20020831 Ver 2_Stormwater Plans_20071205

,~
~~; /-..
~~31 ~ ~ 't~ ~"~~
b ~- - -~ r ta,~
d~i
WITHERS ~r R A V E N E L ~?~' ~'~`~q;~ ~~oi L."'
,~rQ~~ p~`/,Y
~~
H
STORMWATER MANAGEMENT PLAN
THE PARK AT LANGSTON
Cary, North Carolina
Prepared For.
The Park at Langston, LLC
i4oi Sunday Drive, Suite ii6
Raleigh, NC 27307
Prepared By:
WITHERS & RAVENEL, INC
iil MacKenan Drive
Cary, North Carolina 27511
duly, zoos
W&R Project No. o2o6i6o1
~Qp~6S8%py ~'y.~
~Q SEAL ~'~ '~
~ 28421
'~~ql".~INE~yy~°
I~o1
Q
C. Heath Wadsworth, PE

THE PARK AT LANGSTON
STORMWATER MANAGEMENT PLAN
CARY, NORTH CAROLINA
INTRODUCTION
The purpose of this study is to document pre- and post-development peak stormwater discharges
for the i-year storm event and to evaluate the affect ofthe ioo-year design storm on the proposed
stormwater management devices. The 1o-year design storm was also analyzed for erosion control
design purposes. The goal is to provide detention structures adequate to maintain a discharge less
than or equal to the 1-year pre-development peak discharge after the site has been developed.
The site is located in the Neuse River Basin and has one stream with a ioo ft buffer, which runs
north to south on the western side of the site. There are five stormwater Best Management Practices
(BMPs) proposed forthe site to meet peak attenuation requirements. The proposed BMPs are one
wet detention basin and one constructed wetland, which are sized according to the Division of
Water Quality surface area requirements. The other three proposed BMPs are underground pipe
detention, which are designed to meet peak attenuation requirements.
METHODOLOGY
The stormwater study was conducted using the natural drainage features as depicted by the Wake
County aerial topographic information (2-ft contours), field survey data and proposed development
within the drainage areas.
The Park at Langston i W&R Project ozo6i6oi
Stormwater Management Report July X007
Fgure i. Site outlined in red on 2005 Aerial Photography

THE PARK AT LANGSTON
STORMWATER MANAGEMENT PLAN
CARY, NORTH CAROLINA
The scope of work included the following analyses:
Hyd rolo>;y
^ Simulation of the i-year, io-year, and soo-year rainfall events for the Cary area
^ Formulation of the 1-year, so-year, and ioo-year flood hydrographs for the pre- and post-
developmentdrainage areas
Hydraulic
^ Routing the i-year, io-year, and soo-year flood hydrographs for post development runoff
through the proposed stormwater BMPs
The results ofthe hydrologic calculations are used in the hydraulic analyses. The hydraulic design
requires the development of stage-storage and stage-discharge functions for the wet detention
basins. The rainfall/runoff hydrographs, stage-storage and stage-discharge functions have been
compiled to create a routing computer simulation model using Haestad Methods PondPack vio.o
software. This PondPack model was then used to assess the impact of the peak discharges for the
design rainfall events. The PondPack modeling results are provided as appendices to this report.
HYDROLOGY
The SCS Method was used to develop runoff hydrographs for the 1-year, so-year, and loo-year storm
events. NOAA Atlas i4 rainfall data for Raleigh-Durham International Airport was used to determine
the 2q-hour duration rainfall for the so-year and ioo-year storm events. The 1-year storm event was
modeled using the SCS Type II, 24-hour, rainfall curve with a 3.0" total depth. This method requires
three basic parameters: a curve number (CN), time of concentration (t~, and drainage area.
Curve numbers were based on soil type and land use. Soil types were delineated from the Soil
Survey of Wake County, North Carolina (November i97o). Land use data was determined using aerial
photography and the most recent site plans for the proposed site. The curve numbers used in this
study are listed in the appendix of this report.
Times of concentration were calculated using methods described in the SCS publication "Urban
Hydrology for Small Watersheds, TR-55" and based on natural drainage patterns and field survey
data. For post-development drainage areas that had shorter flow paths, the time of concentration
was assumed to be 5 minutes.
HYDRAULICS
Computer simulated reservoir routing of the 1-year, io-year, and loo-year design storms utilized
stage-storage and stage-discharge functions. Stage-storage functions were derived from the
proposed contours for the wet detention basins, and from the pipe length and cross section for the
pipe underground storage devices. Anon-linear regression relation for surface area versus elevation
was derived for the BMPs. This relation estimates the incremental volume of the basin to the stage
or elevation of the basins. Stage-discharge functions were developed to size the outlet structure for
the wet pond and stormwater wetland.
CONCLUSIONS
Based on the routing study, the post development peak discharge from the entire site is less than
the pre-development peak for the i-year design storms. Table s below summarizes the peak
attenuation results. The wet detention basin and constructed wetland contained the discharge from
The Park at Langston z W&R Project ozo6i6oi
stormwater Management Report luly zoo?

THE PARK AT LANGSTON
STORMWATER MANAGEMENT PLAN
CARY, NORTH CAROLINA
the loo-year storm without overtopping. Tables z through 4 summarize the design for the outlets of
the BMPs.
The resulting post development nitrogen export for the site is below the 3.6 lbs/acre/year maximum
nitrogen loading allowed in the Neuse River Basin for residential development. The nitrogen export
calculations are provided in an appendix to this report.
TABLE i. PEAK ATTENUATION SUMMARY FOR THE i-YEAR,10-YEAR, AND 100-YEAR DESIGN STORM
1-year ~eak io-year QQeak loo-year Q~eak
Pre-Development 8.11 cfs 34.17 cfs 64.67 cfs

Post-Development
BMP 1 -Wet Detention Basin -Out o.46 cfs 16.2o cfs 29.36 cfs
BMP 2 -Constructed Wetland -Out o.i8 cfs 7.52 cfs 12.73 cfs
BMP 3 -Underground Pipe Detention (#1) -Out o.13 cfs 1.83 cfs 2.98 cfs
BMP 4 -Underground Pipe Detention (#2) -Out o.35 cfs 3.83 cfs 4.35 cfs
BMP 5 -Underground Pipe Detention (#3) -Out o.3o cfs 6.01 cfs 8.23 cfs
Untreated 7.64 cfs 24.36 cfs 39.19 cfs
Post-Development Total 8.07 cfs 40.48 cfs 84.52 cfs
TABLE 2. BMP 1(WET DETENTION BASIN) DESIGN SUMMARY
Bottom of Pond 362.00'
Top of Dam 368.00'
Drawdown/Atten. Orifice 2" Diameter at 365.00'
Riser 5' x 5' -Crest at 366.50'
Outlet Barrel 30" RCP - 50.o LF at 1.0%
loo-year WSEL 367.11'
The Park at Langston 3 W&R Project ozo6i6oi
Stormwater Management Report July zoo?

THE PARK AT LANGSTON
STORMWATER MANAGEMENT PLAN
GARY, NORTH CAROLINA
TABLE 3. BMP 2 (CONSTRUCTED WETLAND) DESIGN SUMMARY
Bottom of Wetland 369.00'
Top of Dam 373.00'
Drawdown/Atten. Orifice i" Diameter at 370.50'
Riser 4' x 4' -Crest at 37i.7o'
Outlet Barrel 24" RCP - 52 LF at o.4%
ioo-year WSEL 372.io'
TABLE!}. BMP 3, 4, AND 5 (UNDERGROUND PIPE DETENTION) DESIGN SUMMARY
BMP 3 (UPD #1) BMP 4 (UPD #2) BMP 5 (UPD #3)
Pipe Invert 364.00' 37i.oo' 370.00'
Pipe Size 36" - zio LF 36" - i9o LF 2 c@ 36" - 22o LF ea
Drawdown/Atten.
Orifice 2" Diameter at 364.00' 1" Diameter at 37i.oo' 3" Diameter at 370.00'
Weir 3' -Crest at 366.40' 3' -Crest at 373.40' 3' -Crest at 372.io'
Outlet Barrel i5" RCP 18" RCP 24" RCP
The Park at Langston q W&R Project o2o6i6oi
Stormwater Management Report July zoo?

BASIN
Off-site (3/4 f
w. DA=2.E
Channel
TRUELOVE
p �a
+ UNDERGROUND PIPE DETENTIO
igo LF- 36" PIPE
r
ention (UGD #2) DA
`: -4.'
v ,w'
ention (UGD #3) DA,
ter Wetland DA
J DA
F
lv
ite_pond
IUND PIPE DETENTION #i
'PIPE
DA=0.55ac
BASIN
Off-site (3/4 f
w. DA=2.E
Channel
TRUELOVE
p �a
+ UNDERGROUND PIPE DETENTIO
igo LF- 36" PIPE

DISCHARGE SUMMARY

Type.... Master Network Summary Paqe 2.01
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
MASTER DESIGN STORM SUMMARY
Network Storm Collection: RDU NOAA 14 Desi
Total
Depth
Return Event in
2 3.4400
5 4.3000
10 4.9800
25 5.9000
50 6.6300
100 7.3700
1 3.0000
Rainfall
Type
----------------
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Time-Depth Curve
Synthetic Curve
RNF ID
RDU NOAA 2yr
RDU NOAA Syr
RDU NOAA l0yr
RDU NOAA 25yr
RDU NOAA 50yr
RDU NOAA 100yr
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
Node
----- ID
---------
--- Type
---- Event
------
CON. WETLAND IN POND 2
CON. WETLAND IN POND 5
CON. WETLAND IN POND 10
CON. WETLAND IN POND 25
CON. WETLAND IN POND 50
CON. WETLAND IN POND 100
CON. WETLAND IN POND 1
HYG Vol
ac-ft Trun
.230
.359
.471
.632
.766
.905
.170
Qpeak Qpeak
hrs cfs
---------
12.1000 --------
4.39
12.1000 6.64
12.1000 8.47
12.1000 10.63
12.1000 12.07
12.1000 13.39
11.9500 2.85
Max
Max WSEL Pond Storage
ft ac-ft
-------- ------------
CON. WETLAND OUT POND 2 .226 12.4500 .90 371.77 .182
CON. WETLAND OUT POND 5 .355 12.2000 4.64 371.90 .194
CON. WETLAND OUT POND 10 .467 12.1500 7.52 371.98 .201
CON. WETLAND OUT POND 25 .628 12.1500 9.96 372.04 .206
CON. WETLAND OUT POND 50 .761 12.1500 11.33 372.07 .209
CON. WETLAND OUT POND 100 .901 12.1500 12.73 372.10 .212
CON. WETLAND OUT POND 1 .166 13.5000 .18 371.71 .178
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:16 AM 7/11/2007

Type.... Master Network Summary Page 2.02
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(T run= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Return HYG Vol Qpeak Qpeak
Node ID - Type Event ac-ft Trun hrs cfs
----
DA ------------
#1 TREATED - ----
AREA ------
2 ---------- --
.650 ---------
12.2000 --------
9.38
DA #1 TREATED AREA 5 1.026 12.2000 14.51
DA #1 TREATED AREA 10 1.353 12.2000 18.55
DA #1 TREATED AREA 25 1.824 12.2000 23.41
DA #1 TREATED AREA 50 2.217 12.2000 26.93
DA #1 TREATED AREA 100 2.629 12.2000 30.35
DA #1 TREATED AREA 1 .478 12.0500 6.53
DA #lA TREATED AREA 2 .050 12.1000 1.05
DA #lA TREATED AREA 5 .078 12.1000 1.55
DA #lA TREATED AREA 10 .102 12.1000 1.95
DA #lA TREATED AREA 25 .136 12.1000 2.42
DA #lA TREATED AREA 50 .164 12.1000 2.72
DA #lA TREATED AREA 100 .194 12.1000 3.04
DA #lA TREATED AREA 1 .038 11.9500 .65
DA #2 TREATED AREA 2 .230 12.1000 4.39
DA #2 TREATED AREA 5 .359 12.1000 6.64
DA #2 TREATED AREA 10 .471 12.1000 8.47
DA #2 TREATED AREA 25 .632 12.1000 10.63
DA #2 TREATED AREA 50 .766 12.1000 12.07
DA #2 TREATED AREA 100 .905 12.1000 13.39
DA #2 TREATED AREA 1 .170 11.9500 2.85
DA #2A TREATED AREA 2 .105 12.1000 2.18
DA #2A TREATED AREA 5 .162 12.1000 3.20
DA #2A TREATED AREA 10 .211 12.1000 4.03
DA #2A TREATED AREA 25 .281 12.1000 5.01
DA #2A TREATED AREA 50 .340 12.1000 5.64
DA #2A TREATED AREA 100 .401 12.1000 6.30
DA #2A TREATED AREA 1 .078 11.9500 1.35
Max
Max WSEL Pond Storage
ft ac-ft
-------- ------------
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:16 AM
Withers & Ravenel
7/11/2007

Type.... Master Network Summary Page 2.03
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
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 Qpeak
Node
------ ID
---------- Type
- -- Event ac-ft Trun hrs

DA
#3
TREATED --
AREA ------
2 ---------- --
.182 ---------
12.1500
DA #3 TREATED AREA 5 .282 12.1500
DA #3 TREATED AREA 10 .367 12.1500
DA #3 TREATED AREA 25 .490 12.1500
DA #3 TREATED AREA 50 .592 12.1500
DA #3 TREATED AREA 100 .698 12.1500
DA #3 TREATED AREA 1 .136 12.0000
Max
Qpeak Max WSEL Pond Storage
cfs ft ac-ft
-------- -------- ------------
3.31
4.85
6.05
7.45
8.42
9.49
2.23
DA UNTREATED AREA 2 .619 12.1000 12.62
DA UNTREATED AREA 5 .978 12.1000 19.17
DA UNTREATED AREA 10 1.289 12.1000 24.52
DA UNTREATED AREA 25 1.738 12.1000 30.88
DA UNTREATED AREA 50 2.112 12.1000 35.06
DA UNTREATED AREA 100 2.504 12.1000 39.45
DA UNTREATED AREA 1 .455 11.9500 7.69
*OUT POST JCT 2 1.824 12.1000 13.05
*OUT POST JCT 5 2.873 12.2000 24.56
*OUT POST JCT 10 3.781 12.2000 40.48
*OUT POST JCT 25 5.082 12.1500 64.22
*OUT POST JCT 50 6.196 12.1000 75.53
*OUT POST JCT 100 7.340 12.1000 84.52
*OUT POST JCT 1 1.343 11.9500 8.07
*OUT PRE JCT 2 .969 12.2000 13.61
*OUT PRE JCT 5 1.694 12.2000 24.54
*OUT PRE JCT 10 2.353 12.1500 34.17
*OUT PRE JCT 25 3.336 12.1500 46.60
*OUT PRE JCT 50 4.178 12.1500 55.68
*OUT PRE JCT 100 5.075 12.1500 64.67
*OUT PRE JCT 1 .657 12.0500 8.11
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:16 AM 7/11/2007

Type.... Master Network Summary Page 2.04
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
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
------------
-----------------
PRE-DEVELOPMENT ----
AREA ------
2 ----------
.969 -- ---------
12.2000 --------
13.61 --
-
PRE-DEVELOPMENT AREA 5 1.694 12.2000 24.54
PRE-DEVELOPMENT AREA 10 2.353 12.1500 34.17
PRE-DEVELOPMENT AREA 25 3.336 12.1500 46.60
PRE-DEVELOPMENT AREA 50 4.178 12.1500 55.68
PRE-DEVELOPMENT AREA 100 5.075 12.1500 64.67
PRE-DEVELOPMENT AREA 1 .657 12.0500 8.11
U.G. DET. #2 IN POND 2 .105 12.1000 2.18
U.G. DET. #2 IN POND 5 .162 12.1000 3.20
U.G. DET. #2 IN POND 10 .211 12.1000 4.03
U.G. DET. #2 IN POND 25 .281 12.1000 5.01
U.G. DET. #2 IN POND 50 .340 12.1000 5.64
U.G. DET. #2 IN POND 100 .401 12.1000 6.30
U.G. DET. #2 IN POND 1 .078 11.9500 1.35
U.G. DET. #2 OUT POND 2 .104 12.2000 1.87 373.74 .030
U.G. DET. #2 OUT POND 5 .162 12.1000 2.91 373.86 .030
U.G. DET. #2 OUT POND 10 .211 12.1000 3.83 373.95 .031
U.G. DET. #2 OUT POND 25 .274 R 12.1000 4.35 374.00 .031
U.G. DET. #2 OUT POND 50 .334 R 12.1000 4.35 374.00 .031
U.G. DET. #2 OUT POND 100 .397 R 12.0500 4.35 374.00 .031
U.G. DET. #2 OUT POND 1 .078 12.1500 .35 373.50 .027
U.G. DET. #3 IN POND 2 .182 12.1500 3.31
U.G. DET. #3 IN POND 5 .282 12.1500 4.85
U.G. DET. #3 IN POND 10 .367 12.1500 6.05
U.G. DET. #3 IN POND 25 .490 12.1500 7.45
U.G. DET. #3 IN POND 50 .592 12.1500 8.42
U.G. DET. #3 IN POND 100 .698 12.1500 9.49
U.G. DET. #3 IN POND 1 .136 12.0000 2.23
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:16 AM
Withers & Ravenel
7/11/2007

Type.... Master Network Summary Page 2.05
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(T run= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storaqe
Node
----- ID
--------
---- Type
---- Event
------ ac-ft Trun
---------- -- hrs
--------- cfs
-------- ft
-------- ac-ft
------------
U.G. DET. #3 OUT POND 2 .182 12.3500 1.32 372.33 .059
U.G. DET. #3 OUT POND 5 .281 12.2000 4.20 372.66 .067
U.G. DET. #3 OUT POND 10 .367 12.1500 6.01 372.82 .070
U.G. DET. #3 OUT POND 25 .490 12.1500 7.82 372.97 .071
U.G. DET. #3 OUT POND 50 .614 R 12.1500 8.23 373.00 .071
U.G. DET. #3 OUT POND 100 .723 R 12.1000 8.23 373.00 .071
U.G. DET. #3 OUT POND 1 .136 12.3500 .30 371.88 .047
U.G. DET.#1 IN POND 2 .050 12.1000 1.05
U.G. DET.#1 IN POND 5 .078 12.1000 1.55
U.G. DET.#1 IN POND 10 .102 12.1000 1.95
U.G. DET.#1 IN POND 25 .136 12.1000 2.42
U.G. DET.#1 IN POND 50 .164 12.1000 2.72
U.G. DET.#1 IN POND 100 .194 12.1000 3.04
U.G. DET.#1 IN POND 1 .038 11.9500 .65
U.G. DET.#1 OUT POND 2 .050 12.3000 .41 366.49 .016
U.G. DET.#1 OUT POND 5 .078 12.1500 1.37 366.66 .017
U.G. DET.#1 OUT POND 10 .102 12.1500 1.83 366.72 .017
U.G. DET.#1 OUT POND 25 .136 12.1000 2.26 366.77 .017
U.G. DET.#1 OUT POND 50 .164 12.1000 2.75 366.83 .017
U.G. DET.#1 OUT POND 100 .193 12.1000 2.98 366.85 .018
U.G. DET.#1 OUT POND 1 .038 12.1000 .13 365.77 .011
WET POND IN POND 2 .650 12.2000 9.38
WET POND IN POND 5 1.026 12.2000 14.51
WET POND IN POND 10 1.353 12.2000 18.55
WET POND IN POND 25 1.824 12.2000 23.41
WET POND IN POND 50 2.217 12.2000 26.93
G.~T POND IN POND 100 2.629 12.2000 30.35
WE',T POND IN POND 1 .478 12.0500 6.53
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:16 AM
Withers & Ravenel
7/11/2007

Type.... Master Network Summary Page 2.06
Name.... Watershed
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
MASTER NETWORK SUMMARY
SCS Unit Hydrograph Method
(*Node=Outfall; +Node=Diversion;)
(T run= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt)
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node ID Type Event ac-ft Trun hrs
-------- cfs
-------- ft
-------- ac-ft
------------
----
WET -------
POND ------
OUT ----
POND ------
2 ---------- --
.643 -
12.6000 2.41 366.61 .625
WET POND OUT POND 5 1.019 12.3500 10.19 366.80 .661
WET POND OUT POND 10 1.345 12.3000 16.20 366.91 .683
WET POND OUT POND 25 1.817 12.2500 22.43 367.01 .702
WET POND OUT POND 50 2.210 12.2500 25.98 367.06 .713
WET POND OUT POND 100 2.621 12.2500 29.36 367.11 .722
WET POND OUT POND 1 .471 13.9500 .46 366.52 .609
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:16 AM 7/11/2007

PRE-DEVELOPMENT
CALCULATIONS

Table of Contents
Table of Contents
1
****************** DESIGN STORMS SUMMARY *******************
RDU NOAA 14 Desi Design Storms ...................... 1.01
********************** TC CALCULATIONS ****+****************
PRE-DEVELOPMENT Tc Calcs ........................... 2.01
********************** CN CALCULATIONS *********************
PRE-DEVELOPMENT Runoff CN-Area ..................... 3.01
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
4:40 PM
Withers & Ravenel
4/11/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 1.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev040907.ppw
Title... Project Date: 3/6/2007
Project Engineer: C. H. Wadsworth
Project Title: Park at Langston
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 2
Data Type, File, ID = Time-Depth Curve RDU NOAA 2yr
Storm Frequency = 2 yr
Total Rainfall Depth= 3.4400 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 5
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA Syr
5 yr
4.3000 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 10
Data Type, File, ID = Time-Depth Curve RDU NOAA l0yr
Storm Frequency = 10 yr
Total Rainfall Depth= 4.9800 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 25
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 25yr
25 yr
5.9000 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 50
Data Type, File, ID = Time-Depth Curve RDU NOAA 50yr
Storm Frequency = 50 yr
Total Rainfall Depth= 6.6300 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 1.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev040907.ppw
Title... Project Date: 3/6/2007
Project Engineer: C. H. Wadsworth
Project Title: Park at Langston
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 100
Data Type, File, ID = Time-Depth Curve RDU NOAA 100yr
Storm Frequency = 100 yr
Total Rainfall Depth= 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs
Storm Tag Name = 1
Data Type, File, ID = Synthetic Storm TypeII 24hr
Storm Frequency = 1 yr
Total Rainfall Depth= 3.0000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

Type.... Tc Calcs
Name.... PRE-DEVELOPMENT
Page 2.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev040907.ppw
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: TR-55 Sheet
Mannings n
Hydraulic Length
2yr, 24hr P
Slope
Avg.Velocity
20 ft/sec
Segment #1 Time: .1319 hrs
------------------------------------------------------------------------
Segment #2: Tc: TR-55 Shallow
Hydraulic Length
Slope
Unpaved
Avg.Velocity
.1500
93.00 ft
3.0000 in
032000 ft/ft
449.00 ft
.057900 ft/ft
3.88 ft/sec
Segment #2 Time: .0321 hrs
------------------------------------------------------------------------
-------------------------
-------------------------
Total Tc: .1640 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

Type.... Tc Calcs
Name.... PRE-DEVELOPMENT
Page 2.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev040907.ppw
Tc Equations used...
------------------------------------------------------------------------
___= SCS TR-55 Sheet Flow ______________________________________________
Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4))
Where: Tc = Time of concentration, hrs
n = Mannings n
Lf = Flow length, ft
P = 2yr, 24hr Rain depth, inches
Sf = Slope, o
___= SCS TR-55 Shallow Concentrated Flow _______________________________
Unpaved surface:
V = 16.1345 * (Sf**0.5)
Paved surface:
V = 20.3282 * (Sf**0.5)
Tc = (Lf / V) / (3600sec/hr)
Where: V = Velocity, ft/sec
Sf = Slope, ft/ft
Tc = Time of concentration, hrs
Lf = Flow length, ft
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

Type.... Runoff CN-Area
Name.... PRE-DEVELOPMENT
Page 3.01
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres oC %UC
- CN
------
--------------------------------
Impervious Areas - Paved parking lO ----
98 ---------
.340 ----- ---- 98.00
Woods - poor 66 .310 66.00
Open space (Lawns, parks etc.) - Poo 79 1.870 79.00
Woods - good 55 14.000 55.00
woods - good 77 3.280 77.00
COMPOSITE AREA & WEIGHTED CN ---> 19.800 61.82 (62)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

Appendix A
Index of Starting Page Numbers for ID Names
A-1
----- P -----
PRE-DEVELOPMENT... 2.01, 3.01
----- R -----
RDU NOAA 14 Desi... 1.01
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 4:40 PM 4/11/2007

POST DEVELOPMENT
CALCULATIONS

Table of Contents
Table of Contents (continued)
ii
U.G. DET. #2.... Vol: Pipe .......................... 4.02
U.G. DET. #3.... Vol: Pipe .......................... 4.03
U.G. DET.#1..... Vol: Pipe .......................... 4.04
WET POND........ Vol: Elev-Area ..................... 4.05
******************** OUTLET STRUCTURES *********************
Outlet con. wet. Outlet Input Data .................. 5.01
Outlet UGD #1... Outlet Input Data .................. 5.04
Outlet UGD #2... Outlet Input Data .................. 5.07
Outlet UGD #3... Outlet Input Data .................. 5.10
Outlet wet pond Outlet Input Data .................. 5.13
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 1.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
Title... Project Date: 3/6/2007
Project Engineer: C. H. Wadsworth
Project Title: Park at Langston
Project Comments:
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 2
Data Type, File, ID = Time-Depth Curve RDU NOAA 2yr
Storm Frequency = 2 yr
Total Rainfall Depth= 3.4400 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 5
Data Type, File, ID = Time-Depth Curve RDU NOAA Syr
Storm Frequency = 5 yr
Total Rainfall Depth= 4.3000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 10
Data Type, File, ID
Storm Frequency
Total Rainfall Depth
Duration Multiplier
Resulting Duration
Resulting Start Time
Time-Depth Curve RDU NOAA 10yr
10 yr
4.9800 in
1
23.9904 hrs
.0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Taq Name = 25
Data Type, F te, ID = Time-Depth Curve RDU NOAA 25yr
Storm Frequency = 25 yr
Total Rainfall Depth= 5.9000 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
Storm Tag Name = 50
Data Type, File, ID = Time-Depth Curve RDU NOAA 50yr
Storm Frequency = 50 yr
Total Rainfall Depth= 6.6300 in
Duration Multiplier = 1
Resulting Duration = 23.9904 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9904 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Design Storms
Name.... RDU NOAA 14 Desi
Page 1.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
Title... Project Date: 3/6/2007
Project Engineer: C. H. Wadsworth
Project Title: Park at Langston
Project Comments
DESIGN STORMS SUMMARY
Design Storm File,ID = RDU NOAA 14 Desi
Storm Tag Name = 100
Data Type, File, ID = Time-Depth Curve RDU NOAA 100yr
Storm Frequency = 100 yr
Total Rainfall Depth= 7.3700 in
Duration Multiplier = 1
Resulting Duration = 23.9990 hrs
Resulting Start Time= .0000 hrs Step= .0833 hrs End= 23.9990 hrs
Storm Tag Name = 1
Data Type, File, ID = Synthetic Storm TypeII 24hr
Storm Frequency = 1 yr
Total Rainfall Depth= 3.0000 in
Duration Multiplier = 1
Resulting Duration = 24.0000 hrs
Resulting Start Time= .0000 hrs Step= .1000 hrs End= 24.0000 hrs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #1 TREATED
Page 2.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: TR-55 Sheet
Mannings n .1500
Hydraulic Length 87.00 ft
2yr, 24hr P 3.0000 in
Slope .022900 ft/ft
Avq.Velocity .17 ft/sec
Segment #1 Time: .1429 hrs
Segment #2: Tc: TR-55 Shallow
Hydraulic Length 109.00 ft
Slope .018400 ft/ft
Unpaved
Avg.Velocity 2.19 ft/sec
Segment #2 Time: .0138 hrs
------------------------------------------------------------------------
Segment #3: Tc: TR-55 Channel
Flow Area
Wetted Perimeter
Hydraulic Radius
Slope
Mannings n
Hydraulic Length
2.5000 sq.ft
6.50 ft
.38 ft
.032200 ft/ft
.0300
1178.00 ft
Avg.Vrtocity 4.71 ft/sec
Segment #3 Time: .0694 hrs
------------------------------------------------------------------------
Total Tc: .2262 hrs
-------------------------
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA #1 TREATED
Page 2.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
SCS TR-55 Sheet Flow ______________________________________________
Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4))
Where: Tc = Time of concentration, hrs
n = Mannings n
Lf = Flow length, ft
P = 2yr, 24hr Rain depth, inches
Sf = Slope, a
___= SCS TR-55 Shallow Concentrated Flow _______________________________
Unpaved surface:
V = 16.1345 * (Sf**0.5)
Paved surface:
V = 20.3282 * (Sf**0.5)
Tc = (Lf / V) / (3600sec/hr)
Where: V = Velocity, ft/sec
Sf = Slope, ft/ft
Tc = Time of concentration, hrs
Lf = Flow length, ft
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA #1 TREATED
Page 2.03
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
___= SCS Channel Flow __________________________________________________
R = Aq / Wp
V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n
Tc = (Lf / V) / (3600sec/hr)
Where: R
Aq
wp
V
Sf
n
Tc
Lf
Hydraulic radius
Flow area, sq.ft.
Wetted perimeter, ft
Velocity, ft/sec
Slope, ft/ft
Mannings n
Time of concentration, hrs
Flow length, ft
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA #lA TREATED
Page 2.04
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: User Defined
Segment #1 Time: .0830 hrs
------------------------------------------------------------------------
Total Tc: .0830 hrs
Calculated Tc < Min.Tc:
Use Minimum Tc...
Use Tc = .0833 hrs
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA #lA TREATED
Paqe 2.05
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
Tc Equations used...
------------------------------------------------------------------------
___= User Defined ______________________________________________________
Tc = Value entered by user
Where: Tc = Time of concentration
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #2 TREATED
Page 2.06
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: TR-55 Sheet
Mannings n .1000
Hydraulic Length 65.00 ft
2yr, 24hr P 3.0000 in
Slope .061700 ft/ft
Avg.Velocity .33 ft/sec
Segment #1 Time: .0550 hrs
Segment #2: Tc: TR-55 Channel
Flow Area
Wetted Perimeter
Hydraulic Radius
Slope
Mannings n
Hydraulic Length
Avg.Velocity
2.5000 sq.ft
5.50 ft
.45 ft
018600 ft/ft
.0300
646.00 ft
4.00 ft/sec
Segment #2 Time: .0448 hrs
------------------------------------------------------------------------
-------------------------
-------------------------
Total Tc: .0999 hrs
-------------------------
-------------------------
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #2 TREATED
Page 2.07
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
___= SCS TR-55 Sheet Flow ______________________________________________
Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4))
Where: Tc = Time of concentration, hrs
n =Mannings n
Lf = Flow length, ft
P = 2yr, 24hr Rain depth, inches
Sf = Slope, o
SCS Channel Flow
R = Aq / Wp
V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n
Tc = (Lf / V) / (3600sec/hr)
Where: R
Aq
Wp
V
Sf
n
Tc
Lf
Hydraulic radius
Flow area, sq.ft.
Wetted perimeter, ft
Velocity, ft/sec
Slope, ft/ft
Mannings n
Time of concentration, hrs
Flow length, ft
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA #2A TREATED
Page 2.08
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: User Defined
Segment #1 Time: .0830 hrs
------------------------------------------------------------------------
------------------------
Total Tc: .0830 hrs
Calculated Tc < Min.Tc:
Use Minimum Tc...
Use Tc = .0833 hrs
-------------------------
-------------------------
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #2A TREATED
Page 2.09
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
------------------------------------------------------------------------
Tc Equations used...
___= User Defined ______________________________________________________
Tc = Value entered by user
Where: Tc = Time of concentration
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #3 TREATED
Page 2.10
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: TR-55 Sheet
Mannings n
Hydraulic Length
2yr, 24hr P
Slope
Avg.Velocity
27 ft/sec
Segment #1 Time: .0999 hrs
Segment #2: Tc: TR-55 Channel
Flow Area
Wetted Perimeter
Hydraulic Radius
Slope
Mannings n
Hydraulic Length
.1000
97.00 ft
3.0000 in
.031000 ft/ft
2.5000 sq.ft
5.50 ft
.45 ft
.026500 ft/ft
.0300
453.00 ft
Avg.Velocity 4.78 ft/sec
Segment #2 Time: .0263 hrs
------------------------------------------------------------------------
-------------------------
-------------------------
Total Tc: .1262 hrs
-------------------------
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA #3 TREATED
Page 2.11
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
------------------------------------------------------------------------
Tc Equations used...
------------------------------------------------------------------------
___= SCS TR-55 Sheet Flow _________________________________
Tc = (.007 * ((n * Lf)**0.8)) / ((P**.5) * (Sf**.4))
Where: Tc = Time of concentration, hrs
n =Mannings n
Lf = Flow length, ft
P = 2yr, 24hr Rain depth, inches
Sf = Slope, o
___= SCS Channel Flow ____________________________________________
R = Aq / Wp
V = (1.49 * (R**(2/3)) * (Sf**-0.5)) / n
Tc = (Lf / V) / (3600sec/hr)
Where: R
Aq
wp
V
Sf
n
Tc
Lf
Hydraulic radius
Flow area, sq.ft.
Wetted perimeter, ft
Velocity, ft/sec
Slope, ft/ft
Mannings n
Time of concentration, hrs
Flow length, ft
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Tc Calcs
Name.... DA UNTREATED
Page 2.12
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
........................................................................
........................................................................
TIME OF CONCENTRATION CALCULATOR
........................................................................
........................................................................
Segment #1: Tc: User Defined
Segment #1 Time: .0830 hrs
------------------------------------------------------------------------
------------------------
Total Tc: .0830 hrs
Calculated Tc < Min.Tc:
Use Minimum Tc...
Use Tc = .0833 hrs
-------------------------
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Tc Calcs
Name.... DA UNTREATED
Page 2.13
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
Tc Equations used...
___= User Defined ______________
Tc = Value entered by user
Where: Tc = Time of concentration
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Runoff CN-Area
Name.... DA #1 TREATED
Page 3.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description
---------------------------- CN acres oC °sUC CN
---- -
Residential Districts - 1/3 acre ---
72 ---------
4.930 ----- ----- ------
72.00
Open space (Lawns parks etc.) - Goo 61 .490 61.00
Residential Districts - 1 acre 68 2.610 68.00
COMPOSITE AREA & WEIGHTED CN ---> 8.030 70.03 (70)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Runoff CN-Area
Name.... DA #lA TREATED
Page 3.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres oC oUC CN
-------------------------------- ---- --------- ----- ----- ------
Residential Districts - 1/3 acre 72 .560 72.00
COMPOSITE AREA & WEIGHTED CN ---> .560 72.00 (72)
...........................................................................
...........................................................................
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Runoff CN-Area
Name.... DA #2 TREATED
Page 3.03
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description
---------------------- CN acres %C %UC CN
---------- -
woods - good ---
55 ---------
.170 ----- ----- ------
55.00
Residential Districts - 1/3 acre 72 2.370 72.00
Open space (Lawns,parks etc.) - Goo 80 .040 80.00
Open space (Lawns,parks etc.) - Goo 61 .110 61.00
COMPOSITE AREA & WEIGHTED CN --->
....................................
....................................
....
.... 2.690
..........
..........
............
............ 70.59 (71)
.............
.............
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Runoff CN-Area
Name.... DA #2A TREATED
Page 3.04
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
RUNOFF CURVE NUMBER DATA
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C °sUC CN
-------------------------------- ---- --------- ----- ----- ------
Residential Districts - 1/3 acre 72 1.160 72.00
COMPOSITE AREA & WEIGHTED CN ---> 1.160 72.00 (72)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Runoff CN-Area
Name.... DA #3 TREATED
Page 3.05
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C oUC CN
-------------------------------- ---- --------- ----- ----- ------
Residential Districts - 1/3 acre 72 2.020 72.00
COMPOSITE AREA & WEIGHTED CN ---> 2.020 72.00 (72)
...........................................................................
...........................................................................
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Runoff CN-Area
Name.... DA UNTREATED
Page 3.06
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
RUNOFF CURVE NUMBER DATA
..........................................................................
..........................................................................
Impervious
Area Adjustment Adjusted
Soil/Surface Description CN acres %C %UC
---- CN
------
-------------------------------- -
Residential Districts - 1/3 acre ---
86 ---------
.270 ----- - 86.00
Residential Districts - 1/3 acre 72 2.840 72.00
Open space (Lawns parks etc.) - Goo 61 .240 61.00
Open space (Lawns,parks etc.) - Goo 80 .270 80.00
woods - good 55 1.600 55.00
Woods - good 77 2.430 77.00
COMPOSITE AREA & WEIGHTED CN --->
....................................
....................................
....
.... 7.650
..........
..........
............
............ 70.46 (70)
.............
.............
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Vol: Elev-Area
Name.... CON. WETLAND
Page 4.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum
(ft) (sq.in) (sq.ft)
------------------- (sq.ft)
---------------- (ac-ft)
---------- (ac-ft)
-------------
------------
369.00 --
----- 2066 0 .000 .000
370.00 ----- 2630 7027 .054 .054
371.00 ----- 3232 8778 .067 .121
372.00 ----- 3874 10644 .081 .202
373.00 ----- 4556 12631 .097 .299
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: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Vol: Pipe
Name.... U.G. DET. #2
Page 4.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
COMPUTED VOLUMES FOR A PIPE
US Invert Elev.= 371.00 ft
DS Invert Elev.= 371.00 ft
Barrel Length = 190.00 ft
Computed Slope = .000000 ft/ft
Diameter = 3.0000 ft
# of Barrels = 1.00
Slice Width = .50 ft
Vertical Incr. _ .10 ft
Perpendicular Wetted Filled Perpendicular Total
Elevation DS Depth DS Area Length Length US Depth US Area Volume
(ft)
---------- (ft)
----------- (sq.ft)
--------- (ft)
---------- (ft)
---------- (ft)
---------- (sq.ft)
--------- (ac-ft)
---------
371.00 .00 .0000 190.00 .00 .00 .0000 .000
371.10 .10 .0723 190.00 .00 .10 .0723 .000
371.20 .20 .2024 190.00 .00 .20 .2024 .001
371.30 .30 .3679 190.00 .00 .30 .3679 .002
371.40 .40 .5603 190.00 .00 .40 .5603 .002
371.50 .50 .7744 190.00 .00 .50 .7744 .003
371.60 .60 1.0064 190.00 .00 .60 1.0064 .004
371.70 .70 1.2535 190.00 .00 .70 1.2535 .005
371.80 .80 1.5132 190.00 .00 .80 1.5132 .007
371.90 .90 1.7835 190.00 .00 .90 1.7835 .008
372.00 1.00 2.0626 190.00 .00 1.00 2.0626 .009
372.10 1.10 2.3487 190.00 .00 1.10 2.3487 .010
372.20 1.20 2.6404 190.00 .00 1.20 2.6404 .012
372.30 1.30 2.9360 190.00 .00 1.30 2.9360 .013
372.40 1.40 3.2345 190.00 .00 1.40 3.2345 .014
372.50 1.50 3.5343 190.00 .00 1.50 3.5343 .015
372.60 1.60 3.8341 190.00 .00 1.60 3.8341 .017
372.70 1.70 4.1325 190.00 .00 1.70 4.1325 .018
372.80 1.80 4.4282 190.00 .00 1.80 4.4282 .019
372.90 1.90 4.7199 190.00 .00 1.90 4.7199 .021
373.00 2.00 5.0060 190.00 .00 2.00 5.0060 .022
373.10 2.10 5.2851 190.00 .00 2.10 5.2851 .023
373.20 2.20 5.5554 190.00 .00 2.20 5.5554 .024
373.30 2.30 5.8151 190.00 .00 2.30 5.8151 .025
373.40 2.40 6.0622 190.00 .00 2.40 6.0622 .026
373.50 2.50 6.2942 190.00 .00 2.50 6.2942 .027
373.60 2.60 6.5083 190.00 .00 2.60 6.5083 .028
373.70 2.70 6.7007 190.00 .00 2.70 6.7007 .029
373.80 2.80 6.8662 190.00 .00 2.80 6.8662 .030
373.90 2.90 6.9963 190.00 .00 2.90 6.9963 .031
374.00 3.00 7.0686 190.00 190.00 3.00 7.0686 .031
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Vol: Pipe
Name.... U.G. DET. #3
Page 4.03
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
COMPUTED VOLUMES FOR A PIPE
US Invert Elev.
DS Invert Elev.
Barrel Length
Computed Slope
Diameter
# of Barrels
370.00 ft
370.00 ft
220.00 ft
.000000 ft/ft
3.0000 ft
2.00
Slice Width = .50 ft
Vertical Incr. _ .10 ft
Perpendicular Wetted Filled Perpendicular Total
Elevation DS Depth DS Area Length Length US Depth US Area Volume
(ft) (ft)
--------- (sq.ft)
---------- (ft)
---------- (ft)
--------- (ft)
----------- (sq.ft)
--------- (ac-ft)
---------
----------
370.00 -
.00 .0000 220.00 .00 .00 .0000 .000
370.10 .10 .0723 220.00 .00 .10 .0723 .001
370.20 .20 .2024 220.00 .00 .20 .2024 .002
370.30 .30 .3679 220.00 .00 .30 .3679 .004
370.40 .40 .5603 220.00 .00 .40 .5603 .006
370.50 .50 .7744 220.00 .00 .50 .7744 .008
370.60 .60 1.0064 220.00 .00 .60 1.0064 .010
370.70 .70 1.2535 220.00 .00 .70 1.2535 .013
370.80 .80 1.5132 220.00 .00 .80 1.5132 .015
370.90 .90 1.7835 220.00 .00 .90 1.7835 .018
371.00 1.00 2.0626 220.00 .00 1.00 2.0626 .021
371.10 1.10 2.3487 220.00 .00 1.10 2.3487 .024
371.20 1.20 2.6404 220.00 .00 1.20 2.6404 .027
371.30 1.30 2.9360 220.00 .00 1.30 2.9360 .030
371.40 1.40 3.2345 220.00 .00 1.40 3.2345 .033
371.50 1.50 3.5343 220.00 .00 1.50 3.5343 .036
371.60 1.60 3.8341 220.00 .00 1.60 3.8341 .039
371.70 1.70 4.1325 220.00 .00 1.70 4.1325 .042
371.80 1.80 4.4282 220.00 .00 1.80 4.4282 .045
371.90 1.90 4.7199 220.00 .00 1.90 4.7199 .048
372.00 2.00 5.0060 220.00 .00 2.00 5.0060 .051
372.10 2.10 5.2851 220.00 .00 2.10 5.2851 .053
372.20 2.20 5.5554 220.00 .00 2.20 5.5554 .056
372.30 2.30 5.8151 220.00 .00 2.30 5.8151 .059
3?_.40 2.40 6.0622 220.00 .00 2.40 6.0622 .061
372.50 2.50 6.2942 220.00 .00 2.50 6.2942 .064
372.60 2.60 6.5083 220.00 .00 2.60 6.5083 .066
372.70 2.70 6.7007 220.00 .00 2.70 6.7007 .068
372.80 2.80 6.8662 220.00 .00 2.80 6.8662 .069
372.90 2.90 6.9963 220.00 .00 2.90 6.9963 .071
373.00 3.00 7.0686 220.00 220.00 3.00 7.0686 .071
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Vol: Pipe
Name.... U.G. DET.#1
Page 4.04
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
COMPUTED VOLUMES FOR A PIPE
US Invert Elev.= 364.00 ft
DS Invert Elev.= 364.00 ft
Barrel Length = 110.00 ft
Computed Slope = .000000 ft/ft
Diameter = 3.0000 ft
# of Barrels = 1.00
Slice Width = .50 ft
Vertical Incr. _ .10 ft
Perpendicular Wetted Filled Perpendicular Total
Elevation DS Depth DS Area Length Length US Depth US Area Volume
(ft)
---------- (ft)
----------- (sq.ft)
--------- (ft)
---------- (ft)
---------- (ft)
---------- (sq.ft)
--------- (ac-ft)
---------
364.00 .00 .0000 110.00 .00 .00 .0000 .000
364.10 .10 .0723 110.00 .00 .10 .0723 .000
364.20 .20 .2024 110.00 .00 .20 .2024 .001
364.30 .30 .3679 110.00 .00 .30 .3679 .001
364.40 .40 .5603 110.00 .00 .40 .5603 .001
364.50 .50 .7744 110.00 .00 .50 .7744 .002
364.60 .60 1.0064 110.00 .00 .60 1.0064 .003
364.70 .70 1.2535 110.00 .00 .70 1.2535 .003
364.80 .80 1.5132 110.00 .00 .80 1.5132 .004
364.90 .90 1.7835 110.00 .00 .90 1.7835 .005
365.00 1.00 2.0626 110.00 .00 1.00 2.0626 .005
365.10 1.10 2.3487 110.00 .00 1.10 2.3487 .006
365.20 1.20 2.6404 110.00 .00 1.20 2.6404 .007
365.30 1.30 2.9360 110.00 .00 1.30 2.9360 .007
365.40 1.40 3.2345 110.00 .00 1.40 3.2345 .008
365.50 1.50 3.5343 110.00 .00 1.50 3.5343 .009
365.60 1.60 3.8341 110.00 .00 1.60 3.8341 .010
365.70 1.70 4.1325 110.00 .00 1.70 4.1325 .010
365.80 1.80 4.4282 110.00 .00 1.80 4.4282 .011
365.90 1.90 4.7199 110.00 .00 1.90 4.7199 .012
366.00 2.00 5.0060 110.00 .00 2.00 5.0060 .013
366.10 2.10 5.2851 110.00 .00 2.10 5.2851 .013
366.20 2.20 5.5554 110.00 .00 2.20 5.5554 .014
366.30 2.30 5.8151 110.00 .00 2.30 5.8151 .015
366.40 2.40 6.0622 110.00 .00 2.40 6.0622 .015
366.50 2.50 6.2942 110.00 .00 2.50 6.2942 .016
366.60 2.60 6.5083 110.00 .00 2.60 6.5083 .016
366.70 2.70 6.7007 110.00 .00 2.70 6.7007 .017
366.80 2.80 6.8662 110.00 .00 2.80 6.8662 .017
366.90 2.90 6.9963 110.00 .00 2.90 6.9963 .018
367.00 3.00 7.0686 110.00 110.00 3.00 7.0686 .018
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Vol: Elev-Area
Name.... WET POND
Paqe 4.05
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
Elevation Planimeter Area Al+A2+sgr(A1*A2) Volume Volume Sum
(ft) (sq.in) (sq.ft) (sq.ft) (ac-ft) (ac-ft)
362.00 ----- 3727 0 .000 .000
363.00 ----- 4628 12508 .096 .096
364.00 ----- 5576 15284 .117 .213
365.00 ----- 6569 18197 .139 .352
366.00 ----- 7603 21239 .163 .514
367.00 ----- 8676 24401 .187 .701
368.00 ----- 9788 27679 .212 .913
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: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet con. wet.
Page 5.01
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 369.00 ft
Increment = .05 ft
Max. Elev.= 373.00 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
Inlet Box RO ---> CO 371.700 373.000
Orifice-Circular 00 ---> CO 370.500 373.000
Culvert-Circular CO ---> TW 369.000 373.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet con. wet.
Page 5.02
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = RO
Structure Type = Inlet Box
---------------
-------------------
# of Openings = --
1
Invert Elev. = 371.70 ft
Orifice Area = 16.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 16.00 ft
Weir Coeff. = 3.100
K, Reverse = 1.000
Mannings n = .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 370.50 ft
Diameter = .0830 ft
Orifice Coeff. _ .600
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet con. wet.
Page 5.03
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
----------------- = Culvert-Circular
-------------------
No. Barrels = 1
Barrel Diameter = 2.0000 ft
Upstream Invert = 369.00 ft
Dnstream Invert = 368.80 ft
Horiz. Length = 52.00 ft
Barrel Length = 52.00 ft
Barrel Slope = .00385 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .2000
Kb = .012411
Kr = .2000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0045
Inlet Control M = 2.0000
Inlet Control c = .03170
Inlet Control Y = .6900
T1 ratio (HW/D) = 1.093
T2 ratio (HW/D) = 1.195
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 = 371.19 ft ---> Flow = 15.55 cfs
At T2 Elev = 371.39 ft ---> Flow = 17.77 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 40
Min. TW tolerance = .O1 ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #1
Page 5.04
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 364.00 ft
Increment = .05 ft
Max. Elev.= 367.00 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
Orifice-Circular 00 ---> CO 364.000 367.000
Weir-Rectangular WO ---> CO 366.400 367.000
Culvert-Circular CO ---> TW 364.000 367.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #1
Page 5.05
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 364.00 ft
Diameter = .1670 ft
Orifice Coeff. _ .600
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
WO
Weir-Rectangular
----------------
1
366.40 ft
3.00 ft
3.100000
Weir TW effects (Use adjustment equation)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #1
Page 5.06
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
----------------- = Culvert-Circular
-------------------
No. Barrels = 1
Barrel Diameter = 1.2500 ft
Upstream Invert = 364.00 ft
Dnstream Invert = 363.50 ft
Horiz. Length = 50.00 ft
Barrel Length = 50.00 ft
Barrel Slope = .01000 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .2000
Kb = .023225
Kr = .2000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equati on form = 1
Inlet Control K = .0045
Inlet Control M = 2.0000
Inlet Control c = .03170
Inlet Control Y = .6900
T1 ratio (HW/D) = 1.090
T2 ratio (HW/D) = 1.192
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 = 365.36 ft ---> Flow = 4.80 cfs
At T2 Elev = 365.49 ft ---> Flow = 5.49 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maximum Iterations= 40
Min. TW tolerance = .O1 ft
Max. TW tolerance = .01 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #2
Page 5.07
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 371.00 ft
Increment = .05 ft
Max. Elev.= 374.00 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
Orifice-Circular 00 ---> CO 371.000 374.000
Weir-Rectangular WO ---> CO 373.400 374.000
Culvert-Circular CO ---> TW 371.000 374.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #2
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 371.00 ft
Diameter = .0830 ft
Orifice Coeff. _ .600
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
weir TW effects (Use adjustment equation)
WO
Weir-Rectangular
----------------
1
373.40 ft
3.00 ft
3.100000
Page 5.08
S/N: DOYXYWH3NLBE
PondPack (10.00.015.00)
11:18 AM
Withers & Ravenel
7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #2
Page 5.09
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
------------------ = Culvert-Circular
------------------
No. Barrels = 1
Barrel Diameter = 1.5000 ft
Upstream Invert = 371.00 ft
Dnstream Invert = 370.50 ft
Horiz. Length = 32.00 ft
Barrel Length = 32.00 ft
Barrel Slope = .01563 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0150
Ke = .2000
Kb = .024249
Kr = .2000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0045
Inlet Control M = 2.0000
Inlet Control c = .03170
Inlet Control Y = .6900
T1 ratio (HW/D) = 1.088
T2 ratio (HW/D) = 1.189
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 = 372.63 ft ---> Flow = 7.58 cfs
At T2 Elev = 372.78 ft ---> Flow = 8.66 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maximum Iterations= 40
Min. TW tolerance = .O1 ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .01 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #3
Page 5.10
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 370.00 ft
Increment = .05 ft
Max. Elev.= 373.00 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
Orifice-Circular 00 ---> CO 370.000 373.000
Weir-Rectangular WO ---> CO 372.100 373.000
Culvert-Circular CO ---> TW 370.000 373.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #3
Page 5.11
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston_rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 370.00 ft
Diameter = .2500 ft
Orifice Coeff. _ .600
Structure ID
Structure Type
--------------
# of Openings
Crest Elev.
Weir Length
Weir Coeff.
wo
Weir-Rectangular
----------------
1
372.10 ft
3.00 ft
3.100000
Weir TW effects (Use adjustment equation)
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet UGD #3
Page 5.12
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
-
--- = Culvert-Circular
------------------
-
-------------
No. Barrels = 1
Barrel Diameter = 2.0000 ft
Upstream Invert = 370.00 ft
Dnstream Invert = 369.00 ft
Horiz. Length = 12.00 ft
Barrel Length = 12.04 ft
Barrel Slope = .08333 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .2000
Kb = .012411
Kr = .2000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0045
Inlet Control M = 2.0000
Inlet Control c = .03170
Inlet Control Y = .6900
T1 ratio (HW/D) = 1.054
T2 ratio (HW/D) = 1.156
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 = 372.11 ft ---> Flow = 15.55 cfs
At T2 Elev = 372.31 ft ---> Flow = 17.77 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 40
Min. TW tolerance = .Ol ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet wet pond
Page 5.13
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 362.00 ft
Increment = .05 ft
Max. Elev.= 368.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall El, ft E2, ft
Inlet Box RO ---> CO 366.500 368.000
Orifice-Circular 00 ---> CO 365.000 368.000
Culvert-Circular CO ---> TW 361.500 368.000
TW SETUP, DS Channel
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet wet pond
Page 5.14
File.... K:\06\06-1600\061601-Park at Langston\H-H\PPack\Langston rev071107.ppw
OUTLET STRUCTURE INPUT DATA
Structure ID = RO
Structure Type = Inlet Box
------------------
# of Openings ------------------
= 1
Invert Elev. = 366.50 ft
Orifice Area = 25.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 20.00 ft
Weir Coeff. = 3.100
K, Reverse = 1.000
Mannings n = .0000
Kev,Charged Riser = .000
Weir Submergence = No
Structure ID = 00
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 365.00 ft
Diameter = .1670 ft
Orifice Coeff. _ .600
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Type.... Outlet Input Data
Name.... Outlet wet pond
Page 5.15
OUTLET STRUCTURE INPUT DATA
Structure ID = CO
Structure Type
----------------- = Culvert-Circular
--------
-
----

No. Barrels --
--
= 1 --
Barrel Diameter = 2.5000 ft
Upstream Invert = 361.50 ft
Dnstream Invert = 361.00 ft
Horiz. Length = 50.00 ft
Barrel Length = 50.00 ft
Barrel Slope = .01000 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .2000
Kb = .009217
Kr = .2000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0045
Inlet Control M = 2.0000
Inlet Control c = .03170
Inlet Control Y = .6900
T1 ratio (HW/D) = 1.090
T2 ratio (HW/D) = 1.192
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At T1 Elev = 364.23 ft ---> Flow = 27.16 cfs
At T2 Elev = 364.48 ft ---> Flow = 31.05 cfs
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 40
Min. TW tolerance = .O1 ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .O1 ft
Min. Q tolerance = .00 cfs
Max. Q tolerance = .00 cfs
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

Appendix A
Index of Starting Page Numbers for ID Names
----- C -----
CON. WETLAND... 4.01
----- D -----
DA #1 TREATED... 2.01, 3.01
DA #lA TREATED... 2.04, 3.02
DA #2 TREATED... 2.06, 3.03
DA #2A TREATED... 2.08, 3.04
DA #3 TREATED... 2.10, 3.05
DA UNTREATED... 2.12, 3.06
----- O -----
Outlet con. wet.... 5.01
Outlet UGD #1... 5.04
Outlet UGD #2... 5.07
Outlet UGD #3... 5.10
Outlet wet pond... 5.13
----- R -----
RDU NOAA 14 Desi... 1.01
----- U -----
U.G. DET. #2... 4.02
U.G. DET. #3... 4.03
U.G. DET.#1... 4.04
----- w -----
WET POND... 4.05
A-1
S/N: DOYXYWH3NLBE Withers & Ravenel
PondPack (10.00.015.00) 11:18 AM 7/11/2007

NITROGEN
CALCULATIONS

Nitrogen Control Plan
Residential Subdivision with no known building footprints
Project Title: The Park at Langston
Part t. Riparian Buffers
Area includes riparian buffers?
If yes,
River Basin?
Basis for Exemption
Show buffers on site plan.
Part 11. Nitrogen Calculations (Method 1, Appendix C):
a. Subdivision Information
Number of lots
Total area of lots (excluding
RNV and open space)
Number of lots 1 acre
Average lot size
Impervious area per lot
b. Pre-development loading:
39
12.06 ac
3.23
13470 sf
4000 sf
Type of Land Cover
Permanently protected undisturbed open
space (forest, unmown meadow)
Permanently protected managed open space
(grass, landscaping, etc.)
Impervious Area
TOTAL
Pre-development Nitrogen Loading Rate (Ibs/ac/yr) _
c. Post-development loadino:
Residential
Type of Land Cover
Permanently protected undisturbed open
space (forest, unmown meadow)
Permanently protected managed open space
(grass, landscaping, etc.)
Right-of-Way (read TN export from Graph 1)
Lots (read TN export from Graph 2)
Amount of Right-of--Way
Percent of Right-of--Way
that is impervious area
Amount of Right-of-Way
2.67 ac
49.00%
that is impervious area 1.31 ac
Total estimated impervious area 4.89 ac
TN Export
Area TN export coeff from use
(acres) (Ibs/aciyr) {Ibs/yr)
17.59 0.8 10.55
1.87 1.2 2.244
0.34 21.2 7.208
19.80 20.01
1.01
TOTAL
TN Export
Area TN export coeff from use
(acres) (Ibs/aclyr) (Ibslyr)
4,05 0.6 2.43
1.02 1.2 1.22
2.67 8.6 22.96
12.06 4.3 51.86
19.80 78.47
Post-development Nitrogen Loading Rate (Ibs/ac/yr) = 3.96
Proposed BMP(s) Wet Pond and Stormwater Wetland
Nitrogen Load after BMPs = 3.34 Ibs/aGyr Estimated Buy Down = $0
Nitrogen Load offset by Payments = 0.00 Ibs/aclyr
Net change in on-site NLoad = 2.33 Ibs/ac/yr (Post BMP load less Pre-development N load)
Part III. Control of Peak Stormwater Flow (for 1 year, design storm) ~~~,,,,,,,,,,,,,,y~~
Calculated Pre-development Peak Flow 8.11 cfs ,~~„~N (`'ARO~~~~9~4
Calculated Post-development Peak Flow 20.85 cfs ~.••'•~"'•.~~
. ,~0.OFESSIpy.'f'
Proposed BMP(s) see note' ~'~ q •9
Post BMP Peak Flow 8.07 cfs ~~ ; a ~~ ~' , d1
ggg 1
"Note: Wet Pond, Stormwater Wetland, and 3 underground pipe detention systems ~ ~ ,~2~8421 ;~
I, the undersigned, certify to the best of my knowledge that the above information is correct (affix seal). 'S••b~;NG(IyEEQ:•••Q~
•b•r~••
Supply notes 8 details showing control of Nitrogen and peak stormwater nrnoff. ~q~ ~AQS~
1py>,urur~
[ ] No [X] Yes [ ]Exempt
[ ] 50 foot (X) 100 foot
[X) Neuse [ ]Cape Fear

Nitrogen Loading Calculations
Project Name: The Park at Langston
Project #: 2061601
TOTAL TRACT
Date: 7/12/2007
Computed by: C.H. Wadsworth
Total Area: 862,488 sgft. = 19.80 ac.
Right-of-Way Area: 116,305 sgft. = 2.67 ac. 49.00 % Impervious
Right-of-Way Impervious 56,990 sgft. = 1.31 ac.
Natural Open Space Area: 176,418 sgft. = 4.05 ac.
Managed Open Space Area: 44,431 sgft. = 1.02 ac.
Residential Lot Area: 525,334 sgft. = 12.06 ac.
Estimated Pre-Development TN Loading
Type of Land Cover Acres Ibs/aG rOe TN EXPORT ( Ibs/yr)
Permanently Protected Undisturbed Area 17.59 0.6 10.55
Permanently Protected Managed Area 1.87 1.2 2.24
Impervious 0.34 21.2 7.21
Totals 19.80 1.0 20.01
Estimated Post-Development TN Loading
Drainage Area 1: Wet Pond
Type of Land Cover Acres Oe TN EXPORT ( Ibs/yr)
Ibs/aG r
Permanently Protected Undisturbed Area 0.00 0.6 0.00
Permanently Protected Managed Area 0.49 1.2 0.59
Right-of-way 1.39 8.6 11.95
Lots 3.54 4.3 15.22
Totals 5.42 27.76
Estimated BMP Reduction for Riparian Buffer: 25
Estimated Drainage Area 1 Nitrogen Loading Reduction: 8.94 Ibs/yr
Drainage Area 2: Stomrwater Wetland

Type of Land Cover
Acres xpo oe .
TN EXPORT ( Ibs/yr)
Ibs/ac/ r
Permanently Protected Undisturbed Area 0.00 0.6 0.00
Permanently Protected Managed Area 0.36 1.2 0.43
Right-of-way 0.66 8.6 5.68
Lots 1.67 4.3 7.18
Totals 2.69 13.29
Estimated 8MP Reduction for wet fond: au ro
Estmated Drainage Area 2 Nitrogen Loading Reduction: 5.32 Ibslyr
Drainage Area 3: Remaining Area of Tract
Type of Land Cover Acres e TN EXPORT ( Ibs/yr)
Ibs/ac/ r
Permanently Protected Undisturbed Area 4.05 0.6 2.43
Permanently Protected Managed Area 0.17 1.2 0.20
Right-of-way 0.62 8.6 5.33
Lots 6.85 4.3 29.46
Totals 11.69 37.42
Estimated BMP Reduction: 0
Estimated Drainage Area 3 Nitrogen Loading Reduction: 0.00 Ibs/yr
Estimated Project Pre-BMP TN Export: 78.47 Ibs/yr
Estimated Project BMP TN Removal: 12.26 Ibalyr
Estimated Project TN Load Rate After BMPs: 3.34 Ibs/aGyr
Estimated Project Composite Nitrogen Loading Rate Reduction. 15.82

BMP
CALNLATIONS

Wet Pond #1
Proiect Name: Park at Langston Proiect #: 2061601
it / :Cary, NC Date: 12-Apr-07
Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85`Y Pollutant
Rvmnval FffiriPnrv in the Piw/mnnt
Impervious
Cover Permanent Pool Dep
3.0 4.0 5.0 6.0 th (feet)
7.0 8.0 9.0
10 0.59 0.49 0.43 0.35 0.31 0.29 0.26
20 0.97 0.79 0.70 0.59 0.51 0.46 0.44
30 1.34 1.08 0.97 0.83 0.70 0.64 0.62
40 1.73 1.43 1.25 1.05 0.90 0.82 0.77
50 2.06 1.73 1.50 1.30 1.09 1.00 0.92
60 2.40 2.03 1.71 1.51 1.29 1.18 1.10
70 2.88 2.40 2.07 1.79 1.54 1.35 1.26
80 3.36 2.78 2.38 2.10 1.86 1.60 1.42
90 3.74 3.10 2.66 2.34 2.11 1.83 1.67
Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 5, April 1999
STORMWATER BMP #1 -WET POND (85% TSS Removal 8~ 25% TN Removal)

Land Use Area
(ac) % IA Imp. Area
(ac)
O en S ace 0.49 0 0.0
Impervious 7.54 30 2.3
Totals 8.03 2.3
Total % Impervious Surface Area = 28.2
Normal Pool De th 3 4 5 6 7 8 9
SA/DA Ratio 1.32 1.08 1.04 0.84 0.65 0.61 0.53
Minimum Surface Area Re uired
Acres 0.106 0.086 0.084 0.068 0.052 0.049 0.042
Sq. Ft 4609.34 3760.49 3643.23 2943.65 2285.46 2123.38 1843.55
Surface Area of Permanem
Assumed depth =
SA/DA ratio =
Minimum pond surface are
SA =
Pool:
3
1.32
a (SA) _
0.106
4609
feet
From Table 1.1
JA * SA/DA ratio)/100
acres
sq. ft.
Normal pool elevation = 365.00 feet
Surface area provided = 0.151 acres
6578 sq. ft.
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where, Rv =Runoff coefficient, in./in.
I =Percent impervious
Rv = 0.30 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.203 acre-ft
8847 cu. ft.
Water quality pool elevation = 366.50 feet
Storage volume provided = 0.605 acre-ft
26354 cu. ft.

Project Name: Park at Langston
City/State: Cary, NC
STORMWATER BMP #1-WET POND (25% TN Removal)
Orifice Calculator

Variables
WQ Volume: 0.203108 Acre-ft
Head: 4.00 ft
Draw down time: 16.5 hrs
Orifice Area = 0.021874 sq. ft
8847.399 cf
2 ft
59400 s
3.149796 sq. in
Project #: 2061601
Date: 12-Apr-07
Constants
g = 32.2 ft/sz
Cd = 0.6
Orifice Diameter = 2.00261 in

Project Name: Park at Langston
iC ty/State: Cary, NC
Proiect #: 2061601
Date: 1 1-J u I-07
Table 1.1 Surface Area to Drainage Area Ratio for Permanent Pool Sizing for 85% Pollutant
Removal Efficiency in the Piedmont
Impervious
Cover Permanent Pool Dep
3.0 4.0 5.0 6.0 th (feet)
7.0 8.0 9.0
10 0.59 0.49 0.43 0.35 0.31 0.29 0.26
20 0.97 0.79 0.70 0.59 0.51 0.46 0.44
30 1.34 1.08 0.97 0.83 0.70 0.64 0.62
40 1.73 1.43 1.25 1.05 0.90 0.82 0.77
50 2.06 1.73 1.50 1.30 1.09 1.00 0.92
60 2.40 2.03 1.71 1.51 1.29 1.18 1.10
70 2.88 2.40 2.07 1.79 1.54 1.35 1.26
80 3.36 2.78 2.38 2.10 1.86 1.60 1.42
90 3.74 3.10 2.66 2.34 2.11 1.83 1.67
Source: NCDENR/DWQ Stormwater Best Management Practices, pg. 5, April 1999
STORMWATER BMP #2 -WETLAND (85% TSS Removal 8~ 40% TN Removal)

Land Use Area
(ac) % IA Imp. Area
(ac)
O en S ace 0.15 0 0.0
Impervious 2.37 35 0.8
Tota s 2.52 0.8
Total % Impervious Surface Area = 32.9
Normal Pool De th 3 4 5 6 7 8 9
SA/DA Ratio 1.45 1.18 1.05 0.89 0.76 0.69 0.66
Minimum Surface Area Re wired
Acres 0.037 0.030 0.027 0.023 0.019 0.017 0.017
Sq. Ft 1595.80 1297.59 1154.43 981.54 832.43 760.17 728.61
Surface Area of Permanent Pool:
Assumed depth = 3 feet
SA/DA ratio = 1.45 % From Table 1.1
Minimum pond surface area (SA) _ (DA * SA/DA ratio)/100
SA = 0.037 acres
1596 sq. ft.
Normal pool elevation = 369.00 feet
Surface area provided = 0.047 acres
2065 sq. ft.
1-Inch Runoff Volume Calculation
Using the runoff volume calculations in the "Simple Method" as described by Schueler (1987)
Rv = 0.05 + 0.009(1) where, Rv =Runoff coefficient, in./in.
I =Percent impervious
Rv = 0.35 in./in.
Total runoff volume from 1-inch precipitation:
Runoff volume, S = (Design rainfall) (Rv) (Drainage Area)
S = 0.073 acre-ft
3167 cu. ft.
Water quality pool elevation= 371.50 feet
Storage volume provided = 0.091 acre-ft
3960 cu. ft.

Project Name: Park at Langston
City/State: Cary, NC
STORMWATER BMP #2- WETLAND (40% TN Removal)
Orifice Calculator

Variables
WQ Volume: 0.072713 Acre-ft 3167.357 cf
Head: 1.20 ft 0.6 ft
Draw down time: 43 hrs 154800 s
Orifice Area = 0.005486 sq. ft 0.789985 sq. in
Project #: 2061601
Date: 11-) u I-07
Constants
g = 3 2.2 ft/s2
Cd = 0.6
Orifice Diameter = 1.00 in