99
22.11 0.00 0.0057 24 17.1 5.4 35 0.11 29.20 29.00 32.50 1.22
2.21 0.00 0.0067 12 2.9 3.7 30 0.14 31.20 31.00 33.50 1.31
2.21 0.00 0.0067 12 2.9 3.7 30 0.14 31.20 31.00 33.50 1.31
0.68 0.00 0.0068 12 2.9 3.7 44 0.20 35.60 35.30 37.80 1.26
4.45 0.00 0.0042 15 4.2 3.4 120 0.59 35.00 34.50 37.30 1.19
1.75 0.00 0.0044 12 2.4 3.0 225 1.24 35.50 34.50 37.50 1.41
1.38 0.00 0.0057 12 2.7 3.4 35 0.17 34.80 34.60 37.60 1.81
2.24 0.00 0.0171 12 4.7 5.9 35 0.10 33.50 32.90 35.30 1.01
6.11 0.00 0.0467 15 14.0 11.4 30 0.04 28.20 26.80 30.15 1.29
12.03 0.00 0.0333 18 19.2 10.8 30 0.05 30.50 29.50 33.50 1.86
3.90 0.00 0.0100 12 3.6 4.5 30 0.11 30.80 30.50 33.30 1.56
21-140 STRM.xlsSTORM Page 2 of 4
Storm Event= 10
n= 0.013
m= -2.70
b= 14.02
I= 9.67
B1 TO B2
B9 to B10
B5 TO B6
B7 TO B8
CULVERT #
A5 TO A6
A7 TO A8 (PIPE 1)
A7 TO A8 (PIPE 2)
B3 TO B4
A3 TO A4
A1 TO A2
A11 TO A12
A9 TO A10
A13 TO A14
STORM DRAINAGE / HYDRAULIC GRADE LINE DATE DESIGN PHASE
ANALYSIS 5/2/2023 PRELIM /x /
PROJECT NAME PROJECT NO CONSTR / /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
0
HYDRAULIC GRADE LINE CONTINUED
BEND LOSS K's
90° = 0.70 70° = 0.61 50° = 0.47 30° = 0.28 20° = 0.16
80° = 0.66 60° = 0.55 40° = 0.38 25° = 0.22 15° = 0.10
PIPE HYDRAULIC SIDESTREAM HEAD LOSS BEND FRICTION FRICTION
AREA RADIUS SUMMATION Hf Hc He Hb Ht LOSS SLOPE VELOCITY
(FT) (FT) (CFS)K (FT/FT) (FPS)
0.7854 0.2500 0.00 0.08 0.00 0.00 0.00 0.00 0.00 0.0026 INLET
1.2272 0.3125 0.00 0.18 0.00 0.00 0.00 0.00 0.00 0.0014 INLET
3.1416 0.5000 0.00 0.33 0.00 0.00 0.00 0.00 0.00 0.0095 INLET
0.7854 0.2500 0.00 0.11 0.03 0.00 0.00 0.15 0.00 0.0038 2.80
0.7854 0.2500 0.00 0.11 0.03 0.00 0.00 0.15 0.00 0.0038 2.80
0.7854 0.2500 0.00 0.02 0.00 0.00 0.00 0.02 0.00 0.0004 0.86
1.2272 0.3125 0.00 0.57 0.05 0.00 0.00 0.62 0.00 0.0047 3.61
0.7854 0.2500 0.00 0.54 0.02 0.00 0.00 0.56 0.00 0.0024 2.22
0.7854 0.2500 0.00 0.05 0.01 0.00 0.00 0.06 0.00 0.0015 1.75
0.7854 0.2500 0.00 0.14 0.03 0.00 0.00 0.17 0.00 0.0039 2.84
1.2272 0.3125 0.00 0.27 0.10 0.00 0.00 0.36 0.00 0.0089 4.96
1.7671 0.3750 0.00 0.39 0.18 0.00 0.00 0.57 0.00 0.0130 6.78
0.7854 0.2500 0.00 0.36 0.10 0.00 0.00 0.45 0.00 0.0120 4.95
21-140 STRM.xlsSTORM Page 3 of 4
Storm Event= 10
n= 0.013
m= -2.70
b= 14.02
I= 9.67
B1 TO B2
B9 to B10
B5 TO B6
B7 TO B8
CULVERT #
A5 TO A6
A7 TO A8 (PIPE 1)
A7 TO A8 (PIPE 2)
B3 TO B4
A3 TO A4
A1 TO A2
A11 TO A12
A9 TO A10
A13 TO A14
STORM DRAINAGE / HYDRAULIC GRADE LINE
ANALYSIS
PROJECT NAME
Olsen Park
LOCATION
Wilmington, NC
HYDRAULIC GRADE LINE - CONTINUED
INLET W.S. ELEV.
DOWNSTREAM OUTLET INLET UPSTREAM FLOW
HGL CONTOL CONTROL HGL CONDITION
(FT) (FT) (FT) (FT) CONTROL
34.30 34.30 34.43 34.43 INLET 0.80 0.73 OK OK 1.77
33.60 33.60 34.09 34.09 INLET 0.80 0.63 OK OK 2.21
30.60 30.60 32.34 32.34 INLET 0.80 1.57 USE O-RING OK 0.16
31.80 31.95 32.04 32.04 INLET 0.80 0.84 OK OK 1.46
31.80 31.95 32.04 32.04 INLET 0.80 0.84 OK OK 1.46
36.10 36.12 36.13 36.13 INLET 0.80 0.53 OK OK 1.67
35.50 36.12 36.19 36.19 INLET 0.80 0.95 OK OK 1.11
35.30 35.86 36.21 36.21 INLET 0.80 0.71 OK OK 1.29
35.40 35.46 35.43 35.46 OUTLET 0.80 0.66 OK OK 2.14
33.70 33.87 34.35 34.35 INLET 0.80 0.85 OK OK 0.95
27.80 28.16 29.89 29.89 INLET 0.80 1.36 USE O-RING OK 0.26
30.70 31.27 33.25 33.25 INLET 0.80 1.83 USE O-RING OK 0.25
31.30 31.75 32.36 32.36 INLET 0.80 1.56 USE O-RING OK 0.94
HGL
INSIDE
PIPE UP
(HW/D<1)
HGL
INSIDE
PIPE
DOWN
(HW/D<1)
INSIDE
STRUCTURE
?
INSIDE
PIPE?
FREEBOARD
(FT)
21-140 STRM.xlsSTORM Page 4 of 4
Permanent Outlet Protection
Calculations
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A2 Q10/Qfull =0.63
Pipe Dia= 12 in V/Vfull = 1.06
Q10 =1.82 cfs V = 3.9 fps
Qfull = 2.90 cfs
Vfull = 3.70 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 6 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 7 ft
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A4 Q10/Qfull =0.50
Pipe Dia= 15 in V/Vfull = 1.00
Q10 =2.42 cfs V = 3.9 fps
Qfull = 4.80 cfs
Vfull = 3.90 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 8 ft
Width (W1) = 3xDia = 4 ft
Width (W2) = Dia + L = 10 ft
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A6 Q10/Qfull =1.00
Pipe Dia= 24 in V/Vfull = 1.14
Q10 =17.10 cfs V = 6.2 fps
Qfull = 17.10 cfs
Vfull = 5.40 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 8 in
DMAX = 12 in
Riprap Class = B
Apron Thickness = 18 in
Apron Length (L) = 12 ft
Width (W1) = 3xDia = 6 ft
Width (W2) = Dia + L = 14 ft
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A8 Q10/Qfull =0.76
Pipe Dia= 12 in V/Vfull = 1.10
Q10 =2.21 cfs V = 4.1 fps
Qfull = 2.90 cfs
Vfull = 3.70 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 6 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 7 ft
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A6 Q10/Qfull =1.00
Pipe Dia= 24 in V/Vfull = 1.14
Q10 =17.10 cfs V = 6.2 fps
Qfull = 17.10 cfs
Vfull = 5.40 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 8 in
DMAX = 12 in
Riprap Class = B
Apron Thickness = 18 in
Apron Length (L) = 12 ft
Width (W1) = 3xDia = 6 ft
Width (W2) = Dia + L = 14 ft
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= A8 Q10/Qfull =0.76
Pipe Dia= 12 in V/Vfull = 1.10
Q10 =2.21 cfs V = 4.1 fps
Qfull = 2.90 cfs
Vfull = 3.70 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 6 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 7 ft
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= B2 Q10/Qfull =0.51
Pipe Dia= 12 in V/Vfull = 1.00
Q10 =1.38 cfs V = 3.4 fps
Qfull = 2.70 cfs
Vfull = 3.40 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 6 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 7 ft
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= B4 Q10/Qfull =0.48
Pipe Dia= 12 in V/Vfull = 0.99
Q10 =2.24 cfs V = 5.8 fps
Qfull = 4.70 cfs
Vfull = 5.90 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 8 in
DMAX = 12 in
Riprap Class = B
Apron Thickness = 18 in
Apron Length (L) = 8 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 9 ft
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection (to Flat Ground)
FES No.= B10 Q10/Qfull =1.00
Pipe Dia= 12 in V/Vfull = 1.14
Q10 =3.60 cfs V = 5.1 fps
Qfull = 3.60 cfs
Vfull = 4.50 fps
Outlet Conditions: Flat area, no defined channel
From Fig. 8.06.a:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 9 in
Apron Length (L) = 6 ft
Width (W1) = 3xDia = 3 ft
Width (W2) = Dia + L = 7 ft
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection
FES No.=Q10/Qfull =0.23
Pipe Dia= 12 in V/Vfull = 0.81
Q10 =0.68 cfs V = 3.0 fps
Qfull = 2.90 cfs
Vfull = 3.70 fps
From Fig. 8.06.b.1: Zone = 1
From Fig. 8.06.b.2:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 12 in
Apron Length = 4 ft
Apron Width = 3xDia = 3 ft
Riprap Apron Outlet Protection
FES No.= A12 Q10/Qfull =1.06
Pipe Dia= 15 in V/Vfull = 1.13
Q10 =4.45 cfs V = 3.9 fps
Qfull = 4.20 cfs
Vfull = 3.40 fps
From Fig. 8.06.b.1: Zone = 1
From Fig. 8.06.b.2:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 12 in
Apron Length = 5 ft
Apron Width = 3xDia = 4 ft
A10
OUTLET PROTECTION DATE DESIGN PHASE
DESIGN 5/2/2023 PRELIM / /
PROJECT NAME PROJECT NO CONSTR / X /
Olsen Park 21-140 REVISION / /
LOCATION BY RECORD / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
Riprap Apron Outlet Protection
FES No.= A14 Q10/Qfull =0.73
Pipe Dia= 12 in V/Vfull = 1.09
Q10 =1.75 cfs V = 3.3 fps
Qfull = 2.40 cfs
Vfull = 3.00 fps
From Fig. 8.06.b.1: Zone = 1
From Fig. 8.06.b.2:D50 = 4 in
DMAX = 6 in
Riprap Class = A
Apron Thickness = 12 in
Apron Length = 4 ft
Apron Width = 3xDia = 3 ft
Channel Sizing Calculations
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-1 Drainage Area: 0.98 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 430 ft Intensity: 9.67 in/hr
Section Slope: 1.40 % Runoff Coeff: 0.37
Ret Class:D Discharge:3.51 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 3.51 cfs flow by Rational Method
n = 0.075 Grass Manning's Coefficient (dimensionless)
S = 0.014 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =1.49 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.40 1.28 4.53 0.28 0.55 shallow
0.00 0.50 0.75 3.16 0.24 0.29 shallow
2.00 0.60 2.28 5.79 0.39 1.22 shallow
2.00 0.66 2.63 6.17 0.43 1.49 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.66 ft Depth O.K.
Velocity= 1.33 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.58 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-1 Drainage Area:0.98 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:430 ft Intensity:7.42 in/hr
Section Slope: 1.40 % Runoff Coeff: 0.37
Lining Type: Curled Wood Mat Discharge: 2.69 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =2.69 cfs flow by Rational Method
n = 0.066 Manning's Coefficient (dimensionless)
S = 0.014 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =1.007 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.80 3.52 7.06 0.50 2.213 deep
2 0.70 2.87 6.43 0.45 1.677 deep
2 0.60 2.28 5.79 0.39 1.224 deep
2 0.54 1.95 5.42 0.36 0.991 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.54 ft
Velocity= 1.38 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.47 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-2 Drainage Area: 3.33 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 550 ft Intensity: 9.67 in/hr
Section Slope: 1.20 % Runoff Coeff: 0.32
Ret Class:D Discharge:10.30 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 10.30 cfs flow by Rational Method
n = 0.055 Grass Manning's Coefficient (dimensionless)
S = 0.012 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =3.47 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.70 2.87 6.43 0.45 1.68 shallow
0.00 0.80 1.92 5.06 0.38 1.01 shallow
2.00 0.90 4.23 7.69 0.55 2.84 shallow
2.00 0.99 4.92 8.26 0.60 3.48 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.99 ft Depth O.K.
Velocity= 2.09 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.74 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-2 Drainage Area:3.33 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:550 ft Intensity:7.42 in/hr
Section Slope: 1.20 % Runoff Coeff: 0.32
Lining Type: Curled Wood Mat Discharge: 7.91 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =7.91 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0.012 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =1.695 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 shallow
2 0.60 2.28 5.79 0.39 1.224 shallow
2 0.65 2.57 6.11 0.42 1.440 shallow
2 0.70 2.87 6.43 0.45 1.677 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.70 ft
Velocity= 2.75 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.52 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-3 Drainage Area: 3.05 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 570 ft Intensity: 9.67 in/hr
Section Slope: 0.88 % Runoff Coeff: 0.20
Ret Class:D Discharge:5.90 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 5.90 cfs flow by Rational Method
n = 0.065 Grass Manning's Coefficient (dimensionless)
S = 0.0088 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =2.74 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.70 2.87 6.43 0.45 1.68 shallow
0.00 0.75 1.69 4.74 0.36 0.85 shallow
2.00 0.80 3.52 7.06 0.50 2.21 shallow
2.00 0.89 4.16 7.63 0.54 2.77 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.89 ft Depth O.K.
Velocity= 1.42 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.49 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-3 Drainage Area:3.05 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:570 ft Intensity:7.42 in/hr
Section Slope: 0.88 % Runoff Coeff: 0.20
Lining Type: Curled Wood Mat Discharge: 4.53 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =4.53 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0.0088 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =1.133 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 shallow
2 0.60 2.28 5.79 0.39 1.224 deep
2 0.65 2.57 6.11 0.42 1.440 deep
2 0.70 2.87 6.43 0.45 1.677 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.70 ft
Velocity= 1.58 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.38 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-4 Drainage Area: 0.41 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 221 ft Intensity: 9.67 in/hr
Section Slope: % Runoff Coeff: 0.20
Ret Class:D Discharge:0.79 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 0.79 cfs flow by Rational Method
n = 0.065 Grass Manning's Coefficient (dimensionless)
S = 0 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =#DIV/0!quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.70 2.87 6.43 0.45 1.68 #DIV/0!
0.00 0.75 1.69 4.74 0.36 0.85 #DIV/0!
2.00 0.80 3.52 7.06 0.50 2.21 #DIV/0!
2.00 0.89 4.16 7.63 0.54 2.77 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.89 ft Depth O.K.
Velocity= 0.19 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.00 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-4 Drainage Area:0.41 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:221 ft Intensity:7.42 in/hr
Section Slope: 0.00 % Runoff Coeff: 0.20
Lining Type: Curled Wood Mat Discharge: 0.61 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =0.61 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =#DIV/0!quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 #DIV/0!
2 0.60 2.28 5.79 0.39 1.224 #DIV/0!
2 0.65 2.57 6.11 0.42 1.440 #DIV/0!
2 0.70 2.87 6.43 0.45 1.677 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.70 ft
Velocity= 0.21 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.00 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-5 Drainage Area: 1.88 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 718 ft Intensity: 9.67 in/hr
Section Slope: 0.97 % Runoff Coeff: 0.20
Ret Class:D Discharge:3.64 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 3.64 cfs flow by Rational Method
n = 0.075 Grass Manning's Coefficient (dimensionless)
S = 0.0097 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =1.86 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.40 1.28 4.53 0.28 0.55 shallow
0.00 0.50 0.75 3.16 0.24 0.29 shallow
2.00 0.60 2.28 5.79 0.39 1.22 shallow
2.00 0.74 3.12 6.68 0.47 1.88 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.74 ft Depth O.K.
Velocity= 1.16 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.45 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-5 Drainage Area:1.88 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:718 ft Intensity:7.42 in/hr
Section Slope: 0.97 % Runoff Coeff: 0.20
Lining Type: Curled Wood Mat Discharge: 2.79 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =2.79 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0.0097 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =0.665 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 deep
2 0.60 2.28 5.79 0.39 1.224 deep
2 0.65 2.57 6.11 0.42 1.440 deep
2 0.70 2.87 6.43 0.45 1.677 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.70 ft
Velocity= 0.97 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.42 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-6 Drainage Area: 1.43 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 626 ft Intensity: 9.67 in/hr
Section Slope: 0.64 % Runoff Coeff: 0.20
Ret Class:D Discharge:2.77 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 2.77 cfs flow by Rational Method
n = 0.09 Grass Manning's Coefficient (dimensionless)
S = 0.0064 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =2.09 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.40 1.28 4.53 0.28 0.55 shallow
0.00 0.50 0.75 3.16 0.24 0.29 shallow
2.00 0.60 2.28 5.79 0.39 1.22 shallow
2.00 0.78 3.39 6.93 0.49 2.10 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.78 ft Depth O.K.
Velocity= 0.82 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.31 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-6 Drainage Area:1.43 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:626 ft Intensity:7.42 in/hr
Section Slope: 0.64 % Runoff Coeff: 0.20
Lining Type: Curled Wood Mat Discharge: 2.12 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =2.12 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0.0064 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =0.623 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 deep
2 0.60 2.28 5.79 0.39 1.224 deep
2 0.65 2.57 6.11 0.42 1.440 deep
2 0.43 1.41 4.72 0.30 0.634 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.43 ft
Velocity= 1.50 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 0.17 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-7 Drainage Area: 1.44 ac
Sta from:Design Fequency: 10 yrs
Sta to:Time of Conc: 5 min
Section Length: 371 ft Intensity: 9.67 in/hr
Section Slope: 8.09 % Runoff Coeff: 0.20
Ret Class:D Discharge:2.78 cfs
Permissible Velocity: 5.50 fps
Allowable Depth:1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp = 2.78 cfs flow by Rational Method
n = 0.088 Grass Manning's Coefficient (dimensionless)
S = 0.0809 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =0.58 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2.00 0.40 1.28 4.53 0.28 0.55 shallow
0.00 0.50 0.75 3.16 0.24 0.29 shallow
2.00 0.60 2.28 5.79 0.39 1.22 deep
2.00 0.41 1.32 4.59 0.29 0.58 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.41 ft Depth O.K.
Velocity= 2.10 fps Vel. O.K.
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 2.07 lb/sq-ft
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1.0 ft top width, W =8.0 ft
Permanent Channel Lining:Grass
(REF: Malcom, 1991)
PERMANENT LINING - Permissible Velocity and Capacity
Page 1
LINED CHANNEL DATE DESIGN PHASE
DESIGN 05-09-23 SD / /
PROJECT NAME PROJECT NO DD / /
Olsen Park 21-140 CD / x /
LOCATION BY REV / /
Wilmington, NC PL OTHER / /
CHECKED BY (SPECIFY)
PL
Channel No:CHANNEL-7 Drainage Area:1.44 ac
Sta from: 0 Design Fequency: 2 yrs
Sta to: 0 Time of Conc: 5 min
Section Length:371 ft Intensity:7.42 in/hr
Section Slope: 8.09 % Runoff Coeff: 0.20
Lining Type: Curled Wood Mat Discharge: 2.14 cfs
Permissible Shear: 1.55 lb/sf
Channel Depth: 1.00 ft
Swale sizing method done by manipulation of Manning's Equation to find the depth
of flow that matches the known flow conditions. Performed by trial and error.
INPUT DATA
Qp =2.14 cfs flow by Rational Method
n = 0.035 Manning's Coefficient (dimensionless)
S = 0.0809 ft/ft longitudinal slope (ft of fall per ft of run)
Zreq =0.176 quantity to equate to Zav
M = 3 :1 side slope of channel (ft of run : 1 ft of rise)
NORMAL DEPTH AND VELOCITY
B D A P R Zav Remark
2 0.50 1.75 5.16 0.34 0.851 deep
2 0.60 2.28 5.79 0.39 1.224 deep
2 0.65 2.57 6.11 0.42 1.440 deep
2 0.22 0.59 3.39 0.17 0.181 OK
B = bottom width of trapezoidal channel
D = normal depth of flow
A = cross-sectional area of flow
P = wetted perimeter of the channel
R = hydraulic radius of the channel
0
Normal Depth, D = 0.22 ft
Velocity= 3.65 fps
SHEAR STRESS
T = yds = shear stress in lb/sq-ft
Y = unit weight of water, 62.4 lb/cu-ft
D = normal depth of flow in ft
S = longitudinal slope in ft/ft
shear stress, T = 1.11 lb/sq-ft Temp Liner O.K.
FINAL CHANNEL LINING DIMENSIONS
B = 2 ft side slopes, M =3 :1
D = 1 ft top width, W =8.0 ft
Line Channel with:Curled Wood Mat
(REF: Malcom, 1991)
TEMPORARY LINING - Permissible Shear
Page 2
Maps
Deed