Design Guide
Runoff Collection/Discharge Bay
|
Step
|
Description
|
Method/Design Parameter
|
Equation |
Variables |
Value
|
Units |
| 3.1 |
Establish collection point where
runoff exits collection area to external basin |
Establish collection bay dimension
(length and width) to accommodate screens and drainpipe area for
integrated storage basin scenario. Minimum width of collection/discharge
bay opening to be 1.0 m. Collection bay height equal to containment
wall height. Only screening of coarse materials may be done. |
|
Width of collection/discharge bay |
|
m |
| |
Length of collection/discharge
bay |
|
m |
| |
Height of collection/discharge bay |
|
m |
| 3.2 |
Establish screen configuration
(if applicable) |
Determine size of screens
based on the opening dimension of the collection/discharge bay.
Install handle on top of screen to ease removal. Allow for c-channel
width when establishing screen width. |
|
Screen width |
|
m |
| |
Screen height |
|
m |
| 3.3 |
Select screen material (if applicable) |
Select material for construction of
coarse, medium and fine screen. |
|
Material |
|
|
| 1. Coarse-vertical spacing of approx.
25 mm (1 in.) |
|
Material |
|
|
| 2. Medium-vertical spacing of approx.
10 mm (3/8 in.) |
|
Material |
|
|
| 3. Fine-vertical spacing of approx.
3.1 mm (1/8 in.) |
|
Material |
|
|
|
3.4
|
Calculate orifice plate opening
based on orifice discharge capacity
|
1. Integrated Storage — select
discharge rate from Step 2.2.4. |
A = Q/[(C)(2gh)0.5] |
A = orifice opening area |
|
m2 |
| Q = discharge rate from integrated
storage |
|
m3/s |
| C = orifice constant |
0.61 |
|
| g = acceleration due to gravity |
9.8 |
m/s2 |
| h = head on orifice |
|
m |
| D = (4A/3.14)0.5 |
D = orifice diameter |
|
m |
| A = orifice opening area |
|
m2 |
| 2. External Storage — select
discharge rate from Step 2.3.4. |
A = Q/[(C)(2gh)0.5] |
A = orifice opening area |
|
m2 |
| Q = discharge rate from external storage |
|
m3/s |
| C = orifice constant |
0.61 |
|
| g = acceleration due to gravity |
9.8 |
m/s2 |
| h = head on orifice |
|
m |
| D=(4A/3.14)0.5 |
D = orifice diameter |
|
m |
| A = orifice opening area |
|
m2 |
| 3.5 |
Calculate diameter of drainpipe |
Select drainpipe to accommodate two
times the discharge rate of the external storage/settling basin
from Step 2.2.4 or 2.3.4. |
A = 2Q/[(C)(2gh)0.5] |
A = area of drainpipe |
|
m2 |
| Q = discharge rate from external storage |
|
m3/s |
| C = orifice constant |
0.61 |
|
| g = acceleration due to gravity |
9.8 |
m/s2 |
| h = head on orifice |
|
m |
| D=(4A/3.14)05 |
D = diameter of drainpipe |
|
m |
| A = area of drainpipe |
|
m2 |
| 3.6 |
Determine the minimum open area
in the perforated riser pipe |
Use Equation 3.7 to determine the
size of the open slot or hole area in the perforated riser pipe.
Increase the open area by 25%. |
A= 1.25Q/[(C) × (2gh)0.5] |
A= minimum slot or hole area |
|
m2 |
| Q = orifice discharge capacity |
|
m3/s |
| C = orifice constant |
0.61 |
|
| g = acceleration due to gravity |
9.8 |
m/s2 |
| h = head on orifice |
|
m |
| Choose individual slot size. |
|
L = slot length |
|
m |
| W = slot width |
|
m |
| Calculate individual slot area. |
Individual slot area = L × W |
|
|
m2 |
| OR |
| Choose individual hole diameter. |
|
D = individual hole diameter |
|
m |
| Calculate individual hole area. |
Individual hole area = (3.14)D2/4 |
|
|
m2 |
| Calculate number of slots or individual
holes in perforated riser pipe. |
No. of slots required = A/individual slot area |
|
|
|
| OR |
|
|
|
| No. of holes required = A/individual hole area |
|
|
|
| 3.7 |
Select Sump |
Select an appropriate size and type
of sump. Maximum water depth in sump should be below frost line.
Total sump depth equals frost-line depth plus depth to accommodate
volume required by pump or siphon. |
|
Sump volume (siphon/pump volume) |
|
m3 |
| Establish sump volume and dimensions. |
|
Sump length |
|
m |
| Sump width |
|
m |
| Sump depth |
|
m |
| Material of sump |
|
|
| 3.8 |
Siphon Device
|
Contact a siphon device manufacturer
to select the most appropriate gravity flow mechanism in the sump.
|
|
|
|
|
| Note: Contact sump, siphon/pump manufacturer
for sump volume recommendations |
|
|
|
|
|
