Inlet Spacing

Given: Pavement consists of two 10 ft. lanes with vertical curb. S_L = 2% S_T = 2%. Two foot gutter. Permissible spread on pavement 6 ft.

Step 1

Spread: 6 + 2 = 8 ft.
Depth at curb = 8 x .02 = .016 ft.
Discharge for depth at curb Q = (.56 / N) Z (D ^8/3) S ^1/2 Solving equation by calculator Q = 1.9 cfs

Step 2

Determine capacity and spacing of first inlet on the slope. Pavement area which will produce equivalent discharge from equation: Q = CIA

Assume C = 0.9 and I = 4"/HR.
A = (Q / IC) = (1.85 / (4 x 0.9)) = 0.51 acres
Length to first inlet L = A / W = (.051 x 43560) / 22 = 1010 ft.

Step 3

Using Neenah inlet R-3246-A, Type C, K = 26
Substituting in the formula Q = K D^5/3
Q = 26 x (.16)5/3 = 26 x .047 = 1.226 CFS
By-pass 1.85 - 1.23 = 0.62 CFS

Step 4

Length to next inlet: Q / ICW = (1.23 x 43560) / (4 x 0.9 x 22) = 676 ft.

Solution

PROFILE

Station	Q Gutter	Depth Gutter	Q Grate	Q Bypass	Spread on Pavement
10 + 10	1.85 cfs	0.16'	1.23 cfs	0.62 cfs	6.0' + 2' gutter
10 + 60	0.62+ cfs	0.11'	N/A	N/A	3.5' + 2' gutter
16 + 86	1.85 cfs	0.16'	1.23 cfs	0.62 cfs	6.0' + 2' gutter
23 + 62	1.85 cfs	0.16'	1.23 cfs	0.62 cfs	6.0' + 2' gutter

For additional information regarding Neenah Inlet Grate Capacities, please contact Steven Akkala P.E., at (920) 729.3653 or email at steve.akkala@neenahenterprises.com.

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Inlet Spacing

Step 1

Step 2

Step 3

Step 4

Solution

Engineering Tools

Neenah Enterprises - Industrial

Neenah Foundry - Municipal