19970694 Ver 1_Complete File_20080723

IT 0694 s
BASS, NIXON & KENNEDY, INC., CONSULTING ENGINEERS
6310 CHAPEL HILL ROAD, SUITE 250, RALEIGH, NC 27607
919/851-4422 ¦ FAX [phone]
July 23, 2008
N.C. Dept. of Environment and Natural Resources
Division of Water Quality
Attn: Ms. Cyndi Karoly, Supervisor
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 27604
Delivered to Division of Water Quality on July 23, 2008
Received by:
Print Name:
Subject: Colonial Grand at Wakefield Apartments
DWQ Project #970694
Dear Ms. Karoly:
D r ? ?
IEJI. 2 ltl(1
LL'v` YCI1 C ?.d?:A.i?1
WLANDS AND S'fO4tM`A` t L ti{AN
In your letter dated August 27, 2007 (DWQ Project #97-0694v3), you requested that "a
valid approval letter from the appropriate local government indicating that the proposed
activity has an approved SMP and indicating under which state stormwater program the
approval has been granted, and one copy of the approved SMP, including plan details,
calculations and other supporting information" be submitted to your office for your
records. The following information is enclosed in response to your August 27 letter:
• One copy of the August 27, 2007 letter from DWQ to Colonial Realty, LP concerning
the required Stormwater Management Plan (SMP) approval letter from the local
municipality.
• One copy of the City of Raleigh Stormwater Management Plan approval letter for the
Colonial Grand at Wakefield dated July 27, 2008. Please note that the approval
letter indicates that "no disturbance of the Neuse River Buffer will be permitted on
the above referenced projects until the City of Raleigh receives verification of
approval and issuance of buffer permit(s) by NCDWQ." There are no wetland
impacts or Neuse River Buffer impacts proposed for this project.
• One copy of the approved construction drawings pertaining to the Stormwater
Management Plan including the Cover Sheet and sheets C3.1, C3.4, C3.5 and C3.6.
• One copy of the "Design Calculations for Wet Detention `Basin Nos. 1 and 2 for
Water Quality and Pre/Post-Development Stormwater Attenuation".
It is my understanding that submittal of the enclosed information satisfies NCDWQ's
submittal requirements and that construction of the proposed project may proceed
based on the approved Stormwater Management Plan.

Please call me if you have any questions or comments or if you need additional'
information concerning this matter.
Very truly yours,
BASS, NIXON & KENNEDY, INC.
David L. Dunn, PE
CC: David White, Colonial Properties Trust
2
Fwa
n
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Colccn H. Sullins, Director
Division of Water Quality
August 27, 2007
DWQ Project # 97-0694v3
Wake County
CERTIFIED MAIL: RETURN RECEIPT REQUESTED
Colonial Realty, LP
Attn: Mark Barker
2977 Crouse Lane
Burlington, NC 27215
Subject Property: Colonial Grand at Wakefield Apartments
Richland Creek [030402, 27-21, NSW, C]
STORMWATER DUPLICITY NOTICE
Dear Mr. Barker:
y ;' 7
i
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JU 3 HllO
dYa TLAND9 NN11 STOR%#.'Vv 1TcR 3:t! N(., i
This memo is to inform you that the Division of Water Quality (DWQ) has initiated a major change in the
review and approval of Stormwater Management Plans (SMPs) submitted as part of the 401 Certification
application process. This change affects your proposed project, 97-0694v3.
Previously, development activities that require a 401 Certification and also have impervious surface
coverage equal to or greater than 30 percent have been required to submit a SMP for review and approval
by DWQ staff as part of the 401 application process.* Previously, the DWQ review and approval of the
SMP was in addition to any local government review and approval of the SMP that was required under a
state-mandated stormwater program (see list below).
In an effort to maximize the use of limited staff resources at the state and local levels as well as to
streamline the permitting process, a new policy is now in effect. From now on, SMPs that have been
approved by a local government as part of that local government's implementation of a state-
mandated stormwater control program, will not require additional stormwater approval from the
DWQ for the issuance of the 401 Certification.
For the purpose of this policy, local approval of the SMP under the following state stormwater programs
shall satisfy the stormwater requirement for receiving a 401 Certification:
- Water Supply Watershed II, III, and IV
- Local Implementation of the NPDES Phase 2 Program
- Universal Stormwater Management Program
- Nutrient Sensitive Waters (NSW) Stormwater Program
- Randleman Lake Water Supply Watershed Stormwater Program.
* Note: Under the renewal of the NC General Certifications, it has been proposed to lower the impervious surface
threshold to 24% when the new General Certifications are expected to go into effect on October 15, 2007.
Dix 401 OversightiLxpress Review Permitting Unit N hCaro
r'?aturnina
ly
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone]! FAX [phone] Internet: blip:' h2o rn.statc.n? u. ncnctl?n<ls
An Fqual Opportunity!Attirmative Action Employer - 50% Recycled! 10% Post Consumer Paper
Mr. MarK barkcr
Page 2 of 2
August 27, 2007
From now on, 401 Applications for proposed activities that exceed the impervious surface threshold
and are within a local jurisdiction that is implementing a state stormwater program must either submit
Item I or Item 2 below.
1. A valid approval letter from the appropriate local government indicating that the proposed
activity has an approved SMP and indicating under which state stormwater program the approval
has been granted, and one copy of the approved SMP, including plan details, calculations and
other supporting information. OR
If the necessary local approval of the SMP has not yet been obtained at the time of 401
Application, the application should indicate that a SMP has been, or will be, submitted for local
government approval. The applicant should indicate the local government that approval is being
requested from, and indicate under which state stormwater program the activity will be covered.
Any 401 Certification approved under this scenario shall be conditioned so that the proposed
impacts shall not commence until such time that the appropriate local approval has been granted.
401 Applications for proposed activities that exceed the impervious surface threshold but are not within a
local j urisdiction that is implementing a state stormwater program must include a complete SMP for
DWQ review and approval.
Notwithstanding this new policy, the Director of the DWQ reserves the right to review individual
stormwater management plans on a case-by-case basis in order to ensure that a proposed activity will not
violate water quality standards. Additionally, the DWQ Director reserves the prerogative to provide
continents to local governments of special provisions that may need to be incorporated into locally-
reviewed SMPs in order to provide an enhanced level of protection to sensitive watersheds or to provide
an enhanced level of stormwater control on unusual projects.
This new policy does not affect the DWQ's authority and responsibility to review 401 Applications for
avoidance and minimization of all impacts to surface waters and wetlands. In addition, the DWQ will
retain the authority and responsibility to review projects for impacts to protected riparian buffers in areas
where buffer protection has not been locally delegated.
Please direct questions regarding this new policy to Ian McMillan at 919-7154631
ian.mcntillan iuncmail.net or Annette Lucas at 919-715-3425 or annette.lucasicricu
Cyndi Karoly, Sup rvisor
401 Oversight/Express Review Permitting Unit
CBKlrnj
cc: Lauren Cobb, DWQ Raleigh Regional Office
USACE Raleigh Regulatory Field Office
File Copy
Central Files
rilename: 97-0694v3ColonialGrandatWakefieldApartments(Wake)_S W_Duplicity_Notice
OF R,,
bS
?N CA1?
City of Raleigh Public Works
Stormwater Engineers
Date: July 7, 2008
To: North Carolina Division of Water Quality/401 Section
512 N. Salisbury St.
Raleigh NC, 27604
[phone]
1617 Mail Service Center
Raleigh, NC 27699
Re: Stormwater Management Plan approval by City of Raleigh
To Whom It May Concern:
The stormwater management plan (SMP) for Colonial Grand at Wakefield (GH-3-07)
(Transaction # 197942) has been reviewed and approved by the City of Raleigh for compliance
with our stormwater requirements. This approval is for the purpose and design that you show in
the above referenced plans. If the SMP changes this approval is voided and the applicant will be
required to request a new approval letter.
No disturbance of the Neuse River Buffer will be permitted on the above referenced projects until
the City of Raleigh receives verification of approval and issuance of buffer permit(s) by
NCDWQ.
Should you have any questions, please contact me at [phone].
Lisa S. Booze, CFM
City of Raleigh
Public Works/Stormwater Management
POB 590
Raleigh, NC 27602-0590
email: [e-mail]
phone: [phone]
FAX: [phone]
219 Fayetteville St. PO Box 590, Raleigh, NC 27602
Voice [phone] fax[phone]

1

BASS, NIXON & KENNEDY, INC., CONSULTING ENGINEERS
6310 CHAPEL HILL ROAD, SUITE 250, RALEIGH, NC 27607
919/851-4422 ¦ FAX [phone]
COLONIAL GRAND AT WAKEFIELD
APARTMENTS
RALEIGH, NORTH CAROLINA
DESIGN CALCULATIONS
FOR WET DETENTION BASIN
NOS. 1 AND 2
FOR WATER QUALITY AND
PRE/POST-DEVELOPMENT
STORMWATER ATTENUATION

PREPARED BY
BASS, NIXON AND KENNEDY, INC.
JULY 14, 2007
t
7

i1IS1d7

BASS, NIXON & KENNEDY, INC., CONSULTING ENGINEERS
6310 CHAPEL HILL ROAD, SUITE 250, RALEIGH, NC 27607
919/851-4422 ¦ FAX [phone]
COLONIAL GRAND AT WAKEFIELD
APARTMENTS
RALEIGH, NORTH CAROLINA
WET DETENTION BASINS
' DESIGN CALCULATIONS
July 14, 2007
k

The following calculations are for the design of the wet detention basins for the Colonial
Grand at Wakefield Apartments in Raleigh, North Carolina. The wet detention basins
are designed as stormwater BMP's for nitrogen reduction as well as to provide
stormwater attenuation for the 2-year and 10-year, 24-hour storms. The Stormwater
Best Management Practices dated April, 1999 by NCDENR (Section 1.0 - Wet
Detention Basins) and the City of Raleigh Stormwater Management Design Manual
dated January, 2002 were used for design of the wet detention basins. The stormwater
basins are designed to provide 85% TSS removal as required by the 401 approval from
the N.C. Division of Water Quality (DWQ).
There are two wet detention basins proposed for the site: wet detention basin No. 1 is
located on the south side of the site and wet detention basin No. 2 is located on the
north side of the site. The area draining to wet detention basin No. 1 is less than 10.0
acres; consequently, basin No. 1 provides for a 10% TN removal rate (same as for a dry
detention basin). The area draining to wet detention basin No. 2 is greater than 10.0
acres; consequently, basin No. 2 provides for a 25% TN removal rate per the City of
Raleigh Stormwater Design Manual. The following summarizes design information for
the two basins:
Wet Detention Basin No. 1
The following summarizes the design calculations for wet
provide stormwater treatment for Nitrogen reduction as well
so that the site Q2 and Q10 post-development discharge
development discharge:
' • Determine Surface Area Required for Permanent Pool
Drainage Area = 6.9 acres
' Impervious Area = 4.3 acres
Percent Impervious = 62.3%
Set Permanent Pool Level at 267.50 Feet
,
' Colonial Grand - Stormwater Calcs.
detention basin No. 1 to
as stormwater attenuation
does not exceed the pre-
7114/2007
See Appendix A for the water quality pond design information using
excel spreadsheet.
Summary of Design for Wet Detention Basin No. 1
The wet detention basin will need to provide stormwater attenuation so that the
post-development runoff for the 2-year and 10-year, 24-hour storms does not
exceed the pre-development runoff. Set the top of the riser above the temporary
pool elevation to provide additional storage for stormwater detention:
Top of Basin Embankment = 271.00 Ft.
Set Top of Emergency Spillway = 269.60 Ft.
Set Top of Riser = 269.20 Ft.
Set Temporary Pool = 268.32 Ft. +/-
Set Invert of 2" Dia. Drawdown
Pipe (Perm. Pool) = 267.50 Ft.
Set Basin Invert = 262.00 Ft.
• Calculate the Q2/Q10 Pre- and Post-Developed Discharge
The following summarizes the pre- and post-developed Q2 and Q10 discharge for
the area draining to water quality basin No. 1:
Drainage Area = 6.9 Acres
Pre-Dev. Composite C = 0.20
Post-Dev. Composite C = 0.70
Intensity (2-year) = 5.76 In/Hr
Intensity (10-year) = 7.22 In/Hr
Intensity (100-year) = 9.72 In/Hr
Use the Rational Equation to calculate the Q2, Q10 and Q100 pre- and post-
developed discharge for the area draining to water quality basin No. 1:
Pre-Developed Discharge
Q2 = 7.9 cfs
Q10 = 10.0 cfs
Q100 = 13.4 cfs
Post-Developed Discharge
Q2 = 27.8 cfs
Q10 = 34.9 cfs
Q100 = 46.9 cfs
Minimum Attenuation Required
Q2 = 19.9 cfs
Q10 = 24.9 cfs
Colonial Grand - Stormwater Calcs. 2 7/14/2007

• Summary of Stormwater Routing Calculations:
Q2 Discharge into Basin
Q2 Discharge out of Basin
27.8 CFS
4.5 CFS < 7.9 CFS Okay
Q10 Discharge into Basin
Q10 Discharge out of Basin
Q2 Waterlevel
Q10 Waterlevel
Q100 Waterlevel
34.9 CFS
= 8.4 CFS < 10.0 CFS Okay
269.41 Feet
269.56 Feet
= 269.79 Feet
See Appendix B for Wet Detention Basin No. 1 routing calculations
using PondPack computer software by Haestad Methods.
Wet Detention Basin No. 2
The following summarizes the design calculations for wet detention basin No. 2 to
provide stormwater treatment for Nitrogen reduction as well as stormwater attenuation
so that the site Q2 and Q10 post-development discharge does not exceed the pre-
development discharge:
' Determine Surface Area Required for Permanent Pool
Drainage Area = 11.3 acres
' Impervious Area = 6.9 acres
Percent Impervious = 61.1%
Set Permanent Pool Level at 275.00 Feet,
See Appendix C for the water quality pond design information using
excel spreadsheet.
' Summary of Design for Water Quality Basin No. 2
' The wet detention basin will need to provide stormwater attenuation so that the
post-development runoff for the 2-year and 10-year, 24-hour storms does not
exceed the pre-development runoff. Set the top of the riser above the temporary
' pool elevation to provide additional storage for stormwater detention:
' Top of Basin Embankment _ 282.00 Ft.
Set Top of Riser 279.50 Ft.
Set Temporary Pool = 276.44 Ft. +/-
Colonial Grand - Stormwater Calcs. 3 7/14/2007
Set Invert of 2.5" Dia. Drawdown
Pipe (Perm. Pool) = 275.00 Ft.
Set Basin Invert = 269.50 Ft.
• Calculate the Q2/Q10 Pre- and Post-Developed Discharge
The following summarizes the pre- and post-developed Q2 and Q10 discharge for
the area draining to water quality basin No. 2:
Drainage Area = 11.3 Acres
Pre-Dev. Composite C = 0.20
Post-Dev. Composite C = 0.70
Intensity (2-year) = 5.76 In/Hr
Intensity (10-year) = 7.22 In/Hr
Intensity (100-year) = 9.72 In/Hr
Use the Rational Equation to calculate the Q2 and Q10 pre- and post-developed
discharge for the area draining to water quality basin No. 2:
Pre-Developed Discharge
Q2 = 13.0 cfs
Q10 = 16.3 cfs
Q100 = 22.0 cfs
Post-Developed Discharge
Q2 = 45.6 cfs
Q10 = 57.1 cfs
Q100 = 76.9 cfs
Minimum Attenuation Required
Q2 = 32.6 cfs
Q10 = 40.8 cfs
• Summary of Stormwater Routing Calculations:
Q2 Discharge into Basin = 45.6 CFS
Q2 Discharge out of Basin = 0.7 CFS < 13.0 CFS Okay
Q10 Discharge into Basin
Q10 Discharge out of Basin
Q2 Waterlevel
Q10 Waterlevel
Q100 Waterlevel
Top of Dam
Colonial Grand - Stormwater Calcs. 4
57.1 CFS
2.3 CFS < 16.3 CFS Okay '
279.51 Feet
279.57 Feet '
= 279.80 Feet
282.00 Feet
7/14/2007 '

See Appendix D for Wet Detention Basin No. 2 routing calculations
using PondPack computer software by Haestad Methods.
' Summary of Overall Site Q2/Q10 Pre- and Post-Developed Discharge
• Calculate the Q2 and Q10 pre- and post-developed discharge for the overall site.
The following summarizes the pre- and post-developed Q2 and Q10 discharge for
the overall site:
' Overall Site Area = 26.5 Acres
Pre-Dev. Composite C = 0.20
Post-Dev. Composite C = 0.60 (for overall site)
Intensity (2-year) = 5.76 In/Hr
Intensity (10-year) = 7.22 In/Hr
Use the Rational Equation to calculate the Q2 and Q10 pre- and post-developed
' discharge for the overall site:
Pre-Developed Discharge
t Q2 = 30.5 cfs
Q10 = 38.3 cfs
' Post-Developed Discharge without Stormwater Attenuation
Q2 91.6 cfs
Q10 = 114.8 cfs
' Attenuation Required
Q2 = 61.1 cfs
' Q10 = 76.5 cfs
• Summarize the Q2 and Q10 attenuation provided by Water Quality Basin Nos. 1 and
2 from the above information and attached routing calculations:
' Water Quality Basin No. 1
Q2 Inflow = 27.8 cfs
' Q2 Outflow = 4.5 cfs
Attenuation Provided for 2-Year Storm = 23.3 cfs
Q10 Inflow = 34.9 cfs
Q10 Outflow = 8.4 cfs
Attenuation Provided for 10-Year Storm = 26.5 cfs
Water Quality Basin No. 2
Q2 Inflow = 45.6 cfs
Colonial Grand - Stormwater Calcs. 5 7/14/2007
Q2 Outflow = 0.7 cfs
Attenuation Provided for 2-Year Storm = 44.9 cfs
Q10 Inflow = 57.1 cfs
Q10 Outflow = 2.3 cfs
Attenuation Provided for 10-Year Storm = 54.8 cfs
Total Q2 Attenuation Provided =
Minimum Q2 Attenuation Req'd =
Total Q10 Attenuation Provided =
Minimum Q10 Attenuation Req'd =
23.3 cfs + 44.9 cfs
68.2 cfs
61.1 cfs < 68.2 cfs Okay
26.6 cfs + 54.8 cfs
81.4 cfs
76.5 cfs < 81.4 cfs Okay
Colonial Grand - Stormwater Calcs. 6 7/14/2007
1
0

APPENDIX A -

u

n
SUMMARY OF WATER
QUALITY BASIN DESIGN
CALCULATIONS FOR WET
DETENTION BASIN NO. 1
USING EXCEL SPREADSHEET
Colonial Grand - Stormwater Calcs. 7 7/14/2007
Water Quality Retention Calculations
Project Name: Colonial Grand at Wakefield - Wet Detention Basin No. 1
' Date: July 14, 2007
Determine Surface Area Required for Permanent Pool:
' Drainage Area (ac): 6.9
Impervious Area (ac): 4.3
Percent Impervious: 62.3%
Perm. Pool Depth (ft): 3
SA/DA @ 60% 2.4 (from Table 1.1 of NCDENR's Stormwater BMP manual)
SA/DA @ 70% 2.88 (from Table 1.1 of NCDENR's Stormwater BMP manual)
' Interpolated SA/DA: 2.51
Req. Surface Area (so: 7,548 (at permanent pool elevation)
' Perm. Pool Elevation: 267.50
Provided Surface Area (so: 17,492 OK - Surface area requirement met
Provided Storage (cf): 53,953
Check Hydraulic Depth (ft): 3.08 OK - Hydraulic depth requirement met
Calculate the Volume Required to Treat the First Flush:
Rainfall to Treat: 1 inch(es)
' Runoff Coefficient (Rv) = 0.05 + 0.009`(% Impervious)
Runoff Coefficient (Rv): 0.61 in/in
Runoff Volume (V) = Rainfall ` (Rv) " (Drainage Area)
Runoff Volume (V): 15,300 CF
Calculate the Depth Required for the Temporary Pool:
Perm. Pool Elevation: 267.50
Provided Surface Area (so: 17,492 (at permanent pool elevation)
Provided Storage (cf): 53,953
Volume Req. for Temp. Pool (CF): 15,300 (this amount required above Perm. Pool)
Total Volume Req Temp & Perm(CF): 69,253
El. Of Temp. Pool Between: 268.00 and 269.00
El. Of Temp. Pool: 268.32
Depth of Temp. Pool (ft): 0.82 measured from perm. Pool elevation
Determine the Orifice Size for 2-5 Day Drawdown:
Orifice Invert Elevation: 267.50
Elevation of Temp. Pool: 268.32
Orifice Diameter (in): 2.00
Use the orifice equation to determine flow and drawdown time:
Orifice Equation: Q = C * A i (2gh)^0.5
Volume to Draw Down (CF): 15,300
Flow for 2-Day Drawdown (CFS): 0.089
Flow for 5-Day Drawdown (CFS): 0.035
0.6
g
g (SF/s):
32.2
h (ft): 0.368 (average driving head to centerline of orifice)
A (so: 0.0218
Solve Orifice Equation for Q (CFS): 0.064
Drawdown Time (Days): 2.78 OK - Drawdown between 2 and 5 days.
1
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APPENDIX B -
SUMMARY OF ROUTING
CALCULATIONS FOR WET
' DETENTION BASIN NO. 7
FOR THE Q2, Q10 AND Q100
STORMS USING PONDPACK
' COMPUTER SOFTWARE BY
HAESTAD METHODS
1
Colonial Grand - Stormwater Calcs. 8 7/14/2007

Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
--------------------------
--------------------------
JOB TITLE
--------------------------
--------------------------

1
1

0

1
1
COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q2 ROUTING CALCULATIONS
The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
t PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Table of Contents
Table of Contents
i
********************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A...... 2-Year
SCS Unit Hyd. Summary .............. 3.01
**************s******** POND VOLUMES **::*******************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.05
********:***:****s***** POND ROUTING ***********************
POND 1 OUT 2-Year
Pond Routing Summary ............... 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007

Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event in Type RNF File RNF ID
------------
2-Year ------ ---------------- --------
3.6000 Synthetic Curve SCSTYPES ----------------
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= 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
-------- -------- ---------
BASIN D.A. AREA 2 1.571 11.9000 27.81
*DISCHARGE PT 1 JCT 2 1.425 12.1500 4.48
POND 1 IN POND 2 1.571 11.9000 27.81
POND 1 OUT POND 2 1.425 12.1500 4.48 269.41
2.104
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q2 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Storm Tag Name = 2-Year
Page 2.01
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 2 yr
Total Rainfall Depth= 3.6000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 62180250GA84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
' Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 2-Year Event: 2 yr
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 2-Year
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 2 year storm
Duration = 24.0000 hrs Rain Depth = 3.6000 in
' Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
' HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
CALCS\
HYG File - ID - BASIN D.A. 2-Year
Tc (Min. Tc) = .0833 hrs
' Drainage Area = 6.900 acres Runoff CN= 92
--------------------------------------------
--------------------------------------------
Computational Time Increment = 01111 hrs
' Computed Peak Time 11.9175 hrs
Computed Peak Flow 28.56 cfs
' Time Increment for HYG File .0500 hrs
Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output 27.81 cfs
--------------------------------------------
--------------------------------------------
DRAINAGE AREA

ID:None Selected
CN = 92
Area = 6.900 acres
S = .8696 in
0.2S = .1739 in
Cumulative Runoff
-------------------
2.7325 in
1.571 ac-ft
HYG Volume... 1.571 ac-ft (area under HYG curve)
***** UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: None Selected)
'
Computational Incr, Tm = .01111 hrs = 0. 20000 Tp
Unit Hyd. Shape Fact or = 483.432 (37.46% under rising limb)
K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
'
Receding/Rising, Tr/ Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 93.85 cfs
'
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Vol: Elev-Area
Name.... POND 1
Page 4.01
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 1
Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum
(ft) (sq.in) (acres)
----------
- (acres)
---------------- (ac-ft)
---------- (ac-ft)
-------------
-----------
262.00 ----------
-
----- .1180 .0000 .000 .000
264.00 ----- .1788 .4421 .295 .295
266.00 ----- .2577 .6512 .434 .729
268.00 ----- .4498 1.0480 .699 1.427
270.00 ----- .5379 1.4796 .986 2.414
271.00 ----- .5968 1.7013 .567 2.981
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: EL1, 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: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
1
1
1
Type.... Outlet Input Data Page 5.01
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 262.00 ft
Increment = .50 ft
Max. Elev.= 271.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
----------------- ---- ------- --------- ---------
Stand Pipe SP ---> CV 269.200 271.000
Orifice-Circular OR ---> CV 267.500 271.000
Culvert-Circular CV ---> TW 261.500 271.000
Weir-Rectangular WR ---> TW 269.600 271.000
TW SETUP, DS Channel

S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 ,
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS I
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID = SP
Structure Type = Stand Pipe
-----------------
# of Openings -------------
= 1 ------
Invert Elev. = 269.20 ft
Diameter = 4.0000 ft
Orifice Area = 12.5664 sq.ft
Orifice Coeff. _ .600
Weir Length = 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 267.50 ft
Diameter = .1700 ft
Orifice Coeff. _ .600
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
' Type.... Outlet Input Data Page 5.03
Name.... OUTLET
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
' OUTLET STRUCTURE INPUT DATA
' Structure ID = CV
Structure Type = Culvert-Circular
------------------------------------
No. Barrels 1
Barrel Diameter 1.5000 ft
Upstream Invert 261.50 ft
Dnstream Invert = 260.50 ft
' Horiz. Length 100.00 ft
Barrel Length 100.01 ft
Barrel Slope = .01000 ft/ft
' OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entrance loss)
' Kb .018213 (per ft of full flow)
Kr .5000 (reverse entrance loss)
HW Convergence = .001 +/- 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) = 1.155
' T2 ratio (HW/D) 1.302
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 = 263.23 ft --> Flow = 7.58 cfs
At T2 Elev = 263.45 ft --> Flow = 8.66 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Outlet Input Data Page 5.04 '
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA '
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
269.60 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Composite Rating Curve
Name.... OUTLET
Page 5.05
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETEN TION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW
' ***** COM POSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
---------------- -
Elev. Q -----
TW El -- Converge
ev Error -------------------------
ft cfs ft +/-ft Contributing Structures
--------
262.00 ------- -
.00 -----
Free -- -----
Outfall --------------------------
(no Q: SP,OR,CV,WR)
262.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
263.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
' 263.50
264.00 .00
.00 Free
Free Outfall
Outfall (no Q: SP,OR,CV,WR)
(no Q: SP,OR,CV,WR)
264.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
265.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
265.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
' 266.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
266.50 .00 Free Outfall (no Q: SP,OR,CV,WR)

' 267.00
267.50 .00
.00 Free
Free Outfall
Outfall (no Q: SP,OR,CV,WR)
(no Q: SP,OR,CV,WR)
268.00 .07 Free Outfall OR,CV (no Q: SP,WR)
268.50 .10 Free Outfall OR,CV (no Q: SP,WR)
269.00
269.20 .13
.14 Free
Free Outfall
Outfall OR,CV (no Q: SP,WR)
OR,CV (no Q: SP,WR)
269.50 6.34 Free Outfall SP,OR,CV (no Q: WR)
269.60 9.69 Free Outfall SP,OR,CV (no Q: WR)
270.00 44.78 Free Outfall SP,CV,WR (no Q: OR)
' 270.50 99.53 Free Outfall SP,CV,WR (no Q: OR)
271.00 172.43 Free Outfall SP,CV,WR (no Q: OR)

S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01 '
Name.... POND 1 OUT Tag: 2-Year Event: 2 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q2 ANALYSIS - 7-14-07).PPW I
Storm... TypeII 24hr Tag: 2-Year
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - POND 1 IN 2-Year
Outflow HYG file = NONE STORED - POND 1 OUT 2-Year
Pond Node Data = POND 1
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 267.50 ft
Starting Volume = 1.216 ac-fit
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 27.81 cfs at 11.9000 hrs
Peak Outflow = 4.48
- cfs at 12.1500 hrs
-----------------------
----
Peak ---------------
Elevation = ----------
269.41 ft
Peak Storage = 2.104 ac-ft
MASS BALANCE (ac-ft)
-----
-------------
+ Initial Vol --------
= 1.216
+ HYG Vol IN = 1.571
- Infiltration = .000
- HYG Vol OUT = 1.425
- Retained Vol = 1.360
Unrouted Vol = -.003 ac-ft
(.180% of Inflow Volume)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007
Appendix A A-1
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 2-Year... 3.01
----- 0 -----
OUTLET... 5.01, 5.05
----- P -----
POND 1... 4.01, 6.01
----- R -----
Raleigh... 2.01
----- W -----
Watershed... 1.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:20:04 Date: 07/14/2007

0

1
1
1
1

n
1
Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
JOB TITLE
--------------------------
--------------------------
COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q10 ROUTING CALCULATIONS
The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Table of Contents
Table of Contents
i
********************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A...... 10-Yea
SCS Unit Hyd. Summary .............. 3.01
***s***:*************** POND VOLUMES ***********************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.05
******s**************:* POND ROUTING *****s*****************
POND 1 OUT 10-Yea
Pond Routing Summary ............... 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event in Type RNF File RNF ID
-------------
------------
10-Yea ------
5.3800 ------------
Synthetic Cu ---- --------
rve SCSTYPES ---
TypeII 24hr
MAS TER NETWORK SUMMARY
SCS U nit Hydrogra ph Method
(*Node=Ou tfall; +Node =Diversion;)
(Trun= 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
-------- -------- ---------
BASIN D.A. AREA 10 1.928 11.9000 34.86
*DISCH ARGE PT 1 JCT 10 1.789 12.1000 8.41
POND 1 IN POND 10 1.928 11.9000 34.86
POND 1 OUT POND 10 1.789 12.1000 8.41 269.56
2.182
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q10 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Storm Tag Name = 10-Yea
Page 2.01
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 10 yr
Total Rainfall Depth= 5.3800 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
' Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 10-Yea Event: 10 yr
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 10 Yea
t SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 24.0000 hrs Rain Depth = 5.3800 in
Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
HYG Dir = R?\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
CALCS\
HYG File - ID BASIN D.A. 10-Yea
Tc (Min. Tc) = .0833 hrs
Drainage Area = 6.900 acres Runoff CN= 81
--------------------------------------------
--------------------------------------------
Computational Time Increment = .01111 hrs
' Computed Peak Time 11.9175 hrs
Computed Peak Flow 36.11 cfs
' Time Increment for HYG File .0500 hrs
Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output 34.86 cfs
--------------------------------------------
--------------------------------------------
DRAINAGE AREA
1
ID:None Selected
CN = 81
Area = 6.900 acres
S = 2.3001 in
0.2S = .4600 in
Cumulative Runoff
-------------------
3.3526 in
1.928 ac-ft
HYG Volume... 1.928 ac-ft (area under HYG curve)
***** UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: None Selected)
'
Compu tational Incr, Tm = .01111 hrs = 0. 20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
'
Reced ing/Rising, Tr/Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 93.85 cfs
' Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total
1 unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Vol: Elev-Area Page 4.01
Name.... POND 1
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 1
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft) (sq.in) (acres)
------- (acres)
---------------- (ac-ft)
---------- (ac-ft)
-------------
-----------
262.00 ---------------
----- .1180 .0000 .000 .000
264.00 ----- .1788 .4421 .295 .295
266.00 ----- .2577 .6512 .434 .729
268.00 ----- .4498 1.0480 .699 1.427
270.00 ----- .5379 1.4796 .986 2.414
271.00 ----- .5968 1.7013 .567 2.981
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: EL1, 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: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Outlet Input Data Page 5.01
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 262.00 ft
Increment = .50 ft
Max. Elev.= 271.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to UpStream)
< --- > Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
----------------- ---- ------- --------- ---------
Stand Pipe SP ---> CV 269.200 271.000
Orifice-Circular OR ---> CV 267.500 271.000
Culvert-Circular CV ---> TW 261.500 271.000
Weir-Rectangular WR ---> TW 269.600 271.000
TW SETUP, DS Channel
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 i
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS I
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID = SP
Structure Type
----------------- = Stand Pipe
-------------
------
# of Openings = 1
Invert Elev. = 269.20 ft
Diameter = 4.0000 ft
Orifice Area = 12.5664 sq.ft
Orifice Coeff. _ .600
Weir Length = 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000.
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 267.50 ft
Diameter = .1700 ft
Orifice Coeff. _ .600
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
' Type .... Outlet Input Data Page 5.03
Name .... OUTLET
' File .... R:\2006JOB5\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET D ETENTION BASIN 1 (Q10 ANALYSIS - 7-14-0 7).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID = CV
' Structure Type = Culvert-C ircular
------
' -----------------------------
No. Barrels 1
Barrel Diameter 1.5000 -
ft
Upstream Invert 261.50 ft
Dnstream Invert = 260.50 ft
' Horiz. Length 100.00
Barrel Length 100.01 ft
ft
Barrel Slope = .01000 ft/ft
' OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entran ce loss)
' Kb .018213
Kr .5000 (per ft of full
(reverse entran flow)
ce loss)
HW Convergence .001 +/- 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) = 1.155
' T2 ratio (HW/D) 1.302
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,

' int
At erpolate between flows at T1 & T2...
T1 Elev = 263.23 ft --- > Flow =
7.58 cfs
At T2 Elev = 263.45 ft --> Flow = 8.66 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Outlet Input Data Page 5.04 '
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA ,
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
269.60 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
' Type.... Composite Rating Curve
Name.... OUTLET
Page 5.05
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ----- --- Converge -------- -----------------
'
Elev. Q TW Elev Error
ft cfs ft +/-ft Contribu ting Structures
--------
262.00 -------
.00 -----
Free --- -----
Outfall ---------
(no Q: -----------------
SP,OR,CV,WR)
262.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
263.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
263.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
'
264.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
264.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
265.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
265.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
'
266.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
266.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
267.00 .00 Free Outfall (no Q: SP,OR,CV,WR)
'
267.50 .00 Free Outfall (no Q: SP,OR,CV,WR)
268.00 .07 Free Outfall OR,CV ( no Q: SP,WR)
268.50 .10 Free Outfall OR,CV ( no Q: SP,WR)
269.00 .13 Free Outfall OR,CV ( no Q: SP,WR)
'
269.20 .14 Free Outfall OR,CV ( no Q: SP,WR)
269.50 6.34 Free Outfall SP,OR,CV (no Q: WR)
269.60 9.69 Free Outfall SP,OR,CV (no Q: WR)
270.00 44.78 Free Outfall SP,CV,WR (no Q: OR)
'
270.50 99.53 Free Outfall SP,CV,WR (no Q: OR)
271.00 172.43 Free Outfall SP,CV,WR (no Q: OR)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01 '
Name.... POND 1 OUT Tag: 10-Yea Event: 10 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q10 ANALYSIS - 7-14-07).PPW I
Storm... TypeII 24hr Tag: 10-Yea
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - POND 1 IN 10-Yea
Outflow HYG file = NONE STORED - POND 1 OUT 10-Yea
Pond Node Data = POND 1
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 267.50 ft
Starting Volume = 1.216 ac-ft
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 34.86 cfs at 11.9000 hrs
Peak Outflow = 8.41 cfs at 12.1000 hrs
------
-----
Peak --------------
Elevation = ----------
269.56 ------------------
ft
Peak
-----
----- Storage =
--------------
-------------- 2.182
----------
---------- ac-ft
------------------------
------------------------
MASS BALANCE (ac-ft)
--------------------
+ Initial Vol = ------
1.216
+ HYG Vol IN = 1.928
- Infiltration = .000
- HYG Vol OUT = 1.789
- Retained Vol = 1.351
Unrouted Vol = -.003 ac-ft
(.156% of Inflow Volume)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007
1
1
1
1
1
1
1
Appendix A
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 10-Yea... 3.01
---- 0 -----
OUTLET... 5.01, 5.05
----- P -----
POND 1... 4.01, 6.01
----- R -----
Raleigh... 2.01
----- W -----
Watershed... 1.01
A-1
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:15:51 Date: 07/14/2007

Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
JOB TITLE
--------------------------
--------------------------
COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q100 ROUTING CALCULATIONS
The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Table of Contents
Table of Contents
i
********************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A...... 100-Ye
SCS Unit Hyd. Summary .............. 3.01
********s************** POND VOLUMES ***********************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.05
**************s******** POND ROUTING *********s*************
POND 1 OUT 100-Ye
Pond Routing Summary ............... 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event in Type RNF File RNF ID
----
------------ ------ ----------------
100-Ye 8.0000 Synthetic Curve SCSTYPES TypeII 24hr
1
1
1
1
1
1
1
1
1
1
1
1

MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol
Storage
Node ID
--------------
Type
--- ----
Event
------
ac-ft Trun
--------
BASIN D.A. AREA 100 2.593
*DISCHARGE PT 1 JCT 100 2.458
POND 1 IN POND 100 2.593
POND 1 OUT POND 100 2.458
2.302
Max
Qpeak Qpeak Max WSEL Pond
hrs
--------- cfs ft ac-ft
-------- -------- -------
11.9000 46.90
12.0500 26.33
11.9000 46.90
12.0500 26.33 269.79
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/Z007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 1
Q100 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Page 2.01
Storm Tag Name = 100-Ye
-----------------------------------------------------------------
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 100 yr
Total Rainfall Depth= 8.0000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 100-Ye Event: 100 yr
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 100-Ye
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration = 24.0000 hrs Rain Depth = 8.0000 in
' Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
' HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
CALCS\
HYG File - ID = - BASIN D.A. 100-Ye
Tc (Min. Tc) = .0833 hrs
Drainage Area = 6.900 acres Runoff CN= 70
' Computational Time Increment .01111 hrs
Computed Peak Time 11.9175 hrs
Computed Peak Flow 48.81 cfs
' Time Increment for HYG File = .0500 hrs
Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output = 46.90 cfs
--------------------------------------------
' DRAINAGE AREA
-------------------
' ID:None Selected
CN 70
Area 6.900 acres
S = 4.2045 in
' 0.2S = .8409 in
Cumulative Runoff
-------------------
4.5102 in
' 2.593 ac-ft
HYG Volume... 2.593 ac-ft (area under HYG curve)
***** UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: None Selected)
Computational Incr, Tm = .01111 hrs = 0.20000 Tp
' Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
Receding/Rising, Tr/Tp 1.6698 (solved from K = .7491)
' Unit peak, qp = 93.85 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Vol: Elev-Area
Name.... POND 1
Page 4.01
File.... R:\2006JOBS \06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS ,
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 1
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft) (sq.in) (acres)
--- (acres)
----------------- (ac-ft)
--------- (ac-ft)
-------------
-----------
262.00 -------------------
----- .1180 .0000 .000 .000
264.00 ----- .1788 .4421 .295 .295
266.00 ----- .2577 .6512 .434 .729
268.00 ----- .4498 1.0480 .699 1.427
270.00 ----- .5379 1.4796 .986 2.414
271.00 ----- .5968 1.7013 .567 2.981
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: EL1, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for EL1, EL2, respectively
Volume = Incremental volume between EL1 and EL2
5/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (7860 Compute Time: 10:23:59 Date: 07/14/2007
Type.... Outlet Input Data Page 5.01
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 262.00 ft
Increment = .50 ft
Max. Elev.= 271.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
< --- > Forward and Revers e Both Allowed
Structure No. Outfall E1, ft
- - E2, ft
--------
----------------- -
Stand Pipe ---
SP ---> -------
CV --------
269.200 271.000
Orifice-Circular OR ---> CV 267.500 271.000
Culvert-Circular CV ---> TW 261.500 271.000
Weir-Rectangular WR ---> TW 269.600 271.000
TW SETUP, DS Channel
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 '
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS

- WET DETENTION BASIN 1 (Q100 ANA
LYSIS - 7-14-07).PPW ,
OUTLET STRUCTURE INPUT DATA ,
Structure ID = SP ,
Structure Type = Stand Pipe
-------------
----------------
# of Openings -------
= 1 '
Invert Elev. = 269.20 ft
Diameter = 4.0000 ft
Orifice Area 12.5664 sq.ft

Orifice Coeff.
_ .600 ,
Weir Length 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000

K, Reverse
= 1.000 '
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000 ,
Structure ID = OR '
Structure Type = Orifice-Circular
---------------
----------------
# of Openings -----
= 1

Invert Elev.
= 267.50 ft '
Diameter = .1700 ft
Orifice Coeff. _ .600
S/N: 621 802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007 '
Type.... Outlet Input Data
Name.... OUTLET
Page 5.03
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
' Structure ID = CV
Structure Type = Culvert-Circular
------------------------------------
No. Barrels 1
Barrel Diameter 1.5000 ft
Upstream Invert 261.50 ft
Dnstream Invert = 260.50 ft
Horiz. Length _ 100.00 ft
Barrel Length 100.01 ft
Barrel Slope = .01000 ft/ft
' OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entrance loss)
Kb .018213 (per ft of full flow)
Kr .5000 (reverse entrance loss)
HW Convergence = .001 +/- 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) = 1.155
' T2 ratio (HW/D) 1.302
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 = 263.23 ft --> Flow = 7.58 cfs
At T2 Elev = 263.45 ft -- >' Flow = 8.66 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Outlet Input Data Page 5.04 '
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
269.60 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Composite Rating Curve
Name.... OUTLET
Page 5.05
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q
Elev. Q
ft cfs
--------
262.00 -------
.00
262.50 .00
263.00 .00
263.50 .00
264.00 .00
264.50 .00
265.00 .00
265.50 .00
266.00 .00
266.50 .00
267.00 .00
267.50 .00
268.00 .07
268.50 .10
269.00 .13
269.20 .14
269.50 6.34
269.60 9.69
270.00 44.78
270.50 99.53
271.00 172.43
Notes
------ -- Converge ------- ------------------
TW El ev Error
ft +/-ft Contrib uting Structures
--
-------
------
Free -- -----
Outfall --------
(no Q: --------
-
SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall (no Q: SP,OR,CV,WR)
Free Outfall OR,CV (no Q: SP,WR)
Free Outfall OR,CV (no Q: SP,WR)
Free Outfall OR,CV (no Q: SP,WR)
Free Outfall OR,CV (no Q: SP,WR)
Free Outfall SP,OR,C V (no Q: WR)
Free Outfall SP,OR,C V (no Q: WR)
Free Outfall SP,CV,W R (no Q: OR)
Free Outfall SP,CV,W R (no Q: OR)
Free Outfall SP,CV,W R (no Q: OR)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01
Name.... POND 1 OUT Tag: 100-Ye Event: 100 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 1 (Q100 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 100-Ye
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - POND 1 IN 100-Ye
Outflow HYG file = NONE STORED - POND 1 OUT 100-Ye
Pond Node Data = POND 1
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 267.50 ft
Starting Volume = 1.216 ac-ft
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 46.90 cfs at 11.9000 hrs
Peak Outflow = 26.33
---- cfs at 12.0500 hrs
-----------------------
-----
Peak --------------
Elevation = -------
269.79 ft
Peak Storage = 2.302 ac-ft
MASS BALANCE (ac-ft)
------
-------------
+ Initial Vol -------
= 1.216
+ HYG Vol IN = 2.593
- Infiltration = .000
- HYG Vol OUT = 2.458
- Retained Vol = 1.348
Unrouted Vol = -.003 ac-ft
(.118% of Inflow Volume)
S/N: 62180250GA84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
Appendix A
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 100-Ye... 3.01
----- 0 -----
OUTLET... 5.01, 5.05
----- P -----
POND 1... 4.01, 6.01
----- R -----
Raleigh... 2.01
----- W -----
Watershed... 1.01
A-1
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:23:59 Date: 07/14/2007
1
G'
0

L

' APPENDIX D
' SUMMARY OF ROUTING
CALCULATIONS FOR WET
' DETENTION BASIN NO.2
FOR THE Q2, Q10 AND Q100
STORMS USING PONDPACK
' COMPUTER SOFTWARE BY
HAESTAD METHODS
1
Colonial Grand - Stormwater Calcs. 10 7/14/2007
Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
--------------------------
--------------------------
JOB TITLE
--------------------------
--------------------------
COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 2
Q2 ROUTING CALCULATIONS
The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Table of Contents
Table of Contents
i
********************** MASTER SUMMARY ******************:***
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A....... 2-Year
SCS Unit Hyd. Summary .............. 3.01
********************:** POND VOLUMES ***********************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.04
*****s:********s*s****s POND ROUTING *****s***************:*
SED. BASIN 2 OUT 2-Year
Pond Routing Summary .............. 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
1
1
1
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event in Type RNF File RNF ID
------------
2-Year ------ ---------------- --------
3.6000 Synthetic Curve SCSTYPES ----------------
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= 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
-------- -------- ---------
BASIN D.A. AREA 2 2.573 11.9000 45.55
*DISCH ARGE PT 3 JCT 2 2.155 18.4000 .66
SED. BASIN 2 IN POND 2 2.573 11.9000 45.55
SED. BASIN 2 OUT POND 2 2.155 18.4000 .66 279.51
3.173
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 2
Q2 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Storm Tag Name = 2-Year
Page 2.01
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 2 yr
Total Rainfall Depth= 3.6000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 2-Year Event: 2 yr
File.... R:1200610BS106678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
' - WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 2-Year
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 2 year storm
Duration = 24.0000 hrs Rain Depth = 3.6000 in
' Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
' HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
CALCS\
HYG File - ID - BASIN D.A. 2-Year
Tc (Min. Tc) = .0833 hrs
' Drainage Area = 11.300 acres Runoff CN= 92
--------------------------------------------
--------------------------------------------
Computational Time Increment = .01111 hrs
' Computed Peak Time 11.9175 hrs
Computed Peak Flow 46.78 cfs
' Time Increment for HYG File .0500 hrs
Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output 45.55 cfs
--------------------------------------------
--------------------------------------------
DRAINAGE AREA
ID:None Selected
CN = 92
Area = 11.300 acres
S = .8696 in
0.2S = .1739 in
Cumulative Runoff
-------------------
2.7325 in
2.573 ac-ft
HYG Volume... 2.573 ac-ft (area under HYG curve)
***** UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: None Selected)
'
Compu tational Incr, Tm = .01111 hrs = 0. 20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
'
Reced ing/Rising, Tr/ Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 153.70 cfs
' Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Vol: Elev-Area Page 4.01 ,
Name.... POND 1
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 2
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft) (sq.in) (acres)
----------------
--- (acres)
----------------- (ac-ft)
--------- (ac-ft)
-------------
------------
270.00 -
-
----- .1037 .0000 .000 .000
272.00 ----- .1584 .3903 .260 .260
274.00 ----- .3106 .6908 .461 .721
276.00 ----- .4158 1.0858 .724 1.445
278.00 ----- .5019 1.3745 .916 2.361
280.00 ----- .5971 1.6464 1.098 3.459
282.00 ----- .7101 1.9584 1.306 4.764
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (1/3) * (E L2-ELI) * (Areal + Areal + sq.rt. (Areal*Area2))
where: EL1, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for EL1, EL2, respectively
Volume = Incre mental volume between EL1 and EL2
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Outlet Input Data Page 5.01
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 270.00 ft
Increment = .50 ft
Max. Elev.= 282.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
< --- > Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
Weir-Rectangular WR ---> TW 280.500 282.000
Stand Pipe SP ---> CV 279.500 282.000
Orifice-Circular OR ---> CV 275.000 282.000
Culvert-Circular CV ---> TW 269.500 282.000
TW SETUP, DS Channel
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 '
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS I
- WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
280.50 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = SP
Structure Type = Stand Pipe
-----------------
# of Openings -------------
= 1 ------
Invert Elev. = 279.50 ft
Diameter = 4.0000 ft
Orifice Area = 12.5664 sq.ft
Orifice Coeff. _ .600
Weir Length = 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 275.00 ft
Diameter = .2080 ft
Orifice Coeff. _ .600
S/N: 62180250GA84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Outlet Input Data Page 5.03
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
' OUTLET STRUCTURE INPUT DATA
' Structure ID = CV
Structure Type = Culvert-Circular
------------------------------------
' No. Barrels 1
Barrel Diameter 1.5000 ft
Upstream Invert 269.50 ft
Dnstream Invert = 264.00 ft
Horiz. Length 150.00 ft
Barrel Length 150.10 ft
Barrel Slope - .03667 ft/ft
' OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entrance loss)
Kb .018213 (per ft of full flow)
Kr .5000 (reverse entrance loss)
HW Convergence .001 +/- 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) = 1.142
T2 ratio (HW/D) = 1.288
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 = 271.21 ft ---> Flow = 7.58 cfs
At T2 Elev = 271.43 ft ---> Flow = 8.66 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
5/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
' Type.... Composite Rating Curve
Name.... OUTLET
Page 5.04
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
' ***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ------ -- Converge ------- ------------------
Elev. Q TW El ev Error
ft cfs ft +/-ft Contrib uting Structures
--------
270.00 -------
.00 ------
Free -- -----
Outfall --------
(no Q: ------------------
WR,SP,OR,CV)
270.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
'
274.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
274.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
275.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
275.50 .10 Free Outfall OR,CV (no Q: WR,SP)
276.00 .15 Free Outfall OR,CV (no Q: WR,SP)
276.50 .19 Free Outfall OR,CV (no Q: WR,SP)
277.00 .23 Free Outfall OR,CV (no Q: WR,SP)
'
277.50 .25 Free Outfall OR,CV (no Q: WR,SP)
278.00 .28 Free Outfall OR,CV (no Q: WR,SP)
278.50 .30 Free Outfall OR,CV (no Q: WR,SP)
' 279.00 .32 Free Outfall OR,CV (no Q: WR,SP)
279.50 .34 Free Outfall OR,CV (no Q: WR,SP)
280.00 13.69 Free Outfall SP,OR,C V (no Q: WR)
280.50 26.68 Free Outfall SP,CV (no Q: WR,OR)
'
281.00 58.95 Free Outfall WR,SP,C V (no Q: OR)
281.50 117.56 Free Outfall WR,SP,C V (no Q: OR)
282.00 193.33 Free Outfall WR,SP,C V (no Q: OR)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01 I
Name.... SED. BASIN 2 OUT Tag: 2-Year Event: 2 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q2 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 2-Year
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - SED. BASIN 2 IN 2-Year
Outflow HYG file = NONE STORED - SED. BASIN 2 OUT 2-Year
Pond Node Data = SED. BASIN 2
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 275.00 ft
Starting Volume = 1.056 ac-ft
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 45.55 cfs at 11.9000 hrs
Peak Outflow = .66 cfs at 18.4000 hrs
--------
----
Peak ---------------
Elevation = -----------
279.51 ---------------
ft
Peak
----
---- Storage =
---------------
--------------- 3.173
-----------
----------- ac-ft
-----------------------
-----------------------
MASS BALANCE (ac-ft)
-------------
+ Initial Vol -------------
= 1.056
+ HYG Vol IN = 2.573
- Infiltration = .000
- HYG Vol OUT = 2.155
- Retained Vol = 1.474
Unrouted Vol = -.001 ac-ft
(.024% of Inflow Volume)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
Appendix A
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 2-Year... 3.01
----- 0 -----
OUTLET... 5.01, 5.04
----- P -----
POND 1... 4.01
----- R -----
Raleigh... 2.01, 6.01
----- W -----
Watershed... 1.01
A-1
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:34:14 Date: 07/14/2007
' Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
' Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
JOB TITLE
COLONIAL GRAND AT WAKEFIELD APARTMENTS
' WET DETENTION BASIN NO. 2
Q10 ROUTING CALCULATIONS
' The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
' post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
' calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
' discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Table of Contents
Table of Contents
i
**********:*********** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A....... 10-Yea
SCS Unit Hyd. Summary .............. 3.01
**s******************** POND VOLUMES *****:*****************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.04
**********************s POND ROUTING **************s********
SED. BASIN 2 OUT 10-Yea
Pond Routing Summary ............... 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
1

1
1
1
1
1
1
1
1
1
1
1
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event RNF File
in RNF ID
------------
10-Yea ---------------- --------
------ --------
5.3800 Synthetic Curve SCSTYPES -----
--------
TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= 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
-------- -------- ---------
BASIN D.A. AREA 10 3.157 11.9000 57.09
*DISCH ARGE PT 3 JCT 10 2.768 13.7000 2.30
SED. BASIN 2 IN POND 10 3.157 11.9000 57.09
SED. BASIN 2 OUT POND 10 2.768 13.7000 2.30 279.57
3.208
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 2
Q10 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Storm Tag Name = 10-Yea
Page 2.01
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 10 yr
Total Rainfall Depth= 5.3800 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 10-Yea Event: 10 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
' - WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 10-Yea
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 10 year storm
Duration = 24.0000 hrs Rain Depth = 5.3800 in
' Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
' HYG Dir = R?\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
CALCS\
HYG File ID BASIN D.A. 10 Yea
Tc (Min. Tc) = .0833 hrs
' Drainage Area = 11.300 acres Runoff CN= 81
--------------------------------------------
--------------------------------------------
Computational Time Increment = .01111 hrs
Computed Peak Time 11.9175 hrs
Computed Peak Flow 59.14 cfs
' Time Increment for HYG File .0500 hrs
Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output 57.09 cfs
--------------------------------------------
--------------------------------------------
' DRAINAGE AREA
-------------------
ID:None Selected
t CN = 81
Area = 11.300 acres
S = 2.3001 in
' 0.2S = .4600 in
Cumulative Runoff
-------------------
' 3.3526 in
3.157 ac-ft
HYG Volume... 3.157 ac-ft (area under HYG curve)
' ***** UNIT HYDROGRAPH PARAMETERS *****
' Time Concentration, Tc = .08330 hrs (ID: None Selected)
Computational Incr, Tm = .01111 hrs = 0.20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
' K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
Receding/Rising, Tr/Tp = 1.6698 (solved from K = .7491)
' Unit peak, qp = 153.70 cfs
Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Type.... Vol: Elev-Area
Name.... POND 1
Page 4.01
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS '
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 2
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft) (sq.in) (acres)
----------
------ (acres)
---------------- (ac-ft)
---------- (ac-ft)
-------------
------------
270.00 ---
--
----- .1037 .0000 .000 .000
272.00 ----- .1584 .3903 .260 .260
274.00 ----- .3106 .6908 .461 .721
276.00 ----- .4158 1.0858 .724 1.445
278.00 ----- .5019 1.3745 .916 2.361
280.00 ----- .5971 1.6464 1.098 3.459
282.00 ----- .7101 1.9584 1.306 4.764
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: EL1, 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: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (7860 Compute Time: 10:32:14 Date: 07/14/2007
Type.... Outlet Input Data Page 5.01
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 270.00 ft
Increment = .50 ft
Max. Elev.= 282.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
< --- > Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
----------------- ---- ------- --------- ---------
Weir-Rectangular WR ---> TW 280.500 282.000
Stand Pipe SP ---> CV 279.500 282.000
Orifice-Circular OR ---> CV 275.000 282.000
Culvert-Circular CV ---> TW 269.500 282.000
TW SETUP, DS Channel
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 I
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS'
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
280.50 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = SP
Structure Type
----------------- = Stand Pipe
-------------
------
# of Openings = 1
Invert Elev. = 279.50 ft
Diameter = 4.0000 ft
Orifice Area = 12.5664 sq.ft
Orifice Coeff. _ .600
Weir Length = 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 275.00 ft
Diameter = .2080 ft
Orifice Coeff. _ .600
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
' Type.... Outlet Input Data Page 5.03
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
' Structure ID = CV
Structure Type = Culvert-Circular
------------------------------------
No. Barrels = 1
' Barrel Diameter 1.5000 ft
Upstream Invert 269.50 ft
Dnstream Invert = 264.00 ft
' Horiz. Length 150.00 ft
Barrel Length 150.10 ft
Barrel Slope = .03667 ft/ft
OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entrance loss)
' Kb .018213 (per ft of full flow)
Kr .5000 (reverse entrance loss)
HW Convergence .001 +/- 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) = 1.142
T2 ratio (HW/D) 1.288
'
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 = 271.21 ft --- > Flow = 7.58 cfs
At T2 Elev = 271.43 ft --> Flow = 8.66 cfs
' Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
' Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (7860 Compute Time: 10:32:14 Date: 07/14/2007
Type.... Composite Rating Curve
Name.... OUTLET
Page 5.04
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETEN TION BASIN 2 (Q1 0 ANALYSIS - 7-14-07).PPW
***** COM POSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ------ -- Converge -------------------------
'
Elev. Q TW El ev Error
ft cfs ft +/-ft Contributing Structures
--------
270.00 -------
.00 ------
Free -- -----
Outfall --------------------------
(no Q: WR,SP,OR,CV)
270.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
274.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
274.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
275.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
275.50 .10 Free Outfall OR,CV (no Q: WR,SP)
276.00 .15 Free Outfall OR,CV (no Q: WR,SP)
276.50 .19 Free Outfall OR,CV (no Q: WR,SP)
277.00 .23 Free Outfall OR,CV (no Q: WR,SP)
277.50 .25 Free Outfall OR,CV (no Q: WR,SP)
278.00 .28 Free Outfall OR,CV (no Q: WR,SP)
278.50 .30 Free Outfall OR,CV (no Q: WR,SP)
' 279.00 .32 Free Outfall OR,CV (no Q: WR,SP)
279.50 .34 Free Outfall OR,CV (no Q: WR,SP)
280.00 13.69 Free Outfall SP,OR,CV (no Q: WR)
280.50 26.68 Free Outfall SP,CV (no Q: WR,OR)
281.00 58.95 Free Outfall WR,SP,CV (no Q: OR)
281.50 117.56 Free Outfall WR,SP,CV (no Q: OR)
282.00 193.33 Free Outfall WR,SP,CV (no Q: OR)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01 i
Name.... SED. BASIN 2 OUT Tag: 10-Yea Event: 10 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q10 ANALYSIS - 7-14-07).PPW I
Storm... TypeII 24hr Tag: 10-Yea
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - SED. BASIN 2 IN 10-Yea
Outflow HYG file = NONE STORED - SED. BASIN 2 OUT 10-Yea
Pond Node Data = SED. BASIN 2
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 275.00 ft
Starting Volume = 1.056 ac-ft
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 57.09 cfs at 11.9000 hrs
Peak Outflow = 2.30 cfs at 13.7000 hrs
-----
Peak -------------
Elevation = -----------
279.57 ------------------------
ft
Peak
-----
----- Storage =
--------------
-------------- 3.208
-----------
----------- ac-fit
-----------------------
-----------------------
MASS BALANCE (ac-ft)
--------------------
+ Initial Vol = ------
1.056
+ HYG Vol IN = 3.157
- Infiltration = .000
- HYG Vol OUT = 2.768
- Retained Vol = 1.445
Unrouted Vol = -.000 ac-ft
(.001% of Inflow Volume)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007

1
1
1
1
1
1
Appendix A
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 10-Yea... 3.01
----- 0 -----
OUTLET... 5.01, 5.04
----- P -----
POND 1... 4.01
----- R -----
Raleigh... 2.01, 6.01
----- W -----
Watershed... 1.01
A-1
S/N: 62180250GA84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:32:14 Date: 07/14/2007

Job File: R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD
APARTMENTS - WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
Rain Dir: C:\HAESTAD\PPKW\RAINFALL\
JOB TITLE
--------------------------
--------------------------
COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 2
Q100 ROUTING CALCULATIONS
The following calculations are the routing calculations for the
Colonial Grand at Wakefield Apartments in Raleigh, North Carolina.
Wet Detention Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce the Q2 and Q10
post-developed discharge to less than or equal to the Q2 and Q10
pre-developed discharge for each point of discharge as required by
the City of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site stormwater
calculations were performed using the Rational Method. The
attached routing calculations were performed using the SCS
methodology. The SCS curve number was manipulated so that the
discharge for the respective storm will equal the discharge based
on the Rational Equation.
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Table of Contents
Table of Contents
i
*:******************** MASTER SUMMARY **********************
Watershed....... Master Network Summary ............. 1.01
****************** DESIGN STORMS SUMMARY *******************
Raleigh......... Design Storms ...................... 2.01
******************** RUNOFF HYDROGRAPHS ********************
BASIN D.A....... 100-Ye
SCS Unit Hyd. Summary .............. 3.01
*********************** POND VOLUMES ***********************
POND 1.......... Vol: Elev-Area ..................... 4.01
******************** OUTLET STRUCTURES *********************
OUTLET.......... Outlet Input Data .................. 5.01
Composite Rating Curve ............. 5.04
*****:************ss*s* POND ROUTING ***********************
SED. BASIN 2 OUT 100-Ye
Pond Routing Summary ............... 6.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
1
1
1

1
1
1
1
Type.... Master Network Summary Page 1.01
Name.... Watershed
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
MASTER DESIGN STORM SUMMARY
Default Network Design Storm File, ID STORMS.RNQ Raleigh
Total
Depth Rainfall
Return Event in ---------------- -------- RNF File -----RNF ID
------------ ------ -------- --------
100-Ye 8.0000 Synthetic Curve SCSTYPES TypeII 24hr
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol
Storage
Node ID
-------------- Type
--- ---- Event
------ ac-ft Trun
----------
BASIN D.A. AREA 100 4.247
*DISCHARGE PT 3 JCT 100 3.869
SED. BASIN 2 IN POND 100 4.247
SED. BASIN 2 OUT POND 100 3.869
3.343
Max
Qpeak Qpeak Max WSEL Pond
hrs
--------- cfs ft ac-ft
-------- -------- ---------
11.9000 76.80
12.4500 8.48
11.9000 76.80
12.4500 8.48 279.80
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... Design Storms
Name.... Raleigh
File.... C:\HAESTAD\PPKW\RAINFALL\STORMS.RNQ
Title... COLONIAL GRAND AT WAKEFIELD APARTMENTS
WET DETENTION BASIN NO. 2
Q100 ROUTING CALCULATIONS
The following calculations are the routing
calculations for the Colonial Grand at Wakefield
Apartments in Raleigh, North Carolina. Wet Detention
Basin Nos. 1 and 2 are designed to provide 85% TSS
removal as required by the NCDWQ and also to reduce
the Q2 and Q10 post-developed discharge to less than
or equal to the Q2 and Q10 pre-developed discharge
for each point of discharge as required by the City
of Raleigh. The basins are also designed to pass the
Q100 storm without overtopping the dam. The site
stormwater calculations were performed using the
Rational Method. The attached routing calculations
were performed using the SCS methodology. The SCS
curve number was manipulated so that the discharge
for the respective storm will equal the discharge
based on the Rational Equation.
DESIGN STORMS SUMMARY
Design Storm File,ID = STORMS.RNQ Raleigh
Storm Tag Name = 100-Ye
Page 2.01
Data Type, File, ID = Synthetic Storm SCSTYPES.RNF TypeII 24hr
Storm Frequency = 100 yr
Total Rainfall Depth= 8.0000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... SCS Unit Hyd. Summary Page 3.01
Name.... BASIN D.A. Tag: 100-Ye Event: 100 yr
File.... R:\2006JOBS\066780001CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
' - WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
Storm... TypeII 24hr Tag: 100-Ye
SCS UNIT HYDROGRAPH METHOD
STORM EVENT: 100 year storm
Duration = 24.0000 hrs Rain Depth = 8.0000 in
' Rain Dir = C:\HAESTAD\PPKW\RAINFALL\
Rain File -ID = SCSTYPES.RNF - TypeII 24hr
Unit Hyd Type = Default Curvilinear
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL
' CALCS\
HYG File - ID = - BASIN D.A. 100-Ye
Tc (Min. Tc) = .0833 hrs
' Drainage -Area -=-11300-acres
--Runoff -CN=-70-
Computational Time Increment = .01111 hrs
Computed Peak Time 11.9175 hrs
Computed Peak Flow 79.94 cfs
Time Increment for HYG File = .0500 hrs
' Peak Time, Interpolated Output = 11.9000 hrs
Peak Flow, Interpolated Output = 76.80 cfs
--------------------------------------------
--------------------------------------------
' ---DRAINAGE AREA
-------- ----
ID:None Selected
CN = 70
Area = 11.300 acres
S = 4.2045 in
' 0.2S = .8409 in
Cumulative Runoff
-------------------
4.5102 in
4.247 ac-ft
HYG Volume... 4.247 ac-ft (area under HYG curve)
' ***** UNIT HYDROGRAPH PARAMETERS *****
Time Concentration, Tc = .08330 hrs (ID: None Selected)
Computational Incr, Tm = .01111 hrs = 0.20000 Tp
Unit Hyd. Shape Factor = 483.432 (37.46% under rising limb)
' K = 483.43/645.333, K = .7491 (also, K = 2/(1+(Tr/Tp))
Receding/Rising, Tr/Tp = 1.6698 (solved from K = .7491)
Unit peak, qp = 153.70 cfs
' Unit peak time Tp = .05553 hrs
Unit receding limb, Tr = .22213 hrs
Total unit time, Tb = .27767 hrs
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... Vol: Elev-Area
Name.... POND 1
Page 4.01
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS'
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
Title... Wet Detention Basin No. 2
Elevation Planimeter Area Al+A2+sgr(Al*A2) Volume Volume Sum
(ft)
----------- (sq.in) (acres)
---------------------- (acres)
----------------- (ac-ft)
--------- (ac-ft)
-------------
270.00 ----- .1037 .0000 .000 .000
272.00 ----- .1584 .3903 .260 .260
274.00 ----- .3106 .6908 .461 .721
276.00 ----- .4158 1.0858 .724 1.445
278.00 ----- .5019 1.3745 .916 2.361
280.00 ----- .5971 1.6464 1.098 3.459
282.00 ----- .7101 1.9584 1.306 4.764
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (1/3) * (EL2-EL1) * (Areal + Area2 + sq.rt.(Areal*Area2))
where: EL1, 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: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
' Type.... Outlet Input Data Page 5.01
Name.... OUTLET
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIO NAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
' REQUESTED POND WS ELEVATIONS:
Min. Elev.= 270.00 ft
' Increment = .50 ft
Max. Elev.= 282.00 ft

OUTLET CONNECTIVITY

' ---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to UpStream)
< --- > Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
----------------- ---- ------- --------- -
Weir-Rectangular WR ---> TW 280.500 --------
282.000
' Stand Pipe SP --- > CV 279.500 282.000
Orifice-Circular OR --> CV 275.000 282.000
Culvert-Circular CV ---> TW 269.500 282.000
'
1 TW SETUP, DS Channel
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... Outlet Input Data Page 5.02 ,
Name.... OUTLET
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS I
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
OUTLET STRUCTURE INPUT DATA
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WR
Weir-Rectangular
----------------
1
280.50 ft
30.00 ft
3.000000
Weir TW effects (Use adjustment equation)
Structure ID = SP
Structure Type
----------------- = Stand Pipe
-------------
------
# of Openings = 1
Invert Elev. = 279.50 ft
Diameter = 4.0000 ft
Orifice Area = 12.5664 sq.ft
Orifice Coeff. _ .600
Weir Length = 12.57 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000
Kb,Barrel = .000000 (per ft of full flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 275.00 ft
Diameter = .2080 ft
Orifice Coeff. _ .600
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
r Type.... Outlet Input Data
Name.... OUTLET
Page 5.03
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
r OUTLET STRUCTURE INPUT DATA
r Structure ID = CV
Structure Type = Culvert-Circular
------------------------------------
No. Barrels = 1
r Barrel Diameter 1.5000 ft
Upstream Invert 269.50 ft
Dnstream Invert = 264.00 ft
' Horiz. Length 150.00 ft
Barrel Length 150.10 ft
Barrel Slope .03667 ft/ft
OUTLET CONTROL DATA...
Mannings n .0130
Ke = .5000 (forward entrance loss)
Kb = .018213 (per ft of full flow)
r Kr .5000 (reverse entrance loss)
HW Convergence .001 +/- ft
r 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) = 1.142
r T2 ratio (HW/D) 1.288
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 = 271.21 ft --- > Flow = 7.58 cfs
At T2 Elev = 271.43 ft --> Flow = 8.66 cfs
r Structure ID = TW
Structure Type = TW SETUP, DS Channel
r ------------------------------------
FREE OUTFALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
' Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .01 ft
Min. HW tolerance .01 ft
Max. HW tolerance = .01 ft
Min. Q tolerance .10 cfs
Max. Q tolerance = .10 cfs
r
S/N: 62180250GA84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... Composite Rating Curve
Name.... OUTLET
Page 5.04
' File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW
' ***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- ------ -- Converge ------- ------------------
'
Elev. Q TW Elev Error
ft
-------- cfs
------- ft
------ +/-ft
-- ----- Contrib
-------- uting Structures
------------------
270.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
270.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
271.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
272.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
273.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
'
274.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
274.50 .00 Free Outfall (no Q: WR,SP,OR,CV)
275.00 .00 Free Outfall (no Q: WR,SP,OR,CV)
t 275.50 .10 Free Outfall OR,CV (no Q: WR,SP)
276.00 .15 Free Outfall OR,CV (no Q: WR,SP)
276.50 .19 Free Outfall OR,CV (no Q: WR,SP)
277.00 .23 Free Outfall OR,CV (no Q: WR,SP)
'
277.50 .25 Free Outfall OR,CV (no Q: WR,SP)
278.00 .28 Free Outfall OR,CV (no Q: WR,SP)
278.50 .30 Free Outfall OR,CV (no Q: WR,SP)
279.00 .32 Free Outfall OR,CV (no Q: WR,SP)
279.50 .34 Free Outfall OR,CV (no Q: WR,SP)
280.00 13.69 Free Outfall SP,OR,C V (no Q: WR)
280.50 26.68 Free Outfall SP,CV (no Q: WR,OR)
281.00 58.95 Free Outfall WR,SP,C V (no Q: OR)
281.50 117.56 Free Outfall WR,SP,C V (no Q: OR)
282.00 193.33 Free Outfall WR,SP,C V (no Q: OR)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
' PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Type.... Pond Routing Summary Page 6.01 I
Name.... SED. BASIN 2 OUT Tag: 100-Ye Event: 100 yr
File.... R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\WAKEFIELD APARTMENTS
- WET DETENTION BASIN 2 (Q100 ANALYSIS - 7-14-07).PPW I
Storm... TypeII 24hr Tag: 100-Ye
LEVEL POOL ROUTING SUMMARY
HYG Dir = R:\2006JOBS\06678000\CALCULATIONS\PONDPACK\RATIONAL CALCS\
Inflow HYG file = NONE STORED - SED. BASIN 2 IN 100-Ye
Outflow HYG file = NONE STORED - SED. BASIN 2 OUT 100-Ye
Pond Node Data = SED. BASIN 2
Pond Volume Data = POND 1
Pond Outlet Data = OUTLET
No Infiltration
INITIAL CONDITIONS
Starting WS Elev = 275.00 ft
Starting Volume = 1.056 ac-ft
Starting Outflow = .00 cfs
Starting Infiltr. _ .00 cfs
Starting Total Qout= .00 cfs
Time Increment = .0500 hrs
INFLOW/OUTFLOW HYDROGRAPH SUMMARY
Peak Inflow = 76.80 cfs at 11.9000 hrs
Peak Outflow = 8.48 cfs at 12.4500 hrs
-------
-----
Peak --------------
Elevation = -----------
279.80 ----------------
ft
Peak Storage = 3.343 ac-ft
MASS BALANCE (ac-ft)
-------------
+ Initial Vol -------------
= 1.056
+ HYG Vol IN = 4.247
- Infiltration = .000
- HYG Vol OUT = 3.869
- Retained Vol = 1.434
Unrouted Vol = -.000 ac-ft
(.008% of Inflow Volume)
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007
Appendix A
A-1
Index of Starting Page Numbers for ID Names
----- B -----
BASIN D.A. 100-Ye... 3.01
----- 0 -----
OUTLET... 5.01, 5.04
----- P -----
POND 1... 4.01
----- R -----
Raleigh... 2.01, 6.01
----- W -----
Watershed... 1.01
S/N: 621802506A84 Bass Nixon & Kennedy Inc
PondPack Ver. 7.5 (786c) Compute Time: 10:38:11 Date: 07/14/2007