20051882 Ver 4_Stormwater Info_20070702

Since 1979
THE JOHN R. McADAMS COMPANY, INC.
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HIGHLAND CREEK -PHASES 2 & 4
RALEIGH, NORTH CAROLINA
FINAL DESIGN OF STORMWATER MANAGEMENT
FACILITIES #1, #2, #7, & #10
CTX-06070
May 2007
Revised: June 2007
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
Jonathan A. Aldridge, EI
Associate Project Engineer
Brandon R. Finch, PE
Sr. Stormwater Project Manager
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Comprehensive Land Development Design Services
www.johnrmcadams.com We help our clients succeed.

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HIGHLAND CREEK -PHASES 2 & 4
Final Design of stormwater Management Facilities #1, #2, #7, & #10
General Description
Located on Highway 401, just east of its crossing with the Neuse River and west of its
intersection with Forestville Road in Raleigh, North Carolina, is the proposed mixed-use
residential development currently known as Highland Creek. Proposed development on
this site will consist of the construction of both single and multi-family residential areas,
along with associated streets, parking, utilities, and other infrastructure.
The proposed development is located within the Neuse River basin and will be subject to
the stormwater management requirements set forth in Section 10, Chapter 9 of the City of
Raleigh regulations. Per City of Raleigh regulations, stormwater management on this site
shall address two primary issues: (1) peak discharge rates and (2) water quality
management.
1. The peak stormwater runoff leaving any site for the two year and ten year storms
shall be no greater for post-development conditions than pre-development
conditions. The same methodologies used to calculate stormwater runoff must be
used for both pre-development and post-development conditions (Section 10-
9023a).
2. No development nor any expansion of an existing development, use, facility,
building, structure, nor any new or expanded vehicular surface area shall
contribute a nitrogen export load exceeding three and six tenths (3.6) pounds per
acre per year. Developers shall have the option of offsetting their nitrogen export
• load limitations by paying monies to the North Carolina Wetland Restoration
Fund. For residential development, aone-time offset payment of three hundred
thirty dollars ($330.00) per pound may be paid to the North Carolina Wetland
Restoration Fund to bring the nitrogen load from six (6) pounds per acre per year
to three and six tenths (3.6) pounds per acre per year. Residential developments
which exceed nitrogen export loads of six (6) pounds per acre per year and other
developments which exceed ten (10) pounds per acre per year must install City
approved stormwater control measures to reduce the nitrogen export load of their
development to the applicable six (6) pounds per acre per year or ten (10) pounds
per acre per year limitation to become eligible for payment offsets (Section 10-
9022a-c).
Please note that residential development is defined in Section 10-9002 as any lot
devoted to single family or duplex land use.
This report contains calculations detailing the expected stormwater impacts as a result of
the proposed development, along with designs of stormwater management facilities that
will be used to mitigate the impacts. Please refer to the appropriate section of this report
for additional information.

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Calculation Methodolo~y
• 1. Rainfall data for the Raleigh, NC region is derived from USWB Technical Paper
No. 40 and NOAA Hydro-35. This data was used to generate adepth-duration-
frequency (DDF) table describing rainfall depth versus time for varying return
penods. These rainfall depths were then input into the meteorological model
within HEC-HMS for peak flow rate calculations. Please reference the
precipitation data section within this report for additional information.
2. The 1/3 Probable Maximum Precipitation (1/3 PMP) was entered into HEC-HMS
as a "User Hyetograph" with the 6-hour distribution presented in The Soil
Conservation Service's Technical Release No. 60 (Six Hour Design Storm
Distribution). The total rainfall depth modeled in 10 inches.
3. Using maps contained within the Wake County Soil Survey, the on- and off-site
soils were determined to range from hydrologic soil group (HSG) `B' soils to
HSG `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,
care was taken when selecting the appropriate Soil Conservation Service Curve
Number (SCS CN).
Within each sub-basin, an approximate proportion of each soil group was
determined using NRCS Soil Survey Maps. Once an approximate proportion was
determined, a composite SCS CN was computed for each cover condition. For
example, the pre-development condition of Sub-basin #5 consists of
approximately 50% HSG `B' soils and 50% HSG `D' soils. Therefore, for the
open area cover condition, the composite SCS CN is computed as follows
• (assuming good condition):
Composite Open SCS CN = (0. S *61) + (0.5 * 80) = 71
This type of calculation was done for each of the studied sub-basins in the pre-
and post-development condition in an effort to accurately account for the
difference in runoff between HSG `B' soils and HSG `D' soils.
4. The post-development times of concentration to each stormwater facility are
assumed to be 5 minutes in the post-development condition.
5. The on- and off-site topography used in the analysis is from two different sources.
They are as follows:
a. The on-site topography is from a recent aerial survey provided to The John
R. McAdams Company, Inc.
b. The remainder of the existing topography is from LIDAR topography
obtained by The John R. McAdams Company, Inc. from a web site run by
the N.C. Floodplain Mapping Program. Please note that the vertical datum
for this topography is based on NAVD 88.
The two sets of data mentioned above were "spliced" together to construct the
existing topography used in the analysis. Please refer to the pre- and post-
development watershed maps for more information.
•

6. HEC-HMS Version 2.2.2, by the U.S. Army Corps of Engineers, is used to
• generate pre- and post-development peak flow rates and model the proposed
stormwater management facilities.
7. Pondpack Version 8.0, by Haestad Methods, is used to generate the stage-
discharge rating curves for the proposed stormwater management facilities. These
rating curves are then input into HEC-HMS for routing calculations.
8. The stage-discharge rating curve, stage-storage rating curve, and stage-storage
function for the proposed wetlands were all generated outside of HEC-HMS and
then input into HEC-HMS.
9. Water quality sizing calculations were performed in accordance with the N.C.
Stormwater Best Management Practices manual (NCDENR April 1999). The
normal pool surface area of the wetland facilities was sized using a 3.0 ft average
depth and the appropriate SA/DA ratio. A temporary storage pool for runoff
resulting from the 1.0" storm is provided in all facilities, to be drawn down in 2 to
5 days using an inverted siphon.
10. For 100-year storm routing calculations, a "worst case condition" was modeled in
order to insure the proposed facilities would safely pass the 100-year storm event.
The assumptions 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 siphon 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 inverted siphon has an opportunity to draw down the storage
pool between NWSE and the riser crest elevation.
2. A minimum of approximately 0.5-ft of freeboard was provided between
the peak elevation during the "worst case" scenario and the top of the dam
for each facility.
11. Nitrogen export calculations are computed using Method 2 from the City of
Raleigh Storm Drainage Manual. This method uses known footprint areas of
wooded, open, and impervious surfaces.
12. A velocity dissipater is provided at the principal spillway outlets to prevent
erosion and scour in these area. The dissipaters are constructed using rip rap,
underlain with a woven geotextile filter fabric. The filter fabric is used to
minimize the loss of soil particles beneath the rip rap apron. The dissipaters are
sized for the 50-year storm event using the NYDOT method. It is a permanent
feature of the outlet structures.
13. To guard against dam failure due to the buoyant forces caused by the riser-barrel
outlet structures, anti-flotation calculations were performed. These calculations
consisted of determining the amount of concrete that is required to anchor the
outlet structures down and prevent them from floating. In addition, the pre-cast
riser sections are to be tied together to prevent separation caused by buoyant
forces. These calculations contain a minimum 15% safety factor.
• 14. Development proposed on this site consists of both single and multi-family
residential areas. Therefore, in order to compute the maximum allowable TN-

export from this site without physical TN-removal, a composite average was
• computed for the entire site using defined areas of multi-family use and defined
areas of single-family use for the phases that have been developed (1, 2, and 4).
The computation for the composite TN-export average is as follows:
Total Site Area = 176.05 acres
Single-Family Area = 94.75 acres
Multi-Family Area = 49.52 acres
Stream Buffer /Common R/W Area = 31.78 acres
Since 66% of the residential area is single-family, and 34% multi-family,
the 31.78 acres of unused common space was allotted accordingly (20.87
acres to single-family, 10.91 acres to multi-family). This means that the
total area attributed to multi-family was 60.43 acres and 115.62 acres were
attributed to single-family.
Therefore, Maw Allowable TN-Export w/o Physical Removal =
[(115.62 ac * 6.0 lbs/ac/yr) +(60.43 ac * 10.0 lbs/ac/yr)J / 176.05 ac =
7.37 lbs/ac/yr
Discussion of Results
Sub-basin 1
• As shown in the HEC-HMS output tables, there is a significant increase (between pre-
and post-development) for the on-site areas of Sub-basin 1. However, this sub-basin
drains to an existing 18-inch culvert crossing located immediately adjacent to the property
line for Highland Creek. For this reason, the point of analysis will shift to the existing
18-inch culvert crossing. This issue has been previously discussed and agreed upon with
representatives from the City of Raleigh. As shown in the Summary of Results table, the
maximum predicted increase in peak flow rate at the existing culvert crossing is 9.4%.
This is an acceptable increase (without on-site detention) since the increase is less than
10%
Sub-basin 4C
As shown in the Summary of Results table, there is a significant increase (in percentage
only) for the 2-year storm of 0.3 cfs to 0.6 cfs. Also, there is a predicted increase of 8% in
the 10-year storm (1.2 cfs to 1.3 cfs). Since the 10-year storm is less than the allowable
10% increase and the 2-year increase is 0.3 cfs, it is the opinion of the design engineer
that the 2-year increase is negligible and can be ignored. For this reason, on-site detention
facilities are not provided in this sub-basin.
Sub-basins 4 & 5
There are three stormwater management facilities proposed for these sub-basins. These
facilities will function as "dual-purposed facilities" by providing reduction in TN-export
and by providing detention such that the pre-development peak flow rates are no greater
than post-development peak flow rates in the 2- and 10-year design storm events. Please
• refer to the Summary of Results table for additional information.

Junctions 3 & 4
• There are five total stormwater management facilities proposed /built for the sub-basins
that contribute to these analysis points (4 of which have been built as part of Phase 1 and
Phase 1B of the overall development). These facilities will function as "dual-purposed
facilities" by providing reduction in TN-export and by providing detention such that the
pre-development peak flow rates are no greater than post-development peak flow rates in
the 2- and 10-year design storm events. Please refer to the Summary of Results table for
additional information.
Conclusion
If the development on this tract is built as proposed within this report, then the
requirements set forth in Section 10, Chapter 9 of the City of Raleigh regulations will be
met with the proposed stormwater management facilities. 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.
•
.7

HIGHLAND CREEK SUMMARY OF RESULTS B.R. FINCH, PE
CTX-06070 6/29/2007
•
_> RELEASE RATE MANAGEMENT RESULTS
JUNCTION #3
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 191.9 170.6 - 11.1
10-Year 606.0 561.5 -7.3%
JUNCTION #4
Return Period Pre-Development
[cfs] Post-Dev [Design]
[cfs] % Increase
[%] Post-Dev [Actual]
[cfs] % Increase
[%]
2-Year 227.7 216.5 -4.9% 210.3 -7.6%
10-Year 719.1 686.5 -4.5% 679.4 -5.5%
SUB-BASIN #1- ON- & OFFSITE TO EXISTING CULVERT CROSSING
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 8.5 9.3 9.4%
10-Year 19.2 18.8 -2.1
SUB-BASIN #2
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 2.6 2.6 0.0%
10-Year 10.3 10.3 0.0%
SUB-BASIN #4A
•
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 6.0 4.7 -21.7%
10-Year 23.3 22.4 -3.9%
SUB-BASIN #4B
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 1.6 0.3 -81.3%
10-Year 6.6 0.8 -87.9%
SUB-BASIN #4C
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 0.3 0.6 100.0%
10-Year 1.2 1.2 0.0%
SUB-BASIN #5
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 37.4 21.3 -43.0%
10-Year 85.2 57.7 -32.3%
SUB-BASIN #S
Return Period Pre-Development
[cfs] Post-Development
[cfs] % Increase
[%]
2-Year 3.5 0.2 -94.3%
10-Year 9.4 0.6 -93.6%
•

HIGHLAND CREEK SUMMARY OF RESULTS B.R. FINCH, PE
CTX-06070 6/29/2007
• _> ROUTING RESULTS
SWMF I (Subbasin #5):
Top of Dam =
283.00 ft
Return Period Inflow
[cfs] Outflow
[cfs] Max. WSE
[ft] Freeboard
[ft]
2-Year 84.7 0.5 279.87 3.13
10-Year 124.9 20.4 280.47 2.53
50-Year 168.7 83.8 281.25 1.75
1/3 PMP 160.5 102.3 282.32 0.68
SWMF 2 (Subbasin #S):
Top of Dam = 285.00
Return Period Inflow
[cfs] Outflow
[cfs] Max. WSE
[ft] Freeboard
[ft]
2-Year 48.6 0.5 282.61 2.39
10-Year 69.7 15.2 283.00 2.00
50-Year 92.8 58.1 283.58 1.42
1/3 PMP 88.2 69.3 284.10 0.90
SWMF 7 (Subbasin #3C):
Top of Dam = 272.00 ft
•
Return Period Inflow
[cfs] Outflow
[cfs] Max. WSE
[ft] Freeboard
[ft]
2-Year 79.8 22.3 268.51 3.49
10-Year 135.2 85.4 269.32 2.68
100-Year Worst Case 221.8 99.6 270.89 1.1 ]
SWMF 10 (Subbasin #4):
Top of Dam = 280.00 ft
Return Period Inflow
[cfs] Outflow
[cfs] Max. WSE
[ft] Freeboard
[ft]
2-Year 85.1 0.5 276.39 3.61
10-Year 133.1 18.8 277.05 2.95
50-Year 185.4 74.3 277.89 2.11
1/3 PMP 178.6 86.4 279.44 0.56
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1 PRECIPITATION DATA
2 WATERSHED SOILS DATA
PRE-DEVELOPMENT
3 HYDROLOGIC CALCULATIONS
POST-DEVELOPMENT
4, HYDROLOGIC CALCULATIONS
FINAL DESIGN OF STORMWATER
5 MANAGEMENT FACILITY #1
FINAL DESIGN OF STORMWATER
6 MANAGEMENT FACILITY #2
FINAL DESIGN OF STORMWATER
'7 MANAGEMENT FACILITY #7
FINAL DESIGN OF STORMWATER
g MANAGEMENT FACILITY #10
700-YEAR STORM ROUTING
9 CALCULATIONS
TN-LOADING CALCULATIONS
1 O PHASES 1, 2, & 4
11 SUBBASIN #1 ANALYSIS

•
PRECIPITATIONDATA
•

HIGHLAND CREEK
CTX-06070

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HIGHLAND CREEK
CTX-06070

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HIGHLAND CREEK WATERSHED SOIL B.R. FINCH, PE
CTx-04020 INFORMATION x/27/2005
Sub-basin #1
•
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOII.,
CONSERVATION SERVICE: 1986.
Symbol Name Soil. Classltlcation
WmB Wedowee sandy loam B
WmB2 Wedowee sandy loam B
References:
1. SOIL SURVEY• WAKE C9UNTY NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERI1viENT
ConeIusions:
The predominant hydrologic soil -group within the studied watersheds is HSG'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
e Open 61
• Wooded SS
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL B.R. FINCH, PE
CTX-04020 INFORMATION 4/27/2005
Sub-basin #2
Symbol Name Soil Classification
WmB2 Wedowee sandy loam B
WmC2 Wedowee sandy loam B
References:
1. SOIL. SURVEY• WAKE COUNTY, NORTH CAROLINA. UNTIED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROL-INA AGRICULTURE EXPERIMENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
Open 61
Wooded 55
•
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL
CTX-04020 INFORMATION
Sub-basin #3A

Symbol Name Soil Classification
LoC Louisburg loamy sand B
LoD Louisburg loamy sand ~ B
LwB Louisburg-Wedowee complex B
LwB2 Louisburg-Wedowee complex B
LwC Louisburg-Wedowee complex B
LwC2 Louisburg-Wedowee complex B
WkE Wake soils D
WmB2 Wedowee sandy loam B
Wo Wedhadkee & Bibb soils D / C
B.R. FINCH, PE
4/27/2oas
References:
1. SOIL SURVEY• WAKE COUNTY, NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WTfH NORTH. CAROLINA AGRICULTURE EXPERIMENT
STATION). MAPS #2l, 22, 30, 31.
2. SCS TR-55. UNTIED STATES DEPARTMENT OF AGRICULTURE, SOIL
CONSERVATION SERVICE. 1986..
• Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore,. SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
r. Open 61
Wooded 55
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL
CTx-oao2o INFORMATION
Sub-basin #3B
- -----
Symbol Name Soil Classification
LwB Louisburg-Wedowee complex B
- -LwB2 Louisburg-Wedowee complex B
LwC Louisburg-Wedowee complex B
WkE Wake soils D
WmB2 Wedowee sandy loam B
WmC2 Wedowee sandy loam B
Wo Wedhadkee & Bibb soils D ! C
B.R. FINCH, PE
4/27/2005
References:
1. SOIL SURVEY• WAKE COUNTY, NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPER1IvIENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIE.,
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
• Curve numbers will be chosen as follows.•
Cover. SCS Curve Number
Open 61
Wooded 55
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL B.R. FINCH, PE
c'rx-04020 INFORMATION 4/27/2005
Sub-basin #3C
_ •
Symbol Name Soil Classification
DuC Durham loamy sand B
• ~ LoD - Louisburg loamy sand B
LwB Louisburg-Wedowee complex B
LwB2 Louisburg-Wedowee complex B
LwC Louisburg-Wedowee complex B
LwC2 Louisburg-Wedowee complex B
Me Mantachie soils C
WmB Wedowee sandy loam B
WmB2 Wedowee sandy loam B
WmC2 Wedowee sandy loam B
Wo Wedhadlcee & Bibb soils D / C
Wy Worsham sandy loam D
References:
1. SOIL SURVEY• WAKE COUNTY NORTH CAROLINA. UNTIED STATES
DEPAR'TIVIENT OF AGRICULTURE: SOIL CONSERVATION SERVICE ~
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIMENT
STATION). MAPS #21, 22, 30, 31.
• 2. SCS TR-SS. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
Open 61
Wooded 55
Impervious 98
s

HIGHLAND CREEK WATERSHED SOIL B.R. FINCH, PE
cTx-o4o2a INFORMATION 4/27/2005
Sub-basin #4
•
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNTIED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Symbol Name Soil Classification
DuC Durham loamy sand 13
WmB Wedowee sandy loam 13
WmC Wedowee sandy loam B
WmC2 Wedowee sandy loam 13
Wy Worsham sandy loam D
References:
1. SOIL SURVEY• WAKE COUNTY. NORTH CAROLINA. UNTIED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIMENT
Cone~usions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as fodlows:
• Cover SCS Curve Number
Open 61
Wooded 55
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL
CTx-oao2o INFORMATION
Sub-basin #S
• --
Symbol Name Soil Classification
LwB Louisburg-Wedowee complex B
LwC2 Louisburg-Wedowee complex ,. B
WkC Wake soils D
WkE Wake soils D
WmB Wedowee sandy loam B
WmB2 Wedowee sandy loam B
WmC Wedowee sandy loam B
B.R. FINCH, PE
4/27/2005
References'
1. SOII.. SURVEY• WAKE COUNTY -NORTH CAROLINA. UNTIED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIIviENT
STATION). MAPS #21, 22,.30, 31.
2. SCS TR-55. UNITED STATES DEPARTMENT Oh AGRICULTURE. SOII,
CONSERVATION SERVICE. 1986.
Conclusions:
The soils in this watershed are split approx. 50/Sl! between hydrologic soil group (HSG) "B' and HSG 'D'
• Curve numbers will be chosen as follows:
Cover SCS Curve Number Comments
Open 71 = 0.5*61 + 0.5*80
Wooded 66 = 0.5*55 + 0.5*77
Impervious 98 -
•

HIGHLAND CREEK WATERSI~ED SOIL B.R. FINCH, PE
cTX-04020 INFORMATION 4/27/2005
Sub-basin #6A
•

Symbol
Name _-
Soil Classification
ApB Appling sandy loam B
ApB2 Appling sandy loam • B
ApC Appling. sandy loam B
ApC2 Appling sandyloam B
Cn Colfax sandy loam C
DuB Durham loamy sand B
DuC Durham loamy sand B
LoB Louisburg loamy sand. B
LwB2 Louisburg-Wedowee complex B
LwC2 Louisburg-Wedowee complex B
Me Mantachie soils C
WkC Wake soils D
WmB Wedowee. sandy loam B
WmB2 Wedowee sandy loam B
WmC Wedowee sandy loam B
WmC2 Wedowee. sandy loam B
Wo Wedhadkee & Bibb soils D / C
Wy Worsham sandyloam D
. References:
1. SOIL SURVEY• WAKE COUNTY, NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL, CONSERVATION SERVICE (LN
COOPERATION WTI'H NORTH CAROLINA AGRICULTURE EXPERIl~IENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNTTED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
Open 61
Wooded 55
Impervious 98

HIGHLAND CREEK WATERSHED SOIL
CTX-04020 INFORMATION
Sub-basin #6B

Symbol Name Soil Classification
Cn Colfax sandy loam C
DuB Durham loamy sand B
LoC Louisburg loamy sand B
LwB Louisburg-Wedowee complex B
LwB2 Louisburg-Wedowee complex B
LwC Louisburg-Wedowee complex B
WkE Wake soils D
WmB Wedowee sandy loam B
WmB2 Wedowee sandy loam B
WmC Wedowee sandy loam B
WmC2 Wedowee sandy loam B
Wo Wedhadkee & Bibb soils D / C
Wy Worsham sandy loam D
B.R. FINCH, PE
4/27/2005
References:
1. SOIL SURVEY- WAKE COUNTY, NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOII, CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIlVIENT
STATION). MAPS #2.1, 22, 30, 31.
• 2. SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
Olen 61
Wooded 55
Impervious 98

l3IGHLAND CREEK WATERSHED SOIL
cTX-o4o2o INFORMATION
Sub-basin #6C
•
Symbol Name Soil Classification
LoD Louisburg loamy sand B
- LwB2 Louisburg-Wedowee.complex ~ B
LwC Louisburg-Wedowee complex B
LwC2 Louisburg-Wedowee complex B
Me Mantachie soils C
WmB2 Wedowee sandy loam B
WmC Wedowee sandy loam B
WmC2 Wedowee sandy loam B
Wo Wedhadkee & Bibb soils D / C
Wy Worsham sandy loam D
B.R. FINCH, PE
4/27/2005
References:
1. SOIL SURVEY• WAKE COUNTY. NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIIv1ENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55: UNTIED STATES DEPARTMENT OF AGRICULTURE. SOIL,
CONSERVATION SERVICE. 1986.
• Conclusions:
The predominant hydrologic soil group within the studied waterstreds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve. Number
Open 6I
Wooded 55
Impervious 98
•

HIGHLAND CREEK WATERSHED SOH. B.R. FINCH, PE
CTX-04020 INFORMATION 4/27/2005
Sub-basin #7
S mbol Name Soil Classification
LwB2 Louisburg-Wedowee complex B
.. .. LwC2 Louisburg-Wedowee complex B
WmB2 Wedowee sandy loam B
WrnC2 Wedowee sandy loam B
References:
1. SO1L SURVEY: WAKE COUNTY. NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WTI'H NORTH CAROLINA AGRICULTURE EXPERIl~IENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNITED STATES DEPARTMENT OF AGRICULTURE. SOIL
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
• Open 61
Wooded 55
Impervious 98
•

HIGHLAND CREEK WATERSHED SOIL B.R. FINCH, PE
CTX-04020 INFORMATION 4/27/2005
Sub-basin #8
S bol Name Soil Classification
WmB2 Wedowee sandy loam B
References:
1. SOIL SURVEY: WAKE COUNTY. NORTH CAROLINA. UNITED STATES
DEPARTMENT OF AGRICULTURE: SOIL CONSERVATION SERVICE (IN
COOPERATION WITH NORTH CAROLINA AGRICULTURE EXPERIMENT
STATION). MAPS #21, 22, 30, 31.
2. SCS TR-55. UNTIED STATES DEPARTMENT OF AGRICULTURE. SOII,
CONSERVATION SERVICE. 1986.
Conclusions:
The predominant hydrologic soil group within the studied watersheds is HSG 'B'. Therefore, SCS
Curve numbers will be chosen as follows:
Cover SCS Curve Number
Open 61
Wooded. 55
Impervious. 98

•

•
PRE-DEVELOPMENT HYDROLOGIC
CALCULATIONS

r~
HIGHLAND CREEK
CTX-06070

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HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 1 5/17/2007
I. SCS CURVENiTMBE12_ti
• Cover Condition SCS CN Comments
__.._ Impervious.___.._._ ._.~_..____....__ 98._..__.~___._.... __ ~_~_.._...~~_..__~_____ _------
O en 61 Assume ood condition
Wooded 55 Assume good condition
II. PRE'-DEVELOPI4IENT
_> Sub-basin #1
A. Watershed Breakdown
Contributing Area SCS CN Area ~acres~ Comments
_ On-site open 61 ~_
~ 2.53_ _
~ _~~mm Assumegood condition _ _
___
On-site im ervious 98 0.58 -
_ On-site wooded 55 ____ 0.14 ~ _ Assum_ a good_oondition _~ _ ~~
~
On-site and 100 0.00 -
_ Off-site men ~_ 61 ~
~ 0.00_
~
~ ~~ Assume good condition _
Off-site im ervious 98 0.00 -
Off-site wooded
____......
___.
______. 55
.....
____...._._V_____.__.___/.
_. 0.00
_~._.___.~~~.~ Assume o~od condition_~~_~_
._. _.~.____.__~~._
.W _
._
__
Off-site Pond _
_
100 0.00 -
•
Total area = 3.25 acres
0.0051 sq.mi.
Composite SCS CN = 67
Impervious = 17.8%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Segment 2: Concentrated Flow
Length = 100 ft
Height = 3 ft
Slope = .0.0300 ft1ft
Manning's n = 0.24 Dense grasses
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = ll.4d minutes
Length = 421 ft
Height = 20 ft
Slope = 0.0475 ft/ft
Paved ? = No
Velocity = 3.52 ft/sec
Segment Time = 2. t)0 minutes
Time of Concentration = 13.44 minutes
SCS Lag Time = 8.06 minutes (SCS Lag = 0.6* Tc)
= 0.1344 hours
Time Increment = 2.34 minutes (= 0.29*SCS Lag)
•

11. PRE-DEl'ELOPMENT
_> Sub-basin #2
A. Watershed Breakdown
Contributing Area SCS CN Area [acres] Comments
_ O_n-site open _ ___ _ 61 _ 0.15 ~ Assume ood condition _~~
On-site im ervious 98 0.23 -
_ On_site wooded
On-site and 55
100 7.99
0.00 Assume good condition _ ____
-
_..__._Off_site open ___.
Off site im ervious _._..__----_._-_._61.--.__..---__..-_-..
98 ___.___0.00____..
0.00 ---~_ ____ ..___._ Assume good condition ___..___.---__.__.._......
-
Off-site wooded
Off-site Pond __._55__....._____._..._._.........
100 ._......_0.00_......_.
0.00 _.._......__._. _ _._. _._._Assume_good condition ____._____..__._..___._._.._
-
C7
Total area = 8.37 acres
0.0131 sq.mi.
Composite SCS CN = 56
Impervious = 2.7%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-SS.
Segment I: Overland Flow
Length = 100 ft
Height = 6 ft
Slope = 0.0600 ft/ft
Manning's n = 0.40 Wooded -dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 13.05 minutes
Time of Concentration = 14.31 minutes
SCS Lag Time = 8.59 minutes (SCS Lag = 0.6* Tc)
= 0.1431 hours
Time Increment = 2.49 minutes (= 0.29*SCS Lag)
HIGHLAND CREEK
CTX-06070
I. ,SCti CLIRti'E ~UM13~R.~
HYDROLOGIC CALCULATIONS
Pre-Development - Subbasin 2
Cover Condition SCS CN Comments
__ Impervious ~__ 98 _._____ ___ - _
Open 61 Assume ood condition
Wooded 55 Assume good condition
J. ALDRIDGE, EI
5/17/2007
Segment 2: Concentrated Flow
Length = 284 ft
Height = 15.2 ft
Slope = 0.0535 ft1ft
Paved ? = No
Velocity = 3.73 ft/sec
Segment Time = T.27 minutes
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 3A 5/17/2007
1. tiC5 CURVE NU'FTI3FRS
• Cover Condition SCS CN Comments
_._._.._..___~~ervious____.._._ .
.
.
._._
__98__
__
._ _
_
_
_
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_.
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.
_
_
61 Assume ood condition
Wooded 55 Assume good condition
IL PI3E~DEVELOPMENT
_> Sub-basin #3A
A. Watershed Breakdown
Contributing Area SCS CN Area [acres] Comments
_ _On-s_ ___'te open ~
v ~_ 61 0.00 ___ Assume good condition _
On-site im ervious 98 0.00 -
On-site wooded
On-site pond 55
100
~ 0.00
0.00 Assume good condition
-
Off-site open , _ f
Off-site im ervious _.~
._ _ , _61 ____
98 5.97
0.05 Assum~ood condition
-
Off-site wooded ~
Off-site Pond 55
100 57.41
0.00 Assume ood condition
-
Total area = 63.43 acres
0.099] sq.mi.
Composite SCS CN = 56
Impervious = 0.1%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
•
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length = 100 ft Length = 580 ft
Height = 5.5 ft Height = 43 ft
Slope = 0.0550 ft/ft Slope = 0.0741 ft/ft
Manning's n = 0.40 Wooded -dense underbrush Paved ? = No
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) Velocity = 4.39 ft/sec
Segment Time = 13.51 minutes Segment Time = 2.10 minutes
Segment 3: Channel Flow Segment 4: Channel Flow
Length = 490 ft Length = 760 ft
Height = 44 ft Height = 4 ft
Slope = 0.0898 ft/ft Slope = 0.0053 ft/ft
Manning's n = 0.045 Natural Channel Manning's n = 0.045 Natural Channel
Flow Area = 1.00 sf (Assume 1' x 1' Channel) Flow Area = 64.00 sf (Assume 8' x 8' Channel)
Wetted Perimeter = 3.00 ft (Assume 1' x I' Channel) Wetted Perimeter = 24.00 ft (Assume 8' x 8' Channel)
Channel Velocity = 4.77 ft/sec Channel Velocity = 4.(i2 ftlsec
Segment Time = 1.71 minutes Segment Time = 2.74 minutes
Time of Concentration = 20.16 minutes
SCS Lag Time = 12.10 minutes (SCS Lag = 0.6* Tc)
= 0.2016 hours
Time Increment = 3.51 minutes (= 0.29*SCS Lag)
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 3B 5/17/2007
I. SCS CURVIJ M?MRFRS
•
Cover Condition SCS CN Comments
Im ervious
__._. ____-._E. _ ~...._.___...._ 98 -
~ _._.._...._.......__ ______.__._._________ _ _ __~___._.__
O en 61 Assume ood condition
Wooded 55 Assume good condition
[I. PRE-DEVELOPMENT
_> Sub-basin #3B
A. Watershed Breakdown
Contributing Area SCS CN Area [acres] Comments
O_____n_site omen _ 61
~ 0.00 Assume good condition
On-site im ervious 98 0.00 -
__ ____On-site wooded_ __
On-site and 55
100 ~ 8.61
0.00 _. ~._._.__.___..._._._~___ Assume good condition_________~___ _~T__
-
__. -_.__Offaite open _ _...__
Off-site impervious .._._._6.1_........
98 _.._..._5.61 ____ _
0.17 ~_,_ _ .__.._..__._.____. Assum~ood condition _~_~~._-__~~.
-
Off-site wooded
Off-site Pond 55
100 18.12
0.00 Assume good condition ___.__.____..___.___. _
-
Total area = 32.51 acres
0.0508 sq.mi.
Composite SCS CN = 56
Impervious = 0.5%
•
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 2: Concentrated Flow
Length = 1320 ft
Height = 68.8 ft
Slope = 0.0521 ft/ft
Paved ? = No
Velocity = 3.68 ft/sec
Length = 100 ft
Height = 2.2 ft
Slope = 0.0220 ft/ft
Manning's n = 0.24 Dense grasses
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 12.95 minutes
Segment 3: Channel Flow
Length = 904 ft
Height = 34 ft
Slope = 0.0376 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 4.00 sf (Assume 2' x 2' Channel)
Wetted Perimeter = 6.00 ft (Assume 2' x 2' Channel)
Channel Velocity = 4.90 ft/sec
Segment Time = 3.0? minutes
Segment Time = 5.9; minutes
Segment 4: Channel Flow
Length = 245 ft
Height = 6 ft
Slope = 0.0245 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel)
Channel Velocity = 4.59 ft/sec
Segment Time = t1.~49 minutes
Time of Concentration = 22.89 minutes
SCS Lag Time = 13.73 minutes (SCS Lag = 0.6* Tc)
= 0.2289 hours
Time Increment = 3.98 minutes (= 0.29*SCS Lag)
Segment 1: Overland Flow
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 3C 5/17/2007
L SCS CURVI: NL??41BERS
• Cover Condition SCS CN Comments
Impervious 98 -
_...._._............._-_~Pe.°..______.____.. ._._..__.6_~.........._.
_ _.._ Assume ood condition
_._...._..___....__ _.Pz_ _ _ __.___...__._.._
Wooded 55 Assume good condition
II. PI2k=-DEVELOPME}VT
_> Sub-basin #3C
A. Watershed Breakdown
Contributing Area SCS CN Area
]acres] Comments
On-site men _ 61 _ 23.25 ~ _ ~ Assume good condition
On-site impervious __ 98__ 4.69 -
On site wooded 55 50.71 Assume mood condition
On-site pond
_
_ _100
.
_.
__
_
.__ -1.43 ._..__
__ _....... ---.- -. _____ __. _._. __.__ .-_._. ~. _~_______.__ . __.
.....
_.
__.....__
_ Off_site open _ _ .
.
..
..
_
.
__ 61 .
._.
2.34 .
Assumegzood condition
__ ,Off-site impervious__ _ _ 98 __ 0.01 -
Off-site wooded 55 5.02 Assume good condition _~~~
Off-site Pond 100 0.00 -
•
Total area = 87.45 acres
0.1366 sq.mi.
Composite SCS CN = 60
Impervious = 5.4%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment l: Overland Flow
Length = 1070 ft
Height = 39 ft
Slope = 0.0364 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 4.00 sf (Assume 2' x 2' Channel)
Wetted Perimeter = 6.00 ft (Assume 2' x 2' Channel)
Channel Velocity= ~1.8_ ft/sec
Segment Time = 13.81 minutes
Segment 3: Channel Flow
Length = 100 ft
Height = 5.2 ft
Slope = 0.0520 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment 2: Concentrated Flow
Length = 516 ft
Height = 35 ft
Slope = 0.0678 ft/ft
Paved ? = No
Velocity= 4.2t) ft/sec
Segment Time = 2.05 minutes
Segment 4: Channel Flow
Length = 1396 ft
Height = 35 ft
Slope = 0.0251 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel)
Channel Velocity = 4.Ei4 ft/sec
Segment Time = .5.01 minutes
Segment Time = 3.'(1
Segment 5: Channel Flow
Length = 1293
Height = 12
Slope = 0.0093
Manning's n = 0.045
Flow Area = 25.00
Wetted Perimeter = 15.00
Channel Velocity= 4.413
minutes
ft
ft
ft/ft
Natural Channel
sf (Assume 5' x 5' Channel)
ft (Assume 5' x 5' Channel)
ft/sec
Segment Time = 4.81 minutes
•
Time of Concentration = 29.38 minutes
SCS Lag Time = 17.63 minutes (SCS Lag = 0.6* Tc)
= 0.2938 hours
Time Increment = 5.1 ] minutes (= 0.29*SCS lag)

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 4A 5/17/2007
I. SCS'Ct1RVH' NI1111BERS
• Cover Condition SCS CN Comments
Impervious 98
_
__......._..._
_.__.__.--..
O en .._.._._._..___
._...._.._....____.i.........._..__.__~_._.._
__..__ _._____...___.
61 ~ Assume good condition
~
Wooded 55 ~V
-~-- Assume ood condition
II. PRL-DEVELOPMENT
_> Sub-basin #4A
A. Watershed Breakdown
Contributing Area SCS CN (Area ]acres] Comments
On-site o en 61 0.39_ Assume good condition

On-site im ervious
98 0.08 _ _
-
Omsite wooded 55 ~ 21.04 Assume good condition
__
_
On-site and 100 0.00 -
Off-site open b l ~ 2.27 Assume~ood condition _ ~~ ~_ _.
Off-site im ervious 98 E 0.20 -
Off-site wooded 55 ! 0.54 Assume good condition
Off-site Pond 100 ~ 0.00 -
.7
Segment 2: Concentrated Flow
Length = 100 ft Length = 541 ft
Height = 2.1 ft Height = 24.4 ft
Slope = 0.0210 ft/ft Slope = 0.0451 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush Paved ? = No
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) Velocity = 3.43 ft/sec
Segment Time = 19.45 minutes Segment Time = 2.63 minutes
Segment 3: Channel Flow
Length = 749 ft
Height = 34 ft
Slope= 0.0454 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 2.25 sf (Assume 1.5' x 1.5' Channel)
Wetted Perimeter = 4.50 ft (Assume 1.5' x 1.5' Channel)
Channel Velocity = 4.44 ft/sec
Segment Time = 2.81 minutes
Time of Concentration = 25.29 minutes
SCS Lag Time = 15.18 minutes (SCS Lag = 0.6* Tc)
= 0.2529 hours
Time Increment = 4.40 minutes (= 0.29*SCS Lag)
Total area = 24.52 acres
0.0383 sq.mi.
Composite SCS CN = 56
Impervious = 1.1
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 48 5/17/2007
I. S('S CURVE: NUMBERS
• Cover Condition SCS CN Comments
Im_pervious_
_.___.___._. _.__ _ 98 -
_____.___________.._.. _..~___ _____.__m.e________.~__
en 61 Assume ood condition
Wooded 55 Assume good condition
lI. PRE=DEVELOPMENT
_> Sub-basin #4B
A. Watershed Breakdown
•
Segment 2: Concentrated Flow
Length = 584 ft
Height = 36.8 ft
Slope = 0.0630 ft/ft
Paved ? = No
Velocity= 4.0~ ft/sec
Segment Time = ?.4D minutes
Length = 241 ft
Height = 11.6 ft
Slope = 0.0481 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 2.25 sf (Assmne 1.5' x 1.5' Channel)
Wetted Perimeter = 4.50 ft (Assume 1.5' x 1.5' Channel)
Channel Velocity= 4.i8 ft/sec
Segment Time = D.RB minutes
Length = 100 ft
Height = 2.7 ft
Slope = 0.0270 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 17.96 minutes
Segment 3: Channel Flow
Contributing Area SCS CN Area nacres) Comments
_On-site open 61
______ 0.02
__._ ~ Assume good condition
On-site im ervious 98 0.00 -
On-site wooded
On-site nd 55
100 ! 6.86
0.00 ___._ _ _ _~___ Assume food condition
-
_ _ Off-site_o_pen __
Off--site im ervious _.......__._....._61..__..._._.____.~
98 ~ _____~_~~_-.--_
0.00 _,.__..___....__._____.__._._Assume good condition __~~_._____.__
-
Off-site wooded
Off-site Pond 55 ~
100 0.00
0.00 Assume food condition _~___~ _
-
Total area = 6.88 acres
0.0108 sq.mi.
Composite SCS CN = 55
Impervious = 0.0%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-SS.
Segment l: Overland Flow
Time of Concentration = 21.24 minutes
SCS Lag Time = 12.74 minutes (SCS Lag = 0.6* Tc)
= 0.2124 hours
Time Increment = 3.70 minutes (= 0.29*SCS Lag)
r]

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 4C 5/17/2007
t. 5CS CCTI2VE NUMBERS
• Cover Condition SCS CN Comments
~-Impervious.____.___.. _...__.__.._._98.__...__.___.l-.._..______...~__..~._..,___.__---_..__.--
O en 61 € Assume ood condition
Wooded 55 ~ Assume good condition
II. PRE-DEVELOPMENT
_> Sub-basin #4C
A. Watershed Breakdown
C~
Length = 100 ft
Height = 2 ft
Slope = 0.0200 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 20.25 minutes
Contributing Area SCS CN Area [acres] Comments
On-site o en 61 0.11 _ Assume good condition
_
On-site im ervious _______ 98 _ 0.00 ~ -
On-site wooded
On-site and 55 ~
100 1.03
~ 0.00 Assume good condition
-
_ ._____Off--site oPen~ _.._
Off-site im ervious .._. __._._.__61._..._____
98 }.___._. ~~~~_..___.
0.00 _____.___ . _____...__Assume mood condition
-- -_________ _._.
Off-site wooded
Off-site Pond 55
100 ~ 0.00
0.00 Assume good condition __~_~_
-
Total area = 1.14 acres
0.0018 sq.mi.
Composite SCS CN = 56
Impervious = 0.0%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-S5.
Segment 1: Overland Flow
Time of Concentration = 20.90 minutes
SCS Lag Time = 12.54 minutes (SCS Lag = 0.6* Tc)
= 0.2090 hours
Time Increment = 3.64 minutes (= 0.29*SCS Lag)
Segment 2: Concentrated Flow
Length = 151 ft
Height = 8.5 ft
Slope = 0.0563 ft/ft
Paved ? = No
Velocity = 3.33 ft/sec
Segment Time = 0.66 minutes
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin5 5/17/2007
I. SCS C[iKVE NLIMBRRS
• Cover Condition SCS CN Comments
__ __.__hn~rvious T _._.._98.___..___..___..__._...._._.....__.__.._..._._._'.._._._..___...__._~__.. ____
en 71 ~ Assume good condition
Wooded 66 Assume good condition
II'. PRE-DEVELOPMENT
_> Sub-basin #S
A. Watershed Breakdown
Contributing Area SCS CN Area (acres) Comments
_~_On~site omen ~mm ~, 71 ~_ 8.32 __
_ Ass_u_me_pood condition _ _ _
~ v
~^ ~
On-site im ervious 98 i 0.45 -
On-site wooded 66
41.79 Assume~ood condition
___--_----_ ____._ _ ________
_
__._ _
____
On-site and _
_ _
r_._.. _ ____ . ___
100 0.00 __ ._ ... _..~....____ _._. _.
.
.
-
~.___.Off. site open ___ _ _ ____ 7I __„_ _~ ~ __ 0.44 Assume pZood condition
Off-site im ervious 98 0.17 -
Off-site wooded 66 0.00 Assume food condition
Off-site Pond 100 0.00 -
Total area = 51.17 acres
0.0800 sq.mi.
Composite SCS CN = 67
Impervious = 1.2%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-SS.
• Segment l: Overland Flow
Length = 100 ft
Height = 1.8 ft
Slope = 0.0180 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 21.12 minutes
Segment 3: Channel Flow
Length = 349 ft
Height = 24 ft
Slope= 0.0688 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 1.00 sf (Assume 1' x 1' Channel)
Wetted Perimeter = 3.00 ft (Assume 1' x 1' Channel)
Channel Velocity = 4.17 ft/sec
Segment Time = I.39 minutes
Segment 2: Concentrated Flow
Length = 825 ft
Height = 45 ft
Slope = 0.0545 ftJft
Paved ? = No
Velocity = 3.77 ft/sec
Segment Time = 3.b5 minutes
Segment 4: Channel Flow
Length = 811 ft
Height = 23.2 ft
Slope = 0.0286 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 4.00 sf (Assume 2' x 2' Channel)
Wetted Perimeter = 6.00 ft (Assume 2' x 2' Channel)
Channel Velocity = 4.27 ft/sec
Segment Time = 3.Ib minutes
Time of Concentration = 29.32 minutes
SCS Lag Time = 17.59 minutes (SCS Lag = 0.6* Tc)
= 0.2932 hours
Time Increment = 5.10 minutes (= 0.29*SCS Lag)
•

•
HIGHLAND CREEK
CTX-06070
I. SCS CC)RV;E \'L;\1 tlelt
HYDROLOGIC CALCULATIONS
Pre-Development - Subbasin 6A
Cover Condition SCS CN Comments
_____. Impervious 98 _ _.. __..___.-
O en 61 Assume good condition
Wooded 55 Assume ood condition
H. PRE»D~V>~LOP)viF,~i'1'
_> Sub-basin #6A
A. Watershed Breakdown
Contributing Area SCS CN Area ~ Comments
~acresJ
On-site open 61 0.00 _ Assume good condition
On-site im ervious 98 0.00 ~~
On-site wooded 55 0.00 Assume ood condition
On-sit~ond_~ 100 0.00 -
____Off-sit~en_~.._._._.
Off--site im ervious m_.__ 61.____...
98 .._113.76 . _ Assume good condition ______. _....._ ______._
13.71
Off-site wooded 55 134.70 s Assume ood condition
Off-site Pond 100 3.38 i -
•
Total area = 265.55 acres
0.4149 sq.mi.
Composite SCS CN = 60
Impervious = 5.2%
B. Time of Concentration Information
Time of concentration !s cala~lated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 fi
Ileight = 5.2 fi
Slope = 0.0520 ft/ft
Manning's n = 0.24 Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 9. l8 minutes
Segment 3: Channel Flow
Length = 865 ft
Height = 22 ft
Slope = 0.0254 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
Wetted Perimeter = 7.50 R (Assume 2.5' x 2.5' Channel)
Channel Velocity= 4.6h ft/sec
Segment Time = 3.08 minutes
Segment 5: Channel Flow
Length = 959 ft
Height = 12.2 ft
Slope = 0.0127 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 16.00 sf (Assume 4' x 4' Channel)
Wetted Perimeter = 12.00 ft (Assume 4' x 4' Channel)
Channel Velocity= 452 ft/sec
Segment 2: Concentrated Flow
Length = 928 ft
Height = 31.8 ft
Slope = 0.0343 ft/ft
Paved ? = No
Velocity= 2.99 ft/sec
Segment Time = 5.1 S minutes
Segment 4: Channel Flow
J. ALDRIDGE, EI
5/17/2007
Length = 840 ft
Height = 22 ft
Slope = 0.0262 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel)
Channel Velocity = 4 ^> ft/sec
Segment Time = 2. l3 minutes
Segment Time = 3.5.3 minutes
•
Time of Concentration = 23.93 minutes
SCS Lag Time = 14.36 minutes (SCS Lag = 0.6* Tc)
= 0.2393 hours
Time Increment = 4.16 minutes (= 0.29*SCS Lag)

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 6B 5/17/2007

L tiC5 CURVF, NC~TBEKS
Cover Condition SCS CN Comments
~~Impervious_ ~ 98_ .._._ _.__ _-_ - - -.---
en 61 Assume ood condition
Wooded ~ 55 Assume good condition
Contributing Area E SCS CN Area [acres] Comments
On-site open___ __ 61 _0.00 __ Assume~ood condition
~
On-site im ervious 98 0.00 -
On-site wooded !
On-site and ~ 55
100 0.00
0.00 Assume good condition __ _ _________
-
~_ _Off,site open ~i
Off-site im ervious _ _ 61
98 24.71
3.07 Assume~ood condition
-
Off-site wooded
Off-site Pond __ 55
_ 100 58.24
0.16 Assume good condition
___. __.._
Total area = 86.18 acres
0.1347 sq.mi.
Composite SCS CN = 58
Impervious = 3.6%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-SS.
• Segment 1: Overland Flow Segment 2: Concentrated Flow
Length = 100 ft Length = 1401 ft
Height = 4 ft Height = 39 ft
Slope = 0.0400 ft/ft Slope = 0.0278 ft/R
Manning's n = 0.40 Wooded -Dense underbrush Paved ? = No
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) Velocity = 2.fi4 ft/sec
Segment Time = 75.34 minutes Segment Time = B.d? minutes
Segment 3: Channel Flow Segment 4: Channel Flow
Length = 929 ft Length = 1307 ft
Height = 24.2 ft Height = 9.8 ft
Slope = 0.0260 ft/ft Slope = 0.0075 ft/ft
Manning's n = 0.045 Natural Channel Manning's n = 0.045 Natural Channel
Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel) Flow Area = 36.00 sf (Assume 6' x 6' Channel)
Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel) Wetted Perimeter = 18.00 ft (Assume 6' x 6' Channel)
Channel Velocity = 4.73 ft/sec Channel Velocity = 4.~5 ft/sec
Segment Time = 3.2' minutes Segment Time = 4. ?9 minutes
Time of Concentration = 32.08 minutes
SCS Lag Time = 19.25 minutes (SCS Lag = 0.6* Tc)
= 0.3208 hours
Time Increment = 5.58 minutes (= 0.29*SCS Lag)
II. PRE-DEVELOPMENT
_> Sub-basin #6B
A. Watershed Breakdown
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 6C 5/17/2007
L SCS CUR'Vl~: NUMBERS
• Cover Condition ~ SCS CN Comments
_....___....._Im_pervious _._.......__...;......__ _.98._.. __........._..__......_.._..._....______....__..'...._..___..._...__.__._...___._.
Open ~ 61 Assume ood condition
Wooded ~ 55 ~ Assume good condition
II. PRE-LIEVELOPMT;NT
_> Sub-basin #6C
A. Watershed Breakdown
Contributing Area SCS CN Area [acres Comments
_O_n-site_o~en __ 61 _
_
~ _ 18.26 -
- _____~ _ Assume good condition
On-site im ervious 98 1.05 _ -
On-site wooded
On-site and I 55
100 63.23
0.97 Assume good condition _~_~
-
~__Off--site omen ___ I
Off-site im ervious _61~_
98 _._..._.__l 1.23.._._--
3.00 -_ _~.__.__.~______Assume good condition ._.__._ ___________.
-
Off-site wooded i
Off-site Pond 55
100 12.33
0.00 Assume ood condition
-
CJ
Segment 2: Concentrated Flow
Length = 532 ft
Height = 33.8 ft
Slope = 0.0635 ft/ft
Paved ? = No
Velocity = 4.07 ft/sec
Segment Time = 2.18 minutes
Segment 4: Channel Flow
Length = 1146 ft
Height = 10 ft
Slope = 0.0087 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 36.00 sf (Assume 6' x 6' Channel)
Wetted Perimeter = 18.00 ft (Assume 6' x 6' Channel)
Channel Velocity = 4.91 ft/sec
Segment Time = 3.59 minutes
Time of Concentration = 24.10 minutes
SCS Lag Time = 14.46 minutes (SCS Lag = 0.6* Tc)
= 0.2410 hours
Time Increment = 4.19 minutes (= 0.29*SCS Lag)
Total area = 110.07 acres
0.1720 sq.mi.
Composite SCS CN = 59
Impervious = 3.7%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-55.
Segment 1: Overland Flow
Length = 100 ft
Height = 4 fr
Slope = 0.0400 ft/ft
Manning's n = 0.24 Dense grasses
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = IO.l(t minutes
Segment 3: Channel Flow
Length = 2297 ft
Height = 50 ft
Slope = 0.0218 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 9.00 sf (Assume 3' x 3' Channel)
Wetted Perimeter = 9.00 ft (Assume 3' x 3' Channel)
Channel Velocity= 4.89 ft/sec
Segment Time = ' 84 minutes
•

Ih~~'PRE-DEV'ELOPMEN"T
_> Sub-basin #7
A. Watershed Breakdown
Contributing Area SCS CN Area [acres] Comments
_,_ On-site _ o~__ _ ~ 61 0.00 Assume ood condition
On-site im ervious I 98 0.00 -
On-site wooded i 55
On-site and 100 1.33
0.00 Assume~ood condition
-
____ Off-site open~_ a_ __ _61 __
Off-site im ervious 98 __0.00_ __
000 Assume good condition _ ~_ ~_ ~_.
___.__~._._- ~~~~
Off-site wooded ! 55
_.._~_.._ _ _...__.__.._. _ _ _..__i.~ __.__~___. _._.
Off-site Pond 100 0.19
_.___ . _. _~_._
0.00 Assume good condition _
_._~. _ _ _ _ _..._.._~__._. _._ ~_..._____
-
•
Time of Concentration = 14.41 minutes
SCS Lag Time = 8.64 minutes (SCS Lag = 0.6* Tc)
= 0.1441 hours
Time Increment = 2.51 minutes (= 0.29*SCS Lag)
HIGHLAND CREEK
CTX-06070
1, SCS CURVI!11~iti~T13EFL5
HYDROLOGIC CALCULATIONS
Pre-Development - Subbasin 7
Cover Condition SCS CN Comments
Impervious € 98
O en i~ _ 61 ______~: _ ~____
Assume ood condition
Wooded `€ 55 Assume good condition
Total area = 1.52 acres
0.0024 sq.mi.
Composite SCS CN = 55
Impervious = 0.0%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-S5.
Segment 1: Overland Flow
Length = 100 ft
Height = 5 ft
Slope = 0.0500 ft/ft
Manning's n = 0.40 Wooded -Dense underbrush
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = Id.U3 minutes
Segment 2: Concentrated Flow
Length = 113 ft
Height = 11 ft
Slope = 0.0973 ft/ft
Paved ? = No
Velocity= 5.(13 ft/sec
Segment Time = U.37 minutes
J. ALDRIDGIa, EI
5/17/2007

HIGHLAND CREEK I3YDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre-Development - Subbasin 8 5/17/2007
t. SCS CURVE NU11t3EIL'S
• Cover Condition SCS CN Comments
___..._h"pervious __ _ _ _._.~~._ .._._._ 98 ~ _..._...._._ ..~ _______... - .__._._..____..~.
en 61 Assume ood condition
Wooded 55 Assume good condition
11. PRE-DEy'EL.OPMENI'
_> Sub-basin #8
A. Watershed Breakdown
•
Contributing Area SCS CN Area [acres] Comments
__ On-site open _ 61 5.14 Assume ood condition
On-site im ervious 98 0.13 -
On-site wooded 55
_
___ 0.17 Assume good condition
_ _
___
On-site and _~
_
__~ ___
100 0.00 -
~__ Off-site open
Off-site im ervious ~ _ _ _61~_____~~_
98 _-_ _0.00 _
0.00 __ _ _ ~ Assum~od condition _~_~
-
Off-site wooded
_.___._..._.._.._._. __ ~_. ~_..__.....
Off-site Pond 55
.__._._.__..__~._.---.._.~.__..__
100 0.00
.__~._._.____.
0.00 Assume ood condition ~ ~__
_.__.._._____.__y____V___
-
Total area = 5.44 acres
0.0085 sq.mi.
Composite SCS CN = 62
Impervious = 2.4%
B. Time of Concentration Information
Time of concentration is calculated using SCS TR-SS.
Segment 1: Overland Flow Segment 2: Concentrated Flow
Length = 100 R Length = 370 ft
Height = 1.8 ft Height = 15 ft
Slope = 0.0180 ft/ft Slope = 0.0405 ft/ft
Manning's n = 0.24 Dense grasses Paved ? = No
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) Velocity = 3.25 ft/sec
Segment Time = 14.03 minutes Segment Time = 1.90 minutes
Time of Concentration = 15.93 minutes
SCS Lag Time = 9.56 minutes (SCS Lag = 0.6* Tc)
= 0.1593 hours
Time Increment = 2.77 minutes (= 0.29*SCS Lag)
•

•
HIGHLAND CREEK CALCULATION OF REACH LAG TIMES
CTX-04020 Pre-Development
*Lag times are calculated assuming a S-ft/sec velocity.
T = (L / V) *(1 minute / 60 seconds)
Where:
T = Lag Time (min)
L = Reach Length (ft)
V = Flow Velocity (ft/sec)
Reach Length [feet] ""5 `""`
minutes
1 1143 3.81
2 1587 5.29
3 1289 4.30
4 2115 7.05
5 1322 4.41
J. ALDRIDGE, EI
5/17/2007
•

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HMS * Summ<
Project CTS-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 11Jun07 1454
pry of Results
Run Name PRE - Q2
Basin Model PR8
Met. Model Q2
Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Subbasin 5 37.374 16 Feb 07 2022 3.8356 0.080
Subbasin 1 3.5417 16 Feb 07 2011 0.24551 0.005
Subbasin 2 2.6332 16 Feb 07 2015 0.28884 0.013
Subbasin 8 3.5270 16 Feb 07 2014 0.29869 0.009
Reach 4 3.5270 16 Feb 07 2021 0.29791 0.009
Subbasin 7 0.40668 16 Feb 07 2015 0.048300 0.002
Reach 1 0.40668 16 Feb 07 2018 0.048232 0.002
Subbasin 6A 112.56 16 Feb 07 2021 12.613 0.415
Junction 1 112.95 16 Feb 07 2021 12.661 0.417
Reach 2 112.95 16 Feb 07 2026 12.636 0.417
Subbasin 6B 24.419 16 Feb 07 2028 3.4978 0.135
Subbasin 6C 41.303 16 Feb 07 2021 4.8470 0.172
Junction 2 175.82 16 Feb 07 2025 20.981 0.724
chi 175.82 16 Feb 07 2029 20.946 0.724
basin 3A 17.135 16 Feb 07 2020 2.1805 0.099
Junction 3 191.94 16 Feb 07 2028 23.425 0.832
Reach 5 191.94 16 Feb 07 2032 23.386 0.832
Subbasin 3B 8.2831 16 Feb 07 2022 1.1167 0.051
Subbasin 3C 33.137 16 Feb 07 2025 4.1456 0.137
Junction 4 227.68 16 Feb 07 2032 28.648 1.019
Subbasin 4A 5.9451 16 Feb 07 2024 0.84119 0.038
Subbasin 4B 1.5529 16 Feb 07 2021 0.21680 0.011
Subbasin 4C 0.30643 16 Feb 07 2020 0.039596 0.002
•

HMS * Summary of Results
Project CTS-06070 Run Name PRS - Q10
• Start of Run 16Feb07 0800 Basin Model PRS
Snd of Run : 17Feb07 0800 Met. Model Q10
Execution Time 17May07 1534 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Subbasin 5 85.237 16 Feb 07 2021 8.7760 0.080
Subbasin 1 7.6929 16 Feb 07 2010 0.56144 0.005
Subbasin 2 10.262 16 Feb 07 2012 0.86413 0.013
Subbasin 8 9.3705 16 Feb 07 2012 0.75697 0.009
Reach 4 9.3705 16 Feb 07 2019 0.75531 0.009
Subbasin 7 1.7342 16 Feb 07 2012 0.14961 0.002
Reach 1 1.7342 16 Feb 07 2015 0.14944 0.002
Subbasin 6A 339.79 16 Feb 07 2018 33.577 0.415
Junction 1 341.44 16 Feb 07 2018 33.727 0.417
Reach 2 341.44 16 Feb 07 2023 33.671 0.417
Subbasin 6B 83.484 16 Feb 07 2025 9.8423 0.135
Subbasin 6C 131.94 16 Feb 07 2019 13.251 0.172
Junction 2 548.32 16 Feb 07 2023 56.765 0.724
each3 548.32 16 Feb 07 2027 56.689 0.724
basin 3A 67.114 16 Feb 07 2016 6.5264 0.099
nction 3 606.03 16 Feb 07 2026 63.971 0.832
Reach 5 606.03 16 Feb 07 2030 63.884 0.832
Subbasin 3B 32.434 16 Feb 07 2018 3.3430 0.051
Subbasin 3C 100.88 16 Feb 07 2022 11.039 0.137
Junction 4 719.12 16 Feb 07 2029 78.266 1.019
Subbasin 4A 23.292 16 Feb 07 2020 2.5187 0.038
Subbasin 4B 6.6065 16 Feb 07 2017 0.67192 0.011
Subbasin 4C 1.1998 16 Feb 07 2017 0.11852 0.002
•

•
POST-DEVELOPMENT HYDROLOGIC
CALCULATIONS

HIGHLAND CREEK
CTX-06070

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•
II. POST DEVELOPMENT
_> Subbasin #1
A. Watershed Breakdown

Phase
# Lots
Imp/Lot [sf[ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.00 0.00
1 B 0 3600 0.00 0.00 0.00
2 0.5 4000 0.05 0.48 0.53
3 7.5 4000 0.69
~ _ 0.00 __
~ 0.69
__ _
___
~~ 4 ~ ~ 0~~ _
4000 v 0.00 0.00 0.00
-vtner tmpervaous mc[uaes tmpervious~rom ~ ownnomes, vreenway 1 raus, ana rc~gnr-o~-rray

Total area = 2.76 acres
0.0043 sq.mi.
Composite SCS CN = 77
Impervious = 43.9%
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 1
Cover Condition SCS CN Comments
Im ervious 98 _
_
_ _O_pen _ _61 v__
~ _Assume oog d condition
Wooded 55 Assume good condition
Contributing Area SCS CN Area [acres] Comments
,Onsite i~rvious
Onsite o en _ __98__ __
61 1.21
I.55 -
Assume ood condition
Onsite wooded 55 0.00 Assume good condition
Onsitepond 100 _ 0.00 _ _______~ ______
Offsite impervious 98 0.00 -
Offsite o n 61 0.00 Assume ood condition
Offsite wooded
_ _ 55 _ 0.00
~
~ Assume ood condition
~
Offsite and 100 0.00 -
•

•
HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 2
Cover Condition SCS CN Comments
Impervious 98 _ _ -__
T
~~~Open _ _61 _ __
~ Assume good condition
_
Wooded 55 Assume good condition
II. POST DEVELOPMENT
_> Subbasin #2
A. Watershed Breakdown
J. ALDRIDGE, EI
6/14/2007
Contributing Area SCS CN Area nacres) Comments
_ Onsiteim~erviousW
Onsite o n _~ 98___..._.
61 _.__..__023._._._
0.15 -
Assume ood conditionv___
Onsite wooded 55
~ 7.99
~ Assu~ood condition
~~-
^~
_
_
_ Onsite pond _
_100 _
~ _ 0.00 _,~_~_
Offsite im ervious 98 0.00 -
Offsite o en 61 0.00 Assume ood condition
Offsite wooded 55 0.00 Assume good condition
Offsite and _
_ 100 __
0.00 -
Total area = 8.37 acres
0.0131 sq.mi.
Composite SCS CN = 56
Impervious = 2.7%
•
B. Time of Concentration Information
The post-development time of concentration is equal to the pre-development time of concentration since this Subbasin remains unaltered.
Time of Concentration = 14.31 minutes
SCS Lag Time = 8.59 minutes (SCS Lag = 0.6* Tc)
= 0.1431 hours
Time Increment = 2.49 minutes (= 0.29*SCS Lag)
•

•
HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 3A
Cover Condition SCS CN Comments
hn ervious 98 _
_ __ __ Open _ 61
_ __Assume good condition
Wooded 55 Assume good condition
II. POST DEVELOPMENT
_> Subbasin #3A
A. Watershed Breakdown
J. ALDRIDGE, EI
6/14/2007
Contributing Area SCS CN Area ~acres~ Comments
O_n_site impervious
~ 98 _
____ 0.00_ _
~
~ _ _ - __~_
_
Onsite o n 61 0.00 Assume ood condition
Onsite wooded
Onsitepond
__._ _~_
Offsite im ervious 55
100
_ __ ._r~__._
98 0.00
0.00
~_....._____..__
0.05 Assume good condition
-
_____... _ .__.. V..._ ___.._---___.
-
Offsite o en 61 5.97 Assume ood condition
_Offsite wooded
Offsite and _55_
100 _ _ 57.41_
0.00 v _ Assume good condition _
_~~.
Total area = 63.43 acres
0.0991 sq.mi.
Composite SCS CN = 56
Impervious = 0.1
•
B. Time of Concentration Information
The post-development time of concentration is equal to the pre-development time of concentration since this Subbasin remains unaltered.
Time of Concentration = 20.16 minutes
SCS Lag Time = 12.10 minutes (SCS Lag = 0.6* Tc)
= 0.2016 hours
Time Increment = 3.51 minutes (= 0.29*SCS Lag)

HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 3B
Cover Condition SCS CN Comments
Impervious 98 -
~
Open 61 _
Assume ood condition
Wooded 55 Assume good condition
II. POST DEVELOPMENT
_> Subbasin #3B
A. Watershed Breakdown
J. ALDRIDGE, E]
6/14/2007
Contributing Area SCS CN Area nacres] Comments
_ Onsite impervious 98 __ _ 0.00_ -
Onsite open 61 0.00 Assume ood condition
Onsite wooded _ 55 8.61 Assume~ood condition
_Onsite and 100 0.00 -
Offsite im ervious 98 _
~~ 0.17 - ____
Offsite o en 61 5.61 Assume ood condition
Offsite wooded 55 18.12 Assume good condition
Offsite nd 100 0.00 -
Total area = 32.51 acres
0.0508 sq.mi.
Composite SCS CN = 56
Impervious = 0.5%
•
B. Time of Concentration Information
The post-development time of concentration is equal to the pre-development time of concentration since this subbasin remains unaltered.
Time of Concentration = 22.89 minutes
SCS Lag Time = 13.73 minutes (SCS Lag = 0.6* Tc)
= 0.2289 hours
Time Increment = 3.98 minutes (= 0.29*SCS Lag)
•

HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 3C [DESIGN)
Cover Condition SCS CN Comments
-~ Im er~p_ vious~ 98 -
__ Open 6 ]
~ Assume good condition
Wooded 55 Assume good condition
II. POST DEVELOPMENT
_> Subbasin #3C - To SWMF #7
A. Watershed Breakdown

Phase
# Lots
Imp/Lot [sfl Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.21 0.21
1 B 0 3600 0.00 0.00 0.00
2 9.5 4000 0.87 8.80 9.67
3 14 4000 1.29 1.28 2.57
___m-__m 4 0 _
4000 0.00 0.00 0.00
*Other Impervious includes Impervious from L'ownhomes, (ireenway lraus, ana ntgnt-of-rvay
•
Contributing Area SCS CN Area [acres) Comments
Onsite im ervious 98 12.45 -
Onsite open
Onsite wooded 61
55 11.75
0.00 _ Assume good condition
Assume ood condition
Onsite and 100 0.68 -
Offsite impervious 98
_ _0.01_ -
_ Offsite open _
_ 61
_ _2.24 _ Assume good condition
Offsite wooded 55 4.54 Assume good condition
Offsite and 100 0.00 -
Total area = 31.67 acres
0.0495 sq.mi.
Composite SCS CN = 76
Impervious = 39.3%
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)
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development -Subbasin 3C [DESIGN) 6/14/2007
• _> Subbasin #3C -Bypass
A. Watershed Breakdown
Contributing Area SCS CN Area (acres] Comments
Onsite im ervious 98 4.07 -
_ Onsite~en ~ 61 21.83 Assume good condition
Onsite wooded
Onsite and 55
100 __ _34.02_
1.43 Assume good condition
-
Offsite im ervious 98 0.00 -
_ Offsite open
Offsite wooded __ _ 61
55 ~ 0.11_
0.48 _Ass_um_e food condition
Assume ood condition
Offsite and 100 0.00 -
•
acres
sq.mi.
Segment 2: Concentrated Flow
ft Length = 241 ft
ft Height = 19 ft
ft/ft Slope = 0.0788 ft/ft
Dense grasses Paved ? = No
inches (Raleigh, NC) Velocity= 4.53 ft/sec
minutes Segment Time = 11.$9 minutes
Segment 4: Channel Flow
ft Length = 1396 ft
ft Height = 35 ft
ft/ft Slope = 0.0251 ft/ft
Natural Channel Manning's n = 0.045 Natural Channel
sf (Assume 2' x 2' Channel) Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
ft (Assume 2' x 2' Channel) Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel)
ft/sec Channel Velocity = 4.64 R/sec
minutes Segment Time = S.DI minutes
ft
ft
ft/ft
Natural Channel
sf (Assume 5' x 5' Channel)
ft (Assume 5' x 5' Channel)
ft/sec
minutes
Time of Concentration = 22.08 minutes
SCS Lag Time = 13.25 minutes (SCS Lag = 0.6* Tc)
= 0.2208 hours
Time Increment = 3.84 minutes (= 0.29*SCS Lag)
Total area = 61.94
0.0968
Composite SCS CN = 61
Impervious = 6.6%
B. Time of Concentration Information
Segment 1: Overland Flow
Length = 100
Height = 4
Slope = 0.0400
Manning's n = 0.24
P (2-year/24-hour) = 3.6
Segment Time = 1 t1.?0
Segment 3: Channel Flow
Length = 372
Height = 16
Slope = 0.0430
Manning's n = 0.045
Flow Area = 4.00
Wetted Perimeter = 6.00
Channel Velocity = x.24
Segment Time = 1.1.4
Segment 5: Channel Flow
Length = 1293
Height = 12
Slope = 0.0093
Manning's n = 0.045
Flow Area = 25.00
Wetted Perimeter= 15.00
Channel Velocity = 4.48
Segment Time = d.81
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin 3C [ACTUAL] 6/14/2007
•
I. SCS CURVE NUMBERS
Cover Condition SCS CN Comments
Im rvious 98 -
_-Open 61 Assume good condition
Wooded 55 Assume good condition
II. POST DEVELOPMENT
_> Subbasin #3C - To SWMF #7

Phase
# Lots
Imp/Lot Est] Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.21 0.21
1 B 0 3600 0.00 0.00
T 0.00
2 9.5 ~ 4000 0.87 8.80 9.67
3 0 4000 0.00 0.52
~ 0.52
~^
_
~~ 4 ~0 4000 0.00 0.00 0.00
'Other tmperv[ous includes [mpervious)rom t ownhomes, vreenway t raus, ana rcrgnr-o~-rray
Contributing Area SCS CN Area ~acresJ Comments
Onsite im ervious 98 10.40
____ Onsite open ~
Onsite wooded _ 61
55 9.47
0.00 _ Assume flood condition
Assume good condition
Onsite and 100 0.68 -
OfI'site im_ e~rvious _98 _ 0.00 _ - _ ____
_ Offsite oRen ~ 61
~ _1.66
~ Assume food condition
Offsite wooded 55 3.51 Assume good condition
Offsite and 100 0.00 -
• Total area = 25.72 acres
0.0402 sq.mi.
Composite SCS CN = 76
Impervious = 40.4%
B. Time of Concentration Information
The post development time of concentration is assumed to be 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)
A. Watershed Breakdown
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development -Subbasin 3C (ACTUAL) 6/14/2007
• _> Subbasin #3C -Bypass
A. Watershed Breakdown
Contributing Area SCS CN Area nacres) Comments
_Onsite im ervious 98 4.20 -
Onsite ~n
Onsite wooded
Onsite and
~ 61
55
100 23.21
36.85
1.43 Assum~ood condition
Assum~ood condition __
-
Offsite im ervious 98 0.01 -
Offsite~en 61 _
_____
~ _ 0.6_8_ _ Ass_u~ood condition
Offsite wooded 55 1.51 Assume ood condition
Offsite and 100 0.00 -
•
acres
sq.mi.
Segment 2: Concentrated Flow
ft Length = 167 ft
ft Height = 14 ft
ft/ft Slope = 0.0838 ft/ft
Dense grasses Paved ? = No
inches (Raleigh, NC) Velocity = 4.67 ft/sec
minutes Segment Time = O.G(I minutes
Segment 4: Channel Flow
ft Length = 1396 ft
ft Height = 35 ft
ft/ft Slope = 0.0251 ft/ft
Natural Channel Manning's n = 0.045 Natural Channel
sf (Assume 2' x 2' Channel) Flow Area = 6.25 sf (Assume 2.5' x 2.5' Channel)
ft (Assume 2' x 2' Channel) Wetted Perimeter = 7.50 ft (Assume 2.5' x 2.5' Channel)
ft/sec Channel Velocity = 4.64 ft/sec
minutes Segment Time = 5.01 minutes
ft
ft
ft/ft
Natural Channel
sf (Assume 5' x 5' Channel)
ft (Assume 5' x 5' Channel)
ft/sec
minutes
Time of Concentration = 20.38 minutes
SCS Lag Time = 12.23 minutes (SCS Lag = 0.6* Tc)
= 0.2038 hours
Time Increment = 3.55 minutes (= 0.29*SCS Lag)
Total area = 67.89
0.1061
Composite SCS CN = 61
Impervious = 6.2%
B. Time of Concentration Information
Segment l: Overland Flow
Length = 100
Height = 8
Slope = 0.0800
Manning's n = 0.24
P (2-year/24-hour) = 3.6
Segment Time = ' '3
Segment 3: Channel Flow
Length = 642
Height = 23
Slope = 0.0358
Manning's n = 0.045
Flow Area = 4.00
Wetted Perimeter = 6.00
Channel Velocity= 4.7s?
Segment Time = '.?4
Segment 5: Channel Flow
Length = 1293
Height = 12
Slope = 0.0093
Manning's n = 0.045
Flow Area = 25.00
Wetted Perimeter = 15.00
Channel Velocity = 4.48
Segment Time = 4.$1
•

•
l1. POST DEVELOPMENT
_> Subbasin #4A - To SWMF #10
A. Watershed Breakdown

Phase
# Lots
Imp/Lot ~sfJ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.00 0.00
^_ 1B _0
~ 3600 0.00 0.00 0.00
2 95 _
_
4000 T 8.72 4.25 12.97
_ 3 _ _
~ 11.5 4000 _ 1.06 0.04 1.10

4
0
4000
0.00
u 0.00 _
0.00
'Utherlmpervwus includes /mperviousJrom lownhomes, Greenway Trails, and Kight-oJ-Way
•
Total area = 26.85 acres
0.0420 sq.mi.
Composite SCS CN = 81
Impervious = 52.4%
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
HIGHLAND CREEK
CTX-06070
I. SCS CURVE NUMBERS
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 4A
Cover Condition SCS CN Comments
_ _hnp_ervious 98
~ _ - _
~
----Open __ 61
_____ Assume good condition-
Wooded 55 Assume good condition
Contributing Area SCS CN Area [acres) Comments
Onsite im ervious 98 14.07 -
Onsite open
_---_
Onsite wooded 61
___-------..
55 12.13
_....~__.._........_...._
0.00 _ .Assume good condition

Assume ood condition
g
Onsite and 100 0.65 -
_Offsite impervious
__ Offsite o~en_~ _ 98 ~
~ 61 _~ _ 0.00_ _
0.00 v __M~ - _~
Assume food condition
Offsite wooded 55 0.00 Assume oodood cow
Offsite and 100 0.00 ___, -
•

•
_> Subbasin #4A -Bypass
A. Watershed Breakdown
HYDROLOGIC CALCULATIONS
Post Development - Subbasin 4A

Phase
# Lots
Imp/Lot JsfJ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.00 0.00
1 B _ 0 __
~
~ 3600 0.00 0.00 0.00

2
__-_.
3 _ ~
4000
0.28
T 0.02 _~
0.30

3
~__. _ __
..._._._
0
----.
-
4000
0.00
0.00 _
0.00
4 ~ 4000 ~ 0.00 ~ _
0.00 -~ ~ 0.00 ____
-vmer impervious mc[uaes tmperv~ous from townnomes, Cireenway [rails, and tttght-oj-way
Contributing Area SCS CN Area JacresJ Comments
Onsite im ervious 98 0.30 -
_Onsite open ~v 61 _ 105 ~' Assume food condition
Onsite wooded 55 1.14 Assume ood condition
Onsite and 100 0.00 -
_Offsite impervious _.
Offsite open__ _
Offsite wooded ._._. 98_____.
61
55 .__ 0.2~._,~ ..
2.27
0.54 _._..-_ __.- _ -
Assume good condition
Assume flood condition
Offsite and 100 0.00 -
•
Total area = 5.50 acres
0.0086 sq.mi.
Composite SCS CN = 63
Impervious = 9.0%
B. Time of Concentration Information
Segment l: Overland Flow
Length = 100 ft
Height = 5 ft
Slope = 0.0500 ft/ft
Manning's n = 0.24 Dense grasses
P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = 9.33 minutes
Segment 3: Channel Flow
Length = 409 ft
Height = 13 ft
Slope = 0.0318 ft/ft
Manning's n = 0.045 Natural Channel
Flow Area = 4.00 sf (Assume 2' x 2' Channel)
Wetted Perimeter = 6.00 ft (Assume 2' x 2' Channel)
Channel Velocity = 4.50 ft/sec
Segment Time = 1. ~ 1 minutes
Segment 2: Concentrated Flow
Length = 506 ft
Height = 28 ft
Slope = 0.0553 ft/ft
Paved ? = No
Velocity = ?.80 ft/sec
Segment Time = 2.21 minutes
J. ALDRIDGE, EI
6/] 4/2007
Time of Concentration = 13.06 minutes
SCS Lag Time = 7.84 minutes (SCS Lag = 0.6* Tc)
= 0.1306 hours
Time Increment = 2.27 minutes (= 0.29*SCS Lag)
HIGHLAND CREEK
CTX-06070
•

•
II. POST. DEVELOPMENT
__> Subbasin #4B
A. Watershed Breakdown

Phase
# Lots
Imp/Lot (sfl Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.00 0.00
1 B 0 3600 0.00 0.00 0.00
2 ~0 T ~, m 4000 0.00 0.02 0.02
_
__ 3
~ ~
~~ 0 4000 0.00 0.00 0.00
4 ____ 0 4000 0.00 0.00 0.00
'Other [mperv[ous mc[udes [mperviousJrom lbwnhomes, Greenway [Taus, and Kight-oJ-way
Contributing Area SCS CN Area ~acres~ Comments
Onsite im ervious 98 0.02
_ _ Onsite own _ 61 _ _
~~ __ _0.28 _ _ Assume good condition
Onsite wooded 55 0.02 Assume ood condition
Onsite and 100 0.00
Offsite impervious _ 98 _ 0.00 ~ - __
Offsite~en
~ 61 _
~ ~ 0.00__ __ _Assume og od condition
Offsite wooded 55 0.00 Assume good condition
Offsite and 100 0.00 -
•
Total area = 0.32 acres
0.0005 sq.mi.
Composite SCS CN = 63
Impervious = 6.3%
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
HIGHLAND CREE',K
CTX-06070
t: 5CS CURYENI7~1BLRS
HYDROLOGIC CALCULATIONS
Post Development - Subbasin 4B
Cover Condition SCS CN Comments
Im ervious 98 -
w _O e~ n _ 61 Assume good condition
Wooded 55 Assume good condition
•

It. F'OST DEVELOPMENT"
__> Subbasin #4C
A. Watershed Breakdown

Phase
# Lots
Imp/Lot ~sfl Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 0.00 0.00
1B 0 3600 0.00 0.00
~ 0.00 _
^
_
_ _
~ w 2 _ __
~ 0 ~ _
_ 4000 _ A 0.00 0.06 0.06
3
4 0
0 4000
4000 0.00
0.00 0.00
0.00 0.00
0.00
'Utherlmpervious inc[udeslmpervious.lrom lownnomes. Greenway [Taus, ana tngnt-off-way
r~
Total area = 0.39 acres
0.0006 sq.mi.
Composite SCS CN = 67
Impervious = 15.4%
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
HIGHLAND CREEK
CTX-06070
L SCS CURVI: YGMBEIt,S
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 4C
Cover Condition SCS CN Comments
Impervious 98
~ __ - _,_
~
Open 61 Assume good condition __
_
Wooded _
_
55 Assume good condition
Contributing Area SCS CN Area nacres) Comments
Onsite im ervious 98 0.06 -
_ Onsite~en _ 61 __
~ _ 0.33
l
~~ Assum~dcondition
Onsite wooded 55 0.00 Assume ood condition
Onsite and 100 0.00 -
Offsite impervious 98 0.00 _ __~__-
_ __ Offsite opven _ _ 61
~ 0.00
_
v Assume good condition
Offsite wooded 55 0.00
~ Assume ood condition
Offsite and 100 0.00 -
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin S 6/14/2007
•
I. tics CUILVENUMBEIiS?
Cover Condition SCS CN Comments
Im 'ous 98
~_„__Open _71 Assume ood condition
Wooded 66 Assume ood condition
II. POST DEVELOI'11~F.N'I'
_> Subbasin #5 - To SWMF #1
A. Watershed Breakdown

Phase
# Lots
Imp/I.ot ~sfJ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
~~~ 1 ~__ 1.5
~
~ 3600 0.12 0.00 0.12
1 B 0 3600 _____ 0.00 _
~ 0.00 0.00
__ 2 _
_____ _ 9_3 _
_____
v 4000 8.54 2.95 11.49
3 0 4000 0.00 0.00 0.00
4 0 4000 0.00 0.00 0.00
vtner Impervious rnch~des lmpervmtis_/rom 7 ownnomes, tireenway 7 ratts, ana Kight-oJ-way
Contributing Area SCS CN Area ~acres~ Comments
Onsite i~rvious
~ _ 98 _
~ 11.61
~ _~
Onsite o en 71 10.63 Assume good condition
_ Onsite wooded _66_____
~ 0.00 Ass
ume p~ood condition
Onsite pond 100 0.56 _
Offsite impervious _ ~__ 98
~ _ 0.00_ ~___~ _ -__ _ _
~
Offsite o en 71 0.00 Assume ood condition
Offsite wooded
____
____
~ _66____ _ 0.00
~ _Assume ood condition
~
Offsite
nd 100 0.00 -
Total area = 22.80 acres
• 0.0356 sq.mi.
Composite SCS CN = 85
Impervious = 50.9%
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)
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin S 6/15/2007
• _> Subbasin #S - To SWMF #2
A. Watershed Breakdown

Phase
# Lots
Imp/Lot ~sfJ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
~_ 1
~ 1 3600 0.08 0.65 0.73
1B 0~ ~ 3600 ~ __
0.00 _
v 0.00 0.00

2
____.____ _3 V _. ~
0
~ 0 ~~
4_000_
~ 4000
_0.00
____ 0.00
_ 0.00__
~ 0.00 _
_ 0.00
0.00 ____
4 0 4000 0.00 5.98 5.98
`vtner tmpervrous rnc[uaes tmpernous~rom [ownnomes, tireenway trar[s, and Krgnt-off-way
Contributing Area SCS CN Area (acres Comments
Onsite impervious
Onsite o en _ __ 98 _
71 m.. 6.71
4.52 -
Assume ood condition
_ Onsite wooded
Onsite nd _66 _
~ 100 ~ _ 0.00_
0.33 A_s_sume good condition__
_____ ~T
Otlsite impervious _ 98
~ 0.19 _
~ _ ~ _
_ a
Offsite o n 71 0.43 Assum
a good condition
~_Offsite wooded
Offsite nd 66
100 _ 0.00
0.00 ~ .
_ Assume good_condition_M
~~~ -
Total area = 12.18 acres
0.0190 sq.mi.
Composite SCS CN = 87
Impervious = 56.7%

B. Time of Concentration Information
71ie post development time ojconcentration is assumed to be 5 minuses
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)
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin 5 6/14/2007

_> Subbasin #5 - By ass
A. Watershed Breakdown

Phase
# Lots
Imp/Lot [sfl Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 1 3600 0.08 0.00 0.08
_
_
~~ IB ~ ~ __ __
_ __ _
0 3600 0.00 _
0.00 0.00
2 15 4000 1.38 0.06 1.44
3 0 4000 0.00 0.00 0.00
_______ 4 0 4000 0.00 0.63 0.63
•Utnerlmpervioustnc[udeslmperviousJrom lownhomes, Greenway~rails, andKight-oJ-Way
Contributing Area SCS CN Area [acres] Comments
Onsite irvious
~~ 98 2.15
~ _ _-~_
Onsite o n 71 7.62 Assume ood condition
Onsite wooded
Onsite and 66
100 3.51
0.00 Assume good condition _-
Offsite impervious
_ Offsite o n 98 _
~ 71 ~~ _0.00 _
0.00 ~ _ __ - __ _
Assume ood condition
Offsite wooded_ _ 66_ _
~ _0.00__ Assume ood condition
~~
~~
Offsite nd 100 0.00 -
Total area = 13.28 acres
0.0208 sq.mi.
Composite SCS CN = 74
Impervious = 16.2%
B. Time of Concentration Information
• Segment 1: Overland Flow
Length = 100
Height = 3.5
Slope = 0.0350
Manning's n = 0.24
P (2-year/24-hour) = 3.6
Segment Tinte = 111J(i
Segment 3: Channel Flow
Length = 1443
Height = 53
Slope = 0.0367
Manning's n = 0.045
Flow Area = 4.00
Wetted Perimeter = 6.00
Channel Velocity = 4.81
Segment Time = a.9i'
ft
ft
ft/ft
Dense grasses
inches (Raleigh, NC)
minutes
ft
ft
ft/ft
Natural Channel
sf (Assume 2' x 2' Channel)
ft (Assume 2' x 2' Channel)
ft/sec
minutes
Segment 2: Concentrated Flow
Length = l99 ft
Height = 17 ft
Slope = 0.0854 ft/ft
Paved ? = No
Velocity= 4.72 ft/sec
Segment Time = !l. ?tl minutes
Time of Concentration = ]6.43 minutes
SCS Lag Time = 9.86 minutes (SCS Lag = 0.6* Tc)
= 0.1643 hours
Time Increment = 2.86 minutes (= 0.29*SCS Lag)
•

HIGHLAND CREEK
CTX-06070
I. SCS Cl:l-iVI: VUII~IBERS
HYDROLOGIC CALCULATIONS
Post Development - Subbasin 6A
Cover Condition SCS CN Comments
_ Impervious,,,, ____ 98 _ __ ______ -
en 61 Assume ood condition
Wooded 55 Assume good condition
Il. YOST DEVELOPME1r f
_> Subbasin #6A
A. Watershed Breakdown
J. ALDRIlX'iE, EI
6/14/2007
Contributing Area SCS CN Area [acres) Comments
e impervious
Onsit 98 0.00
______
Onsite open _
~~ 61 ~_ 0.00 Assum~od condition
Onsite wooded 55 0.00 Assume ood condition
~~ Onsite and 100 0.00 -
Offsite impervious
_ Offsite o.Pei1_.__...__
Offsite wooded 98
__........_.___61 _.......____..
55 13.71
...._....._1.13.76 __
134.70 -
_Assume good condition.__.._..
Assume ood condition
Offsite and 100 3.38 -
Total area = 265.55 acres
0.4149 sq.mi.
Composite SCS CN = 60
Impervious = 5.2%
•
B. Time of Concentration Information
The post-development time of concentration is equal to the pre-development time of concentration since this subbasin remains unaltered.
Time of Concentration = 23.93 minutes
SCS Lag Time = 14.36 minutes (SCS Lag = 0.6* Tc)
= 0.2393 hours
Time Increment = 4.16 minutes (= 0.29*SCS Lag)
•

•
HIGHLAND CREEK
CTX-06070
I. SC5 CARVE ~URIBERS ~,
HYDROLOGIC CALCULATIONS
Post Development -Subbasin tiB
Cover Condition SCS CN Comments
~Im_~ervious _ 98 _._._ . - _ _
w Open ~ _ _ 61 _ Assume good condition __
Wooded 55 ___Assume good condition
II. POS'1~ DI;VI;LOP~II:YT
_> Subbasin #6B
A. Watershed Breakdown
J. ALDRIDGE, EI
6/14/2007
Contributing Area SCS CN Area (acres) Comments
Onsite imperviou_s_ _98
~ 0.00 _ -
Onsite o en 61 0.00 Assume ood condition
_Onsite wooded 55 0.00 _
_~_ Assume og._od_condition
__
__,_
__-_..___Onsitepond._.._._..
Offsite im ervious ...._.._.100......_......__
98 _._._._0.:._00 __
3.07 .___...__.....__....__._: __.__ ._
-
Offsite o en 61 24.71 Assume ood condition
Offsite wooded
y 55 __5_8.24 Assume good condition ~.
~~
Offsite and 100 0.16 -
Total area = 86.18 acres
0.1347 sq.mi.
Composite SCS CN = 58
Impervious = 3.6%
r~
B. Time of Concentration Information
The post-development time of concentration is equal to the pre-development time of concentration since this subbasin remains unaltered.
Time of Concentration = 32.08 minutes
SCS Lag Time = 19.25 minutes (SCS Lag = 0.6* Tc)
= 0.3208 hours
Time Increment = 5.58 minutes (= 0.29*SCS Lag)
:7

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin 6C 6/14/2007
1. SCS CURVE NUi17BER5
• Cover Condition SCS CN Comments
Im~rvious 98 ~ -

____ Open _ __ ~
_ ~ 61__-_ _. t._._--__-----._~_~~~_.__
__~_~Assume~ood condition
Wooded 55 Assume good condition
^. POSTDEVELOPJIEN7'
_> Subbasin #6C - To SWMF #3
A. Watershed Breakdown
•

Phase
# Lots j Imp/Lot [sf) Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 0 3600 0.00 1.20 __ 1.20
.__ ~_ ~ 13 _____._. _ ______ 0 _. _ _ - 3600 _ ~ 0.00 2.55 2.55
2 0 4000 0.00 0.00 0.00
3 4000
0 ~ 0.00
~ 0.00
~ 0.00
~
_
_
~~ ~~ 4 ~~ _
~~ 0 4000 ~ _
0.00 0.00 0.00
'Utner/mpervtous mc[udes Impervious7rom 7bwnhomes, vreenway [Taus, aria tagnt-o7-way
Contributing Area SCS CN ~ Area [acres[ Comments
Onsite impervious 98 3.75 -
Onsite o en 61 i 4.21 Assume ood condition
Onsite wooded 55 0.00 Assume ood condition
Onsite and 100 0.44 -
Offsite im ervious 98 2.71 -
OlI'site o en 61 10.11 Assume ood condition
Offsite wooded 55 7.50 Assume ood condition
Offsite and 100 0.00 -
Total area = 28.72 acres
0.0449 sq.mi.
Composite SCS CN = 68
Impervious = 22.5%
B. Time of Concentration Information
The post development time of concentration is assumed to be S 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)
•

HIGHLAND CREEK
CTX-06070
_> Subbasin #6C- To SWMF #4
A. Watershed Breakdown
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 6C

Phase ~
# Lots ~
Imp/Lot [sf) Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
] 27.5 3600 2.27 9.72 11.99
1B 0 3600 0.00 0.00 0.00
2 0 4000 _ 0.00 0.00 0.00
3 0 ~ ~
4000 0.00 0.00 _0.00
_
~~4 v ____ 0 _
~ 4000 0.00 0.00 0.00
'Other Impervious includes /mpervtous Jrom I bwnhomes, cireenway / raUS, ana t<ignt-oJ-way
Contributing Area SCS CN Area [acres) Comments
Onsite im ervious 98 11.99 -
Onsite o en 61 9.45 Assume good condition
Onsite wooded 55 0.00 Assume ood condition
Onsite and 100 0.46 -
Offsite im ervious 98 0.00 -
Oflsite o en 61 0.00 Assume ood condition
Offsite wooded 55 0.00 Assume good condition
______
Offsite and ____ 100 ~ 0.00 ~~ -
Total area = 21.90 acres
0.0342 sq.mi.
Composite SCS CN = 82
Impervious = 54.8%
r~
B. Time of Concentration Information
The post development time of concerttratiat is assumed to be 5 minutes
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCSLag = 0.6* Tc)
= 0.0500 hours
Time Increment = 0.87 minutes (= 0.29*SCS Lag)
J. ALDRIDGE, EI
6/14/2007
•

•
HIGHLAND CREEK
CTX-06070
_> Subbasin #6C - To SWMF #5
A. Watershed Breakdown
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 6C

Phase
# Lots
Imp/Lot [st] Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 60 3600 4.96 2.64 7.60
1B 0 3600 0.00 0.00 0.00
2 0 4000 0.00 0.00
~ 0.00
____ 3 ___ 0
~ 4000 0.00 0.00
v' 0.00 _
~~ 4 _
0 4000 0.00 0.00 0.00
*Other Impervious includes Impervioi~.s from Townhomes, Greertway Trails, and Right-of-Way
Contributing Area SCS CN Area ~acres~ Comments
O_ nsite impervious
Onsite open _ 98 ~ 7.60
61 __ _ 7.27
~
~ _ - _ _ ,_~
Assume good condition
~Onsite wooded 55
0.00 Assume good condition
Onsitee fond 100 _ 0.33
~
~ _ ___- _ ,~~
Offsite i~ervious
Offsite o n 0.00
98
61 0.00 _- _
Assume good condition
Oflsite wooded _55 ? 0.00 Assume~ood condition
v
__
Offsite nd 100 0.00 -
Total area = 15.20 acres
0.0237 sq.mi.
Composite SCS CN = 80
Impervious = 50.0%
•
B. Time of Concentration Information
The post development time of concentration is assumed to be 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)
J. ALDRIDGE, EI
6/14/2007
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development -Subbasin 6C 6/15/2007
• _> Subbasin #6C- To SWMF #6
A. Watershed Breakdown

Phase
# Lots ~ Imp/Lot ~sq
` Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
] 37.5 3600 3.10 3.11 6.21
I B 0 i 3600 0.00
~~ 0.00 0.00
2 0 4000
~ 0.00
____.
~ 0.00 0.00
_
_
____ 3 ~.. ~
_
~~ _
4000 ~
0~
a___________ 0.00

~ 0.00

____ 0.00

v
4 0 3 4000 0.00 0.00 0.00
'Utherlmpervtous mauaes tmpervrousJrom lownnomes, vreeewuy ~ ruus, unu nrgnr~~-..uy

Contributing Area SCS CN I Area nacres] Comments
Onsite impervious 98 __ ~ 6.21
~ _____ - _ _ _
Onsite o en
_..._........_.....__.__...p..........----...... ~ ~
61
.._.._....______..._..._.. 6.67
_ ~
_..._............_._...____....__... Assume ood condition
._.........._..._..._._.._....~.. __ ._._.._.__
Onsite wooded 55 's, 0.00 Assume _pood condition
Onsite pond 100 ~ 0.32
............._..........
. -
_..___---_.....__._._......._....__._....___._....._~.....
. _
__.....__....
__Offsiteimpervious.._. _.....
~.~...~._._
__......__._98__._._ ......r ...............
..
_' .. .._0.00 ................
___.._ -
Offsite open 6] 0.13
__. Assume good condition
_
___ _
Offsite wooded ~
~
55 r ~._. _ ___
0.52 Assume good condition
Offsite nd 100 0.00 -
Total area = 13.85 acres
0.0216 sq.mi.
Composite SCS CN = 78
Impervious = 44.8%
B. Time of Concentration Information
The post development time of concentration is assumed to be 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 La
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development - Subbasin 6C 6/14/2007
• _> Subbasin #6C -Bypass
A. Watershed Breakdown

Phase
# Lots
Imp/Lot ~sfl Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 28.5 3600 2.36 2.20 4.56
1 B 0 E 3600 0.00 0.00 0.00
2 0 4000 0.00_
~ 0.00
~m 0.00
3
4 _ _ 0 _
OW ~ ___ 4000 _ _
4000 ~ 0.00 _
_
0.00 0.00
0.00 0.00
0.00
*Other Impervious includes Impervious from 7ownhomes, Greenway [Taus, ana rcignt-o~-rvay
Contributing Area SCS CN ~ Area (acres Comments
Onsite im ervious 98 4.56 -
Onsite o en 61 12.97 Assume ood condition
Onsite wooded 55 7.98 Assume ood condition
Onsite nd 100 1.17 -
OII'site im envious 98 0.03 -
Offsite o en 61 3.45 Assume ood condition
Offsite wooded _
Offsite and ~ 55 _
100 2.09
€ 0.00 .Assume ood condition
-
•
acres
sq.mi.
Segment 2: Concentrated Flow
8 Length = 23 ft
ft Height = 1.3 ft
ft/ft Slope = 0.0565 ft/ft
Dense grasses Paved ? = No
inches (Raleigh, NC) Velocity = 3.83 ft/sec
minutes Segment Time = D.10 minutes
Segment 4: Cban nel Flow
ft Length = 1146 ft
ft Height = 10 ft
ft/ft Slope = 0.0087 ft/ft
Natural Channel Manning's n = 0.045 Natural Channel
sf (Assume 3' x 3' Channel) Flow Area = 36.00 sf (Assume 6' x 6' Channel)
ft (Assume 3' x 3' Channel) Wetted Perimeter = 18.00 ft (Assume 6' x 6' Channel)
ft/sec Channel Velocity= 491 ft/sec
minutes Segment Time = 3.89 minutes
Segment Time = Z84
Time of Concentration = 19.04 minutes
SCS Lag Time = 11.42 minutes (SCS Lag = 0.6* Tc)
= 0.1904 hours
Time Increment = 3.31 minutes (= 0.29*SCS Lag)
Total area = 32.25
0.0504
Composite SCS CN = 66
Impervious = 14.2%
B. Time of Concentration Inform ation
Segment 1: Overland Flow
Length = 100
Height = 9.5
Slope = 0.0950
Manning's n = 0.24
P (2-year/24-hour) = 3.6
Segment Time = ,'.2l
Segment 3: Channel Flow
Length = 2297
Height = 50
Slope = 0.0218
Manning's n = 0.045
Flow Area = 9.00
Wetted Perimeter = 9.00
Channel Velocity= •1.89
•

L
Il. P051~ D~~'ELOPMF:NT
_> Subbasin #7
A. Watershed Breakdown

Phase
# Lots
Imp/Lot JsfJ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1 1 3600 0.08 0.40 0.48
1B 0 3600 0.00 0.00 0.00
_
______
2 _
_
~0 ~ 4000 0.00 0.00 0.00
3 0 4000 0.00 0.00 0.00
4 _
~ 0~ _
4000 0.00 0.00 0.00
'Other Impervious inc[udeslmperviousjrom Ibwnhomes, (ireenway !rails, and !tight-oJ-Way
•
HIGHLAND CREEK
CTX-06070
I. scs cui~v>~ NUIIIBT< ]?s
HYDROLOGIC CALCULATIONS
Post Development - Subbasin 7
Cover Condition SCS CN Comments
hn ervious
~ 98 _ -
_ Open 61 Assume good condition
Wooded 55 Assume good condition
Contributing Area SCS CN Area JacresJ Comments
Onsite im ervious 98 0.48 -
__- Onsite open
Onsite wooded 61
55 ~ 0.56
0.34 Assume mood condition
Assume ood condition
Onsite and 100 0.00 -
_Offsite impervious
_Offsite o en _~ 98 ~
~ 61 ~ _ 0.00 _
0.00 _
____ -_
~~ Assume ood condition
Offsite wooded 55 0.19 Assume ood condition
Offsite and 100 0.00 -
Total area = 1.57 acres
0.0025 sq.mi.
Composite SCS CN = 70
Impervious = 30.7%
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
•

•
HIGHLAND CREEK
CTX-06070
J;SCSGI7RV~ NUMBEti,S
HYDROLOGIC CALCULATIONS
Post Development -Subbasin 8
Cover Condition SCS CN Comments
Impervious ~ 98 -
_

O n
61 _
^
Assume good condition
Wooded 55 Assume good condition
II. POST DE,~~El~P11E1~I'
_> Subbasin #8
A. Watershed Breakdown
Contributing Area SCS CN Area [acres[ Comments
_ Onsite impervious 98_
~ 0.00 -
Onsite o en 61 0.26 Assume flood condition
Onsite wooded_ 55 0.00 ~_ Assume good condition
~
_ Onsite~ond__, _ 100 ~
_ _ 0.00
____ ___
~~_________
Offsite im ervious 98 0.00 -
Offsite o en 61 0.00 Assume ood condition
Offsite wooded
~ 55 __ 0.00
~ A_ ssume good condition
v
Offsite and 100 0.00 -
Total area = 0.26 acres
0.0004 sq.mi.
Composite SCS CN = 61
Impervious = 0.0%
•
B. Time of Concentration Information
The post development time of concentration is assumed to be 5 minutes
J. ALDRIDGE, EI
6/14/2007
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)
•

HIGHLAND CREEK CALCULATION OF REACH LAG TIMES J. ALDRIDGE, EI
CTX-04020 Post-Development 5/2/2007

*Lag times are calculated assuming a S-ft/sec velocity.
T = (L / V) *(1 minute / 60 seconds)
Where:
T = Lag Time (min)
L = Reach Length (ft)
V = Flow Velocity (ft/sec)
ap.; ~ ~: ~; :M-
•
Reach Length [feet] Lag Time
minutes
1 1143 3.81
.
2 1587 _„y _
5.29
3
___.___..._~__.
4 1289 _
_.__._.._~_____
2317 ~~ 4 30 ~..,,._~_
_.n__~.._____~___~._~___
7.72 ~^
5 1322 4.41
~~
_
6 _2663 8.88
~_.____
~~~-
______ 7 !
8
~ 2279
1252 ~7.60
417 _ ___
_____
9' __
~' 1938 6.46
•

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HMS * Summary of Results
Project CTX-06070 Run Name POST [DESIGN] - Q2
• Start of Run 16Feb07 0800 Basin Model POST [DESIGN]
End of Run 17Feb07 0800 Met. Model Q2
Execution Time 29Jun07 0947 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 5 - SWMF #1 84.656 16 Feb 07 2004 3.9875 0.036
SWMF #1 0.51341 17 Feb 07 0800 0.50897 0.036
Sub 5 - SWMF #2 48.634 16 Feb 07 2004 2.2991 0.019
SWMF #2 0.52552 17 Feb 07 0250 0.32878 0.019
Sub 5 - Bypass 20.737 16 Feb 07 2012 1.4459 0.021
Subbasin 5 21.304 16 Feb 07 2012 2.2837 0.075
Subbasin 1 7.2806 16 Feb 07 2005 0.34450 0.004
Subbasin 2 2.6332 16 Feb 07 2015 0.28884 0.013
Sub 3C - To SWMF #7 79.810 16 Feb 07 2005 3.7893 0.050
SWMF #7 22.261 16 Feb 07 2018 2.6967 0.050
Reach 9 22.261 16 Feb 07 2024 2.6906 0.050
Subbasin 8 0.21956 16 Feb 07 2006 0.013151 0.000
Reach 4 0.21956 16 Feb 07 2013 0.013116 0.000
b 6C - To SWMF #6 38.341 16 Feb 07 2005 1.8094 0.022
F #6 0.21635 17 Feb 07 0800 0.20610 0.022
ub 6C - To SWMF #5 46.019 16 Feb 07 2005 2.1650 0.024
SWMF #5 0.23396 17 Feb 07 0800 0.22476 0.024
Reach B 0.23387 17 Feb 07 0600 0.22347 0.024
Sub 6C - To SWMF #4 72.218 16 Feb 07 2005 3.3965 0.034
SWMF #4 0.60525 17 Feb 07 0650 0.28732 0.034
Reach 7 0.60525 17 Feb 07 0657 0.28183 0.034
Sub 6C - To SWMF #3 45.204 16 Feb 07 2005 2.2929 0.045
SWMF #3 1.7023 16 Feb 07 2306 0.72322 0.045
Reach 6 1.7023 16 Feb 07 2314 0.71737 0.045
Subbasin 7 2.8776 16 Feb 07 2005 0.14238 0.003
Reach 1 2.8776 16 Feb 07 2008 0.14225 0.003
Subbasin 6A 112.56 16 Feb 07 2021 12.613 0.915
Junction 1 113.47 16 Feb 07 2020 12.755 0.417
Reach 2 113.47 16 Feb 07 2025 12.730 0.417
Subbasin 6B 24.419 16 Feb 07 2028 3.4978 0.135
Sub 6C - Bypass 27.565 16 Feb 07 2015 2.2845 0.050
Junction 2 156.92 16 Feb 07 2025 19.941 0.727
Reach3 156.92 16 Feb 07 2029 19.903 0.727
Subbasin 3A 17.135 16 Feb 07 2020 2.1805 0.099
Junction 3 170.57 16 Feb 07 2028 22.096 0.826
Reach 5 170.57 16 Feb 07 2032 22.054 0.826
Sub 3C - Bypass 30.680 16 Feb 07 2019 3.1664 0.097
bbasin 3B 8.2831 16 Feb 07 2022 1.1167 0.051
~
nction 4 216.45 16 Feb 07 2031 29.028 1.024
Sub 4A - SWMF #10 85.106 16 Feb 07 2005 4.0019 0.042
SWMF #10 0.48941 17 Feb 07 0800 0.47276 0.042

Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
4A - Bypass 4.2950 16 Feb 07 2011 0.32348 0.009
basin 4A 4.6526 16 Feb 07 2012 0.79624 0.051
Subbasin 4B 0.33427 16 Feb 07 2006 0.018850 0.001
Subbasin 4C 0.56185 16 Feb 07 2005 0.028945 0.001
•
•
Page: 2

HMS * Summary of Results
Project CTX-06070 Run Name POST [DESIGN] - Q10
• Start of Run 16Feb07 0800 Basin Model POST [DESIGN]
End of Run 17Feb07 0800 Met. Model Q10
Execution Time 29Jun07 0948 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 5 - SWMF #1 124.94 16 Feb 07 2004 7.0537 0.036
SWMF #1 20.422 16 Feb 07 2030 3.4514 0.036
Sub 5 - SWMF #2 69.746 16 Feb 07 2004 3.9728 0.019
SWMF #2 15.176 16 Feb 07 2022 1.9982 0.019
Sub 5 - Bypass 38.352 16 Feb 07 2012 2.9508 0.021
Subbasin 5 57.722 16 Feb 07 2020 8.4005 0.075
Subbasin 1 12.113 16 Feb 07 2005 0.67393 0.004
Subbasin 2 10.262 16 Feb 07 2012 0.86413 0.013
Sub 3C - To SWMF #7 135.18 16 Feb 07 2005 7.5150 0.050
SWMF #7 85.444 16 Feb 07 2010 6.4046 0.050
Reach 9 65.444 16 Feb 07 2016 6.3936 0.050
Subbasin 8 0.56171 16 Feb 07 2005 0.034109 0.000
Reach 4 0.58171 16 Feb 07 2012 0.034034 0.000
b 6C - To SWMF #6 62.730 16 Feb 07 2004 3.4926 0.022
F #6 6.6726 16 Feb 07 2035 1.5959 0.022
ub 6C - To SWMF #5 73.026 16 Feb 07 2004 4.0718 0.024
SWMF #5 10.730 16 Feb 07 2032 1.9043 0.024
Reach 8 10.730 16 Feb 07 2036 1.9007 0.024
Sub 6C - To SWMF #4 111.35 16 Feb 07 2004 6.2298 0.034
SWMF #4 20.876 16 Feb 07 2026 3.1129 0.034
Reach 7 20.876 16 Feb 07 2033 3.1034 0.034
Sub 6C - To SWMF #3 91.660 16 Feb 07 2005 5.1486 0.045
SWMF #3 34.584 16 Feb 07 2017 3.5704 0.045
Reach 6 34.564 16 Feb 07 2025 3.5589 0.045
Subbasin 7 5.5321 16 Feb 07 2005 0.30901 0.003
Reach 1 5.5321 16 Feb 07 2008 0.30876 0.003
Subbasin 6A 339.79 16 Feb 07 2018 33.577 0.415
Junction 1 342.07 16 Feb 07 2018 33.886 0.417
Reach 2 342.07 16 Feb 07 2023 33.830 0.417
Subbasin 6B 83.464 16 Feb 07 2025 9.8423 0.135
Sub 6C - Bypass 63.141 16 Feb 07 2014 5.3241 0.050
Junction 2 515.48 16 Feb 07 2025 59.156 0.727
Reach3 515.48 16 Feb 07 2029 59.073 0.727
Subbasin 3A 67.114 16 Feb 07 2016 6.5264 0.099
Junction 3 561.45 16 Feb 07 2028 65.633 0.826
Reach 5 561.45 16 Feb 07 2032 65.591 0.826
Sub 3C - Bypass 87.485 16 Feb 07 2017 8.2196 0.097
basin 3B 32.434 16 Feb 07 2018 3.3430 0.051
ction 4 666.51 16 Feb 07 2030 83.497 1.024
Sub 4A - SWMF #10 133.10 16 Feb 07 2004 7.4320 0.042
SWMF #10 18.798 16 Feb 07 2033 3.6805 0.042

Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
4A - Bypass 10.798 16 Feb 07 2010 0.80145 0.009
basin 4A 22.357 16 Feb 07 2032 4.4819 0.051
Subbasin 4B 0.80979 16 Feb 07 2005 0.046684 0.001
Subbasin 4C 1.1737 16 Feb 07 2005 0.066173 0.001
•
•
Page: 2

HMS * Summary of Results
Project CTX-06070 Run Name POST [ACTUAL] - Q2
• Start of Run 16Feb07 0800 Basin Model POST [ACTUAL]
End of Run 17Feb07 0800 Met. Model Q2
Execution Time 29Jun07 1329 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 5 - SWMF #1 84.656 16 Feb 07 2004 3.9875 0.036
SWMF #1 0.51341 17 Feb 07 0800 0.50897 0.036
Sub 5 - SWMF #2 48.634 16 Feb 07 2004 2.2991 0.019
SWMF #2 0.52552 17 Feb 07 0250 0.32878 0.019
Sub 5 - Bypass 20.737 16 Feb 07 2012 1.4459 0.021
Subbasin 5 21.304 16 Feb 07 2012 2.2837 0.075
Subbasin 1 7.2806 16 Feb 07 2005 0.34450 0.004
Subbasin 2 2.6332 16 Feb 07 2015 0.28884 0.013
Sub 3C - To SWMF #7 64.815 16 Feb 07 2005 3.0774 0.040
SWMF #7 12.253 16 Feb 07 2024 1.9889 0.040
Reach 9 12.253 16 Feb 07 2030 1.9840 0.040
Subbasin 8 0.21956 16 Feb 07 2006 0.013151 0.000
Reach 4 0.21956 16 Feb 07 2013 0.013116 0.000
6C - To SWMF #6 38.341 16 Feb 07 2005 1.8094 0.022
~F #6 0.21635 17 Feb 07 0800 0.20610 0.022
Sub 6C - To SWMF #5 46.019 16 Feb 07 2005 2.1650 0.029
SWMF #5 0.23396 17 Feb 07 0800 0.22476 0.024
Reach 8 0.23387 17 Feb 07 0800 0.22347 0.024
Sub 6C - To SWMF #4 72.218 16 Feb 07 2005 3.3965 0.034
SWMF #4 0.60525 17 Feb 07 0650 0.28732 0.034
Reach 7 0.60525 17 Feb 07 0657 0.28183 0.034
Sub 6C - To SWMF #3 45.204 16 Feb 07 2005 2.2929 0.045
SWMF #3 1.7023 16 Feb 07 2306 0.72322 0.045
Reach 6 1.7023 16 Feb 07 2314 0.71737 0.045
Subbasin 7 2.8776 16 Feb 07 2005 0.14238 0.003
Reach 1 2.8776 16 Feb 07 2008 0.14225 0.003
Subbasin 6A 112.56 16 Feb 07 2021 12.613 0.415
Junction 1 113.47 16 Feb 07 2020 12.755 0.417
Reach 2 113.47 16 Feb 07 2025 12.730 0.417
Subbasin 6B 24.419 16 Feb 07 2028 3.9978 0.135
Sub 6C - Bypass 27.565 16 Feb 07 2015 2.2845 0.050
Junction 2 156.92 16 Feb 07 2025 19.941 0.727
Reach3 156.92 16 Feb 07 2029 19.903 0.727
Subbasin 3A 17.135 16 Feb 07 2020 2.1805 0.099
Junction 3 170.57 16 Feb 07 2028 22.096 0.826
Reach 5 170.57 16 Feb 07 2032 22.054 0.826
Sub 3C - Bypass 35.042 16 Feb 07 2017 3.4723 0.106
basin 3B 8.2831 16 Feb 07 2022 1.1167 0.051
nction 4 210.28 16 Feb 07 2031 28.627 1.023
Sub 4A - SWMF #10 85.106 16 Feb 07 2005 4.0019 0.042
SWMF #10 0.48941 17 Feb 07 0800 0.47276 0.042

Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
4A - Bypass 4.2950 16 Feb 07 2011 0.32348 0.009
basin 4A 4.6526 16 Feb 07 2012 0.79624 0.051
Subbasin 4B 0.33927 16 Feb 07 2006 0.018850 0.001
Subbasin 4C 0.56185 16 Feb 07 2005 0.028945 0.001
C
•
Page: 2

HMS * Summary of Results
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 29Jun07 1329
Run Name POST [ACTUAL] - Q10
Basin Model POST [ACTUAL]
Met. Model Q10
Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 5 - SWMF #1 124.94 16 Feb 07 2004 7.0537 0.036
SWMF #1 20.422 16 Feb 07 2030 3.4514 0.036
Sub 5 - SWMF #2 69.746 16 Feb 07 2004 3.9728 0.019
SWMF #2 15.176 16 Feb 07 2022 1.9982 0.019
Sub 5 - Bypass 38.352 16 Feb 07 2012 2.9508 0.021
Subbasin 5 57.722 16 Feb 07 2020 8.4005 0.075
Subbasin 1 12.113 16 Feb 07 2005 0.67393 0.004
Subbasin 2 10.262 16 Feb 07 2012 0.86413 0.013
Sub 3C - To SWMF #7 109.78 16 Feb 07 2005 6.1031 0.040
SWMF #7 64.928 16 Feb 07 2011 5.0002 0.040
Reach 9 64.928 16 Feb 07 2017 4.9913 0.040
Subbasin 8 0.58171 16 Feb 07 2005 0.034109 0.000
Reach 4 0.58171 16 Feb 07 2012 0.034034 0.000
6C - To SWMF #6 62.730 16 Feb 07 2004 3.4926 0.022
F #6 6.6726 16 Feb 07 2035 1.5959 0.022
ub 6C - To SWMF #5 73.026 16 Feb 07 2004 4.0718 0.024
SWMF #5 10.730 16 Feb 07 2032 1.9043 0.024
Reach 8 10.730 16 Feb 07 2036 1.9007 0.024
Sub 6C - To SWMF #4 111.35 16 Feb 07 2004 6.2298 0.034
SWMF #4 20.876 16 Feb 07 2026 3.1129 0.034
Reach 7 20.876 16 Feb 07 2033 3.1034 0.034
Sub 6C - To SWMF #3 91.660 16 Feb 07 2005 5.1486 0.045
SWMF #3 34.584 16 Feb 07 2017 3.5704 0.045
Reach 6 34.584 16 Feb 07 2025 3.5589 0.045
Subbasin 7 5.5321 16 Feb 07 2005 0.30901 0.003
Reach 1 5.5321 16 Feb 07 2008 0.30876 0.003
Subbasin 6A 339.79 16 Feb 07 2018 33.577 0.415
Junction 1 342.07 16 Feb 07 2018 33.886 0.417
Reach 2 342.07 16 Feb 07 2023 33.830 0.417
Subbasin 6B 83.484 16 Feb 07 2025 9.8423 0.135
Sub 6C - Bypass 63.141 16 Feb 07 2014 5.3241 0.050
Junction 2 515.48 16 Feb 07 2025 59.156 0.727
Reach3 515.48 16 Feb 07 2029 59.073 0.727
Subbasin 3A 67.114 16 Feb 07 2016 6.5264 0.099
Junction 3 561.45 16 Feb 07 2028 65.633 0.826
Reach 5 561.45 16 Feb 07 2032 65.541 0.826
Sub 3C - Bypass 99.477 16 Feb 07 2016 9.0131 0.106
basin 3B 32.434 16 Feb 07 2018 3.3430 0.051
nction 4 679.42 16 Feb 07 2030 82.888 1.023
Sub 4A - SWMF #10 133.10 16 Feb 07 2004 7.4320 0.042
SWMF #10 18.798 16 Feb 07 2033 3.6805 0.042

Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
4A - Bypass 10.798 16 Feb 07 2010 0.80145 0.009
basin 9A 22.357 16 Feb 07 2032 4.4819 0.051
Subbasin 4B 0.80979 16 Feb 07 2005 0.046684 0.001
Subbasin 4C 1.1737 16 Feb 07 2005 0.066173 0.001
•
r~
Page: 2

•
FINAL DESIGN OF STORMWA TER
MANAGEMENT FACILITY #1

HIGHLAND CREEK
CTX-06070

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I ° ~~ / /
~ o
~ / ~ ,
~~ ~ ~\
\\ ~ 1 / ~ / /
%~ ~ ~ ~ ` /
\,
~ ~ ~ ~; / /
I~ I /~ ~; I I/.
~ ~ GRAPHIG+ SCALE 1 `~\ ~ ~ ~ '~)
50 / / 0 ~5 50 / I 10~ ~ ~ ~ i / /
l inch = 50 ft.

PEOJECf N0. G`TX-06070
EEK THE JOHN R. McADAMS
FILENAIdE: POND EXHIBITS HIGHLAND CR COMPANY, INC.
~
d 5~~:
~~
~
NORTH CAROLINA
RALEIGH ENGINEERS/PLANNERS/SURVEYORS
~
=50 , RESEARCH TRIANGLE PARK, NC
,~, S'W~~ # 1 ~;i ~'II$Pj P.O. BOX 14005 ZIP 27709-4005
~ DATE, 06-~3-2007 [phone]

HIGHLAND CREEK SWMF #1 J. ALDRIDGE, EI
CTX-06070 5/2/2007
• Stale-Storage Function
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)
275.00 0.00 24433
~ ~ _
__
_.~__~ _
~
___. _ _
____._ _ _
_
276.00 _
1.00 ~ 26924 25679 25679 25679 1.02
278
.00 3.
0
0 31666 29295
- _ .... ___._ _ 58590
_ _...__ __.__ 84269
.__._.._ _~r____ 2.90
_. __._
_
2
....80.00 _ _
_
_
.
5.00 _
366' -
33
. 34150
.
.
..._....
_ 68299
_._..__.___.___.... 152568
_.~_~_.______.__._.. 4.90
~__.._......_._
._~.._~.__
282.00 ___w___J_.___
7.00 __.._._.___._...___.._
_
41827 .
.._ _
._
_v_
39230 78460 231028 7.06
283.00 8.00 44509 43168 43168 274196 8.21
•
300000
250000
~ 200000-
0
rn 150000
R
0
~ 100000
50000
0
0.00
Storage vs. Stage
Ks= 25115
b = 1.1356
C~
2.00 4.00 6:D0 B.OD 10.00
Stage (feet)

•
•
HIGHLAND CREEK
CTX-06070
SWMF #1
_> Stage -Storage Function
Ks= '_5115
6= [.1356
Elevation Storage
(feet( (cf( (acre-feet] 100-YR
275.00 ~ O i 0.000.
~
______
275.20 40380.093
_
275.40 _
Trv~ 0.204
8872
_
_ 275.60 ` ,
061_ 0.323
14
275.8 _
3 ' 0.448
1949
276.00 _
25115 0.577 i
276.20 892 0.709
30 _
276.40 _
_
36802 ~ 0.845
_
276.60 28 ; 0.983
428
276.80 _
48958- ':. 1.124

277.00 _
_
~ 1.267
l80
SS
_
277:20~~ _
_
~~ , ~~1.412 ~
488
~~ 61 -~ _
____ ______
277.40 ~ _
_
67874 ~; 1.558 ~~~
277.60
_. m__1 74332 1.706
.-...__ __._ .1..
277.80 !
0 _80859 _~ 1.856
278.0 87448 ~ 2.008
278:20 ~€ v 94098~'~~2.160 ~~~
278.40 1 805 s 2.3 l4
f 00
278.60~i _
v107565 2.469
278.80 € 114376 ; 2.626
_
279.00 121236 2.783
~
~~~
279.20 ` 128143 2.942
~
~ ~
__
v
279.40 135095 ? 3.101
279.60 3:262
142089 ~__-_____~
279.80 _
I49L25 3'423
280:00 186201 _3.585 ~ ~~_-0-.000 ~_
280.20 163315 ~ 3.74 _~
7 ~0.163
280.40 170467 ~ 3.913 0.327
280:60 ~ 177654 4.078 _
0.493
__._____
28_0.80 ~._____.______.~_.;.__u_._.~
I _184877 4.244
--
0.658
281.00 4.41
192133
~ ~._
_ _
281.20 .
_
199422 i 4.578 0.992
w 28 L40 206743 ; 6 1.160
2S 1.60 a 214095 ~ _4.115 1329
281.80 478 ~ 5.084
221 1.499
_
2.82.00 _
E~228890 j 5:255 L669
___
282.20 236331 ': 5.425
- -
,
0 1.840
282.4

~282.60~ 5.597
243_799
.._._._i_ ..-___._._
1296 ~ 5.769_
28 2.011

2. t 83
282.80 _
25881 942 2356
283.00 266368 ?~6.ti5 2.529
J. ALDRIDGE, EI
8/2/2007
•

HIGHLAND CREEK SWMF #1 J. ALDRIDGE, EI
CTX-06070 6/14/2007
• Extended Detention Wetland Sizing
Source: Stormwater Best Management Practices. NCDENR: Division of Water Quality -
Water Quality Section. April 1999.
Enter the drainage area characteristics =>
Total drainage area to pond = 22.80 acres
Total impervious area to pond = 11.61 acres
Note The wetland must be sized to treat all impervious surface runoff draining into the pond, not just the impervious surface from
on-site development.
Drainage area = 22.80 acres @ 50.9% impervious
Estimate the surface area required at pond normal pool elevation =>
Extended Detention Wetlands are based on a normal pool depth of = 3.0 feet (Per NCDENR Handbook)
From the DWQ BMP Handbook (4/99), the required SA/DA ratio =_>
•
3.0 3.0 4.0
Lower Boundary => 50.0 2.06 1.73
Site % impervious => 50.9 2.09 2.09 1.76
Upper Boundary => 60.0 2.40 2.03

Therefore, SA/DA required = 2.09

Surface area required at normal pool = 20770 ftZ
= 0.48 acres
Surface area provided at normal pool = 24433 ft2
r~

HIGHLAND CREEK -PHASE 2/4 WATER QUALITY VOLUME B. FINCH, PE
CTX-06070 CALCULATIONS 6/28/2007
SWMF #1
> Determination of Water Quality Volume (WQ ~)
WQv = (P)(R v~(A)/!2
where,
WQv =water quality volume (in acre-It)
Rv= 0.05+0.009(I) where I is percent impervious cover
A =area in acres
P =rainfall (in inches)
Input data:
Total area, A = 22.80 acres
Impervious area = 11.61 acres
Percent impervious cover, I = ~;
Rainfall, P = 1.0 inches
Calculated values:
Rv =
WQv = acre-ft
= cf.
__> Drawdown Calculations
Per the NCDENR handbook "Stormwater Best Management Practices" (April 1999), drawdown of the
storm water runoff shall occti~r within 5 clays
•
Input data:
WQv= cf.
Stage /Storage Data:
Ks = 1 ? 0
b=
Zo =
Vol. in 1.0" Rainfall = cu. It
Calculated values:
Depth of WQv in Basin = 1.57 ft
= 18.90 inches
EL = ? %~~. ~ ' ft
•

•
C
HIGHLAND CREEK
CTX-06070
Inverted Siphon Design Sheet
D orifice =
# orifices =
Ks =
b=
Cd siphon =
Normal Pool Elevation =
Volume @ Normal Pool =
Orifice Invert =
WSEL @ 1" Runoff Volume =
SWMF #1
3 inch
1
25115
1.1356
0.60
275.00 feet
0 cf
275.00 feet
276.57 feet
J. ALDRIDGE, EI
6/28/2007
WSEL
(feet) Vol. Stored
(cf) Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
(cf) Incr. Time
(sec)
276.57 42068 0.284
276.44 37945 0.270 0.277 4123 14870
276.30 33874 0.256 0.263 4070 15466
276.16 29862 0.241 0.248 4013 16162
276.03 25913 0.224 0.232 3949 16991
275.89 22034 0.207 0.215 3878 18006
275.75 18236 0.187 0.197 3798 19292
275.62 14530 0.166 0.176 3705 21004
275.48 10935 0.141 0.153 3595 23466
275.34 7478 0.110 0.126 3457 27523
275.21 4207 0.063 0.087 3271 37672
Drawdown Time = 2.44 da s
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 = 0.725 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of 3" orifice = 0.049 sf
Q = 0.2012 cfs
Drawdown Time =Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.42 da s
Conclusion : Use 1 - 3" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 1.0" storm runoff, with a required time of about 2.4 days.
•

Type.... Outlet Input Data
Name.... SWMF #1
Page 1.01
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
• Project Comments:
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 275.00 ft
Increment = .20 ft -~
Max. Elev.= 283.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed.
Structure No. Outfall E1, ft E2, ft
----------------- ---- ------- --------- ---------
Inlet Box RI ---> BA 280.000 283.0.00
Orifice-Circular SI ---> BA 275.000 283.000
Culvert-Circular BA ---> TW 272..000 283.000
TW SETUP, DS Channel
•
• -~
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:43 PM Date: 5/2/2007

Type.... Outlet Input Data
Name.... SWMF #1
Page 1.02
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
• Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = RI
Structure Type = Inlet Box
-----------
------
-------------------
of Openings = 1
Invert Elev. = 280.00 ft
Orifice Area = 25.0000 sq.ft
Orifice Coeff. _ .600
Weir Length = 20.00 ft
Weir Coeff. = 3.0-00
K, Submerged = .000
K, Reberse = 1.000
Kb, Barrel = .000000 (per ft of fu11 flow)
Barrel Length = .00 ft
Mannings n = .0000
Structure ID = SI
Structure Type = Orifice-Circular
# of Openings °.~_ 1
Invert Elev. = 275.00 ft
Diameter = .2500 ft
Orifice Coeff. _ .600
•
•
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:43 PM Date: 5/2/2007

Type.... Outlet Input Data Page 1.03
Name.... SWMF #1
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.P.PW
Title._. Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
• Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = BA
Structure Type = Culvert-Circular
-------------------
-----------------
No. Barrels = 1
Barrel Diameter = 3.0000 ft
Upstream Invert = 272.00 ft
Dnstream Invert = 270.00 ft
Horiz. Length. = 88.00 ft
Barrel Length = 88.02 ft
Barrel Slope = .02273 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000 (forward entrance loss)
Kb = .007228 (per ft of full flow)
Kr = .5000 (reverse entrance loss)
HW Convergence = .001 +/- ft
INLET CONTROL DATA...
Equation form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) = 1.149
T2 ratio (HW/D) = 1.295.
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 Tl Elev = 275.45 ft ---> Flow = 42.85 cfs
At T2 Elev = 275.89 ft ---> Flow = 48.97 cfs

S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:43 PM Date: 5/2/2007

•
Type.... Outlet Input Data
Name.... SWMF #i
Page 1.04
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUT FALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maximum Iterations= 30
Min. TW tolerance = .01 ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .Ol ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
•
C~
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:43 PM
Date: 5/2/2007

•
•
•
Type.... Composite Rating Curve
Name.... SWMF #1
Page 1.14
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
WS E1ev, Total Q
Elev. Q
ft cfs
275.00
_ .00
275.20
~ . 06
275.40 .12
275.60 .I6
275.80 .19
276.00 .22
276.20 .24
276.40 .27
276.60 .29
276.80 .31
277.00 .32
277.20 .34
277.40 .36
277.60 .37
277.80 .39
278.00 .40
278.20 .41
278.40 .43
278.60 .44
278.80 .45
279.00 .47
279.20 .48
2.79.40 .49
279.60 :50
279.80 .51
280.00 .52
280.20 5.90
2.80.40 15.72
280.60 28.44
280.80 4.3.97
281.00 60.98
281.20 79.23
281.40 96.5.4
281.60 97.84
S/N: 621701207003
PondPack Ver. 8.0058
***** COMPOSITE OUTFLOW SUMMARY ****
-------- Converge
TW E1ev Error
ft +/-ft
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfail
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfall
Free Outfali
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 Outfal.l
Notes
-------------------------
Contributing Structures
-(no Q: RI,SI,BA)
SI,BA (no Q: RI)
SI,BA (no Q: RI}
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q; RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,HA (no Q: RI)
SI,BA (na Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
5I,BA (no Q: RI)
SS,BA (no Q: RI)
SI,BA (no Q: RI)
SI,BA (no Q: RI)
RI,SI,BA
RI,SI,BA
RI,SI,BA
RI,SI,BA
RI,SI,BA
RI,SI,BA
RI, BA (no Q: SI)
RI, BA (no Q: SI)
The John R. McAdams Company
Time: 2:43 PM Date: 5/2/2007

•
•
•
Type.... Composite Rating Curve
Name.... SWMF #1
Page 1.15
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16./2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
WS Elev, Total Q
Elev. Q
ft cfs
281.80 99.11
282.00 100.36
282.20 101.61
282.40 102.84
282.60 104.05
282.80 105.25
283.00 106.94
S/N: 621701207003
PondPack Ver. 8.0058
***** COMPOSITE OUTFLOW SUMMARY ****
------- Converge -----
TW Elev Error
ft +/-ft Contr
Free Outfall RI, BA
Free Outfall RIBA
Free Outfall RIBA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RIBA
Free Outfall RI, BA
Notes
Lbuting Structures
(no Q: SI)
(no Q: SI)
(no Q: SI)
(no Q: SI)
(no Q: SI)
(no Q: SI)
(no Q: SI)
The John R. McAdams Company
Time: 2:43 PM Date: 5/2/2007

HMS * Summary of Results for SWMF #1

Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Sxecution Time 14Jun07 1443
Run Name POST [DSSIGN] - Q2
•
Basin Model POST [DESIGN]
Met. Model Q2
Control Specs 1-min dT
Computed Results
Peak Inflow 84.656 (efs)
Peak Outflow 0.51341 (efs)
Total Inflow 2.10 (in)
Total Outflow 0.27 (in)
Date/Time of Peak Inflow 16 Peb 07 2004
Date/Time of Peak Outflow 17 Feb 07 0600
Peak Storage 3.4786(ac-ft)
Peak Elevation 279.87(ft)

HMS * Suttunary of Results for SWMF #1
•
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1448
Run Name POST [DESIGN] - Q10

Basin Model POST (DESIGN]
Met. Model Q10
Control Specs 1-min dT
Computed Results
Peak Inflow 124.94 (efs)
Peak Outflow 20.422 (cfs)
Total Inflow 3.72 (in)
Total Outflow 1.82 (in)
Date/Time of Peak Inflow 16 Feb 07 2004
Date/Time of Peak Outflow 16 Feb 07 2030
Peak Storage 3.9740 (ac-f t)
Peak Elevation 280.47(ft)
•

HMS * Summary of Results for SWMF #1

Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
8xecution Time 14Jun07 1448
Run Name POST [DESIGN] - Q50

Computed Results
Basin Model POST [DESIGN]
Met. Model Q50
Control Specs 1-min dT
Peak Inflow 168.68 (efs) Date/Time of Peak iaflow 16 Feb 07 2004
Peak Outflow 3.755 (c s) Date/Time of Peak Outflow 16 Feb 07 2012
Total Inflow 5.45 (in) Peak Storage 4.6219(ac-f t)
Total Outflow 3.54 (in Peak Elevation 281.25(ft)
~y~l 1~jcD 'Ta C~CA"1E
YE(,pG-t+( D~96tPATOIZ
•

HMS * Summary of Results for SWMF #1
Project CTX-06070 Run Name POST - QTHIRDPMP
• Start of Run 16Feb07 0800 Basin Model POST [DESIGN]
8nd of Run 16Feb07 1400 Met. Model QTHIRDPMP
Execution Time 14Jun07 1449 Control Specs 5-min dT
Computed Results
Peak inflow 160.53 (efs) Date/Time of Peak Inflow 16 Feb 07 1020
Peak Outflow 102.34 (efs) Date/Time of Peak Outflow 16 Peb 07 1035
Total Inflow 8.10 (in) Peak Storage 5.5268(ao-ft)
Total Outflow 6.04 (ia) Peak Elevation 282.32(ft)
•
•

HIGHLAND CREEK
CTX-06070
•
Velocity Dissipa~or - SWMF #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 Manning's roughness number is
constant-over the entire length of the pipe.
Flow QS© (cfs) = 83.76
Slope S (%) = 2.27
Pipe Diameter Do (in) = 36
Manning's `n' = 0.013
Flow Depth (ft) _ 2.09
Outlet Velocity (fps) = 15.91
NRCD Land Quality Section
1VYDOT Dissipator Design Resielts
•
Pipe Diameter (ft) = 3.00
Outlet Velocity (fps) = 15.91
Apron Length (ft) _ 30.00
d50 Stone Thickness
(inches) Class (inches)
--- 4 A 9
8 B 22
10 1 22
-~ 14 2 27 t-
Width = La + Do
Width = 30 + 3
Width (ft) = 33
Use NCDOT Class `2' Rip Rap
d50 = 14"
30'L x 33'`V x 27"Thick
J. ALDRIDGE, EI
5/3/2007
•

HIGHLAND CREEK SWMF #1 J. ALDRIDGE, EI
CTX-06070 5/3/2007
Square RiserBarrel Anti-Flotation Calculation Sheet
• Input Data __>
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 = 8.00 feet
Concrete unit weight = 142.0 PCF
OD of barrel exiting manhole = 4$:50 inches
Size of drain pipe (if present) _ 8.0 inches
Trash Rack water displacement = 61.74 CF
Concrete Present in Riser Struch~re =>
Note: tit. Products ii,ts unit wt. of
nian[urte eo~F~rete aE [-12 PCF`_
Total amount of concrete:
Base of Riser = 24.000 CF
Riser Walls = 88.000 CF
Adjust for openings:
Opening for barrel = $.646 CF
Opening for drain pipe = 0,17$ CF
• Total Concrete present, adjusted for openings = 106.180 CF
Weight of concrete present = 15078 !bs
Amount of water displaced by Riser Structure =_>
Displacement by concrete = 106.180 CF
Displacement by open air in riser = 200.000. CF
Displacement by trash rack = 61.740 CF
Total water displaced by riser/barrel structure = 367.920 CF
Weight of water displaced = 22958 lbs
Calculate amount of concrete to be added to riser =_>
Safety factor t0 use = 1.1$ !recommend (. I ~ or hi~;tcr't
Must add = 11324 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 = 163.606 CF of concrete
Standard based described above = 24.000 CF of concrete
• Therefore, base design must have = 187.606 CF of concrete

HIGHLAND CREEK SWMF #1 J. ALDRIDGE, EI
CTX-06070 5/3/2007
• Calculate size of base for riser assembly =_>
Length = 9.000 feet
Width = 9.000 feet
Thickness = 28.0 inches
Concrete Present = 189.000 CF OK
Check validity of base as designed =_>
Total Water Displaced = 532.920 CF
Total Concrete Present = 271.180 CF
Total Water Displaced = 33254 lbs
'Total Concrete Present = 38508 lbs
Actual safety factor = 1.16 OK
Results of design =>
•
Base length = 9.00 feet
Base width = 9.00 feet
Base Thickness = 28.00 inches.
CY of concrete total in base= 7.00 CY
Concrete unit weight in added base >= 142 PCF
•

ABE VOLUME CALCULATORS, PYRAMIDLONG
Page 1 of 1
('ALt:I?L:~11`L ~'(~LLl-II+; C)F P~'ItAI~I:ID «ITII I~Ini~`II3tiAI1 i~`IDTHS A:~II) LEl\GTI-IS
• i~:ntez- all l;.ncftir~n ~s-ait~e5 in the t'o~°ttr belo•+i stntl Press the "(:Ai:t`LLA`I`E" buttv~i.
•
f.~~:~ t~~: iJ~~i€ t'c>>,tt ~r5ior;.I.'ti7~
C,
http://abe.msstate.edu/~fto/tools/vol/pyramidlong.html 5/3/2007

•

HIGHLAND CREEK SWMF #1 Level Spreader Outlet Velocity Calculations
CTX-06070
1" storm peak flow rate = 0.12 cfs
Determine depth of the flow over level spreader weir:
Q = CWLH3iz
CW
L=
Q-
H=
HAT WEIR
Determine velocity offlow over le
Q
V
H = (Q/CWL)z~3
= 3.0
= 15.75 ft
= 0.12 cfs
= 0.019 ft
= 2/3 H = 0.012 ft
~vel spreader weir:
VA
= Q/A
Q/(L*HAT WEIR)
Q = 0.12 cfs
L = 15.75 ft
HAT WEIR - 0.012 ft
V = 0.61 ft/sec
Therefore, the approximate velocity over the level spreader weir is 0.65 fdsec.
J. ALDRIDGE, EI
6/14/2007
•

HMS * Summary of Results for SF]MF #1
•
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1615
Run Name POST [DESIGN] - Q1"
•
Basin Model POST [DESIGN]
Met. Model 1" STORM
Control Specs 1-min dT
Computed Results
Peak Inflow 5.7124 (efs)
Peak Outflow 0.12405 (efs)
Total inflow 0.17 (in)
Total Outflow 0.06 (in)
Date/Time of Peak inflow 16 Feb 07 1958
Date/Time of Peak Outflow 17 Feb 07 0628
Peak Storage 0.21605(ac-f t)
Peak Elevation 275.42(ft)
~~

•
FINAL DESIGN OF STO.RMWATER
MANAGEMENT FACILITY #2
r~

HIGHLAND CREEK
CTX-06070

~ / , ~,.
,~
I_ ~ ~ j i // ~~ ~`~ 1, "/~, ~ X~ }
/
~. ~
r ( ~~ ~ ~ ~ ~
/ r ,/~~/ _~\ /
r r ,- ~ ~ ~ r
,~~~r %r~~~~~~ ~~
~ ~ ~~,_\~
~ ~,
l l ~l 11 ~ ~~~~;~s ~; ii ~~ \ i
\ \ ~~ ~ X825- _,, - ~ ~~ ~ ~ ~ ~,
~ ~ ~ ~ ~ ~ ~ 282 ~ ~. ~ ~ ~ ~ , ~
1 ~ ~~ ~ ~ ~ ~ 84 ~ ~` ° ~ ~ 1
l \ \ \~\ \\ ? 28 4 285 \ \ ~I ~ ~ \
\ \\\ 880 \ ' / ~'
\ ~~ ~ ~ ~ .~
\\ ~ ~ ~'
~ , ~~ ~
\ ~
~ ~ I ~ ~'+
\ G AP~IC SCALE I \ ~ \ ~ -
~ l ~.,-
1 50 \ \ 0 \ ~ ~50 10~ \ \ _ /
1 inch = 50 ft.

PROJECT N0. CTX-06070
THE JOHN R. McADAMS
FILENAME: HIGHLAND CREEK COMPANY
INC
POND EXHIBITS ,
.
d scALE:

n
,
NORTH CAROLINA
RALEIGH
ENGINEERS/PLANNERS/SURVEYORS
~
-50 , RESEARCH TRIANGLE PARK, NC
DATE: S~l~u' #2 E[aIIIBiT P.O. BOX 14005 ZIP 27709-4005
~
06-13-2007 [phone]

HIGHLAND CREEK SWMF #2 J. ALDRIDGE, EI
CTX-06070 5/2/2007
• Stage-Storage Function
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)
278.00 0.00 14506 _
__
-.__. _
__....._
._,_...._
_._ 280.00 2.00 17731
~ 161 l9
~ 32237 32237 2.02
_
282.00 ~ ~ 4.00'
._ 21 l 83
_..___.~A_ (9457
-~.----_ 38914
_.-__~..~ _------. 7115 l
---- _ ._ _._.___ _.__ 3.93
__ _._. _..._......._.__ _ ...
_--_ ______._.
284.00 _______
6.00 24860 23022 46043 117194 5.99
285.00 7.00 26783 25822 25822 143016 7.08
•
Storage vs. Stage
lsoooo _____....-.._._.._____._....~___..._.___.________._...._____...._......_,
140000
y = 14034x1~t859
120000
Z
= 0.9995
R
cLLi 100000
°1rn 80000
[
60000 ~

40000

20000 i

0
0.00 2.00 4.00 6.00 8.00
Stage (feet)
Ks = 14034
b = 1.1859
•

CJ
•
HIGHLAND CREEK
CTX-06070
SWMF #2
_> Stage -Storage Ftmctiore
Ks = 14{134
b= 1.1859
Zo = ?78.00
Eleva~iod ~ Storage ~~~
[feet) [cf[ [acre-feet [ 100-YR

278.00 .. r
0 , ~....., Y... ~. ~,.,
i 0.000 ».
__ _ ____T__„_
278.20 2081 0.048
"`~
~~~`"~~.__
"~
278.40 _
4734 ~
.- .
~
? --_.0.109 __E_.__.....__..____
.
_
278.60 7658 ~ 0.176
~ r
278.80 10771 _ 0.247
'
279.00 14034 ~ 0.322_
~
-~
~-.~
"" ..___._..
279.20 17421 0.400
3 ~
__~ --- ~-__..___
279.40 20916 _0.480
T 4
-~_...__,__._._
-~
279:60 24505 0.563
: ~
~
.~~ ~ ~~
~~
279.80 _
28178 ~~ 0.647 ~
~
280.00 31928_ = 0.733
~.~~-
~~~_~
-~~280.20 35749 0.821
~
~
~ ~-~~~~~~-~_.._._.
280.40 ~ 39635_ 0.910
__`
~
~ ~
~ .._.__ ~..__.__
280.60 43581 1.000 __ _________________.
280.80 ___._.__._._
47585 _>__...._____r__
L092
~~ ~~ ~~~~~~~~
28 L00 51642 L 186
281.20 55749 1.280
281.40 _ 5990_5 ~_ 1.375
~~
~
~ .
_
28!.60 64106 1.472
_'
~.
~~~ __ ~_ __.~.
~~~
281.80
__
282.00 68_351
72638~ 1.569
_Y
_ . _
~~ L668 _-t_---_ _...._..._...__.
`
282.20 76965 1.767
~
~~~.~
~ ~~_..__._.
2_8_2.40_
282.60 81330
85733 1.867
1968
~ 0.000 W__.
~~
282.80 90.171 2.070
` _
0.102
_
_
283
00 94643 ~. 217
3 0.205
_
. _ ~ ~~~

283.20 _
~ 99149
_ 2.276_ _
0.308_ __
'
283.40 ~103688 2 380 0.412
~ _ ~
283.60 1 108257 2 485 0.517
283.80 1.12858 ~ 2 591 1 0 623
284.00 1 17487
~~ 2 697 0.729__
-
-
284.20 ~
122146 ~ 2.804 0.836
284.40 126832
___ 2.912
_.w __._ _._~ ; 0.944
__._,. __.___-__
_ _. .. ..
284.60 [ l3 t 546 i 3.020
~ ~ L052 _
_
_ 2_84.8_O~
285:0 t 136287
0 1053 3 12_9
,
~ 3 238 L161 _
1.270
J. ALDRIDGE, EI
5/2/2007
•

HIGHLAND CREEK SWMF #Z J. ALDRIDGE, EI
CTX-06070 5/2/2007
Extended Detention Wetland Sizing
• Source: Stormwater Best Management Practices. NCDENR:.Division of Water Quality -
Water Quality Section. April 1999.
Enter the drainage area characteristics =_>
Total drainage area to pond = 12.18 acres
Total impervious area to pond = 6.90 acres
Drainage area = 12.18 acres @ 56.7% impervious
Estimate tl:e surfirce area required at pond normal pool elevation =>
Extended Detention Wetlands are based on a normal pool depth of = 3.0 feet (Per NCDENR Handbook).
From the DWQ BMP Handbook (4/99), the required SA/DA ratio =_>
•
Note The wetland m~crt be sized to trent at/ impen~ious surface r~rnojf draining into the pond, not just the rmpervioirs surfncefrom
on-site development.
3.0 3.0 4.0
Lower Boundary => 50.0 2.06 1.73
Site % impervious => 56.7 2.29 2.29 1.93
Upper Boundary => 60.0 2.40 2.03
Therefore, SA/DA required = 2.29
Surface area required at normal pool = 12129 ftz
= 0.28 acres
Surface area provided at normal pool = 14506 ft2
•

•
HIGHLAND CREEK -PHASE 2/4
CTX-06070
WATER QUALITY VOLUME
CALCULATIONS
SWMF #2
=a Determination of Water Quality Volume (WQ ~)

where,
WQv =water quality volume (in acre-ft)
Rv= 0.05+0.009(I) where I is percent impervious cover
A =area in acres
P =rainfall (in inches)
Input data:
Total area, A = 12.18 acres
Impervious area = 6.90 acres
Percent impervious cover, I = X6.7
Rainfall, P = 1.0 inches
Calculated values:
Rv= ''._
WQv = ). ; ? acre-ft
_ _ 'S_~ cf.
r~
=> Drawdown Calculations
Per the NCDENR handbook "Stormwater Best Management Practices" (April 1999), drawdown of the
stormwater runoff shall occur within S days
Input data:
WQv= ''- cf.
Stage /Storage Data:
Ks =
b=
Vol. in 1.0" Rainfall = _- cu. ft
Calculated values:
Depth of WQv in Basin = 1.61 ft
= 19.36 inches
EL = ?79.61 ft
B. FINCH, PE
6/27/2007
•

HIGHLAND CREEK
CTX-06070
Inverted Siphon Design Sheet
•

D orifice =
# orifices =
Ks =
b=
Cd siphon =
Normal Pool Elevation =
Volume @ Normal Pool =
Orifice Invert =
WSEL @ 1" Runoff Volume =
SWMF #2
2 inch
1
14034
1.1859
0.60
278.00 feet
0 cf
278.00 feet
279.61 feet
WSEL
(feet) Vol. Stored
(cf) Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
(cf) Incr. Time
(sec)
279.61 24753 0.130
279.48 22259 0.124 0.127 2494 19676
279.34 19808 0.117 0.121 2451 20322
279.20 17405 0.111 0.114 2404 21067
279.06 15052 0.104 0.107 2353 21941
278.92 12755 0.096 0.100 2296 22991
278.78 10522 0.088 0.092 2233 24287
278.65 8361 0.079 0.083 2161 25957
278.51 6285 0.068 0.074 2076 28241
278.37 4313 0.056 0.062 1972 31695
278.23 2475 0.040 0.048 1837 38077
Drawdown Time = 2.94 da s
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 = 0.765 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of 2" orifice = 0.022 sf
Q = 0.0919 cfs
Drawdown Time =Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 3.12 da s
,,Conclusion : Use 1 - 2" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 1.0" storm runoff, with a required time of about 3.0 days.
7. ALDRIDGE, EI
6/28/2007
•

•
Type.... Outlet Input Data Page 1.01
Name.... SWMF #2
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
REQUESTED POND WS ELEVATIONS:
.Min. Elev.= 278.00 ft
'-Increment = .20 ft
Max. Elev.= 285.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed
•
Structure
Inlet Box
Orifice-Circular.
Culvert-Circular
TW SETUP, DS Channel
No. Outfall E1, ft
- E2, ft
---------
----
RI -------
---> BA --------
282.600 285.000
SI ---> BA 278.000 285.000
BA ---> TW 275.000 285..000
s
•
S/N: 621701207003
PondPack Ver. 8.0058
The John R. McAdams Company
Time: 2:46 PM Date: 5/2/2007

•
Type.... Outlet Input Data
Name.... SWMF #2
Page 1.02
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = RI
Structure Type = Inlet Box
# of Openings = 1
Invert Elev. = 282.60 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
Structure ID = SI
Structure Type = Orifice-Circular
# of Openings = 1
Invert Elev. _ 278.00 ft
Diameter = .1667 ft
Orifice Coeff. _ .600

•
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:46 PM Date: 5/2/2007

•
•
•
Type.... Outlet Input Data Page 1.03
Name.... SWMF #2
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2!16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = BA
Structure Type = Culvert-Circular
------------------------------------
No. Barrels = 1
Barrel Diameter = 2.5000 ft
Upstream Invert = 275.00 ft
Dnstream Invert = 274.00 ft
Horiz. Length = 68.00 ft
Barrel Length = 68.01 ft
Barrel Slope = .01471 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000 (forward entrance loss)
Kb = .009217 (per ft of full flow)
Kr = .5000 (reverse entrance loss)
HW Convergence = .DO1 +/- 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) = 1.153
T2 ratio (HW/D) = 1.299
Slope Factor = -.500
Use unsubmerged inlet control Form 1 equ. below T1 elev.
Use submerged inlet control Form 1 equ. above T2 elev.
s-~° In transition zone between unsubmerged and submerged inlet control,
interpolate between flows at T1 & T2...
At T1 Elev = 277.88 ft ---> Fiow = 27.16 cfs
At T2 Elev = 278.25 ft ---> Flow = 31.05 cfs
S/N. 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:46 PM Date: 5/2/2007

•

•
Type.... Outlet Input Data
Name.... SWMF #2
Paqe 1.04
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
"i;
Structure ID = TW
Structure Type = TW SETUP, DS Channel
FREE OUT FALL CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .O1 ft
Max. TW tolerance = .O1 ft
Min. HW tolerance = .O1 ft
Max. HW tolerance = .Ol ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
S/N: 621"7012U70C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:46 PM Date: 5/2/2007

•
•
•
Type.... Composite Rating Curve
Name.... SWMF #2
Page 1.13
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2 /16/2007
Project Enginee r: J. ALDRIDGE, EI
Project Titl e: HIGHLAND CREEK
Project Comment s:
***** COM POSITE OUTFLOW SUMMARY ****
WS Elev, Total Q Not es
-------- -------- ------ -- Converge ------- ---- --- -----------
Elev. Q TW El ev Error
ft cfs ft +/-ft
----- Contrib
-------- utin
---- g Structures
--------------
--------
278.00 -------
.00 ------
Free --
Outfall (no Q: RI, SI, BA)
278.20 .04 Free Outfall SI,BA (no Q: RI}
278.40 .06 Free Outfall SI,BA (no Q: RI)
278.60 .OB Free Outfall SI,BA (no Q. RI)
278.80 .09 Free Outfall SI,BA (no Q: RI)
279.00 .10 Free Outfall SI,BA (no Q: RI)
279.20 .11 Free Outfall SI,BA (no Q: RI)
279.40 .12 Free Outfall SZ,BA (no Q: RI)
279.60 .13 Free Outfall SI,BA (no Q: RI)
279.80 .14 Free Outfall SI,BA (no Q: RI)
280.00 .15 Free Outfall SI,BA (no Q:. RI)
280.20 .15 Free Outfall SI,BA (no Q: RI)
280.40 .16 Free OutfaTl SI,BA (no Q: RI)
280.60 .17 Free. Outfall SI,BA (no Q: RI)
280.80 .17 Free Outfali SI,BA. (no Q: RI)
281.00 .18 Free Oatfall SI,BA (no Q: RI)
281.20 .19 Free Outfall SI,BA (no Q: RI)
281.40 .19 Free Outfall SI,BA (no Q: RI)
281.60 .20 Free Outfall SI,BA (no Q: RI)
281.80 .20 Free Outfall SI,BA (no Q: RT)
282.00 .21 Free Outfdll SI,BA (no Q: RI)
262.20 .21 Free Outfall SI,BA (no Q: RI)
282.40 .22 Free Outfall SI,BA (no Q: RI)
282.60 .22 Free Outfail SI,BA (no Q: RI)
282.80 5.59 Free Outfall RI,SI,BA
283.00 15.41 Free Outfall RI,SI,BA
283.20 28.12 Free Outfall RI,SI,BA
263.40 43.13 Free Outfall RI.,SI,BA
283.60 60.10 Free Outfall RI, BA (no Q: SI)
283.80 65.76 Free Outfall RI, BA (no Q: SI)
284.00 66.67 Free Outfall RIBA (no Qc SI)
284.20 67.58 Free Outfall RI, BA (no Q: SI)
289.40 68.47 Free Outfall RI, BA (no Q: SI)
284.60 69.34 Free Outfall RIBA (no Q: SI)
S/N. 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:46 PM Date: 5/2/2007

•
Type.... Composite Rating Curve
Name.... SWMF #2
Page 1.14
Eile.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK.
Project Comments:
***** COMPOSITE OUTFLOW SUMMARY ****
•

WS E1ev, Total Q Notes
-------- -------- -------- Converge --` ---------------------
Elev. Q TW Elev Error
ft cfs ft +/-ft Contributing Structures
284.80 70.21 Free Outfall RI, BA (no Q: SI)
285.00 71.07 Free Outfall RIBA (no Q: SI)
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:46 PM Date: 5/2/2007

HMS * Summary of Results for SWMF #2
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1443
Run Name POST [DESIGN] - Q2
Basin Model POST [DESIGN]
Met. Model Q2
Control Specs 1-min dT
Computed Results
Peak inflow 48.634 (efs)
Peak Outflow 0.52552 (cfs)
Total Inflow 2.27 (in)
Total Outflow 0.32 (in)
Date/Time of Peak Inflow 16 Feb 07 2004
Date/Time of Peak Outflow 17 Feb 07 0250
Peak Storage 1.9738(ac-f t)
Peak Elevation 282.61(ft)
•
•

HMS * Summary of Results for SWMF #2
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1448
Run Name POST [DESIGN] - Q10
Basin Model POST [DESIGN]
Met. Model Q10
Control Specs 1-min dT
Computed Results
Peak Inflow 69.746 (efs)
Peak Outflow 15.176 (cfs)
Total Inflow 3.92 (in)
Total Outflow 1.97 (in)
Date/Time of Peak Inflow 16 Feb 07 2004
Date/Time of Peak Outflow 16 Feb 07 2022
Peak Storage 2.1705(ac-ft)
Peak Elevation 283.00(ft)
•
.,
.~

HMS * Summary of Results for SWMF #2
•
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1448
Run Name POST [DESIGN] - Q50
Basin Model POST [DESIGN]
Met. Model Q50
Control Specs 1-min dT
•
Computed Results
Peak Inflow 92.802 (efs) Date/Time of Peak inflow 16 Feb 07 2004
Peak Outflow 58.115 (efs) Date/Time of Peak Outflow 16 Feb 07 2010
Total inflow 5.67 (in Peak Storage 2.4725(ac-f t)
Total Outflow 3.72 (i ) Peak Elevation 283.58(ft)
~~ uSEa To G1Rtt+~ taA~TaE
1r6t.,oCaj"f I>tSS~PR~'~
•

HMS * Summary of Results for SWMF #2
Project CTX-06070
• Start of Run 16Feb07 0800
Snd of Run 16Feb07 1400
Execution Time 14Jun07 1449
Run Name POST - QTHIRDPMP
Hasin Model POST [DESIGN]
Met. Model QTHIRDPMP
Control Specs 5-min dT
Computed Results
Peak Inflow 88.156 (cfs) Date/Time of Peak inflow 16 Feb 07 1015
Peak Outflow 69.285 (efs) Date/Time of Peak Outflow 16 Feb 07 1030
Total Inflow 8.35 (in) Peak Storage 2.7481(ac-f t)
Total Outflow 6.28 (in) Peak 8levation 284.10(ft)
•
•

•
HIGHLAND CREEK
CTX-06070
Velocity Dissipator - SWMF #2
NRCD Land Quality Section
Pipe Design
"` •' Entering the folio iw ng values will provide you with
the expected outlet velocity and depth of flow in a
pipe, assuming the Manning's roughness number is
constant over the entire length of the pipe.
Flow QSO (cfs) = 58.12
Slope S (%) =.1.47
Pipe Diameter Do (in) = 30
Manning's `n' = 0.013
Flow Depth (ft) = 2.50
Outlet Velocity (fps) = 1:1.84
NRCD Land Quality Section
NYDOT Dissipator Design Results
•
Pipe Diameter (ft) = 2.50
Outlet Velocity (fps) _ 11.84
Apron Length (ft) = 20.00
d50 Stone Thickness
(inches) Class (inches)
4 A 9
8 B 22
-> 10 1 22 F-
14 2 27
Width = La + Do
Width = 20 + 2.5
Width (ft) = 22.5
Use NCDOT Class `1' Rip Rap
d50 =10"
20'L x 23'W x 22"Thick
J. ALDRIDGE, EI
5/3/2007
•

HIGHLAND CREEK SWMF #2 J. ALDRIDGE, EI
CTX-06070 5/3/2007
Spuare RiserBarrel Anti-Flotation- Calculation Sheet
• Input Data =>
Inside length ofriser
Inside width of riser =
Wall thickness of riser =
Base thickness of riser =
Base length ofriser
.Base width of riser =
Inside height of Riser =
Concrete unit weight =
_'_t~f barrel exciting manhole =
' ...S:iae of drain pipe (if present) _
Trash Rack. water displacement =
Concrete Present in Riser Struehire =>
Total amount of concrete:
Adjust for openings:.
5.00 feet
5.00 feet ~.
6.00 inches
8.00 inches
6.00 feet
6.00 feet
7.60 feet
142.0 PCF Vote: tiC' Pnxiucts lists unit at. nt
38.50. inches manhole eut}~rete at I ~2 PCF.
"8.0 inches
61.74 CF
Base of Riser = 24.000 CF
Riser Walls = 83.600 CF
Opening for barrel = 4.042 CF
Opening for-drain pipe = 0.175 CF
• Total Concrete present, .adjusted for openings = 103.383 CF
Weight of concrete present = 14680 !bs
Amount of water displaced by Riser Structure =>
Displacement by concrete = 103.383 CF
Displacement by open air in riser = 190.000 CF
Displacement by trash rack = 61.740 CF
Total water displaced by riser/barrel structure = 355.123 CF
Weight of water displaced = 22160 Ibs
Calculate amount of concrete to be added to riser =>
~:: Safety factor t0 use = 1.1$ (recommend [.1 ~ or highet'1
~- `' Must add = 10$03 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 = 156.077 CF of concrete
Standard based described above = 24.000 CF of concrete
• Therefore, base design must have = 180.077 CF of concrete

HIGHLAND CREEK SWMF #2 J. ALDRIDGE, EI
CTX-06070 5/3/2007
• Calculate size of base for riser assembly =_>
Length = 9.000 feet
" Width = 9.000 feet
Thickness = 27.0 inches
Concrete Present = 182.250 CF nIC
Check validity of base as designed =_>
Total Water Displaced = 513.373 CF
Total Concrete Present = 261.633 CF
Total Water Displaced = 32034 Ibs
Total Concrete Present = 37152 lbs
Actual safety factor = 1.1.6 OK
Results of design =>
•
Base length = 9.00 feet-
Base width = 9.00 feet
Base Thickness = 27.00 inches
CY of concrete total in base = 6.75 CY
Concrete unit weight in added base >= 142 PCF
•

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Yage 1 of 1
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• i!:nt~r all 1;iai~~r~n -~alcces in the for•c~c~t t~etati~ scud press ttce "C'AI.:C,'l.`l.,A`7'E`• butl:on.
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~.
;r ?;>
.,,. rt ,y
.~~.~~ ~ ,F;~~~.:..

8.4 8.4 2.1 2.1 ~ 61.74
l~l~e a~~~ti~~~;~ t~~~:~s: ~~c~~~ c~ti, ~;:c~~?4 i<>r otii~r list 61.74

C7
http://abe.msstate. edu/~fto/tools/vol/pyramidlong.html
5/3/2007

HIGHLAND CREEK SWMF #2 Level Spreader Outlet Velocity Calculations
CTX-06070
• 1" storm peak flow rate = 0.07 cfs
Determine depth of the flow over level spreader weir:
Q = C~yL113/2
H = (Q/CWL)2/s
CW = 3.0
L = 15.75 ft
Q = 0.07 cfs
H = 0.013 ft
HAT wElx = 2/3 H = 0.009 ft
Determine velocity of flow over level spreader weir.•
Q = VA
V = Q/A
Q = 0.07 cfs
• L = 15.75 ft
HAT WEIR - 0.009 ft
V = 0.51 ft/sec
Therefore, the approximate velocity over the level spreader weir is 0.55 ft/sec.
J. ALDRIDGE, EI
6/14/2007
•

HMS * Summary of Results for SWMF #2
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1615
Run Name POST (DESIGN] - Q1"
Basin Model POST [DESIGN]
Met. Model 1" STORM
Control Specs 1-min dT
Computed Results
Peak Inflow 4.2147 (efs)
Peak Outflow 0.074288 (efs)
Total Inflow 0.22 (in)
Total Outflow 0.07 (in)
Date/Time of Peak inflow 16 Feb 07 1958
Date/Time of Peak Outflow 17 Feb 07 0723
Peak Storage 0.15687 (ac-f t)
Peak Elevation 278.54(ft)
•
•

•
FINAL DESIGN OF STORMWATER
MANAGEMENT FACILITY #7
•

HIGHLAND CREEK
CTX-06070

1 I TOP OF DAM \ \ I \ 11 \
~ / / ~ / I 12' WIDE MIN.) 272. \ ~ ; \ \ ~
1\~ 1 I ~, ~ ~ I <,~ 11 I ~ ~ ,- ____ _ ~
\/ ~
~~ \ 1 I I ~r~ II ~INa I ~~~ // \ ~ \
~/ / _ ~
\I I
\ I I ~' I I ~ 11 I ( I ~` I~`J/ I ~1 /N y°^N \ -- ~ \ \
I I I 7/ I I ~I II \ 1 II` I I` ~ ~ / ~ ~ NNty ~° / \ _~ ~` ~ I I~
~~ ~ ~ N ~ ~ \
~ I ~ ~~ ~ 1 / it I I I i \ `~\ \~ \ \ i - I
~ ,\ \ \
II ~ ~
I~
t ~ ~ ~ N/ 265' ~~
-_ _ ~
/ , / ~ i / / / / / /I I/ / 60/ G~RAPHIC~ SCAIfE
~ ~ ~ ~ a~ / / l I ~ ~ ~ 60 , 20
1 inch = 60 ft. J

PR07ECT N0. CTX-06070
CREEK THE JOHN R. McADAMS
FILENA>.aE: POND EXHIBITS HIGHLAND COMPANY, INC.
~
d 5~~:
.~
~
NORTH CAROLINA
RALEIGH ENGINffiRS/PLANNERS/SURVEYORS
,
=60 , RESEARCH TRLINGLE PARK, NC
,~ 5`w~ #'] ~BiT P.O. BOX 14005 ZIP 27709-4005
`~' °A~` 06-13-2007 [phone]

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 5/2/2007
• Stake-Storage Function
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)
266.50 0.00 29498 _ _ _
_
_
268.OU _
~ 1.50 33482 31490 47235 47235 L5l
270.00 3.50 38992 36237 72474 119709 3.46
272.00 5.50 44729 41861 83721 203430 5.55
•
Ks = 29839
b = 1.1205
•

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 6/28/2007
-~ Stage -Storage Function
• Ks = 29839
b = L 1205
Zo = 266.50
•
Elevation ~
(feet] j
(cfJ Storage
[acre-feet]
100-YR
266.50 i 0 0.000 _ ~__ _~
.__
266.60 ' _
2261 ~ 0.052
____
266.80 7743 ' 0.178 g
267.00 _T 13724 _
0.315 _
_
267.20 t 20009 i 0.459 _
j
267.40 26516 0.609 _ ~~
267.60 33202 0.762
267.80 ~ 40037 ~ 0.919 j
268.00 ! 47000 j 1.079 ? 0.000
268.20 54076 ~ 1.241 ~- 0.162
268.40 61253 1.406 0.327
268.60 68522 j 1.573 0.494
268.80 75875 ~ 1.742 j 0.66_3
269.00 83306 _ 1.912 _ ' 0.833
269.20
~ 90809 2.085 _ 1.0_06 __
~~
__
_
269.40
; 98379 2.258 1.180 _~
_
269.60 t 106012 2.434 ~ 1.355
_s .~~
_
i~
269.80 l 13705 _
; 2.67 0
J l .531 __
~~_
_
270.00 ~ 121454 2.788 _ 1.709 __
.._
_ 270.20 _J~- 129257 2.967_
-- l .888
_
_
270.40
- 137111_ _3.148
_ 2.069
_
270.60_ _-
__ 270.80 ~
271.00 ~
271.20-
271.40 `,
271.60
271.80 ` 145014
152963
160957
168993
177072
185190_
193346 ~_ 3.329
l 3.512
___3.695
3.880
4.065
' 4.251
4.439_.
` 2.250
'- 2.433
2.616_
2.801
! 2.986
3.172
_3`360_ _
272.00 201540 _
` 4.627 3.548
•

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 6/14/2007
Extended Detention Wetland Sizing
• Source: Stormwater Best Management Practices . NCDENR: Division of Water Quality -
Water Quality Section. April 1999.
Enter the drainage area characteristics =>
Total drainage area to pond = 31.67 acres
Total impervious area to pond = 12.46 acres
Note The wetland must 6e sized to treat all impervious surface runoff draining into the pond, not just the impervious surface from
on-site development.
Drainage area = 31.67 acres @ 39.3% impervious
Estimate the surface area required at pond normal pool elevation =_>
Extended Detention Wetlands are based on a normal pool depth of = 3.0 feet (Per NCDENR Handbook)
From the DWQ BMP Handbook (4/99), the required SA/DA ratio =_>
3.0 3.0 4.0
Lower Boundary => 30.0 1.34 1.08
Site % impervious => 39.3 1.70 I.70 1.41
Upper Boundary => 40.0 1.73 1..43

• SA/DA re
uired =
re
Th
f 1
70
q
ere
o
, .

Surface area required at normal pool = 23512 ft2
= 0.54 acres
Surface area provided at normal pool = 29498 ft2

HIGHLAND CREEK -PHASE 2/4 WATER QUALITY VOLUME B. FINCH, PE
CTX-06070 CALCULATIONS 6/27/2007
SWMF #7
• => Determination of Writer Quality Volume (WQ ~)
WQv = (P) (R v) (A)/12
where,
WQv =water quality volume (in acre-ft)
Rv= 0.05+0.009(I) where I is percent impervious cover
A =area in acres
P =rainfall (in inches)
Input data:
Total area, A = 31.67 acres
Impervious area = 12.46 acres
Percent impervious cover, I = 39.3
Rainfall, P = 1.0 inches
Calculated values:
R - !i.-~U
v-
WQv = ~ '~~ 7 acre-ft
=> Drhwdown Calculations
Per the NCDENR handbook "Stormwater Best Management Practices" (Apri11999), drawdown of the
stormwater runoff shall occur within S days
•
Input data:
WQ~ _ --: , cf.
Stage /Storage Data:
Ks = _ _
b= ! ':
Zo = _- .
Vol. in 1.0" Rainfall = -'~ ~ ~-~.; ~~ cu. ft
Calculated values:
Depth of WQv in Basin = 1.48 ft
= 17.81 inches
EL = 267.98 ft
•

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 6/28/2007
•
Inverted Siphon Design Sheet
D orifice =
# orifices =
Ks =
b=
3 inch
1
29839
1.1205
0.60
266.50 feet
0 cf
266.50 feet
267.98 feet
Cd siphon =
Normal Pool Elevation =
Volume @ Normal Pool =
Orifice Invert =
WSEL @ 1" Runoff Volume =

WSEL
(feet Vol. Stored
(cf) Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
(cf) Incr. Time
(sec)
267.98 46455 0.275
267.86 41941 0.262 0.268 4514 16816
267.73 37479 0.248 0.255 4462 17524
267.60 33073 0.233 0.240 4406 18353
267.47 28730 0.217 0.225 4343 19344
267.34 24456 0.199 0.208 4274 20563
267.21 20261 0.180 0.190 4195 22116
267.08 16159 0.159 0.170 4103 24199
266.95 12166 0.134 0.147 3993 27232
266.82 8312 0.104 0.119 3855 32334
266.69 4645 0.056 0.080 3666 45934
Drawdown Time = 2.83 da s
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 = 0.680 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of 3" orifice = 0.049 sf
Q = 0.1949 cfs
Drawdown Time =Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.76 days
Conclusion : Use 1 - 3" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 1.0" storm runoff, with a required time of about 2.8 days.
C7

•
Type.... Outlet Input Data Page 1.01
Name.... SWMF #7
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 266.50 ft
Increment = .20 ft
Max. Elev.= 272.00 ft
Spot Elevations, ft
266.50
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream)
<--- Reverse Flow Only (DnStream to Upstream)
<---> Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
Inlet Box RI ---> BA 268.000 272.000
Orifice-Circular SI ---> BA 266.500 272.000
Culvert-Circular BA ---> TW 261.000 272.000
TW SETUP, DS Channel

•
S/N: 621701207003 The John R> McAdams Company
PondPack Ver. 8.0058 Time: 5:19 PM Date: 6/28/2007

Type.... Outlet Input Data
Name.... SWMF #7
Page 1.02
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = RI
Structure Type = Inlet Box
------------------------------
# of Openings = 1 ------
Invert Elev. = 268.00 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
Structure ID = SI
Structure Type = Orifice-Circular
# of Openings = 1
Invert Elev. = 266.50 ft
Diameter = .2500 ft
Orifice Coeff. _ .600
•
•
S/N: 621701207003 The John R> McAdams Company
PondPack Ver. 8.0058 Time: 5:19 PM Date: 6/28/2007

•
Type.... Outlet Input Data
Name.... SWMF #7
Page 1.03
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = BA
Structure Type
------------------ = Culvert-Circular
------------------
No. Barrels = 1
Barrel Diameter = 3.0000 ft
Upstream Invert = 261.00 ft
Dnstream Invert = 260.00 ft
Horiz. Length = 78.00 ft
Barrel Length = 78.01 ft
Barrel Slope = .01282 ft/ft
OUTLET CONTROL DATA...
Mannings n = .0130
Ke = .5000
Kb = .007228
Kr = .5000
HW Convergence = .001
(forward entrance loss)
(per ft of full flow)
(reverse entrance loss)
+/- ft
INLET CONTROL DATA...
Equati on form = 1
Inlet Control K = .0098
Inlet Control M = 2.0000
Inlet Control c _ .03980
Inlet Control Y = .6700
T1 ratio (HW/D) = 1.154
T2 ratio (HW/D) = 1.300
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 = 264.96 ft ---> Flow = 42.85 cfs
At T2 Elev = 264.90 ft ---> Flow = 48.97 cfs
S/N: 621701207003 The John R> McAdams Company
PondPack Ver. 8.0058 Time: 5:19 PM Date: 6/28/2007

•
Type.... Outlet Input Data
Name.... SWMF #7
Page 1.09
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
Structure ID = TW
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES ...
Maximum Iterations= 30
Min. TW tolerance = .O1 ft
Max. TW tolerance = .Ol ft
Min. HW tolerance = .Ol ft
Max. HW tolerance = .Ol ft
Min. Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
•

S/N: 621701207003 The John R> McAdams Company
PondPack Ver. 8.0058 Time: 5:19 PM Date: 6/28/2007

•
r~
•
Type.... Composite Rating Curve
Name.... SWMF #7
Page 1.11
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engine er: J. ALDRIDGE, EI
Project Tit le: HIGHLAND CREEK
Project Commen ts:
***** COMPOSITE OUTFLOW SUMM ARY ** **
WS Elev, Total Q Notes
-------- -------- ----- --- Converge ------- --- --- ------------
Elev. Q TW E lev Error
ft
--
- cfs f t +/-ft Contrib uti ng Structures
----
-
266.50 -------
.00 -----
Free --- -----
Outfall --------
(no Q: ------
RI,SI ------------
,BA)
266.60 .02 Free Outfall SI,BA (no Q: RI)
266.80 .10 Free Outfall SI,BA (no Q: RI)
267.00 .14 Free Outfall SI,BA (no Q: RI)
267.20 .18 Free Outfall SI,BA (no Q: RI)
267.90 .21 Free Outfall SI,BA (no Q: RI)
267.60 .23 Free Outfall SI,BA (no Q: RI)
267.80 .26 Free Outfall SI,BA (no Q: RI)
268.00 .28 Free Outfall SI,BA (no Q: RI)
268.20 5.66 Free Outfall RI,SI,B A
268.90 15.49 Free Outfall RI,SI,B A
268.60 28.22 Free Outfall RI,SI,B A
268.80 43.28 Free Outfall RI,SI,B A
269.00 60.36 Free Outfall RI,SI,B A
269.20 79.13 Free Outfall RI,SI,B A
269.40 89.70 Free Outfall RI, BA (no Q: SI)
269.60 91.09 Free Outfall RI, BA (no Q: SI)
269.80 92.96 Free Outfall RI, BA (no Q: SI)
270.00 93.81 Free Outfall RI, BA (no Q: SI)
270.20 95.13 Free Outfall RI, BA (no Q: SI)
270.40 96.49 Free Outfall RI, BA (no Q: SI)
270.60 97.74 Free Outfall RI, BA (no Q: SI)
270.80 99.02 Free Outfall RI, BA (no Q: SI)
271.00 100.28 Free Outfall RI, BA (no Q: SI)
271.20 101.52 Free Outfall RI, BA (no Q: SI)
271.40 102.75 Free Outfall RI, BA (no Q: SI)
271.60 103.96 Free Outfall RI, BA (no Q: SI)
271.80 105.17 Free Outfall RI, BA (no Q: SI)
272.00 106.35 Free Outfall RI, BA (no Q: SI)
S/N: 621701207003 The John R> McAdams Company
PondPack Ver. 8.0058 Time: 5:19 PM Date: 6/28/2007

HMS * Summary of Results for SWMF #7
•
Project CTX-06070
Start of Run 16Feb07 0600
End of Run 17Feb07 0800
Execution Time 29Jun07 1340
Run Name POST [DESIGN) - Q2
•
Computed Results
Basin Model POST [DESIGN)
Met. Model Q2
Control Specs 1-min dT
Peak Inflow 79.810 (efs) Date/Time of Peak Inflow : 16 Feb 07 2005
Peak Outflow 22.261 (cfs) Date/Time of Peak Outflow 16 Feb 07 2018
Total Inflow 1.49 (in) Peak Storage 1.4948 (ac-f t)
Total Outflow 1.02 (in) Peak Elevation 268.51 (f t)
•

HMS * Summary of Results for SWME' #7
•
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 29Jun07 1340
Run Name POST [DESIGN] - Q10
•
Computed Results
Basin Model POST [DESIGN]
Met. Model Q10
Control Specs 1-min dT
Peak Inflow 135.18 (cfs) Date/Time of Peak Inflow 16 Feb 07 2005
Peak Outflow 85.449 (cfs) Date/Time of Peak Outflow 16 Feb 07 2010
Total Inflow 2.85 (in) Peak Storage 2.1883 (ac-f t)
Total Outflow 2.43 (in) Peak Elevation 269.32 (f t)
•

•
HIGHLAND CREEK
CTX-06070
Velocity Dissipator - SWMF #7
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 Manning's roughness number is
constant over the entire length of the pipe.
Flow Qlo (cfs) = 85.44
Slope S (%) = 1.28
Pipe Diameter Do (in) = 36
Manning's `n' = 0.013
Flow Depth (ft) = 3.00
Outlet Velocity (fps) = 12.09
NRCD Land Quality Section
NYDOT Dissipator Design Results
•
Pipe Diameter (ft) = 3.00
Outlet Velocity (fps) = 12.09
Apron Length (ft) = 24.00
d50 Stone Thickness
(inches) Class (inches)
4 A 9
8 B 22
-~ 10 1 22 ~
14 2 27
Width = La + Do
Width=24+3
Width (ft) = 27
Use NCDOT Class `1' Rip Rap
d50 =10"
24'L x 27'W x 22"Thick
J. ALDRIDGE, EI
6/29/2007

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 6/29/2007
Square Riser/Barrel Anti-Flotation Calculation Sheet
• Input Data =_>
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 = 7.00 feet
Concrete unit weight = 142.0 PCF
OD of barrel exiting manhole = 45.50 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 = 77.000 CF
Opening for barrel = 5.646 CF
Opening for drain pipe = 0.175 CF
Note: NC Products lists unit wt. of
manhole concrete at 142 PCF.
Total Concrete present, adjusted for openings = 95.180 CF
• Weight of concrete present = 13516 lbs
Amount of water displaced by Riser Structure =_>
Displacement by concrete = 95.180 CF
Displacement by open air in riser = 175.000 CF
Displacement by trash rack = 61.740 CF
Total water displaced by riser/barrel structure = 33L920 CF
Weight of water displaced = 20712 lbs
Calculate amount of concrete to be added to riser =_>
Safety factor to use = 1.15 (recommend L IS or higher)
Must add = 10303 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 = 148.850 CF of concrete
Standard based described above = 24.000 CF of concrete
• Therefore, base design must have = 172.850 CF of concrete

HIGHLAND CREEK SWMF #7 J. ALDRIDGE, EI
CTX-06070 6/29/2007
• Calculate size of base for riser assembly =_>
Length = 9.000 feet
Width = 9.000 feet
Thickness = 26.0 inches
Concrete Present = 175.500 CF OK
Check validity of base as designed =_>
Total Water Displaced = 483.420 CF
Total Concrete Present = 246.680 CF
Total Water Displaced = 30165 Ibs
Total Concrete Present = 35029 lbs
Actual safety factor = 1.16 OK
Results of design =_>
•
Base length = 9.00 feet
Base width = 9.00 feet
Base Thickness = 26.00 inches
CY of concrete total in base = 6.50 CY
Concrete unit weight in added base >= 142 PCF

aiv • VLVi•1L v WVV LL Il Vi\IJ~ 1 11\111Y111/LVl\V-
S 4b'G L Vl 1
C4LCUI::~'I'E ~'QLtii~-IE QF PYR=111~ID ~~'ITH I~TI)I~'IDL~AL V4'IDTHS A~TD LEI~GTL~S
Fnttr a.tl knc-3v~i val~~cs in the farit~ helo«~ and press the. "CAI~CL`L~TE" trutton.
•
~.':
•
+.3 :2 _~.~, ~..'f,}( 1. i1:~ii-a ._.._-lY"li
C,
http://abe.msstate.edu/ fto/tools/vol/pyrarnidlong.html 5/3/2007

HIGHLAND CREEK SWMF #7 Level Spreader Outlet Velocity Calculations
CTX-06070
1" storm peak flow rate = 0.04 cfs
Determine depth of the flow over level spreader weir:
Q = C~,yLH3iz
H = (Q/CWL)z~3
CW = 3.0
L = 15.75 ft
Q = 0.04 cfs
H = 0.009 ft
~A7 WEIR - 2/3 H = 0.006 ft
•
Determine velocity offlow over level spreader weir:
Q = VA
V = Q/A
= Q/(1_.*HAT WEIR)
Q = 0.04 cfs
L = 15.75 ft
HAT WEIR - 0.006 ft
V = 0.43 ft/sec
Therefore, the approximate velocity over the level spreader weir is 0.45 ft/sec.
J. ALDRIDGE, EI
6/29/2007
•

HMS * Summary of Results for SWMF #7
Project : CTX-06070
. Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 29Jun07 1411
Run Name POST [DESIGN] - Q1"
Basin Model POST [DESIGN]
Met. Model 1" STORM
Control Specs 1-min dT
Computed Results
Peak inflow 0.21443 (efs) Date/Time of Peak Inflow 16 Feb 07 2016
Peak Outflow 0.037342 (cfs) Date/Time of Peak Outflow 17 Feb 07 0800
Total Inflow 0.04 (in) Peak Storage 0.079313(ac-f t)
Total Outflow 0.01 (in) Peak Elevation 266.64 (f t)
•

•
FINAL DESIGN OF STORMWATER
MANAGEMENT FACILITY #1 D

HIGHLAND CREEK
CTX-06070

/~
// \
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~i0 / I / 0 / 30 ~ ,E~ / 120
/ ~ i /,,.
1 inch = 60 ft.

~/

~/ ~\
L I
__~U\ \ \
~ `~ ' ~~
~ ~
~ ~
PROJECT N0. CTX-06070
HIGHLAND CREEK THE JOHN R. McADAMS
INC
COMPANY
~ ~LENnesE: POND EXHIBITS ,
.

~
SCALED
"
'
NORTH CAROLINA
RALEIGH ENGINEERS/PLANNERS/SURVEYORS
1
=60 , RESEARCH TRIANGLE PARK, NC
~ Sw~ # 10 ~~ P.O. HOX 14005 ZII' 27709-4005
~' DA7~` 06-13-2007 [phone]

HIGHLAND CREEK SWMF #10 J: ALDRIDGE, EI
CTX-06070 5/2/2007
• Stake-Storage Function
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contouz Stage Area Area - . Volume Volume w/ S-S Fxn
(tcet) (feet). (SF) (SF) (CF) (CF) (feet).
?72.00 0:00 28219
274.00 2.00 ~ 34024 31122
~- 62243_:
~~
~ 62243_
`~`
~__ 2:02_
.___
_____
_~ 276.00~~ _
~-_4:00 m_
. ~~39998 ~~
___-------__
_ _
a~_37011
_.___.-----.__ 74022
_.____w.~-.--- 136265
__.__________.__.~._ 3.93
_________~~__
____~ _.___
278 OU ._._ __ ..___
.
6.00 .
46199 43099 861.97 222462
_
~ 5:95
~
_
_
280.00 ~ ~ 8.00 .._ _._. 52625 494.12 98824 321286 8.13
~, ,..
•
Storage vs. Stage
3:50000
I _. __..._._.~~.. _... ._~
I
300000
~ nse
y = 27126x
250000 RZ = 0.9993 , S
{
v 200000 ~
a
rn
t50000
o
i
~ 1D0000-
i
50000
"
0
0:00 2.00. 4.00. 6.00 8:00 1`0.00
Stage{feet)
~-
- KS= 27126
b= 1.1798'.
•

HIGIiLAND CREEK SWMF #10 J. ALDRIDGE, EI
CTX-06070. 5/2/2007
• => Stage -Storage Fu~tction
Ks = ''7126
b= L1-98
•
Elevation Storage
~feet~ ~cf~ (acre-feet 100-YR
272.00 0 0.000 y~..,e
272.20
" 4062 I 0.093
272.40
_. 9202 _ 0 21 I - _. _______~~
272.60 14847 ~ 0.341 ~

272.80
20847. ~`3" 0479 _
27_3.00 27126 i 0.623

273.20
_ Y^
33636 ~ 0.772
~
273.40 4034m5 ~~~-~~ _ 0.926 F~ ~"""~'___
Y~273.60
_ 47229 ~_ 1:084
mm
~~ ^-~
_
-_-_~
_273.80
~ _54270
1.246

274.00
~6.1453 j 1:4{ 1~ _
_
__
`
274.20
~274.40~ _68766 1,579
76201~!~~-L749
~w^m~ ~_______.__
~~_____
274.60
. 83747 1_:923
a 1

274.80 _.~ ...___.__..._
91399 s 2.098_ _._.___._______
~

275.00 _
99150 ~~ 2.276 ~~~~
1
_
275.20 ~ !06995 2.456 I
__ _
275.40 f F14928a ; _ 2.638
27
5.60 122945 f 2.822
_
_
_ - _.~__
_ _ 275.80 ~__.________7____<__~..
„_t310~k3 3.008 ~
~ ___m_
___.
276
00 `139218
3
196
.
_
W_ .
--- '""""_____„__.._
27620 ~ 147467 ~ 3-.385 ~
276.40 _
155787 , 3.5T6 ~

276.60
164175 3.769 ~ _
0-:000
276:80 172629 ?~ 3.963 _ 0.194

277:00
t 8 l t 47 ~ 4. k 59
T __,
rv
0.390
27720 189726 ~
4356
~
~ 0.587
277.40_ I
277
60 198364
'
4.554
---
X
0706
~[ 0.7_85
.
_[ 2
.1
4.753
._.m..._..~_..._".~__._ _0.985
~
277.80 i 2 f 5813 4.954
~ L 185
_
27
8.00~~ _
~ 224620-µµ~ 5.157W ! 1.388
_
278:~20 e
_233480 5.360 ~ _
_L591
_ 278.40 ~ 242391 5.565 _w( ~ 1.79fi
~
278.60 ~

278.80 251353 5.770
_...__.~
260363 ! 5-_977 2.001

2.208,
27
9.00 269422 s 6.1$5 2.4t6
_
27920 278527 6394. .2.625
_
279.
40 287677 ~ 6.6
04 ~ 2.83.5
_
_
~ _
w
~~
_ 279.60
j _ 296872 ;
_6.813 ~ 3.046
279.80 061} t ~
3
7.027 ~ 3.258
280.00 ~
_
315392 7.240 ~ 3.470
•

HIGHLAND CREEK SWMF #10 J. ALDRIDGE, EI
CTX-06070 6/14/2007
Extended Detention Wetland Sizing
• Source: Stormwater Best Management Practices. NCDENR: Division of Water Quality -
Water Quality Section. April 1999.
Enter the drainage area characteristics =_>
Drainage area = 26.85 acres @ 52.4% impervious
Estimate the surface area required at pond normal pool elevation =>
Extended Detention Wetlands are based on a normal pool depth of = 3.0 feet (Per NCDENR Handbook)
From the DWQ BMP Handbook (4/99), the required SA/DA ratio =_>
•
Total drainage area to pond = 26.85 acres
Total impervious area to pond = 14.07 acres
Note The wetland must be sized to treat all impervious surface runoff draining into the pond, not just the impervious surface from
on-site development.
3.0 3.0 4.0
Lower Boundary => 50.0 2.06 1.73
Site % impervious => 52.4 2.14 2.14 1.80
Upper Boundary => 60.0 2.40 2.03
Therefore, SA/DA required = 2.14
Surface area required at normal pool = 25049 ft2
= 0.58 acres
Surface area provided at normal pool = 28219 ftz
CJ

•
HIGHLAND CREEK -PHASE 2/4
CTX-06070
WATER QUALITY VOLUME
CALCULATIONS
SWMF #10
=_' I)t~t~~riRiiurtiuit n~' li ~~itrr ~)nalitl~~ F ~oltiine ~1~~'~v~

where,
WQv =water quality volume (in acre-ft)
Rv= 0.05+0.009(I) where I is percent impervious cover
A =area in acres
P =rainfall (in inches)
Input data:
Total area, A = 26.85 acres
Impervious area = 14.07 acres
Percent impervious cover, I = 52.4
Rainfall, P = 1.0 inches
Calculated values:
Rv = 0.52
WQv = 1.17 acre-ft
= 50840 cf.
•
_: > 1)rarrrlonvt Culciilutrnn~
Per the NCDENR handbook "Stormwater Best Management Practices" (Apri11999), drawdown of the
Stormwater runoff shall occur within 5 days
Input data:
WQv = 50840 cf.
Stage /Storage Data:
Ks = 27126.0
b = 1.1798
Zo = 272.00
Vol. in 1.0" Rainfall = 50840 cu. ft
Calculated values:
Depth of WQv in Basin = 1.70 ft
= 20.44 inches
EL = 273.70 ft
B. FINCH, PE
6/28/2007
•

HIGHLAND CREEK
CTX-06070
Inverted Siphon Design Sheet
•
•
D orifice =
# orifices =
Ks =
b=
Cd siphon =
Normal Pool Elevation =
Volume @ Normal Pool =
Orifice Invert =
WSEL @ 1" Runoff Volume =
SWMF #10
3 inch
1
27126
1.1798
0.60
272.00 feet
0 cf
272.00 feet
273.70 feet
J. ALDRIDGE, EI
6/28/2007
WSEL
(feet) Vol. Stored
(c Siphon Flow
(cfs) Avg. Flow
(cfs) Incr. Vol.
(cf) Incr. Time
(sec)
273.70 50840 0.296
273.56 45735 0.282 0.289 5105 17641
273.41 40715 0.268 0.275 5020 18255
273.26 35787 0.252 0.260 4927 18968
273.12 30962 0.235 0.244 4826 19812
272.97 26248 0.217 0.226 4713 20834
272.83 21661 0.198 0.207 4587 22114
272.68 17218 0.176 0.187 4443 23793
272.53 12944 0.151 0.163 4274 26155
272.39 8878 0.121 0.136 4066 29902
272.24 5084 0.080 0.100 3794 37810
Drawdown Time = 2.72 da s
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 = 0.789 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of 3" orifice = 0.049 sf
Q = 0.2100 cfs
Drawdown Time =Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.80 days
Conclusion : Use 1 - 3" Diameter PVC Inverted Siphon to drawdown the accumulated
volume from the 1.0" storm runoff, with a required time of about 2.75 days.
•

Type.... Outlet Input Data Paqe 1.01
Name.._. SWMF #10
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title.... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
REQUESTED POND WS ELEVATIONS:
Min. Elev.= 272.00 ft
Inurement = .20 ft
Max. Elev.= 280.00 ft
OUTLET CONNECTIVITY
---> Forward Flow Only (Upstream to DnStream}
G--- Reverse Flow Only (DnStieam to Upstream)
---> Forward and Reverse Both Allowed
Structure No. Outfall El, ft E2, ft
Inlet Sax RI ---> BA 276.600 280.000
Orifice-Circular SI ---> 8A 272.000 280.000.
Culvert-Circular BA. ---> TW 269.000 28.0.000
TW SETUP, DS Channel

C
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:50 PM Date: 5/2/2007

•
Type.... Outlet Input Data
Name.... SWMF #10
Page 1.02
File.... X:\Projects\CTX\CTX-060.70\Storm\Deaign Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET. STRUCTURE INPUT DATA
Structure ID = RI
Structure Type = Inlet Box
-------------
------
-----------------
# of Openings = 1
Invert Elev. = 27.6.60 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
Structure ID = SI
Structure Type = Orifice-Circular
# of Openings = 1
Invert Elev.. = 272...00 ft
Diameter. _ .2500 ft
Orifice- Coeff. _ .600

•
S/N: 62I7012070C3 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:50 PM Date: 5/2/2007

•

Type.... Outlet Input Data Page 1.03
Name.... SWMF #10
File..... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET. STRUCTURE INPQT DATA
Structure ID BA
Structure Type = Culvert-Circular
No. Barrels = 1
Barrel Diameter = 3.0000 ft
Upstream Invert 269.0-0 ft
Dnstream Invert = 26$.00 ft
Horiz. Length = 60.00 ft
Barrel Length = 60.01 ft
Barrel Slope = .01667 ft/ft
OUTLET CONTROL DATA...
Mannings s = .0130
Ke = .5D00 (-forward entrance loss)
Kb = .007228 (per ft of full flow)
Kr = .5000 (reverse entrance loss)
HW Convergence- _ .001 +/- ft
INLET CONTROL DATA.....
Equation form = 1
Inlet Control K = .0098
Inlet ContrbL M = 2_,0000
Inlet Control e = .03980
Inlet Control Y = .6700
T1 ratio (HW/D) = 1.152
T2 ratio (HW/D) = 1.298
Slope Factor. _ -.500
Use unsubmerged inlet control Form L equ. below T1 elev.
Use submerged inlet control Form l equ. above T2 elev..
In transition zone between unsubmerged and submerged inlet control,.
interpolate between-flows at T1 & T2...
At Tl Elev = 272.46 ft ---> Flow = 4.2.85 cfs
At T2 Elev = 272..90 ft ---> Flow 48..97 cfs
•
E ...:
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:50 PM Date: 5/2/2007

•
Type.... Outlet Input Data
Name:... SWMF #10
Page 1.04
File.._. X:\Projects\CTX\CTX-06070\Storm\Design Eiles\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
OUTLET STRUCTURE INPUT DATA
' Structure ID = TW '
Structure Type = TW SETUP, DS Channel
------------------------------------
FREE OUTFACE CONDITIONS SPECIFIED
CONVERGENCE TOLERANCES...
Maximum Iterations= 30
Min. TW tolerance = .O1 ft
Max.. TW tolerance = .Oi ft
Min.. HW tolerance = .Ol ft
Max. HW tolerance = .O1 ft
Mina Q tolerance = .10 cfs
Max. Q tolerance = .10 cfs
•
•
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:50 PM Date: 5/.2/2007

•
Type..... Composite Rating Curve
Name.... SWMF #10
Page 1.14
File.... X:\Projects\CTX\CTX-06.070.\Storm\Design Files\SWMF DESIGN:PPW
Title... Project Date: 2 /16/2007
Project Enginee r: J. ALDRIDGE; EI
Project Titl e: HIGHLAND CREEK
Project Comment s:
***** COM POSITE OUTFLOW SUMM ARY ****
WS Elev, Total Q Not es
-------- ------- ------ --Converge ------ - --- --- -----------
Elev. Q TW El ev Error
ft cfs ft +/-ft Contrib uting Structures
272.00 .00 Free Outfall (no Q: RI, SI, BA)
272.20 .06 Free Outfall SI,BA (no Q: RI}
272.40 .12 Free Outfall SI,BA (no Q: RI)
272..60 .16 Free. Outfall SI,BA (no Q: RI)
272.8.0 .19 Free Outfall SS,BA (no Q: RI)
273.00 .22 Free Outfall SI,BA (no Q: RI)
273.20 .24 Free Outfall SL, BA (no Q; RI)
273.40 .27 Free Outfall SI,BA (no Q: RI)
273.60 .29 Free. Outfall SI,BA (no Q: RI)
273.80 .31 Free Outfall SI,BA (no Q: RI)
274..00 .32 Free Outfall SI,BA (no Q: RI)
274.20 .34 Free Outfall SI,BA (no Q: RI)
274..40 .36 Free Outfall SI,BA (no Q: RI}
274..60 .37 Free Outfall SI,BA (no Q: RI)
27.4.8.0 .39 Free Outfall SI,BA (no Q: RI)
275.00 .40 Free Outfall SI,BA (no Q: RI)
275.20 .41 Free Outfall SI,BA (no Q: RI)
275.40 .43 Free Outfall SI,BA (no Q: RI)
275.60 _44 Frse Qutfall SI,BA (no Q: RI)
275.80 .4-5 Free Outfall SI,BA (no Q: RI)
276.00 .47 Free Qutfall SI,BA (no Q: RI)
276.20 ,48 Free Outfall SI,BA (no Qc RL}
276..40 .49 Free Outfall SL, BA (no Q: RI)
2.76.60 .50 Free Outfall SL, BA (no Q: RI}
276..80 5.8.8 Free Outfall RI,SI,B A
277.00 15.70 Free Outfall RI,SI,BA
277.20 28..42 Free Outfall RI,SI,BA
277.4D 4.3.45 Free Outfall RI,SI,BA
277.60 60.45 Free Outfall RI,SI,BA
277.8-0 79.19 Free Outfall RI,SS,BA
278.00 93.84. Free Outfall RIBA (no QL SI)
278.20 95.18- Free OutfaTl RI, BA (no Q: SI)
278.40 96.49 E'ree Outfall RI, BA (no Qc SI}
278.60 97.78 Free Outfall RI, BA (no 4: SI}
S/N: 621701207003 The Sohn. R. McAdams Company
PondPack Ver. 8.0058 Time: 2:51 PM Date: 5/2/2007

•
Type.... Composite Rating Curve
Name.... SWMF #10
Page 1.15
File.... X:\Projects\CTX\CTX-060.70\Storm\Design Files\SWMF DESIGN.PPW
Title.... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
***** COMPOSITE OUTFLOW SUMMARY ****
WS E1ev, Total Q Notes
-------- -------- ------ -- Converge ---- -. ----- --
Elev. Q TW El ev Error
ft cfs ft +/-ft Contributin g Structures
278,.80 49.05 Free Outfall RIBA (no Q. SI)
279.00 100.31 Free Outfall RI, BA (no Q: SI)
279.20 101.55 Free Outfall RI, BA (no Q; SI)
279.40 102.78 Free 0utfa1l RI, BA (no Q: SI)
279:6-0 104.00 .Free Outfall RI, BA (no Q: SI)
279.80 105.20 Free Outfall RI, BA (no Q: SI)
280..00 10b.38 Free Outfall RI, BA (no Q: SL)

S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:51 PM Date: 5/2/2007

HMS * Summary of Results for SWMF #10
•
Project CTx-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1443
Run Name POST [DESIGN] - Q2

Basin Model POST [DESIGN]
Met. Model Q2
Control Specs 1-min dT
Computed Results
Peak Inflow 85.106 (efs)
Peak Outflow 0.48941 (efs)
Total Inflow 1.79 (in)
Total Outflow 0.21 (in)
Date/Time of Peak Inflow 16 Feb 07 2005
Date/Time of Peak Outflow 17 Feb 07 0800
Peak Storage 3.5292 (ac-ft)
Peak Elevation 276.39(ft)
•

HMS * Summary of Results for SWMF #10
Project CTX-06070 Run Name POST [DESIGN] - Q10
• Start of Run 16Feb07 0800 Basin Model POST [DESIGN]
Snd of Run 17Feb07 0800 Met. Model Q10
Execution Time 14Jun07 1448 Control Specs 1-min dT
Computed Results
Peak Inflow 133.10 (cfs) Date/Time of Peak Inflow 16 Feb 07 2004
Peak Outflow 18.798 (efs) Date/Time of Peak Outflow 16 Feb 07 2033
Total inflow 3.32 (in) Peak Storage 4.1517 (ac-f t)
Total Outflow 1.64 (in) Peak Elevation 277.05(ft)
•
•

HMS * Summary of Results for SWMF #10
~:
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1448
Run Name POST [DESIGN] - Q50
Basin Model POST [DESIGN]
Met. Model Q50
Control Specs 1-min dT
•
Computed Results
Peak inflow 185.44 (efs) Date/Time of Peak Inflow 16 Feb 07 2004
Peak Outflow 74.255 cfs) Date/Time of Peak Outflow 16 Feb 07 2015
Total inflow 4.99 (in) Peak Storage 4.9563 (ac-ft)
Total Outflow 3.31 (in) Peak Elevation 277.89(ft)
F(,~W t~D 'T~ C~-uLA'i~
YEuacrlY 'D[ss~~-r°~

HMS * Summary of Results for SWMF #10
Project CTX-06070 Run Name POST - QTHIRDPMP
. Start of Run 16Feb07 0800 Basin Model POST [DESIGN]
End of Run 16Feb07 1400 Met. Model QTHIRDPMP
Execution Time 14Jun07 1449 Control Specs 5-min dT
Computed Results
Peak Inflow 178.60 (of s) Date/Time of Peak Inflow 16 Feb 07 1025
Peak Outflow 86.394 (cfs) Date/Time of Peak Outflow 16 Feb 07 1040
Total Inflow 7.60 (in) Peak Storage 6.4970(ac-f t)
Total Outflow 5.75 (in) Peak 8levation 279.44(ft)
•
•

HIGHLAND GREEK..
CTX-06074
•
Velocity Dissipater - SWIVIF #10
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 [he Manning's roughness number is
constant over the entire length of the pipe.
Flow. QSa (cfs) = 74.26
Slope S (%) = 1:67
Pipe Diameter Do (in) = 36
Mannng's `n' = 0.013
Flow Depth (ft) = 2.15
Outlet Velocity (fps) = 13.72
NRCD Lanrl Quality Section
NYDOT Dissipater Design Results
•
Pipe Diameter (ft) = 3:00
Ouilet Velocity (fps) = 13.72
Apron Length (ft) =24
d50 Stone Thickness
(inches) Class (inches)
4 A 9
8 B 22
~ l0 1 22 f-
14 2 27
Width = La + Do
Width.=24 + 3
Width (ft)= 27
Use NCDOT Class `1' Rip Rap
d50 =10"
24'L x 27'W x 22"Thick
J. ALDRIDGE, EI
5/3/2007

HIGHLAND CREEK
CTX-06070
SWMF #10
Square R.iser/Barrel Anti-Flotation Calculation Sheet
• In ut Data =>
P
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= 7:60 feet
Concrete. unit weight = 142.0 PCF
OD of barrel exiting manhole= 45.50 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:
:~lotr. NC Products lists unit lvt. oi'
ntanhule ~ixrcrc;te at t~2 PC.'F.
Base of Riser = 24.000 CF
Riser Walls = 83.600 CF
Adjust for openings: .,
Opening for barrel = 5.646 CF
Opening for drain pipe = 0:175 CF
• Total Concrete present, adjusted for openings = 101.780 CF
Weight of concrete present = 14453 lbs
Amount of water dis~lacec! by Riser Structure =>
Displacement try concrete = 101.780 CF
Displacement by open air in riser = 190.000 CF
Displacement by trash rack = 61.740 CF
Total water displaced by riser/barrel stnicture = 353.520 CF
Weight of water displaced= 22060 tbs
Calccrlafe amount of concrete to be added to riser =>
Safety factor to use = 1..15 i rr:,c~tum~nd L.IS er tiigttei )
Must add = 10916 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 = 157.704. CF of concrete
Standard based described above = 24.000 CF of concrete
• Therefore, base design must have = 181.704 CF of concrete

.HIGHLAND CREEK SWIVIF #10 J. ALDRIDGE, EI
GTX-060?0 5/3/2007
`` • Calculate size of base for riser assembly __>
Length = 9.000 feet
Width = :9.000 feet -
Thickness = 27.0: inches
Concrete Present = 182.250 CF +DK
Check validity of base as designed =>
Total Water Displaced = 511-.770 CF
Total Concrete Present = 260.030 CF
Total Water Displaced = 319341bs
Total Concrete Present = 36924 lbs.
Actual safety factor = 1.16 DK
Results of design. =>
•
Base length= 9'.00 feet
Base width= 9,00 feet-
- Base Thickness = 27.00 inches
CY of concrete total in -base = 6.75 CY
Concrete unit weight in added base>= 142 PCF
•

ABE VOLUME CALCULATORS,.PYRAMIDLONG Page 1 of 1
~'1GCL~L C'I`E ~'(3LtiI~1~ {}F P'Y'R~~~t'IEfl ~~I'TH i='~II~I~'II~€.~,Il ~~'lI)'#'IS =~~) I.:~~"T~IS
Enter all l,•,nc~~~n tiralues in the #~~~-rn tint©~ and press tie "C':~I,t;C'I>A~I~I~" h~tt#:t~~~.
•
»f .~; Y~Y . `.
~~yr ~~ ~ n
r;:~1 ~ ,~~~,tr~
i

{7C.` 7C; ~+.I.I!' ~~Cf~tiitil't? }jt{iTi:
•
http://abe.msstate.edu/~fto/tools/vol/pyramdlong.html 5/3/20Q7

HIGHLAND CREEK SWMF #10 Level Spreader Outlet Velocity Calculations
CTX-06070
1" storm peak flow rate = 0.08 cfs
Determine depth of the flow over level spreader weir:
Q = CWLH3iz
H = (Q/CWL~zis
CW = 3.0
L = 15.75 ft
Q = 0.08 cfs
H = 0.014 ft
HAT WEIR = 2/3 H = 0.009 ft
Determine velocity offlow over level spreader weir:
Q = VA
V = Q/A
= Q/(L*HAT WEIR
Q = 0.08 cfs
L = 15.75 ft
HAT WEIR - O.OOI ft
V = 0.54 ft/sec
Therefore, the approximate velocity over the level spreader weir is 0.55 ft/sec.
J. ALDRIDGE, EI
6/ 14/2007

HMS * Summary of Results for SWMF #10
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1615
Run Name POST [DESIGN] - Q1"
Basin Model POST (DESIGN]
Met. Model 1" STORM
Control Specs 1-min dT
Computed Results
Peak Inflow 2.8323 (efs)
Peak Outflow 0.084317 (cfs)
Total Inflow 0.10 (in)
Total Outflow 0.03 (in)
Date/Time of Peak Inflow 16 Feb 07 2000
Date/Time of Peak Outflow 17 Feb 07 0800
Peak Storage 0.14885 (ac-ft)
Peak Elevation 272.28(ft)

•

•
100-YEAR STORMROUTING CALCULATIONS
•

HIGHLAND CREEK
CTX-06070

HIGHLAND CREEK SW14IF #1 J. ALDRIDGE, EI
C"I'X-06070 S/3/2007
-~ Stage - Storage Frurction
• Ks= ~S1IS
b= t.13i6
Zo= "_'7.00
Elevation Storage
~feetJ ~cf~ nacre-feet 100-YR

275.00 _
0 -:KP.~
0.000
275.20 40_38
._
-~ 0.0_93
~. ~
_...._.~.___
275.40 8872
~-"~
~~-~ 0._204
~~~
~ ~~~~
275.60 ` 14061 0.323
'
275.80_
_ 194_93
~~~~ 0.448
~
~~~~~~_~~
27_6.0_0
-- 25 I I S 0 S77 ~~
276.20
~ 30802
~~ 0 709
~ ~ ~~~--~~_~~
276.40 36802 ~ 0.845
276.60 42828
~~ 0 983 _....._._~_~
276.80 48958
_. ~ 1.124
__. _.
277.00 SS 180 I X67
~
~~
277.20 61488_
_- 14 i ~
~
~ ___ _...
277.40 67874 I.
SS8
277.60
~.
~ 74332_
~~~
~ 1._706
~~_.
~~~~~
__..___.__.~
277.80_
_ 80859 _
~j ~
1.856
'
~~ ~"~~~~~
278.00
_, 87448
_.___..~~_._ 2.008
:.w..____...._. _.,._ ._.__..___.___.
278.20 _ 94098 2.160
- _
_
278.40.
~
100805
~ 2 314
~
~ _
" a
_ 278.60 _107565
. 2.469_ i
!
~;
_278.80
m_~ ] 14376
~
- 2 6_26
~
279.OO 121236 2.7_83
'
_" __ .,______
279.20 128143 ~ 2.942
279.40 I3S09S 3101
•
279.60
142089
3 ~6~
- '-^ _-
279.80 149125 w
3 423
280.00 ~ 1S6201 3 S86 0.000
280.20 t 163315 3 749 0.163
____..,.._
280.40-
~- f_.._....,...
~ 170467_
~ _ 2. __
3913
~
~ ~ ....,...~~___.__._
0:3.27__
280.60 1~77654
~ - 4 078 0.4
93

28
0.$0
t 184877
4.244 _
"
0.6
58
_
.
281.00
~-~~~1921~33
4 4l I~~ _
_
_
0.825 -~
281.20 ~ 199422 4 S78 0.992
281
40 206743 6 _
4
74 _
L 460
.
2$1.60 t 214095 .
_
~ 4.915 ~ _
~ 1.329
281.80 ~ 221478 ! 5.084_ L499
-~~
282.00 228890 S 2~5 L669
282.20 236331 5 425 1.840
282.40
~~~ 243799
~~~ S S97 2.OI
282.60 ` 251296 S 76_9 _2.183_
_-~
282.80 258819 ' S 942 ~ 2.356
283.00 266368 b I IS _
2.529
•

•
Type.... Composite Rating Curve
Name.... SWMF #1 - Q100
Page 1.07
File..... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
***** COMPOSITE OUTFLOW SUMMARY ****
•
•
WS Elev, Total Q Notes
-------- -------- ------ -- Converge ------ `
Elev. Q TW El ev Error
ft cfs ft +/-ft Contributing Structures.
280.00 .00 Free Outfall (no Q: RIBA)
280.20 5.37 Free Outfall RI, BA
280.4.0 15.18 Free Outfall RI, BA
280.60 27.89 Free Outfall RI, BA
280.80 42.93 ,Free Outfall RI, BA
281.00 60.00 Free Outfall RI, BA
281.20 78.87 Free Outfall RIBA
281.4.0 96.54 Free Outfall RI, BA
281.60 97.84 Free Outfall RIBA
281.80 99.11 Free Outfall RI, BA
282.00 100.36 Free Outfall RI, BA
282.20 101.61 Free Outfall RI, BA
282.40 102.84 Free. Outfall RI, BA
282.60 104.05 Free Outfall RI, BA
282..80 105.25 Free Outfall RI, BA
283.00 106.44 Free 0utfa1l RI, BA
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:94 PM Date: 5/2/2007

HMS * Summary of Results for SWMF #1
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1711
Run Name POST - Q100
Basin Model POST [DESIGN] - WC
Met. Model Q100
Control Specs 1-min dT
Computed Results
Peak Inflow 186.29 (cfs)
Peak Outflow 101.78 (efs)
Total Inflow 6.20 (in)
Total Outflow 6.18 (in)
Date/Time of Peak inflow 16 Feb 07 2004
Date/Time of Peak Outflow 16 Feb 07 2011
Peak Storage 1.8630 (ac-ft)
Peak Elevation 282.23(ft)
•
•

•
•
HIGHLAND CREEK
C'I'X-06070
SWMF #2
_> Stage -Storage Function
Ks = 14034
b= 1.1859
Elevation ' Storage m~
(feet ~cfJ nacre-feet 100-YR
278.00 0 0.000
278.20 2081 j 0.048 j

278:40 __ ___
4734~t;~0.109
278.60 7658 i 0.176 ._..._.._.,...~.~_
__
278.80 1
~ -~
10771 _ t 0.247
279.00 _ 14034 ! 0 223
279.20
~ t 742 l 0.400
279.40
279.60
279.80 20916 ? 0.480 `•
24505 ~ 0.563
28178 ~ 0:647 _~_~ ~_-.._._._,
.1 __~_ _. __.
~
_280.00
-~ 31928
~ 0.733
~ ~" _.._.
280:20_
~_ 280.40_ 35749 0.821.
39635 0,910 ` ~~~ _~ ~~
._ _. _.
.
280:60 ~
43581 ~ 1.000
_
280
80 ~ ,,__,._ .
092
~ 47585 i 1
.
_
281.00
_ _... .
51642 L 186
~..__..._ ~_---____. E _. _.. _ ...
281.20
281:40 55749 1.280
59405„__„_T .__1:375 _
--__.... .
28 {:60 64 C06 j 1472 1
281:80 569
~ 6835.1 -~'~ 1:
282.00 .
~ 72638. ? 1.668 ~
~
282.20 w L767
~ 76965 j

~282.40rr __
_._..._ _._.__.._.
81330~~ 1,857 _ ' -
=
282.60 _ __
85733 _ 1 968 (1.000
~
~~
~
282:80 _
90171 ~ 2 070 ~.1 m
~
283.00
~_.. 94643 ? 2.173 020
L_ ~ ~._ w.. ;_._... ~.__ . ._
~
_~
~~
283.20.
40
28
3 308
99149__ 2.276
0
412
103688 ~ 2 380
0
_
.
283.60 ~
.
3 _ ._~
E 108257 _'
2.4
85 i 0.517
283.80 ~
_
1.128.58 --- 2.591 0.623
" __
284.00 l 17487 ? 2.697 0.79
_
284.20 ~ ~ 122146
2.804 ~ 0.836
284.40
~_~. _
126832 ;~ 2.912 ~ 0.944
_w _. _._
284.60 131546 ~ 3.020 1:052
. -
284:80 ~
~~- c. ____ 1 __ _.
~ 136287 j 3 12_9_ ~ 1.161
-
- _
~~
285.00 r
L270
! 141053 i 3.23'8
J. ALDRIDGE, EI
5/3/2007
•

Type.... Composite Rating Curve
Name.... SWMF #2 - Q100
Page 1.07
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
• Project Comments:
***** COMPOSITE OUT FLOW .SUMMARY *'***
WS E1ev, Total Q
Elev. Q
ft cfs
282.60 .00
282.80 5.37
283.00 15.18
283.20 27.89
283.40 42.93
28.3.60 69.84
283.80 65.76
284.00 66.67
289.20 67.58
289.40 68.47
284.60 69.39
284.80 70.21
285.00 71.07
•
_w ...
•
Notes
-------- Converge -------------------------
TW Elev Error
ft +/-ft Contributing Structures
Free Outfall (no Q: RI, BA)
Free Outfall RIBA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall R1,BA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RI, BA
Free Outfall RIBA
Free Outfall RI, BA
S/N: 621701207003 The John R. McAdams Company
PondPack Ver. 8.0058 Time: 2:47 PM Date: 5/2/2007

HMS * Summary of Results for SFTMF #2
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1711
Run Name POST - Q100
Basin Model POST [DESIGN] - WC
Met. Model Q100
Control Specs 1-min dT
Computed Results
Peak Inflow 102.07 (efs)
Peak Outflow 67.003 (efs)
Total inflow 6.44 (in)
Total Outflow 6.42 (in)
Date/Time of Peak Inflow 16 Feb 07 2004
Date/Time of Peak Outflow 16 Feb 07 2009
Peak Storage 0.76821(ac-f t)
Peak Elevation 284.07(ft)
•
•

lJ
HIGHLAND CREEK
CTX-06070
SWMF #7
_> Stage -Storage Function
Ks = 29839
b= 1.1205
Zo = 266.50
Elevation
[feet] Storage
[cfJ [acre-feet] 100-YR
266.50 0 0.000
266.60 2261 0.052
266.80 7743 0.178
267.00 13724 0.315
267.20 20009 0.459
267.40 26516 0.609
267.60 33202 0.762
267.80 40037 0.919
268.00 47000 1.079 0.000
268.20 54076 1.241 0.162
268.40 61253 1.406 0.327
268.60 68522 1.573 0.494
268.80 75875 1.742 0.663
269.00 83306 1.912 0.833
269.20 90809 2.085 1.006
269.40 98379 2.258 1.180
269.60 106012 2.434 1.355
269.80 113705 2.610 1.531
270.00 121454 2.788 1.709
270.20 129257 2.967 1.888
270.40 137111 3.]48 2.069
270.60 145014 3.329 2.250
270.80 152963 3.512 2.433
271.00 160957 3.695 2.616
271.20 168993 3.880 2.801
271.40 177072 4.065 2.986
271.60 185190 4.251 3.172
271.80 193346 4.439 3.360
272.00 201540 4.627 3.548
J. ALDRIDGE, EI
6/28/2007
•

Type.... Composite Rating Curve
Name.... SWMF #7 - Q100
Page 1.09
File.... X:\Projects\CTX\CTX-06070\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/16/2007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
•
•
•
WS Elev, Total Q
----------------
Elev. Q
ft cfs
268.00 .00
268.20 5.37
268.40 15.18
268.60 27.89
268.80 92.93
269.00 60.00
269.20 78.87
269.40 89.70
269.60 91.09
269.80 92.46
270.00 93.81
270.20 95.13
270.40 96.49
270.60 97.74
270.80 99.02
271.00 100.28
271.20 101.52
271.90 102.75
271.60 103.96
271.80 105.17
272.00 106.35
S/N: 621701207003
PondPack Ver. 8.0058
***** COMPOSITE OUTFLOW SUMMARY ****
Notes
------ -- Converge -------------------------
TW El ev Error
ft +/-ft Contributing Structures
------
Free -- -----
Outfall --------------------------
(no Q: RI, BA)
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 RI, BA
Free Outfall RI, BA
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 RIBA
Free Outfall RIBA
The John R> McAdams Company
Time: 5:29 PM Date: 6/28/2007

HMS * Summary of Results for SWMF #7
Project CTX-06070
• Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 29Jun07 1417
Run Name POST - Q100
Basin Model POST [DESIGN] - WC
Met. Model Q100
Control Specs 1-min dT
Computed Results
Peak Inflow 221.80 (cfs) Date/Time of Peak Inflow 16 Feb 07 2004
Peak Outflow 99.607 (cfs) Date/Time of Peak Outflow 16 Feb 07 2014
Total Inflow 5.15 (in) Peak Storage 2.5183(ac-f t)
Total Outflow 5.12 (in) Peak Elevation 270.89 (f t)
•

•
•
HIGHLAND CREEI{
CTX-06070
SWMF #10
_> Stage -Storage Function
ICs= 27t2ti
b= 1.1'98
Zo= ~"_.00
W Elevation ~ Storage
~feet~ ~Cf~ nacre-feet 100-YR
z?Z.oo a ~ o.ooo
_
_
~
272.20~~N~~
4062 ~' .
j 0.093 ~
s ~~.~
_
_
_. ..
._ ~.M....._..µ___
__~_____~_.. _
272:40 - _ 9202 i 0.211 i -.
--272
60 14847~~ 0
341
.
^m .
272.80 '
20847 0.479
273
OQ
27126 0
623
~
.
_t_
t .
.
2
73:20 ~ 33636 ' 0:772
_
.. _._ ~.,__.._ ______~_ .
.2'73.40 4034:5 I ..e_r_..._..
0:926 ~
~__~...
^ ~ 273.60' ~ 47229 _ ~_-
µ
. - .1.084 _
273.8O 54270 1.246
274:0
0 i
61953- ? L.411
_
_
274_.20 r( 68766 ~ i
.,.~{......__-.._~._
_,. 1.579 ~~
...
....
._ µ ~- ~~
.
V...
~...
..
~
274.:40 ( 7620E .
F
,
1.7
49 .
.
.
_
274.60 83747- I 1.923
274:80~~µNµ91399 i ~ 2.098~~- -~- ~µm

275:00 ~ 99150 ~~2.276 _ _
^am
275.20 106995 ~ ~
2.456

275.40 114928 ~
275.60 12294.5
~ 2.63:8 _,
2.82
2 , W_
131043 1F
2_75:80 _
3.00~~
276:0~1392~:18W;i, 3.196 __ ~~
276.20 E
147467 3.
385 ':
_
276:40 F 155987 !~ _
3 576 ~~ .~
~

X76
60 164175 __
3 769 [ _
__
0
000
.
., _~_.__s_..___.____--~--..
..~...~
.________.m.~ .
.
276.80 172629 i 3.963 ;
~ 0.194
~~~
277
00 t I$1-147 ~ 4159
E 0.390
_
_..,__r # ~
277.2_0 189726.
~ _
4.356 _
_
_e
0.587
277:40
1.98364 ~
~ 4.554
~ ~.~_~ . ~ .. 0.785
_ ____~.~.
277.60 ` 207061
~
~ 4.753
F
a 0.985
-_
_.. _._
.__
277.80_:; 215813 i -._
. __
4.954 ._______.._._
l.l8S
~µ 278.00 ~ ~~224620~*~~
; _ _
-5.157 j~ 1.388
u-.~~_~_.._._..~._
.__
27820 '? 233480 i ___~H_.__m
5.360 i ______~~
LS91
27
8:40 ~ 242391 i 5.565 1.796
_
278:60. 251353 ~ _
5.770
_.. s _ 2.001 _..
_ _ ______
278.80 2_60363 , 5.977_
. _ 2.208
~.
279:00 .269422 6.185
~ 2:416
_ ...v..._._._.___.. ~.__
279.20 i 278527 i ___ _-------_-
--._
94
6.3 _______ _.._
2.625

279.40 287677 _~ _
_
6:604 ~ v _
2.835
2_79.60 296872
~ 6.81 S t . 3.046
279:0 ~
306111 7:027 3
2
58
280.00 W315392~ ,
7.240 ~ _
_
3.471
J. ALDRIDGE, EI
5/3/2007

•
Type.... Composite Rating Curve
Name.... SWMF #10 - Q100
Page 1.09
File.... X:\Projects\CTX\CTX-0607-0\Storm\Design Files\SWMF DESIGN.PPW
Title... Project Date: 2/1672007
Project Engineer: J. ALDRIDGE, EI
Project Title: HIGHLAND CREEK
Project Comments:
**** COMPOSITE OIITFLOW SOMMARY ****
•
C7
WS Elev, Total Q Notes
-------- -------- ------ -- Con.verge ------------
Elev. Q TW El ev Error
ft cfs ft +/-ft
---- Contributing Structures
--------------------------
--------
276.60 -------
.00 ------
Free -- -
O"utfall (no Q: RI, BA)
276.80 5.37 Free Outfall RI, BA
277.00 15.18 Free Outfall RI, BA
277.20 27.89 Free Outfall RIBA
277.40 42.93 Free Outfall RIBA
277.60 60.00 Free Outfall RI, BA
277.80 78.87 Free Outfall RL,BA
278.0.0 93.84 Free Outfall RS,BA
278.20 95.18 Free OuEfa11 RI, BA
278.40 96.49 Free Outfall RI, BA
278.60 97.78. Free Outfall RI, BA
278.8:0 99.05 Free Outfall RIBA
279.00 100.31 Free Outfall RIBA
279.20 101.55 Free Outfall RL,BA
279.40 102.78 Free Outfall RI, BA
279.60. 104.00 Free Outfal.l RIBA
279.80 105.20 Free Outfall RI, BA
280.00 .106.38 Free Outfall RI,BA_
S/N'. 621701207003 The John. R. McAdams Company
PondPack Ver. 8.0058 Time.: 2:51 PM Date: 5/2/2007

FiMS * Summary of Results for SFTMF #10
Project CTX-06070
Start of Run 16Feb07 0800
End of Run 17Feb07 0800
Execution Time 14Jun07 1711
Run Name POST - Q100
Basin Model POST [DESIGN] - WC
Met. Model Q100
Control Specs 1-min dT
Computed Results
Peak Inflow 206.67 (cfs)
Peak Outflow 99.997 (efs)
Total Inflow 5.73 (in)
Total Outflow 5.70 (in)
Date/Time of Peak inflow 16 Feb 07 2004
Date/Time of Peak Outflow 16 Feb 07 2013
Peak Storage 2.3643 (ac-ft)
Peak Elevation 278.95(ft)
•
•

•
TN-LOADING CALCULATIONS
PHASES 1, 2, ~ 4

C~
HIGHLAND CREEK
CTX-06070

1.- --__
LEGEND
SINGLE-FAMILY - 94.75 ACRES I%~ll/T>~
MULTI-FAMILY = 49.52 ACRES r l
STREAM BUFFER / COMMON RW AREA = 31.78 ACRES r- ~
TOTAL TN-AREA CPHASE 1, 2, AND 4) = 176.05 ACRES
~<
~\
~,~ .,~ .

~' I
.i ~.,=y
GRAPHIC SCALE
600 0 300 600 1200
1 inch = 600 ft.
Q
~~
w o
N } U ~
F4 1-I W Z I
z ~ x~
~ ya
O Z ~
l 0.
Q, Z .W.1 N
Z U
W ~ 5 < ,(J o
~,~,y O a x °o °o
hl~ ~ H N
E-' U w ~x~
W w O c~
pad z ~ w
~ ~ o rn
Z w
W CL 0. ~
W ~~_l
~"'1
O N
.-~
~U~
~~
Q~
Oo
~~
C'3 ~
~~o
~w~
~~z
McADAMS

,,~ ,
,~
~~_

HIGHLAND CREEK POST DEVELOPMENT NITROGEN EXPORT CALCULATIONS J. ALDRIDGE, EI
CTX-06070 6/15/2007
• I. POST DEVELOPMENT
__> TN Load Area - To SWMF #
To
Assume
Total
Watershed Breakdown
3~
tal Number of Phase 1 Residential Lots =
d Impervious Area Per Residential Lot =
Impervious Area from Residential Lots =
Additional Measured Impervious Area =
0
3600
0.00
3.75
lots
square feet
acres
acres
Contributing Area Area [acres)
Onsite im ervious 3.75

~. Onsite open _
2.28 _
Onsite wooded 0.00
Onsite and 0.44
C,
Total area = 6.47
__> TN Load Area - To SWMF #4
Total Number of Phase 1 Residential Lots =
Assumed Imperi~ious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impen~ious Area =
Watershed Breakdown
Contributing Area Area [acres)
Onsite impervious 11.99

Onsite open _
~ 9.10 ~ ~~
Onsite wooded 0.00

Onsite and _
____
_ 0.46
Total area = 21.55
__> TN Load Area - To SWMF #5
Total Number of Phase I Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total /mpervious Area from Residential Lots =
Additional Measured Impen~ious Area =
Watershed Breakdown
Contributing Area ~ Area [acres)
Onsite impervious 7.60
Onsite o en 7.27
Onsite wooded
_ _ 0.00
Onsite nd 0.33
Total area = 15.20
acres
27.5 lots
3600 square feet
2.27 acres
9.72 acres
acres
60
3600
4.96
2.64
acres
lots
square feet
acres
acres
•

HIGHLAND CREEK POST DEVELOPMENT NITROGEN EXPORT CALCULATIONS
CTX-06070
• __> TN Load Area - To SWMF #6
Total Number of Phase 1 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impervious Area =
Watershed Breakdown
Contributing Area Area nacres[
Onsite imEervious ~ 6.21
~
Onsite o en 6.67
Onsite wooded 0.00
Onsite pond { 0.32
r~
Total area = 13.20
_> TN Load Area - To SWMF #I
Tota[ Number of Phase 1 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Number of Phase 2 and 4 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impervious Area =
Watershed Breakdown
37.5 lots
3600 square feet
3.10 acres
3.11 acres
acres
1.5 lots
3600 square feet
93 lots
4000 square feet
8.66 acres
2.95 acres
Contributing Area Area [acres)
Onsite impervious 11.61 _ _ ___
_
Onsite open ~ 10.63
_~
Onsite wooded 0.00
~~~
Onsite and 0.56
Total area = 22.80
__> TN Load Area - To SWMF #2
Total Number of Phase 1 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Number of Phase 2 and 4 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impervious Area =
Watershed Breakdown
Contributing Area Area [acres[
Onsite im ervious 6.71
Onsite omen 4.52
Onsite wooded 0.00
~~
Onsite and 0.33
acres
1 lots
3600 square feet
0 lots
4000 square feet
0.08 acres
6.63 acres
Total area = 11.56 acres
J. ALDRIDGE, EI
6/15/2007
•

HIGHLAND CREEK POST DEVELOPMENT NITROGEN EXPORT CALCULATIONS
CTX-06070
__> TN Load Area - To SWMF #7
Total Number of Phase I Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Number of Phase 2 and 4 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impervious Area =
Watershed Breakdown
Contributing Area Area, nacres]
Onsite im ervious 9.88
Onsite o en 7.93
Onsite wooded 0.00
_
Onsite and 0.00
Total area = 17.81
_> TN Load Area - To SWMF #10
Total Number of Phase /Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Number of Phase 2 and 4 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total /mpervious Area from Residential Lots =
Additional Measured Impervious Area =
• Watershed Breakdown
Contributing Area Area [acres]
Onsite impervious 12.97
Onsite o en _11.50
Onsite wooded 0.00
Onsite and 0.65
0 lots
3600 square feet
9.5 lots
4000 square feet
0.87 acres
9.01 acres
acres
0 lots
3600 square feet
95 lots
4000 square feet
8.72 acres
4.25 acres
Total area = 25.12
_> TN Load Area -Phases 1, 2, & 4 Bypass
Total Number of Phase 1 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Number of Phase 2 and 4 Residential Lots =
Assumed Impervious Area Per Residential Lot =
Total Impervious Area from Residential Lots =
Additional Measured Impervious Area =
Watershed Breakdown
acres
30.5 lots
3600 square feet
18.5 lots
4000 square feet
4.22 acres
3.87 acres
Contributing Area Area nacres]
Onsite im ervious 8.09
Onsite o en 20.08
Onsite wooded 13.00
_.___._ Onsite and 1.17
• Total area = 42.34 acres
J. ALDRIDGE, EI
6/ 15/2007

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SUBBASIN #1 ANAL YSIS
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HIGHLAND CREEK
CTX-06070

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~
® PROJECT NO. CTX-OFO7O

FILENAME:
HIGHLAND CREEK THE JOHN R. McADAMS
COMPANY, INC.

~ SB~ PRE
ENGINEERS/PLANNERS/SURVEYORS
p SCALE:
~
, SUBBASIN 1 ANALYSIS NC
RESEARCH TRIANGLE PARK
~
_ ~ oo T HYDROLOGY ,
P.o. sox laoos zIP 27709-4005
PRE-DEVELOPMEN (919) 381-s000
~ DATE: O5-~ 7-ZOO7

HIGHLAND CREEx HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre Development -Subbasin 1 5/17/2007
1. tiC~ CL7RVE N[711BEI2S
• Cover Condition SCS CN Comments
Im rvious 98
~._.._.. ~Pen..._.__..._._.. _ .____..__61__.._..__. .___._Assume good condition
Wooded 55 Assume good condition
II. PKb; DFVFL[1P31tiV'T
_> Subbasin #1- Onsite
A. Watershed Breakdown
•
Contributing Area SCS CN Area JacresJ Comments
Onsite im rvious 98 0.58

_.__..___Onsite open_._._..._.
Onsite wooded
..__....__._._61 _.___.._..
55
___... 2.53__ _
0.14 _
__ Assume good condition___.
Assume ood condition
Onsitepond_ __
_ Offsite im rvious 100
98 0.00
0.00 -
__Offsite_open
Offsite wooded _ 61
55 _ 0.00
0.00 Assume good condition
Assume ood condition
Offsite nd 100 0.00 -
Total area = 3.25 acres
0.0051 sq.mi.
Composite SCS CN = 67
Impervious = 17.8%
B. Time of Concentration Information
Segment l: Overland Flow Segment 2: Concentrated Flow
Length = ] 00 ft Length = 421 ft
Height = 3 ft Height = 20 ft
Slope = 0.0300 ft/ft Slope = 0.0475 ft/ft
Manning's n = 0.24 Dense grasses Paved ? = No
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) Velocity = 3.53 ft/sec
Segneent Time = ll.d-t minutes Segment Time = ?.Ot! minutes
Time of Concentration = 13.44 minutes
SCS Lag Time = 8.06 minutes (SCS Lag = 0.6* Tc)
= 0.1344 hours
Time Increment = 2.34 minutes (= 0.29*SCS Lag)
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Pre Development -Subbasin / 5/17/2007
• _> Subbasin #I - Ofjsite
A. Watershed Breakdown
Contributing Area 5C5 CN Area JacresJ Comments
Onsite im rvious 98 0.00
_ Onsite open _
m _ 6_I__
___ _0.00
____
mm Assume good condition__
Onsite wooded 55 0.00 Assume ood condition
_Onsite po°_d....._..... .___100.____ 0.00 _
-

Offsite im rvious
98
0.91 ..
_ ~e_______
Offsite~n 61 _
~ 4.98
_ Assumesood condition
Offsite wooded 55 0.36 Assume ood condition
Offsite nd 100 0.00 -
Total area = 6.25 acres
0.0098 sq.mi.
Composite SCS CN = 66
Impervious = 14.6%
B. Time of Concentration Information
Segment 1: Overland Flow Segment 2: Overland Flow
Length = 52 ft Length = 48 ft
Height = 2 ft Height = 1 ft
Slope = 0.0385 tuft Slope = 0.0208 ft/ft
Manning's n = 0.40 Woods-Dense underbrush Manning's n = 0.24 Dense grasses
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) P (2-year/24-hour) = 3.6 inches (Raleigh, NC)
Segment Time = ~1.2J minutes Segment Time = '.ifi minutes
Segment 3: Concentrated Flow Segment 4: Chan nel Flow
Length = 324 ft Length = 267 ft
Height = 8 ft Height = 5 ft
Slope = 0.0247
• ft/ft Slope = 0.0187 ft/ft
Paved ? = No Manning's n = 0.045 Natural Channel
Velocity = 2.:+4 ft/sec Flow Area = 9.00 sf (Assume 2' x 2' Channel)
Wetted Perimeter = 9.00 ft (Assume 2' x 2' Channel)
Segment Time = 2.13 minutes Channel Velocity = 4.?3 ft/sec
Segment Time = 0.98 minutes
Time of Concentration = 19.71 minutes
SCS Lag Time = 11.82 minutes (SCSLag = 0.6* Tc)
= 0.1971 hours
Time Increment = 3.43 minutes (= 0.29*SCS Lag)
•

•
HEC-HMS Project: CTX-06070
~._
•`_Ff` Sub 1 C7nsite
Sub 1 Uff~ite
Sub 1 to 18" RCP
Basin Model: SUB 1 PRE
•

HMS * Summary of Results
Project CT%-060 70 Run Name SUB 1 PRE Q2
• Start of Run 16Feb07 0800 Basin Model SUB 1 PRE
Snd of Run 17Feb07 0800 Met. Model Q2
Execution Time 17May07 1605 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
8lement Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 1 Onsite
Sub 1 Off site
Sub 1 to 18" RCP
•
3.5417 16 Feb 07 2011 0.24551 0.005
5.2642 16 Feb 07 2016 0.44413 0.010
8.4572 16 Feb 07 2014 0.68964 0.015
•

HMS * Summary of Results
Project CT%-06070 Run Name SUB 1 PRE Q10
• Start of Run 16Feb07 0800 Basin Model SUB 1 PRE
End of Run 17Feb07 0800 Met. Model Q10
Execution Time 17May07 1605 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 1 Onsite
Sub 1 Offsite
Sub 1 to 18" RCP
•
7.6929 16 Feb 07 2010 0.56144 0.005
12.091 16 Feb 07 2015 1.0351 0.010
19.172 16 Feb 07 2013 1.5965 0.015
•

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PROJECT No. CTX-06070
HIGHLAND CREEK
~
THE JOHN R. McADAM
INC
COMPANY
EaENAME: see POST .
,
ENGINEERS/PLANNERS/SURVEYORS
y
d sCA~E:
"
. SUBBASIN 1 ANALYSIS
~ ~
_ ~ 00 RESEARCH TRIANGLE PARK, NC
DATE:
05-17-2007 POST-DEVELOPMENT HYDROLOGY P.o. sox laoos ztP z7voa-coos
(sls) 981-sooo ~

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, El
CTX-06070 Post Development - Subbasin I 5/17/2007
•
I. SCS CURVE'NU1ViBE)ZS
Cover Condition SCS CN Comments
Im rvious 98
Open _
~ 61 _Assum_e good condition
~
Wooded 55 Assume ood condition
IL YOtiT DLVELOP~ti1F:A''1~
_> Subbasin #1- Onsite
A. Watershed Breakdown

Phase
# Lots
Imp/Lot ~sQ Lot
Impervious
acres Other*
Impervious
acres Total
Impervious
acres
1
1 B 0
0 3600
3600 0.00
0.00 0.00
0.00 0.00
0.00
2 0.5 4000 0.05 0.48 0.53
3 7.5 4000 0.69 0.00 0.69
4 0 4000 0.00 0.00 0.00
'^t~urer tmpernor~s mc[uaes tmpervrons /rom t owmromes, vreenway i raus, ana nrgnL-o7-rvay
Contributing Area SCS CN Area ~acresJ Comments
Onsite impervious
Onsite o n 98
61 1.21
1.55 -
Assume ood condition
Onsite wooded
~Onsite~ond~- __ 55
~ 100 ~ _ 0.00_
0.00 _^Assumepood condition _
Offsite impervious
Offsite o en 98
6l 0.00
0.00 -
Assume ood condition
Offsite_wooded _ 55
_
~~ __0.00 Assume~oodcondition _
Offsite and 100 0.00 -
Total area = 2.76 acres
0.0043 sq.mi.
Composite SCS CN = 77
Impervious = 43.9%
B. Time of Concentration Information
7Tie post development time ofconcentration is assumed to be S 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)
•

HIGHLAND CREEK HYDROLOGIC CALCULATIONS J. ALDRIDGE, EI
CTX-06070 Post Development -Subbasin 1 5/17/2007
• -> Subbasin #1 - Offsite
A. Watershed Breakdown
Contributing Area SCS CN Area [acres) Comments
Onsite im ervious 98 0.00
__ Onsite open ~_ 61 _ 0.00
_ Assume food condition
Onsite wooded 55 0.00 Assume ood condition
Onsite pond.___..__.
Offsite im rvious ..___........100.._. __.__
98 ._._ x:00 ..__.~
0.98 ._~__. __. _._ _ _'_._. _.
-
_.._..__Offsite open _
Offsite wooded _._-.____61__._ _.
55 4.91 _
0.36 ___ Assume good condition___
Assume good condition
____
~~
Offsite nd 100 0.00 -
•
Total area = 6.25 acres
0.0098 sq.mi.
Composite SCS CN = 66
Impervious = 15.7%
B. Time of Concentration Information
Segment l: Overland Flow Segment 2: Overland Flow
Length = 23 ft Length = 77
Height = 0.5 ft Height = 3
Slope = 0.0217 ft/ft Slope = 0.0390
Manning's n = 0.40 Woods-Dense underbrush Manning's n = 0.24
P (2-year/24-hour) = 3.6 inches (Raleigh, NC) P (2-year/24-hour) = 3.6
Segment Time = 6.l)J minutes Segment Time = 4.3b
Segment 3: Concentrated Flow Segment 4: Chan nel Flow
Length = 313 ft Leng[h = 267
Height = 8 ft Height = 5
Slope = 0.0256 ft/ft Slope = 0.0187
Paved ? = No Manning's n = 0.045
Velocity = 2.iS ft/sec Flow Area = 9.00
Wetted Perimeter = 9.00
Segment Time = ?.0? minutes Channel Velocity = 453
Segment Time = t1.9R
ft
ft
ft/ft
Dense grasses
inches (Raleigh, NC)
minutes
ft
ft
ft/ft
Natural Channel
sf (Assume 2' x 2' Channel)
ft (Assume 2' x 2' Channel)
ft/sec
minutes
Time of Concentration = 17.41 minutes
SCS Lag Time = 10.44 minutes (SCS Lag = 0.6* Tc)
= 0.1741 hours
Time Increment = 3.03 minutes (= 0 29*SCS Lag)
•

HEC-HMS Project: CTX-06070 Basin Model: SUB 1 POST

Sub ? C7#fsite
•
;P
•

HMS * Summary of Results
Project CTS-06070 Run Name SUB 1 POST Q2
• Start of Run 16Feb07 0800 Basin Model SUB 1 POST
End of Run 17Feb07 0800 Met. Model Q2 ,
Execution Time 17May07 1354 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 1 Onsite
Sub 1 Offsite
Sub 1 tO 18" RCP
•
7.2806 16 Feb 07 2005 0.34450 0.004
5.2642 16 Feb 07 2016 0.44413 0.010
9.3436 16 Feb 07 2006 0.78863 0.014
•

HMS * Summary of Results
Project CTS-06070 Run Name SUB 1 POST Q10
• Start of Run 16Feb07 0800 Basin Model SUB 1 POST
End of Run 17Feb07 0800 Met. Model Q10
Execution Time 17May07 1355 Control Specs 1-min dT
Hydrologic Discharge Time of Volume Drainage
Element Peak Peak (ac Area
(cfs) ft) (sq mi)
Sub 1 Onsite 12.113 16 Feb 07 2005 0.67393 0.004
Sub 1 Offsite 12.091 16 Feb 07 2015 1.0351 0.010
Sub 1 to 18" RCP 18.840 16 Feb 07 2006 1.7090 0.014
•
u

Culvert Calculator Report
18" RCP Pre Q2
~Ive For: Headwater Elevation
Culvert Summary
Allowable HW Elevation 0.00 ft Headwater Depth/ Height 1.30
Computed Headwater Elevation 286.11 ft Discharge 8.46 cfs
Inlet Control HW Elev 286.06 ft Tailwater Elevation 0.00 ft
Outlet Control HW Elev 286.11 ft Control Type Outlet Control

Grades
Upstream Invert 284.16 ft Downstream Invert 283.10 ft
Length 52.00 ft Constructed Slope 2.04

Hydraulic Profile
Profile S2 Depth, Downstream 0.83 ft
Slope Type Steep Normal Depth 0.81 ft
Flow Regime Supercritical Critical Depth 1.13 ft
Velocity Downstream 8.45 ft/s Critical Slope 0.78

Section
Section Shape Circular Mannings Coefficient 0.013
Section Material Concrete Span 1.50 ft
Section Size 18 inch Rise 1.50 ft
Number Sections 1

utlet Control Properties
Outlet Control HW Elev 286.11 ft Upstream Velocity Head 0.55 ft
Ke 0.50 Entrance Loss 0.27 ft

Inlet Control Properties
Inlet Control HW Elev 286.06 ft Flow Control Transition
Inlet Type Square edge w/headwall Area Full 1.8 ftZ
K 0.00980 HDS 5 Chart 1
M 2.00000 HDS 5 Scale 1
C 0.03980 Equation Form 1
~' 0.67000
•
Project Title: Highland Creek Project Engineer: Jon Aldridge
x:\...\ctx-06070\storm\design files\ligon mi.cvm The John R. McAdams Company CulvertMaster v1.0
06/07/07 03:01:36 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA [phone] Page 1 of 1

Culvert Calculator Report
18" RCP Pre Q10
~Ive For: Headwater Elevation
Culvert Summary
Allowable HW Elevation 0.00 ft
Computed Headwater Elevation 289.83 ft
Inlet Control HW Elev 289.83 ft
Outlet Control HW Elev 289.06 ft Headwater Depth/ Height
Discharge
Tailwater Elevation
Control Type 3.78
19.17 cfs
0.00 ft
Inlet Control

Grades
Upstream Invert
Length 284.16 ft
52.00 ft Downstream Invert
Constructed Slope 283.10 ft
2.04

Hydraulic Profile
Profile
Slope Type
Flow Regime
Velocity Downstream CompositeM2Pressure
Mild
Subcritical
10.92 fUs Depth, Downstream
Normal Depth
Critical Depth
Critical Slope 1.46 ft
N/A ft
1.46 ft
2.95

Section
Section Shape
Section Material
Section Size
Number Sections Circular
Concrete
18 inch
1 Mannings Coefficient
Span
Rise 0.013
1.50 ft
1.50 ft

~utlet Control Properties
Outlet Control HW Elev
Ke 289.06 ft
0.50 Upstream Velocity Head
Entrance Loss 1.83 ft
0.91 ft

Inlet Control Properties
Inlet Control HW Elev
Inlet Type
K
M
C
~' 289.83 ft
Square edge w/headwall
0.00980
2.00000
0.03980
0.67000 Flow Control
Area Full
HDS 5 Chart
HDS 5 Scale
Equation Form Submerged
1.8 ft2
1
1
1
•
Project Title: Highland Creek Project Engineer: Jon Aldridge
x:\...\ctx-06070\storm\design files\ligon mi.cvm The John R. McAdams Company CulvertMaster v1.0
06/07/07 03:02:20 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA [phone] Page 1 of 1

Culvert Calculator Report
18" RCP Post Q2
~Ive For: Headwater Elevation
Culvert Summary
Allowable HW Elevation 0.00 ft Headwater Depth/ Height 1.40
Computed Headwater Elevation 286.26 ft Discharge 9.34 cfs
Inlet Control HW Elev 286.26 ft Tailwater Elevation 0.00 ft
Outlet Control HW Elev 286.25 ft Control Type Inlet Control

Grades
Upstream Invert 284.16 ft Downstream Invert 283.10 ft
Length 52.00 ft Constructed Slope 2.04

Hydraulic Profile
Profile S2 Depth, Downstream 0.88 ft
Slope Type Steep Normal Depth 0.86 ft
Flow Regime Supercritical Critical Depth 1.18 ft
Velocity Downstream 8.64 ft/s Critical Slope 0.85

Section
Section Shape Circular Mannings Coefficient 0.013
Section Material Concrete Span 1.50 ft
Section Size 18 inch Rise 1.50 ft
Number Sections 1

utlet Control Properties
Outlet Control HW Elev 286.25 ft Upstream Velocity Head 0.61 ft
Ke 0.50 Entrance Loss 0.30 ft

Inlet Control Properties
Inlet Control HW Elev 286.26 ft Flow Control Submerged
Inlek Type Square edge w/headwall Area Full 1.8 ftz
K 0.00980 HDS 5 Chart 1
M 2.00000 HDS 5 Scale 1
C 0.03980 Equation Form 1
~' 0.67000
•
Project Title: Highland Creek Project Engineer: Jon Aldridge
x:\...\ctx-06070\storm\design files\ligon mi.cvm The John R. McAdams Company CulvertMaster v1.0
06/07/07 03:03:31 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA [phone] Page 1 of 1

Culvert Calculator Report
18" RCP Post Q10
~Ive For: Headwater Elevation
Culvert Summary
Allowable HW Elevation 0.00 ft Headwater Depth/ Height 3.68
Computed Headwater Elevation 289.67 ft Discharge 18.84 cfs
Inlet Control HW Elev 289.67 ft Tailwater Elevation 0.00 ft
Outlet Control HW Elev 288.91 ft Control Type Inlet Control

Grades
Upstream Invert 284.16 ft Downstream Invert 283.10 ft
Length 52.00 ft Constructed Slope 2.04

Hydraulic Profile
Profile Composite M2Pressure Depth, Downstream 1.46 ft
Slope Type Mild Normal Depth N!A ft
Flow Regime Subcritical Critical Depth 1.46 ft
Velocity Downstream 10.74 ft/s Critical Slope 2.84

Section
Section Shape Circular Mannings Coefficient 0.013
Section Material Concrete Span 1.50 ft
Section Size 18 inch Rise 1.50 ft
Number Sections 1

~utlet Control Properties
Outlet Control HW Elev 288.91 ft Upstream Velocity Head 1.77 ft
Ke 0.50 Entrance Loss 0.88 ft

Inlet Control Properties
Inlet Control HW Elev 289.67 ft Flow Control Submerged
Inlet Type Square edge w/headwall Area Full 1.8 ftZ
K 0.00980 HDS 5 Chart 1
M 2.00000 HDS 5 Scale 1
C 0.03980 Equation Form 1
~' 0.67000
•
Project Title: Highland Creek Project Engineer: Jon Aldridge
x:\...\ctx-06070\storm\design files\ligon mi.cvm The John R. McAdams Company CulvertMaster v1.0
06/07/07 03:04:04 PM ©Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA [phone] Page 1 of 1