Design Guide
Infiltration Area
|
Step
|
Description
|
Method/Design Parameter
|
Equation |
Variables |
Value
|
Units |
Example
|
| 6.1 |
Determine minimum infiltration area
required based on saturated hydraulic conductivity (Stage 1) |
Determine the saturated hydraulic
conductivity for the infiltration area soil |
Minimum infiltration area = target
flow rate (Step 4.5) saturated hydraulic conductivity y |
In-situ determination of saturated
hydraulic conductivity required |
|
m2 |
|
| 6.2 |
Determine minimum infiltration
area required based on liquid loading (Stage 2) |
Use Table 3.2 to obtain
highest normal monthly precipitation for closest station |
|
Maximum allowable liquid
loading is 5 cm/week including rainfall |
|
m/
month
|
|
Calculate highest normal weekly precipitation
(highest normal monthly precipitation/4)
|
|
Closest rainfall station is provided
in Table 3.3 |
|
m/
week
|
|
| Calculate outside paved
yard weekly runoff volume. |
|
Multiply the paved yard
area by the highest normal weekly precipitation |
|
m3 |
|
| Calculate limiting precipitation amount per week
on VFS. |
|
The limiting precipitation amount
per week is [5 cm minus highest normal weekly precipitation] |
|
m |
|
| Calculate minimum VFS area required. |
|
The yard weekly runoff
volume is divided by the limiting precipitation amount per week
on VFS |
|
m2 |
|
| 6.3 |
Determine minimum infiltration
area from Stage 1 (Step 6.1) and Stage 2 (Step 6.2) |
Select larger infiltration
area from Step 6.1 and Step 6.2. |
|
|
|
m2 |
|
| 6.4 |
Determine minimum length of infiltration
area |
Use Table 3.4 and VFS slope. |
|
|
|
m |
|
| 6.5 |
Determine minimum width of infiltration
area |
Use Equation 3.10. |
|
Flow depth is 0.0127 m and flow velocity
is found in Table 3.4 |
|
m |
|
| 6.6 |
Calculate actual infiltration area
dimensions |
Select largest infiltration area from
Stage 1 (Step 6.1) or Stage 2 (Step 6.2). |
|
Minimum length of infiltration area
comes from Step 6.4 (final width must be equal to or greater than
distance calculated in Step 6.5) |
|
m2 |
|
| 6.7 |
Determine final dimensions of infiltration
area |
See Step 6.6 for final dimensions
of infiltration area. |
|
Final infiltration area dimensions |
L =
W =
A =
|
m
m
m2
|
|
