HomeMy WebLinkAboutSW1160501_Supplement Calculations_20160601Permit No
(to be provided by DWQ)
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STORMWATER MANAGEMENT PERMIT APPLICATION FORM p
NCdENR 401 CERTIFICATION APPLICATION FORM
INFILTRATION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project Name
New Retail Store - Sapphire, NC
Contact Person
Derek Westfall, P.E.
Phone Number
770-988-0400
Basin bottom elevation
Date
06.01.2016
Storage elevation
Drainage Area Number
1
Storage Surface Area
2,325.00
II. DESIGN INFORMATION
Top elevation
3,069.75
Site Characteristics
Basin Bottom Dimensions
Drainage area
179,729.00
ftz
Impervious area
29,229.00
ftz
Percent impervious
16.26
%
Design rainfall depth
1.00
in
Peak Flow Calculations
1 -yr, 24 -hr rainfall depth
4.50
in
1 -yr, 24 -hr intensity
0.19
in/hr
Pre -development 1 -yr, 24 -hr discharge
3.44
ft3 /sec
Post -development 1 -yr, 24 -hr discharge
3.07
ft3 /sec
Pre/Post 1 -yr, 24 -hr peak flow control
-0.37
ft3 /sec
Storage Volume: Non -SA Waters
Minimum design volume required
2,325.00
ft3
Design volume provided
2,364.00
ft3 OK for non -SA waters
Storage Volume: SA Waters
1.5' runoff volume
ft3
Pre -development 1 -yr, 24 -hr runoff volume
ft3
Post -development 1 -yr, 24 -hr runoff volume
ft3
Minimum required volume
ft3
Volume provided
ft3
Soils Report Summary
Soil type
Fill/Silty Sand
Infiltration rate
5.00
in/hr
SHWT elevation
3,056.00
fmsl
Basin Design Parameters
Drawdown time
1.00
days
Basin side slopes
1.00
:1
Basin bottom elevation
3,063.00
fmsl
Storage elevation
3,063.00
fmsl
Storage Surface Area
2,325.00
ftz
Top elevation
3,069.75
fmsl
Basin Bottom Dimensions
Basin length
93.81
ft
Basin width
22.79
ft
Bottom Surface Area
2,137.93
ft
OK
Side Slopes are too steep, maximum 3:1
OK
Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I. & II. Design Summary, Page 1 of 2
Additional Information
Maximum runoff to each inlet to the basin?
Length of vegetative filter for overflow
Distance to structure
Distance from surface waters
Distance from water supply well(s)
Separation from impervious soil layer
Naturally occuring soil above shwt
Bottom covered with 4 -in of clean sand?
Proposed drainage easement provided?
Capures all runoff at ultimate build -out?
Bypass provided for larger storms?
Pretreatment device provided
Permit No
1.23
ac -in
OK
NA
ft
OK
NA
ft
OK
123.63
ft
OK
NA ft OK
7.00 ft OK
Y ft OK
N (Y or N) Must cover bottom with 4 -in of clean sand
N (Y or N) Need a recorded drainage easement
Y (Y or N) OK
Y (Y or N) OK
Y Isolator Row Provide
(to be provided by DWQ)
Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I. & II. Design Summary, Page 2 of 2