D DYNAMIC ENGINEERING

Preformed Scour Hole Design

Project:Proposed Office Building
Job #:3342-99-007
Location:Jackson, NJ
Design Storm:25-Year
Computed By:NC
Checked By:
Date:2/10/2026

Discharge not in Basin, Therefore Tailwater is less than 0.5 x Do

Discharge Point IDPOI AREA WEST
Q (25-yr storm cfs)0.7
Inside Height of Outlet Culvert, Do (in)15
Inside Height of Outlet Culvert, Do (ft)1.3
Tailwater (ft), TW0.25
Bottom Length of Scour Hole, L1=3 Do (ft)3.75
Width of Culvert, Wo (in)15
Width of Culvert, Wo (ft)1.3
Bottom Width of Scour Hole, W1=2 Wo (ft)2.50

When using Y = (.5)(Do):

Where Y = .5 Do, Y(ft)0.625
Median Stone Diameter*, D50 (ft)0.02
Overall Length of Scour Hole, L2 (ft)7.50
Overall Width of Scour Hole, W2 (ft)6.25

When using Y = (D0):

Where Y = Do, Y(ft)1.250
Median Stone Diameter*, D50 (ft)0.02
Overall Length of Scour Hole, L2 (ft)11.25
Overall Width of Scour Hole, W2 (ft)10.00

Use D50 equal to 6 inches

Use D50 equal to 6 inches

Equations used: Tw=0.2*Do (If Tw cannot be computed) Where Y=1/2 Do D50=(0.0125/Tw)*(q^1.33) Where Y=Do D50=(0.0082/Tw)*(q^1.33)

Notes: ___

  1. The use of scour holes shall comply with county or local ordinances which would restrict the use of such devices due to the possible problems with mosquito breeding.
  2. No bends or curves at the intersection of the conduit and apron or scour hole will be permitted.
  3. There shall be no overfall from the end of the apron to the receiving material.
  4. The thickness of the riprap lining, filter, and quality shall meet the requirements in the Riprap Standard Section of the Standards for Soil Erosion Control in New Jersey.
  5. Use a D50 of 6 inches minimum.