Table 1. TSS Reduction Standards
| |
---|---|
Development Type
|
TSS Reduction
|
New development
|
80%
|
In-fill development
|
80%
|
Redevelopment
|
40% of load from parking areas and roads
|
Table 2. Maximum Predevelopment Runoff Curve Numbers
| ||||
---|---|---|---|---|
Runoff Curve Number
|
Hydrologic Soil Group
| |||
A
|
B
|
C
|
D
| |
Woodland
|
30
|
55
|
70
|
77
|
Grassland
|
39
|
61
|
71
|
78
|
Cropland
|
55
|
69
|
78
|
83
|
Table 3. Atlas 14 Precipitation Depths
| |
---|---|
24-Hour Storm Event
|
Precipitation Depths
(inches)
|
1-year
|
2.46
|
2-year
|
2.82
|
Table 4. Separation Distances and Soil Characteristics
| ||
---|---|---|
Source Area
|
Separation Distance
|
Soil Characteristics
|
Industrial, commercial, institutional parking lots and roads
|
5 feet or more
|
Filtering layer
|
Residential arterial roads
|
5 feet or more
|
Filtering layer
|
Roofs draining to subsurface infiltration practices
|
1 foot or more
|
Native or engineered soil with particles finer than coarse sand
|
Roofs draining to surface infiltration practices
|
Not applicable
|
Not applicable
|
All other impervious source areas
|
3 feet or more
|
Filtering layer
|