Table 17.1
| |
---|---|
Exemptions and Submission Requirements
| |
New Impervious Area
(square feet)
|
Applicant Must Provide
|
0 to <5,000
|
Documentation of new impervious surfaces
|
5,000 and greater
|
Rate controls, volume controls and SWM site plan
|
NOTES:
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---|---|---|
1.
|
New impervious area since the date of adoption of this chapter.
| |
2.
|
Gravel in existing condition shall be considered pervious and
gravel in proposed condition shall be considered impervious.
|
Time of concentration = Tc
| |
---|---|
Tc = (T\0.6) * 60 (minutes)
| |
T = l0.8 (S + 1)0.7\1900Y5
|
Where:
| ||||
T
|
=
|
Lag time (hours).
| ||
l
|
=
|
Hydraulic length of watershed (feet).
| ||
Y
|
=
|
Average overland slope of watershed (percent).
| ||
S
|
=
|
Maximum retention in watershed as defined by: S = [(1,000/CN)
- 10].
| ||
CN
|
=
|
NRCS curve number for watershed.
|