SW8060660_COMPLIANCE_20060908 (2)

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW �l0(ND
DOC TYPE
❑CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
11 COMPLIANCE EVALUATION INSPECTION
DOC DATEi2/771/o(9gl2g'
WYYMMDD

'i
Permit No.
(to be proviried 6y D4VQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This forrrt may be photocopsd far use as art original
DWQ Stormwater Management Plan Review:
A complete stormwater management plan submittal includes an application form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details.
I. PROJECT INFORMATION
Project Name: � ,c��5 C1r\5e Ck.J6Vv se. c-4 (&,n-koxvice Fc2tt;-�d
Contact Person: e"-&\0A C-emvo� Phone Number: (LIM Z8"7- 1g63
For projects with multiple basins, specify which basin this worksheet applies to: SLj Pond
4r 2-
elevations
Basin Bottom Elevation
43.5
ft.
(floor of the basin.)
Permanent Pool Elevation
4F9.5
ft.
(elevation of the orifice)
Temporary Pool Elevation
SO.O
ft.
(elevation of the discharge structure overflow)
areas
Permanent Pool Surface Area
S!o 4S5
sq. ft.
(water sinface area at the orifice elevation)
Drainage Area
.79B4
ac.
(on -site and off=site drainage to the basin.)
Impervious Area
yil z
ac.
(on -,site and off -site drainage to the basin.)
volitrnes
Permanent Pool Volume Z35,a37- cu. ft. (combined volume of main basin crud forebay)
Temporary Pool Volume ZO, 941 cu. ft. (volunne detained above the permanent pool)
Forebay Volume 5�,3`i4i cu. ft. (appraeimotely 20% of total volume)
Other parameters
SA/DA] l .7-304 (surface area to drainage arect ratio from DWQ table)
Diameter of Orifice i.s in. (2 to S clay temporary pool drab, -down required)
Design Rainfall 1 in.
Design TSS Removal 2 % (mininunn 85% required)
Form SWU-tot Rev 3.99 Page 1 of 4

Footnotes:
t When using the Division SAIDA tables, the correct SAIDA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
2 In (lie 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines desiun requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an ,tgc:zt in the Stortnwater Management Permit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
b. The forebay volume is approximately equal to 20% of the basin volume.
c. The temporary pool controls runoff from the design storm event.
d. The temporary pool draws down in 2 to .5 days.
e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
f. The basin length to width ratio is greater than 3:1.
a. The basin side slopes above the permanent pool are no steeper than 3:1.
h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
j. A trash rack or similar device is provided for both the overflow and orifice.
k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
I. If the basin is used for sediment and erosion control during construction, clean out of the
A�,-&p basin is specified prior to use as a vet detention basin.
AW10 m. A mechanism is specified which will drain the basin for maintenance or an emergency.
III. WET DETENTION 13ASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
This system (check one) 0 does tr loe not incorporate a vegetated filter at the outlet.
This system (check one) 0 does toes not incorporate pretreatment other than a forebay.
Form SWU-102 Rev 3.99 Page 2 of 4

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Maintenance activities shall be performed as follows:
1. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping,'swales, riprap, etc.).quarterly to maintain
proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed of
in an appropriate manner and shall be handled in a manner that will not adversely impact water quality (i.e.
stockpiling near a wet detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 46 feet in the main pond, the sediment shall be removed.
When the permanent pool depth roads 'i.s feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
(fill in rhe blanks)
Permanent Pool Elevation 149.5'
Sediment Ren oval El. 4 1 75 n
-----H
-`------ Sediment Removal Elevation US 7�%
Bottom Ele anon35 0�0--------------------------------------------- - Bottom Elevation 43.5 2 5%
FOREBAY
MAIN POND
5. Remove cattails and other indigenous wetland plants when the), cover 50% of the basin surface. These
plants shall be encouraged to ¢row along the vegetated shelf and forebay berm.
b. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through
the emergency drain shall be minimized to the maximum extent practical.
Form SWU-102 Rev 3.99 Page 3 of 4

V
7. All components of the wet detention basin system shall be maintained in Qood working order.
I acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Print name: ' 'Nc t &A C.-CrMUOI
Title: 11 tce PregAcnt o f C�c�S{-�a` Cor�Mun 1C.s� +��clG� Piwti t�bn .one
Address: $L J Ci-ea.n -(-s(c $�,,h_ r_ NG_ ZIP-,{(a4
Phone: !�l 0 - Z67
Signature_
Date: S- 22.-bCP
Note: 'the legally- responsible party should not be a homeowners association unless more than 500/a of the lots have been sold and a
resident of the subdivision has been named the president.
Aar4L.` '�a fan_ a Notary Public for the State of �08-41
County of Zh".Swec�-- do hereby certify that :6 �C- -c� &,�t�va�
personally appeared before me this ,Z'XKA day of `hrl4ud aock, , and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements, Witness my hand and official seal,
-� ' 0
`y�
SEAL
My commission expires a069
Form SWU-102 Rev 3.99 Page 4 of 4

4
Permit No.
(to be provided fir 0WQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as an original
DWO Stormwater Management Plan Review:
A complete stormwater management plan submittal inclun des aapplication form, a wet detention basin
supplement for each basin, design calculations, and plans and specifications showing all basin and outlet
structure details. 4
I. PROJECT INFORMATION
Project Name: Leopn,c S Chase coA MolMenance Fai- l-ht
Contact Person: Q:c1 e5 _ac-&Jod Phone Number: ( q10 } 7,61- 1903
For projects with multiple basins, specify which basin this work -sheet applies to:
elevations
Basin Bottom Elevation Z. 5 ft. (floor of the basin)"":
Permanent Pool Elevation 48,5 fit. (elevation of the orifice) `r
Temporary Pool Elevation ( f g fl )
49.5 ft. elevation o the discharge .structure of er ow
areas
Permanent Poo] Surface Arca z3239 sq. ft. (water si.nface areo at the orifice elevation)
Drainage Area 10. (ola4 ac. (on -site and off -site drainage to the basin.)
Impervious Area S. Z6'3 I ac. (on -site and off -site drainage to the basin)
volumes
Permanent Pool Volume ri�7 9Z - cu. ft. (combined volume of maid basin and forebay)
Temporary Pool Volume 2-4,'7(0 cu. ft. (volume detained above the permanent pool)
Forebay Volume 16, It cu. ft. (approximately 20% of total volume)
Other parameters
SAlDA1 Z.((,LfG (sarrface area to drainage area ratio from. DWQ table:)
Diameter of Orifice Zo in. (2 to 5 day ieniporory pool draw -down required)
Design Rainfall in.
Design TSS Removal 2 q0 % (minirrrurn 85% required)
Form SWU-102 Rev 3.99 Page 1 of 4

Footnotes:
l When using the Division SAIDA tables, the correct SA/DA ratio for permanent pool sizing should be computed based upon the
actual impervious % and permanent pool depth. Linear interpolation should be employed to determine the correct value for non-
standard table entries.
2 In the 20 coastal counties, the requirement for a vegetative filter may be waived if the wet detention basin is designed to provide
90% TSS removal. The NCDENR BMP manual provides design tables for both 85% TSS removal and 90% TSS removal.
II. REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
(N.C. Department of Environment, Health and Natural Resources, February 1999) and Administrative Code
Section: 15 A NCAC 2H .1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management 1'ermit
Application Form, the agent may initial below. If a requirement has not been met, attach justification.
Applicants Initials
a. The permanent pool depth is between 3 and 6 feet (required minimum of 3 feet).
b. The forebay volume is approximately equal to 20% of the basin volume.
c. The temporary pool controls runoff from the design storm event.
d. The temporary pool draws down in 2 to 5 days.
e. If required, a 30-foot vegetative filter is provided at the outlet (include non -erosive flow
calculations)
f. The basin length to width ratio is greater than 3:1.
g. The basin side slopes above the permanent pool are no steeper than 3:1.
h. A submerged and vegetated perimeter shelf with a slope of 6:1 or less (show detail).
i. Vegetative cover above the permanent pool elevation is specified.
j. A trash rack or similar device is provided for both the overflow and orifice.
k. A recorded drainage easement is provided for each basin including access to nearest right-
of-way.
1. If the basin is used for sediment and erosion control during construction, clean out of the
Po�i74 basin is specified prior to use as a wet detention basin.
Ak P m. A mechanism is specified which will drain the basin for maintenance or an emergency.
III. WET DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the
vegetated filter if one is provided.
This system (check ogre) 0 does Vdp;4s not incorporate a vegetated filter at the outlet.
This system (check ogre) 0 does does not incorporate pretreatment other than a forebay.
Form SWU-102 Rev 3.99 Page 2 of 4

Maintenance activities shall be performed as follows:
1. After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wet detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re -seed as necessary to maintain good vegetative cover, mow vegetative
cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to maintain
proper functioning.
4. Remove accumulated sediment from the wet detention basin system semi-annually or when depth is
reduced to 75110 of the original design depth (see diagram below). Removed sediment shall be disposed of
in an appropriate manner and shall be handled in a manner that will not adversely impact water quality (i.e.
stockpiling near a wet detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 4..5 feet in the main pond, the sediment shall be removed.
When the permanent pool depth reads 4•5 feet in the forebay, the sediment shall be removed.
Sediment Ren oval El. 4 7
Bottom EA" 2.5_-__� 2
FOREBAY
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 4 S
Sediment Removal Elevation 44 75%
Bottom Elevation 4Z.5 25%
NIAIN POND
5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be encouraged to grow along the vegetated shelf and forebay berm.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through
the emergency drain shall be minimized to the maximum extent practical. Y
Form SWU-102 Rev 199 Page 3 of

7. All components of the wet detention basin system shall be maintained in good working order.
1 acknowledge and agree by my signature below that I am responsible for the performance of the seven
maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Print name: fQ �GCe%Otj&
Title: UiCe Pre,S,Le+ ,t Cco8�C--Omrr,uni ieC @. CUIG- + ?44 C rla(\AAioA . 11kc
Address: 35l 5L) ; mar -Ule 9mck tVC Z-Wq(A
Phone: -nio- ZY7- L1d3,'
Signature:
Date: .S- 1. 2 - Dlv
Note: The legally responsible party should not be a homeowners association unless more than 50% of the lots have been sold and a
resident of the subdivision has been named the president.
I, AOL&-- Ql�SiDr._ a Notary Public for the State of C V-OL110.
County of 1L, �v�� .►etc , do hereby certify that :At9bg-4— "V0.
personally appeared before me this XvuA day of ` ioA1 ,�.J ata�lo , and acknowledge the due
execution of the forgoing wet detention basin maintenance requirements. Witness my hand and official seal,
� Y�o TA
SEAL
My commission expires to - I "�— ':V qQ9
Form SWU-102 Rev 3.99 Page 4 of 4

WET DETENTION POND ANALYSIS
FILE NAME: S:kWQS\POND1060660 Pond 1.WK1
PROJECT#: SW8':013M0:::R 'Kd::l REVIEWER:R _Hail
PROJECT NAME: 0 ep-0 DATE: 08
...................
..........
Receiving Stream:j a W. j�j- Class:
Drainage Basin: dihbic, Index No.
-'�:�� Site Area
' 363Z acres
Drainage Area Fl--�-.- square feet Area in Acres 10.66
IMPERVIOUS AREAS
Buildings
Parking
SW
TOTAL
SURFACE AREA CALCULATION
% IMPERVIOUS
Des. Depth
TSS, 85 or 90:
49.42%
............
VOLUME CALCULATION
Rational ?*
..... ... ..
Des. Storm
Anches
Rv=
0,495
Bottom
1'msl
Perm. Pool
msl
Design Pool
.. .......................
..
MSI
Storage met @elev 49.27 ms]
Req. Volume
19149
1cf
Vol. Prov. at DP
24710
jcf
ORIFICE CALCULATION
Rational C
square feet
square feet
square feet
square feet
square feet
square feet
square feet
square feet
Rational Cc= 0.10
SA/DA Ratio 2.67%
Req. SA 12378 sf
Prov. SA sf
* place a "I" in the box if Rational is used
.
:.......
Perm. Pool Volume= 77322..
Req. Forebay Volume= 15464.4
Provided Volume=
Percent= 23.4%
Elevation
Area Inc. Vol.
Acc. Vol.
A 8.: 5 0 7:
X.-
32 ..',2 X"
0.00
4950
8.100`71' 24710.00
24710.00
Avg. Head =
0.46 ft
Q2 Area
4.90
sq. inches
Flow Q2, cfs
0.111 cfs
Q5 Area =
1.96
sq. inches
Flow Q5, cfs
0.044 cfs
Orifice Area
3.14
sq. inches
No. of Orifices......
...... .. -
Q=
0.071
cfs
Diameter, inches .. weir H x W in x in
.. .........
Drawdown = 3.1 days Surface Area @DP = 26181 sq. ft.
Falling Head Drawdown = 5.4 days
C: 3,300555556 Lz -0.092
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines

WET DETENTION POND ANALYSIS
FILE NAME: S:kWQS\POND1060660 Pond2.WK1
::: PROJECT#: SW H REVIEWERJ
4�
PROJECT NAME: ed-pa �s.. t Chase Clubhouse & Maint DATE: 08-Sep-06
Receiving Stream:
i S a'- W" �": P 1 t 9 W 6M
... ..... .......
Class:
Drainage Basin:
tU...
M ....
.'25
Index No. 1 5 ....................
Site Area
....... .. .. ... .. ......
36­32::'% acres
Drainage Area
2961fs04Q square feet
Area in Acres 6.80
IMPERVIOUS AREAS ..
Rational C
... . ... .
Buildings 0 1`0
.`....-square feet
............................
Parking
square feet
SW . ... xx 0.1...
.......
......... ... ................
square feet
.. ..... .. .. ..
square feet
.......... . ....... .........
. square feet
.............. .............. xxx...
...... . .................
square feet
square feet
TOTAL
1 6147-2-00-1
square feet Rational Cc= 0.16
SURFACE AREA CALCULATION
% IMPERVIOUS
Des. Depth
TSS, 85 or 90:
20.76%
........... .. ..........
............................ ..
........... .. ..........
.................................
SA/DA Ratio 1.23%
Req. SA 3644 sf
Prov. SA -:71 sf
VOLUME CALCULATION * place a "'I" in the box if Rational is used
Rational ?*
. . . . . . . . . .
.............................. . . .. . ... . .
Des. Storm
. ..t=a0
......
inches
Rv=
0.237
Bottom
MSI
Perm. Pool
msi
Design Pool
.. .. .. .. ...... .. ..... ..
..................... ...... .. .. .. .. .. .. .. ..
' 5.0. MSI
Storage met @eleV 49.60 msl
Req. Volume
5844
cf
Vol. Prov. at DP
28849
cf
ORIFICE CALCULATION
FOREBAY
Perm. Pool Volume=
Req. Forebay Volume=
Provided Volume=
Percent=
Elevation
4716&4
23.9%
Inc. Vol. Acc. Vol.
0.00
28849.25 28849.25
Avg. Head =
0.22 ft
Q2 Area =
216 sq. inches
Flow Q2, cfs
0.034 cfs
Q5 Area =
0.87 sq. inches
Flow Q5, cfs
0.014 cfs
Orifice Area
1.77 sq, inches
No. of Orifices
........ ..........
.. ........... ......... .. ...
Q=
0.028 cfs
.. ........... . ...........
........... .......
in x Diameter, inches 50' weir H x W in
......................... .. . .... .. ..... . . . . ......
Drawdown = 2.4 days Surface Area @DP = 58942 sq. ft.
Falling Head Drawdown = 16,0 days
C: 3.284583333 L= -0.044
COMMENTS
Surface Area , Volume and Orifice are within Design Guidelines