PROJECT #: CALCULATED BY: DATE:
SCOUR HOLE 1A-1
Design Parameters
W_{0} Max Width of Pipe/Culvert 15 in
Q Flow: 25-yr Storm Discharge 0.65 cfs
TW Tail water from 2 year storm 1.59 ft
Rip Rap Stone Size Calculations
q Unit Discharge = Q/W_{0} 0.52 cfs per foot
Option 1 if Scour Hole Depth, y = 1/2D0 7.5 in
Apron Dimension Calculations
Minimum Bottom Width W1 = 2 W0 2.50 ft
Minimum Bottom Length L1 = 3 D0 3.75 ft
Minimum Top Width (max side slope of 3:1), 6.25 ft
Minimum Top Length (max side slope of 3:1) 7.50 ft
Median Stone d50 = (0.0125q1.33)/TW 6 in
Apron Thickness, TH = 2 × d50 12 in
Option 2 if Scour Hole Depth, y = D0 15 in
Apron Dimension Calculations
Minimum Bottom Width W1 = 2 W0 2.50 ft
Minimum Bottom Length L1 = 3 D0 3.75 ft
Minimum Top Width (max side slope of 3:1), 10.00 ft
Minimum Top Length (max side slope of 3:1) 11.25 ft
Median Stone d50 = (0.0082q1.33)/TW 4 in
Apron Thickness, TH = $ 2x $ d50 8 in
[F31 [F2]