SW6230104_Design Calculations_20230718 (2)

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L=J Post Office Box 789, Hillsborough, North Carolina 27278 t. Phone:[phone]
El Post Office Box 789, Hillsborough, North Carolina 27278
Faircloth �1, 4r` CONTACT US
SkimmeroF" `'
e i� (919) 732-1244
n HOME 0: TECHNICAL INFO L SKIMMER SIZING WW ORDER SKIMMER
STORMWATER SURFACE DRAIN p CONTACT
SKIMMERSIZING Home / Skimmer Sizing
ONLINE CALCULATORS
CALCULATE FAIRCLOTH SKIMMER® SIZE
Required Basin volume in cubic feet Days to Drain
8596 3
The required basin volume is the actual volume you intend Number of Days to drain is usually
to drain, not the provided or total volume which is often determined by local or state regulations.
larger. If a pool of water is to be maintained between Where there is no requirement 3 days is
storms, do not include that volume. In some cases a recommended. Keep in mind the quicker the
sediment basin may be larger than required because it will basin is to drain the larger the skimmer
be used as a permanent stormwater pond. required. In NC, assume 3 days to drain.
SKIMMER SIZE
2.0 inches

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ORIFICE DIAMETER
1.8 inches
BASIN VOLUME CALCULATOR
If you do not know the basin's volume but you do know the dimensions and depth of a
square or rectangular basin, use this calculator to estimate the volume.
Length Width
Top of water surface in
feet
Bottom dimensions in
feet
Depth in feet
ESTIMATED BASIN VOLUME
0 cubic feet
IMPORTANT!
The calculator does not take into consideration Common Sense. For example, if the
volume entered is even one cubic foot greater that the maximum calculated capacity of
a skimmer the next larger size will be given as the answer.
In reality, a reasonable judgment would be that the smaller size is adequate given the
room for error in the assumptions that go along with the design and sizing process.

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stops wnen the aasin is rum, wnicn may not ae the case (inflow may continue,
lengthening the drain time); or another rain event may occur before the basin drains.
Therefore it is recommended that the following flow capacities chart be used
together with the calculator.
FLOW CAPACITIES (IN FT 3 ) FOR THE FAIRCLOTH
SKIMMER®
Skimmer
1.5" 2" 2.5" 3" 4" 5" 6" 8"
size
24 hours 1,728 3,283 6,234 9,774 20,109 32,832 51,840 97,978
2 day 3,456 6,566 12,468 19,548 40,218 65,664 103,680 195,956
3 day 5,184 9,849 18,702 29,322 60,327 98,496 155,520 293,934
4 day 6,912 13,132 24,936 39,096 80,436 131,328 207,360 391,912
5 day 8,640 16,415 31,170 48,870 100,545 164,160 259,200 489,890
6 day 10,368 19,698 37,404 58,644 120,654 196,992 311,040 587,868
7 day 12,096 22,981 43,638 68,418 140,763 229,824 362,880 685,846
d TECHNICAL SIZING INSTRUCTIONS
Determining the Skimmer Size and the Required Orifice for the Faircloth Skimmer°Surface Drain(click here to
open document)
DETERMINING SKIMMER SIZE
• Eight sizes available, ranging from 11/2"for small sediment traps to 8"for very large
basins.
• Size refers to the maximum diameter of the inlet. For example, a 4" Faircloth
Skimmer®has a 4" maximum orifice size.
• Each Faircloth Skimmer®includes a plugand adjustable cutter for making an orifice
(hole) smaller than the inlet to customize the flow rate for the particular basin.

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head is different for each size skimmer.)
Also, the head may vary slightly when the skimmer is in use, plus or minus, depending upon
the depth of water and the position of the skimmer. The actual flow rate for the installed
skimmer may be slightly less than calculated, especially when the barrel has a flat or low
slope.
Any variation in flow rate is considered insignificant enough to appreciably affect the drain
time considering the number of variables involved. Therefore, the theoretical rates are
used to simplify the orifice sizing process.
The calculation is rounded to the nearest 10th of an inch because that is as close as the
cutter can be adjusted and the orifice cut.
Faircloth CONTACT INFO TECHNICAL
Skimmer � ��.'� � Address: DOCUMENTS
�� ,
Post Office Box Installation
789 Instructions
J. W. Faircloth & Son, Inc. is dedicated to Hillsborough,
promoting environmental responsibility byManuals
p g P Y North Carolina
developing, manufacturing, and distributing 27278 Cut Sheets
Faircloth Skimmer® surface drains for
dewatering sediment basins. Phone number: Drawings
919-732-1244 Certifications
ENGINEERS CLICK HERE and Approvals
Fax number:
919-732-1266 Frequently
Asked
Questions

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Christmas Dec 23-27, and New Years Jan 1-2. Got it!