Site Size
(acres)
|
Number of Test Pits
| |
---|---|---|
Initial 5
|
1 per acre, minimum of 2
| |
More than 5 to 20
|
5 plus 1 per 2 acres beyond the initial 5 acres
| |
More than 20
|
13 plus 1 per 5 acres beyond the initial 20
acres
|
Class of Dam
|
Drainage Area
|
Top of Embankment
| |
---|---|---|---|
a
|
Less than 320 acres
|
1 foot above maximum water surface elevation
for emergency spillway storm
| |
Greater than 320 acres
|
2 feet above maximum water surface elevation
for emergency spillway storm
| ||
b
|
Less than 150 acres
|
1 foot above maximum water surface elevation
for emergency spillway storm
| |
Greater than 150 acres
|
2 feet above maximum water surface elevation
for emergency spillway storm
| ||
c
|
Less than 150 acres
|
2 feet above maximum water surface elevation
| |
Greater than 150 acres
|
Special treatment. Criteria established for
each individual case
|
Description of Area
|
Run-Off Coefficient (C)
| ||
---|---|---|---|
Residential
| |||
2-acre single-family detached lots
|
0.40
| ||
1-acre single-family detached lots
|
0.46
| ||
1/2-acre single-family detached lots
|
0.50
| ||
1/4-acre single-family detached lots
|
0.56
| ||
Two-family and multifamily
|
0.70
| ||
Commercial
|
0.75
| ||
Industrial
|
0.80
| ||
Parks and cemeteries
|
0.38
| ||
Unimproved
|
0.35
| ||
Where the Table is not applicable the following
factors may be used:
| |||
Roofs and all impervious surfaces
|
0.90
| ||
All other surfaces except forest
|
0.40
| ||
Forest
|
0.30
|
Storm Frequency (years)
|
Factors
| |
---|---|---|
10 and less
|
1.0
| |
25
|
1.1
| |
50
|
1.2
|
Table 2
Type M or S Inlet Capacities (in Swale)
| ||||||
---|---|---|---|---|---|---|
Back Slope
| ||||||
Grade
|
2:1
|
4:1
|
6:1
|
12:1
|
Dike
| |
1.0
|
3.2
|
3.6
|
3.9
|
4.1
|
9.1
| |
2.0
|
3.5
|
3.5
|
3.5
|
3.7
|
8.3
| |
3.0
|
2.5
|
2.8
|
3.5
|
3.5
|
7.4
| |
4.0
|
1.6
|
2.0
|
3.4
|
3.2
|
6.4
| |
5.0
|
1.6
|
2.0
|
3.5
|
3.0
|
6.3
| |
6.0
|
1.6
|
2.0
|
3.3
|
2.8
|
6.1
| |
7.0
|
1.5
|
2.0
|
3.0
|
2.6
|
6.0
| |
8.0
|
1.5
|
2.0
|
2.8
|
2.4
|
5.8
|
H-C
|
Historic Commercial
| |
C-1
|
Commercial Neighborhood Shopping
| |
R-2
|
Residential Medium Density
| |
R-4
|
Residential Multiple Family High Density
|