20061214 Ver 2_Stormwater Info_20070301

NCDENR-DWQ
Attn: Ms. Cyndi Karoly
2321 Crabtree Blvd.
Parkview Building
Raleigh, NC 27604
Environmental Consultants, PA
;Road Raleigh, North Carolina 27614 Phone: [phone] Fax: [phone]
RE: Stormwater Management Plan for Recreation Tract for Woodcreek (formerly Wild Acres)
Wake County
Dear Ms. Karoly:
On January 31, 2007 we received a 401 Approval - MODIFICATION to impact 0.49 acres of wetland
(0.37 acres permanent impacts, 0.12 acres temporary impacts), 345 linear feet of perennial stream (255
linear feet permanent impacts, 901inear feet temporary impacts), 231 linear feet of intermittent stream (209
linear feet permanent impacts, 22 linear feet temporary impacts) and 43,348 square feet of protected Zone 1
Neuse River basin Riparian buffer and 27,817 square feet of protected Zone 2 Neuse River basin Riparian
buffer.
Per Condition No. 7 of the Modified 401 Approval, we are required to submit a final, written Stormwater
Management Plan for the Recreation Tract prior to any permanent building or other structures occupying
the subject site.
Please fmd enclosed five (5) copies of the Stormwater Management Plan for the Recreation Tract for your
review and approval.
Please call me at if you have any questions.
- - ~,
Sincerely; " ~`
~~ s"
~.. ~ .. ~ n,~-~J~ ~ „ ` .~ n
icole Thoms n
Regulatory Specialist "' ~' ` E ' '` ` " ~ ' a .c ~
Attachments:
5 copies of the Woodcreek Amenity Center Stormwater Management Plan
5 copies of the Extended Detention Wetland Worksheet
5 copies of the signed Operations & Maintenance Agreement
Charlotte Office:
236 LePhillip Court, Suite C
Concord, NC 28025
Phone: [phone]
Fax: [phone]
Greensboro Office:
381.7-E Lawndale Drive
Greensboro, NC 27455
Phone: [phone]
Fax: [phone]
February 28, 2007
S&EC Project # 9615.w1
DWQ Project No. 06-1214, Ver. 2

WETLAND DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
- Woodcreek -Amenity Center Phase -
The wetland detention basin system is defined as the wetland detention basin, pretreatment including forebays
and the vegetated filter if one is provided.
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wetland 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 wetland 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 wetland 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.
If the elevation of the marsh areas exceed the permanent pool elevation, the sediment should be
removed to design levels. This shall be performed by removing the upper 6 inches of soil and stockpiling
it. Then the marsh area shall be excavated six inches below design elevations. Afterwards the stockpiled
soil should be spread over the marsh surface. The soil should not be stockpiled for more than two weeks.
When the permanent pool depth reads 1.50 feet in the micro-pool, the sediment shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 366.0
Sediment Removal EI. 364.5
--------------i-- Sediment Removal Elevation N/A ,~ 75%
----------------------- - ------
Bottom E vation 364.0 5% -------------------- • ,
FOREBAY/micro-pool MAIN 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.
Wetland planting densities in the marsh areas should be maintained by replanting bare areas as needed.
Wetland plants should be encouraged to grow in the marsh areas.
Page 1 of 2

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.
7. All components of the wetland detention basin system shall be maintained in good working order.
8. Level spreaders or other structures that provide diffuse flow shall be maintained every six months. All
accumulated sediment and debris shall be removed from the structure, and a level elevation shall be
maintained across the entire flow spreading structure. Any down gradient erosion must be repaired and/or
replanted as necessary.
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:
Title:_~
Address:_
Phone: C
Signatu~
Date:
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 prgsident.
i
I, ~, LT'~S~ ~.~ ~ ~.~~ t _~ , a Notary Public for the State of U-`~"h - l ~ ,
County of --~~~-~ , do hereby certify th ~ 1 ~ ~-- ~../
personally appeared before me this ~C~ day of ~ , ~, and acknowledge the due
execution of the forgoing wet [wetland] detention basin
official seal,
~q~ n
an n ~ "~+~ - ..
cT
~ n
,~ .
raintenance re uirements. Witness my hand and
SEAL
My commission expires ~ ~ ~- ~l~lJ
Page 2 of 2

DWQ Project No. 06-1214
DIVISION OF WATER QUALITY - 401 EXTENDED DETENTION (and POCKET*) WETLAND WORKSHEET
I. PROJECT INFORMATION (please complete the following information):
Project Name : Woodcreek -Amenity Center Phase (a.k.a. "Recreation Tract" in certification does)
Contact Person: _C. Heath Wadsworth, PE Phone Number: j 919) 238-0323
For projects with multiple basins, specify which basin this worksheet applies to: N/A
Permanent Pool Elevation 366.00 ft. (elevation of the orifice invert out)
Temporary Pool Elevation 367.70 ft. (elevation of the outlet structure invert in)

Permanent Pool Surface Area 11,848 sq. ft. (water surface area at permanent pool elevation)
Drainage Area 10.68 ac. (on-site and off-site drainage to the basin)
Impervious Area 6.02 ac. (on-site and off-site drainage to the basin)
Forebay Surface Area 1.778.5 sq. ft. (at permanent pool elevation approximately 15%)*
Marsh 0"-9" Surface Area 4.148 sq. ft. (at permanent pool elevation approximately 35%)*
Marsh 9"-18" Surface Area 4,143 sq. ft. (at permanent pool elevation approximately 35°~)*
Micro Pool Surface Area 1.778.5 sq. ft. (at permanent pool elevation approximately 15%)*

Temporary Pool Volume 23,087 cu. ft. (volume detained on top of the permanent pool)

SA/DA used 2.28 (surface area to drainage area ratio)*
Diameter of Orifice 2.0 in. (draw down orifice diameter)
REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum; a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project
Applicants Initials
LNa The temporary pool controls runoff from the 1 inch rain.
f_ Nv The basin side slopes are no steeper than 3:1.
Lt/w A planting plan for the marsh areas with plant species and densities is provided.
G~l.,~ Vegetation above the permanent pool elevation is specified.
LJfi,J An emergency drain is provided to drain the basin.
L~r„/ The temporary pool draws down in 2 to 5 days.
Lithe Sediment storage is provided in the permanent pool.
~~ A sediment disposal area is provided.
Ltfw Access is provided for maintenance.
1~ A site speafic, signed and notarized operation and maintenance agreement is provided.
1~~1r,/ The drainage area (including any offsite area) is delineated on a site plan.
~~h./ Access is provided for maintenance.
Lf>h/ Plan details. for the wetland are provided.
-Plan details for the inlet and outlet are provided.
L~G/ A site specific operation and maintenance agreement, signed and notarized by the responsible party is provided (see
http:fm2o.ehnr.state.nc.us/ncwetlands/oandm.doc).
* Pocket Wetlands have different design parameters and are only assumed to remove 35°~ TSS -See pp.19and 20 of the NC DENR
stormwater BMP Manual, April 1999. 10% open water, 50°~ high marsh, 40°~ low marsh.

WITHERS c~ RAVENEL
WOODCREEK -Amenity Center Phase
Stormwater Management Report
Holly Springs, North Carolina
Prepared For:
Preston Development Company
ioo Weston Estates Way
Cary, NC 27513
Prepared By:
WITHERS &RAVENEL, INC
iil MacKenan Drive
Cary, North Carolina 275ii
February, Zoo?
W&R Project No. 02040232.80
,~,:~.,
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'~~' C. Heath Wadsworth, P.E.
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1~

WOODCREEK -Amenity Center Phase
Stormwater Management Report
Holly Springs, North Carolina
INTRODUCTION
The purpose of this study is to document the Stormwater management plan for the Amenity Center
Phase of the proposed development in accordance with the 401 Water Quality Certification and
Authorization Certificate's Additional Conditions (DWQ Project # o6-izi4; designated as "Recreation
Tract" in Additional Condition #7). The plan includes the design of one constructed wetland in the
Amenity Center Phase in order to treat Stormwater runoff. The site is located in the Neuse River Basin
and all ofthe site drainage is received by Middle Creek.
Amenity Center Phase
SITE
}y~ 9L GLIFFCREEK~
'6~a .. ~f
Fgure i. Site
in red on 2005 Aerial Photography; the phase is shown in yellow
The proposed constructed wetland is designed to draw down the first inch of runoff over a z to 5 day
period and is sized according to the Division of Water Quality surface area requirements in order to
achieve 85%Total Suspended Solids and 4o%total nitrogen reduction. The future phases of this
development that require Stormwater management will employ the use of constructed wetlands,
bioretention areas, and/or wet detention basins followed by a forested filter strip in order to meet
Water Quality Certification #34oz in order to manage Stormwater (from 401 Water Quality
Certification the Tract D, Tract F, Tract J, and the Recreation Tract phases require a Stormwater
management plan). These BMPs will be designed and submitted at a later date.
WOODCREEK -Amenity Center Phase i W&R Project ozo4oz3z.8o
Stormwater Management Report February, zoo?

n
L~
WOODCREEK -Amenity Center Phase
• Stormwater Management Report
• Holly Springs, North Carolina
METHODOLOGY
The Stormwater study was conducted using the natural drainage features as depicted by the Wake
• County aerial topographic information (2-ft contours), field surrey data and proposed development
within the drainage areas.
• The scope of work included the following analyses:
Hydrology
• ^ Simulation of the io-year and ioo-year rainfall events for the Holly Springs area
^ Formulation of the io-year, and ioo-year flood hydrographs for the proposed developed
drainage area
Hydraulic
• ^ Routing the 1o-year and ioo-year flood hydrographs for post development runoff through
the proposed Stormwater BMPs
• The results of the hydrologic calculations are used in the hydraulic analyses. The hydraulic design
requires the development of stage-storage and stage-discharge functions for the wet detention
basins. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have been
compiled to create a routing computer simulation model using Haestad Methods PondPack vio.o
• software. This PondPack model was then used to assess the impact of the peak discharges for the
design rainfall events. The PondPack modeling results are provided as appendices to this report.
• HYDROLOGY
The SCS Method was used to develop runoff hydrographs for the zo-year and ioo-year storm events.
• NOAA Atlas i4 rainfall data for Raleigh-Durham International Airport was used to determine the 2!}-
• hour duration rainfall for the io-year and Zoo-year storm events. This method requires three basic
parameters: a curve number (CN), time of concentration (t~, and drainage area.
•
•
Curare numbers were based on soil type and land use. Soil types were delineated from the Soil
Survey of Wake County, North Carolina (November 1970). land use data was determined using aerial
photography and the most recent site plans for the proposed site. The curve numbers used in this
study are listed in the appendix of this report.
Times of concentration were estimated to have a time of concentration of 5 minutes to account for
shallow paved flow, and piping.
HYDRAULICS
Computer simulated reservoir routing ofthe io-year, and Zoo-year design storms utilized stage-
storageand stage-discharge functions. Stage-storage functions were derived from the proposed
contours for the wet detention basins. Anon-linear regression relation for surface area versus
elevation was derived for the BMP. This relation estimates the incremental volume of the basin to
the stage or elevation of the basins. Stage-discharge functions were developed to size the outlet
structures for the wetlands.
CONCLUSIONS
Based on the routing study, the outlet proposed for the constructed wetland passes the Zoo-year
WOODCREEK -Amenity Center Phase
Stormwater Management Report
W&R Project ozogoz3z.8o
February, zoo?

WOODCREEK -Amenity Center Phase
Stormwater Management Report
Holly Springs, North Carolina
storm with at least one foot of freeboard. The results for the run are included in the appendix of this
report. The drainage area map on Sheet 1 of the appendix includes the outlet design for this phase's
BMP. Planting schedules and more detailed design information is included on the Construction
Drawing "Woodcreek - Lockley Drive Extension" submitted with this report.
WOODCREEK -Amenity Center Phase 3 W&R Project ozogo23z.8o
Stormwater Management Report February, zoo?

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ROUTING
CALCULATION S

DA1c (rec site)
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Table of Contents
***t****************** MASTER SUMMARY **:t:t********t********t
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
RDU NOAA 14 Desi Design Storms ...................... 2.01
********************** TC CALCULATIONS *******t******tttt***
DA1C (REC SITE) Tc Calcs ........................... 3.01
*****t**************** CN CALCULATIONS ******************r**
DA1C (REC SITE) Runoff CN-Area ..................... 4.01
****:t****************** POND VOLUMES *t*******xrt*********t*
WETLAND 1C...... Vol: Elev-Area ..................... 5.01
******************** OUTLET STRUCTURES *********************
Outlet lc....... Outlet Input Data .................. 6.01
i
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
2:07 PM
Withers & Ravenel
2/15/2007

Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
2 3.4400
5 4.3000
10 4.9800
25 5.9000
50 6.6300
100 7.3700
1 3.0000
Rainfall
Type
----------------
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA 2yr
RDU NOAA Syr
RDU NOAA 10yr
RDU NOAA 25yr
RDU NOAA SOyr
RDU NOAA 100yr
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(T run= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol Qpeak Qpeak
Node ID Type Event ac-ft
------ Trun
-- hrs
--------- cfs
--------
-----
DA1C ------
(REC ------
SITE) ----
AREA ------
2 ----
1.543 12.1000 33.45
DA1C (REC SITE) AREA 5 2.191 12.1000 43.71
DA1C (REC SITE) AREA 10 2.725 12.1000 51.78
DA1C (REC SITE) AREA 25 3.467 12.1000 60.57
DA1C (REC SITE) AREA 50 4.068 12.1000 65.87
DAlC (REC SITE) AREA 100 4.685 12.1000 71.72
DA1C (REC SITE) AREA 1 1.227 11.9500 22.18
*OUT 10 JCT 2 1.521 R 12.2500 11.83
*OUT 10 JCT 5 2.168 R 12.2000 27.27
*OUT 10 JCT 10 2.701 R 12.1500 37.53
*OUT 10 JCT 25 3.442 R 12.1.500 47.54
*OUT 10 JCT 50 4.043 R 12.1500 52.85
*OUT 10 JCT 100 4.659 R 12.1500 55.83
*OUT 10 JCT 1 1.206 R 12.2500 3.36
Max
Max WSEL Pond Storage
ft ac-ft
-------- ------------
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Master Network Summary Page 1.02
Name.... Watershed
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(T run= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node ID Type Event ac-ft Trun hrs cfs
-------- ft
-------- ac-ft
------------
---------
WETLAND ----
1C ----
IN ----
POND ------
2 ----------
1.543 -- ---------
12.1000 33.45
WETLAND 1C IN POND 5 2.191 12.1000 43.71
WETLAND lC IN POND 10 2.725 12.1000 51.78
WETLAND 1C IN POND 25 3.467 12.1000 60.57
WETLAND 1.C IN POND 50 4.068 12.1000 65.87
WETLAND 1C IN POND 100 4.685 12.1000 71.72
WETLAND 1C IN POND 1 1.227 11.9500 22.18
WETLAND 1C OUT POND 2 1.521 R 12.2500 11.83 368.09 .665
WETLAND 1C OUT POND 5 2.168 R 12.2000 27.27 368.38 .775
WETLAND 1C OUT POND 10 2.701 R 12.1500 37.53 368.55 .837
WETLAND 1C OUT POND 25 3.442 R 12.1500 47.54 368.69 .894
WETLAND 1C OUT POND 50 4.043 R 12.1500 52.85 368.77 .923
WETLAND 1C OUT POND 100 4.659 R 12.1500 55.83 368.84 .953
WETLAND 1C OUT POND 1 1.206 R 12.2500 3.36 367.86 .583
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 2.01.
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
Title... Project Date: 10/18/2006
Project Engineer: CHW
Project Title: Woodcreek
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 19 Desi
Storm Tag Name = 2
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 2yr
2 yr
3.4400 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 5
Data Type, File, ID = Time-Depth Curve RDU NOAA Syr
Storm Frequency = 5 yr
Total Rainfall Depth= 4.3000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 10
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 10yr
10 yr
4.9800 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9909 hrs
Storm Tag Name = 25
Data Type, File, ID = Time-Depth Curve RDU NOAA 25yr
Storm Frequency = 25 yr
Total Rainfall Depth= 5.9000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 50
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 50yr
50 yr
6.6300 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 2.02
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
Title... Project Date: 10/1.8/2006
Project Engineer: CHW
Project Title: Woodcreek
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 100
Data Type, File, ID = Time-Depth Curve RDU NOAA 100yr
Storm Frequency = 100 yr
Total Rainfall Depth= 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs
Storm Tag Name = 1
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Synthetic Storm TypeII 24hr
1 yr
3.0000 in
1
24.0000 hrs
.0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Tc Calcs
Name.... DA1C (REC SITE)
Page 3.01
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: User Defined
Segment #1 Time: .0830 hrs
-------------------------
Total Tc: .0830 hrs
Calculated Tc < Min.Tc:
Use Minimum Tc...
Use Tc = .0833 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Tc Calcs
Name.... DA1C (REC SITE)
Page 3.02
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
___= User Defined =-----------------------------------------------------
Tc = Value entered by user
Where: Tc = Time of concentration
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Runoff CN-Area
Name.... DA1C (REC SITE)
Page 4.01
Fi.le.... K:\04\09-230\09232\H&H\Stormwater\PondPack\woodcreek.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres oC oUC CN
--
--------------------------------
Open space (Lawns parks etc.) - Goo ----
61 ---------
2.980 ----- ----- ----
61.00
Residential Districts - 1/8 acre (t 85 4.810 85.00
Impervious Areas - Paved parking lO 98 2.890 98.00
COMPOSITE AREA & WEIGHTED CN --->
...................................
...................................
.....
..... 1.0.680
..........
..........
............
............ 81.82 (82)
.............
.............
S/N: DOYXYWH3NLBE Withers & Raven el
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Vol: Elev-Area
Name.... WETLAND 1C
Page 5.01
File.... K:\04\09-230\09232\H&H\Stormwater\PondPack\woodcreek.ppw
Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum
(ft) (sq.in) (sq.ft)
--------- (sq.ft)
---------------- (ac-ft)
---------- (ac-ft)
-------------
-----------
366.00 -------------
----- 11853 0 .000 .000
367.00 ----- 13782 38416 .294 .294
368.00 ----- 15770 44295 .339 .633
369.00 ----- 17815 50346 .385 1.018
370.00 ----- 19915 56566 .433 1.451
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (1/3) * (EL2-EL1) * (Areal + Areal + sq.rt.(Areal*Area2))
where: ELI, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for EL1, EL2, respectively
Volume = Incremental volume between EL1 and EL2
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Outlet Input Data
Name.... Outlet lc
Page 6.01
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 366.00 ft
Increment = .10 ft
Max. Elev.= 370.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall El, ft E2, ft
Inlet Box RO ---> CO 367.700 370.000
Orifice-Circular 00 ---> CO 366.000 370.000
Culvert-Circular CO ---> TW 362.000 370.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Outlet Input Data
Name.... Outlet 1c
Page 6.02
File.... K:\04\04-230\04232\H&H\Stormwater\PondPack\woodcreek.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = RO
Structure Type = Inlet Box
--
------
-------------------
# of Openings = ---------
1
Invert Elev. = 367.70 ft
Orifice Area = 16.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 16.00 ft
Weir Coeff. = 3.000
K, Reverse = 1.000
Mannings n = .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 366.00 ft
Diameter = .1700 ft
Orifice Coeff. _ .600
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Type.... Outlet Input. Data
Name.... Outlet 1c
Page 6.03
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
------ = Culvert-Circular
-------------------
-----------
No. Barrels = 1
Barrel Diameter = 2.5000 ft
Upstream Invert = 362.00 ft
Dnstream Invert = 360.00 ft
Horiz. Length = 62.00 ft
Barrel Length = 62.03 ft
Barrel Slope = .03226 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0150
Ke = .5000
Kb = .012271
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) = 1.144
T2 ratio (HW/D) = 1.291
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At T1 Elev = 364.86 ft ---> Flow = 27.16 cfs
At T2 Elev = 365.23 ft ---> Flow = 31.05 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maxi mum Iterations= 40
Min. TW tolerance = .O1 ft
Max. TW tolerance = .Ol ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

Appendix A
Index of Starting Page Numbers for ID Names
A-1
----- D -----
DA1C (REC SITE)... 3.01, 4,01
----- 0 -----
Outlet lc... 6.01
----- R -----
RDU NOAA 14 Desi... 2.01
----- w -----
Watershed... 1.01
WETLAND 1C... 5.01
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 2:07 PM 2/15/2007

BMP SIZING
CALCULATION S

Project Name: Woodcreek -Amenity Center Phase
City/State: Holly Springs, NC
Project #: 2040232
Date: 15-Feb-07
Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85~ Pollutant
Romnval Fffi~ipnrv in the PiPrlmnnt
Impervious
Cover Permanent Pool Dept
3.0 4.0 5.0 6.0 h (feet)
7.0 8.0 9.0
10 0.59 0.49 0.43 0.35 0.31 0.29 0.26
20 0.97 0.79 0.70 0.59 0.51 0.46 0.44
30 1.34 1.08 0.97 0.83 0.70 0.64 0.62
40 1.73 1.43 1.25 1.05 0.90 0.82 0.77
50 2.06 1.73 1.50 1.30 1.09 1.00 0.92
60 2.40 2.03 1.71 1.51 1.29 1.18 1.10
70 2.88 2.40 2.07 1.79 1.54 1.35 1.26
80 3.36 2.78 2.38 2.10 1.86 1.60 1.42
90 3.74 3.10 2.66 2.34 2.11 1.83 1.67
Source: NCDENR/DWQ Stormwater Best Management Practices, pg. S, April 1Nyy
STORMWATER BMP 1 -CONSTRUCTED WETLAND (40% TN Removal)

Land Use Area
(ac) % IA Imp. Area
(ac)
Im ervious 6.02 100 6.0
O en S ace 4.66 0 0.0

Totals 10.68 6.0
Total % Impervious Surface Area = 56.4
Surface Area of Permanent Pool:
Assumed depth = 3 feet
SA/DA ratio = 2.28 % From Table 1.1
Minimum pond surface area (SA) _ (DA * SA/DA ratio)/100
SA = 0.243 acres
10591 sq. ft.
Normal pool elevation = 366.0 feet
Surface area provided = 0.272 acres
11848 sq. ft.
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where, Rv =Runoff coefficient, in./in.
I =Percent impervious
Rv = 0.56 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.496 acre-ft
21606 cu. ft.
Water quality pool elevation= 366.00 feet
Storage volume provided = 0.530 acre-ft
23087 cu. ft.

Project Name: Woodcreek -Amenity Center Phase Project #: 2040232
City/State: Holly Springs, NC Date: 15-Feb-07
STORMWATER BMP 1 -CONSTRUCTED WETLAND (40% TN Removal)
Orifice Calculator

Variables Constants
WQ Volume: 0.496 Acre-ft 21605.76 cf g = 32.2 ft/sz
Head: 1.70 ft 0.85 ft Cd = 0.6
Draw down time: 60 hrs 216000 s
Orifice Area = 0.022533 sq. ft 3.244701 sq. in
Orifice Diameter = 2.032556 in
USE 2 INCH DIAMETER ORIFICE