SW1080103_401 Certification Application_20080605

Permit
(to be provided by DWO)
®�� 20F W A TFgO
O G
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, tilled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name
Hillandale Elementary School
Contact person
Kenny Draffen PE
Phone number
704-841-2588
Date
2/12/2008
Drainage area number
1
II: DESIGN INFORMATION
Site Characteristics
Drainage area
537,581
f?
Impervious area
297,791
ft2
impervious
55.3946289
Design rainfall depth
1.0
in
Storage Volume: Non -SR Waters
Minimum volume required
24,413
113
Volume provided
25,671
If
Storage Volume: SR Waters
1-yr, 24-hr runoff depth
in
Pre -development 1-yr, 24-hr runoff
If
Post -development 1-yr, 24-hr runoff
ff3
Minimum volume required
rya
Volume provided
It
Peak Flow Calculations
Is pre/post control of the 1-yr 24-hr peak flow required?
Y
(Y or N)
1-yr, 24-hr rainfall depth
3.3
in
Rational C, pre -development
0.4
(unitless)
Rational C, post -development
0.6
(unitless)
Rainfall intensity:l-yr, 24-hr storm
0.1
in/hr
Pre -development l-yr, 24-hr peak flow
0.7
ft3/sec
Post -development 1-yr, 24-hr peak flow
1.0
ft3/sec
Pre/Post 1-yr, 24-hr peak flow control
0.3
ft3/sec
Basin Elevations
Basin bottom elevation
2169.00
It
Sediment cleanout elevation
2170.00
it
Bottom of shelf elevation
2175.50
It
Permanent pool elevation
2176.00
it
Top of shelf elevation
21M.50
It
Temporary pool elevation
2177.64
it
Volume and Surface Area Calculations
SAIDA ratio
2.40
(unitless)
Surface area at the bottom of shelf
10262.00
it'
Volume at the bottom of shelf
35146.00
it
Permanent pool, surface area required
13,068
It
Permanent pool, surface area provided
13,137
ft2
Permanent pool volume
40,975
ft3
Average depth for SA/DA tables
3.119053056
ft
Surface area at the top of shelf
15277
1?
Volume at the top of shelf
48065
ft3
OK
OK
Form SW401-Wet Detention Basin-Rev.3 Parts I. & II. Design Summary, Page 1 of 2

Permit
(to be provided by DWO)
Forebay volume
Forebay % of permanent pool volume
Temporary pool, surface area provided
Drawdown Calculations
Treatment volume drawdown time
Treatment volume discharge rate
Pre -development 1-yr, 24-hr discharge
Post -development 1-yr, 24-hr discharge
Additional Information
Diameter of orifice
Design TSS removal
Basin side slopes
Vegetated shelf slope
Vegetated shelf width
Length of flowpath to width ratio
Length to width ratio
Trash rack for overflow & orifice?
Freeboard provided
Vegetated filter provided?
Recorded drainage easement provided?
Capures all runoff at ultimate build -out?
Drain mechanism for maintenance or emergencies
7,651
ft'
19
%
OK
17,057
it
2.44
days
OK
0.12
ft3/s
0.70
ft3/s
OK
0.12
ft3/s
OK
2.50
in
85
%
3
:1
10
:1
10
it
4
:1
1.5
:1
Y
(Y or N)
it
1
Y
(Y or N)
Y
(Y or N)
Y
(Y or N)
OK
OK
OK
OK
OK
OK
OK
OK
OK
OK
Form SW401-Wet Detention Basin-Rev.3 Parts I. & II. Design Summary, Page 2 of 2

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o
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
11. PROJECT INFORMATION
Project name Hillandale Elementary School
Contact name Kenny Draffen PE
Phone number 704-841-2588
Date February 12, 2008
Drainage area number 1
II. DESIGN INFORMATION
For Level Spreaders Receiving Flow From a BMP
Type of BMP Wet Detention
Drawdown flow from the BM 0.12 cfs
For Level Spreaders Receiving Flow from the Drainage Area
Do not complete this section of the
worksheet.
Drainage area
if
Impervious surface area
if
Percent impervious
Do not complete this section of the
worksheet.
Rational C coefficient
Do not complete this section of the
worksheet.
Peak flow from the 1 inmr storm
cis
Do not complete this section of the
worksheet.
Time of concentration
min
Rainfall intensity, 10-yr storm
inlhr
Do not complete this section of the
worksheet.
Peak flow from the 10-yr storm
cis
Do not complete this section of the
worksheet.
Where Does the Level Spreader Discharge?
To a bioretention cell? N (Y or N)
To a wetland? N (Y or N)
To a filter strip or riparian buffer? Y (Y or N) Please complete filter strip characterization below.
Other (specify)
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass 30 it
Width of dense ground cover 0 it
Width of wooded vegetation 0 it
Total width 30 it
Slope (from level lip to to top of bank) 2
Are any draws present? N (Y or N)
Level Spreader Design
Forebay surface area
500
sq it
Feet of level lip needed per cis
13
ft/cfs
Answer "Y" to one of the following:
Length based on the 1 inlhr storm?
N
(Y or N)
Length based on the 10-yr, 24-hr storm?
N
(Y or N)
Length based on the BMP discharge rate?
Y
(Y or N)
Design flow
0.12
cis
Is a bypass device provided?
N
(Y or N)
Length of the level lip
13
11
Are level spreaders in series?
N
(Y or N)
An
Cd3
A bypass device must be provided.
#VALUE!
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer- Rev .3 Pads 1. and 11. Design Summary, page 1 of 2

Bypass Channel Design (if applicable)
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Dimensions of the channel (see diagram below):
M
B
W
y
Peak velocity in the channel during the 10-yr, 24-hr storm
Channel lining material
M
(Y or N) Do not complete this section of the worksheet.
Do not complete this section of the worksheet.
Do not complete this section of the worksheet.
ft Do not complete this section of the worksheet.
ft Do not complete this section of the worksheet.
it Do not complete this section of the worksheet.
ft Do not complete this section of the worksheet.
cfs Do not complete this section of the worksheet.
Do not complete this section of the worksheet.
y
----------
M
i li i
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer- Rev .3 Parts I. and II. Design Summary, page 2 of

Permit Number:
(to be provided by DWO)
®�n O2QF W A TF9OG
NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM o
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must also be filled out, printed and submitted along with all of the required information.
Project name
Contact name
Phone number
Date
Drainage area number
Kenny Draffen PE
704-841-2588
21, 2008
School
II. DESIGN INFORMATION
Site Characteristics
Drainage area
12,016.00 rye
Impervious area
3,964.00 f?
Percent impervious
33.0% %
Design rainfall depth
5.60 inch
Peak Flow Calculations
10-yr storm runoff depth
5.60
in
1 0-yr storm intensity
2.32
in/hr
Post -development 10-yr storm peak flow
0.05
Wlsec
Velocity
Maximum non -erosive velocity (peak 10-year storm)
4.5011/sec
Soil characteristics (enter Y' below)
Sand/silt (easily erodible)
x
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
x
Bahiagrass
Kentucky bluegrass
Grass -legume mixture
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale:
N
(Y or N)
Maximum velocity
Side slopes
:1
Swale length
It
Option 2: Conveyance Swale, Seeking Pollutant Credit:
N
(Y or N)
Maximum velocity for 10-yr storm
ft/sec
Side slopes
:1
Swale length
It
Form SW401-Grassed Swale-Rev.3 Parts I and II. Project Design Summary, Page 1 of 2

Permit Number
(to be provided by DWO)
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal x
Parabolic
V-shaped
Width of the bottom of the swale 8.00 It
Width of the top of the swale 18.00 It
Additional Information
Is the Swale sized for all runoff from ultimate build -out?
Y (Y or N)
Insufficient sizing
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Y (Y or N)
Insufficient ROW location.
What is the distance from the bottom of the swale to the SHWT?
9.00 It
OK
What is the ground level elevation?
2,182.00 fmsl
What is the elevation of the bottom of the Swale?
2,181.00 fmsl
What is the SHWT elevation?
2,172.00 fmsl
What is the longitudinal slope of the Swale?
2,00 %
OK
What is the depth of freeboard?
0.86 It
OK
Form SW401-Grassed Swale-Rev.3 Parts I and 11. Project Design Summary, Page 2 of 2