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Drainage Inlets

Information listed below is from the FDOT Design Standards. U.S. Foundry steel grate catalog numbers are for AASHTO H-20 wheel loads, and pedestrian (non-traffic) loading.


Traffic Bearing Inlets

* Inside dimensions are the same for both cast-in-place and precast, except for inlet types J, S, & V which all have precast inside dimensions of 3′–3″ × 3′–10″.
Alt. B structure bottom (FDOT index 200) may be used with inlet types F, G, J, S, & V.
Do not use type J or V inlets where bicycle traffic is anticipated.
Type S inlet is for shoulder gutter applications.
Inlet
Type
FDOT
Index
Outside Dimensions * Inside
Dimensions
Max. Pipe Size Steel Grate #
Cast-In-Place Precast Short Long H-20 Non-Traf
F 233 3′–10″ × 5′–4″ 3′–6″ × 5′–0″ 2′–6″ × 4′–0″ 18″ 30″ 6631 6630
G 6′–2″ × 6′–4″ 4′–10″ × 5′–0″ 42″ 6661 6660
J 234 4′–3″ × 5′–4″ 4′–3″ × 4′–10″ 2′–11″ × 4′–0″ 24″ 30″ 6685 6652
S 220 6658 6652
V 221 6657 6651


Non-Traffic Bearing Inlets

* 18″ maximum where an 18″ pipe enters a 2′–0″ wall.
Inside dimensions are the same for both cast-in-place and precast.
Alt. B structure bottom (FDOT index 200) may be used with inlet types C, D, & E.
H(2) is type H inlet with 2 steel grates; H(4) is type H inlet with 4 steel grates.
Note: Although H-20 steel grate catalog numbers are listed for non-traffic bearing inlets, the use of these inlets in areas subject to heavy wheel loads is strongly discouraged.
Inlet
Type
FDOT
Index
Outside Dimensions Inside
Dimensions
Max. Pipe Size Steel Grate #
Cast-In-Place Precast Short Long H-20 Non-Traf
C 232 3′–4″ × 4′–5″ 3′–0″ × 4′–1″ 2′–0″ × 3′–1″ 18″ * 24″ 6611 6606
D 4′–5″ × 5′–5″ 4′–1″ × 5′–1″ 3′–1″ × 4′–1″ 24″ 36″ 6626 6607
E 4′–4″ × 5′–10″ 4′–0″ × 5′–6″ 3′–0″ × 4′–6″ 6616 6608
H(2) 4′–4″ × 7′–11″ 4′–0″ × 7′–7″ 3′–0″ × 6′–7″ 60″ or
2–24″
6621 6609
H(4) 4′–4″ × 10′–1″ 4′–0″ × 9′–9″ 3′–0″ × 8′–9″ 78″ or
2–30″
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Curb Inlets

* Hydraulic intake values do not represent hydraulic capacity, but are shown to compare inlets based on a 0.2% longitudinal slope, 2% cross slope, and a 90% efficiency factor.
FDOT
Index
Inlet
Type
Type
Curb/Gutter
Grade
Consideration
Width
(FT)
* Hydraulic
Intake (CFS)
210 1 E & F Continuous 13′ 4.1
2 Sag 20′ 9.0
3 Continuous 9′ 1.9
4 Sag 12′ 6.5
211 5 E & F Continuous 10.5′ 3.1
6 Sag 16′ 7.5
212 7 Separator I & II Continuous or Sag 5′ 4.4
213 8 Separator IV & V
214 9 D & F Continuous or Sag 0.5
215 10 0.3