20090735 Ver 1_Stormwater Info_20090629

THE JOHN R. McADAMS COMPANY, INC.
..09--0 7 35
CORBINTON COMMONS
HILLSBOROUGH, NORTH CAROLINA
IN
JUN 2 ?
?009
FINAL DESIGN CALCULATIONS VVET(,g1DSg1? S 'W R9?t4N
WATER QUALITY POND #1 Ct1
WATER QUALITY POND #2
EYC-06010
November 2006
Research Triangle Park, NC
Post Office Box 14005
Research Triangle Park.
North Carolina 27709
2905 Meridian Parkway
Durham, North Carolina 27713
800-733-5646
919-361-5000
919-361-2269 Fax
Charlotte, NC
5311 Seventy-Seven Center Drive,
Suite 66
Charlotte, North Carolina 28217
800-733-5646
704-527-0800
704-527-2003 Fax
www.john rmcadams.corn
Designed by:
Beth Ihnatolya, El
Associate Project Engineer
Stormwater and Environmental Department
Checked by:
Jeremy Finch, PE
Stormwater Project Manager
Stormwater and Environmental Department
Comprehensive Land Development Design Services
ll,: help orr cliew,s _+ucceed.
::; . ARCADIS
Infrastructure, environment, facilities
Ms. Margaret A. Hauth, AICP
Planning Director
Town of Hillsborough
PO Box 429
Hillsborough, NC 27278
Subject:
Hillsborough, North Carolina
Corbinton Commons Stormwater Review
Dear Ms. Hauth:
We have completed our review of the plans and calculations submitted by The John
R. McAdams Company, Inc., for the Corbinton Commons development. The
calculations show the development generally conforms to the Town's Zoning
Ordinance Article 5.19.
Please do not hesitate to call me if you have any questions concerning this review.
Sincerely,
ARCADIS G&M of North Carolina, Inc.
Linda Pass, PE
Copies:
Mr. Jonathan P. Eakins; PE, The John R. McAdams Companv, Inc.
Mr. Jeremy V. Finch, PE, The John R. McAdams Company, Inc.
ARCADIS G&M
of North Carolina, Inc.
One Centerview Drive
Suite 208
Greensboro
North Carolina 27407
Tel [phone]
Fax [phone]
Date:
4 December 2006
Contact:
Linda Pass
Phone:
336 292 2271
Email:
lpass @arcadis-us.com
Imagine the result
CORBINTON COMMONS
Final Design-Water Quality Ponds #I and #2
Proiect Description and Summary
Located off from US Highway 70 and just north of St. Mary's Road in Hillsborough, North
Carolina is the proposed development currently known as Corbinton Commons. The proposed
site is approximately 40-acres, and is comprised of commercial buildings, single-family lots,
townhome lots, a clubhouse/amenity area, along with the associated utility, parking, and roadway
infrastructure. In the post-development condition, the site will be approximately 32%
impervious. This report contains the final design calculations for the proposed water quality
pond #1 and the proposed water quality pond #2.
The proposed development is located within the Neuse River Basin and drains to an unnamed
tributary to the Eno River. Chapter 16, Section 5.19 of the Town of Hillsborough Zoning
Ordinance states the following water quality requirements:
a) The first half inch (112') of rain shall be handled on-site with either structural or
non-structural devices reviewed by the Town Engineer.
b) Stormwater control structures shall be designed to accommodate a 10 year storm
event.
c) The rate of run-off from the developed site shall not be greater than that of the
undeveloped site, based on a 10 year storm event.
d) Water flows shall not be diverted onto neighboring properties beyond
preconstruction levels.
,0 To address these stormwater requirements, water quality ponds with preformed scour hole/level
spreader outlets that will provide sheet flow of the first ''/z" runoff volume into the stream buffer
are proposed for construction. This report contains the design calculations for water quality
pond #1 and water quality pond #2, which satisfactorily meet the water quality and water
quantity requirements.
Calculation Methodology
? Rainfall data for the Hillsborough, NC region is derived from USWB Technical Paper
No. 40 and NOAA Hydro-35. This data was used to generate a depth-duration-frequency
(DDF) table describing rainfall depth versus time for varying return periods. These
rainfall depths were then input into the meteorological model within HEC-HMS for peak
flow rate calculations. Please reference the rainfall data section within this report for
additional information.
? Using maps contained within the Orange County Soil Survey, the on- and off-site soils
were determined to be from hydrologic soil group (HSG) `B', `C', and `D' soils. Since
the method chosen to compute both pre- and post-development peak flow rates and
runoff volumes is dependent upon the soil type, all hydrologic calculations are based
upon the relative percentage of each HSG within each subbasin.
? A composite SCS Curve Number was calculated for both the pre- and post-development
condition using SCS curve numbers and land cover conditions. On-site land cover
conditions for the pre-development condition were taken from a field survey performed
by The John R. McAdams Company, Inc. Off-site land cover conditions for the pre-
development and post-development conditions were taken from both aerial photography
and Town of Hillsborough GIS information. On-site land cover conditions for the post-
development condition were taken from the proposed development plan.
? The time of concentration was calculated using SCS TR-55 (Segmental Approach, 1986).
The Tc flow path was divided into three segments: overland flow, concentrated flow, and
channel flow. The travel time was then computed for each segment, from which the
overall time of concentration was determined by taking the sum of each segmental time.
The post-development times of concentration to each stormwater facility are assumed to
be 5 minutes in the post-development condition.
? All on-site topo was taken from a topographic survey performed by The John R.
McAdams Company, Inc. All off-site topo was taken from lidar information. The
drainage maps for both the pre- and post-development condition have been included in
this report.
? HEC-HMS Version 2.2.2, by the U.S. Army Corps of Engineers, is used to generate post-
development peak flow rates. The proposed water quality pond #1 and the proposed
water quality pond #2 routing calculations were also performed within HEC-HMS.
? Pondpack Version 8.0, by Haestad Methods, is used to generate the stage-discharge
rating curves for the proposed water quality pond #1 and the proposed water quality pond
#2. These rating curves were then input into HEC-HMS for routing calculations.
? The stage-discharge rating curve, stage-storage rating curve, and stage-storage function
for the proposed water quality pond #1 and the proposed water quality pond #2 were all
generated outside of HEC-HMS and then input into HEC-HMS.
• ? Anti-flotation calculations were performed on the riser-barrel outlet structures in order to
ensure enough concrete was provided to guard against flotation with a minimum 15%
factor of safety. Riser sections for the manhole are to be securely fastened together to
prevent separation due to buoyant forces.
? A velocity dissipator is provided at the end of the principal spillway outlet for the
proposed water quality pond #1 and the proposed water quality pond #2 to prevent
erosion and scour in the downstream areas. The dissipators will be constructed using
riprap, underlain with a woven geotextile filter fabric. The filter fabric is used to
minimize the loss of soil particles beneath the riprap apron. The dissipators are sized for
the 10-year storm event using the NYDOT method. It is a permanent feature of the outlet.
? For 100-year storm routing calculations, a "worst case condition" was modeled in order
to insure the proposed water quality pond #1 and the proposed water quality pond #2
would safely pass the 100-year storm event. The assumption used in this scenario are as
follows:
1. The starting water surface elevation in each facility, just prior to the 100-year
storm event, is at the top of riser elevation. This scenario could occur as a result of
a clogged orifice or a rainfall event that lingers for several days. This could also
occur as a result of several rainfall events in a series, before the orifice has an
opportunity to draw down the storage pool.
2. An attempt was made to achieve a minimum of approximately 0.5-ft of freeboard
between the peak elevation during the "worst case" scenario and the top of the
dam for the ponds.
•
? The downstream tailwater elevations for the proposed ponds were assumed to be a free
• outfall condition during the 10-year storm event (a conservative assumption).
Discussion of Results
There are two (2) water quality ponds to be constructed as part of the proposed development.
These facilities will function as stormwater devices by providing detention so that the post-
development peak flow rates are no greater than pre-development peak flow rates in the 10-year
storm. Please refer to the Summary of Results table for additional information.
Conclusion
If the Corbinton Commons development is built as proposed within this report, then the
requirements set forth in Chapter 16, Section 5.19 of the Town of Hillsborough Zoning
Ordinance will be met with the proposed water quality ponds. However, modifications to the
proposed development may require that this analysis be revised. Some modifications that would
require this analysis to be revised include:
1. The proposed site impervious surface exceeds the amount accounted for in this report.
2. The post-development watershed breaks change significantly from those used to prepare
this report.
The above modifications may result in the assumptions within this report becoming invalid. The
computations within this report will need to be revisited if any of the above conditions become
• apparent as development of the proposed site moves forward.
0
•
CORBINTON COMMONS
EYC-06010
SUMMARY OF RESULTS
_> RELEASE RATE MANAGEMENT RESULTS
B. IHNATOLYA, El
11/21/2006
Return Period Pre-DevelopmenC Post-Development l % Increase
[cfs] [ refs]
POA #1 _, ?..
I0-Year 1 64") 0"'o -l I
SUBBASIN #2
.... _........ ..._.__
10-Year 1 _ A 0.2 1 v,
.. SUBBASIN #3 -- _ .. - __ ._ .._? ... _.._ ?._..
10-Year " 1
_ ...... ,.
. _..._ _ ?. _
SUBBASIN #4
10-Year 0.4 0.7 98.3%
**NOTE** It is recognized that there is an increase in the peak flowrates from pre- to post-development in the
l0-year storm for subbasins #2, #3, and #4. However, the actual increase in the peak flowrates from
pre- to post-development in the 10-year storm for subbasins #2 and #4 are both less than 1 cfs, which
is assumed to be a neglible amount. However, the increase in the peak flowrate from pre- to
post-development in the 10-year storm for subbasin #3 is 5.6 cfs. While it is recognized that this
is a sizable increase, it was also assumed neglible b/c the hydrograph for subbasin #3 combines with
the hydrograph for the overall watershed approx. 50 downstream from where subbasin #3 exits the
property line. Since the flow from subbasin #3 enters the creek prior to encountering the downstream
residential areas, it was assumed that while there is an increase proposed, the 10-year peak flowrate
in the main creek would be at or below pre-development levels as it enters the downstream residential
areas.
_> ROUTING RESULTS
u
•
WATER QUALITY POND #1
Return Period Inflow ; Outflow
[cfs] 1 [cfs] Max. WSE
[ft]
10-Year 36.2 14.6 523.7
100-Year 53.5 16.1 525.0
100-Year (Siphon Clogged) 53.5 15.8 525.0
Dessip Drains a Area = 6.48 acres
Desi nn Imp rviousArea = I 4.14 aacres
Top of Dam
Required Surface Area /Drainage Area Ratio - 526 00
2.56 ft
_ Surface Area at NWSE = 9449 sf?
Required Surface Area at NWSE = 7234 sf
Siphon Diameter = 1.5 inches
Total Number of Si hops = 1

Riser Len th = 4 ft
Riser Width =

Riser Crest = 4

522.30 ft
...........
....?
ft
_
Barrel Diameter)
# of Barrels 1

Invert In - 15 ;
1

516.50 inches

....
feet
Invert Out 516.00 feet
Len t_th 63 feet._.._..m._..__.___
Slope = 0.0079 ft/ft
CORBINTON COMMONS SUMMARY OF RESULTS B. IHNATOLYA, El
EYC-06010 11/21/2006
•
•
WATER QUALITY POND #2
Return Period Inflow Outflow Max. WSE
[cfs] [cfs] [ft]
10-Year
--? 72.9 3.3 528.1
100-Year 114.5 40.2 528.8
100-Year (Siphon Clogged) 114.5 49.4 529.7
Design Drainage Area =
.,. .. __? 15.14 acres
Design Impervious Area = 7.27 acres

._........_,..530µ00 ft
Re uir.ed Surface Area / Drainage Area Ratio -
_ __.e.
Surface Area at NWSE =
Required Surface Area at NWSE -
Siphon Diameter= 1.81
_..
25199
11969
?2

sf
'sf
inches
......... Total Number of Siphons
.
.... _?..._.. .__.,._ _?_....
1
........ __?__

l ?. ........
Riser Length = 5 ft
Riser Width =
- 5 ft
Riser Crest = 528.00 ft
Barrel Diameter= 24 inches
# of Barrels = 1
Invert In
__ ._.......
Invert ut
Length 518.50 j

518.00
82 ? ; feet
?...................... ..._.._ ......
eet_
feet
Slope - 0.0061 f?_-
•
•
•
0
1 RAINFALL DATA
2 PRE-DEVELOPMENT SOILS DATA

3 POST-DEVELOPMENT SOILS
DATA
4 US GEOLOGICAL SURVEY MAP

5 PRE-DEVELOPMENT
HYDROLOGIC CALCULATIONS

6 POST-DEVELOPMENT
HYDROLOGIC CALCULATIONS

7 WATER QUALITY POND #7 FINAL
DESIGN CALCULATIONS

8 WATER QUALITY POND #2 FINAL
DESIGN CALCULATIONS
r?
RAINFALL DATA
C,
r?
CORBINTON COMMONS
EYC-06010
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PRE-DEVELOPMENT S'OILS DATA
0
0
CORBINTON COMMONS
EYC-06010
. .-
BONIN-
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Post-Subbasin-IA
0 ==> Watershed soils - Subbasin-IA
Symbol Name Soil Classification
Ch Chewacla C
EnB Enon C
GeC Georgeville B
GeB Georgeville B
GhC Georgeville-Urban B
HrB Herndon B
IrB Iredell D
IuB Iredell-Urban D
TaD Tatum B
TaE Tatum B
Ur Urban D
WxD White Store C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 76%
%HSGC= 10%
%HSGD= 14%
=> Conclusion
rVatershed soils are from 'HSG B ; 'HSGC; and 'HSG D'soils. The percentage of each HSG within the subbasin
•
was calculated. These percentages were then used in the computation of the composite curve numbers.
B. IHNATOLYA, El
11/21/2006
Cover Condition SCS CN - HSG B SCS CN - HSG C SCS CN - HSG D
Impervious 98 98 98
_Open 61 74 80
Wooded 55 70 ? 77
Commercial 92 94 95
Roads including Right-of-Way
rvµ µ 89 92 93
Residentia1425 acre lots
......... ..... 75
.. _____?.
_
_.
__
__
_
.
_ 83 87

Residential-0.5 acre lots .
.
.
.
..
..
.
_.
70
80
85
Residential-1.0 acre lots 68 79 84
Residential-2.0 acre lots 65 77 82
Cover Condition Composite SCS CN
Impervious 98
Open 65
Wooded 60
Commercial 93
Roads including Right-of-Way 90
Residential-0.25 acre lots 77 m mMM
Residential-0.5 acre lots 73
Residential-1.0 acre lots 71
Residential-2.0 acre lots 69
C7
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Pre-Subbasin-111
• => Watershed soils -Subbasin-1B
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
% HSG C = 0%
_> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded
55
Roads including Right-of-Way 89
--...__ ............ ....._.,..................... . .... ............._........_.................._.......,_.._
Residential-0.5 acre lots 70
Residential-1.0 acre lots
68
Residential-2.0 acre lots 65
•
B. IHNATOLYA, El
11/13/2006
0
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Pre-Subbasin-1C
• => Watershed soils - Subbasin-1 C
Symbol Name Soil Classification
GeC -Georgeville B
GeB Georgeville B
Ch Chewacla C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B= 92%
%HSGC= 8%
==> Conclusion
Watershed soils are from 'HSG B' and 'HSG C'soils. The percentage of each HSG within the subbasin
was calculated. These percentages were then used in the computation of the composite curve numbers.
Cover Condition SCS CN - HSG B SCS CN - HSG C
Impervious 98 98
Open 61
____._._.....,.....__._.............. _.._......_.._............................. ..______
. 74
_
..__e...... ._...... .-........
Wooded 55 ....____- _...__..____.a...___
70
Cover Condition Composite SCS CN
Impervious 98
•
Open
.-? .. 62
Wooded 55 ?__.._.._._._.._._....?._.__
B. IHNATOLYA, El
11/13/2006
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Pre-Subbasin-11)
0 _> Watershed soils - Subbasin-ID
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
Ch Chewacla C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 98%
%HSGC= 2%
=> Conclusion
Watershed soils are from 'HSG B' and 'HSG C'soils. The percentage of each HSG within the subbasin
was calculated. These percentages were then used in the computation of the composite curve numbers.
Cover Condition
_ SCS CN - HSG B SCS CN - HSG C
Impervious
.?"..____... _ 98
_.__ _._.?..._.._._ 98
Open
_.__. ._... _....-_..___..__ _?.._ _._..?_..._?..._..?_...__. 61 _?. __?.
.._.. _................ ...
?
.
....
.
.
.
? ._._ - 74

Wooded _
m
...
.
...
.
.
?..............._._........ _ ?___._._.
55 ......._.____. _._........... ______.............. .__..._. _ --
70

Cover Condition Composite SCS CN
• _ Impervious 98
Open
? 61
Wooded ? 55

CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Pre-Subbasin-2
• => Watershed soils - Subbasin 2
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
%HSGC= 0%
==> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded
55
Roads including Right-of-Way
..____,.....__......... _._._.........
.. -1--
.
_
_
. 89
.
.1
.....
.
...._....._
.
Residential-0.5 acre lots ................ __..... ..... ......... .............
70
Residential-1.0 acre lots 68
•
0
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Pre-Subbasin-3
• _> Watershed soils - Subbasin 3
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
%HSGC= 0%
_> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded
55

B. IHNATOLYA, El
11/13/2006
?J
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Pre-Subbasin-4
• => Watershed soils - Subbasin 4
Symbol Name Soil Classification
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
% HSG C = 0%
==> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
......_....... ._.e__.m.... _..._.__ew
Open 61
Wooded 55
•
B. IHNATOLYA, El
11/13/2006
•
•
POST-DE VEL OPMENT SOILS DA TA
U
0
CORBINTON COMMONS
EYC-06010

4083 0009 0 o0o l 000e 000f 0009 000S
y a
alm 1 0 Y. X11 V.
i
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Pre-Subbasin-1A
• => Watershed soils - Subbasin-JA
Symbol Name Soil Classification
_Ch Chewacla C

B

GeB
GhC
Georgeville
Georgeville-Urban _
B
B
HrB Herndon B
IrB m Iredell D
IuB Iredell-Urban D
TaD Tatum B
TaE Tatum B
Ur ? Urban D
WxD White Store C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 76%
% HSG C = 10%
% HSG D = 14%
> Conclusion
• Natershed soils are from 'HSG B, 'HSG C, and 'HSG D'soils. The percentage of each HSG within the Subbasin
was calculated. These percentages were then used in the computation of the composite curve numbers.
B. IHNATOLYA, El
11/21/2006
Cover Condition SCS CN - HSG B SCS CN - HSG C SCS CN - HSG D
Impervious
..?..,..?...? 98 98 98
Open 61 74
80.?...?._,?..._..
..? 80
Wooded 55 70 77
Commercial 92 94 95
Roads including Right-of-Way 89 92 93
Residential-0.25 acre lots 75 83 87
Residential-0.5 acre lots 70 80 85
Residential-1.0 acre lots
__._... 68
.... ......... ............ _....._.___.__...... _..... __......
_
__
...... 79
__
. 84

Residential-2.0 acre lots . .
.
..._
.
65 . ...
.....__.._..__..__................ ...._,_._.. ___.._...........__._
77 ________.._._...e__.___._.___
82
Cover Condition Composite SCS CN
Impervious 98
Open 65
Wooded 60
Commercial 93
Roads including Right-of-Way 90
Residential-0.25 acre lots 77
Residential-0.5 acre lots 73
Residential-1.0 acre lots 71
Residential-2.0 acre lots 69
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-1B
• -> Watershed soils - Subbasin-1B
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
% HSG C = 0%
-> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded
55
Roads including Right-of-Way 89
... ......................... ..._.,._._..._...._.. ...........
......._............._,.._......._....._..
Residential-0.5 acre lots 70
Residential-1.0 acre lots 68
Residential-2.0 acre lots 65
•

CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-IC-To WQ Pond #1
0 => Watershed soils - Subbasin-I C-To WQ Pond #1
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
%HSGC= 0%
==> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
_.._......... ........ ..._.... _..... .............. .__..??.__....__........ ............. ..... ?....? ............
_._... - ----
Wooded 55
•
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-lC-Bypass WQ Pond #1
• _> Watershed soils - Subbasin-I C-Bypass WQ Pond #1
Symbol Name Soil Classification
GeC _ Georgeville B
GeB Georgeville B
Ch Chewacla C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 82%
%HSGC= 18%
==> Conclusion
Watershed soils are from 'HSG B' and 'HSG C'soils. The percentage of each HSG within the subbasin
was calculated. These percentages were then used in the computation of the composite curve numbers.
Cover Condition SCS CN - HSG B SCS CN - HSG C
Impervious
..... 98 98
Open
........ ..... ._ .. 61
........ _ .
.
.
.. 74

Wooded ..
...
. _............. .
.
55 .._.-.... __......___._.?_
70

Cover Condition Composite SCS CN
• Impervious 98
Open 63
Wooded 58
0
CORBINTON COMMONS WATERSHED SOIL
EYC-06010 INFORMATION
Post-Subbasin-lD-To WQ Pond #2
• _> Watershed soils - Subbasin-ID-To Pond
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
% HSG C = 0%
=> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded 55
r?
B. IHNATOLYA, El
11/13/2006
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-lD-Bypass WQ Pond #2
• => Watershed soils - Subbasin-ID-Bypass
Symbol Name Soil Classification
GeC Georgeville B
G_eB _ Georgeville B
Ch Chewacla C
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 92%
%HSGC= 8%
=> Conclusion
Watershed soils are from 'HSG B' and 'HSG C'soils. The percentage of each HSG within the subbasin
was calculated. These percentages were then used in the computation of the composite curve numbers.
Cover Condition SCS CN - HSG B SCS CN - HSG C
Impervious 98
? 98
Open
_..__._....... __................ ___.?._...._____...?.?........?_? 61
_.._._._
...
.
.
. 74
Wooded .
.
..
.
... .-...._...__..____.._.............. ._.......
55 ..._......_.._._.___._-?.....---........__ ............
70

Cover Condition Composite SCS CN
?? Impervious 98
• Open 62
Wooded 56
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-2
• -> Watershed soils - Subbasin 2
Symbol Name Soil Classification
GeC Georgeville B
GeB v Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
%HSGC= 0%
__> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
.?......_ ?,.. Open - 61
Wooded
55
Roads including Right-of-Way
_......____....__._..__.........?-...___ __._w_ _. __.
.. 89
_
._._
Residential-0.5 acre lots ......... ...... .?....._.?._._-._.__ ? ._.b......_
70
Residential-1.0 acre lots 68
0
0
CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-3
• _> Watershed soils - Subbasin 3
Symbol Name Soil Classification
GeC Georgeville B
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
%HSGC= 0%
_> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded
55
0

CORBINTON COMMONS WATERSHED SOIL B. IHNATOLYA, El
EYC-06010 INFORMATION 11/13/2006
Post-Subbasin-4
• _> Subbasin 4
Symbol Name Soil Classification
GeB Georgeville B
References:
1) SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
% HSG B = 100%
% HSG C = 0%
_> Conclusion
Watershed soils are from 'HSG B'soils.
Cover Condition SCS CN - HSG B
Impervious 98
Open 61
Wooded 55
•

US GEOLOGICAL SURVEYDATA

•
CORBINTON COMMONS
EYC-06010
Copyright (C) 1998, Maptech, Inc.
•
PRE-DEVELOPMENT HYDROLOGIC
CALCULATIONS
•
is
CORBINTON COMMONS
EYC-06010
0 0 0
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, EI
EYC-06010 Pre-Development 1 1 /20/2006
1. SCS CURVE NITMBERS
Note:
The studied watershed contains 76% HSG "B" soils, 19% HSG "C" soils, and 5% HSG "D" soils.
SCS curve numbers were chosen accordingly.
Cover Condition
F-C SCS CN
Comments
Impervious 98
O en 65 Assume good condition
Wooded
_...., - - 60 Assume good condition
Commercial 93
Roads includm
Right of Way l 90
. .
Residential-0.25 acre lots 77 i -
w Residential-0.5 acre lots ? ? 73
Residential-1.0 acre lots
_-??
-??-- ?
-- 71
Residential-2.0 acre lots 69
•
•
II. PRE-DEVELOPMENT
_> Subbasin IA
A. Watershed Breakdown
Contributing Area SCS CN ! Area jacresj Comments
On-site Oven 65
0 0.00 Assume good condition
.?
On-site Wooded 6 0.00 Assume
&ood condition
On-site [mpervwus 98 0 00
- ..
On-Site Commercial 93 i 0.66
1
Offer 65 73.62 Assume food condition
Off-site Wooded 60 101.22 Assume good condition
Off site Im vious 98 7.45
Off-Site Commercial 93 46.72
Roads including Right-of-Way 90 i 22.89
Residential-0.25 acre lots 77 9.46
Residential-0.5 acre lots 73 ? 58
90
_._... - .
Residentiai-1.0 acre lots
.._......... 71 42.53
Residential-2.0 acre lots 69 17.67
._..
". _
Off--Site Pond 100 _
1.12
Total area = 381.58 acres
0.5962 sq.mi.
Composite SCS CN = 72
B. Time of Concentration Information
Time of'concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 0.4 ft
Slope = 0.0040 ft/ft
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 25.61 minutes
Segment 3: Channel Flow
Length = 869.8 ft
Height = 26 ft
Slope = 0.0299 ft/ft
Manning's n = 0.045 channel
Flow Area = 6.00 sf (3'x2' channel)
Wetted Perimeter = 7.00 ft (3'x2' channel)
Channel Velocity = 5.17 ft/sec
Segment Time = 2.,41 minutes
Segment 2: Concentrated Flow
Length = 208.1 ft
Height = 0.8 ft
Slope = 0.0038 ft/ft
Paved ? = No
Velocity = 1.00 ft/sec
Segment Time = 3.47 minutes
Segment 4. 3011 RCP
Length = 149.3 ft
Height = 2 ft
Slope = 0.0134 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 9.7{) ft/sec
Segment Time = 0.26 minutes
1 OF 2
r?
rI
CORBINTON COMMONS
EYC-06010
Segment 5. Channel Flow
HYDROLOGIC CALCULATIONS
Pre-Development
Length = 741.8 ft
Height = 21.9 ft
Slope = 0.0295 ft/ft
Manning's n = 0.045 channel
Flow Area = 6.00 sf (3'x2' channel)
Wetted Perimeter = 7.00 ft (3'x2' channel)
Channel Velocity = 5.13 ft/sec
Segment Time = 2.41 minutes
Segment 7. Channel Flow
Length = 575.6 ft
Height = 12.2 ft
Slope = 0.0212 ft/ft
Manning's n = 0.045 channel
Flow Area = 12.00 sf (4'x3' channel)
Wetted Perimeter = 10.00 ft (4'x3' channel)
Channel Velocity = 5.44 ft/sec
Segment Time = 1.76 minutes
Segment 9. Channel Flow
Length = 2584.9 ft
Height = 35.3 ft
Slope = 0.0137 ft/ft
Manning's n = 0.045 channel
Flow Area = 16.00 sf (4'x4' channel)
Wetted Perimeter = 12.00 ft (4'x4' channel)
Channel Velocity = 4.69 ft/sec
Segment Time = 9.19 minutes
Segment 6. 30" RCP
B. IHNATOLYA, El
11/20/2006
Length = 65.6 ft
Height = 0.1 ft
Slope = 0.0015 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 3.' ' ft/sec
Segment Time = 0.33 minutes
Segment 8: 30" RCP
Length = 55.4 ft
Height = 1.8 ft
Slope = 0.0325 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 15.10 ft/sec
Segment Time = 0.06 minutes
Segment 10: 30" RCP
Length = 126.3 ft
Height = 8.4 ft
Slope = 0.0665 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 21.61 ft/sec
Segment Time = 0.10 minutes
Segment 11: Channel Flow
Length = 98.4 ft
Height = 2.35 ft
Slope = 0.0239 ft/ft
Manning's n = 0.045 channel
Flow Area = 85.00 sf (I Tx5' channel)
Wetted Perimeter = 27.00 ft (I TxT channel)
Channel Velocity = 10.99 ft/sec
Segment Time = 0.15 minutes
Time of Concentration = 46.15 minutes
SCS Lag Time = 27.69 minutes (SCS Lag = 0.6* Tc)
= 0.4615 hours
Time Increment = 8.03 minutes (= 0.29*SCS Lag)

2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/13/2006
0 1. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is'HSG B'.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
Impervious 98

Wooded 61
55 _ Assume good condition
Assume good condition
Roads includin_Right-of-Wad 89
Residential-0.5 acre lots
Residential-1.0 acre lots
_......... ___ __
Residential-2.0 acre lots 68

65 -

-
•
11. PRE-DEVELOPMENT
-Subbasin IB
A. Watershed Breakdown
Contributing Area SCS CN Area jacres) Comments
On site Open 61 0.00 _Assume g2od condition
On-site Wooded
On-site Impervious 55
98 0.00
0.00 Assume good condition
-
Off-site en
_.._._____.__........._?.__ ..........

Off-site Wooded 61
...... .._......-..m._.-._....

55 2.76
..---------- _._

2.96 Assume good condition
._.__.._.........
_..
Assume good condition
Off-site Impervious 98 0.20
Roads including Right-of-Way

Residential 0 5 acre lots
Residential-1.0 acre lots 89

70
68 1.14
_.
2.46
7.10
_ __ _.....__. ? .... ...............

-
Residential-10 acre lots 65 3.60
Total area = 20.22 acres
0.0316 sq.mi.
Composite SCS CN = 66
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 6.2 ft
Slope = 0.0620 ft/ft
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 8.56 minutes
Segment 3: Channel Flow
Length = 1302.4 ft
Height = 79.5 ft
Slope = 0.0610 ft/ft
Manning's n = 0.045 channel
Flow Area = 2.00 sf (2'x1' channel)
Wetted Perimeter = 4.00 ft (2'x F channel)
Channel Velocity = 5.15 ft/sec
Segment Time = 4.21 minutes
•
Segment 2: Concentrated Flow
Length = 348.8 ft
Height = 18.3 ft
Slope = 0.0525 ft/ft
Paved ? = No
Velocity = 3.70 ft/sec
Segment Time = 1.57 minutes
1 OF 2
•
•
C7
CORBINTON COMMONS
EYC-06010
HYDROLOGIC CALCULATIONS
Pre-Development
B. IHNATOLYA, El
11/13/2006
Time of Concentration = 14.34 minutes
SCS Lag Time = 8.61 minutes (SCS Lag = 0.6* Tc)
= 0.1434 hours
Time Increment = 2.50 minutes = 0.29*SCS La
2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/13/2006
• 1. SCS CURVE NUMBERS
Note:
The studied watershed contains 92% HSG "B" soils and 8% HSG "C" soils.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 56 Assume good condition
H. PRE-DEVELOPMENT
_> Subbasin I C
A. Watershed Breakdown
Contributing Area SCS CN Area lacresl Comments
On-site en 62 0.00 Assume good condition
On-site Wooded
_...__ ..
On-site Impervious 56
98 8.78
0.00 Assume good condition
_.---- . __.....
-
Off, site en E

Off-site Wooded 62

56 0.13

1.09 Assume good condition
__._._._....-.__._.... .......
_..
Assume good condition
Off-site Impervious [ 98 0.16
Total area = 10.16 acres
0.0159 sq.mi.
Composite SCS CN = 57
• B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 2.6 ft
Slope = 0.0260 ft/ft
Manning's n = 0.40 woods (light underbrush)
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 18.23 minutes
Segment 3: Channel Flow
Length = 495.8 ft
Height = 24.3 ft
Slope = 0.0490 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 5.59 ft/sec
Segment Time = 1.18 minutes
C?
Segment 2: Concentrated Flow
Length = 91.4 ft
Height = 6.2 ft
Slope = 0.0678 ft/ft
Paved ? = No
Velocity = 4.20 ft/sec
Segment Time = 0.36 minutes
1 OF 2
•
•
•
CORBINTON COMMONS
EYC-06010
HYDROLOGIC CALCULATIONS
Pre-Development
B. IHNATOLYA, EI
11/13/2006
Time of Concentration = 20.07 minutes
SCS Lag Time = 12.04 minutes (SCS Lag = 0.6* Tc)
= 0.2007 hours
Time Increment = 3.49 minutes = 0.29*SCS Lag)
2OF2
•
CORBINTON COMMONS HYDROLOGIC CALCULATIONS
EYC-06010 Pre-Development
Note:
The studied watershed contains 98% HSG "B" soils and 2% HSG "C" soils.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
jT ervious 98
__nl1en 61_.__.__. Assume goood condition
Wooded 1 55 Assume good condition
1. SCS CURVE NUMBERS
11. PRE-DEVELOPMENT
- Subbasin ID
A. Watershed Breakdown
Contributing Area SCS CN ; Area jacresl Comments
On-site Open 61
_ 0.03 Assume good condition
On-site Wooded 55
...... ._........... _._._.____. .____...... .___
On-site Impervious 98 25.33

0.00 Assume good condition -
._.... .... ...._._.......
Off-site Open 61
Off-site Wooded 55 0.16
4.06 1 Assume good condition
Assume good on
Off-site Im ervious 98 0.22 -
C,
•
Total area = 29.80 acres
0.0466 sq.mi.
Composite SCS CN = 56
B. Time of Concentration Information
Time of concentration is calculated using SCS T R-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 1.7 ft
Slope = 0.0170 ft/ft
Manning's n = 0.40 woods (light underbrush)
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 21.61 minutes
Segment 3: Channel Flow
Length = 689.8 ft
Height = 32 ft
Slope= 0.0464 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 5.44 ft/sec
Segment Time = 2.11 minutes
Segment 2: Concentrated Flow
B. IHNATOLYA, El
11/20/2006
Length = 839 ft
Height = 68.8 ft
Slope = 0.0820 ft/ft
Paved ? = No
Velocity = 4.62 ft/sec
Segment Time = 3.03 minutes
Segment 4: Channel Flow
Length = 215.7 ft
Height = 6.2 ft
Slope = 0.0287 ft/ft
Manning's n = 0.045 channel
Flow Area = 6.00 sf (3'x2' channel)
Wetted Perimeter = 7.00 ft (3'x2' channel)
Channel Velocity = 5.07 ft/sec
Segment Time = t1. ?1 minutes
I OF 2
•
C7
•
CORBINTON COMMONS
EYC-06010
HYDROLOGIC CALCULATIONS
Pre-Development
B. IHNATOLYA, El
11/20/2006
Time of Concentration = 27.45 minutes
SCS Lag Time = 16.47 minutes (SCS Lag = 0.6* Tc)
= 0.2745 hours
Time Increment = 4.78 minutes (= 0.29*SCS Lag)
2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/14/2006
• 1. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is 'HSG B'.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments

_ ---_- Impervious
-,---.,-Impervious
98
?
Open
Wooded 61 f
55 Assume good condition _
Assume good condition
Roads including Right-of-Way
Residential-0.5 acre lots 89_-
70 _._____-_......... _
Residential-1.0 acre lots 68 -
•
11. PRE-DEVELOPMENT
_> Subbasin 2
A. Watershed Breakdown
Contributing Area SCS CN ! Area jacresi Comments
On-site Open 61 0.01 Assume good condition
.._ __. --_.. ...........
i
On site Wooded
O
I
i
. 55_
. 98 3.82
Assume good condition
0
01
n s
mpervious
te .
Off-site en 61 Assume good condition
1.75
Off-site Wooded
............. .....__._..______............ _...... __._____._._...__.._...._. 55
....._..____._.___...._... _
9.13 3 Assume good condition
.___._..___.____._._._
Off-site Impervious
...._...._ ..._.m...-........ 98
._. ... 0.48
Roads includin Ri t-of-Wa 89 4.16
- Residential-0.5 acre lots 70 7.45
Residential-1.0 acre lots 68 2.50 -
Total area = 29.31 acres
0.0458 sq.mi.
Composite SCS CN = 66
B. Time of Concentration Information
Time of concentration is calculated using SCS T R-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 0.5 ft
Slope = 0.0050 Rift
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 23.42 minutes
Segment 3:30" RCP
Length = 23.7 ft
Height = 0.6 It
Slope = 0.0253 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 13.33 ft/sec
Segment Time = 0.03 minutes

Segment 2: Concentrated Flow
Length = 175.1 ft
Height = 4.8 It
Slope = 0.0274 ft/ft
Paved ? = No
Velocity = 2.67 ft/sec
Segment Time = 1.04 minutes
Segment 4: Channel Flow
Length = 671.2 ft
Height = 38.2 ft
Slope = 0.0569 ft/ft
Manning's n = 0.045 channel
Flow Area = 2.00 sf (2'x 1' channel)
Wetted Perimeter = 4.00 ft (2'x 1' channel)
Channel Velocity = 4.98 ft/sec
Segment Time = 2.25 minutes
1 OF 2
•
•
CORBINTON COMMONS
EYC-06010
Segment 5:30" RCP
HYDROLOGIC CALCULATIONS
Pre-Development
Length = 29 ft
Height = 1.5 ft
Slope = 0.0517 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 19.06 ft/sec
Segment Time = 0.03 minutes
Segment 7. 30" RCP
Length = 14.4 ft
Height = 0.4 ft
Slope = 0.0278 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 13.96 ft/sec
Segment Time = 0.02 minutes
Segment 9:30" RCP
Length = 64.1 ft
Height = 2.5 ft
Slope = 0.0390 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter= 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 16.55 ft/sec
Segment Time = 0.06 minutes
Segment 6: Channel Flow
B. IHNATOLYA, El
11/14/2006
Length = 592.4 ft
Height = 24 ft
Slope = 0.0405 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 5.09 ft/sec
Segment Time = 1.94 minutes
Segment 8: Channel Flow
Length = 212.6 ft
Height = 8 ft
Slope = 0.0376 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 4,90 ft/sec
Segment Time = 0.72 minutes
Segment 10. Channel Flow
Length = 618.4 ft
Height = 17.9 ft
Slope = 0.0289 ft/ft
Manning's n = 0.045 channel
Flow Area = 30.00 sf (10'x3' channel)
Wetted Perimeter= 16.00 ft (10'x3' channel)
Channel Velocity = 8.57 ft/sec
Segment Time = 1.20 minutes
Time of Concentration = 30.77 minutes
SCS Lag Time = 18.46 minutes (SCS Lag = 0.6* Tc)
= 0.3077 hours
Time Increment = 5.35 minutes (= 0.29*SCS Lag)
•
2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/13/2006
• 1. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is 'HSG 13'.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
Impervious 98
..._.. _ . .........
O . n?mm 61 Assume good cond?t?on
Wooded 55 Assume good condition
11. PRE-DEVELOPMENT
_> Subbasin 3
A. Watershed Breakdown
Contributing Area SCS CN Area [acresl Comments
On-site Open 61 j 0.00 Assume good condition
...
On site Wooded 55 1.81 Assume p?ood condition
On site Impervious 98 0 00
..........

Off-site en 61
0.00
_ ......
Assume good condition _
_
Off site Wooded ?55 0.00 Assume good condition

Off-site Impervious 98
0.00 _
C7
Segment 2: Concentrated Flow
Length = 560.2 ft
Height = 33.6 ft
Slope = 0.0600 ft/ft
Paved ? = No
Velocity = 11.95 ft/sec
Segment Time = 2.36 minutes
Time of Concentration = 15.97 minutes
SCS Lag Time = 9.58 minutes (SCS Lag = 0.6* Tc)
0.1597 hours
Time Increment = 2.78 minutes (= 0.29*SCS Lag)
1r
u
Total area = 1.81 acres
0.0028 sq.mi.
Composite SCS CN = 55
B. Time of Concentration Information
Time of concentration is calculated using SCS T R-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 5.4 ft
Slope = 0.0540 ft/ft
Manning's n = 0.40 woods (light underbrush)
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 13.61 minutes
1 OF I
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/13/2006
49 1. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is'HSG B'.
SCS curve numbers were chosen accordingly.
Impervious 98
.......
_pen 61 Assume?od condition
Wooded 55 Assume good condition
IL PRE-DEVELOPMENT
_> Subbasin 4
A. Watershed Breakdown
Contributing Area SCS CN Area [acres] Comments
On-site Open
........... ..... _...._...._..._._ ..............................
On-site Wooded _ 61
......._...__..............._....__
55 0.00
.__._.._........... _._.._....._..._..
0.34 Assume good condition
...... ...................... ._. _.._._.._........
Assume good condition ?
On site Impervious

Off-sit?en 98

61 _ 0.00

0.00
-
....................... ......._. ....
_ Assume good condition _
Off--site Wooded 55 0.00 Assume o0 condition µ
Off site Im ervious 98 0.00 -
•
Segment 2: Concentrated Flow
Length = 123.7 ft
Height = 6.9 ft
Slope = 0.0558 ft/ft
Paved ? = No
Velocity = 3.31 ft/sec
Segment Time = 0.54 minutes
Time of Concentration = 13.86 minutes
SCS Lag Time = 8.31 minutes (SCS Lag = 0.6* Tc)
= 0.1386 hours
Time Increment = 2.41 minutes (= 0.29*SCS Lag)
•
Total area = 0.34 acres
0.0005 sq.mi.
Composite SCS CN = 55
B. Time of Concentration Information
Time of concentration is calculated using SCS T R-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 5.7 ft
Slope = 0.0570 ft/ft
Manning's n = 0.40 woods (light underbrush)
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 13.32 minutes
1 OF 1
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. tHNATOLYA, EI
EYC-06010 Pre-Development 11/7/2006
III. CHANNEL REACH DATA
• _> Subbasin WA-Reach #1
Segment #12-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
Segment #13-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time
•
Segment #14-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
•
Segment #15-Channel Flow
156.4 ft
0.05 ft
0.0003 ft/ft
0.045 Natural Channel
85.00 sf (Assume 17'x 5' Channel)
27.00 ft (Assume 17'x 5' Channel)
1.27 ft/sec
2.05 minutes
206.1 ft
2.2 ft
0.0107 ft/ft
0.045 Natural Channel
90.00 sf (18'x5' channel)
28.00 ft (18'x5' channel)
7.45 ft/sec
0.46 minutes
507.7 ft
9.9 ft
0.0195 ft/ft
0.045 Natural Channel
90.00 sf (18'x5' channel)
28.00 ft (18'x5' channel)
10.07 ft/sec
0.84 minutes
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15'x 5' Channel)
Wetted Perimeter = 25.00 ft (Assume 15'x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = 0.91 minutes
Reach #1 Total Travel Time = 4.26 minutes
_> Subbasin #1B-Reach #2
Segment #4-Channel Flow
Length = 75.5 ft
Height = 3.5 ft
Slope = 0.0464 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter= 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 18.04 ft/sec
Segment Time = 0.07 minutes
L`
•
CORBINTON COMMONS
EYC-06010
HYDROLOGIC CALCULATIONS
Pre-Development
B. IHNATOLYA, El
11/7/2006
Segment #5-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
Segment #6-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
Segment #7-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
Segment #8-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
Segment #9-Channel Flow
155.3
6.5
0.0419
0.045
4.00
6.00
5.17
0.50
32.7
0.6
0.0183
0.045
12.00
10.00
5.06
&I d
206.1
2.2
0.0107
0.045
90.00
28.00
7.45
0.46
507.7
9.9
0.0195
0.045
90.00
28.00
10.07
0.84
ft
ft
ft/ft
Natural Channel
sf (2'x2' channel)
ft (2'x2' channel)
ft/sec
minutes
ft
ft
ft/ft
Natural Channel
sf (3'x4' channel)
ft (3'x4' channel)
ft/sec
minutes
ft
ft
ft/ft
Natural Channel
sf (18'x5' channel)
ft (18'x5' channel)
ft/sec
minutes
ft
ft
ft/ft
Natural Channel
sf (18'x5' channel)
ft (18'x5' channel)
ft/sec
minutes
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15'x 5' Channel)
Wetted Perimeter = 25.00 ft (Assume 15' x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = 0.91 minutes

Reach #2 Total Travel Time = 2.89 minutes
0
CORBtNTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Pre-Development 11/7/2006
_> Subbasin #1 C-Reach #3
• Segment #4-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
Segment #5-Channel Flow
507.7
9.9
0.0195
0.045
90.00
28.00
10.07
0.84
ft
ft
ft/ft
Natural Channel
sf (18'x5' channel)
ft (I 8'x5' channel)
ft/sec
minutes
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15'x 5' Channel)
Wetted Perimeter = 25.00 ft (Assume 15'x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = 0.91 minutes

Reach #3 Total Travel Time = 1.75 minutes
-Subbasin #1D-Reach #4
Segment #5-Channel Flow
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
•
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15' x 5' Channel)
Wetted Perimeter = 25.00 ft (Assume 15'x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = A91 minutes
Reach #4 Total Travel Time = 0.41 minutes
0
HEC-HMS Project: EYC-06010 Basin Model:
•
Sub01 A SubOl S

Reach-1 Reach-2
Sub01 C3
Sub01C

• Reach-4 F;
Reach-3
Sup 0Z Sut;5 Sub02
POA #1

0
HMS * Summary of Results
Project : EYC-06010 Run Name : 30-Year Pre
• Start of Run : 16Aug06 1200 Basin Model : Pre-Development
End of Run : 17Aug06 1200 Met. Model : 10-Year Storm
Execution Time : 20Nov06 0852 Control Specs : 1-Min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
SubO1D 27.149 17 Aug 06 0022 3.0609 0.047
Reach-4 27.149 17 Aug 06 0022 3.0609 0.047
SubOlA 604.40 17 Aug 06 0032 78.469 0.596
Reach-1 604.40 17 Aug 06 0036 78.385 0.596
SubO1B 44.417 17 Aug 06 0011 3.3401 0.032
Reach-2 44.417 17 Aug 06 0013 3.3382 0.032
SubO1C 11.601 17 Aug 06 0016 1.1052 0.016
Reach-3 11.601 17 Aug 06 0017 1.1048 0.016
POA #1 643.87 17 Aug 06 0035 85.889 0.690
Sub02 45.360 17 Aug 06 0022 4.8231 0.046
Sub03 1.9368 17 Aug 06 0013 0.17436 0.003
Sub04 0.36608 17 Aug 06 0012 0.031154 0.001
•
•
•
POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS
u

CORBINTON COMMONS
EYC-06010
•
•
•
CORBINTON COMMONS
EYC-06010
1. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post-Development
Note:
The studied watershed contains 76% HSG "B" soil s, 10% HSG "C" soils, and 14% HSG "D" soils.
SCS curve numbers were chosen accordingly.

Cover Condition
I --
SCS CN
7
Comments
Impervious 98
_ -

Open
65 _
Assume?ood condition
Wooded 60, j Assume good condnion
Commercial u
Roads including Ri ht of-Wa 90
Residential-0.25 acre lots 77 i
Residential-0.5 acre lots 73
.........
Residential-1.0 acre lots
............. .............
71

Residential-2.0 acre lots
69 .............
II. POST-DEVELOPMENT
=>Subbasin IA
A. Watershed Breakdown
Contributing Area SCS CN
? i Area lacresi Comments
On site Open 65 0 00 ? Assume good condition

site
Wooded
On-
60
0
00
Assume good.condmon
site
Im
erv?ous 98 0
.00
W ?
On-Site Commercial 1 93 0.00
..._........._...._._....._Off site Open_..__....... __..._.__.__...j _._.._ 65 73.66 Assume p 2o4 ,condition
_
Off-site Wooded 60 100.92 Assume good condition
Off-site Impervious ._ _. m 98 7.71
Off-Site Commercial mm
93 46.72
Roads including Right-of-Way
_ _._.._ _.._-- 90 22.89
.

Residential-0.25 acre lots ._-____

77 _

9.46 ._. ................ _..... ....
_
Residential-0.5 acre lots
Residential-1.0 acre lots 73
71 58.90
42.53
Residenhal-2.0 acre lots 69 ) 17.67 t
Off Site Pond 100 1.12
Total area = 381.58 acres
0.5962 sq.mi.
Composite SCS CN = 72
B. Time of Concentration Information
Time oj'concentration is calculated using SCS TR-55.
Segment l: Overland Flow
Length = 100 ft
Height = 0.4 ft
Slope = 0.0040 ft/ft
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 25.61 minutes
Segment 3: Channel Flow
Length = 869.8 ft
Height = 26 ft
Slope = 0.0299 ft/ft
Manning's n = 0.045 channel
Flow Area = 6.00 sf (3'x2' channel)
Wetted Perimeter = 7.00 ft (3'x2' channel)
Channel Velocity = ft/sec
Segment Time = 1.81 minutes
Segment 2: Concentrated Flow
Length = 208.1 ft
Height = 0.8 ft
Slope = 0.0038 ft/ft
Paved ?= No
Velocity = 1.0(i ft/sec
Segment Time = 3.47 minutes
B. IHNATOLYA, El
11/20/2006
Segment 4. 30"RCP
Length = 149.3 ft
Height = 2 ft
Slope = 0.0134 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 It
Channel Velocity= 9.70 ft/sec
Segment Time = 0.26 minutes
I OF 2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/20/2006
Segment S. Channel Flow
Length = 741.8 ft
Height = 21.9 ft
Slope = 0.0295 ft/ft
Manning's n = 0.045 channel
Flow Area = 6.00 sf (3'x2' channel)
Wetted Perimeter = 7.00 ft (3'x2' channel)
Channel Velocity= 5.13 ft/sec
Segment Time = 2.41 minutes
Segment 7: Channel Flow
•

Length = 575.6 ft
Height = 12.2 ft
Slope = 0.0212 ft/ft
Manning's n = 0.045 channel
Flow Area = 12.00 sf (4'x3' channel)
Wetted Perimeter = 10.00 ft (4'x3' channel)
Channel Velocity = 5.44 ft/sec
Segment Time = 1.76 minutes
Segment 9: Channel Flow
Length = 2584.9 ft
Height = 35.3 ft
Slope= 0.0137 ft/ft
Manning's n = 0.045 channel
Flow Area = 16.00 sf (4'x4' channel)
Wetted Perimeter = 12.00 ft (4'x4' channel)
Channel Velocity = 4.69 ft/sec
Segment Time = 9.19 minutes
Segment I1: Channel Flow
Length = 98.4 ft
Height = 2.35 ft
Slope = 0.0239 ft/ft
Manning's n = 0.045 channel
Flow Area = 85.00 sf (17'x5' channel)
Wetted Perimeter = 27.00 ft (I Tx5' channel)
Channel Velocity = 10.99 ft/sec
Segment Time = 0.15 minutes
Time of Concentration = 46.15 minutes
SCS Lag Time = 27.69 minutes (SCS Lag = 0.6* Tc)
= 0.4615 hours
Time Increment = 8.03 minutes (= 0 29*SCS Lag)
Segment 6: 30" RCP
Length = 65.6 ft
Height = 0.1 ft
Slope = 0.0015 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 3.21,11 ft/sec
Segment Time = 0.33 minutes
Segment 8: 30" RCP
Length = 55.4 ft
Height = 1.8 ft
Slope = 0.0325 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 15.10 ft/sec
Segment Time = 0.06 minutes
Segment 10: 30" RCP
Length = 126.3 ft
Height = 8.4 ft
Slope = 0.0665 tI/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 21.61 ft/sec
Segment Time = 0.10 minutes
2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/14/2006
1. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is 'HSG B'.
SCS curve numbers were chosen accordingly.
?o -
61 Assumed condition
Wooded 55 Assume good condition
Roads includinftht-of-Way 89
Residential-0.5 acre lots 70 -
Residential-1.0 acre lots
Residential-2.0 acre lots 68 -
65 -
•
11. POST-DEVELOPMENT
_> Subbasin I B
A. Watershed Breakdown
Contributing Area SCS CN Area ]acres] Comments
On-site Open _ 61 0.00 Assume good condition
Wooded 55 0.00 Assume good condition
On-site 98 0.00
Off-site Open F-76-17-7 2.68 Assume good condition
------- --__.
Off site Wooded _ 55 2.96 Assumed condition
w Off-site Impervious 98
0.28
Roads including Right-of-Way
....... ... _.. 89 1.14

Residential-0.5 acre lots
70
2.46 ...... .. ...._..

Residential-1.0 _acre lots
_ ..
68 1 ._ _.. _.._
7.10 .. ..._. ......... ...... .............
Residential-2.0 acre lots 65 3.60 _. -?-
Total area = 20.22 acres
0.0316 sq.mi.
Composite SCS CN = 66
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 6.2 ft
Slope = 0.0620 ft/ft
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 8.56 minutes
Segment 3: Channel Flow
Length = 1302.4 ft
Height = 79.5 ft
Slope = 0.0610 ft/ft
Manning's n = 0.045 channel
Flow Area = 2.00 sf (2'x P channel)
Wetted Perimeter = 4.00 ft (2'x P channel)
Channel Velocity = 5,15 ft/sec
Segment Time = 4.21 minutes
•
Segment 2: Concentrated Flow
Length = 348.8 ft
Height = 18.3 ft
Slope = 0.0525 ft/ft
Paved ? = No
Velocity = 3.70 ft/sec
Segment Time = 1.57 minutes
1 OF 2
•
.7
1?
CORBINTON COMMONS
EYC-06010
HYDROLOGIC CALCULATIONS
Post-Development
B. IRNATOLYA, El
11/14/2006
Time of Concentration = 14.34 minutes
SCS Lag Time = 8.61 minutes (SCS Lag = 0.6* Tc)
= 0.1434 hours
Time Increment = 2.50 minutes (= 029*SCS Lag)
2OF2
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/13/2006
0 I. SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is'HSG B'.
SCS curve numbers were chosen accordingly.
en 61 1 Assume good condition
Wooded 55 Assume good condition
...... ............. -.1--- ........ . .... . # ... I
Impervious 98 i -

11. POST-DEVELOPMENT
_> Subbasin IC-To WQ Pond #1
A. Watershed Breakdown
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0.29*SCS Lag)

Contributing Area J
t SCS CN ( Area jacresl !
? Comments
On-site Open 61 2.08 3 Assume good condition
On-site Wooded
...... _._.. 55 [ 0.00 Assume good condition

_ On site Impervious

98 _..._
4.01
? _. .

-
On Site Pond
_.... 100 1 0.22

Off site Open
61
0 04 _ ..................... _
Assume ood condition
Off-site Wooded 55 0.00 i Assume good condition
Off-site Impervious 98 0.13
Off-Site Pond 100 0.00
Total area = 6.48 acres
0.0101 sq.mi.
Composite SCS CN = 86
% Impervious = 63.9%
B. Time of Concentration Information
Time of concentration was assumed to be a conservative 5 minutes
I OF i
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/14/2006
• 1. SCS CURVE NUMBERS
Note:
The studied watershed contains 82% HSG "B" soils and 18% HSG "C" soils.
SCS curve numbers were chosen accordingly.
Cover Condition ( SCS CN ( Comments
Open 63 ! Assume good condition
Wooded 58 Assume good condition
Impervious 9$-
? ?
11. POST DEVELOPMENT
_> Subbasin 1 C-WQ Pond #1 Bypass
A. Watershed Breakdown
Contributing Area SCS CN Area lacresl Comments
_ On-site Oven _ 63 0.84 j Assume good condition
On site Wooded 58 2.33 Assume good condition
On site Im ernous 98 0.15 ;
4 -
On-Site Pond 100 0.000

Off-site Open
63
0.26 ---------- -- -
Assume good condition
Off-site Wooded
____..__....._..___._._........___....... .......... .............__------- ..._.._ 58
.__............._.._.._. 0.62 Assume good condition
_...... __...._......__._._._ ___._..__.._._._.__._._._..........._..........._.
Off-site Impervious i
___ 98 0.33
...__.._
Off-Site Pond - F...._._.. 100_ 0.00
Total area = 4.53 acres
0.0071 sq.mi.
• Composite SCS CN = 63
% Impervious = 10.6%
B. Time of Concentration Information
Time of concentration was assumed to be a conservative 5 minutes
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0 29*SCS Lag)

1 OF 1
•
CORBINTON COMMONS
EYC-06010
1. SCS CIiRVE NI IvIRERS
HYDROLOGIC CALCULATIONS
Post-Development
Note:
The predominant hydrologic soil group within the studied watersheds is 'HSG B'.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
Impervious 98 Assume good condition
o 51 Assume good condition
d
(L POST-DEVELOPMENT
_> Subbasin ID-To WQ Pond #2
A. Watershed Breakdown
Total Number of Residential Lots = 25 lots
Assumed Impervious Area Per Residential Lot = 2600 square feet
Total Im ervious Area from Residential Lots = 1.49 acres
_....._..__._.___.__.__.....___.. _......__._k _...__......_....._.._.._.......__.______......___........__..__ _._..___m.._..._.__._.._.m....____._ .......... ....... ........
Total Number of Townhouse Lots = 44 lots
............... __...... ______.._.___.____.._._ ...... ..-_....__.___._
Assumed Im ervious Area Per Townhouse Lot = 1500 s uare feet
Total Impervious Area from Townhouse Lots = 1.52 acres
•
Contributing Area SCS CN Area [acres] Comments
On-site en 61 7.30 Assume good condition
On site Wooded 55 0.00 Assume good condition
On site Impervious 98 7.27
On-Site Pond
.. .. 100 0.57

mm Off-site Open _
61 . _.._..........
0.00 . _ __.W._. __ ............. ___. ....__....................................
Assume good condition
Off site Wooded 55 0.00 Assume good condition
Offsite
Impervious 98 0.00 '
.
....___......_
._._......... .
Off-Site Pond
100 .__
__...
0.00 .._._....______.........._...._._._.____.._
_........ _
Total area = 15.14 acres
0.0237 sq.mi.
Composite SCS CN = 80
% Impervious = 48.0%
B. Time of Concentration Information
Time of concentration was assumed to be a conservative 5 minutes
B. IHNATOLYA, El
11/14/2006
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0 29*SCS Lag)

1 OF 1
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/13/2006
I. SCS CURVE NUMBERS
Note:
The studied watershed contains 92% HSG "B" soils and 8% HSG "C" soils.
SCS curve numbers were chosen accordingly.
Condition
U en 62 i Assume good condition
Wooded 56 ( Assume good condition
....... ____. ....... ._...._,...._.__....... _...____......__..._.____.. _.......
__..__.,.__..._.
Impervious 98 -
It. POST-DEVELOPMENT
_> Subbasin 1 D-WQ Pond #2 Bypass
A. Watershed Breakdown
Contributing Area SCS CN Area Iacresl Comments
On-site en 62 2.30 Assume ood condition
On-site Wooded
.. .... _ _ 56 4.83 Assume good condition
On-site Impervious
On-Site Pond
__........._..__.__...__.__._m...-..._..__.._____. 98
100 0.79
0 00 -
-

Off-site Open
62
0.13 -------
Assume ood condition
......_.._._._O .-site Wooded _.___.. _ _56__. 0.85 Assume good condition
Off-site Impervious 98 0.21
Off-Site Pond 100 0.00 -
Total area = 9.11 acres
0.0142 sq.mi.
• Composite SCS CN = 62
% Impervious = 11.0%
B. Time of Concentration Information
Time of concentration was assumed to be a conservative 5 minutes
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0.29*SCS Lag)

I OF 1
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/14/2006
• I. SCS'CURVE NUMBER'S
Note:
The predominant hydrologic soil group within the studied watersheds is 'HSG B'.
SCS curve numbers were chosen accordingly.
Cover Condition j SCS CN Comments
_.....-Impervious
..... ._ ................................... ;..........._98....
............ .........
....._............._...._.__.._.....__..._._.... _............... ...._........ _._....__._..._..._.
P
en _ 61 Assume good condition
Wooded
....... _... _ ....._.... __. .. 55
_ ......... _ _...._....... Assume good condition
_........
Roads includin Ri ht-of-W Y _ _ _89

Residential-0.5 acre lots
....... __...._........
.___..__..._.____.-..__..._.__
1 70

._..._ ?
Residential-1.0 acre lots 68 -
•
If. POST-DEVELOPMENT
=> Subbasin 2 77-1
A. Watershed Breakdown
-? Contributing Area SCS CN Area ' Comments
[acres]
On-site en 61
_._._..... __._.. 1.19 Assume good condition - -
_........ . .......
On-site Wooded _55 1.63 Assume ood condition
On-site hn ervious 98 0.17 -
_Off-site Open 61 1.72 Assume good condition
" Off site Wooded 55 9.02 Assume good condition
Off-site Impervious 98
_.......... 1_-_--.-
Roads including Right of Way 89
_...._.._...___ 0.62

4.16

.

Residential-0.5 acre lots 70
- -m
7.45 __._.__._.-._.__._.....______..__..
Residential-1.0 acre lots 68 _ 2.50 ?-
Total area = 28.46 acres
0.0445 sq.mi.
Composite SCS CN = 67
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55 .
Segment 1: Overland Flow
Length = 100 ft
Height = 0.5 ft
Slope = 0.0050 ft/ft
Manning's n = 0.24 dense grasses
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 13.42 minutes
Segment 3:30" RCP
Length = 23.7 ft
Height = 0.6 ft
Slope = 0.0253 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter= 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 1133 ft/sec
Segment Time = 0.03 minutes
Segment 2: Concentrated Flow
Length = 175.1 ft
Height = 4.8 ft
Slope = 0.0274 ft/ft
Paved ? = No
Velocity = 2.67 ft/sec
Segment Time = 1.09 minutes
Segment 4: Channel Flow
Length = 671.2 ft
Height = 38.2 ft
Slope = 0.0569 ft/ft
Manning's n = 0.045 channel
Flow Area = 2.00 sf (2'x1' channel)
Wetted Perimeter= 4.00 ft (2'x1' channel)
Channel Velocity = 4.98 fl/sec
Segment Time = 2.25 minutes
0
11
•
CORBINTON COMMONS
EYC-06010
Segment S: 30" RCP
HYDROLOGIC CALCULATIONS
Post-Development
Length = 29 ft
Height = 1.5 ft
Slope = 0.0517 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 19.06 ft/sec
Segment Time = 0.03 minutes
Segment 7. 30 RCP
Length = 14.4 ft
Height = 0.4 ft
Slope = 0.0278 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 13.96 ft/sec
Segment Time = 0.02 minutes
Segment 9: 30" RCP
Length = 64.1 ft
Height = 2.5 ft
Slope = 0.0390 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter= 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 16.55 ft/sec
Segment Time = 0.06 minutes
Segment 6: Channel Flow
B. IHNATOLYA, El
11/14/2006
Length = 592.4 ft
Height = 24 ft
Slope = 0.0405 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter= 6.00 ft (2'x2' channel)
Channel Velocity = 5.09 ft/sec
Segment Time = 1.94 minutes
Segment 8: Channel Flow
Length = 212.6 ft
Height = 8 ft
Slope = 0.0376 ft/ft
Manning's n = 0.045 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 4.90 ft/sec
Segment Time = 0.72 minutes
Segment 10: Channel Flow
Length = 618.4 ft
Height = 17.9 ft
Slope = 0.0289 ft/ft
Manning's n = 0.045 channel
Flow Area = 30.00 sf (10'x3' channel)
Wetted Perimeter= 16.00 ft (10'x3' channel)
Channel Velocity = 8.57 ft/sec
Segment Time = 1.20 minutes
Time of Concentration = 30.77 minutes
SCS Lag Time = 18.46 minutes (SCS Lag = 0.6* Tc)
= 0.3077 hours
Time Increment = 5.35 minutes (= 0.29*SCS Lag)
•
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. 1HNATOLYA
EYC-06010 Post-Development 11/13/2006
• L SCS CURVE NUMBERS
Note:
The predominant hydrologic soil group within the studied watersheds is'HSG B'.
SCS curve numbers were chosen accordingly.
over Condition SCS CN Comments
O en 61 Assume good condition
_Wooded_ 55 Assume good condition
impervious 98
11. 'POST-DEVELOPMENT
_> Subbasin 3
A. Watershed Breakdown
Contributing Area
E SCS CN Area ]acres] I Comments
On-site Open 61 1.06 Assume good condition
On-site Wooded

On-site hn ervious 55

98 ` 2.881

0.24 Assume good condition
- -------------
Off-site Open
Off-site Wooded_.__ 61
_____55-._.. 0.00
--_ 3.23_-
? Assume ood condition

Assume ood condition
Off-site Impervious 98 0.02
Off-Site Pond - 100 0.00
•
Segment 2: Concentrated Flow
Length = 447.6 ft
Height = 39 ft
Slope = 0.0871 ft/ft
Paved ? = No
Velocity = 4.76 ft/sec
Segment Time = 1.5? minutes
Time of Concentration = 25.60 minutes
SCS Lag Time = 15.36 minutes (SCS Lag = 0.6* Tc)
= 0.2560 hours
Time Increment = 4.45 minutes (= 0.29*SCS Lag)
Total area = 7.36 acres
0.0115 sq.mi.
Composite SCS CN = 57
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 dense grasses
Height = 1.7 ft
Slope = 0.0170 ft/ft
Manning's n = 0.40 woods (light underbrush)
P (2-year/24-hour) = 3.6 inches (Wake/Durham County)
Segment Time = 2L61 minutes
Segment 3: Channel Flow
Length = 1258.5 ft
Height = 65.5 ft
Slope = 0.0520 ft/ft
Manning's n = 0.030 channel
Flow Area = 4.00 sf (2'x2' channel)
Wetted Perimeter = 6.00 ft (2'x2' channel)
Channel Velocity = 8.65 ft/sec
Segment Time = 2.43 minutes
r?
•
CORBINTON COMMONS
EYC-06010
1. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post-Development
Note:
The predominant hydrologic soil group within the studied watersheds is'HSG B'.
SCS curve numbers were chosen accordingly.
Cover Condition SCS CN Comments
en 61 Assume good condition
Wooded _5_5 Assume od condition
impervious 98
[I. POST-DLVELOPMENT
_> Subbasin 4
A. Watershed Breakdown
Contributing Area SCS CN Area (acres Comments
On-site Open 61 0.13 Assume ood condition
On-site Wooded
On-site hn ervious 55
98 0.18
0.03 Assume good condition
-
Off-site Open
Off-site Wooded 61
55 000
0.00 Assume good condition
Assume ood condition
Off-site Impervious 98 mm 0.00 -
Off-Site Pond 100 0.00 -
Total area = 0.34 acres
0.0005 sq.mi.
Composite SCS CN = 61
•
B. Time of Concentration Information
Time of concentration was assumed to be a conservative 5 minutes
B. IHNATOLYA
11/13/2006
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0.29*SCS Lag)
0
CORBINTON COMMONS HYDROLOGIC CALCULATIONS B. IHNATOLYA, El
EYC-06010 Post-Development 11/9/2006
Ill.. CHANNEL REACH DATA
• °> Subbasin #]A-Reach #1

Segment #12-Channel Flow
Length = 156.4 ft
Height = 0.05 ft
Slope = 0.0003 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 85.00 sf (Assume IT x 5' Channel)
Wetted Perimeter = 27.00 ft (Assume 17'x 5' Channel)
Channel Velocity = 1.27 ft/sec
Segment Time = 2.05 minutes
Segment #13-Channel Flow
Length = 206.1 ft
Height = 2.2 ft
Slope = 0.0107 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 90.00 sf (I 8'x5' channel)
Wetted Perimeter = 28.00 ft (18'x5' channel)
Channel Velocity = 7.4 ft/sec
Segment Time = 0.46 minutes
Segment #14-Channel Flow
Length = 507.7 ft
Height = 9.9 ft
Slope = 0.0195 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area= 90.00 sf(I8'x5'channel)
• Wetted Perimeter= 28.00 ft (18'x5' channel)
Channel Velocity= 10.07 ft/sec
Segment Time = 0.14 minutes
Segment #15-Channel Flow
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15'x 5' Channel)
Wetted Perimeter = 25.00 ft (Assume 15'x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = 291 minutes
Reach #1 Total Travel Time = 4.26 minutes
_> Subbasin #I B-Reach #2
Segment #4-Channel Flow
Length = 75.5 ft
Height = 3.5 ft
Slope = 0.0464 ft/ft
Manning's n = 0.013 RCP
Flow Area = 4.91 sf (Assume a 30" RCP)
Wetted Perimeter = 7.85 ft (Assume a 30" RCP)
Hydraulic Radius = 0.63 ft
Channel Velocity = 18.04 ft/sec
• Segment Time = 0.11" minutes
•
F- I
L
CORBINTON COMMONS
EYC-06010
Segment #5-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time
Segment #6-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time
Segment #7-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
Segment #8-Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
Segment #9-Channel Flow
HYDROLOGIC CALCULATIONS
Post-Development
155.3 ft
6.5 ft
0.0419 ft/ft
0.045 Natural Channel
4.00 sf (2'x2' channel)
6.00 ft (2'x2' channel)
5.17 ft/sec
1.50 minutes
32.7
0.6
0.0183
0.045
12.00
10.00
5.06
0.11
206.1
2.2
0.0107
0.045
90.00
28.00
7.45
0.46
507.7
9.9
0.0195
0.045
90.00
28.00
10.07
0.84
ft
ft
ft/ft
Natural Channel
sf (3'x4' channel)
ft (3'x4' channel)
ft/sec
minutes
ft
ft
ft/ft
Natural Channel
sf (18'x5' channel)
ft (18'x5' channel)
ft/sec
minutes
ft
ft
ft/ft
Natural Channel
sf (I 8'x5' channel)
ft (I 8'x5' channel)
ft/sec
minutes
Length = 381.7 ft
Height = 3.9 ft
Slope = 0.0102 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 75.00 sf (Assume 15'x 5' Channel)
Wetted Perimeter= 25.00 ft (Assume 15'x 5' Channel)
Channel Velocity = 6.96 ft/sec
Segment Time = 0.91 minutes

Reach #2 Total Travel Time = 2.89 minutes
B. IHNATOLYA, El
11/9/2006
C,
•
0
HEC-HMS
`ubbasm-1 J-To Pond
Reach-1 /) Reach-2
Pond #2 Pond #1
Subbwin-I D-Pond Ryu 15ubba3fn-iC-Pand Byp
Subbasirr-a S fair:-3 Subbasan-2
P POA#1
Project: EYC-06010
Subbasir,•tA Subbasin-1B
-
Subbase-1C-To Pond
Basin Model:
0
HMS * Summary of Results
Project : EYC-0601 0 Run Name : 10-Year Post
. Start of Run
16A
06 120
i
:
ug 0 Bas
n Model : Post-Development
End of Run : 17Aug06 1200 Met. Model : 10-Year Storm
Execution Time : 20Nov06 0853 Control Specs : 1-Min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Subbasin-ID-TO Pond 72.923
Pond #2 3.2954
Subbasin-lA 604.40
Reach-1 604.40
Subbasin-1B 44.417
Reach-2 44.417
Subbasin-lC-To Pond 36.222
Pond #1 14.628
Subbasin-iD-Pond By; 21.785
Subbasin-lC-Pond Byp 11.480
POA#1 636.37
Subbasin-2 46.154
Subbasin-3 7.4698
0 ibbasin-4 0.72593
17 Aug 06 0004 4.0703 0.024
17 Aug 06 0235 1.2505 0.024
17 Aug 06 0032 78.469 0.596
17 Aug 06 0036 78.385 0.596
17 Aug 06 0011 3.3401 0.032
17 Aug 06 0013 3.3382 0.032
17 Aug 06 0004 2.0556 0.010
17 Aug 06 0014 1.7704 0.010
17 Aug 06 0005 1.2673 0.014
17 Aug 06 0005 0.66259 0.007
17 Aug 06 0035 86.674 0.683
17 Aug 06 0022 4.8778 0.044
17 Aug 06 0020 0.79815 0.012
17 Aug 06 0005 0.042614 0.001
0
E
WATER QUALITY POND #1 FINAL DESIGN
CALCULATIONS
•
•
CORBINTON COMMONS
EYC-06010
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CORBINTON COMMONS
EYC-06010
Stage-Storal
Project Name:
Designer:
Job Number:
Date:
Fe Function
Corbinton Commons
B. Ihnatolya, El
EYC-06010
11/8/2006
B. IHNATOLYA, El
11/16/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet) (feet) (SF) (SF) (CF) (CF) (feet)
521.0 0.0 9449
522.0 1.0 10383 9916 9916 9916 1.01
524.0 3.0 12298 11341 22681 32597 2.95
526.0 5.0 14325 13312 26623 59220 5.06
11
Storage vs. Stage
70000 ?-
60000
y = 9856.3x1 1061
50000
LL R2 = 0.9997
v 40000--
30000--
N ?
0
20000
--
10000--
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0
Stage (feet)
Ks = 9856.3
b = 1.1061
r
•
•
CORBINTON COMMONS
EYC-06010
=> Stage - Storage Function
Ks= 9856.3
b= 1.1061
Zo = 521
521 0 I 0.000
_521.2
521.4

521.6 1662
3577
..... ...___.-
5602 0.038
0.082
__.._..,..-., _._._.1..
0.129
521.8 7701 0.177
522 9856 0.226
522.2
522.4 _ 12059
14300 0.277
0.328
522.6 16576 0.381
522.8 18883 0.433
523 21217 0.487
523.2 23576 0.541_
523.4 25958 0.596
523.6 28361 0.651
523.8
52_4_ 30783
33224 0.707
0.763
524.2 _ 35683 0.819
524.4 38158 0.876
524.6 406
48 0.933
524.8 _
_
43153 0.991
525 45672 1.048
525.2 48205 1.107
525.47
525.6 50750
53308 1.165
1.224
525.8 55877 1.283
526 58458 1.342
B. IHNATOLYA, El
11/16/2006
0
•
Type.... Outlet Input Data Page 1.01
Name.... Pond #1
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 521.00 ft
Increment = .20 ft
Max. Elev.= 526.00 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 OR ---> TW 521.000 526.000
Inlet Box RI ---> BA 522.300 526.000
Culvert-Circular BA ---> TW 516.500 526.000
TW SETUP, DS Channel
•
•
SIN: 6217012070C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 4:31 PM Date: 11/16/2006
1/ 1I
u
Type.... Outlet Input Data
Name.... Pond #1
Page 1.02
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of Openings = 1
Invert Elev. = 521.00 ft
Diameter = .1250 ft
Orifice Coeff. _ .600
•
•
Structure ID = RI
Structure Type
----------------- = Inlet Box
-------------
------
# of Openings = 1
Invert Elev. = 522.30 ft
Orifice Area = 16.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 16.00 ft
Weir Coeff. = 3.000
K, Submerged = .000
K, Reverse = 1.000
Kb,Barrel = .000000 (per ft of
Barrel Length = .00 ft
Mannings n = .0000
SIN: 6217012070C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 4:31 PM
full flow)
Date: 11/16/2006
•
Type.... Outlet Input Data
Name.... Pond #1
Page 1.03
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = BA
Structure Type
----------------- = Culvert-Circular
-------------------
No. Barrels = 1
Barrel Diameter = 1.2500 ft
Upstream Invert = 516.50 ft
Dnstream Invert = 516.00 ft
Horiz. Length = 63.00 ft
Barrel Length = 63.00 ft
Barrel Slope = .00794 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .023225
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) = 1.157
T2 ratio (HW/D) = 1.303
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 = 517.95 ft ---> Flow = 4.80 cfs
At T2 Elev = 518.13 ft ---> Flow = 5.49 cfs
r?
L
SIN: 6217012070C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 4:31 PM Date: 11/16/2006
•
Type.... Outlet Input Data
Name.... Pond #1
Page 1.04
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
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
•
•
SIN: 6217012070C3
PondPack Ver. 8.0058
The John R. McAdams Company
Time: 4:31 PM Date: 11/16/2006
L`
•
•
Type.... Composite Rating Curve
Name.... Pond #1
Page 1.10
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
WS Elev, Total Q
Elev. Q
ft
------ cfs
--
521.00 -------
.00
521.20 .02
521.40 .03
521.60 .04
521.80 .05
522.00 .06
522.20 .06
522.30 .07
522.40 1.59
522.60 7.96
522.80 13.56
523.00 13.80
523.20 14.04
523.40 14.28
523.60 14.51
523.80 14.74
524.00 14.96
524.20 15.19
524.40 15.40
524.60 15.62
524.80 15.83
525.00 16.04
525.20 16.25
525.40 16.45
525.60 16.65
525.80 16.85
526.00 17.05
SIN: 6217012070C3
PondPack Ver. 8.0058
***** COMPOSITE OUTFLOW SUMMARY ****
-------- Converge
TW Elev Error
ft +/-ft
-------- -----
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Notes
-------------------------
Contributing Structures
(no Q: OR,RI,BA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
The John R. McAdams Company
Time: 4:30 PM Date: 11/16/2006
HKS * Summary of Results for Pond #1
u
Project : EYC-06010
Start of Run : 16Aug06 1200
End of Run : 17Aug06 1200
Execution Time : 16Nov06 1800
Run Name : 10-Year Post
•
Basin Model Post-Development
Met. Model 10-Year Storm
Control Specs 1-Min dT
Computed Results
Peak Inflow : 36.222 (cfs)
Peak Outflow : 14.628 (cfs)
Total Inflow : 3.82 (in)
Total Outflow : 3.29 (in)
Date/Time of Peak Inflow 17 Aug 06 0004
Date/Time of Peak Outflow 17 Aug 06 0014
Peak Storage : 0.67975(ac-ft)
Peak Elevation : 523.70(ft)
0
HMS * Summary of Results for Pond #1
•
Project : EYC-06010
Start of Run 16Aug06 1200
End of Run 17Aug06 1200
Execution Time 16Nov06 1801
Run Name : 100-Year Post
•
Basin Model Post-Development
Met. Model 100-Year Storm
Control Specs 1-Min dT
Computed Results
Peak Inflow : 53.498 (cfs)
Peak Outflow : 16.075 (cfs)
Total Inflow : 6.32 (in)
Total Outflow : 5.78 (in)
Date/Time of Peak Inflow 17 Aug 06 0004
Date/Time of Peak Outflow 17 Aug 06 0019
Peak Storage 1.0577(ac-ft)
Peak Elevation 525.03(ft)
0
CORBINTON COMMONS
EYC-06010
Stage -
Ks =
b=
Z0= Storage Fu
9856.3
1.1061
521 nction
Elevation
[feet] Sto
[cf] rage
[acre-fe,
P

522.3 13175 0.302
522.5 15434 0.354
522.7 {
522.9 17726
E 20047 _0.4_07
0.460
53.1
523.3
523.5
523.7 22393
4764
27157
29570 0.514
0.569
0.623
0.679
523.9
_ 32002 0.735
524.1 34452 0.791
524.3 36918 0.848
524.5 39401 0.905
524.7 41899
_ 0.962
_524.9 1
_525.
_ 525.3 44411
1__ m-
49476 1.020
1.078
1.136
525.5 52027
M 1.194
525 54591 1.253
525.9
526 57166
58458 1.312
1.342
•
B. IHNATOLYA, El
11/16/2006
100-YR S-S Function-Clogged Siphon Condition
Elevation
522.3 0 0.000
22.5 s 2259 0.052
522.7 ' 4551 ?0.104
522.9 6872 0.158
523.1 9219 0.212
523 3 11589 0 266
523.5 13982 0.321
523.7 16395 0.376
523.9 18827 0.432
524.1 21277 0.488
524.3 23743 0.545
524.5 26226 0.602
6

524.7
28724 _.
.
0.659
524.9 1 31236 0.717 V
525.1 33762 0
775
.
525.3 36301 0.833
525.5 38853 0.892
_ 525.7 41416 951
525 9 43991 1 1.010
526.0 45283 € 1.040
I 1
rI
•
Type.... Composite Rating Curve
Name.... Pond #1-WC
Page 1.09
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments: _ v.-itv _7vse/./,AR6 E
***** COMPOSITE OUTFLOW SUMMARY ***
WS Elev, Total Q
Elev. Q
ft cfs
--------
522.30 -------
.00
522.50 4.29
522.70 12.14
522.90 13.60
523.10 13.84
523.30 14.07
523.50 14.30
523.70 14.53
523.90 14.75
524.10 14.97
524.30 15.19
524.50 15.40
524.70 15.61
524.90 15.82
525.10 16.03
525.30 16.23
525.50 16.43
525.70 16.63
525.90 16.82
526.00 16.92
? OU
Cu?evE
Notes
------ -- Converge -------------------------
TW Elev Error
ft +/-ft Contributing Structures
------
Free -- -----
Outfall --------------------------
(no Q: RIBA)
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RI,BA
Free Outfall RIBA
Free Outfall RI,BA
Free Outfall RI,BA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RI BA
Free Outfall RI,BA
Free Outfall RIBA
Free Outfall RIBA
SIN: 621701207003
PondPack Ver. 8.0058
The John R. McAdams Company
Time: 4:31 PM Date: 11/16/2006
HMS * Summary of Results for Pond #1
Project : EYC-06010 Run Name : 100-YR-WC
• Start of Run : 16Aug06 1200 Basin Model Worst Case
End of Run : 17Aug06 1200 Met. Model 100-Year Storm
Execution Time : 16Nov06 1803 Control Specs 1-Min dT
Computed Results
Peak Inflow 53.498 (cfs) Date/Time of Peak Inflow 17 Aug 06 0004
Peak Outflow 15.959 (cfs) Date/Time of Peak Outflow 17 Aug 06 0019
Total Inflow 6.32 (in) Peak Storage 0.75538(ac-ft)
Total Outflow 6.31 (in) Peak Elevation 525.03(ft)
rI
r?

CORBINTON COMMONS
EYC-06010
Stage-Storaf
Project Name:
Designed By:
Job Number:
Date:
Below NWSE-Pond #1
?e Function
Corbinton Commons
B. Ihnatolya, El
EYC-06010
11/8/2006

Contour
(feet)

Stage
€ (feet)
Contour
Area
(SF) Average
Contour
Area
? (SF) Incremental
Contour
Volume
(CF) Accumulated
Contour
Volume
(CF) Estimated
Stage
w/ S-S Fxn
(feet)
513.0 0.0 619
514.0 1.0 1297 958 958
958
1.05

516.0
3.0
2367
1832
3664 -------------------
4622
2.81
518.0 5.0 3738 3053 6105 10727 4.75
519.0 6.0 4565 4152 4152 14879 5.83
521.0 8.0 9449 7007 14014 28893 8.83
•
Storage vs. Stage
35000 _-
30000
1598
25000 Y = 888.73x
R2 = 0.9926
v 20000
0 15000
N
10000
5000
0
0.0 2.0 4.0 6.0 8.0 10.0
Stage (feet)
Ks = 888.73
b = 1.598
B. II NATOLYA, El
11/16/2006
0
•
Stage-Storage Function
Forebay-Pond #1
Project Name: Corbinton Commons
Designed By: B. Ilmatolya, El
Job Number: EYC-06010
Date: 11/8/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area i Area Volume Volume w/ S-S Fxn
(feet) (feet) (SF) i (SF) (CF) (CF) (feet)
514.0 0.0 439 y
516.0 2.0 92-21-1 681 1361 1361 2.01
518.0
519
0 -1 4.0
5
0 1549 1236 2471 3832 3.95
. . 1934 1742 1742 5574 5.05
•
Storage vs. Stage
6000-
y = 469.78x1 1279
5000 R2 = 0.9994
ai 4000
V
Sm 3000
0
y 2000
1000
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0
Stage (feet)
Ks = 469.78
b = 1.5279
CORBINTON COMMONS
EYC-06010
B. IHNATOLYA, El
11/16/2006

•
CORBINTON COMMONS
EYC-06010
CORBINTON COMMONS - POND #1
Volume Check-Pond #1
Per NCDENR "Stormwater Best Management Practices ", the forebay volume should equal about 20% of the total
basin volume.
A. Water Quality Pond - Below Normal Pool Volume
Volume = 28893 cf
B. Forebay Volume
Forebay Volume = 5574 cf
Forebay = 19.30
Impervious Area = `..: d acres
Drainage Area = 6.38 acres
0 in the Piedmont is as follows:
% Impervious = 63.9%
Total Below NP Volume 28893 cf
Surface Area 9449 sf
Average Depth = 3.06 ft
From the NCDENR Stormwater BMP Handbook (4/99), the required SA/DA ratio for 85% TSS Removal

3.0 3.06 4.0
Lower Boundary => 60.0 2.40 2.03
Site % impervious => 63.9 2.59 Z56 2.17
Upper Boundary => 70.0 2.88 2.40
Area Required = 7234 sf

Area Provided = 9449 sf YES
B. IHNATOLYA, El
11/16/2006
is
CORBINTON COMMONS
EYC-06010
Water Ouality Pond #1 Desian Sheet
Project Name: Corbinton Commons
Checked by: B. Ihnatolya, El
Job Number: EYC-06010
Date: 11/8/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet) (feet) (SF) (SF) (CF) (CF) (feet)

521.0 0.0 9449
522.0 1.0 10383 9916 9916 9916 1.01
524.0 3.0 12298 11341 22681 32597 2.95
526.0 5.00 14325 13312 26623 59220 5.06
•
•
Storage vs. Stage
70000
60000
50000 y = 9856.3x11081
C R2 = 0.9997
v 40000
m
a
c 30000
to
20000
10000
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0
Stage (feet)
Ks = 9856.3
b = 1.1061
Calculation of Runoff Volume required for storage
The runoff to the wetland for the 1" storm detention requirement is calculated using the SCS curve
number method. Impervious areas that directly enter the wetland are counted as Directly Connected
Impervious Areas (DCIAs). No infiltration calculation will be provided for these areas. Areas
not directly connected will be accounted for in a composite curve number.
From SCS Soils Survey map, predominant hydrologic soil type = B
Using basic SCS runoff methodology, with no adjustments made
to initial abstractions (0.2*S and 0.8*S).
Impervious Area, directly connected (DCIA) = 4.14 acres
@ CN = 98
Other areas draining to wetland (not DCIA) = 2.34 acres
@ CN = 65
B. IHNATOLYA
11/16/2006
1 OF 2
•
CORBINTON COMMONS
EYC-06010
Runoff from DCIAs =>
Precipitation amount = 0.5 inches
S = 0.204 inches (calculated)
Q* = 0.318 inches (calculated)
Runoff volume = 4777 CF
Runoff from non-connected areas =>
Precipitation amount = 0.5 inches
S = 5.385 inches (calculated)
Q* = 0.000 inches (calculated)
Runoff volume = 0 CF
B. IHNATOLYA
11/16/2006
Therefore, total runoff from precipitation in question = 4777 CF
This amount of runoff must be stored in the wetland above normal pool elevation,
and be released in a period of two (2) to five (5) days, by an inverted PVC
siphon, the invert end of which is set at permanent pool elevation.
Calculation of depth required for runoff storage pool (above normal pool)
Normal pool depth (above invert) = 0.00 feet
•
Storage provided at permanent pool depth =
Total storage required for normal + storage pool =
Stage (above invert) associated with this storage =
0 CF (calculated)
4777 CF
0.52 feet
1 Therefore, depth required above normal pool for storm storage = 0.52 feet
6.23 inches
Set crest of principal spillway at stage = 0.60 feet
and EL = 521.60 feet
At principal spillway crest, storm pool storage provided = 5602 CF
•
2OF2
CORBINTON COMMONS WATER QUALITY POND #1
EYC-06010
. Inverted Si phon Design Sheet
D siphon = 1.5 inches
No. siphons = 1
Ks = 9856.3
b = 1.1061
Cd siphon = 0.60
Normal Pool Elevation = 521.00 feet
Volume @ Normal Pool = 0 CF
Siphon Invert = 521.00 feet
WSEL @ 1" Runoff Volume = 521.60 feet

WSEL
(feet) Vol. Stored
W) Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
W) Incr. Time
(sec)
521.60 5602 0.043
521.55 5062 0.041 0.042 540 12800
521.49 4528 0.039 0.040 534 13377
521.44 3999 0.036 0.038 528 14057
521.39 3478 0.034 0.035 522 14878
521.34 2964 0.031 0.032 514 15898
521.28 2458 0.028 0.029 506 17217
521.23 1962 0.024 0.026 496 19024
521.18 1478 0.020 0.022 484 21744
521.13 1009 0.015 0.018 469 26629
521.07 560.2 0.007 0.011 448 40999
Drawdown Time = 2.28 days
By comparison, if calculated by the average head over the orifice (assuming
average head is half the total depth), the result would be:
Average driving head on orifice =
Orifice composite loss coefficient =
X-Sectional area of 1 - 1.5" inverted siphon =
Q = 0.0306 cfs
0.269 feet
0.600
0.012 ft2
Drawdown Time = Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.12 days
Conclusion : Use 1 - 1.5" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 0.5 " storm runoff, with a required time of about 2.28 days.
B. Ihnatolya, El
11/16/2006
0
•
C7
CORBINTON COMMONS WATER QUALITY POND #1 - 15" RCP
EYC-06010
Anti-Seep Collar Design Sheet
This sheet will, given the barrel length of interest and minimum seep collar
projection from the barrel, determine the number of anti-seep collars to place
along the barrel section, and the expected spacing of the collars.
Design Requirements =>
Anti-seep collars shall increase the flow path along the barrel by 15%.
Anti-seep collars shall be spaced a maximum of 14X the minimum collar projection
or 25 feet, whichever is less.
B. IHNATOLYA, El
11/16/2006
Anti-Seep Collar Design =>
WQP #
Flow Length Min. Calc'd # Max. # of Use
Pond along barrel Projection of collars Spacing collars to Spacing Spacing
ID (feet) (feet) required (feet) use (feet) OK?
1 - 15" RCP 45.0 1.70 1.99 23.8 2.00 15 YES
Note : If spacing to use is greater than the maximum spacing, add collars until the
spacing to use is equal to or less than the maximum spacing allowable for the collar
design. Anti-seep collars shall be used under the structural fill portions of all berms/dams
unless an approved drainage diaphragm is present at the downstream end of the barrel.
C7
•
•
CORBINTON COMMONS
EYC-06010
Input Data =_>
Square Riser/Barrel Anti-Flotation Calculation Sheet
Inside length of riser = 4.00 feet
Inside width of riser = 4.00 feet
Wall thickness of riser = 6.00 inches
Base thickness of riser = 8.00 inches
Base length of riser = 5.00 feet
Base width of riser = 5.00 feet
Inside height of Riser = 5.80 feet
Concrete unit weight = 142.0 PCF
OD of barrel exiting manhole = 21.00 inches
Size of drain pipe (if present) = 8.0 inches
Trash Rack water displacement = 38.00 CF
Concrete Present in Riser Structure =_>
Total amount of concrete:
Adjust for openings:
Base of Riser = 16.667 CF
Riser Walls = 52.200 CF
Opening for barrel = 1.203 CF
Opening for drain pipe = 0.175 CF
Total Concrete present, adjusted for openings =
Weight of concrete present =
Amount of water displaced by Riser Structure =_>
Displacement by concrete = 67.489 CF
Displacement by open air in riser = 92.800 CF
Displacement by trash rack = 38.000 CF
B. IHNATOLYA, El
11/20/2006
Note. NC' Produus lists um, wt. of
n?r:nhulc-4::r.;:;•etz ai :,2 ?t':?.
67.489 CF
9584 lbs
Total water displaced by riser/barrel structure = 198.289 CF
Weight of water displaced = 12373 lbs
Calculate amount of concrete to be added to riser =_>
Safety factor to use = 1.15 (:c:cA::n: yinti 1.15 0, lripl cr;
Must add = 4646 lbs concrete for buoyancy
Concrete unit weight for use = 142 PCF (note above observation for NCP concrete)
Buoyant weight of this concrete = 79.60 PCF
Buoyant, with safety factor applied = 69.22 PCF
•
Therefore, must add =
Standard based described above =
Therefore, base design must have =
67.118 CF of concrete
16.667 CF of concrete
83.785 CF of concrete
1 OF 2

CORBINTON COMMONS
EYC-06010
Calculate size of base for riser assembly =_>
Length =
Width =
Thickness =
Concrete Present =
Check validity of base as designed =_>
Base length = 8.00 feet
Base width = 8.00 feet
Base Thickness = 16.00 inches
CY of concrete total in base = 3.16 CY
Concrete unit weight in added base >= 142 PCF
8.000 feet
8.000 feet
16.0 inches
85.333 CF
Total Water Displaced = 266.956 CF
Total Concrete Present = 136.156 CF
Total Water Displaced = 16658 lbs
Total Concrete Present = 19334 lbs
•
•
Actual safety factor = 1.16
Results of design =_>
OK.
OK
B. IHNATOLYA, El
11/20/2006
2OF2
Corbinton Commons-Pond #1
Project # EYC-06010
VELOCITY DISSIPATOR DESIGN
Designed By: B. Ihnatolya
Velocity Dissipator - Pond #1
NRCD Land Quality Section
Pipe Design
Entering the following values will provide you with
the expected outlet velocity and depth of flow in a
pipe, assuming the Mannings roughness number is
constant over the entire length of the pipe.
flow Q in cfs : 14.628 Flow depth (ft) = 1.25
slope S in %: 0.794 Outlet velocity (fps) = 11.920
pipe diameter D in in.: 15
Manning number n : 0.013
NRCD Land Quality Section
NYDOT Dissipator Design Results
•
Pipe diameter (ft) 1.25
Outlet velocity (fps) 11.92
Apron length (ft) 7.5
AVG DIAM STONE THICKNESS
(inches) CLASS (inches)
-------- ----- -
3 A --------
9
»6 B 22a
13 Bor1 22
23 2 27
Width Calculation
WIDTH = La + Do
WIDTH=7.5+1.25
WIDTH = 8.75 FF.F.T
CONCLUSION
Use 13" DIA NCDOT Class `B' Rip Rap
8'L x 9'W x 22"Thick
0
r?
U
WATER QUALITY POND #2 FINAL DESIGN
CALCULATIONS
.7
•
CORBINTON COMMONS
EYC-06010
0009-T9E (BT B) ..•,,,"•,•,, &'IIvma co aNodE
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d\:X
CORBINTON COMMONS
EYC-06010
StSge-StOra4
Project Name:
Designer:
Job Number:
Date:
•
to Function
Corbinton Commons
B. Ihnatolya, El
EYC-06010
11/8/2006
B. IHNATOLYA, EI
11/16/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet) (feet) (SR (SR (CF) (CFl (feetl
524.0 0.0 25199
526.0 2.0 301.14 27657 55313 55313 2.01
528.0 4.0 35235 32675 65349 120662 3.96
530.0 6.0 4062$ 37932 75863 196525 6.04
Storage vs. Stage
250000
200000--
y = 24791x"""
LL 150000 R2
= 0.9997
m
m
0 100000
y
50000
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
Stage (feet)
Ks = 24791
b = 1.1509
•
CORBINTON COMMONS
EYC-06010
• _> Stage - Storage Function
Ks = 24791
b= 1. 1509
Z0= 524
Elevation
0
524 0 0.000
524.2 3889 0.089
524.4 _8636_ 07198
524.6 13771 0.316
524.8 19176 0.440
525 24791 0.569

525.2
525.4
30579
36515 _
0.702
0.838
525.6 42581 0.978
525.8 48763 1.119
526 ?
526.2 55049
61431 1.264
1.410
526.4 67901 1.559
526.6 74454 1.709
5_26.8 81083 1.861
527 _
87784 2.015
527.2 94552 2.171
527.4 101385 2.327
527.6
527.8 108279
115230 2.486
2.645
528 122238 2.806
528.2
_ 129298 2.968
_528.4
_
-
-- 136409 3.132
28.6
5
2876 143569 3.296
528.8 150777 3.461
529 158030 3.628
529.2
-
-
- 165326 3.795
4
324. 172666 3.964
529.6 180046 4.133
_ 529.8 187466 4.304
530 194925 s 4.475
B. IHNATOLYA, El
11/16/2006

Type.... Outlet Input Data Page 1.01
Name.... Pond #2
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 524.00 ft
Increment = .20 ft
Max. Elev.= 530.00 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
Orifice-Circular OR ---> TW 524.000 530.000
Inlet Box RI ---> BA 528.000 530.000
Culvert-Circular BA ---> TW 518.500 530.000
TW SETUP, DS Channel
C7
1]
SIN: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 5:53 PM Date: 11/16/2006
Type.... Outlet Input Data
Name.... Pond #2
l?
u
Page 1.02
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = OR
Structure Type = Orifice-Circular
------------------------------------
# of openings = 1
Invert Elev. = 524.00 ft
Diameter = .1667 ft
Orifice Coeff. _ .600
Structure ID = RI
Structure Type
-------- = Inlet Box
---------
# of Openings ------------
= 1 -------
Invert Elev. = 528.00 ft
Orifice Area = 25.0000 sq.ft
Orifice Coeff. _ .600
Weir Length 20.00 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
r?
•
SIN: 6217012070C3
PondPack Ver. 8.0058
The John R. McAdams Company
Time: 5:53 PM
Date: 11/16/2006
r?
Type.... Outlet Input Data
Name.... Pond #2
Page 1.03
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = BA
Structure Type
------------------ = Culvert-Circular
-------------

No. Barrels
= 1 -----
Barrel Diameter = 2.0000 ft
Upstream Invert = 518.50 ft
Dnstream Invert = 518.00 ft
Horiz. Length = 82.00 ft
Barrel Length = 82.00 ft
Barrel Slope = .00610 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .012411
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) 1.157
T2 ratio (HW/D) 1.304
Slope Factor = -.500
C7
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 = 520.81 ft ---> Flow = 15.55 cfs
At T2 Elev = 521.11 ft ---> Flow = 17.77 cfs
•
SIN: 6217012070C3
PondPack Ver. 8.0058
The John R. McAdams Company
Time: 5:53 PM Date: 11/16/2006
•
Type.... Outlet Input Data
Name.... Pond #2
Page 1.04
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
OUTLET STRUCTURE INPUT DATA
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
•
•
SIN: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 5:53 PM Date: 11/16/2006
1
C7
11
Type.... Composite Rating Curve
Name.... Pond #2
Page 1.11
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON_COMMONS.PPW
Title... Project Date: 11/9/2006
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
WS Elev, Total Q
Elev. Q
ft
-- cfs
------
524.00 -------
.00
524.20 .04
524.40 .06
524.60 .08
524.80 .09
525.00 .10
525.20 .11
525.40 .12
525.60 .13
525.80 .14
526.00 .15
526.20 .15
526.40 .16
526.60 .17
526.80 .17
527.00 .18
527.20 .19
527.40 .19
527.60 .20
527.80 .20
528.00 .21
528.20 5.58
528.40 15.40
528.60 28.11
528.80 43.16
529.00 47.90
529.20 48.43
529.40 48.95
529.60 49.46
529.80 49.96
530.00 50.47
SIN: 621701207003
PondPack Ver. 8.0058
***** COMPOSITE OUTFLOW SUMMARY ****
-------- Converge
TW Elev Error
ft +/-ft
-------- -----
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Notes
-------------------------
Contributing Structures
(no Q: OR,RI,BA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RI,BA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RI,BA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RI,BA)
OR (no Q: RI,BA)
OR (no Q: RI,BA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RIBA)
OR (no Q: RI,BA)
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
OR,RI,BA
The John R. McAdams Company
Time: 5:52 PM Date: 11/16/2006
HMS * Summary of Results for Pond #2
•
Project : EYC-06010
Start of Run : 16Aug06 1200
End of Run : 17Aug06 1200
Execution Time : 16Nov06 1800
Run Name : 10-Year Post
•
Basin Model : Post-Development
met. Model 10-Year Storm
Control Specs : 1-Min dT
Computed Results
Peak Inflow 72.923 (cfs)
Peak Outflow 3.2954 (cfs)
Total Inflow 3.22 (in)
Total Outflow 0.99 (in)
Date/Time of Peak Inflow 17 Aug 06 0004
Date/Time of Peak Outflow 17 Aug 06 0235
Peak Storage 2.8991(ac-ft)
Peak Elevation 528.11(ft)
J
HMS * Summary of Results for Pond #2
•
Project : EYC-06010
Start of Run 16Aug06 1200
End of Run 17Aug06 1200
Execution Time 16Nov06 1801
Run Name : 100-Year Post
0
Basin Model : Post-Development
Met. Model 100-Year Storm
Control Specs : 1-Min dT
Computed Results
Peak Inflow 114.47 (cfs)
Peak Outflow 40.216 (cfs)
Total Inflow 5.61 (in)
Total Outflow 3.37 (in)
Date/Time of Peak Inflow : 17 Aug 06 0004
Date/Time of Peak Outflow : 17 Aug 06 0017
Peak Storage 3.4287(ac-ft)
Peak Elevation 528.76(ft)

•
•
CORBINTON COMMONS
EYC-06010
Stage - Storage Function
Ks= 24791
b= 1.15119
Zo = 524
Elevation
_...._.._.__..'_ __.,......._?._...... _...n? _. _..
528_ 122238 1806
528.2 129298 2.968
528.4 136409 3.132
528.6 143569 3.296
528.8 150777 3.461
529 158030 ' 3.628
529.2 165326 3.795
529.4 172666 3.964
529.6 180046 4.133
529.8 187466 4.304
530 € 194925 1 4.475
B. IRNATOLYA, El
11/16/2006
100-YR S-S Function-Clogged Siphon Condition
Elevation
528.0 0 0.000
528.2 7060 0.162
528.4 ? 14172 0.325
528.6 21332 0.490

528.8 ? 28539 0.655
529.0
.___ ....... ..... 35792
..... 0.822
52_9._2
.
__ 43089 1
_' 0.989
529 4 50428 1.158
529.6 ?57808 1.327
529.8 65229 1.497
530,0 72nxx 1.669
•
Type.... Composite Rating Curve Page 1.07
Name.... Pond #2-WC
File.... X:\Projects\EYC\EYC-06010\Storm\Construction Drawings\CORBINTON
COMMONS.PPW
Title... Project Date: 11/9/2006 _
Project Engineer: B. Ihnatolya, EI
Project Title: Corbinton Commons
Project Comments:
Clov-yR

***** COMPOSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Notes
-------- -------- -------- Converge
-----------------
--------
Elev. Q TW Elev Error
ft
-------- cfs ft +/-ft
------- - Contributing Structures

528.00 ------- -----
.00 Free Outfall ------------------
(no Q: RIBA) --------
528.20 5.37 Free Outfall RI,BA
528.40 15.18 Free Outfall RI,BA
528.60 27.88 Free Outfall RIBA
528.80 42.93 Free Outfall RIBA
529.00 47.67 Free Outfall RIBA
529.20 48.19 Free Outfall RIBA
529.40 48.70 Free Outfall RIBA
529.60 49.21 Free Outfall RIBA
529.80 49.71 Free Outfall RIBA
530.00 50.21 Free Outfall RI,BA
C7
C7
SIN: 6217012070C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 5:57 PM Date: 11/16/2006
HMS * Summary of Results for Pond #2
Project : EYC-06010 Run Name : 100-YR-WC
Start of Run 16Aug06 1200 Basin Model Worst Case
End of Run 17Aug06 1200 Met. Model 100-Year Storm
Execution Time 16Nov06 1803 Control Specs 1-Min dT
Computed Results
Peak Inflow 114.47 (cfs) Date/Time of Peak Inflow : 17 Aug 06 0004
Peak Outflow 49.442 (cfs) Date/Time of Peak Outflow : 17 Aug 06 0014
Total Inflow 5.61 (in) Peak Storage : 1.4060(ac-ft)
Total Outflow 5.59 (in) Peak Elevation : 529.69(ft)
•
C,
F-1
Stage-Storage Function
Below NWSE-Pond #2
Project Name: Corbinton Commons
Designed By: B. Ilmatolya, El
Job Number: EYC-06010
Date: 11/8/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet) € (feet) (SF) (SF) (CF) (CF) (feet)
518.0 0.0 9343
520.0 2.0 12159 10751 21502 21502 2.03
52276 4.0 15359 13759 27518 49020 185
524.0 6.0 25199 20279 40558 89578 6.15
•
Storage vs. Stage
100000

90000 ---
80000 y = 8651.2x' 287
70000 R2 = 0.9963
u 60000
mrn 50000
a
`
o
40000
N
30000
20000
10000
0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
Stage (feet)
Ks = 8651.2
b = 1.287
CORBINTON COMMONS
EYC-06010
B. IHNATOLYA, El
11/16/2006
0
•
State-Storage Function
Forebay-Pond #2
Project Name: Corbinton Commons
Designed By: B. Ihnatolya, EI
Job Number: EYC-06010
Date: 11/8/2006
I Average Incremental Accumulated Estimated
Contour i Contour Contour Contour Stage
Contour Stage Area I Area Volume Volume w/ S-S Fxn
(feet) (feet) (SF) (SF) (CF) (CF) (feet)
518.0 _0.0 3370
520.0 2.0 434_4_ 1 3857 7714 7714 2.00
522.0 4.0 5417 4881 9761 17475 4.00
•
Storage vs. Stage
20000
18000
16000 y = 3405.2x1197
14000 R2 = 1
V 12000
w 10000
0 8000
N
6000
4000
2000
0
0.0 1.0 2.0 3.0 4.0 5.0
Stage (feet)
Ks = 3405.2
b = 1.1797
CORBINTON COMMONS
EYC-06010
B. IHNATOLYA, El
11/16/2006

CORBINTON COMMONS Volume Check-Pond #2
EYC-06010
CORBINTON COMMONS - POND #2
Per NCDENR "Stormwater Best Management Practices ", the forebay volume should equal about 20% of the total
basin volume.
A. Water Quality Pond - Below Normal Pool Volume
Volume = 89578 cf
B. Forebay Volume
Forebay Volume = 17475 cf
Forebay = 20%
Impervious Area = 7.17 acres
Drainage Area = 3514 acres
% Impervious = 48.0%
•
Total Below NP Volume 89578 cf
Surface Area 25199 sf
Average Depth = 3.55 ft
From the NCDENR Stormwater BMP Handbook (4/99), the required SA/DA ratio for 85% TSS Removal
in the Piedmont is as follows:
3.0 3.55 4.0
Lower Boundary => 40.0 1.73 1.43
Site % impervious => 48.0 1.99 1.81 1.67
Upper Boundary => 50.0 2.06 1.73
Area Required = 11969 sf
Area Provided = 25199 sf YES
B. 1HNATOLYA, El
11/16/2006
•
•
r]
Ks = 24791
b = 1.1509
Calculation of Runoff Volume required for storage
The runoff to the wetland for the 1" storm detention requirement is calculated using the SCS curve
number method. Impervious areas that directly enter the wetland are counted as Directly Connected
Impervious Areas (DCIAs). No infiltration calculation will be provided for these areas. Areas
not directly connected will be accounted for in a composite curve number.
From SCS Soils Survey map, predominant hydrologic soil type = B
•
CORBINTON COMMONS
EYC-06010
Water Ouality Pond #2 Desiin Sheet
Project Name: Corbinton Commons
Checked by: B. Ihnatolya, El
Job Number: EYC-06010
Date: 11/8/2006
B. IHNATOLYA, El
11/16/2006
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet) (feet) (SF) (SF) (CF) (CF) (feet)
524.0 0.0 25199
526.0 2.0 30114 27657 55313 55313 2.01
528.0 4.0 35235 32675 65349 120662 3.96
530.0 6.00 40628 37932 75863 196525 6.04
Storage vs. Stage
250000 -- -- -
200000--
y = 24791x' •'eos
150000 R2 = 0.9997
m
m
`0 100000
N
50000
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
Stage (feet)
Using basic SCS runoff methodology, with no adjustments made
to initial abstractions (0.2*S and 0.8*S).
Impervious Area, directly connected (DCIA) =
@CN=
7.27 acres
98
Other areas draining to wetland (not DCIA) =
@CN=
7.87 acres
64
I OF 2
r
?J
CORBINTON COMMONS
EYC-06010
Runoff from DCIAs =>
Precipitation amount = 0.5 inches
S = 0.204 inches (calculated)
Q* = 0.318 inches (calculated)
Runoff volume = 8389 CF
Runoff from non-connected areas =>
Precipitation amount = 0.5 inches
S = 5.625 inches (calculated)
Q* = 0.000 inches (calculated)
Runoff volume = 0 CF
B. IHNATOLYA, El
11/16/2006
Therefore, total runoff from precipitation in question = 8389 CF
This amount of runoff must be stored in the wetland above normal pool elevation,
and be released in a period of two (2) to five (5) days, by an inverted PVC
siphon, the invert end of which is set at permanent pool elevation.
Calculation of depth required for runoff storage pool (above normal pool)
Normal pool depth (above invert) = 0.00 feet
1I 1'
u
Storage provided at permanent pool depth = 0 CF (calculated)
Total storage required for normal + storage pool = 8389 CF
Stage (above invert) associated with this storage = 0.39 feet
Therefore, depth required above normal pool for storm storage = 0.39 feet
4.68 inches
Set crest of principal spillway at stage = 0.40 feet
and EL = 524.40 feet
At principal spillway crest, storm pool storage provided = 8636 CF
•
2OF2
CORBINTON COMMONS WATER QUALITY POND #2
EYC-06010
• Inverted Sip hon Design Sheet
D siphon = 2 inches
No. siphons = 1
Ks = 24791
b = 1.1509
Cd siphon = 0.60
Normal Pool Elevation = 524.00 feet
Volume @ Normal Pool = 0 CF
Siphon Invert = 524.00 feet
WSEL @ 0.5" Runoff Volume = 524.40 feet
•
WSEL
(feet) Vol. Stored
W) Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
(cf) Incr. Time
(sec)
524.40 8636 0.059
524.37 7782 0.056 0.057 8.54 14883
524.33 6941 0.052 0.054 842 15603
524.30 6112 0.048 0.050 828 16475
524.26 5298 0.044 0.046 814 17564
524.23 4500 0.040 0.042 798 18984
524.19 3721 0.035 0.037 780 20955
524,16 2962 0.028 0.031 759 24219
524.12 2228 0.019 0.024 734 31011
524.09 1525 0.012 0.016 703 45190
524.05 863.6 0.006 0.009 662 76041
Drawdown Time = 3.25 days
By comparison, if calculated by the average head over the orifice (assuming
average head is half the total depth), the result would be:
Average driving head on orifice = 0.158 feet
Orifice composite loss coefficient = 0.600
X-Sectional area of 1 - 2" inverted siphon = 0.022 ft2
Q= 0.0418 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.39 da s
Conclusion : Use 1 - 2.0" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 0.5 " storm runoff, with a required time of about 3.25 days.
B. Ihnatolya, El
11/20/2006
•
CORBINTON COMMONS WATER QUALITY POND #2 -15" RCP B. IHNATOLYA, EI
EYC-06010 11/16/2006
• Anti-Seep Collar Design Sheet
This sheet will, given the barrel length of interest and minimum seep collar
projection from the barrel, determine the number of anti-seep collars to place
along the barrel section, and the expected spacing of the collars.
Design Requirements =>
Anti-seep collars shall increase the flow path along the barrel by 15%.
Anti-seep collars shall be spaced a maximum of 14X the minimum collar projection
or 25 feet, whichever is less.
Anti-Seep Collar Design =>
WQP #

Flow Length Min. Calc'd # Max. # of Use
Pond along barrel Projection of collars Spacing collars to Spacing Spacing
ID (feet) (feet) required (feet) use (feet) OK?
2 - 15" RCP 60.0 2.25 2.00 25 2.00 20 YES
Note : If spacing to use is greater than the maximum spacing, add collars until the
spacing to use is equal to or less than the maximum spacing allowable for the collar
design. Anti-seep collars shall be used under the structural fill portions of all berms/dams
unless an approved drainage diaphragm is present at the downstream end of the barrel.
0
U
•
CORBINTON COMMONS
EYC-06010
Input Data =_>
Square Riser/Barrel Anti-Flotation Calculation Sheet
Inside length of riser = 5.00 feet
Inside width of riser = 5.00 feet
Wall thickness of riser = 6.00 inches
Base thickness of riser = 8.00 inches
Base length of riser = 6.00 feet
Base width of riser = 6.00 feet
Inside height of Riser = 9.50 feet
Concrete unit weight = 142.0 PCF
OD of barrel exiting manhole = 31.50 inches
Size of drain pipe (if present) = 8.0 inches
Trash Rack water displacement = 61.74 CF
Concrete Present in Riser Structure =_>
Total amount of concrete:
Adjust for openings:
Base of Riser = 24.000 CF
Riser Walls = 104.500 CF
Opening for barrel = 2.706 CF
Opening for drain pipe = 0.175 CF
B. IHNATOLYA, El
11/20/2006
Note- NCF:.xiucts iisl? ur _ w :- :;1.
33mmbMe cxxicuate at 142 PC. F.
Total Concrete present, adjusted for openings = 125.620 CF
Weight of concrete present = 17838 lbs
Amount of water displaced by Riser Structure =_>
Displacement by concrete = 125.620 CF
Displacement by open air in riser = 237.500 CF
Displacement by trash rack = 61.740 CF
Total water displaced by riser/barrel structure = 424.860 CF
Weight of water displaced = 26511 lbs
Calculate amount of concrete to be added to riser =_>
Safety factor to use = 1.15 (: co-nmenct 1.15 :n itiriie-0
Must add = 12650 lbs concrete for buoyancy
Concrete unit weight for use = 142 PCF (note above observation for NCP concrete)
Buoyant weight of this concrete = 79.60 PCF
Buoyant, with safety factor applied = 69.22 PCF
Therefore, must add = 182.757 CF of concrete
•
Standard based described above = 24.000 CF of concrete
Therefore, base design must have = 206.757 CF of concrete
1 OF 2
•
CORBINTON COMMONS
EYC-06010
Calculate size of base for riser assembly =_>
Length = 8.000 feet
Width = 8.000 feet
Thickness = 39.0 inches
Concrete Present = 208.000 CF
Check validity of base as designed =_>
OK
Total Water Displaced = 608.860 CF
Total Concrete Present = 309.620 CF
Total Water Displaced = 37993 IN
Total Concrete Present = 43966 IN
•
•
Actual safetyfactor = 1.16
Results of design =_>
OK
B. IHNATOLYA, El
11/20/2006
Base length = 8.00 feet
Base width = 8.00 feet
Base Thickness = 39.00 inches
CY of concrete total in base = 7.70 CY
Concrete unit weight in added base >= 142 PCF
2OF2
Corbinton Commons-Pond #2
Project # EYC-06010
VELOCITY DISSIPATOR DESIGN
• Designed By: B. Ihnatolya
Velocity Dissipator - Pond #2
NRCD Land Quality Section
Pipe Design
Entering the following values will provide you with
the expected outlet velocity and depth of flow in a
pipe, assuming the Mannings roughness number is
constant over the entire length of the pipe.
flow Q in cfs : 3.295 Flow depth (ft) = 0.59
slope S in % : 0.610 Outlet velocity (fps) = 4.306
pipe diameter D in in.: 24
Manning number n : 0.013
NRCD Land Quality Section
NYDOT Dissipator Design Results
C7
Pipe diameter (ft) 2.00
Outlet velocity (fps) 4.31
Apron length (ft) 8.00
AVG DIAM STONE THICKNESS
(inches) CLASS
-------- ----- (inches)
--
»3 A -------
9«
6 B 22
13 B or 1 22
23 2 27
Width Calculation
WIDTH = La + Do
WIDTH = 8.0 + 2.0
WIDTH = 1(1 /1 Fri FT
CONCLUSION
Use 13" DIA NCDOT Class `A' Rip Rap
8'L x 101W x 9"Thick
is