HomeMy WebLinkAboutWPO202200038 Calculations 2022-09-14 (21)1992
TEMPORARY SEDIMENT BASIN DESIGN DATA SHEET
(with or without an emergency spillway)
Project Breezy Hill
Basin # 2 Location
Total area draining to basin: 8.23 acres.
Basin Volume Desien
Wet Storage:
3.14
1. Minimum required volume = 67 cu. yds. x Total Drainage Area (acres).
67 cu. yds. x 8.23 acres = 551 cu. yds.
2. Available basin volume = 551 cu. yds. at elevation 348.30 (From
storage - elevation curve)
3. Excavate cu. yds. to obtain required volume*.
* Elevation corresponding to required volume = invert of the dewatering
orifice.
4. Available volume before cleanout required.
33 cu. yds. x 8.23 acres = 272 cu. yds.
5. Elevation corresponding to cleanout level = 347.2
(From Storage - Elevation Curve)
6. Distance from invert of the dewatering orifice to cleanout level = 1.10 ft.
(Min. = 1.0 ft.)
Dry Storage:
7. Minimum required volume = 67 cu. yds. x Total Drainage Area (acres).
67 cu. yds. x 8.23 acres = 551 cu. yds.
1992 3.14
8. Total available basin volume at crest of riser* = 1,103 cu. yds. at
elevation 350.19 . (From Storage - Elevation Curve)
* Minimum = 134 cu. yds./acre of total drainage area.
9. Diameter of dewatering orifice = 4 in.
10. Diameter of flexible tubing = 6 in. (diameter of dewatering orifice
plus 2 inches).
Preliminary Design Elevations,
11. Crest of Riser = 350.00
Top of Dam = 353.00
Design High Water = _
Upstream Toe of Dam =
Basin Shane
350.89
346.00
12. Length of Flow L =
Effective Width We
If > 2, baffles are not required
If < 2, baffles are required _
Runoff
13. Q = 10.23
z cfs (From Chapter P 5 )
14. Q = 16.65
zs cfs (From Chapter P 5 )
Principal SDillwav Design
15. With emergency spillway, required spillway capacity QP = Qz = cfs.
(riser and barrel)
Without emergency spillway, required spillway capacity QP = Q25 = 16.65 cfs.
(riser and barrel)
1992 3.14
16. With emergency spillway:
Assumed available head (h) = ft. (Using QZ)
It = Crest of Emergency Spillway Elevation - Crest of Riser Elevation
Without emergency spillway:
Assumed available head (h) = 2.11 ft. (Using Q25)
h = Design High Water Elevation - Crest of Riser Elevation
17. Riser diameter (Dr) = 36 in. Actual head (h) = 2.11 ft.
(From Plate 3.14-8.)
Note: Avoid orifice flow conditions.
18. Barrel length (1) = 70 ft.
Head (H) on barrel through embankment = 13 ft.
(From Plate 3.14-7).
19. Barrel diameter = 18 in.
(From Plate 3.14-B [concrete pipe] or Plate 3.14-A [corrugated pipe]).
20. Trash rack and anti -vortex device
Diameter = 54 inches.
Height = 17 inches.
(From Table 3.14-D).
Emergencv SDillwav Design
21. Required spillway capacity Qe = Qu - Qp = cfs.
22. Bottom width (b) = ft.; the slope of the exit channel (s) _
ft./foot; and the minimum length of the exit channel (x) _
ft.
(From Table 3.14-C).
1992 3.14
Anti -Seep Collar Design
23. Depth of water at principal spillway crest (Y) _ _ ft.
Slope of upstream face of embankment (Z) _ :1.
Slope of principal spillway barrel (Sb) _ %
Length of barrel in saturated zone (LS) = ft.
24. Number of collars required = dimensions =
(from Plate 3.14-12).
Final Design Elevations
25. Top of Dam = 353.00
Design High Water = 350.89
Emergency Spillway Crest = N/A
Principal Spillway Crest = 350.00
Dewatering Orifice Invert = 348.30
Cleanout Elevation = 347.2
Elevation of Upstream Toe of Dam
or Excavated Bottom of "Wet Storage 340
Area" (if excavation was performed) _