SW6231002_Design Calculations_20240805 (2)

Velocity Dissipator Design Calculations
Per NC Erosion&Sediment Control Planning&Design Manual %/ W it h e rs R a ve n e l
1 Our People.Your Success.
Project: Serenity Phase 8&9
Project#: 2190647 115 MacKenan Drive I Cary,NC 27511
By: WithersRavenel t:919.469.3340 I f:919.467.6008
Date: 2024-05-02 www.withersravenel.com I License No.F-1479
Revisions: Asheville I Cary I Charlotte I Greensboro I Pittsboro I Raleigh I Southern Pines I Wilmington
VELOCITY DISSIPATOR DESIGN SUMMARY
OUTLET PIPE LENGTH WIDTH WIDTH STONE MIN.
Q10 SLOPE VELOCITY ZONE TYPE
(Do) (La) (W1) (W2) CLASS DEPTH
(IN) (CFS) (%) (FPS) (Figure 8.06c) (Figure 8.06d) (FT) (FT) (FT) (IN)
600-HW 24 15.87 5.17 13.07 3 OVERLAND 8 6 10.0 1 24
614-HW 30 22.16 3.00 13.34 3 OVERLAND 10 7.5 12.5 1 24
700-HW 24 14.56 3.90 13.42 3 OVERLAND 8 6 10 1 24
715-HW 36 55.87 3.70 18.49 5 OVERLAND 15 9 18 2 36
800-HW 24 --7-9.08 1.91 2.89 2 OVERLAND 6 6 8 B 18
809-HW 24 16.72 2.30 6.03 3 OVERLAND 8 6 10 1 24
900-HW 36 49.20 1.14 5.11 3 OVERLAND 12 9 15 1 24
1100-HW 36 36.77 1.44 5.20 3 OVERLAND 12 9 15 1 24
1000-HW 42 45.43 0.90 4.74 3 OVERLAND 14 10.5 17.5 1 24
i
NOTES
1.All dissipators shall have filter fabric underliners; NCDOT Standard Specification Section 1056,or approved
equivalent
2.Outlet and downstream widths shall be installed as shown in chart unless discharging into a channel,where
the riprap shall be placed from top of bank to top of bank.
3. Design based on Section 8.06, Design of Riprap Outlet Protection,from the NC Erosion&Sediment Control
Planning& Design Manual.

Velocity Dissipator Design Calculations
Per NC Erosion&Sediment Control Planning&Design Manual 1/ W i t h e rs R a ve n e l
1/ Our People.Your Success.
Project: Serenity Phase 8&9
Project#: 2190647 115 MacKenan Drive I Cary,NC 27511
By: WithersRavenel t:919.469.3340 I f:919.467.6008
Date: 2024-05-02 www.withersravenel.com I License No.F-1479
Revisions: Asheville I Cary I Charlotte I Greensboro I Pittsboro I Raleigh I Southern Pines I Wilmington
25 ;I; 1 ,
} t;
lei ;
\: is '
i
USE VELOCITY AND PIPE
DIAMETER TO SELECT ZONE a 15 1 a. ; , e ; ;
" 5 }
i
V iI : i ; 'O10 ; .}•;
k\c,
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0 x' a(ar 4r c 1 I I
0' 5' Ur iS 20' 25
DIAMETER (Ft.)
Figure 8.06c
RIPRAP SPECIFICATIONS
ZONE APRON MATERIAL STONE DIAMETER(in) APRON LENGTH(x Do)* MIN.DEPTH(in) CLASS
CHANNEL OVERLAND CHANNEL OVERLAND
1 Stone Filling(Fine) 3" 4 3 9 12 A
2 Stone Filling(Light) 6" 6 3 12 18 B
3 Stone Filling(Medium) 13" 8 4 18 24 1
4 Stone Filling(Heavy) 23" 8 4 30 36 1
5 Stone Filling(Heavy) 23" 10 5 30 36 2
6 Stone Filling(Heavy) 23" 10 6 30 36 2
Special Study Required(Energy Dissipators,Stilling
Basins,or Larger Size Stone STUDY STUDY STUDY STUDY STUDY
7*MULTIPLY BY PIPE DIAMETER Figure 8.06d
T LENGTH OF APRON W1 3 0 ;------T
W TO PROTECT TO PREVENT SCOUR
NAPRON MATERIAL CULVERT HOLE USE L2 ALWAYS Outlet W2. Do + La
L2
LI pipe
• • diameter(De)
1 STONE FILLING(FINE) CL.A 3 X D, 4 x D, La —«
" T ilwater < 0.5D0
2 STONE FILLING(LIGHT) CL.B 3 X D, 6 x D.
3 •STONE FILLING(MEDIUM)CL.1 4 X D, 8 x D, Ll -Overland
4 STONE FILLING(HEAVY) CL.1 4 X D, 8 x D, W1= 3D
o fi
5 STONE FILLING(HEAVY) CL.2 5 X D, t0 x D, _
• — — Outlet IW2= 00 0. a4L
6 .STONE FILLING(HEAVY) CL.2 6 X D0 I 10 x D. pipe 1 11
diameter(Do)1,,— La .1
7 .SPECIAL STUDY REQUIRED(ENERGY DISSIPATORS.STILLING
BASIN OR LARGER SIZE STONE). q Tailrwt 1-3 ,.5D0
r
Figure 8.06d
L2-Channel