20140800 Ver 1_20140523 Stormwater Impact Analysis_20140729

STORMWATER IMPACT ANALYSIS & PRELIMINARY
DESIGN OF STORMWATER MANAGEMENT FACILITIES
THE EDGE
RAV -13000
CHAPEL HILL, NC
DATE: JANUARY 2014
REVISED: MAY 2014
PREPARED FOR:
NORTHWOOD RAVIN
4819 EMPEROR BOULEVARD, SUITE 320
DURHAM, NC 27703
McADAMS
Raleigh /Durham ■ 2905 Meridian Parkway ■ Durham, NC 27713
Charlotte ■ 11301 Carmel Commons Blvd ■ Suite 111 ■ Charlotte, NC 28226
McAdamsCo.com
Designing Tomorrow's Infrastructure & Communities

THE EDGE
CHAPEL HILL, NORTH CAROLINA
STORMWATER IMPACT ANALYSIS &
PRELIMINARY DESIGN OF STORMWATER
MANAGEMENT FACILITIES
PROJECT NUMBER:
DESIGNED BY:
DATE:
REVISED:
'J
RAV -13000
D. AMOS CLARK, PE
JON ALDRIDGE, PE
JAMES EASON, EI
JANUARY 2014
MAY 2014
MCADATAS
2905 MERIDIAN PARKWAY
DURHAM, NORTH CAROLINA 27713
NC Lic. # C -0293

the EDGE
Stormwater Impact Analysis and Preliminary Design of
Stormwater Management Facilities
General Description & Background
Located on Eubanks Road, just west of its intersection with Martin Luther King Jr. Boulevard on
the north edge of Chapel Hill, N.C., is the site for the proposed development, the Edge. This
proposed site will be a mixed use development containing commercial and residential
development with associated streets, parking areas, utility improvements, and stormwater
management improvements. At build -out, the Edge development is anticipated to be a 54 acre
mixed use development containing 430 multi- family units, a hotel, 126,000 square feet of retail
space, and 96,000 square feet of office space.
The proposed development is located within the Cape Fear River basin, inside of the Town of
Chapel Hill Watershed Protection District, with stormwater runoff from the proposed
development draining directly into Old Field Creek. According to the N.C. Division of Water
Quality BasinWide Information Management System (BIMS), Old Field Creek (Stream Index
#16- 41 -1 -7) is classified as WS -V;NSW at this location. Development on this site is subject to
requirements set forth in the Chapel Hill Land Use Management Ordinance.
These are as follows:
5.4.6. General Performance Criteria for Stormwater Management
The following are required stormwater management performance criteria:
(a) Stormwater treatment shall be designed to achieve average annual eighty -five (85) percent total
suspended solids (TSS) removal and must apply to the volume of post- development runoff
resulting from the first one -inch of precipitation. Alternative treatment methods to achieve
eighty -five (85) percent average annual TSS removal may be acceptable. The eighty -five (85)
percent requirement applies to eighty -five (85) percent of the additional suspended solids that
are the result of the new development. (Ord. No. 2004 -02- 2310 -2)
(b) The stormwater runoff volume leaving the site post- development shall not exceed the stormwater
runoff volume leaving the site pre - development (existing conditions) for the local 2 -year
frequency, 24 -hour duration storm event for all development except single-family and two-family
dwellings on lots existing as of January 27, 2003, or on lots pursuant to a preliminary plat that
was approved by the town council prior to January 27, 2003. This may be achieved by
hydrologic abstraction, recycling and /or reuse, or any other accepted scientific method.
(c) The stormwater runoff rate leaving the site post- development shall not exceed the stormwater
runoff rate leaving the site pre - development (existing conditions) for the local 1 -year, 2 -year,
and 25 -year 24 -hour storm events.
(d) Land disturbance within the stream channel of any ephemeral stream shall be minimized, and
prohibited unless explicitly authorized by issuance of a zoning compliance permit after
demonstration of the necessity for the disturbance.

5.19.7. Design and Performance Standards for Stormwater Management
(a) Nitrogen and phosphorus loading
(1) Stormwater systems shall be designed to control and treat the runoff generated from all
surfaces by one inch of rainfall. The treatment volume shall be drawn down pursuant to
standards specific to each practice as provided in the State Design Manual.
(2) The nitrogen load contributed by the proposed development shall not exceed 2.2 pounds
per acre per year.
(3) The phosphorus load contributed by the proposed development shall not exceed 0.82
pound per acre per year.
(4) Notwithstanding 15A NCAC 2B. 104(q), redevelopment subject to this Section that would
replace or expand existing structures or improvements and would result in a net increase
in built -upon area shall have the option of either meeting the loading standards identified
in subsections 5.19.7(a)(2) and (3) above, or achieve 35 percent and S percent reduction
for nitrogen and phosphorus, respectively, compared to the existing development.
(5) The applicant shall determine the need for and shall design structural best management
practices to meet these loading rate targets by using the approved accounting tool.
(b) Nitrogen and phosphorus standards are supplemental. The nitrogen and phosphorus loading
standards in this Section are supplemental to, not replacements for, stormwater standards
otherwise required by Section 5.4 of the town's Land Use Management Ordinance.
(c) Partial offset of nutrient control requirements. Before using offsite offset options, a development
subject to this Section shall attain a maximum nitrogen loading rate onsite of six pounds per acre
per year for single-family, single-family with accessory apartment, and duplex residential
development and ten pounds per acre per year for other development, including multi family
residential, commercial and industrial and shall meet all requirements for structural best
management practices otherwise imposed by this Section. A person subject to this Section may
achieve the additional reductions in nitrogen and phosphorus loadings by making offset
payments to the North Carolina Ecosystem Enhancement Program (Program) contingent upon
acceptance of payments by that Program. An applicant may propose other offset measures,
including providing his or her own offsite offset or utilizing a private seller. All offset measures
permitted by this ordinance shall meet the requirements of 15A NCAC 02B.0273 (2) through (4)
and 15A NCAC 02B. 0240.
(d) Structural best management practices that are designed, constructed, and maintained in
accordance with the criteria and specifications in the design manuals and the approved
accounting tool will be presumed to meet the minimum water quality performance standards of
this Section.
To address the requirements listed above for the Edge, multiple stormwater management
facilities with level spreaders are proposed for use on this site. The proposed stormwater
management facilities are designed in accordance with the N.C. Stormwater Best Management
Practices manual (NCDENR).
This report contains calculations detailing the expected stormwater impacts as a result of the
proposed development, along with the preliminary design calculations for the proposed
2

stormwater management facilities that will be used to mitigate the impacts. Please refer to the
appropriate sections of this report for additional information.
Calculation Methodolo
➢ Rainfall data for the Chapel Hill, NC region is from Town of Chapel Hill Design Manual.
The 1- year /24 -hour rainfall depth is 2.98 inches, the 2- year /24 -hour rainfall depth is 3.60
inches, the 25- Year /24 -hour rainfall depth is 6.41 inches, and the 100 - year /24 -hour rainfall
depth is 8.00 inches. All of these storms were modeled within PondPack assuming a center
weighted storm computation based on the complied results. Please reference the precipitation
information section within this report for additional information.
➢ Using maps contained within the Orange County Soil Survey, the on -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 #2 consists of approximately 74% HSG `B' soils and 26% 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 = (74% x 61) + (26% x 80) = 66
➢ A composite SCS Curve Number was calculated for both the pre- and post - development
condition for each subbasin using SCS curve numbers and land cover conditions. Land cover
conditions for the pre- development condition were taken from a combination of field survey
information and Town of Chapel Hill GIS. Land cover conditions for the post - development
condition were taken from the proposed development plan.
➢ The time of concentration was calculated using SCS TR -55 (Segmental Approach, 1986).
The Tc flow path was divided into three segments: overland flow, concentrated flow, and
channel flow. The travel time was then computed for each segment, from which the overall
time of concentration was determined by taking the sum of each segmental time.
➢ The post - development time of concentration to the proposed stormwater management
facilities was assumed to be 5 minutes.
➢ PondPack, Version V8i, by Haestad Methods, was used in determining the pre- & post -
development peak flow rates for the 1 -, 2 -, 25 -, and 100 -year storm events, as well as routing
calculations for the proposed stormwater management facilities. This software was also used
to generate the stage- discharge rating curve for the proposed stormwater management
facilities.
➢ Water quality sizing calculations for the proposed stormwater management facilities were
performed in accordance with the N.C. Stormwater Best Management Practices manual
(NCDENR July 2007). The facility surface areas were sized using the runoff volume
computed using the Simple Method. 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. An additional storage volume was calculated for the difference between the pre -
development and post - development discharge for the 2- year- 24hour storm.
➢ Using the SCS Curve Number Method and composite curve numbers for the pre -
development and post - development onsite area only conditions, run -off volumes were
calculated for the 2 -year / 24 -hour rainfall. The calculated difference in the pre- and post -
development run -off volumes is captured and stored in the facilities and released slowly over
a 2 -5 day period using a low flow orifice.
➢ 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.
➢ TN -Export and TP -Export calculations were computed using the Jordan Lake Accounting
Tool prepared by NC State University for the NC Division of Water Quality.
Discussion of Results
Peak Runoff Control Requirements
The proposed project will result in a significant increase in peak flow rates. To mitigate this
impact, the proposed facilities have been sized such that post - development peak flow rates are no
greater than pre - development levels in the 1 -, 2 -, and 25 -year storm events.
Pollutant and Nutrient Control Requirements
The stormwater facilities onsite are designed such that they achieve 90% TSS. Furthermore, each
facility is designed with a level spreader / vegetated filter system to appropriately discharge the
1" water quality storm safely into the buffers onsite.
Calculations are provided detailing the loading rates resulting from the proposed development.
The anticipated development results in a nitrogen and phosphorous loading rate higher than that
allowed; and therefore, an offset payment to a private mitigation bank and /or NCEEP is required.
Conclusion
If the development on this tract is built as proposed within this report then the requirements set
forth in the Town of Chapel Hill 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:
M

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.

1
SUMMARY OF RESULTS
2
MISCELLANEOUS SITE INFORMATION
3
WATERSHED SOILS INFORMATION
4
PRECIPITATION DATA
5
PRE - DEVELOPMENT HYDROLOGIC
CALCULATIONS
6
POST - DEVELOPMENT HYDROLOGIC
CALCULATIONS
7
STORMWATER MANAGEMENT
`1'
FACILITY DESIGN CALCULATIONS
8
STORMWATER MANAGEMENT
FACILITY `2' DESIGN CALCULATIONS
9
STORMWATER MANAGEMENT
FACILITY `3' DESIGN CALCULATIONS
i O
STORMWATER MANAGEMENT
FACILITY `4' DESIGN CALCULATIONS
11
NUTRIENT LOADING CALCULATIONS

SUMMARY OF RESULTS
THE -EDGE
RAV -13000

THE EDGE SUMMARY Or RESULTS
RAV -13000
= => RELEASE RATE MANAGEMENT RESULTS
POA #I
Return Period
x Pre - Development
Post
Development
1 -Year
% Increase
[cfs]
1 %]
-8.9%
[cfs]
39.29
_[ %] _
I -Year
27.21
25 Year
20.57
- 24.4%
m�
2 -Year
_
50.17
_
106.80
34.75
84.05
-30.7%
25 -Year
176.66
�
- 137.22 -�
- 22.3%
POA #2
Return Period
Pre - Development
Post - Development
Post-
-increase
1 -Year
[cfs] a.
21.37
19.47
1 %]
-8.9%
2 -Year
39.29
15.40
j 16.2%
_
25 Year
135.27
_32.93
124.39_
8.0%
POA #3
'— Return Period
—7T-Ti re - Development
Post - Development -%
Increase
[cfs]
[cfs]
1%]
I -Year
17.57
15.40
-12.4%
-Year
g 32.01
25.52
- 2_0.3%
_2
25 -Year
_
106.80
84.05
_21.3 %_____.__
POA #4
Return Period Pre - Development Post - Development % Increase
[cfs] [cfs] [ %]
_1 -Year 12.52 _12.52 0.0%
2- Year...__ -� .._ 20.68 � _._ ___.. 20.68 0.0%
25 -Year 58.54 _ _
J. EASON, EI
5/23/2014

THE EDGE
RAV -13000
= => ROUTING RESULTS
SWMF #1 (Subbasin #l):
Top of Dam =
Return Period
I -Year
.._u�._
2 -Year
25-Year
100, Year_Worst Case _
Design Drainage Area =
Design Impervious Area =
% Impervious =
Design TSS Removal =
Top of Dam =
NWSE _
Surface Area Required at NWSE _
Surface Area at NWSE _
Average Depth _
WQ Volume Elevation =
Siphon Diameter =
Riser Size =
Riser Crest =
Orifice Elevation =
Orifice Diameter =
Barrel Diameter =
# of Barrels =
Invert In =
Invert Out =
Length =
Slope =
SUMMARY OF RESULTS
472.00 ft
Inflow Outflow Pvlax. WSE Freeboard
[cfs] [cfs] [ft] [ft]
20.44 0.32 468.21 3.79
e
u24.84 u _.- 0.38 - 468.79 3.21
39.34 8.88 470.09 1.91
47.92r 30.98 470.74 1.26
5.56 acres
3.94 acres
71.0%
90.0%
472.00 ft
466.00 ft
9,784 sf
10,949 sf
3.01 ft
467.06 ft
2.00 inches
4ftx4ft
469.80 ft
467.10 ft
2.50 inches
24 inches
1
465.00 feet
464.00 feet
95 feet
0.0105 ft/ft
J. EASON, EI
5/23/2014

THE EDGE SUMMARY OF RESULTS J. EASON, El
RAV -13000 5/23/2014
SWMF #2 (Subbasin #I):
Top of Dam =
477.00
Return Period
[cfs]
Inflow
.n _
1m00
[cf's]
1 -Year
-
1.25
92.19
2 -Year
22.05
77.55
25 -Year
35.63
V
_
$� ^100�Year Worst Case _
� _ �
_129.50
b 159.76
Design Drainage Area =
19.15
Design Impervious Area =
12.29
% Impervious =
64.2%
Design TSS Removal =
90.0%
Top of Dam =
477.00
NWSE =
469.00
Surface Area Required at NWSE =
30,879
Surface Area at NWSE =
33,542
Average Depth =
3.01
WQ Volume Elevation =
470.16
Siphon Diameter =
3.50
Riser Size =
4 ft x 4 ft
Riser Crest =
473.20
Orifice Elevation =
470.20
Orifice Diameter =
4.50
Barrel Diameter =
24
# of Barrels =
1
Invert In =
468.60
Invert Out =
468.00
Length =
113
Slope =
0.0053
ft
Outflow
Max. WSE
Freeboard
[cfs]
[ft]
[ft]
1m00
471.37
5.63
-
1.25
472.06
4.94
22.05
473.80
3.20
35.63
475.78
1.22
acres
acres
ft
ft
sf
sf
ft
ft
inches
ft
ft
inches
inches
feet
feet
feet
ft/ft

THE EDGE SUMMARY OF RESULTS J. EASON, El
RAV -13000 5/23/2014
SWMF #3 (Subbasin #3):
Top of Dam =
511.00
Return Period
f
Inflow
[cfs]
2 -Year
63.16
25 -Year
103.57
_ 100 _ -Year Worst Case
127.20
Design Drainage Area =
15.07
Design Impervious Area =
10.72
% Impervious =
71.1%
Design TSS Removal =
90.0%
Top of Dam =
511.00
NWSE =
503.00
Surface Area Required at NWSE =
26,625
Surface Area at NWSE =
28,560
Average Depth =
3.01
WQ Volume Elevation =
504.10
Siphon Diameter =
3.25
Riser Size =
4 ft x 4 ft
Riser Crest =
506.80
Orifice Elevation =
504.20
Orifice Diameter =
4.00
Barrel Diareter =
24
# of Barrels =
1
Invert Irr =
502.50
Invert Out =
502.00
Length =
59
Slope =
0.0085
T1
acres
acres
ft
ft
sf
sf
ft
ft
inches
ft
ft
inches
inches
feet
feet
feet
ft/ft
Outflow Max. WSE Freeboard
[cfs] [ft] [ft]
0.76.....,. 505.15 5.85
0.9_4 � 505.73 5.27
15.96 15.96 507.22_._._._ - • ~ --_-� -3.78
34.46 � � 508.62 -�� 2.78 �

THE EDGE SUMMARY OF RESULTS J. EASON, EI
RAV -13000 5/23/2014
SWMF #4 (Subbasin #3):
Top of Dam =
509.00
Return Period �
refs]
Inflow
FID
0.35
_[cfs]
1 -Year �^
0.44
2_2.83
2 -Year
10.42
28.47
25 -Year
47.54
100-Year Worst' aseT
y
58,65 Y�
Design Drainage Area =
7.03
Design Impervious Area =
4.74
% Lnpervious =
67.4%
Design TSS Removal =
90.0%
Top of'Dam =
509.00
NWSE =
502.50
Surface Area Required at NWSE =
11,841
Surface Area at NWSE =
14,609
Average Depth =
3.01
WQ Volume Elevation =
503.49
Siphon Diameter =
2.25
Riser Size =
4 ft x 4 ft
Riser Crest =
505.90
Orifice Elevation =
503.50
Orifice Diameter =
2.75
Barrel Diameter =
24
# of Barrels =
I
Invert In =
501.50
Invert Out =
501.00
Length =
77
Slope =
0.0065
ft
Outflow
Max. WSE
Freebo:
refs]
[ft]
[ft]
0.35
504.41
4.59
0.44
504.96
4.04
10.42
2.80
_506.20
507.03�������1.97
acres
acres
ft
ft
sf
sf
ft
ft
inches
ft
ft
inches
inches
feet
feet
feet
ft/ft

MISCELLANEOUS SITE INFORMATION
THE -EDGE
RAV -13000

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kml�d a&pr)fj) 0 2-n-12 laj)lf)

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STATE OF NORTH CAROLINA FIRM PANEL LOCATOR DIAGRAM
I
CASWELL ' 1 ((��O PE SON
V
- - -- - 03J- 6-- -- - - j-
- l--- 1 --- -il I °b' I04 "1
DATUM INFORMATION
The projection used in the preparation of this map was the North Carolina
State Plane (FIPSZONE 3200)• The horizontal datum was the North American
Datum of 1983, GRS80 ellipsoid. Differences in datum, ellipsoid, projection, or
Universal Transverse Mercator zones used in the production of FIRMS for adjacent
jurisdictions may result in slight positional differences in map features across
jurisdictional boundaries. These differences do not affect the accuracy of this
FIRM. All coordinates on this map are in U.S. Survey Feet, where
1 U.S. Survey Foot = 1200/3937 Meters.
Flood elevations on this map are referenced to the North American Vertical
Datum of 1988 (NAVD 88), These flood elevations must be compared to structure
and ground elevations referenced to the same vertical datum, An average
offset between NAVD 88 and the National Geodetic Vertical Datum of 1929
(NGVD 29) has been computed for each North Carolina county. This offset was
then applied to the NGVD 29 flood elevations that were not revised during the
creation of this statewide format FIRM. The offsets for each county shown on
this FIRM panel are shown in the vertical datum offset table below. Where a
county boundary and a flooding source with unrevised NGVD 29 flood elevations
are coincident, an individual offset has been calculated and applied during the
creation of this statewide format FIRM, See Section 6.1 of the accompanying
Flood Insurance Study report to obtain further information on the conversion
of elevations between NAVD 88 and NGVD 29. To obtain current elevation,
description, and /or location information for bench marks shown on this map,
please contact the North Carolina Geodetic Survey at the address shown below.
You may also contact the Information Services Branch of the National Geodetic
Survey at (301) 713 -3242, or visit its website at www.ngs.noaa.gov,
North Carolina Geodetic Survey County Average Vertical Datum Offset Table
121 West Jones Street County Vertical Datum Offset Ift)
Raleigh, NC 27601 Orange -0.79
[phone]
www, ncgs,state.nc.us
Example: NAVD 88 - NGVD 29 + ( -0.79)
All streams listed in the Flood Hazard Data Table below were studied by
detailed methods using field survey. Other flood hazard data shown on this
map may have been derived using either a coastal analysis or limited detailed
riverine analysis. More information on the flooding sources studied by these
analyses is contained in the Flood Insurance Study report.
FLOOD HAZARD DATA TABLE
Floodway Width (feet)
Left/Right Distance From Stream to v-
Center of S
E ncroachment Boundary
(Looking Downstream) or
Tot8l Floodway width
J
c3`3
ao;
e
BOOKER CREEK
1 1 7
11,747
1 ,840
297.4
749 / 320
240
�C
Qj
L)�o
�`bg�
olip
eta
24,505
b�
,�to
��a
��
O`c5
, •�B;
- l--- 1 --- -il I °b' I04 "1
DATUM INFORMATION
The projection used in the preparation of this map was the North Carolina
State Plane (FIPSZONE 3200)• The horizontal datum was the North American
Datum of 1983, GRS80 ellipsoid. Differences in datum, ellipsoid, projection, or
Universal Transverse Mercator zones used in the production of FIRMS for adjacent
jurisdictions may result in slight positional differences in map features across
jurisdictional boundaries. These differences do not affect the accuracy of this
FIRM. All coordinates on this map are in U.S. Survey Feet, where
1 U.S. Survey Foot = 1200/3937 Meters.
Flood elevations on this map are referenced to the North American Vertical
Datum of 1988 (NAVD 88), These flood elevations must be compared to structure
and ground elevations referenced to the same vertical datum, An average
offset between NAVD 88 and the National Geodetic Vertical Datum of 1929
(NGVD 29) has been computed for each North Carolina county. This offset was
then applied to the NGVD 29 flood elevations that were not revised during the
creation of this statewide format FIRM. The offsets for each county shown on
this FIRM panel are shown in the vertical datum offset table below. Where a
county boundary and a flooding source with unrevised NGVD 29 flood elevations
are coincident, an individual offset has been calculated and applied during the
creation of this statewide format FIRM, See Section 6.1 of the accompanying
Flood Insurance Study report to obtain further information on the conversion
of elevations between NAVD 88 and NGVD 29. To obtain current elevation,
description, and /or location information for bench marks shown on this map,
please contact the North Carolina Geodetic Survey at the address shown below.
You may also contact the Information Services Branch of the National Geodetic
Survey at (301) 713 -3242, or visit its website at www.ngs.noaa.gov,
North Carolina Geodetic Survey County Average Vertical Datum Offset Table
121 West Jones Street County Vertical Datum Offset Ift)
Raleigh, NC 27601 Orange -0.79
[phone]
www, ncgs,state.nc.us
Example: NAVD 88 - NGVD 29 + ( -0.79)
All streams listed in the Flood Hazard Data Table below were studied by
detailed methods using field survey. Other flood hazard data shown on this
map may have been derived using either a coastal analysis or limited detailed
riverine analysis. More information on the flooding sources studied by these
analyses is contained in the Flood Insurance Study report.
FLOOD HAZARD DATA TABLE
Floodway Width (feet)
Left/Right Distance From Stream to v-
Center of S
E ncroachment Boundary
(Looking Downstream) or
Tot8l Floodway width
Cross
Section
Stream
Statlon'
-lood Discharge
(cfs)
°k
1 Annual Chance
000yrearl
✓Vater -Surface Elevation
(feet NAVD 881
BOOKER CREEK
1 1 7
11,747
1 ,840
297.4
749 / 320
240
23,991
1 210
434.8
19 / 1 23
245
24,505
1 210
442.4
14 / 47
250
24,963
1 1,010
449.4
1 19 / 12
255
25,524
1 ,01 0
461.3
19 / 1 3
267
26,670
1 010
1 479.2
50 / 20
CEDAR FORK
007
668
1 ,11 0
297.4
19 / 80
013
1,315
1 J 1 0
298.3
33 / 16
022
2.215
1 ,1 1 0
311.4
17 / 1 5
024
2,412
1 ,1 1 0
314.3
19 / 1 2
026
2,576
1 ,11 0
319.4
22 / 13
028
2,839
1 ,11 0
328.4
14 / 17
031
3,050
940
333.6
20 / 45
033
3,252
940
337.8
18 / 20
034
3,434
940
341.4
9 / 16
036
3,631
940
353.2
9 / 30
039
3,897
940
367.6
28 / 17
041
4,143
940
379.3
24 / 12
044
4,365
940
383.7
16 / 24
046
4,595
940
393.0
34 / 15
048
4,762
940
398.9
33 / 51
049
4,944
940
405.1
28 / 28
052
5,190
940
415.3
35 / 39
055
5,482
940
425.2
12 / 12
057
5,732
940
435.5
18 / 41
061
6,061
940
441.2
16 / 25
063
6,308
940
445.5
11 / 16
068
6,796
940
458.3
16 / 24
073
7,325
731
467.5
17 / 26
079
7,865
1 731
477.2
18 / 25
082
8,152
1 731
484.3
65 / 30
085
8,509
1 731
1 484.3
21 / 25
' Feet above mouth 2 E levation includes backwater effects from Booker Creek
�d�s�o �,� ,vkr.t ✓�
T.
r: r
1
FEMNS COOPERATING TECHNICAL PARTNER
awl' A7vD S�
This digital Flood Insurance Rate Map (FIRM) was produced through a unique
cooperative partnership between the State of North Carolina and the Federal
Emergency Management Agency (FEMA). The State of North Carolina has
implemented a long term approach of floodplain management to decrease
the costs associated with flooding. This is demonstrated by the State's com-
mitment floodplain t th local level. A part of this effort the
m tment to ma areas a e s a a ,
P
P
State of North Carolina has joined In a Cooperating Technical State agreement
ment
with FEMA to produce and maintain this digital FIRM.
www.ncfloodmtaps.com
79° 04' 00 79.03' 30 79° 03' 00" 79° 02' 30"
1980 000 FEET 675 0O "^ 676 000 M 1 987 500 FEET 677 000 Ia 1 990 000 FEET
JOINS PANEL 9881
810 000 FEET _ ._.. -- - --------- - - - - -- - - - - - -- - -- -- -- - - - - -- - - - - --- -- -- ,, 810 000 FEET
- 3983 ^"
°58' 30' � t•' ' I ,, rua
35� 35.58'30'
000
•
i .
.o
u.
[!� Y
,
I-. t,,
r .
,
OG
>92A r
LW AA D,:
k
A, :. _ �t ". � i �i a.• A15 lf!t.t 1 _•¢ Sc•I 4 1 t• �l�h' \�.
� F
x , i
-
4
/
n (f(lrL
• 111 ,� nn - C � .: ';� I "it•1 �° .. /5� "" � :. �. \' 1 � -
tl/
rt yl"` v�' � - ^. 1 . �i..�= �' �, >I::i ii ,rl] \•L I.., �, ® ' ~�
+.. r ',r ply %� �K �' i r�l ��� - 4 �,..
r
L� X': L '6E . i�
�l 3981 000
1�
•
,
•t�
0%,
F7 -a
a
j r It T.
ZONE X ,
ZONE AE, -
<6i
'.LILT CF , T,�,I
ZONE X
zf .,; s�� ! . `Af3Ny _ -
EZ2 0 TI ,I,
35 °57' 00"
ZONE X
ZONE AE'
3980 Ow m i 1
91
J
d p ZONE X
800 000 FEET - -- - - - - -- -.- -__ . _\ i'g--
1980 000 FEET 165 --
79'04'00" 79 °03' 30"
1982 500 FEET
This map is for use in administering the National Flood Insurance Program. It does not
necessarily identify all areas subject to flooding, particularly from local drainage sources
of small size, The community map repository should be consulted for possible
updated or additional flood hazard information.
To obtain more detailed information in areas where Base Flood Elevations (BFEs)
and /or floodways have been determined, users are encouraged to consult the Flood
Profiles, Floodway Data, Limited Detailed Flood Hazard Data, and /or Summary of Stillwater
Elevations tables contained within the Flood Insurance Study (FIS) report that accompanies
this FIRM. Users should be aware that BFEs shown on the FIRM represent rounded
whole -foot elevations. These BFEs are intended for flood insurance rating purposes
only and should not be used as the sole source of flood elevation information. Accordingly,
flood elevation data presented in the FIS report should be utilized in conjunction with
the FIRM for purposes of construction and /or floodplain management.
Boundaries of regulatory floodways shown on the FIRM for flooding sources studied
by detailed methods were computed at cross sections and interpolated between cross
sections. The floodways were based o
n hydraulic considerations with regard to requirements
of the National Flood Insurance Program. Floodway widths and other pertinent floodway
data for flooding sources studied by detailed methods as well as non - encroachment widths
for flooding sources studied by limited detailed methods are provided in the FIS report
for this jurisdiction. The FIS report also provides instructions for determining a floodway
using non -encroachment widths for flooding sources studied by limited detailed methods.
37
ZONE X
r
Lis
ZONE X
IF
r
- D11
D <it
'ZONE X' ok'6`\�
f "f''
a
on,
JOINS PANEL 9789 676 Ow M
79° 03' 00 "
NOTES TO USERS
Certain areas not in Special Flood Hazard Areas may be protected by flood control This map reflects more detailed and up -to -date stream channel configurations than
structures. Refer to Section 4.4 "Flood Protection Measures" of the Flood Insurance those shown on the previous FIRM for this jurisdiction. The floodplains and floodways
Study report for information on flood control structures in this jurisdiction, that were transferred from the previous FIRM may have been adjusted to conform to
these new stream channel configurations. As a result, the Flood Profiles and Floodway
Base map information and geospatial data used to develop this FIRM were obtained from Data tables in the Flood Insurance Study report (which contains authoritative hydraulic
various organizations, including the participating local community(ies), state and federal data) may reflect stream channel distances that differ from what is shown on this map.
agencies, and /or other sources. The primary base for this FIRM is aerial imagery acquired by
Orange County. The time period of collection for the imagery is 2003. Information and Please refer to the separately printed Map Index for an overview map of the county
geospatial data supplied by the local community(ies) that met FEMA base map specifications showing the layout of map panels, community map repository addresses, and a Listing of
were considered the preferred source for development of the base map. See geospatial Communities table containing National Flood Insurance Program dates for each community
metadata for the associated digital FIRM for additional information about base map as well as a listing of the panels on which each community is located.
preparation.
If you have questions about this map, or questions concerning the National Flood
Base map features shown on this map, such as corporate limits, are based on the Insurance Program in general, please call 1. 877 -FEMA MAP (1-877-336-2627) or visit the
most up -to -date data available at the time of publication. Changes in the corporate FEMA website at www.fema.gov.
limits may have occurred since this map was published. Map users should
consuItthe appropriate community official or website to verify
current conditions o f An accompanying F lood Insurance Study report, ,
L ett er of Ma p Revision ( L MR )
o r Le tt
er
jurisdictional boundaries and base map features: This map may contain roads that were of Map Amendment (LOMA) revising portions of this panel, and digital versions of this
not considered in the hydraulic analysis of streams where no new hydraulic model was FIRM may be available. Visit the North Carolina Floodplain Mapping Program website
created during the production of this statewide format FIRM. at www.ncfloodmaps.com, or contact the FEMA Map Service Center at 1,800 -358 -9616
for information on all related products associated with this FIRM. The FEMA Map Service
Center may also be reached by Fax at 1- 800 - 358 -9620 and its website at www,msc.fema,gov,
35'57'00"
FLOODING EFFECTS
FROM CEDAR FORK
ZONE AE
as -; (EL 298)
3980 000 M
800 000 FEET
Go 000 FEET
N LAKESHORE DR
MAP REPOSITORY
Refer to listing of Map Repositories on Map Index or visit www.nefloodmaps.com.
EFFECTIVE DATE OF FLOOD INSURANCE RATE MAP PANEL
FEBRUARY 2, 2007
EFFECTIVE DATES) OF REVISIONS) TO THIS PANEL
For community map revision history prior to statewide mapping, refer to the Community Map
j
History table located in the Flood Insurance Study report f or this jurisdiction.
To determine if flood insurance is available in this community, your insuranc e
agent, the
North Carolina Division of Emergency Management or the National Flood Insurance Program at the
following phone numbers or websites:
NC Division of Emergency Management National Flood Insurance Program
(919) 715 -8000 www.nccrimecontrol.org /nfi 1 -800- 638 -6620 www.fema.gov/nfip
LEGEND
SPECIAL FLOOD HAZARD AREAS (SFHAs) SUBJECT TO
INUNDATION BY THE 1 0 � ANNUAL CHANCE FLOOD
The 1 % annual chance flood 000 -year flood), also known as the base flood, is the flood
that has a 1 % chance of being equaled or exceeded in any given year. The Special
Flood Hazard Area is the area subject to flooding by the 1 % annual chance flood. Areas
of Special Flood Hazard include Zones A, AE, AH, AO, AR, A99, V, and VE. The Base
Flood Elevation is the water - surface elevation of the 1 °� annual chance flood.
ZONE A No Base Flood Elevations determined.
ZONE AE Base Flood Elevations determined.
ZONE AH f=lood depths of 1 to 3 feet (usually areas of ponding); Base Flood
Elevations determined.
ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain);
average depths determined. For areas of alluvial fan flooding, velocities
also determined.
ZONE AR Special Flood Hazard Area formerly protected from the 1% annual
chance flood by a flood control system that was subsequently
decertified. Zone AR indicates that the former flood control system is
being restored to provide protection from the 1% annual chance or
greater flood.
ZONE A99 Area to be protected from 1 % annual chance flood by a Federal
flood protection system under construction; no Base Flood Elevations
determined.
ZONE VE Coastal flood zone with velocity hazard (wave action); Base Flood Elevations
determined.
® FLOODWAY AREAS IN ZONE AE
The floodway is the channel of a stream plus any adjacent floodplain areas that must be
kept free of encroachment so that the 1 % annual chance flood can be carried without
substantial increases in flood heights.
OTHER FLOOD AREAS
ZONE X Areas of 0.2% annual chance flood; areas of 1% annual chance flood
with average depths of less than 1 foot or with drainage areas less than
1 square mile; and areas protected by levees from 1 % annual chance
flood.
OTHER AREAS
ZONE X Areas determined to be outside the 0.2% annual chance floodplain.
ZONE D Areas in which flood hazards are undetermined, but possible.
COASTAL BARRIER RESOURCES SYSTEM (CBRS) AREAS
\' \ OTHERWISE PROTECTED AREAS (OPAs)
CBRS areas and OPAs are normally located within or adiacent to Special Flood Hazard Areas.
- 1% annual chance floodplain boundary
0.2% annual chance floodplain boundary
Floodway boundary
Zone D Boundary
9.0.0.0.0.0.0.0.000• CBRS and OPA boundary
Boundary dividing Special Flood Hazard Area Zones and
"- 4- boundary dividing Special Flood Hazard Areas of different
- Base Flood Elevations, flood depths or flood velocities.
5 13- Base Flood Elevation line and value; elevation in feet*
(EL 987) Base Flood Elevation value where uniform within zone;
elevation in feet*
"Referenced to the No American Vertical Datum of 1988
n Cross section line
23 - - - - - - 23 Transect line
97 °07' 30" ° 32 °22' 30" Geographic coordinates referenced to the North American
Datum of 1983 (NAD 83)
4276 000m 1000 -meter Universal Transverse Mercator grid ticks, zone 18
t 477 500 FEET 2500 -foot grid values: North Carolina State Plane coordinate
system (FIPSZONE 3200, State Plane NAD 83 feet)
BM5510 North Carolina Geodetic Survey bench mark (see explanation
X in the Datum Information section of this FIRM panel).
BM5510 National Geodetic Survey bench mark (see explanation in
® the Datum Information section of this FIRM panel).
• M1.5 River Mile
4
GRID NORTH
MAP SCALE 1" = 500' (1 : 6,000)
250 0 500 1000
FEET
EEa METERS
150 0 150 300
PANEL 9880J
FIRM
FLOOD INSURANCE RATE MAP
NORTH CAROLINA
PANEL 9880
(SEE LOCATOR DIAGRAM OR MAP INDEX FOR FIRM
PANEL LAYOUT)
CONTAINS:
COMMUNITY CID No. PANEL SUFFIX
CHAPEL HILL, TOWN OF 370180 9880 1
ORANGE COUNTY 370342 9880 1
Notice to User: The Map Number shown below should be used
when placing map orders: the Community Number shown
above should be used on insurance applications for the subject
community.
EFFECTIVE DATE MAP NUMBER
FEBRUARY 2, 2007 3710988000J
IS
�.
State of North Carolina
Federal Emergency Management Agency
ED
O
St
IN
ri
O
am

STATE OF NORTH CAROLINA FIRM PANEL LOCATOR DIAGRAM
—� -�
ItloodwtDistah From
Left/Right Distance From
the Center of Stream to
Encroachment Boundary
(Looking Downstream)
or Total Floodw ay Width
Cross
Sec:lon
Stream
Station'
Flood Discharge
(cfs)
PE
SON
350
34, 977
2,240
453.8
17/15
355
35,477
2,240
455 -1
17/15
360
35,977
2,240
457.0
17/15
365
36,477
1,890
459.1
35/35
370
36,977
1,890
460.7
30/60
375
37,541
1,890
463.3
35/.50
380
37,977
1,6W
466.5
25/70
385
38,477
•
- -.._.
3�
DATUM INFORMATION
The projection used in the preparation of this map was the North Carolina
State Plane (FIPSZONE 3200). The horizontal datum was the North American
Datum of 1983, GRS80 ellipsoid. Differences in datum, ellipsoid, projection, or
Universal Transverse Mercator zones used in the production of FIRMs for adjacent
jurisdictions may result in slight positional differences in map features across
jurisdictional boundaries. These differences do not affect the accuracy of this
FIRM. All coordinates on this map are in U.S. Survey Feet, where
1 U.S. Survey Foot = 1200/3937 Meters.
Flood elevations on this map are referenced to the North American Vertical
Datum of 1988 (NAVD 88), These flood elevations must be compared to structure
and ground elevations referenced to the same vertical datum. An average
offset between NAVD 88 and the National Geodetic Vertical Datum of 1929
(NGVD 29) has been computed for each North Carolina county, This offset was
then applied to the NGVD 29 flood elevations that were not revised during the
creation of this statewide format FIRM. The offsets for each county shown on
this FIRM panel are shown in the vertical datum offset table below. Where a
county boundary and a flooding source with unrevised NGVD 29 flood elevations
are coincident, an individual offset has been calculated and applied during the
creation of this statewide format FIRM, See Section 6.1 of the accompanying
Flood Insurance Study report to obtain further information on the conversion
of elevations between NAVD 88 and NGVD 29. To obtain current elevation,
description, and /or location information for bench marks shown on this map,
please contact the North Carolina Geodetic Survey at the address shown below.
You may also contact the Information Services Branch of the National Geodetic
Survey at (301) 713 -3242, or visit its website at www,ngs.noaa.gov,
North Carolina Geodetic Survey County Average Vertical Datum Offset Table
121 West Jones Street County Vertical Datum Offset (ft)
Raleigh, NC 27601 Orange - 0.79
(919) 733 -3836
www, ncgs, state.nc, us
I Example: NAVD 88 - NGVD 29 + ( -0.79)
All streams listed in the Flood Hazard Data Table below were studied by
detailed methods using field survey. Other flood hazard data shown on this
map may have been derived using either a coastal analysis or limited detailed
riverine analysis. More information on the flooding sources studied by these
analyses is contained in the Flood Insurance Study report.
FLOOD HAZARD DATA TABLE
,
tttd.v�:CX)PERATMCi 1tG11NICAL. ARINtH ,c• �
�qND SE��
This digital Flood Insurance Rate Map (FIRM) was produced through a unique
cooperative partnership between the State of North Carolina and the Federal
Emergency Management Agency (FEMA). The State of North Carolina has
implemented a long term approach of floodplain management to decrease
the costs associated with flooding. This is demonstrated by the State's com-
mitment to map floodplain areas at the local level. As a part of this effort, the
State of North Carolina has joined in a Cooperating Technical S late agreement
reement
with FEMA to produce and maintain this digital FIRM.
www.ndloodmaps.com
79° 06' 00 "
1970 000 FEET
810 000 FEET F, - -- - - - - --
35° 58' 30 "
3982 000 M
35° 58' Oi
i
79 °05' 30"
672 000 ?,A
MW
JOINS PANEL 9871
FLOODING EFFECTS FROM
79* 05' 00" 79 °04. 30" 00o M 1 980 000 FEET OIL FIELD CREEK
673 0� "' 1 977 500 FEET �S� 674 ����
___ -- -- —_ -- _ —.-
810 000 FEET
A.: ZONE AE
e IEL 452)
I
Orange County
35 58 30
Unincorporated Area ��; ZONE X'
370342
"`--`-Orange County
ZONE AE
,o: _-ZONE X
Unincorporated Areas
1'0Nv n of (:hapel Hill
370342
Extra.ter)'ltorial Jurisdiction
370180
ZONE Xi <l.,r /iwr, 0'w/
( ZONE X C i CO- iY
--
�� 0
Orange (01-trIty \ ,ZONE X
Uiti.ncotporated Areas I ,,
3 %0342 Town of C1- apcl Hill
' \ZONE AE 370180
' .,
ZONE X T
T F)FT .n T '
ZONE X
807 500 FEET
ZONE AE
0
LLJ
t
O
II
1C)1 "VIC- FIl1i'i.L ;'I�_ LT,:
ZONE X
L_
\_Z41 Town of Carrboro Extraterritorial Jurisdictio
370275
-ZONE AE
*ZE
a i T 4 8 oaa
3981 000 M
35.57' 30 ° � ..
Town of Chapel Hill_
� LII:'IT l, I L, L.,,, A\ .
EXLralCTrlltlrtctl Jll l'1ShcCllc Il
i osi
170180
711 y
•I ZONE X'
TL T Tf
t
\ZONE AE ZONE AE ' t 1 l
tt
802 500 1 1 I / I _ � � ` iZGivE n
-
ZONE X ZONE X
Town of Carrboro \, -
Extraterritorial l\ t "'r
Jurlsdlctlon ZONE x — _ ` -' _
370275 1'0�, n of Carrboro ZONE x
X70275
_�%% \ �\� - -ZONE X
F.'rr /rr C i:,,. /. 2• .. �.._ 3�0 ; ``' (J1� J i I - I - T- I f
ZONE AE
ZONE :x ZONE X ti `� X�`
ZONE AE
Hogan Lake
ZONE X
35 °57' 00" a -
3980 000 M / / ff i i F\ N ( ') Iii N : )
aoo \ ZONE X- \1 1 :, r 0AN 0: CI i /\PEL .� !
ZONE :AE
ZONE X
R \\
B00 000 FEET F11 L INF -
1970 000 FEET 1672 o0o n JOINS PANFi Q779
79 °06'00•• 1972 500 FEET 79 °05'30" C',0 t9 °04'30"
J
This map is for use in administering the National Flood Insurance Program, It does not
necessarily identify all areas subject to flooding, particularly from local drainage sources
of small size. The community map repository should be consulted for possible
updated or additional flood hazard information.
To obtain more detailed information in areas where Base Flood Elevations (BFEs)
and /or floodways have been determined, users are encouraged to consult the Flood
Profiles, Floodway Data, Limited Detailed Flood Hazard Data, and /or Summary of Stillwater
Elevations tables contained within the Flood Insurance Study (FIS) report that accompanies
this FIRM. Users should be aware that BFEs shown on the FIRM represent rounded
whole -foot elevations. These BFEs are intended for flood insurance rating purposes
only and should not be used as the sole source of flood elevation information. Accordingly,
flood elevation data presented in the FIS report should be utilized in conjunction with
the FIRM for purposes of construction and /or floodplain management.
Boundaries of regulatory floodways shown on the FIRM for flooding sources studied
by detailed meth ods wer e computed d at cross sections and interpolated between cross
sect ions. The flo od wa Y s we re based on hydraulic c consideration s with regard to requirements
n
is
of the National Flood Insurance Program, Floodway widths and other pertinent floodway
data for flooding sources studied by detailed methods as well as non - encroachment widths
for flooding sources studied by limited detailed methods are provided in the FIS report
for this jurisdiction. The FIS report also provides instructions for determining a floodway
using non - encroachment widths for flooding sources studied by limited detailed methods.
NOTES TO USERS
Certain areas not in Special Flood Hazard Areas may be protected by flood control This map reflects more detailed and up -to -date stream channel configurations than
structures. Refer to Section 4,4 "Flood Protection Measures" of the Flood Insurance those shown on the previous FIRM for this jurisdiction. The floodplains and floodways
Study report for information on flood control structures in this jurisdiction. that were transferred from the previous FIRM may have been adjusted to conform to
these new stream channel configurations. As a result, the Flood Profiles and Floodway
Base map information a n d geospatial data used to develop t hi s F I RM were obta i ned from Data tables in the Flood I nsura n ce Study report (which h contains authoritative h dr au
lic
various organizations, including the participating local community(ies), state and federal data) may reflect stream channel distances that differ from what is shown on this map.
agencies, and /or other sources. The primary base for this FIRM is aerial imagery acquired by
Orange County. The time period of collection for the imagery is 2003. Information and Please refer to the separately printed Map Index for an overview map of the county
geospatial data supplied by the local community(ies) that met FEMA base map specifications showing the layout of map panels, community map repository addresses, and a Listing of
were considered the preferred source for development of the base map. See geospatial Communities table containing National Flood Insurance Program dates for each community
metadata for the associated digital FIRM for additional information about base map as well as a listing of the panels on which each community is located.
preparation.
If you have questions about this map, or questions concerning the National Flood
Base map features shown on this map, such as corporate limits, are based on the Insurance Program in general, please call 1- 877 -FERA MAP (1-877 -336 -2627) or visit the
most up -to -date data available at the time of publication. Changes in the corporate FEMA website at www.fema.gov,
limits may have occurred since this map was published. Map users should
consult the appropriate community official or website to verify current conditions of An accompanying Flood Insurance Study report, Letter of Map Revision (LOMR) or Letter
jurisdictional boundar i es and base map f eatures Th i s map may contain roads that were of Ma p Amendment ( L O MA ) revising P ort i ons o f th i s panel, and digital vers i ons o f this
not considered in the hydraulic analysis of streams where no new hydraulic model was FIRM may be available. Visit the North Carolina Floodplain Mapping Program website
created during the production of this statewide format FIRM. at www.ncfloodmaps.com, or contact the FEMA Map Service Center at 1,800 -358 -9616
for information on all related products associated with this FIRM. The FEMA Map Service
Center may also be reached by Fax at 1- 800 -358 -9620 and its website at www,msc,fema.gov,
i °57' 00"
3980 0O m
310 000 FE_T
MAP REPOSITORY
Refer to listing of Map Repositories on Map Index or visit www.ncfloodmaps.com.
INS CE ATE MAP
F FLOOD IN E R PANEL
EFFECTIVE DATE O LO
FEBRUARY 2,2007
EFFECTIVE DATES) OF REVISIONS) TO THIS PANEL
statewide in refer to the Community Ma
For community map revision history prior to slat mapping, ty p
History table located in the Flood Insurance Study report for this jurisdiction.
To determine if flood insurance Is available le in th i s community, contact your in sura n ce agent,
the
North Carolina Division of Emergency Management or the National Flood Insurance Program at the
following phone numbers or websites:
NC Division of Emergency Management National Flood Insurance Program
(919) 715 -8000 www.nccrimecontrol.org /nfip 1- 800 - 638 -6620 www.fema.goy/nfip
LEGEND
SPECIAL FLOOD HAZARD AREAS (SFHAs) SUBJECT TO
INUNDATION BY THE 1% ANNUAL CHANCE FLOOD
The 1 % annual chance flood (100 -year flood), also known as the base flood, is the flood
that has a 1 % chance of being equaled or exceeded in any given year. The Special
Flood Hazard Area is the area subject to flooding by the 1% annualchance flood. Areas
of Special Flood Hazard include Zones A, AE, AH, AO, AR, A99, V, and VE. The Base
Flood Elevation is the water - surface elevation of the 1% annual chance flood.
ZONE A No Base Flood Elevations determined.
ZONE AE Base Flood Elevations determined.
ZONE AH Flood depths of 1 to 3 feet (usually areas of ponding); Base Flood
Elevations determined.
ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain);
average depths determined. For areas of alluvial fan flooding, velocities
also determined.
ZONE AR Special Flood Hazard Area formerly protected from the 1% annual
chance flood by a flood control system that was subsequently
decertified. Zone AR indicates that the former flood control system is
being restored to provide protection from the 1% annual chance or
greater flood.
ZONE A99 Area to be protected from 1 % annual chance flood by a Federal
flood protection system under construction; no Base Flood Elevations
determined.
ZONE VE Coastal flood zone with velocity hazard (wave action); Base Flood Elevations
determined.
FLOODWAY AREAS IN ZONE AE
The floodway is the channel of a stream plus any adjacent floodplain areas that must be
kept free of encroachment so that the 1 % annual chance flood can be carried without
substantial increases in flood heights.
OTHER FLOOD AREAS
ZONE X Areas of 0.2% annual chance flood; areas of 1% annual chance flood
with average depths of less than 1 foot or with drainage areas less than
1 square mile; and areas protected by levees from 1 % annual chance
flood.
OTHER AREAS
ZONE X Areas determined to be outside the 0.2% annual chance floodplain.
ZONE D Areas in which flood hazards are undetermined, but possible.
® COASTAL BARRIER RESOURCES SYSTEM (CBRS) AREAS
OTHERWISE PROTECTED AREAS (OPAs)
CBRS areas and OPAs are normally located within or adjacent to Special Flood Hazard Areas.
1% annual chance floodplain boundary
0.2% annual chance floodplain boundary
— — — — Floodway boundary
Zone D Boundary
•������������������• CBRS and OPA boundary
Boundary dividing Special Flood Hazard Area Zones and
boundary dividing Special Flood Hazard Areas of different
Base Flood Elevations, flood depths or flood velocities.
_513— Base Flood Elevation line and value; elevation in feet*
(EL 987) Base Flood Elevation value where uniform within zone;
elevation in feet*
*Referenced to the North American Vertical Datum of 1988
Cross section line
23 - - - - - - 23 Transect line
97° 07' 30" , 32° 22' 30 ^ Geographic coordinates referenced to the North American
Datum of 1983 (NAD 83)
4276 000m 1000 -meter Universal Transverse Mercator grid ticks, zone 18
1 477 500 FEET 2500 -foot rid values: North Carolina State Plane coordinate
system (FIPSZONE 3200, State Plane NAD 83 feet)
BM5510 North Carolina Geodetic Survey bench mark (see explanation
X in the Datum information section of this FIRM panel).
BM5510 National Geodetic Survey bench mark (see explanation in
® the Datum Information section of this FIRM panel).
• M1.5 River Mile
4
GRID NORTH
MAP SCALE 1" = 500' (1 6,000)
250 0 Soo 1000
FEET
METERS
150 0 150 300
ItloodwtDistah From
Left/Right Distance From
the Center of Stream to
Encroachment Boundary
(Looking Downstream)
or Total Floodw ay Width
Cross
Sec:lon
Stream
Station'
Flood Discharge
(cfs)
1% Annual Chance
(100 -year)
Water - Surface Elevation
(feet NAVD 88)
BOLIN CREEK
350
34, 977
2,240
453.8
17/15
355
35,477
2,240
455 -1
17/15
360
35,977
2,240
457.0
17/15
365
36,477
1,890
459.1
35/35
370
36,977
1,890
460.7
30/60
375
37,541
1,890
463.3
35/.50
380
37,977
1,6W
466.5
25/70
385
38,477
1,630
468.5
40/40
390
38,977
1,630
472.4
50/30
395
39,515
1,630
476.7
50/40
400
39,995
1,630
477.4
250/13
405
40, 514
1, 630
488.4
200/100
JONES CREEK
006
550
NA
466.2
100
021
2,130
NA
479.8
70
OLD FIELD CREEK
109
10,880
NA
462.2
50
130
13,000
NA
475.6
70
'Feet abo\e mouth
,
tttd.v�:CX)PERATMCi 1tG11NICAL. ARINtH ,c• �
�qND SE��
This digital Flood Insurance Rate Map (FIRM) was produced through a unique
cooperative partnership between the State of North Carolina and the Federal
Emergency Management Agency (FEMA). The State of North Carolina has
implemented a long term approach of floodplain management to decrease
the costs associated with flooding. This is demonstrated by the State's com-
mitment to map floodplain areas at the local level. As a part of this effort, the
State of North Carolina has joined in a Cooperating Technical S late agreement
reement
with FEMA to produce and maintain this digital FIRM.
www.ndloodmaps.com
79° 06' 00 "
1970 000 FEET
810 000 FEET F, - -- - - - - --
35° 58' 30 "
3982 000 M
35° 58' Oi
i
79 °05' 30"
672 000 ?,A
MW
JOINS PANEL 9871
FLOODING EFFECTS FROM
79* 05' 00" 79 °04. 30" 00o M 1 980 000 FEET OIL FIELD CREEK
673 0� "' 1 977 500 FEET �S� 674 ����
___ -- -- —_ -- _ —.-
810 000 FEET
A.: ZONE AE
e IEL 452)
I
Orange County
35 58 30
Unincorporated Area ��; ZONE X'
370342
"`--`-Orange County
ZONE AE
,o: _-ZONE X
Unincorporated Areas
1'0Nv n of (:hapel Hill
370342
Extra.ter)'ltorial Jurisdiction
370180
ZONE Xi <l.,r /iwr, 0'w/
( ZONE X C i CO- iY
--
�� 0
Orange (01-trIty \ ,ZONE X
Uiti.ncotporated Areas I ,,
3 %0342 Town of C1- apcl Hill
' \ZONE AE 370180
' .,
ZONE X T
T F)FT .n T '
ZONE X
807 500 FEET
ZONE AE
0
LLJ
t
O
II
1C)1 "VIC- FIl1i'i.L ;'I�_ LT,:
ZONE X
L_
\_Z41 Town of Carrboro Extraterritorial Jurisdictio
370275
-ZONE AE
*ZE
a i T 4 8 oaa
3981 000 M
35.57' 30 ° � ..
Town of Chapel Hill_
� LII:'IT l, I L, L.,,, A\ .
EXLralCTrlltlrtctl Jll l'1ShcCllc Il
i osi
170180
711 y
•I ZONE X'
TL T Tf
t
\ZONE AE ZONE AE ' t 1 l
tt
802 500 1 1 I / I _ � � ` iZGivE n
-
ZONE X ZONE X
Town of Carrboro \, -
Extraterritorial l\ t "'r
Jurlsdlctlon ZONE x — _ ` -' _
370275 1'0�, n of Carrboro ZONE x
X70275
_�%% \ �\� - -ZONE X
F.'rr /rr C i:,,. /. 2• .. �.._ 3�0 ; ``' (J1� J i I - I - T- I f
ZONE AE
ZONE :x ZONE X ti `� X�`
ZONE AE
Hogan Lake
ZONE X
35 °57' 00" a -
3980 000 M / / ff i i F\ N ( ') Iii N : )
aoo \ ZONE X- \1 1 :, r 0AN 0: CI i /\PEL .� !
ZONE :AE
ZONE X
R \\
B00 000 FEET F11 L INF -
1970 000 FEET 1672 o0o n JOINS PANFi Q779
79 °06'00•• 1972 500 FEET 79 °05'30" C',0 t9 °04'30"
J
This map is for use in administering the National Flood Insurance Program, It does not
necessarily identify all areas subject to flooding, particularly from local drainage sources
of small size. The community map repository should be consulted for possible
updated or additional flood hazard information.
To obtain more detailed information in areas where Base Flood Elevations (BFEs)
and /or floodways have been determined, users are encouraged to consult the Flood
Profiles, Floodway Data, Limited Detailed Flood Hazard Data, and /or Summary of Stillwater
Elevations tables contained within the Flood Insurance Study (FIS) report that accompanies
this FIRM. Users should be aware that BFEs shown on the FIRM represent rounded
whole -foot elevations. These BFEs are intended for flood insurance rating purposes
only and should not be used as the sole source of flood elevation information. Accordingly,
flood elevation data presented in the FIS report should be utilized in conjunction with
the FIRM for purposes of construction and /or floodplain management.
Boundaries of regulatory floodways shown on the FIRM for flooding sources studied
by detailed meth ods wer e computed d at cross sections and interpolated between cross
sect ions. The flo od wa Y s we re based on hydraulic c consideration s with regard to requirements
n
is
of the National Flood Insurance Program, Floodway widths and other pertinent floodway
data for flooding sources studied by detailed methods as well as non - encroachment widths
for flooding sources studied by limited detailed methods are provided in the FIS report
for this jurisdiction. The FIS report also provides instructions for determining a floodway
using non - encroachment widths for flooding sources studied by limited detailed methods.
NOTES TO USERS
Certain areas not in Special Flood Hazard Areas may be protected by flood control This map reflects more detailed and up -to -date stream channel configurations than
structures. Refer to Section 4,4 "Flood Protection Measures" of the Flood Insurance those shown on the previous FIRM for this jurisdiction. The floodplains and floodways
Study report for information on flood control structures in this jurisdiction. that were transferred from the previous FIRM may have been adjusted to conform to
these new stream channel configurations. As a result, the Flood Profiles and Floodway
Base map information a n d geospatial data used to develop t hi s F I RM were obta i ned from Data tables in the Flood I nsura n ce Study report (which h contains authoritative h dr au
lic
various organizations, including the participating local community(ies), state and federal data) may reflect stream channel distances that differ from what is shown on this map.
agencies, and /or other sources. The primary base for this FIRM is aerial imagery acquired by
Orange County. The time period of collection for the imagery is 2003. Information and Please refer to the separately printed Map Index for an overview map of the county
geospatial data supplied by the local community(ies) that met FEMA base map specifications showing the layout of map panels, community map repository addresses, and a Listing of
were considered the preferred source for development of the base map. See geospatial Communities table containing National Flood Insurance Program dates for each community
metadata for the associated digital FIRM for additional information about base map as well as a listing of the panels on which each community is located.
preparation.
If you have questions about this map, or questions concerning the National Flood
Base map features shown on this map, such as corporate limits, are based on the Insurance Program in general, please call 1- 877 -FERA MAP (1-877 -336 -2627) or visit the
most up -to -date data available at the time of publication. Changes in the corporate FEMA website at www.fema.gov,
limits may have occurred since this map was published. Map users should
consult the appropriate community official or website to verify current conditions of An accompanying Flood Insurance Study report, Letter of Map Revision (LOMR) or Letter
jurisdictional boundar i es and base map f eatures Th i s map may contain roads that were of Ma p Amendment ( L O MA ) revising P ort i ons o f th i s panel, and digital vers i ons o f this
not considered in the hydraulic analysis of streams where no new hydraulic model was FIRM may be available. Visit the North Carolina Floodplain Mapping Program website
created during the production of this statewide format FIRM. at www.ncfloodmaps.com, or contact the FEMA Map Service Center at 1,800 -358 -9616
for information on all related products associated with this FIRM. The FEMA Map Service
Center may also be reached by Fax at 1- 800 -358 -9620 and its website at www,msc,fema.gov,
i °57' 00"
3980 0O m
310 000 FE_T
MAP REPOSITORY
Refer to listing of Map Repositories on Map Index or visit www.ncfloodmaps.com.
INS CE ATE MAP
F FLOOD IN E R PANEL
EFFECTIVE DATE O LO
FEBRUARY 2,2007
EFFECTIVE DATES) OF REVISIONS) TO THIS PANEL
statewide in refer to the Community Ma
For community map revision history prior to slat mapping, ty p
History table located in the Flood Insurance Study report for this jurisdiction.
To determine if flood insurance Is available le in th i s community, contact your in sura n ce agent,
the
North Carolina Division of Emergency Management or the National Flood Insurance Program at the
following phone numbers or websites:
NC Division of Emergency Management National Flood Insurance Program
(919) 715 -8000 www.nccrimecontrol.org /nfip 1- 800 - 638 -6620 www.fema.goy/nfip
LEGEND
SPECIAL FLOOD HAZARD AREAS (SFHAs) SUBJECT TO
INUNDATION BY THE 1% ANNUAL CHANCE FLOOD
The 1 % annual chance flood (100 -year flood), also known as the base flood, is the flood
that has a 1 % chance of being equaled or exceeded in any given year. The Special
Flood Hazard Area is the area subject to flooding by the 1% annualchance flood. Areas
of Special Flood Hazard include Zones A, AE, AH, AO, AR, A99, V, and VE. The Base
Flood Elevation is the water - surface elevation of the 1% annual chance flood.
ZONE A No Base Flood Elevations determined.
ZONE AE Base Flood Elevations determined.
ZONE AH Flood depths of 1 to 3 feet (usually areas of ponding); Base Flood
Elevations determined.
ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain);
average depths determined. For areas of alluvial fan flooding, velocities
also determined.
ZONE AR Special Flood Hazard Area formerly protected from the 1% annual
chance flood by a flood control system that was subsequently
decertified. Zone AR indicates that the former flood control system is
being restored to provide protection from the 1% annual chance or
greater flood.
ZONE A99 Area to be protected from 1 % annual chance flood by a Federal
flood protection system under construction; no Base Flood Elevations
determined.
ZONE VE Coastal flood zone with velocity hazard (wave action); Base Flood Elevations
determined.
FLOODWAY AREAS IN ZONE AE
The floodway is the channel of a stream plus any adjacent floodplain areas that must be
kept free of encroachment so that the 1 % annual chance flood can be carried without
substantial increases in flood heights.
OTHER FLOOD AREAS
ZONE X Areas of 0.2% annual chance flood; areas of 1% annual chance flood
with average depths of less than 1 foot or with drainage areas less than
1 square mile; and areas protected by levees from 1 % annual chance
flood.
OTHER AREAS
ZONE X Areas determined to be outside the 0.2% annual chance floodplain.
ZONE D Areas in which flood hazards are undetermined, but possible.
® COASTAL BARRIER RESOURCES SYSTEM (CBRS) AREAS
OTHERWISE PROTECTED AREAS (OPAs)
CBRS areas and OPAs are normally located within or adjacent to Special Flood Hazard Areas.
1% annual chance floodplain boundary
0.2% annual chance floodplain boundary
— — — — Floodway boundary
Zone D Boundary
•������������������• CBRS and OPA boundary
Boundary dividing Special Flood Hazard Area Zones and
boundary dividing Special Flood Hazard Areas of different
Base Flood Elevations, flood depths or flood velocities.
_513— Base Flood Elevation line and value; elevation in feet*
(EL 987) Base Flood Elevation value where uniform within zone;
elevation in feet*
*Referenced to the North American Vertical Datum of 1988
Cross section line
23 - - - - - - 23 Transect line
97° 07' 30" , 32° 22' 30 ^ Geographic coordinates referenced to the North American
Datum of 1983 (NAD 83)
4276 000m 1000 -meter Universal Transverse Mercator grid ticks, zone 18
1 477 500 FEET 2500 -foot rid values: North Carolina State Plane coordinate
system (FIPSZONE 3200, State Plane NAD 83 feet)
BM5510 North Carolina Geodetic Survey bench mark (see explanation
X in the Datum information section of this FIRM panel).
BM5510 National Geodetic Survey bench mark (see explanation in
® the Datum Information section of this FIRM panel).
• M1.5 River Mile
4
GRID NORTH
MAP SCALE 1" = 500' (1 6,000)
250 0 Soo 1000
FEET
METERS
150 0 150 300
PANEL 9870J
FIRM
FLOOD INSURANCE RATE MAP
NORTH CAROLINA
PANEL 9870
(SEE LOCATOR DIAGRAM OR MAP INDEX FOR FIRM
PANEL LAYOUT)
CONTAINS;
COMMUNITY CID No. PANEL SUFFIX
CARRBORO, TOWN OF 370275 9870 J
CHAPEL MILL, TOWN OF 370180 9870 J
ORANGE COUNTY 370342 9870 J
Notice to User: The Map Number shown below should be used
when placing map orders: the Community Number shown
above should be used on insurance applications for the subject
community.
EFFECTIVE DATE MAP NUMBER
FEBRUARY 2, 2007 3710987000J
dsovEv e , ... .
� o
}
State of North Carolina
Federal Emergency Management Agency
o
®
O
m
O ai
®

WA TERSHED SOILS INFORMA TION
THE -EDGE
RAV -13000

THE EDGE WATERSHED SOIL INFORMATION D. PERRY, EI
RAV -13000 12/18/2013
Watershed soils from the Durham County Soil Survey
Symbol
A BBC
_ EnB
G
_eB, BeC
HrB, HrC
HwB
TaD, TaE
Name
Appling sandy loam
__ Enon loam
_
Georgevilie silt Ioam
_Herndon silt loam
_Hiwassee clay loam
Tatum Gravelly silt loam
References:
1 Soil Survey: Orange County, North Carolina
United States Department of Agriculture: Soil Conservation Service (in cooperation
with North Carolina Agriculture Experiment Station).
2 SCS TR -55
United States Department of Agriculture. Soil Conservation Service. 1986.
COVER CONDITION SCS CN - HSG B
Impervious
Open _ 61
Wooded 55
Pond � � 100
COVER CONDITION SCS CN - HSG C
Impervious 98
__- ______O_pen. 74
Wooded 70
� Pond 100
COVER CONDITION SCS CN - HSG D
Impervious 98
Open _ro 80 _
Wooded 77
Pond 100
Soil Classification
B
C
B
_ B_

•l1 IRS NIi\:

PRECIPITATION DATA
THE -EDGE
RAV -13000

From Town of Chapel Hill Design Manual (2005)
RDU, N.C. RAINFALL FREQUENCY DATA
TABLE 2 -A -2
APPENDIX 2 -A
(P. 7 of 7)
DEPTH - DURATION - FREQUENCY TABLE
Duration
Return Period
2 -Year
(inches)
5 -Year
(inches)
10 -Year
(inches)
25 -Year
(inches)
50 -Year
(inches)
100 -Year
(inches)
5 minutes
0.48
0.55
0.60
0.68
0.75
0.81
10 minutes
0.79
0.92
1.02
1.17
1.28
1.40
15 minutes
1.01
1.18
1.31
1.51
1.66
1.81
30 minutes
1.35
1.64
1.85
2.16
2.40
2.64
60 minutes
1.70
2.12
2.41
2.84
3.17
3.50
2 hours
1.91
2.40
2.74
3.23
3.61
4.00
3 hours
2.12
2.68
3.07
3.62
4.06
4.49
6 hours
2.65
3.38
3.90
4.62
5.19
5.75
12 hours
3.13
4.02
4.64
5.52
6.20
6.88
24 hours
3.60
4.65
5.38
6.41
7.21
8.00
TABLE 2 -A -3
INTENSITY - DURATION FREQUENCY DATA
Duration
Return Period
2 -Year
(in -hr)
5 -Year
(in -hr)
10 -Year
(in/hr)
25 -Year
( in/hr)
50 -Year
(in/hr)
100 -Year
(in -hr)
5 minutes
5.76
6.58
7.22
8.19
8.96
9.72
10 minutes
4.76
5.54
6.13
7.01
7.71
8.40
15 minutes
4.04
4.74
5.25
6.03
6.64
7.24
30 minutes
2.70
3.28
3.71
4.32
4.80
5.28
60 minutes
1.70
2.12
2.41
2.84
3.17
3.50
2 hours
0.95
1.20
1.37
1.62
1.81
2.00
3 hours
0.71
0.89
1.02
1.21
1.35
1.50
6 hours
0.44
0.56
0.65
0.77
0.86
0.96
12 hours
0.26
0.33
0.39
0.46
0.52
0.57
24 hours
0.15
0.19
0.22
0.27
0.30
0.33
Design Manual 26 January 2004

Precipitation Frequency Data Server
Page 1 of 3
e NOAA Atlas 14, Volume 2, Version 3
Location name: Robbins, North Carolina, US* , Coordinates: 35.5000, - 79.6000
Elevation: 468ft* j
* source: Google Maps
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAH, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS
-based point precipitation frequency estimates with 90% confidence intervals (in inches)'
Average recurrence interval (years)
Duration
1
2
5
10
25
50
�����
100
200
500
1000
0.424
0.501
0.581
0.637
0.700
0.741
0.778
0.810
0.845
0.869
5 -min
(0.386 - 0.466)
(0.457 - 0.552)
(0.529 - 0.640)
(0.579 - 0.700)
(0.632 - 0.768)
(0.668 - 0.813)
(0.698 - 0.854)
(0.723 - 0.889)
(0.747 - 0.927)
(0.762- 0.955)
10
0.677
0.801
0.930
1.02
1.12
1.18
1.24
1.28
1.34
1.37
-min
1(0.617-0.745)1(0.730-0.883)1(0.847-103)
(0.926 -112)
1 (1.01 -1.22)
1 (1.06 -1.30)
1 (1.11 -1.36)
1 (1.15 -1.41)
1 (118 -1.47)
0.846
1.01
1.18
1.29
1.41
1.50
1.56
1.62
1.68
1.72
15 -min
1(0.772-0.931)1(0,918-1.11)
1 (1.07 -1.30)
1 (117 -142)
1 (1.28 -1.55)
1 (1.35 -1.64)
1 (1.40 -1.72)
1 (1.45 -1.78)
1 (1.49 -1.85)
1 (151 -1.89)
1.16
1.39
1.67
1.87
2.09
2.25
2.39
2.52
2.68
2.78
30 -min
(1.06 -1.28)
(1.27 -1.53)
(1.52 -1.84)
(1.70 -2.05)
(1.89 -2.30)
1 (2.03 -2.47)
(2.15 -2.63)
(2.25 -2.77)
(2.37 -2.94)
(2.44 -3.06)
1.45
1.75
2.14
2-
2.79
3.05
3.30
3.54
3.84
4.06
60 -min
(1.32 -1.59)
(1.59 -1.92)
(195 -2.36)
.43
(2.21 -2.67)
(2.52 -3.06)
(2.75 -3.35)
(2.96 -3.62)
(3.16 -3.88)
(3.39 -4.22)
(3.56 -4.46)
1.71
2.07
2.57
2.94
3.41
3.76
4.11
4.44
4.87
5.20
2 -hr
(1.56 -1.90)
1 (1.88 -2.30)
1 (2.34 -2.85)
(2.66 -3.25)
(3.07 -3.76)
(3.37 -4.15)
(3.65 -4.53)
(3.92 -4.90)
(4.26 -5.38)
(4.50 -5.75)
1.82
2.21
2.75
3.16
3.70
4.12
4.53
4.95
5.51
5.95
3 -hr
(1.66 -2.01)
(2.01 -2.44)
1 (2.50 -3.04)
(2.87 -3.49)
(3.33 -4.08)
(3.69 -4.53)
(4.03 -4.98)
(4.37 -5.45)
(4.80 -6.07)
(5.12 -6.55)
2.18
2.64
3.30
3.80
4.47
5.00
5.53
6.08
6.81
7.39
6 -hr
(2.00 -2.41)
(2.42 -2.91)
1 (3.01 -3.62)
(3.45 -4.17)
(4.04 -4.89)
(4.48 -5.46)
(4.92 -6.04)
(5.35 -6.63)
(5.92 -7.44)
(6.34 -8.07)
2.60
3.14
3.94-IF
4.58
5.43
6.12
6.83
7.56
8.58
9.40
12 -hr
(2.38 -2.86)
(2.88 -3.46)
(3.59 -4.33)
(4.16 -5.02)
(4.90 -5.94)
(5.47 -6.68)
1 (6.05 -7.43)
(6.63 -8.23)
(7.39 -9.34)
(7.97 -10.2)
2.88
3.60
4.51
5.23
6.20
6.97
7.76
8.57
9.67
10.5
24 -hr
(2.77 -3.22)
(3.34 -3.89)
(418 -4.88)
(4.83 -5.65)
(5.72 -6.70)
(6.41 -7.53)
(711 -8.39)
(7.84 -9.26)
(8.81 -10.5)
(9.57 -11.4)
3.49
4.20
5.23
6.03
7.12
7.98
8.86
9.75
11.0
11.9
2 -day
(3,25-3.76)
1 (3.92 -4.53)
(4.87 -5.64)
(5.60 -6.51)
(6.59 -7.68)
(7.37 -8.61)
(8.16 -9.56)
(8.96 -10.5)
(10.0 -11.9)
(10.9 -12.9)
3.71
4.45
5.52
6.35
7.49
8.39
9.30
10.2
11.5
12.5
3 -day
(3.46 -3.98 )
(4.16 -4.79)
(5.15 -5.93)
(5.91 -6.82)
(6.95 -8.04)
(7.75 -9.01)
(8.58 -10.0)
(9.42 -11.0)
(10.5 -12.4)
(11.4 -13.5)
3.93
4.71
5.81
6.67
7.86
8.79
9.75
10.7
12.1
13.1
4 -day
(3.67 -4.21)
(4.41 -5.05)
(5.43 -6.21)
(6.22 -7.14)
(730 -841)
(8.14 -9.41)
(9.00 -10.4 )
( 9.88 -11.5 )
( 11.1 -13.0 )
(12.0-14,1)
4.51
5.38
6.55
7.48
8.76
9.77
10.8
11.9
13.3
14.5
7 -day
(4.23 -4.81)
(5.04 -5.74)
(6.13 -6.99)
(6.99 -7.98 )
(8.15 -9.34)
(9.07 -10.4)
(9.99 -11.5)
(10.9 -12.7)
(12.2 -14.3 )
(13.2 -15.5)
----]F-6.12
7.35
8.32
9.62
10.6
11.7
12.7
14.1
15.2
10 -day
(4.86 -5.47)
(5.78 -6.50)
(6.93 -7.80)
(7.84 -8.83 )
(9.04 -10.2)
(9.97 -11.3)
(10.9 -12.4)
(11.9 -13.5)
(13.1 -15.1)
(14.1 -16.3)
6.93
8.18
9.66
10.8
12.4
13.6
14.9
16.1
17.9
19.2
20 -day
(6.56-7.33)
(7.75 -8.65)
(9.14 -10.2)
(10.2 -114)
(11.7 -13.1)
(12.8 -14.4)
(14.0 -15.8)
(15.1 -17.1 )
( 16.6 -19.0 )
( 17.8 -20.4 )
8.59
10.1
11.8
13.0
16.0
17.3
18.6
20.3
21.6
30 -day
(8.17 -9.06)
(9.61 -10.6)
(11.2 -12.4)
(12.4 -13.7)
(13.9 -15.5)
(151 -16.9)
(16.3 -18.2 )
(17.5 -19.6)
(19.0 -21.5)
(20.2 -22.9)
10.9
12.8
14.6
16.0
17.8
19.2
20.6
21.9
23.7
25.0
45 -day
(10.4 -11.5)
(12.2 -13.4)
(13.9 -15.3)
(15.2 -16.8)
(16.9 -18.7)
(18.2 -20.2)
(19.5 -21.7)
(20.7 -23.1)
(22.2 -25.0)
(23.4 -26.4)
13.1
15.2
17.2
18.7
20.7
22.2
23.6
25.0
26.8
28.1
60 -day
(12.5 -13.7)
(14.5 -16.0)
(16.4 -18.0)
(17.9 -19.6)
(19.7-21.7)
(21.1-23.3)
(22.4 -24.8)
(23.7-26.3)
(25.3 -28.2 )
(26.6 -29.7)
t Pre:.n frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numrenthesis are PF estimates at lower and upper bounds of the 90 % confidence interval. The probability that precipitation frequency estimates (for a
given and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5 %. Estimates at upper bounds are not
checst probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Plea NOAA Atlas 14 document for more information.
Back to Top
PF graphical
http:// hdsc. nws. noaa. gov /hdsc /pfds /pfds _printpage.html ?lat =3 5.5000 &lon =- 79.6000 &dat... 11/22/2013

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THE EDGE PRE-DEVELOPMENT HYDROLOGY J. EASON, El
RAV-13000 Sub-basin 1 1/27/2014
t[SGy���. Impervious � Open Wooded
A
9
30
6 - 1
70 -
C
D
74
E L
98
Assume: FISGW
0%
HSG'B'=
66%
HSG'C'=
6%
HSG'D'—
28%
Cover Condition
SCS CN omia_envs_
Impervious
98
Open
_�f Assume good condition
' -- -t
Wooded
62 Assume good c on-,
d—i i—o n__
ll. PRE-DEVELOPMENT
A. Onsite Impervious Breakdown
-- Area — —
Contrsbutin Area Isfl--r­x­re -
_ __ A�eaj!c_A_"
Building
__'Farkin
5,E4 0.12
oads
Sidewalk
0 0.00
0 0.00
Other
3,580 0.08
Totals
8,604 0.20
B. Watershed Breakdown
Con rih.ti.g Area
SC'S­`CNfT'_
Area [acres
Onsite impervious
Onsite open
98 8,604
67 1 106,502
2.44
Onsite wooded
62 1 815,664
18.73
Onsite pond
100 I
0.00
FfsIte_im_p`e_r_v_ions _9_8____
_0
____
'0
Offsite open
67 45,953
1.
afTS—Ite w­oo­de_d_"­_
62 112,801
2.59
Offsite pond 1
106 0
0.00
Total area = 25.01 acres
0.0391 sq.ini.
Composite SCS CN = 63
o/6 Impervious = 0.8%
Assume good condition
Assume stood condition
Assume good condition
Assurne good condition

THE EDGE PRE - DEVELOPMENT HYDROLOGY J. EASON, Et
RAV -13000 Sub -basin 1 1/27/2014
C. Time of Concentration Information
Tinge of concentration is calculated using the SCS Seginenial Approach ('1R -55)
Segment 1: Overland Flow
Length =
Length =
100
ft
Height =
2.5
ft
Slope =
0.0250
ft/ft
Manning's n =
0.40
wooded - light underbrush
P (2- year /24 -hour) =
3.5
inches (Chapel Hill, NC)
Segment Time =
18.78
minutes
Segment 3: Channel Flow
Length =
Length =
715
ft
Height -
23
ft
Slope =
0.0322
ft /ft
Manning's n =
0.045
natural channel
Flow Area =
4.00
sf (assume 2' x 2' channel)
Wetted Perimeter =
4.00
if (assume 2'x T channel)
Channel Velocity =
5.94
ft /sec
Segment Tinge =
2.01
minutes
Segment 2: Concentrated Flow
Length =
913
ft
Height =
46.5
ft
Slope =
0.0509
ft/ft
Paved ? =
No
Velocity =
3.64
ft /sec
Segment Tinge =
4.18
minutes
Segment 3: Channel Flow
Length =
320
ft
Height =
9.5
ft
Slope =
0.0297
ft/ft
Manning's a =
0.045
natural channel
Flow Area =
9.00
sf (assume 2'x 2' channel)
Wetted Perimeter =
9.00
if (assume 2'x T channel)
Channel Velocity =
5.71
ft /sec
Segment Time =
0.93
minutes
Time of Concentration = 24.97 minutes
SCS Lag Time = 14.98 minutes (SCS Lag = 0.6* Tc)
Time Increment = 4.34 minutes (= 0.29 *SCS Lag)
[it. 2 -YEAR RUN -OFF VOLUME CALCULATIONS
Pre development rmtoff volume calculations are based upon the SCSMethod. The equation .for this method is as follows:
Q* = ((P- 0.2 *S)') / (P +0.8 *S)
where,
O* = Direct R:utoff /inches]
S = Potential Abstraction => (1000: SCS Curve Number) -10
P = Accumulated Storm Rainfall [inches]
Per Town ofChapel Hill ordinance requirements, the increase in volume between pre- and pos7- development for the 2-year
24 -hour storm shall be heated within the proposed stwomwater management facility.
On -Site Area = 21.37 acres
On -site SCS CN = 63
S = 5.88
P (2 -yr / 24 -hour) = 3.60 inches
Q* = 0.71 inches
On site Run -off Volume = 1.26 acre -feet
54871 of

THE EDGE PRE- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 2 1/27/2014
I. SCS CURVE NUMBERS
P HSGT Impervious Open Wooded
A 98 39 30
B 98 61 55
C 98 74 70
77
Assume: HSG'A'= 0%
[ISG'B'= 74%
HSG'C'= 0%
HSG 'D' = 26%
Cover Condition SCS CN ( Comments
_Impervious 98 . m
Open 66 Assume good condition
su
Wooded j 61 Asme good condition _.
II. PRE' -DEVELOPMENT'
A. Onsite Impervious Breakdown
Contributing Area Area jsfJ Area acres
Building „ 0 0.00
Parking/Roads 0 0.00
Sidewalk 0 0.00_
Other _ _ 246 0.01
b TotalsAO, �..a.,. ,.2466 0.01
B. Watershed Breakdown
Contributing Area SCS CN Area Isf] Area jaci
Onsite impervious 98 0 0.00
Onsite open 66 7,556 0.17
Onsite wooded 61 70,461 1.62
_._
Onsite pond _ 1.00_..__ 0_ _.._..0.00
Offsite impervious 98 14,869 0.34
_ Offsite open 66 83,450 _1.92
O_ffsite_wooded61_ 622,414 14.29
Offsite pond 100 _ _. - ._ - - -. 0.0 0
Total area = 18.34 acres
0.0287 sq.mi.
Composite SCS CN = 62
Impervious = 1.9%
wComments .
Assume good condition
Assume good condition
Assume good condition
Assume good condition

THE EDGE PRE- DEVELOPMENT HYDROLOGY J. EASON, E1
RAV -13000 Sub -basin 2 1/27/2014
C. Time of Concentration Information
Time of concentration is calculated using the SCS Segmental Approach ('TR -55).
Segment 1: Overland Flow
Length =
Height =
Slope =
Manning's n =
P (2- year /24- hour)=
Segment Time =
Segment 3: Channel Flow
Length =
Height =
Slope =
Manning's n =
Plow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
100
ft
3.5
ft
0.0350
ft/ft
0.40
wooded - light underbrush
3.6
inches (Chapel Hill, NC)
16.10
minutes
999
ft
17.5
ft
0.0175
ft /ft
0.045
natural channel
9.00
sf (assume 3' x 3' channel)
9.00
if (assume 3' x 3' channel)
4.38
ft/see
3.80
minutes
Segment 2: Concentrated Flow
6.33
Length =
590
ft
Height=
33
ft
Slope =
0.0559
ft /ft
Paved ? =
No
4085
Velocity=
3.82
ft/sec
Segment Time =
2.5E
minutes
Time of Concentration = 22.56 minutes
SCS Lag Time = 13.54 minutes (SCS Lag = 0.6* Tc)
Time Increment = 3.93 minutes (= 0.29 *SCS Lag)
III. 2 -YEAR RUN -OFF VOLUME CALCULATIONS
Pre - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q" = ((P- 0.2.S)2)/ (P +0.8*S)
where,
0* = Direct Runoff[inches]
S = Potential Abstraction => (1000 / SCS Curve Number) - 10
P = Accumulated Storm Rainfall [inches]
Per Town of Chapel Hill ordinance requirements, the increase in volume between pre- and post- development for the 2-y ar
24 -hour storm shall be treated within the proposed stormwater management facility.
On -Site Area = 1.79 acres
On -site SCS CN = 61
S=
6.33
P (2 -yr / 24 -hour) =
160
inches
Q* =
0.63
inches
1 On -site Run -off Volume =
0.09
acre -feet
=
4085
cf

THE EDGE PRE- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 1/27/2014
I. SCS CURVE NUMBERS
HSG
A
Area [sfJ Area jacresl
Impervious
98
Open Wooded
39 30_
B
6,874
98
_
61 55
C
98
74 70
D
Sidewalk
98:.._..�,a.. _ c_80 0.,.... 77�...m
Assume:
HSG'A' =
0%
Other
HSG'B'=
87%
Totals
HSG'C'=
13%
0.40
HSG'D'=
0%
over Condition
SCS CN
Comments
hnperv�ous
�
98
��
Open
0.40
63
Assume good condition
Wooded I
57
Assume good condition
II. PRE - DEVELOPMENT
57
100
832,509
0
A. Onsite Impervious Breakdown
Contributing Area F
Area [sfJ Area jacresl
Buildin
6,874
0.16
Parking /Roads
1,035
0.02
Sidewalk
0
0.00
Other
9,713 i_
0.22
Totals
17,622,
0.40
B. Watershed Breakdown
Contributing Area
SCS CN
Area �sf� Arca jac
Onsite impervious
98
17,622
0.40
Onsite open
63 i
i
39,886
0.92
Onsite wooded
Onsite pond
57
100
832,509
0
19.11
0.00
Offsde impervious
i 98
____ . _ _
88,148
2.02
Offsite Subdivision
68
45,456
104
Offsde open
63
274,603 t
6_30
Offsite wooded
�0ffsite-
57 j
53 725
�j
1.23
pond
100 {
0
0.00
Total area = 31.04 acres
0.0485 sq.mi.
Composite SCS CN = 62
Assume good condition
Assume good condition
TR 55 CN for I acre Residential lots
Assume good condition
Assume good condition
% Impervious = 8.5% * *Includes 20% impervious from Subdivision area.

THE EDGE PRE - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 1/27/2014
C. Time of Concentration Information
Time of concentration is calculated using the SCS Segmental Approach (TR -55).
Segment I: Overland Flow
Length =
Height =
Slope =
Manning's n =
P (2- year /24 -hour) _
Segment Time =
Segment 3: Channel Flow
Length
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter =
Channel Velocity =
Segment Time =
100
ft
2
ft
0.0200
ft /ft
0.40
wooded - light underbrush
3.6
inches (Chapel Hill, NC)
20.25
minutes
801
ft
12.5
ft
0.0156
ft /ft
0.045
natural channel
9.00
sf (assume 3' x 3' channel)
9.00
if (assume 3' x 3' channel)
4.14
ft /sec
3.23
minutes
Segment 2: Concentrated Flow
Length =
1183
ft
Height=
44.5
ft
Slope =
0.0376
ft /ft
Paved ? =
No
acre -feet
Velocity =
3.13
ft /sec
Segment Time =
0.30
minutes
Time of Concentration = 29.77 minutes
SCS Lag Time = 17.86 minutes (SCS Lag = 0.6* Tc)
Time Increment = 5.18 minutes (= 0.29 *SCS Lag)
III. 2 -YEAR RUN -OFF VOLUME CALCULATIONS
Pre - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q* = ((P- 0.2 *S)2) / (P +0.8 *S)
where,
Q * = Direct Runoff [inches]
S = Potential Abstraction => (1000 / SCS Curve Number) - 10
P = Accumulated Storm Rainfall [inches]
Per Town of Chapel Hill ordinance requirements, the increase in volume between pre- and post- development for the 2-year
24-hour storm shall be treated within the proposed stornnmater nuanagernent facility.
On -Site Area = 20.43 acres
On -site SCS CN = 58
S=
7.17
P (2-yr / 24-hour) =
3.60
inches
Q*_
0.50
inches
On -site Run -off Volume =
0.85
acre -feet
=
37227
of

THE EDGE PRE - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 4 1/27/2014
1. SCS CURVE NUMBERS
HSG Impervious Open Wooded
_
A 98 39� 30
B 98 61 55
C 98 � 74 70
9ssume: HSG'A'= 0%
HSG'B' = 92%
HSG'C'= 8%
HSG D' = 0%
Cover Condition SCS CN Comments
Impervious
Open 62 Assume good condition
Wooded 56 Assume good condition
II. PRE - DEVELOPMENT
A. Onsite Impervious Breakdown
�ContributingAreaArea [sfJj Area nacres]
Building 0 0.00
Parking/Roads 0 0.00
Sidewalk 0 0.00
Other ff 0 0.00
Totals 0 i 0.00
B. Watershed Breakdown
mn. emu, ecmmm�+maomewnmxucwzm_s.atwvvr mss- awlv�ro�mcx +vsmu�wmnrumre- m�mvmesr�.� raormcemm rmvro.
Contributing Area SCS CN ( Ai ea �sfl I Area nacres Comments
Onsite impervious 98 0 0.00
Onsrte open 62 Assume good condition
Onsite wooded 56 0 0.00 Assume good - ---- --
Onsite pond 100 1 0 _ 0.00
Offsite io
impervus 98 0 00
Offsite Subdivision 68 690,852 15.86 mm TR 55 CN for 1 acre Residential lots
Offsite wooded 56 58,852 03 2 30 Assume good condition
Offsite open m 6?._._._._. 100_..
� 1 35 Assume good condition
_ .. _ _ _ ..
Total area = 21.13 acres
0.0330 sq.mi.
Composite SCS CN = 69
% Impervious = 15.0% * *Includes 20% impervious from Subdivision area.

THE EDGE PRE- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 4 1/27/2014
C. Time of Concentration Information
Time of concentration is calculated using the SCS Segmental Approach (TR -SS).
Segment 1: Overland Flow
Segment 2: Concentrated Flow
Length =
100
ft
Length =
864
ft
Height =
5.5
ft
Height =
31.5
ft
Slope =
0.0550
ft /ft
Slope =
0.0365
ft /ft
Manning's n =
0.40
wooded - light underbrush
Paved ? =
No
P (2- year /24 -hour) =
3.6
inches (Chapel Hill, NC)
Velocity =
3.08
ft /sec
Segment Time =
13.51
minutes
Segment Time =
4.67
minutes
Time of Concentration = 18.18 minutes
SCS Lag Time = 10.91 minutes (SCS Lag = 0.6" Te)
Time Increment = 3.16 minutes (= 0.29*SCS Lag)

THE EDGE PRE - DEVELOPMENT HYDROLOGY
RAV -13000 Sub -basin Unanalyzed
I. SCS CURVE NUMBERS
HSG Impervious Open Woode
A 98 39 30
98 _ ... _ 55
C
_._ C_._ __. 98 80 � 77_
Assume: HSG 'A' = 0%
HSG 'B' = 74%
HSG 'C' = 0%
HSG'D'= 26%
Cover Condition SCS CN CoInments
__._.._ Impervious
m _.w 98
Open 66 Assume good condition
p�F ,Wooded 61 Assume good condition
II. PRE- DEVELOPMENT
A. Onsite Impervious Breakdown
Contributing Area Area [sff i Area facresL L
.M.. _
Building m . _ _ 0 ._ 0.00
Parkin Roads 0 0.00
Sidewalk 0 _0.00
Other 7,554 __. 0.17
Totals 7,554 0.17
B. Watershed Breakdown
Contributing Area SCS CN s a jac
Onsite impervious i 98 _7_554 0.17
Onsite op en _ 75,118_ �� 1 72
Onsite wooded 61 241,361 5.54
N_ _ .m
Onsite pond v 100 0 0.00
Offsite impervious-,­­ 98 0 0.00
Offsite open �. ((" -. 0.00
Offsite wooded �61 0 0.00
Offsite pond .� 100 a ...� 0.00
Total area = 7.44 acres
0.0116 sq.mi.
Composite SCS CN = 63
% Impervious = 2.3%
Comments-
Assume good condition
Assume good condition
Assume good condition
Assume good condition
J. EASON, El
1/27/2014

THE EDGE PRE - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin Unanalyzed 1/27/2014
1II. 2 -YEAR RUN -OFF VOLUME CALCULATIONS
Pre - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q* = ((P-0.2 S)2)/ (P +0.8 -S)
where,
Q* = Direct Runoff [inches]
S = Potential Abstraction —> (1000 /SCS Curve Number) - 10
P = Accumulated Storm Rainfall [inches]
Per Town of Chapel Hill ordinance requirements, the increase in volume between pre- and post- development for the 2-year
24 -hour storm shall be treated within the proposed stormwater management facility.
On -Site Area = -
7.44 acres
On -site SCS CN =
63
S =
5.92
P (2 -yr / 24 -hour) =
3.60 inches
Qx =
0.70 inches
On -site Run -off Volume = 0.43 acre -feet
= 18889 cf

THE EDGE PRE- DEVELOPMENT HYDROLOGY J. EASON, El
PAV -13000 Reach Data 1/27/2014
lit. REACH DATA
REACH #1 - POA 2 TO POA 1
Time of concentration is calculated etsing the SCS Segrental Approach (772 -55)
.5'egment 1: Channel Flow
Length =
62
ft
Height=
1
ft
Slope =
0.0161
Wilt
Manning's n =
0.045
natural channel
Flow Area =
9.00
sf (assume 3' x 3' channel)
Wetted Perimeter =
9.00
if (assume 3' x 3' channel)
Channel Velocity =
4.21
ft/sec
3egrnent Time =
0.25
minutes
Segment 1: Channel Flow
Length =
320
ft
Height=
9.5
ft
Slope =
0.0297
ft /ft
Manning's n =
0.045
natural channel
Flow Area =
9.00
sf (assume 3' x 3' channel)
Wetted Perimeter=
9.00
If (assume 3' x 3' channel)
Channel Velocity =
5.71
ft/sec
Segment Time =
0193
minutes
Time of Concentration = 1.18 minutes
SCS Lag Time = 0.71 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.21 minutes (= 0.29 *SCS Lag)
REACH 92 - POA 3 TO POA 2
Tune ofconcentration is calculated using the
SCSSegmental
Approach (17?-55).
Segment 1: Channel Flow
17.5
It
Length =
564
ft
Height =
12.5
It
Slope =
0.0222
ft /ft
Manning's u =
0.045
natural channel
Flow Area =
9.00
sf (assume 3' x 3' channel)
Wetted Perimeter=
9.00
If (assume 3' x 3' channel)
Channel Velocity =
4.93
ft /sec
Segment Time =
1.91
minutes
Segment 2: Channel Flow
Length =
999
It
Height =
17.5
It
Slope =
0.0175
ft /ft
Manning's n =
0.045
natural channel
Flow Area =
9.00
sf (assume 3' x 3' channel)
Wetted Perimeter =
9.00
If (assume 3' x 3' channel)
Channel Velocity =
4.38
ft /sec
Segment Tinte =
3.80
minates
Time of Concentration = 5.71 minutes
SCS Lag Time = 3.42 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.99 minutes = 0.29 *SCS Lag)
REACH #3 - POA 4 TO POA 3
Time of concentration is calculated using the
SCS Segmental Approach (TR -55).
.5'egment 1: Channel Flow
Height =
14.5
Length =
801
ft
Height =
12.5
It
Slope =
0.0156
ft/ft
Manning's n =
0.045
natural channel
Flow Area =
9.00
sf (assume 3' x 3' channel)
Wetted Perimeter =
9.00
If (assume 3' x T channel)
Channel Velocity =
4.14
ft/sec
Segntertt Time =
3.23
minutes
Time of Concentration = 3.23 minutes
SCS Lag Time = 1.94 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.56 minutes = 0.29 *SCS La
REACH #4 - SUB -BASIN 4 TO POA 4
Time ofconcentration is calculated using the
SCS Segmental Approach (77?-55).
Segment 1: Pipe Flow
Height =
14.5
Length =
67
ft
Height=
2
ft
Slope =
0.0299
ft/ft
Manning's n =
0.013
Concrete Pipe
P (2- year /24 -hour) =
3.6
inches (Chapel Hill, NC)
Segment Time =
A81
minutes
.5'egntent 2: Channel Flow
Length =
398
ft
Height =
14.5
ft
Slope =
0.0364
fVft
Manning's n =
0.045
natural channel
Flow Area =
4.00
sf (assume 3' x 3' channel)
Wetted Perimeter =
4.00
If (assume 3' x 3' channel)
Channel Velocity =
6.32
ft/sec
Segment Tinte =
1.05
minutes
Time of Concentration = 1.86 minutes
SCS Lag Time = 1.11 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.32 minutes (= 0.29 *SCS Lag)

'J MCADAMS
Scenario: Pre - Development
THE EDGE J. EASON, El
RAV 13000. p pc 1/23/2014

9 M.C:11DAMS
Subsection: Master Network Summary
Catchments Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ac -ft)
Sub 1
Pre 1 Year
1
0.876
739.00
6.04
Sub 1
Pre 2 Year
2
1.464
736.00
12.02
Sub 1
Pre 25 Year
25
5.106
736.00
46.18
Sub 2
Pre 1 Year
1
0.591
737.00
4.03
Sub 2
Pre 2 Year
2
1.004
737.00
8.46
Sub 2
Pre 25 Year
25
3.607
734.00
34.41
Sub 3
Pre 1 Year
1
0.997
746.00
6.05
Sub 3
Pre 2 Year
2
1.696
742.00
12.22
Sub 3
Pre 25 Year
25
6.091
739.00
49.74
Sub 4
Pre 1 Year
1
1.153
732.00
12.52
Sub 4
Pre 2 Year
2
1.776
732.00
20.68
Sub 4
Pre 25 Year
1 25
1 5.321
730.00
58.54
Node Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ac -ft)
POA 1
Pre 1 Year
1
3.607
744.00
27.21
POA 1
Pre 2 Year
2
5.926
742.00
50.17
POA 1
Pre 25 Year
25
20.087
741.00
176.66
POA 2
Pre 1 Year
1
2.732
743.00
21.37
POA 2
Pre 2 Year
2
4.464
743.00
39.29
POA 2
Pre 25 Year
25
14.987
741.00
135.27
POA 3
Pre 1 Year
1
2.148
738.00
17.57
POA 3
Pre 2 Year
2
3.468
737.00
32.01
POA 3
Pre 25 Year
25
11.404
737.00
106.80
POA 4
Pre 1 Year
1
1.152
734.00
12.52
POA 4
Pre 2 Year
2
1.775
734.00
20.68
POA 4
Pre 25 Year
25
5.318
732.00
58.54
Sub -4o
Pre 1 Year
1
1.153
732.00
12.52
Sub -4o
Pre 2 Year
2
1.776
732.00
20.68
Sub -4o
Pre 25 Year
1 25
1 5.321
1 730.00
1 58.54
THE EDGE J. EASON, El
RAV13000.ppc 1/27/2014

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PROJECT N0. RAV -13000
FILENAME: RAV13000 —PRE
DESIGNED BY:
DRAWN BY: JLE
SCALE: 1"=150'
DATE: 04-10-2014
SHEET NO. PRE
�.J MCADAMS

POST - DEVELOPMENT HYDROLOGIC
CALCULATIONS
THE -EDGE
RAV -13000

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THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON. El
RAV -13000 Sub -basin ]-Bypass 5/23/2014
1. SCS CURVE NUMBERS
HSG Impervious
Open
Wooded
A 98
39
30
B 98
61
55
.— C 98
74
70�
98
80
Assume: HSG'A'= 0%
HSG'B'= 66%
HSG'C'= 6%
HSG'D'= 28%
Cover Condition �� SCS CN
�. � Comments
_
Omen 67
Assume good
condition
mm � Wooded � �62 �
Assume good
condition
A. Onsite Impervious Breakdown
Com[ ibuting Area Neas Area jsfJ
0
Block
G Dereloable 0 � 0.00
Nen.crund Ares 0 _• 0.00
% Imp Imp Area
Im p Area sf acres
0.00
0
0 1 0.
B. Onsite Open Space Breakdown
Contributing Area Meas Area lsf� % Open Open Area Is Open Aren q
e acres
ROW Areas 0 10% 0 _0.00_
Connneroial Areas 0 _ _ 20% 0
Mama ed Pervious ._ 61,316__ 100% 61316 1.41_
�- st SQ093 100% - _ 50,093 1.15n
Tool Measured Area 111.409 t11,409 2.56
C. Watershed Breakdown
. F Contributing Area SCS CN Area [sfl Area lacres Comments
Onsite i_mpercious 98 _ 0 _ 0.00�,�_
LL Onsite open__ _. w67 _ 61316 _ 1.41_ Assume good condition
Onsite wooded 62 50.093 1.15 Assume og od condition
n.1aenend _ ion — — - - -- o.00 il _ —.
Offsite omen
ilTsite wooded__ __62
OITsite�ond��w, ,, ,•V100
Total Sub -basin Area =
Composite SCS CN =
% Impervious =
13.594_ 0.31
7310 0.17
0 _ 000
3.04 acres
09047 sq.mi.
65
0.0%

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV-13000 Sub - basin 1- Bypass 5/23/2014
D. Time of Concentration iiifm,maton
Tome ofconcena ation is calculated using the SC'S Sagmentol Approach (1R -55).
Segment 1: Overland F1
Segment 2: Concentrated
Moir
Length =
Length =
100
It
Length ==
263
ft
Height=
1.5
ft
Height=
26.5
ft
Slope=
0.0150
fit/fit
Slope=
0.1008
ft/ft
Manning's n =
0.40
Wooded - light underbrush
Paced'i =
No
P (2- pear /24 -hour) =
3.6
inches (Chapel Hill. NC)
Velocilc =
5.12
n /sec
.Segu+eut Time =
22.71
minutes
Segment Time =
0.86
mluutes
Seguneul 3: Channel Florw
Length =
251
ft
Height =
8.5
0
Slope=
0.0339
ft/ft
Manning's n =
0.045
natural channel
Flout Area=
9.00
sf (assume 3' x T charnel)
Wetted Perimeter =
9.00
If (assume 3' s Y channel)
Channel Velocih =
6.09
ft/sec
.Segment 77 n+e=
0.69
suiuutea
Time of Concentration =
24.26
minutes
SCS Lag Time =
14.55
minutes (SCS Lag = 0.6* Tc)
Time Increment =
422
minutes (= 0.29 "SCS Lag)
Ill. POST - DEVELOPMENT RUN-OFF VOLUME CALCULATIONS
Post - development iu f(volume calculations are based upon the SCS Method. The equanon for this method is as follows
Q* = ((P- 0.2 *S)')/ (P +0.8 *S)
NOiere.
O" = Direct Runo(f[aiches]
S = Potential Abstraction => (1000. SCS Curve Numbet) - 10
1' — Accumulated Storm Rainfall /inches)
Per Town of(hapel Hill ordinance requirements- the increase in volume benveen pre- and post - development for the 2,vear
24 -hour storm shah be treated within the proposed stormwatcr management facility
__> Post - development 2 -Year Runoff I olu ie Calculations
On -Site Area = 2.56 acres
On -site SCS CN = 65
S= 542
P (2 -pr / 24 -hour) = 3.60 inches
Q. = 0.80 inches
On -site Run -off Volume = 0.17 acre-feet
7398 cf

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 1 -To SWMF 1 5/23/2014
HSG
Impervious '
Opcn
Wooded
A
98
39
30
Onsite open
67
59,269
1.36
Assume_�ood condition
98
74
70 m.m
D
98 _._.
80
77
Assume: HSG'A'=
0%
HSG'B'=
66%
HSG'C'
= 6%
HSG'D'=
28%
, n
Condition
SCS CN�
Comments
_Cover
Impervious
Assume good condition
_
Open
67
Assume food condition —_
Wooded
62
Assume good condition
A. Onsite Impervious Breakdown
Meas Area
Contributing Area Meas Area [sfJ 'Yo Imp Imp Area [sfl Imp Area
[acres] acres
_ ROW Areas 0 0.00 90% 0 0.00
�Block ADevelopable 0 0.00� 80% _ 0 _ 0.00_
_.._yBloc_kB 0_._O.00w�80% 0 0.00
_.._.. _._ Block _C _ 0 _m 0.00 � 80 %� __.._..0 0.00
Block _Block D Developable 0 _ 0.00 80% 0 0.00
Block _E _ 0 .. _. 0.00 _80 %_ _ 0 0.00_
Block F _ 0 0.00 _80% 0 0.00
_ _ Block G Develo able 214,729 4.93 80% _ 171,7833 94
Total Measured Area 214,729 4.93 171,783 3.94
B. Onsite Open Space Breakdown
Contributing Area Meas Area Isfl 'Yo Open Open Area jsfl Open Area
acres
ROW Areas 0 10% 0 0.00
Commercial Areas 214,729 20% 42,946 0.99
Managed Pervious 16,323 100% 16,323 0.37
__.. Forest __. 0 100% � O0.00
C. Watershed Breakdown
Contributin Area
SCS CN Area sf Area acres
Comments
Onsite impervious _
98
Onsite open
67
59,269
1.36
Assume_�ood condition
Onsite wooded
62
0
0.00
Assume food condition
Onsite pond ___„ ._
100
10_,949
0.25
0.00
_
Offsitee impervious
98
0�
Offsite open
67
0
0.00
Assume good condition
mm
Offsite wooded
62
0
0.00
Assumeood condition
Offsrte and
100m
0 _j
0.00
w
Total Sub -basin Area =
5.56
acres
0.0087
sq.mi.
Composite SCS CN =
91
Impervious =
71.0%

THE EDGE POST- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin I -To SWMF 1 5/23/2014
D. Time of Concentration Information
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)
Time Increment = 0.87 minutes (= 0.29 *SCS Lag)
M. POST - DEVELOPMENT RUN OFF VOLUME CALC[s"LATIQNS _
Post -deve .
lopmeru runoffvohnne calculations are based upon the SCSMetlaod. 1lze egzariion for this method is as follows:
Q* = ((P- 0.2 *S)z) / (P +0.8 *S)
where,
Q* = Direct RunoffI inches I
S = Potential Abstraction => (1000 -' SCS Curve Nwnber) - 10
P - Accumulated Storm Rainfall [inches)
Per "Town of Chapel Hill ordinance requirements, the increase in volume between pre- and post - development for I 2 -year
24-hour storm shall be treated within the proposed stornzwater managenzent.facility.
=> Post - development 2 -Year Runoff Volume Calculations
On -Site Area = 5.56 acres
On -site SCS CN = 91
S = 1.05
P (2 -yr / 24 -hour) = 3.60 inches
Q*_ 2.59 inches
On -site Run -off Volume = 1.20 acre -feet
52245 of

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 1 -To SWMF2 5/23/2014
L SCS CURVE NUMBERS
Assume:
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
HSG'A'= 0%
HSG'B'= 66%
HSG'C'= 6%
HSG'D'= 28%
Cover Condition
SCS CN
Comments
Impervious
98
Imp Area
acres
Open
67
Assume good condition
Wooded
62
Assume good condition
I1. POST - DEVELOPMENT
A. Onsite Impervious Breakdown
Contributing Area
Meas Area [sf[
Meas Area
acres
% Imp
Imp Area [sfl
Imp Area
acres
ROW Areas
89,241
2.05
90%
80,317
1.84
Block A Develo able
0
0.00
80%
0
0.00
Block B
0
0.00
80%
0
0.00
Block C
0
0.00
80%
0
0.00
Block D Developable
0
1 0.00
80%
0
0.00
Block E
236,575
5.43
80%
189,260
4.34
Block F
265,690
6.10
80%
212,552
4.88
Block G Developable
60,915
1.40
80%
48,732
1.12
Total Measured Area
652,421
14.98
530,861
12.19
B. Onsite Open Space Breakdown
Contributing Area
Meas Area [sff
% Open
Open Area [sfJ
Open Area
acres
ROW Areas
89,241
10%
8,924
0.20
Commercial Areas
563,180
20%
112,636
2.59
Managed Pervious
41,599
100%
41,599
0.95
Forest
0
100%
0
0.00
Total Measured Area
1 694,020
4,319
1 163,159
1 3.75
C. Watershed Breakdown
Contributing Area
SCS CN
Area Isfl
Area jacresl
Comments
Onsite impervious
98
530,861
12.19
Onsite open
67
163,159
3.75
Assume good condition
Onsite wooded
62
0
0.00
Assume good condition
Onsite pond
100
33,542
0.77
Offsite impervious
98
4,319
0.10
Offsite o en
67
4,579
0.11
Assume good condition
Offsite wooded
66
97,578
2.24
Assume good condition
Offsite pond
100
0
0.00
Total Sub -basin Area =
19.15 acres
0.0299 sq.mi.
Composite SCS CN =
88
% Impervious =
64.2%

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 1 -To SWMF2 5/23/2014
D. Time of Concentration Information
Titre of concentration is assumed to be .i minutes.
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.87 minutes (= 0.29 *SCS Lag)
Ili. POSTLLDEirLLOPIVltE iT ;RUB- OPFVOLUIVtE,CALCULATIONS
Post - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q* = ((P- 0.2 *S)2) / (P +0.8 *S)
where,
Q* = Direct Runglf(inchesJ
S == Potential Abstraction => (1000! SCS Curve Number) -10
P = Accumulated Sto-m Rainfall /inches/
Per Town of Chapel Hill ordinance requirements, the increase in volume between pre - and post - development for the 2 -year
24-hour storm shall be treated within the proposed stormwater management facility.
= => Post - development 2 -Year Runoff !Volume Calculations
On -Site Area = 16.70 acres
On -site SCS CN = 91
S_ 0.97
P (2 -yr / 24 -hour) = 3.60 inches
Q*_ 2.65 inches
On -site Run -off Volume= 3.69 acre -feet
160761 of

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, EI
RAV -13000 Sub -basin 2- Bypass 5/23/2014
HSG
B
Impervious
98
Open Wooded
61 55
..._._— .._.�.._D
98
Asaunre: HSG'A'= 0%
HSG'B' = 74%
HSG'C'= 0%
HSG'D'= 26X.
_Covet• Condition SCS CN Comments
-
_Ogeu (6 Assume oog d condition
Assume good condition
A. Onsite Impmrvious Breakdown
Meas Aren
Contributing Area Meas Area IsfJ ..e %Imp Imp Area jsTJ
Block A Developable 0 0. )0 80% 0 _ 0.00
_Block B �_ _ ��- 0 O.OU 80 % (l 0.00
_Block C 0 0.00_ _80 %_ _ 0 _ 0.(10 _
- Block D Develo abler 0 _ 0.00 _ 80% _ 0
__ Block E _0_ 0.00 80% 0 0.00
Block F _ 0 0.00 _ 80% _ 000 . -.-
Block G Developable 0 _ 0.00 RO % _ _0 _ 0.00
%'olnl Measured Aren �. 0.,,,...,.,»_. ......,.... 0.00 ._k.....0._- ..�.,.... .0.00. „,.,,._...,1
B. Onsite Open Space Breakdown
Contributing Area s Meas Area jsf] % Open Open Area s Open Area
_ _ _ m acres •,
_ ROW Areas 0 mm 10
_ _ Commercial Areas _ 0� 20% 0 _0.00
Managed Pervious 4,481 100 % 4 481 _ 0.10
-Total Ale nsm.ed Aren 4,481 4,481 0.10 „
C. Watershed Breakdown
�Contributin Area SCS CN Areas Aren ac •es Comments
Onsite unpm ions 98 0 0.00 -
_ Onsiteopen w G6 4-481 _0.10 _ Assume oos�con,dition_
_.__ Onsite wooded �61 0y 0_._00 �Assume�eood condition
..T - -F— .._ �........._._..._.__. __..__
Onsite op nd_ 100 0 _ 0.00
Offsile impen•ions 98 _ 14,869 0.34 -
Offsite o en 6G 83,451 1.92 Assume 4a od condition
Offsae wooded C+l 620. )71_ 14.26 good condition
�Offsitond 100 0.00,
Total Sub -basin Area = 16.62 acres
0.0260 sq.mi.
Composite SCS CN = 62
% Impervious = 2,1%

THE EDGE POST - DEVELOPMENT HYDROLOGY I EASON. El
RAV -13000 Sub - basin 2- Bypass 5/23/2014
D. Time of Concentration Information
lime gfconcentra /ion is calculated using the SCS Segnenml Approach ( /72S5J_
.4egereut 1: Overlmnl Flow
.Segment 2: Concentrated
Flnro
1096
Length =
100
ft
Length =
323
fl
Height=
3
fl
Height=
26
ft
Slope=
0.0300
ft/fl
Slope=
0.0805
ft/fl
Manning's n =
0.40
wooded - light underbrush
Paved? =
No
4.47
P (2- year /24- hour) =
3,6
inches (Chapel Hill, NC)
Velocity =
4.58
fl/sec
Segment Tin, =
I Z21
urimrtes
Segment liar, =
1.18
oinntes
Segurent 3: Chnrmel FImP
Length =
1096
R
Height =
20
fl
Slope=
0.0182
Wit
Manning's n =
0.045
natural channel
Flory Area=
9.00
sf (assume 3' z 3' channel)
Welted Perimeter =
9.00
If (assume Tx Y channel)
Channel Velocity-
4.47
fl/sec
.S'egmeut Tiure =
4.08
minutes
Time
of Cocenhmtior= 22.47
minutes
SCS Lag Time = 13.48
minutes (SCS Lag = 0.6* Tc)
Time I-rement= 3.91
minutes (= 0.29 *SCS Lag)
Ill. l POST - DEVELOPMENT RUN -OFF VOLUME CALCULATIONS
Post development runoff vohane calculations are based upon the SCS Method The equation for this method is as follows
Q* = ((P -0.2* S)'') / (P +O.S *S)
where,
O* = Direct RunofQnches]
S = Potential Abstraction => 0000: SCS Curve Number) - 10
P = Accumulated Siorm Rainfall [inches/
Per Town Q/ Hill ordinance requirements, the increase un volume beneeen pr- and po.sl- development for the 2 -year
24 -hour storm shall be treated within the proposed siormwater management facility.
__> Pos[- derelnpuunt 2 -Yen. Rruuiff Vol C'nlculntions
On -Site Area = 0.10 acres
On -site SCS CN = 66
S= 5A7
P (2,r / 24 -hour) = 3.60 inches
Q. = 0.85 inches
On -site Run -off Volume = 0.01 acre -feet
318 cf

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, EI
RAV -13000 Sub -basin 3- 13ypass 5/23/2014
T. SCS CttRVE NUMBERS
HSG
Impervious.
Open
Wooded
A
98.
..
30
B
98
_39
61
55_
µ
.. D
98 —
80
77
Assruue: HSG'A'= 0%
HSG'B'= 87%
HSG'C'= 13%
HSG D' = 0%
ver Condition . SCS CN Comments
Co
—_ tm e�rvious 98 .,..,,...._..,.,,.,.,
Olen 63�� @Assume _good condition_ _._
Wooded —57 Assume good condition
It.. POST - DEVELOPMENT
A. Onsite Impervious Breakdown
P"Uo 90% s Arca Imp Arc
Contributing Area Meas Area jsf % [nip Imp Area (sfJ acresL ,.� .m�a..�Ie.;,� ROW Areas 0 0 0.00
Block A Developable 0 0.00
0 0.0_0_ 80% _0_ _ Y 0.00
Block C 0 _ 0.00_ 80%� _ 0 m 0.00
Block D Developable 0 0.00 _ _ 80% 0 0.00_
_Block E .� 0 _ �m 0.00 - -- - v80 %- 0 0.00
Block F 0 _ -- 0.00 80 %_
Block G Developable 0 0.00 80% 0 0.00
—Block 0 0.00°' 0 0.00
B. Onsite Open Space Breakdown
Contributing Area Meas Area (sn % Open Open Area jstl Open Area
acres]
_ ROW Areas 0 10% 0 _0.00
Commercial Areas _.._r0 .� 20%�_._. _- 0 _ -_ ._..v 0.00
-- Managed Pervious 41 101 _ -100% 41,101 0.9_4_ W
Forest 85.363 100% 85363— 1.96
Tolal Measured Area 126,464 126,464 2.90
C. Watershed Breakdown
Contributin Area SCS CN Area sfj Area acres] Comments
Onsite impervious 98 0 0.00
_ Onsite open _ 63 41,101 _0.94 - Assume good condition
Onsite wooded 57 85,363 1.96 Assumeood condition
Onsrte pond 100 0 0.00 -
Offsite impervious 98 33,260 -
_ Ofis�te open_ 63 131,325 3.01 Assume good condition
OfTsite wooded ~57 8 777 0,20 Assume yzood condition
— `Offsite and — 100 0
Total Sub -basin Area = 6.88 acres
0.0108 sq.mi.
Composite SCS CN = 65
%Impervious= 11.1%

THE EDGE POST- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3- Bypass 5/23/2014
D. Time of Concentration Information
Tirane of conceivtn•ation is calcudaled using the SCS Segtnenial Approach (7'R -S5)
Segment 1: Overland Flow
Length =
1474
Length =
100
ft
Height =
3.5
ft
Slope=
0.0350
ft/ft
Manning's n =
0.40
wooded - light underbrush
P (2- year /24 -hour) =
3.6
inches (Chapel Hill, NC)
Segment Time =
16.19
minutes
Segment 3: Channel Flow
Length =
1474
Height=
51.5
Slope =
0.0349
Manning's n =
0.045
Flow Area =
9.00
Wetted Perimeter =
9.00
Channel Velocity =
6.19
Segment Time =
3.97
Time of Concentration = 20.15 minutes
SCS Lag Time = 12.09 minutes (SCS Lag = 0.6* Tc)
Time Increment = 3.51 minutes (= 0.29 *SCS Lag)
IIL; POST- DEVELOPME�14T RUN -OFF VOLEJME CALCULATIONS
Post developinew runoff volume calculations are based upon the SCS Method. The equation for this method is as folloias:
Q^ = ((P- 0.2•S)z)/ (P +o.VS)
where,
Q *= Direct Runofffinchesl
S ° Potential Abstraction (1000 /SCS Crave Minnie)) - 10
P — Accmtralated Storm Rainfall finches/
Per Town of Chapel Hill ordinance requirements, the increase in voh[me between pre- and post - development for the 2 -year
24 -hour slornn shall be treated within the proposed storn in ester management facility.
Post - development 2 -Year Runqff Volume Calculations
On -Site Area = 2.90 acres
On -site SCS CN = 59
S = 7.00
P (2 -yr / 24 -hour) = 3.60 inches
Q` = 0.53 inches
On -site Run -off Volume = 0.13 acre -feet
5541 cf
ft
ft
ft/ft
natural channel
sf (assume 3' x 3' channel)
If (assume Y x 3' channel)
ft/sec
minutes

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 -To SWMF 3 5/23/2014
IiSG Impervious Open Wooded
A 98 39 30
_ C 98__._ _ ..74 70
D _ 98 80 -- 77
Assume: HSG 'A' = 0%
HSG 'B' = 87%
HSG'C'= 13%
HSG 'D' = 0%
Cover Condition SCS CN Comments
Impervious 98
. �_.
_Open_ 63 _Assume good condition
Wooded 57 Assume good condition
II. POST-DEVELOPMENT":
A. Onsite Impervious Breakdown
Contributing Area� Meas Area Meas Area [sf[ '% Imp Imp Area jsfl Imp Area
_
[acres acres]
_ k A De_
ROW Areas _ 53,853 m 7.24 90% 48,468 1.11
• -. Blocvelopable_ 0 0.00 0.00
Block B 73,570 0. 1.69 _® 80% 58,856 1.35
_.�.. Block C 248,731 _.._ 5.71 80% 198,985 4.57
Block D Developable 195,071 4.48 80% 156,057 3.58
Block E 0 _0.00 80% 0 0.00
_Block F �-� 0 ._._ 0.00 J�m80 % f4 0 0.00
_ WBlock G Developable 0 0.00 _ 80 %m. ____ 0 _.� _ 0.00
TolalMeasuredArea 571,225 13.11 462,365 10.61
B. Onsite Open Space Breakdown
Contributing Area Meas Area (st] °f Open Open Area (Open Area
_ acres
_ROW Areas 53,853_ 10% 5,385 0.12
Commercial Areas 517,372 20 %� 103,474 2.38
Managed Pervious 45,000 100% 45,000 1.03
_ Forest 0�� 100%
Total Measured Areu 616,225 1 1 153,860 3.53
C. Watershed Breakdown
� Contributin Area SCS CN Areas Area acres Comments
Onsite im ervious 98 462,365 10.61 �_ -
_. _..pe.�___..'
Onsite oRep ��_ 63 w 153,860 3.53 q� p Assume good condition
Onsite wooded 57 0 0.00 Assumeood condition
Onsite pond 100 28,560 0.66 �wM�
Offsite
impervious 98 4,666 0.11
_ ._._._ _. _ . _. __. �.
mm Offsite open T _ 6_3_ W 61989 0.16_ Assume good condition
Offsite_wooded 57 0 0.00
100 0
-------,Assume good condition
Offsite ondv � 0.00 _ �"'� ^_�
Total Sub -basin Area = 15.07 acres
0.0235 sq.mi.
Composite SCS CN = 89
% Impervious = 71.1%

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 -To SWMF 3 5/23/2014
D. Time of Concentration Information
Time (i concentration is assumed to be 5 minutes.
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.87 minutes (= 0.29*SCS Lag)
ItI. POST- DEVELoktvENT IiUN =OFF VOLUME CALC II A"fIO1NS
Post - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q* = ((P- 0.2 *S)') / (P +0.8*S)
where,
Q" _= Direct Runoff (inchesil
S = Potential Abstraction => (1000 "SCS Curve Nunzbet) - 10
P Accumulated Storm Rainfall [inches)
Per Town ofChapel Hill ordinance requirements, the increase in volume between pre- and post- developmentfor the 2 -year
24 -hour .storm shall be treated within the proposed .slormwater management facility.
=> Post - development 2 -Year Runoff Volume Calculations
On -Site Area = 14.80 acres
On -site SCS CN = 90
S = 1.15
P (2 -yr / 24 -hour) = 3.60 inches
Q-= 2.51 inches
On -site Run -off Volume = 3.10 acre -feet
134891 cf

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 -To SWMF 4 5/23/2014
HSG
Impervious
Open
Wooded
A_
98
�39, �.
30
_B
f---
961
_
___. 55 _
90 %� 1
11,903_ 0
0.27
194,558 _
D.
80% -
155,646 W
3.57
Assume: HSG 'A' =
0%
HSG 'B' =
87%
O 0
HSG'C'=
13%
HSG'D'=
0%
Cover Condition
SC_S CN
Comments
Impervious _ mm_
98
80% 0
Open
__ 63
Assume good condition
Wooded
57_.___,.__.__
Asstune Good condition
II. POST- DEVELONN,1(ENT
A. Onsite Impervious Breakdown
Contributing Area
ROW Areas _
��Block A Developable
T Block B
Block C_
w� Block D Developable
Block E
Block F
_ Block G Developable
Total Measured Area
B. Onsite Open Space Breakdown
Contributing Area
ROW Areas
Commercial Areas
- Managed Pervious
Forest
Total Measured Arec
C. Watershed Breakdown
Contributin Area
291,587 5.78 202,592 4.65
Meas Area [sfJ % Open
13,2_26_ 109/.
__.238,361 - 20 %_
22,154 100%
6,992 —� 100%
Onsite impervious 98
Onsite open _M_63_ —
_ Onsite wooded _57
�Onsite pond 100_X
Offsite impervious T98
Offsite open 63 mm
1 7
Total Sub -basin Area =
Composite SCS CN =
% Impervious =
Open Area (sf] Open Area
_ acres
1,323 0.03
_ 47,672
22,154 0.51
6,992 _._.._ 0.16
!02,592 I
71,149
6,992 ___
14,609 _
3,954
7,019 M
0
7.03 acres
0.0110 sq.mi.
88
67.4%
a acres Comments
4.65
1.63 Assume good condition
_0.16 Assume good condition
0.34
0.16 mAssume ood condition
0.00 Assume good condition
Meas Area "
Imp Area
Meas Area (sf] M
acres �
"/o Imp I
Imp Area [sfj I
acres
13,226 0
0.30 9
90 %� 1
11,903_ 0
0.27
194,558 _
80% -
155,646 W
3.57
—O - - -- �
�--" -- 0
O 0
0.00 _
_80% —
0.00
800/.
0_.. 0
0.00 8
80% 0
0 0
0.00 m
_.0 ._ —
— 0.00_ 8
80% _ 0
0 w_ 0
0.00
-_ 0
0.00 8
80% 0
0
Meas Area [sfJ % Open
13,2_26_ 109/.
__.238,361 - 20 %_
22,154 100%
6,992 —� 100%
Onsite impervious 98
Onsite open _M_63_ —
_ Onsite wooded _57
�Onsite pond 100_X
Offsite impervious T98
Offsite open 63 mm
1 7
Total Sub -basin Area =
Composite SCS CN =
% Impervious =
Open Area (sf] Open Area
_ acres
1,323 0.03
_ 47,672
22,154 0.51
6,992 _._.._ 0.16
!02,592 I
71,149
6,992 ___
14,609 _
3,954
7,019 M
0
7.03 acres
0.0110 sq.mi.
88
67.4%
a acres Comments
4.65
1.63 Assume good condition
_0.16 Assume good condition
0.34
0.16 mAssume ood condition
0.00 Assume good condition
1 7
Total Sub -basin Area =
Composite SCS CN =
% Impervious =
Open Area (sf] Open Area
_ acres
1,323 0.03
_ 47,672
22,154 0.51
6,992 _._.._ 0.16
!02,592 I
71,149
6,992 ___
14,609 _
3,954
7,019 M
0
7.03 acres
0.0110 sq.mi.
88
67.4%
a acres Comments
4.65
1.63 Assume good condition
_0.16 Assume good condition
0.34
0.16 mAssume ood condition
0.00 Assume good condition
!02,592 I
71,149
6,992 ___
14,609 _
3,954
7,019 M
0
7.03 acres
0.0110 sq.mi.
88
67.4%
a acres Comments
4.65
1.63 Assume good condition
_0.16 Assume good condition
0.34
0.16 mAssume ood condition
0.00 Assume good condition

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin 3 -To SWMF 4 5/23/2014
D. Time of Concentration Information
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)
Time Increment = 0.87 minutes (= 0.29 *SCS Lag)
III. POST - DEVELOPMENT RUN' -OI F, VOLUN'IE CALGIIL.4TIONS
Post - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Q* = ((P- 0.2 *S)2) / (P +0.8 *S)
where,
Q* = Direct Runoff [inches]
S = Potential Abstraction => (1000 /SCS Curve Numbet) - 10
P = Accumulated Storm Rainfall [inches]
Per Town of Chapel Hill ordinance requirements, the increase in volume behveen pre- and post-developmentfor the 2 -year
24 -hour storm shall be treated within the proposed stormwater management facility.
= => Post - development 2 -Year Runoff Volume Calculations
On -Site Area = 6.78 acres
On -site SCS CN = 89
S= 1.28
P (2 -yr / 24 -hour) = 3.60 inches
Q* = 2.42 inches
On -site Run -off Volume = 1.36 acre -feet
59449 cf

THE EDGE POST - DEVELOPMENT IIYDROLOGY J. EASON, El
RAV -13000 Sub- bclsin 4 5/23/2014
1. SCS CURVE NUMBERS
HS_G
Impervious
Open
Wooded a..
98
30
_A
B
98
_39
61
55
C
70
D �..®.._._.
.._._._98
80
Assume: HSG'A'
HSG'B'
HSG'C'
HSG'D'
Cover Condition
bnpervious__
______qpen " _ `-
_ Wooded
0%
=
92%
0%
8%
SCS CN Comments
_G3 Assume_good condition
57 Assume good condition
A. Onsite Impervious Breakdown
Meas Area Imp Area
�
Contributing Area Meas Area [sf� % Imp Imp Area isff
acres _ acres
ROW Areas 0 _ 0.00 90% v_ 0 _ 0.00
Block A Developable 0 0.00 80% 0 0.00
u.�.._______ 0__._._........._._.. -._,._ . ��.__--._..._- _....._.....__.____.__..._._._.
Block B_ 0 _ 0.00 _ 80% _0_ 0.00 _
0.00 80% 0 _ 0.00
Block D Developable 0 0.00 _ 80 %- _ ___0 0.00
Block E O T _0.00 m 80%� 0 0.00
0.00 80% 0 0.00
Block G Develoable _TO 0.00 80% 0 0.00
'Total Measured Area 0 0.00 0 _ 0.00
B. Onsite Open Space Breakdown
Contributing Area Meas Area (sfJ % Open Open Area (sQ Open Area
__mROW Areas _ 0 U 10% 0 _ 0.0_0
C _
omercial Areas ._ 0 �20% mm 0 O.00�T
Managed Pervious W
Forest Omm 100 % 0 0.00
�. Total Measured Area 0. _ 0 0.00
C. Watershed Breakdown
Contributin Area SCS CN ents .AW
Onsite impervious _ 98 0 0.00
_ Onsite open _ 63 _ m 0 _ _0.00 _ _Assumeq condition
�_ Onsite wooded -' 57 0 _ .___. 0.00 Assume food condition
Onsrte pond 100 0 0.00 -
_ Offsite impervious T _ ___2_8_
Offsite Subdivision w_ 68 __ _ 690 852 W15,86 TR -55 CN for 1 acre Residential
Offsite open 63 _ 100403 2.30 some flood condition
Le_ _.....-._.._ _....___._ - _ v..__ .._...._..._._____
Offsite wooded _ 57 58,852 _ 1.35 Assu.Uood condition
Total Sub -basin Area =
Total area = 21.13 acres
0.0330 sq.mi.
Composite SCS CN = 69
% Impervious = 15.0%
D. Time of Concentration Information
Time ojconcenlralion is calculated using the SCS Segmemal Approach (T1?-SS).
Begnuent 1: Overland Flow Segment 2: Concentrated Flow
Length = 100 ft Length = 864 ft
Height = 5.5 ft Height = 31.5 ft
Slope = 0.0550 ft/ft Slope = 0.0365 ft/ft
Manning's n = 0.40 wooded - light underbrush Paved ? = No
P (2- year /24 -hour) = 3.6 inches (Chapel Hill, NC) Velocity= 3.08 ft /sec
Segment Time = 13.51 minntea .Vegment Tinte = 4.67 minutes
Time of Concentration = 18.18 minutes
SCS Lag Time = 10.91 minutes (SCS Lag = 0.6* Tc)
Time Increment = 116 minutes = 0.29 *SCS La

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin Unanalyzed 5/23/2014
HSG
Impery
en V1'ious Opooded
A
98
39 30
B
98
61 55
C
0.83
74 0 w
D
34,855
Assume: HSG 'A' =
0%
_
0
FISG'B'=
76%
HSG 'C' =
6%
I -ISG 'D' =
18%
_ 0.00 _
Cover Condition = SCS CN Comments ��
Impervious
98
0.00
Open
65 _
Assume good condition
Wooded
60
Assume good condition
A. Onsite Impervious Breakdown
Contributing Area Meas Area [sfj acres Meas Area % Imp Imp Area [sf] Imp Area
acres
ROW Areas 0 _0.00_ 90 %_ _ 0 0.00
Block A Developable _ 0 v 0.00_ 80% 0_ 0.00
v Block B 0� 0.00 _ 80% 0 0.00
_ Block_ C _ 0 0.00 80% 0 0.00
Block D Dever able 0 � _ 0.00 _._. 80% T �..0. 0.0_0
Block E v 0 _ 0.00 80% 0 0.00
Block F._.__ _ 0 0.00 80% 0 _ _. 0.00_tl
Block G Developable _0 0.00 80% 0 = 0.00
Total Measured Area 0 0.00 0 0.00
B. Onsite Open Space Breakdown
Contributing Area Meas Area [sf] % Open Open Area Is` Open Area
_ acres
__RO_W_A_reas_ 0 10% 0 0.00
Commercial Areas __ W 0 �20 %OLL 000
Managed Pervious 36,032 100% _ 36,032 _0.83
Forest
34,855 100% 34,855 0.80
Total 14ea.cured Area 70,887 70,887 1.63
C. Watershed Breakdown
ontributing Area SCS CN
Area sf
Area acres
Comments
Onsite impervious 98
0
0.00
Onsite open 65
�._ _ P__
36,032
0.83
Assume good condition
_. _
Onsite wooded_ 60
34,855
0.80_
_Assume good condition
Onsite pond 100
_
0
0.00
_ Offsite open 65
0
_ 0.00 _
Assume good condition
wooded 60�
0
0.00
Assume good condition
_Of&ai
Offsite pond 100~
0
0.00
Total Sub -basin Area =
1.63
acres
0.0025
sq.mi.
Composite SCS CN =
63
% Impervious =
0.0%

THE EDGE POST- DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Sub -basin Unanalyzed 5/23/2014
D. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6M Tc)
Time Increment = 0.87 minutes (= 0.29*SCS Lag)
IIi. kOST- DEVLLOT'IY[ES,'T RljN' -OVF VOLU E CAi.CIILA IONS
Post - development runoff volume calculations are based upon the SCS Method. The equation for this method is as follows:
Qx = ((P- 0.2 *S)2)/ (P +0.8 *S)
where,
QM = Direct Runoff [inches]
S = Potential Abstraction => (1000 /SCS Curve Number) - 10
P = Accumulated Storm Rainfall [inches]
Per Town ofChapel Hill ordinance requirements, the increase in volume between pre- and post - developmentfor the 2-year
24 -hour storm shall be treated within the proposed stormwater management facility.
= => Post - development 2 -Year Runoff Volume Calculations
On -Site Area = 1.63 acres
On -site SCS CN = 63
S = 5.98
P (2 -yr / 24 -hour) = 3.60 inches
Q* = 0.69 inches
On -site Run -off Volume = 0.09 acre -feet
4069 cf

THE EDGE POST - DEVELOPMENT HYDROLOGY J. EASON, El
RAV -13000 Reach Data 5/23/2014
IH. REACH DATA
REACH #5 - POA 2 TO POA 1
Time of concentration is calculated using the SCS Segmental Approach (71?-55)
Segment 1: Channel Flow
251
Height =
Length =
142
ft
Height =
2
ft
Slope =
0.0141
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 =
3.93
ft/sec
Segment Time =
0.60
minutes
Segment 2: Channel Flow
Length =
251
Height =
8.5
Slope =
0.0339
Manning's n =
0.045
Flow Area =
9.00
Wetted Perimeter =
9.00
Channel Velocity =
6.09
Segment Tinte =
0.69
Time of Concentration = 1.29 minutes
SCS Lag Time = 0.77 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.22 minutes (= 0.29 *SCS Lag)
REACrl 46 - POA 3 TO POA 2
Length =
Time of concentration is calculated using the
SCS Segmental
Approach (7777? -55).
Segment 1: Channel Flow
0.0182
Manning's n =
Length =
456
ft
Height =
10
ft
Slope =
0.0219
ft/ft
Manning's n =
0.013
RCP
Flow Area =
3.14
sf (assume 24" RCP)
Wetted Perimeter =
6.28
ft (assume 24" RCP)
Channel Velocity =
10.69
ft /sec
Segment Time =
0.71
minutes
Segment 2: Charnel Flow
Length =
1096
Height =
20
Slope =
0.0182
Manning's n =
0.045
Flow Area =
9.00
Wetted Perimeter =
9.00
Channel Velocity =
4.47
Segment Time =
4.08
'rime of Concentration = 4.79 minutes
SCS Lag Time = 2.88 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.83 minutes (= 0.29 *SCS Lag)
REACH #7 - POA 4 TO POA 3
Length =
Time of concentration is calculated using the SCS Segmental
Approach
Segment 1: Channel Flow
Segment 1: Pipe Flow
ft
Length =
716
ft
Height =
10
ft
Slope =
0.0140
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 =
2.99
ft/sec
Segment Time =
4.00
minutes
Time of Concentration = 4.00 minutes
SCS Lag Time = 2.40 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.70 minutes (= 0.29 *SCS Lag)
REACH 08 - SUB -BASIN 4 TO POA 4
Length =
Time of concentration is calculated using the
S( �S Segmental
Approach (77?-55).
Segment 1: Pipe Flow
ft
Slope =
Length =
528
ft
Height =
14
ft
Slope =
0.0265
ft /ft
Manning's n =
0.013
Concrete Pipe
P (2- year /24 -hour) =
3.6
inches (Chapel Hill, NC)
Segment Time =
4.42
minutes
ft
ft
ft/ft
natural channel
sf (assume 4' x 4' channel)
ft (assume Tx 4' channel)
ft /sec
minutes
ft
ft
ft /ft
natural channel
sf (assume 3' x 3' channel)
ft (assume 3' x 3' channel)
ft /sec
minutes
Segment 1: Concentrated Flow
Length =
53
ft
Height =
3
ft
Slope =
0.0566
JIM
Paved ? =
No
Velocity=
3.84
ft /sec
Segment Time =
0.23
minutes
Time of Concentration = 4.65 minutes
SCS Lag Time = 2.79 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.81 minutes (= 0.29 *SCS Lag)

'J MCADAMS
Scenario: Post Development
THE EDGE J. EASON, El
RAV 13000. ppc 1/23/2014

'J MCADAMS
Subsection: Master Network Summary
Pond Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ac -ft)
Maximum
Maximum
Water
Pond Storage
Surface
(ac -ft)
Elevation
(N /A)
(ft)
Post 1 Year
SWMF 1 (IN)
Post 1 Year
1
0.950
721.00
20.44
(N /A)
(N /A)
SWMF 1
Post 1 Year
1
0.309
1,083.00
0.32
468.21
0.710
(OUT)
SWMF 1 (IN)
Post 2 Year
2
1.220
721.00
24.84
(N /A)
(N /A)
SWMF 1
Post 2 Year
2
0.374
1,082.00
0.38
468.79
0.924
(OUT)
SWMF 1 (IN)
Post 25 Year
25
2.481
721.00
39.34
(N /A)
(N /A)
SWMF 1
Post 25 Year
25
1.190
751.00
8.88
470.09
1.432
(OUT)
SWMF 2 (IN)
Post 1 Year
1
2.870
721.00
62.19
(N /A)
(N /A)
SWMF 2
Post 1 Year
1
0.953
1,083.00
1.00
471.37
2.121
(OUT)
SWMF 2 (IN)
Post 2 Year
2
3.763
721.00
77.55
(N /A)
(N /A)
SWMF 2
Post 2 Year
2
1.211
1,082.00
1.25
472.06
2.804
(OUT)
SWMF 2 (IN)
Post 25 Year
25
8.006
721.00
129.50
(N /A)
(N /A)
SWMF 2
Post 25 Year
25
4.062
753.00
22.05
473.80
4.665
(OUT)
SWMF 3 (IN)
Post 1 Year
1
2.361
721.00
51.10
(N /A)
(N /A)
SWMF 3
Post 1 Year
1
0.729
1,083.00
0.76
505.15
1.778
(OUT)
SWMF 3 (IN)
Post 2 Year
2
3.074
721.00
63.16
(N /A)
(N /A)
SWMF 3
Post 2 Year
2
0.913
1,083.00
0.94
505.73
2.334
(OUT)
SWMF 3 (IN)
Post 25 Year
25
6.441
721.00
103.57
(N /A)
(N /A)
SWMF 3
Post 25 Year
25
3.044
754.00
15.96
507.22
3.890
(OUT)
SWMF 4 (IN)
Post 1 Year
1
1.054
721.00
22.83
(N /A)
(N /A)
SWMF 4
Post 1 Year
1
0.338
1,083.00
0.35
504.41
0.785
(OUT)
SWMF 4 (IN)
Post 2 Year
2
1.381
721.00
28.47
(N /A)
(N /A)
SWMF 4
Post 2 Year
2
0.426
1,083.00
0.44
504.96
1.039
(OUT)
SWMF 4 (IN)
Post 25 Year
25
2.939
721.00
47.54
(N /A)
(N /A)
SWMF 4
Post 25 Year
25
1.446
752.00
10.42
506.20
1.662
(OUT)
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

TUM-CADAMS
Subsection: Master Network Summary
Catchments Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ac -ft)
Sub 1 - Bypass
Post 1 Year
1
0.125
738.00
0.97
Sub 1 - Bypass
Post 2 Year
2
0.202
737.00
1.81
Sub 1 - Bypass
Post 25 Year
25
0.668
734.00
6.22
Sub - 1 to SWMF 1
Post 1 Year
1
0.950
721.00
20.44
Sub - 1 to SWMF 1
Post 2 Year
2
1.220
721.00
24.84
Sub - 1 to SWMF 1
Post 25 Year
25
2.481
721.00
39.34
Sub - 1 to SWMF 2
Post 1 Year
1
2.870
721.00
62.19
Sub - 1 to SWMF 2
Post 2 Year
2
3.763
721.00
77.55
Sub - 1 to SWMF 2
Post 25 Year
25
8.006
721.00
129.50
Sub - 2 Bypass
Post 1 Year
1
0.535
737.00
3.66
Sub - 2 Bypass
Post 2 Year
2
0.910
737.00
7.68
Sub - 2 Bypass
Post 25 Year
25
3.269
734.00
31.26
Sub - 3 Bypass
Post 1 Year
1
0.283
734.00
2.44
Sub - 3 Bypass
Post 2 Year
2
0.458
733.00
4.59
Sub - 3 Bypass
Post 25 Year
25
1.513
731.00
15.51
Sub - 3 to SWMF 3
Post 1 Year
1
2.361
721.00
51.10
Sub - 3 to SWMF 3
Post 2 Year
2
3.074
721.00
63.16
Sub - 3 to SWMF 3
Post 25 Year
25
6.441
721.00
103.57
Sub - 3 to SWMF 4
Post 1 Year
1
1.054
721.00
22.83
Sub - 3 to SWMF 4
Post 2 Year
2
1.381
721.00
28.47
Sub - 3 to SWMF 4
Post 25 Year
25
2.939
721.00
47.54
Sub - 4
Post 1 Year
1
1.153
732.00
12.52
Sub - 4
Post 2 Year
2
1.776
732.00
20.68
Sub - 4
Post 25 Year
25
1 5.321
1 730.00
1 58.54
Node Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ac -ft)
POA 1
Post 1 Year
1
4.405
747.00
20.57
POA 1
Post 2 Year
2
6.246
745.00
34.75
POA 1
Post 25 Year
25
20.467
747.00
137.22
POA 2
Post 1 Year
1
3.976
746.00
19.47
POA 2
Post 2 Year
2
5.674
744.00
32.93
POA 2
Post 25 Year
25
18.617
746.00
124.39
POA 3
Post 1 Year
1
2.498
741.00
15.40
POA 3
Post 2 Year
2
3.567
739.00
25.52
POA 3
Post 25 Year
25
11.309
741.00
84.05
POA 4
Post 1 Year
1
1.151
737.00
12.52
POA 4
Post 2 Year
2
1.772
737.00
20.68
POA 4
Post 25 Year
25
5.313
735.00
58.54
Sub -4o
Post 1 Year
1
1.153
732.00
12.52
Sub -4o
Post 2 Year
2
1.776
732.00
20.68
Sub -4o
Post 25 Year
25
1 5.321
1 730.00
58.54
'ond Summary
THE EDGE J. EASON, EI
RAV 13000. ppc 5/23/2014

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AREA = 21.13 —ac.
_OCK AREA
PERVIOUS
AREA
PERVIOUS
GRAPHIC S C AIE
150 0 75 150 300
1 inch = 150 ft.
PRELIMINARY DRAWING — NOT RELEASED FOR CONSTRUCTION
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PROJECT N0. RAV -13000
FILENAME: R AV13000- P OS
DESIGNED BY: —
DRAWN BY: JLE
SCALE: 1 "-150,
DATE:
05-23-2014
SHEET NO. POST
'J MCADAMS

STORMWA TER MANA GEMENT FA CILITY `I '
DESIGN CAL CULA TIONS
THE -EDGE
RAV -13000

the EDGE STORMWATER MANAGEMENT FACILITY 1 LEASON, EI
RAV -13000 SSFxn Above NP 1/27/2014
STAGE- STORAGE FUNCTION - ABOVE NORMAL POOL
Ks= 13014
h = 1.1289
Storage vs. Stage
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)
466.00
0.00
10,949
466.50
0.50
13,306
12128
6064_
6064
0.51
468.00
2.00
15,560
14433
21650
27713
1.95
470.00
4.00
17,636
16598
33196
60909
3.92 _
472.00
6.00
19,806
18721
37442
98351
6.00 ,
474.00
8.00
22,086
20946
41892
140243
8.21
Ks= 13014
h = 1.1289
Storage vs. Stage
160000
140000
y = 13014x1.1289
120000
R'= 0.9996
V
100000
rn
80000
A
60000
40000
20000
0
0.00
2.00 4.00 6.00 8.00 10.00
Stage (feet)
Ks= 13014
h = 1.1289

the EDGE STORMWATER MANAGEMENT FACILITY 1
RAV -13000 Surface Area Calculation
WET DETENTION BASIN SUMMARY
Enter the drainage area characteristics =_>
Total drainage area to pond = 5.56 acres
Total impervious area to pond = 394 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on -site development.
Drainage area = 5.56 acres 71.0% impervious
Estimate the surface area required at pond normal pool elevation =_>
Wet Detention Basins are based on an minimum average depth of =
3.01 feet (Calculated)
From the DWQ BMP Handbook, the required SAIDA ratio for
90% TSS Removal =_>
3.0
3.01
3.5
Lower Boundary => 70.0 4.00
3.70
Site % impervious => 71.0 4.05
4.04
3.74
Upper Boundary => 80.0 4.50
4.10
Therefore, SA /DA required =
4.04
Surface area required at normal pool =
9,784
ft2
=
0.22
acres
Surface area provided at normal pool =
10,949
ft2
J.EASON, EI
1/27/2014

the EDGE STORMWATER MANAGEMENT FACILITY 1
RAV -13000 WQV Calculation
DETERMINATION OF WATER QUALITY VOLUME
T'Q v = (P) (R v)(A) /I2
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:
13892 cf.
Total area, A =
5.56 acres
Impervious area =
3.94 acres
Percent impervious cover, I =
71.0 %
Rainfall, P =
1.00 inches
Calculated values:
Rv = 0.69
WQv= 0.32 acre -ft
13892 cf.
ASSOCIATED DEPTH IN POND
WQv=
13892 cf.
Stage/ Storage Data:
Ks =
13014
b =
1.129
Zo =
466.00
Volume in 1" rainfall =
13892 cf.
Calculated values:
Depth of WQv in Basin = 1.06 ft
12.71 inches
Elevation = 467.06 ft
J.EASON, EI
1/27/2014

the EDGE STORMWATER MANAGEMENT FACILITY 1
RAV -13000 WQV Calculation
DETERMINATION OF 2- YEAR/24 -HR VOLUME
2 -Year Volume = 54043 cf.
1.24 acre -ft
AssocIATED 2 -YEAR VOLUME DEPTH IN POND
2 -Year Volume=
54043 cf.
WQv=
13892 cf.
Volume Difference =
40151 cf.
Stage /Storage Data:
Ks=
13014
b =
1.129
Zo =
467.06
Volume of additional detention =
40151 cf.
Calculated values:
Depth of WQv in Basin = 2.71 ft
= 32.55 inches
Elevation = 469.77 ft
J.EASON, EI
1/27/2014

the EDGE STORMWATER MANAGEMENT FACILITY 1
RAV -13000 WQV Drawdown Calculation
D orifice =
2 inch
# orifices =
1
Ks =
13014
b =
1.1289
Cd siphon =
0.60
Normal Pool Elevation =
466.00 feet
Volume a Normal Pool =
0 of
Orifice Invert =
466.00 feet
WSEL a I" Runoff Volume =
467.06 feet
WSEL
feet
Vol. Stored
(C f)
Siphon Flow
cfs
Avg. Flow
(cfs )
Incr. Vol.
ef)
Incr. Time
sec
467.06
13892
0.104
466.97
12536
0.099
0.101
1356
13415
466.88
11196
0.093
0.096
1340
13961
466.78
9874
0.088
0.091
1322
14601
466.69
8572
0.082
0.085
1302
15363
466.60
7293
0.075
0.079
1280
16296
466.51
6038
0.068
0.072
1254
17480
466.41
4813
0.060
0.064
1225
19058
466.32
3623
0.051
0.056
1190
21331
466.23
2477
0.040
0.046
1147
25083
466.14
1389
0.023
0.032
1087
34516
Drawdown Time = 2.21 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.325 feet
Orifice composite loss coefficient = 0.600
Cross - sectional area of siphon = 0.022 sf
Q = 0.0599 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.68 da s
J.EASON, EI
5/22/2014

the EDGE STORMWATER MANAGEMENT FACILITY 1
RAV -13000 2 -Year Drawdown Calculation
DRAt�DOWN S,II')fiflt�i,I))ESIGI�I
D orifice =
2.5 inch
# orifices =
1
Ks=
13014
b =
1.1289
Cd siphon =
0.60
WSEL a V Runoff Volume =
467.06 feet
Orifice Invert =
467.10 feet
WSEL a 2- year /24 -hr Runoff Volume =
469.77 feet
WSEL
feet
Vol. Stored
c
Siphon Flow
(cfs )
Avg. Flow
(cfs )
Incr. Vol.
(cf)
Ina•. Time
sec
469.77
39475
0.265
469.54
35629
0.253
0.259
3846
14868
469.31
31830
0.240
0.246
3799
15423
469.08
28083
0.227
0.233
3748
16063
468.84
24391
0.212
0.220
3691
16813
468.61
20763
0.197
0.205
3628
17712
468.38
17206
0.181
0.189
3557
18819
468.15
13731
0.163
0.172
3475
20235
467.92
10355
0.142
0.152
3376
22150
467.68
7102
0.118
0.130
3253
24976
467.45
4015
0.088
0.103
3087
29909
Drawdown Time = 2.28 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.856 feet
Orifice composite loss coefficient = 0.600
Cross - sectional area of siphon = 0.034 sf
Q = 0.1519 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 3.01 days
J.EASON, EI
5/22/2014

M11 McADAMS
Subsection: Elevation -Area Volume Curve
Label: SWMF 1
Elevation Planimeter Area Al +A2 +sqr Volume
(ft) (ftz) (acres) (Al *A2) (ac -ft)
(acres)
Return Event: 1 years
Storm Event: 1 -Year
Volume (Total)
(ac -ft)
466.00
0.0
0.25
0.00
0.000
0.000
466.50
0.0
0.31
0.83
0.139
0.139
468.00
0.0
0.36
0.99
0.496
0.635
470.00
0.0
0.40
1.14
0.762
1.397
472.00
0.0
0.45
1.29
0.859
2.256
474.001
0.01
0.51
1 1.441
0.961
1 3.217
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

TJ MCADAMS
Subsection: Outlet Input Data
Label: SWMF 1
Requested Pond Water Surface Elevations
Minimum (Headwater) 466.00 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 474.00 ft
Return Event: 1 years
Storm Event: 1 -Year
Outlet Connectivity
Structure Type Outlet ID Direction Outfall El E2
(ft) (ft)
Inlet Box
RI
Forward
BA
469.80
474.00
Orifice - Circular
OR -2YR
Forward
BA
467.10
474.00
Culvert- Circular
BA
Forward
TW
465.00
474.00
Orifice - Circular
SI
Forward
TW
466.00
474.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON. El
RAV13000.ppc 1/27/2014

'J MCADAMS
Subsection: Outlet Input Data
Label: SWMF 1
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
95.00 ft
Length (Computed Barrel)
95.01 ft
Slope (Computed)
0.011 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
Return Event: 1 years
Storm Event: 1 -Year
TI Elevation 467.31 ft Ti Flow 15.55 ft3 /s
T2 Elevation 467.60 ft T2 Flow 17.77 ft3 /s
THE EDGE J. EASON, El
RAV13000.ppc 1/27/2014

TJ MCADAMS
Subsection: Outlet Input Data
Label: SWMF 1
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
469.80 ft
Orifice Area
16.0 ft2
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: SI
Structure Type: Orifice - Circular
Number of Openings
1
Elevation
466.00 ft
Orifice Diameter
2.0 in
Orifice Coefficient
1
Structure ID: OR -2YR
Structure Type: Orifice- Circular
Number of Openings
1
Elevation
467.10 ft
Orifice Diameter
2.5 in
Orifice Coefficient
1
Structure ID: TW
Structure Type: TW Setup, DS
Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 1 years
Storm Event: 1 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 1
Composite Outflow Summary
Water Surface Flow Tailwater Elevation Convergence Error
Elevation (ft3 /s) (ft) (ft)
(ft)
Return Event: 1 years
Storm Event: 1 -Year
Contributing Structures
466.00
0.00
(N /A)
0.00
(no Q: RI,OR- 2YR,BA,SI)
466.50
0.07
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
467.00
0.10
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
467.10
0.11
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
467.50
0.22
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
468.00
0.29
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
468.50
0.35
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
469.00
0.40
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
469.50
0.45
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
469.80
0.47
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
470.00
4.77
(N /A)
0.00
RI,OR- 2YR,BA,SI
470.50
28.47
(N /A)
0.00
RI,OR- 2YR,BA,SI
471.00
34.27
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
471.50
36.05
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
472.00
37.75
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
472.50
39.38
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
473.00
40.95
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
473.50
42.46
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
474.00
43.88
(N /A)
1 0.001
RI,BA,SI (no Q: OR -2YR)
THE EDGE
RAV 13000. ppc
J. EASON, El
1/27/2014

'J MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 1 (IN)
Infiltration
468.21 ft
Infiltration Method
No Infiltration
(Computed)
0.710 ac -ft
Initial Conditions
Elevation (Water Surface,
466.00 ft
Initial)
0.950 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Return Event: 1 years
Storm Event: 1 -Year
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 20.44 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.32 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
468.21 ft
Peak)
Volume (Peak)
0.710 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
0.950 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.309 ac -ft
Outflow)
Volume (Retained)
0.641 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.1 %
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 1 (IN)
Infiltration
468.79 ft
Infiltration Method
No Infiltration
(Computed)
0.924 ac -ft
Initial Conditions
Elevation (Water Surface,
466.00 ft
Initial)
1.220 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 2 years
Storm Event: 2 -Year
Flow (Peak In) 24.84 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.38 ft3 /s Time to Peak (Flow, Outlet) 1,082.00 min
Elevation (Water Surface,
468.79 ft
Pea k)
Volume (Peak)
0.924 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
1.220 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.374 ac -ft
Outflow)
Volume (Retained)
0.845 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.1 %
THE EDGE J. EASON. El
RAV 13000. ppc 1/27/2014

TJ MCADAMS
Subsection: Level Pool Pond Routing Summary Return Event: 25 years
Label: SWMF 1 (IN) Storm Event: 25 -Year
Infiltration
Infiltration Method No Infiltration
(Computed)
Initial Conditions
Elevation (Water Surface,
466.00 ft
Initial)
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Volume (Total Infiltration)
0.000 ac -ft
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 39.34 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 8.88 ft3 /s Time to Peak (Flow, Outlet) 751.00 min
Elevation (Water Surface,
470.09 ft
Peak)
Volume (Peak)
1.432 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
2.481 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
1.190 ac -ft
Outflow)
Volume (Retained)
1.290 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

TY McADAMS
Subsection: Outlet Input Data Return Event: 100 years
Label: SWMF 1 - WC Storm Event: 100 -Year
Requested Pond Water Surface Elevations
Minimum (Headwater) 466.00 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 474.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall E1 E2
(ft) (ft)
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014
Inlet Box
RI
Forward
BA
469.80
474.00
Culvert- Circular
BA
Forward
TW
465.00
474.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'JMcADaMs
Subsection: Outlet Input Data
Label: SWMF 1 - WC
Structure ID: BA
Form 1
Structure Type: Culvert- Circular
0.0098
Number of Barrels
1
Diameter
24.0 in
Length
95.00 ft
Length (Computed Barrel)
95.01 ft
Slope (Computed)
0.011 ft /ft
Slope Correction Factor
-1
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
Return Event: 100 years
Storm Event: 100 -Year
T1 Elevation 467.31 ft T1 Flow 15.55 ft3 /s
T2 Elevation 467.60 ft T2 Flow 17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J McADAMS
Subsection: Outlet Input Data
Label: SWMF 1 - WC
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
469.80 ft
Orifice Area
16.0 ftz
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 100 years
Storm Event: 100 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 1 - WC
Composite Outflow Summary
Return Event: 100 years
Storm Event: 100 -Year
Water Surface Flow Tailwater Elevation Convergence Error Contributing Structures
Elevation (ft3 /s) (ft) (ft)
(ft)
466.00
0.00
(N /A)
0.00
(no Q: RI,BA)
466.50
0.00
(N /A)
0.00
(no Q: RI,BA)
467.00
0.00
(N /A)
0.00
(no Q: RI,BA)
467.50
0.00
(N /A)
0.00
(no Q: RI,BA)
468.00
0.00
(N /A)
0.00
(no Q: RI,BA)
468.50
0.00
(N /A)
0.00
(no Q: RIBA)
469.00
0.00
(N /A)
0.00
(no Q: RI,BA)
469.50
0.00
(N /A)
0.00
(no Q: RIBA)
469.80
0.00
(N /A)
0.00
(no Q: RI,BA)
470.00
4.29
(N /A)
0.00
RI,BA
470.50
28.11
(N /A)
0.00
RIBA
471.00
34.03
(N /A)
0.00
RI,BA
471.50
35.81
(N /A)
0.00
RI,BA
472.00
37.50
(N /A)
0.00
RI,BA
472.50
39.12
(N /A)
0.00
RI,BA
473.00
40.67
(N /A)
0.00
RIBA
473.50
42.17
(N /A)
0.00
RI,BA
474.00
43.58
(N /A)
1 0.001
RIBA
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

9 MCADAMS
Subsection: Level Pool Pond Routing Summary Return Event: 100 years
Label: SWMF 1 (IN) Storm Event: 100 -Year
Infiltration
Infiltration Method No Infiltration
(Computed)
Initial Conditions
Elevation (Water Surface,
469.80 ft
Initial)
Volume (Initial)
1.317 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 47.92 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 30.98 ft3 /s Time to Peak (Flow, Outlet) 727.00 min
Elevation (Water Surface,
470.74 ft
Peak)
Volume (Peak)
1.704 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
1.317 ac -ft
Volume (Total Inflow)
3.205 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
3.196 ac -ft
Outflow)
Volume (Retained)
1.325 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON. El
RAV 13000. ppc 1/27/2014

STORMWA TER MANA GEMENT FA CILI T Y `T
DESIGN CAL CULA TIONS
THE -EDGE
RAV -13000

the EDGE STORMWATER MANAGEMENT FACILITY 2 J. EASON, EI
RAV -13000 SSFxn Above NP 1/27/2014
STAGE - STORAGE FUNCTION - ABOVE NORMAL POOL
Ks= 37220
b = 1.0951
Storage vs. Stage
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)
469.00
0.00
33,542
469.50
0.50
37,612
35577
17789
17789
0.51
470.00
1.00
38,864
38238
19119
36908
0.99
472.00
3.00
44,013
41439
82877
119785
2.91 _
474.00
5.00
49,388
46701
93401
213186
4.92
476.00
7.00
54,628
52008
104016
317202
7.07__
477.00
8.00 _
57,010
55819
55819
373021
8.20
Ks= 37220
b = 1.0951
Storage vs. Stage
400000
350000
y = 37220x 1 0951
300000
R'= 0.9996
V
250000
p
200000
150000
H
100000
50000
0
0.00
2.00 4.00 6.00 8.00 10.00
Stage (feet)
Ks= 37220
b = 1.0951

the EDGE STORMWATER MANAGEMENT FACILITY 2 J. EASON, El
RAV -13000 Sutface Area Calculation 1/27/2014
WET DETENTION BASIN SUitIMARY
Enter the drainage area characteristics = =>
Total drainage area to pond = 19.15 acres
Total impervious area to pond = 12.29 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on -site development.
Drainage area = 19.15 acres a 64.2% impervious
Estimate the surface area required at pond normal pool elevation = =>
Wet Detention Basins are based on an minimum average depth of
= 3.01 feet (Calculated)
From the DWQ BMP Handbook, the required SAIDA ratio for
90% TSS Removal = =>
3.0
3.01
3.5
Lower Boundary => 60.0 3.50
3.20
Site % impervious => 64.2 3.71
3.70
3.41
Upper Boundary — 70.0 4.00
3.70
Therefore, SA/DA required =
3.70
Surface area required at normal pool =
30,879
ft2
=
0.71
acres
Surface area provided at normal pool =
33,542
ft2

the EDGE STORMWATER MANAGEMENT FACILITY 2
RAV -13000 WQV Calculation
DETERMINATION OF WATER QUALI'T`Y VOLUME
WQ v = (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:
43614 cf.
"total area, A =
19.15 acres
Impervious area =
12.29 acres
Percent impervious cover, I =
64.2 %
Rainfall, P =
1.00 inches
Calculated values:
Rv = 0.63
WQv= 1.00 acre -ft
43614 cf.
ASSOCIATED DEPTH IN POND
WQv=
43614 cf.
Stage /Storage Data:
Ks=
37220
b =
1.095
Zo =
469.00
Volume in V rainfall =
43614 cu. ft
Calculated values:
Depth of WQv in Basin = 1.16 ft
= 13.87 inches
Elevation = 470.16 ft
J. EASON, El
1/27/2014

the EDGE STORMWATER MANAGEMENT FACILITY 2
RAV -13000 WQV Calculation
2 -Year Volume = 166291 cf.
3.82 acre -ft
2 -Year Volume=
166291
cf.
WQv=
43614
cf.
Volume Difference =
122678
cf.
Stage / Storage Data:
Ks=
37220
b =
1.095
Zo =
470.16
Volume of additional detention =
122678
cf.
Calculated values:
Depth of 2 -yr in Basin = 2.97 ft
= 35.66 inches
Elevation = 473.13 It
J. EASON, EI
5/22/2014

the EDGE STORMWATER MANAGEMENT FACILITY 2
RAV -13000 WQV Drawdown Calculation
I3R4W.D(}WN SIl'FI©N;DESJ N'
D orifice =
# orifices =
Ks =
b=
Cd siphon =
Normal Pool Elevation =
Volume @ Normal Pool =
Orifice Invert =
WSEL n 1" Runoff Volume
3.5 inch
1
37220
1.0951
0.60
469.00 feet
0 of
469.00 feet
470.16 feet
WSEL
feet
Vol. Stored
c f)
Siphon Flow
(cfs )
Avg. Flow
(cfs)
Iner. Vol.
c
Iner. Time
sec
470.16
43614
0.323
470.05
39439
0.306
0.314
4175
13276
469.95
35302
0.289
0.297
4137
13913
469.85
31207
0.270
0.279
4095
14669
469.75
27158
0.250
0.260
4049
15589
469.65
23161
0.228
0.239
3997
16746
469.55
19224
0.203
0.216
3938
18265
469.45
15355
0.176
0.190
3868
20398
469.34
11571
0.143
0.159
3785
23739
469.24
7892
0.093
0.118
3679
31124
469.14
4361
0.041
0.067
3531
52386
Drawdown Time = 2.55 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.337 feet
Orifice composite loss coefficient = 0.600
Cross- sectional area of siphon = 0.067 sf
Q = 0.1867 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.70 da s
J. EASON, El
5/22/2014

the EDGE STORMWATER MANAGEMENT FACILITY 2
RAV -13000 2-Year Drawdown Calculation
D orifice =
4.5 inch
# orifices =
1
Ks=
37220
b =
1.0951
Cd siphon =
0.60
WSEL a 1" Runoff Volume=
470.16 feet
Orifice Invert =
470.20 feet
WSEL a 2- year /24 -hr Runoff Volume =
473.13 feet
WSEL
(feet)
Vol. Stored
cf)
Siphon Flow
cfs
Avg. Flow
(cfs)
Iner. Vol.
c
Iner. Time
sec
473.13
120679
0.886
472.87
109151
0.844
0.865
11528
13326
472.61
97728
0.800
0.822
11423
13894
472.36
86420
0.754
0.777
11308
14555
472.10
75240
0.704
0.729
11180
15340
471.85
64203
0.651
0.677
11037
16294
471.59
53328
0.593
0.622
10874
17493
471.33
42644
0.528
0.560
10684
19069
471.08
32190
0.454
0.491
10454
21281
470.82
22027
0.366
0.410
10163
24763
470.56
12268
0.249
0.308
9759
31725
Drawdown Time = 2.17 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.913 feet
Orifice composite loss coefficient = 0.600
Cross - sectional area of siphon = 0.110 sf
Q = 0.5082 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.75 da s
J. EASON, EI
5/22/2014

T"il McADAMS
Subsection: Elevation -Area Volume Curve
Label: SWMF 2
Elevation Planimeter Area Al +A2 +sqr
(ft) (ftz) (ftz) (Al *A2)
(ft2)
Return Event: 1 years
Storm Event: 1 -Year
Volume Volume (Total)
(ac -ft) (ac-ft)
469.00
0.0
33,542.00
0.00
0.000
0.000
469.50
0.0
37,612.00
106,672.75
0.408
0.408
470.00
0.0
38,864.00
114,708.88
0.439
0.847
472.00
0.0
44,013.00
124,235.45
1.901
2.748
474.00
0.0
49,388.00
140,024.11
2.143
4.891
476.00
0.0
54,628.00
155,957.96
2.387
7.278
477.001
0.01
57,010.00
1 167,444.29
1 1.281
1 8.560
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

TJ MCADAMS
Subsection: Outlet Input Data Return Event: 1 years
Label: SWMF 2 Storm Event: 1 -Year
Requested Pond Water Surface Elevations
Minimum (Headwater) 469.00 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 477.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall El E2
(ft) (ft)
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014
Inlet Box
RI
Forward
BA
473.20
477.00
Orifice - Circular
OR -2YR
Forward
BA
470.20
477.00
Culvert- Circular
BA
Forward
TW
468.60
477.00
Orifice - Circular
SI
Forward
Tw
469.00
477.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

TJ MCADAMS
Subsection: Outlet Input Data
Label: SWMF 2
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
113.00 ft
Length (Computed Barrel)
113.00 ft
Slope (Computed)
0.005 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Return Event: 1 years
Storm Event: 1 -Year
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
Ti Elevation 470.92 ft Ti Flow 15.55 ft3 /s
T2 Elevation 471.21 ft T2 Flow 17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

'J McADAMS
Subsection: Outlet Input Data
Label: SWMF 2
Structure ID: RI
Structure Type: Inlet Box
Number of Openings .
1
Elevation
473.20 ft
Orifice Area
16.0 ftz
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft"0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: SI
Structure Type: Orifice- Circular
Number of Openings
1
Elevation
469.00 ft
Orifice Diameter
3.5 in
Orifice Coefficient
1
Structure ID: OR -2YR
Structure Type: Orifice - Circular
Number of Openings
1
Elevation
470.20 ft
Orifice Diameter
4.5 in
Orifice Coefficient
1
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 1 years
Storm Event: 1 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

91 MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 2
Composite Outflow Summary
Water Surface Flow Tailwater Elevation Convergence Error
Elevation (ft3 /s) (ft) (ft)
(ft)
Return Event: 1 years
Storm Event: 1 -Year
Contributing Structures
469.00
0.00
(N /A)
0.00
(no Q: RI,OR- 2YR,BA,SI)
469.50
0.19
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
470.00
0.30
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
470.20
0.33
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
470.50
0.53
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
471.00
0.85
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
471.50
1.06
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
472.00
1.23
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
472.50
1.37
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
473.00
1.49
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
473.20
1.54
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
473.50
9.49
(N /A)
0.00
RI,OR- 2YR,BA,SI
474.00
30.50
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
474.50
32.28
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
475.00
33.97
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
475.50
35.58
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
476.00
37.15
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
476.50
38.64
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
477.00
40.09
(N /A)
1 0.001
RI,BA,SI (no Q: OR -2YR)
THE EDGE
RAV13000.ppc
J. EASON. El
5/23/2014

9 MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 2 (IN)
Infiltration
471.37 ft
Infiltration Method
No Infiltration
(Computed)
2.121 ac -ft
Initial Conditions
Elevation (Water Surface,
469.00 ft
Initial)
2.870 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Return Event: 1 years
Storm Event: 1 -Year
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 62.19 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 1.00 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
471.37 ft
Peak)
Volume (Peak)
2.121 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
2.870 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.953 ac -ft
Outflow)
Volume (Retained)
1.915 ac -ft
Volume (Unrouted)
-0.003 ac -ft
Error (Mass Balance)
0.1 %
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

'JI MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 2 (IN)
Infiltration
472.06 ft
Infiltration Method
No Infiltration
(Computed)
2.805 ac -ft
Initial Conditions
Elevation (Water Surface,
469.00 ft
Initial)
3.763 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 2 years
Storm Event: 2 -Year
Flow (Peak In) 77.55 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 1.25 ft3 /s Time to Peak (Flow, Outlet) 1,082.00 min
Elevation (Water Surface,
472.06 ft
Pea k)
Volume (Peak)
2.805 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
3.763 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
1.211 ac -ft
Outflow)
Volume (Retained)
2.548 ac -ft
Volume (Unrouted)
-0.003 ac -ft
Error (Mass Balance)
0.1 %
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

J MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 2 (IN)
Infiltration
473.80 ft
Infiltration Method
No Infiltration
(Computed)
4.665 ac -ft
Initial Conditions
Elevation (Water Surface,
469.00 ft
Initial)
8.006 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 25 years
Storm Event: 25 -Year
Flow (Peak In) 129.50 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 22.05 ft3 /s Time to Peak (Flow, Outlet) 753.00 min
Elevation (Water Surface,
473.80 ft
Pea k)
Volume (Peak)
4.665 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
8.006 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
4.062 ac -ft
Outflow)
Volume (Retained)
3.941 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON. El
RAV 13000. ppc 5/23/2014

'J1 MCADAMS
Subsection: Outlet Input Data Return Event: 100 years
Label: SWMF 2 - WC Storm Event: 100 -Year
Requested Pond Water Surface Elevations
Minimum (Headwater) 469.00 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 477.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall E1 E2
(ft) (ft)
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014
Inlet Box
RI
Forward
BA
473.20
477.00
Culvert- Circular
BA
Forward
TW
468.60
477.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

J MCADAMS
Subsection: Outlet Input Data Return Event: 100 years
Label: SWMF 2 - WC Storm Event: 100 -Year
Structure ID: BA
Structure Type: Culvert- Circular
0.013
Number of Barrels
1
Diameter
24.0 in
Length
113.00 ft
Length (Computed Barrel)
113.00 ft
Slope (Computed)
0.005 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
TI ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
TI Elevation 470.92 ft T1 Flow
15.55 ft3 /s
T2 Elevation 471.21 ft T2 Flow
17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

'J MCADAMS
Subsection: Outlet Input Data
Label: SWMF 2 - WC
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
473.20 ft
Orifice Area
16.0 ftz
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 100 years
Storm Event: 100 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

'J MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 2 - WC
Composite Outflow Summary
Return Event: 100 years
Storm Event: 100 -Year
Water Surface Flow Tailwater Elevation Convergence Error Contributing Structures
Elevation (ft3 /s) (ft) (ft)
(ft)
469.00
0.00
(N /A)
0.00
(no Q: RI,BA)
469.50
0.00
(N /A)
0.00
(no Q: RIBA)
470.00
0.00
(N /A)
0.00
(no Q: RI,BA)
470.50
0.00
(N /A)
0.00
(no Q: RI,BA)
471.00
0.00
(N /A)
0.00
(no Q: RI,BA)
471.50
0.00
(N /A)
0.00
(no Q: RIBA)
472.00
0.00
(N /A)
0.00
(no Q: RI,BA)
472.50
0.00
(N /A)
0.00
(no Q: RI,BA)
473.00
0.00
(N /A)
0.00
(no Q: RI,BA)
473.20
0.00
(N /A)
0.00
(no Q: RI,BA)
473.50
7.88
(N /A)
0.00
RIBA
474.00
29.79
(N /A)
0.00
RI,BA
474.50
31.54
(N /A)
0.00
RI,BA
475.00
33.20
(N /A)
0.00
RI,BA
475.50
34.77
(N /A)
0.00
RI,BA
476.00
36.30
(N /A)
0.00
RI,BA
476.50
3737
(N /A)
0.00
RI,BA
477.00
1 39.19
(N /A)
1 0.001
RIBA
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

'J MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 2 (IN)
Infiltration
475.78 ft
Infiltration Method
No Infiltration
(Computed)
7.007 ac -ft
Initial Conditions
Elevation (Water Surface,
473.20 ft
Initial)
10.472 ac -ft
Volume (Initial)
4.005 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Return Event: 100 years
Storm Event: 100 -Year
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 159.76 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 35.63 ft3 /s Time to Peak (Flow, Outlet) 752.00 min
Elevation (Water Surface,
475.78 ft
Pea k)
Volume (Peak)
7.007 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
4.005 ac -ft
Volume (Total Inflow)
10.472 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
10.399 ac -ft
Outflow)
Volume (Retained)
4.075 ac -ft
Volume (Unrouted)
-0.003 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON, El
RAV 13000. ppc 5/23/2014

STORMWA TER MANAGEMENT FACILITY `3'
DESIGN CAL CULA TIONS
THE -EDGE
RAV -13000

the EDGE STORMWATER MANAGEMENT FACILITY 3 J. EASON, EI
RAV -13000 SSFxn Above NP 1/27/2014
STAGE - STORAGE FUNCTION - ABOVE NORMAL POOL
Ks= 33845
b = 1.1442
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)
503.00
0.00
28,560
503.50
0.50
34,485
31523
15761
15761
— 0.51
504.00
1.00
36,293
35389
17695
33456
0.99
506.00
3.00
43,666
39980
79959
113415
2.88
_
508.00
5.0_0
51,268
47467
94934
208349
4.90
510.00
7.00
59.094
55181
110362
318711
7.10
511.00
8.00
63,092
61093
61093
379804
8.27
Ks= 33845
b = 1.1442

the EDGE STORMWATER MANAGEMENT FACILITY 3
RAV -13000 Surface Area Calculation
WE°I`'1}MNTION BASIN SUVINIAR'
Enter the drainage area characteristics =_>
"Total drainage area to pond = 15.07 acres
Total impervious area to pond = 10.72 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on -site development.
Drainage area = 15.07 acres a 71.1% impervious
Estimate the surface area required at pond normal pool elevation = =>
Wet Detention Basins are based on an minimum average depth of =
3.01 feet (Calculated)
From the DWQ BMP Handbook, the required SAIDA ratio for
90% TSS Removal =>
3.0
3.01
3.5
Lower Boundary => 70.0 4.00
3.70
Site % impervious => 71.1 4.06
4.05
3.75
Upper Boundary => 80.0 4.50
4.10
Therefore, SA /DA required =
4.05
Surface area required at normal pool =
26,593
ft2
=
0.61
acres
Surface area provided at normal pool =
28,560
ft2
.l. EASON, EI
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 3
RAV -13000 WQV Calculation
DETERNU ATION OT -WATER QUALITY VOLUME
TVQ v = (P) (R v)(A) /I2
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:
37763 cf.
Stage/ Storage Data:
"total area, A =
15.07
acres
hnpervious area =
10.72
acres
Percent impervious cover, I =
71.1
%
Rainfall, P =
1.00
inches
Calculated values:
Rv = 0.69
WQv= 0.87 acre -ft
37763 cf.
ASSOCIATED DEPTH IV POND .
WQv=
37763 cf.
Stage/ Storage Data:
Ks=
33845
b =
1.144
Zo =
503.00
Volume in 1" rainfall =
37763 cu. ft
Calculated values:
Depth of WQv in Basin = 1.10 ft
13.21 inches
Elevation = 504.10 ft
J. EASON, El
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 3
RAV -13000 WQV Calculation
2 -Year Volume = 138737 cf.
3.18 acre -ft
2 -Year Volume=
138737
cf.
WQv =
37763
cf.
Volume Difference =
100975
cf.
Stage /Storage Data:
Ks=
33845
b =
1.144
Zo =
504.10
Volume of additional detention =
100975
cf.
Calculated values:
Depth of 2 -yr in Basin = 2.60 ft
31.19 inches
Elevation = 506.70 ft
J. EASON, El
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 3
RAV -13000 WQV Drawdown Calculation
DRAWDOWN SIPHON DESIGN 0
Vol. Stored
c f)
D orifice =
3.25 inch
# orifices =
1
Ks=
33845
b =
1.1442
Cd siphon =
0.60
Normal Pool Elevation =
503.00 feet
Volume @ Normal Pool=
0 cf
Orifice Invert =
503.00 feet
WSEL @ I" Runoff Volume =
504.10 feet
WSEL
feet
Vol. Stored
c f)
Siphon Flow
(cfs )
Avg. Flow
(cfs)
Incr. Vol.
(c
Incr. Time
sec
504.10
37763
0.272
504.01
34043
0.258
0.265
3719
14026
503.91
30375
0.244
0.251
3669
14617
503.81
26761
0.228
0.236
3614
15314
503.72
23208
0.212
0.220
3553
16157
503.62
19723
0.194
0.203
3485
17207
503.53
16313
0.174
0.184
3409
18571
503.43
12992
0.151
0.162
3321
20455
503.34
9775
0.125
0.138
3217
23336
503.24
6689
0.087
0.106
3087
29235
503.15
3776
0.041
0.064
2912
45679
Drawdown Time = 2.48 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice =
0.322 feet
Orifice composite loss coefficient =
0.600
Cross - sectional area of siphon =
0.058 sf
Q=
0.1573 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.78 days
J. EASON, EI
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 3
RAV -13000 2- Year Drawdown Calculation
D orifice =
4 inch
# orifices =
1
Ks =
33845
b =
1.1442
Cd siphon =
0.60
WSEL a 1" Runoff Volume =
504.10 feet
Orifice Invert =
504.20 feet
WSEL @ 2- year /24 -hr Runoff Volume =
506.70 feet
WSEL
(feet)
Vol. Stored
c
Siphon Flow
(cfs)
Avg. Flow
(cfs)
Incr. Vol.
W)
Incr. Time
(see)
506.70
96563
0.654
506.48
87111
0.625
0.640
9453
14780
506.27
77786
0.594
0.609
9325
15307
506.05
68600
0.561
0.577
9186
15914
505.84
59567
0.526
0.543
9033
16623
505.62
50704
0.489
0.507
8863
17471
505.41
42033
0.448
0.468
8671
18512
505.19
33582
0.404
0.426
8450
19838
504.98
25394
0.354
0.379
8188
21622
504.76
17530
0.295
0.325
7864
24233
504.55
10097
0.222
0.259
7432
28726
Drawdown Time = 2.23 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.778 feet
Orifice composite loss coefficient = 0.600
Cross - sectional area of siphon = 0.087 sf
Q = 0.3706 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 3.02 da s
J. EASON, El
5/23/2014

U11 McADAMS
Subsection: Outlet Input Data
Label: SWMF 3
Return Event: 1 years
Storm Event: 1 -Year
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
59.00 ft
Length (Computed Barrel)
59.00 ft
Slope (Computed)
0.008 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
T1 Elevation 504.81 ft T1 Flow
15.55 ft3 /s
T2 Elevation 505.11 ft T2 Flow
17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'-'_1J McADAMS
Subsection: Outlet Input Data
Label: SWMF 3
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
506.80 ft
Orifice Area
16.0 ft2
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: SI
Structure Type: Orifice- Circular
Number of Openings
1
Elevation
503.00 ft
Orifice Diameter
3.3 in
Orifice Coefficient
1
Structure ID: OR -2YR
Structure Type: Orifice- Circular
Number of Openings
1
Elevation
504.20 ft
Orifice Diameter
4.0 in
Orifice Coefficient
1
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 1 years
Storm Event: 1 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 3
Composite Outflow Summary
Water Surface Flow Tailwater Elevation Convergence Error
Elevation (ft3 /s) (ft) (ft)
(ft)
Return Event: 1 years
Storm Event: 1 -Year
Contributing Structures
503.00
0.00
(N /A)
0.00
(no Q: RI,OR- 2YR,BA,SI)
503.50
0.17
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
504.00
0.26
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
504.20
0.29
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
504.50
0.46
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
505.00
0.71
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
505.50
0.87
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
506.00
1.01
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
506.50
1.12
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
506.80
1.19
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
507.00
5.52
(N /A)
0.00
RI,OR- 2YR,BA,SI
507.50
28.95
(N /A)
0.00
RI,OR- 2YR,BA,SI
508.00
32.76
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
508.50
34.66
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
509.00
36.47
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
509.50
38.19
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
510.00
39.84
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
510.50
41.41
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
511.001
42.94
(N /A)
1 0.001
RI,BA,SI (no Q: OR -2YR)
THE EDGE
RAV13000.ppc
J. EASON, El
1/27/2014

!U1 MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 3 (IN)
Infiltration
505.15 ft
Infiltration Method
No Infiltration
(Computed)
1.778 ac -ft
Initial Conditions
Elevation (Water Surface,
503.00 ft
Initial)
2.361 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Return Event: 1 years
Storm Event: 1 -Year
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 51.10 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.76 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
505.15 ft
Peak)
Volume (Peak)
1.778 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
2.361 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.729 ac -ft
Outflow)
Volume (Retained)
1.631 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.1%
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

U' MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 3 (IN)
Infiltration
505.73 ft
Infiltration Method
No Infiltration
(Computed)
2.334 ac -ft
Initial Conditions
Elevation (Water Surface,
503.00 ft
Initial)
3.074 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Return Event: 2 years
Storm Event: 2 -Year
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 63.16 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.94 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
505.73 ft
Pea k)
Volume (Peak)
2.334 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
3.074 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.913 ac -ft
Outflow)
Volume (Retained)
2.158 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.1%
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Level Pool Pond Routing Summary Return Event: 25 years
Label: SWMF 3 (IN) Storm Event: 25 -Year
Infiltration
Infiltration Method No Infiltration
(Computed)
Initial Conditions
Elevation (Water Surface,
503.00 ft
Initial)
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Flow (Peak In) 103.57 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 15.96 ft3 /s Time to Peak (Flow, Outlet) 754.00 min
Elevation (Water Surface,
507.22 ft
Peak)
Volume (Peak)
3.890 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
6.441 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
3.044 ac -ft
Outflow)
Volume (Retained)
3.394 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

'J MCADAMS
Subsection: Outlet Input Data
Label: SWMF 3 - WC
Requested Pond Water Surface Elevations
Minimum (Headwater) 503.00 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 511.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall
Return Event: 100 years
Storm Event: 100 -Year
E1 E2
(ft) (ft)
Inlet Box
RI
Forward
BA
506.80
511.00
Culvert- Circular
BA
Forward
TW
502.50
511.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

Tj MCADAMS
Subsection: Outlet Input Data
Label: SWMF 3 - WC
Return Event: 100 years
Storm Event: 100 -Year
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
59.00 ft
Length (Computed Barrel)
59.00 ft
Slope (Computed)
0.008 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
T1 Elevation 504.81 ft TI Flow
15.55 ft3 /s
T2 Elevation 505.11 ft T2 Flow
17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

M11 McADAMS
Subsection: Outlet Input Data
Label: SWMF 3 - WC
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
506.80 ft
Orifice Area
16.0 ftz
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^o.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0.01 ft
(Minimum)
Tailwater Tolerance
0.50 ft
(Maximum)
Headwater Tolerance
0.01 ft
(Minimum)
Headwater Tolerance
0.50 ft
(Maximum)
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 100 years
Storm Event: 100 -Year
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

T 1 MCADAMS
Subsection: Composite Rating Curve
Label: SWMF 3 - WC
Composite Outflow Summary
Water Surface Flow
Elevation (ft3 /s)
(ft)
Return Event: 100 years
Storm Event: 100 -Year
Tailwater Elevation Convergence Error Contributing Structures
(ft) (ft)
503.00
0.00
(N /A)
0.00
(no Q: RI, BA)
503.50
0.00
(N /A)
0.00
(no Q: RI, BA)
504.00
0.00
(N /A)
0.00
(no Q: RI,BA)
504.50
0.00
(N /A)
0.00
(no Q: RIBA)
505.00
0.00
(N /A)
0.00
(no Q: RI,BA)
505.50
0.00
(N /A)
0.00
(no Q: RI,BA)
506.00
0.00
(N /A)
0.00
(no Q: RI,BA)
506.50
0.00
(N /A)
0.00
(no Q: RI,BA)
506.80
0.00
(N /A)
0.00
(no Q: RI,BA)
507.00
4.29
(N /A)
0.00
RI,BA
507.50
28.11
(N /A)
0.00
RI,BA
508.00
32.15
(N /A)
0.00
RI, BA
508.50
34.02
(N /A)
0.00
RIBA
509.00
35.80
(N /A)
0.00
RI,BA
509.50
37.49
(N /A)
0.00
RI,BA
510.00
39.11
(N /A)
0.00
RIBA
510.50
40.66
(N /A)
0.00
RI,BA
511.001
42.16
(N /A)
1 0.00
1 RI,BA
THE EDGE
RAV13000.ppc
J. EASON, El
1/27/2014

'J MCADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 3 (IN)
Infiltration
3.429 ac -ft
Infiltration Method
No Infiltration
(Computed)
0.000 ac -ft
Volume (Total Outlet
8.320 ac -ft
Initial Conditions
Elevation (Water Surface,
506.80 ft
Initial)
-0.002 ac -ft
Volume (Initial)
3.429 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 100 years
Storm Event: 100 -Year
Flow (Peak In) 127.20 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 34.46 ft3 /s Time to Peak (Flow, Outlet) 734.00 min
Elevation (Water Surface, 508.62 ft
Peak)
Volume (Peak) 5.529 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
3.429 ac -ft
Volume (Total Inflow)
8.390 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
8.320 ac -ft
Outflow)
Volume (Retained)
3.497 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.0%
THE EDGE J. EASON, El
RAV 13000. ppc 1/27/2014

ST®RMWA TER MANA GEMENT EA CILITY `4'
DESIGN CAL CULATI ®NS
THE -EDGE
RAV -13000

the EDGE STORMWATER MANAGEMENT FACILITY 4 J.EASON, EI
RAV -13000 SSFxn Above NP 5/22/2014
STAGE - STORAGE FUNCTION - ABOVE NORMAL POOL
Contour
(feet)
Stage
(feet)
Contour
Area
(SF)
Average
Contour
Area
(SF)
Incremental
Contour
Volume
(CF)
Accumulated
Contour
Volume
(CF)
Estimated
Stage
w/ S -S Fxn
(feet)
502.50
0.00
14,609
503.00
0.50
17,370
15990
7995
7995
0.51
504.00
1.50
19,102
18236
18236
26231
1.47
505.00
2.50
20,890
19996
19996
46227
2.45
506.00
3.50
22,383
21637
21637
67863
3.45
508.00
5.50
25,419
23901
47802
115665
5.55
509.00
6.50
26,972
26196
26196
141861
6.66
Ks= 16974
b = 1.1198

the EDGE STORMWATER MANAGEMENT FACILITY 4
RAV -13000 Surface Area Calculation
Enter the drainage area characteristics = =>
Total drainage area to pond = 7.03 acres
Total impervious area to pond = 4.74 acres
Note The basin inust be sized to treat all impervious sui face runoff draining into the pond, not just the impervious
surface from on -site development.
Drainage area = 7.03 acres @ 67.4% impervious
Estimate the surface area required at pond normal pool elevation = =>
Wet Detention Basins are based on an minimum average depth of
= 3.01 feet (Calculated)
From the DWQ BMP Handbook, the required SA /DA ratio for
90% TSS Removal =>
3.0
3.01
3.5
Lower Boundary => 60.0 3.50
3.20
Site % impervious — 67.4 3.87
3.87
3.57
Upper Boundary => 70.0 4.00
3.70
Therefore, SA /DA required =
3.87
Surface area required at normal pool =
11,841
ftz
=
0.27
acres
Surface area provided at normal pool =
14,609
ftz
J.EASON, El
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 4
RAV -13000 WQV Calculation
WQ v = (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 = 7.03 acres
Impervious area = 4.74 acres
Percent impervious cover, I = 67.4 %
Rainfall, P = 1.00 inches
Calculated values:
Rv = 0.66
WQv= 0.38 acre -ft
16767 cf.
WQv=
16767 cf.
Stage/ Storage Data:
Ks =
16974
b =
1.120
Zo =
502.50
Volume in 1" rainfall =
1 6767 cu. ft
Calculated values:
Depth of WQv in Basin = 099 ft
11.87 inches
Elevation = 503.49 ft
J.EASON, EI
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 4
RAV -13000 WQV Calculation
DE'TERI **IINA [`tON OF 2- t'EAR/24 -HR VOLt�MG
2 -Year Volume = 61144 cf.
1.40 acre -ft
ASSOCIATED 2- YEAR,VOLt�14IE DEPTIL IN POND
2 -Year Volume=
61144
cf.
WQv=
16767
cf.
Volume Difference =
44377
cf.
Stage /Storage Data:
Ks=
16974
b =
1.120
Zo =
503.49
Volume of additional detention =
44377
cf.
Calculated values:
Depth of 2 -yr in Basin = 2.36 ft
28.31 inches
Elevation = 505.85 ft
J.EASON, EI
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 4
RAV -13000 WQV Drawdown Calculation
DRA"t''DOWN SIPH ©N 4E,S[GN,'
D orifice =
# orifices =
Ks =
b=
Cd siphon =
Normal Pool Elevation =
Volume a Normal Pool =
Orifice Invert =
WSEL a 1" Runoff Volume =
2.25 inch
1
16974
1.1198
0.60
502.50 feet
0 of
502.50 feet
503.49 feet
WSEL
(feet)
Vol. Stored
W)
Siphon Flow
(efs)
Avg. Flow
(efs)
Iner. Vol.
(cf)
Iner. Time
sec
503.49
16767
0.126
503.40
15139
0.119
0.122
1629
13295
503.32
13529
0.113
0.116
1610
13865
503.23
11939
0.106
0.109
1590
14535
503.14
10371
0.098
0.102
1567
15338
503.06
8829
0.090
0.094
1542
16330
502.97
7315
0.082
0.086
1514
17603
502.89
5834
0.072
0.077
1481
19325
502.80
4393
0.060
0.066
1441
21870
502.71
3001
0.046
0.053
1392
26274
502.63
1677
0.023
0.034
1324
38710
Drawdown Time = 2.28 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.298 feet
Orifice composite loss coefficient = 0.600
Cross- sectional area of siphon = 0.028 sf
Q = 0.0726 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.67 days
J.EASON, EI
5/23/2014

the EDGE STORMWATER MANAGEMENT FACILITY 4
RAV -13000 2 -Year Drawdown Calculation
DRAWDOWN SIPHON DESIGN
D orifice =
2.75 inch
# orifices =
1
Ks =
16974
b =
1.1198
Cd siphon =
0.60
WSEL @ V Runoff Volume =
503.49 feet
Orifice Invert =
503.50 feet
WSEL @ 2- year /24 -hr Runoff Volume =
505.85 feet
WSEL
feet
Vol. Stored
c
Siphon Flow
cfs
Avg. Flow
(cfs )
Incr. Vol.
(c
Incr. Time
sec
505.85
44147
0.297
505.64
39862
0.283
0.290
4285
14771
505.44
35626
0.269
0.276
4236
15355
505.23
31442
0.253
0.261
4183
16033
505.03
27318
0.237
0.245
4124
16835
504.82
23260
0.219
0.228
4058
17804
504.62
19276
0.200
0.210
3984
19013
504.42
15379
0.179
0.189
3897
20587
504.21
11586
0.155
0.167
3793
22768
504.01
7923
0.126
0.140
3663
26130
503.80
4438
0.088
0.107
3485
32557
Drawdown Time = 2.34 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.744 feet
Orifice composite loss coefficient= 0.600
Cross - sectional area of siphon = 0.041 sf
Q = 0.1714 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2.98 days
J.EASON, EI
5/23/2014

Subsection: Elevation -Area Volume Curve
Label: SWMF 4
Return Event: 1 years
Storm Event: 1 -Year
Elevation Planimeter Area Al +A2 +sqr Volume Volume (Total)
(ft) (ftz) (ftz) (Ai *A2) (ac -ft) (ac -ft)
(ft2)
502.50
0.0
14,609.00
0.00
0.000
0.000
503.00
0.0
17,370.00
47,908.79
0.183
0.183
504.00
0.0
19,102.00
54,687.43
0.41.8
0.602
505.00
0.0
20,890.00
59,968.01
0.459
1.061
506.00
0.0
22,383.00
64,896.62
0.497
1.557
508.00
0.0
25,419.00
71,654.75
1.097
2.654
509.00
1 0.01
26,972.00
1 78,574.99
1 0.601
1 3.255
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014

22i'MCADAMS
Subsection: Outlet Input Data Return Event: 1 years
Label: SWMF 4 Storm Event: 1 -Year
Requested Pond Water Surface Elevations
Minimum (Headwater) 502.50 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 509.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall E1 E2
(ft) (ft)
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014
Inlet Box
RI
Forward
BA
505.90
509.00
Orifice - Circular
OR -2YR
Forward
BA
503.50
509.00
Culvert- Circular
BA
Forward
TW
501.50
509.00
Orifice - Circular
SI
Forward
TW
502.50
509.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014

Subsection: Outlet Input Data
Label: SWMF 4
Return Event: 1 years
Storm Event: 1 -Year
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
77.00 ft
Length (Computed Barrel)
77.00 ft
Slope (Computed)
0.006 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
T1 ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
T1 Elevation 503.81 ft T1 Flow
15.55 ft3 /s
T2 Elevation 504.11 ft T2 Flow
17.77 ft3 /s
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014

MI
MCADAMS
Subsection: Outlet Input Data
Label: SWMF 4
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
505.90 ft
Orifice Area
16.0 ft2
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: SI
Structure Type: Orifice - Circular
Number of Openings
1
Elevation
502.50 ft
Orifice Diameter
2.3 in
Orifice Coefficient
1
Structure ID: OR -2YR
Structure Type: Orifice - Circular
Number of Openings
1
Elevation
503.50 ft
Orifice Diameter
2.8 in
Orifice Coefficient
1
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
(Minimum)
0.01 ft
Tailwater Tolerance
(Maximum)
0.50 ft
Headwater Tolerance
(Minimum)
0.01 ft
Headwater Tolerance
(Maximum)
0.50 ft
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 1 years
Storm Event: 1 -Year
THE EDGE J. EASON, El
RAV13000.ppc 5/22/2014

1 CADAS
Subsection: Composite Rating Curve
Label: SWMF 4
Composite Outflow Summary
Water Surface Flow Tailwater Elevation Convergence Error
Elevation (ft3 /s) (ft) (ft)
(ft)
Return Event: 1 years
Storm Event: 1 -Year
Contributing Structures
502.50
0.00
(N /A)
0.00
(no Q: RI,OR- 2YR,BA,SI)
503.00
0.08
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
503.50
0.13
(N /A)
0.00
SI (no Q: RI,OR- 2YR,BA)
504.00
0.28
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
504.50
0.37
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
505.00
0.45
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
505.50
0.50
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
505.90
0.54
(N /A)
0.00
OR- 2YR,BA,SI (no Q: RI)
506.00
2.07
(N /A)
0.00
RI,OR- 2YR,BA,SI
506.50
22.81
(N /A)
0.00
RI,OR- 2YR,BA,SI
507.00
32.42
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
507.50
34.31
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
508.00
36.10
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
508.50
37.81
(N /A)
0.00
RI,BA,SI (no Q: OR -2YR)
509.00 1
39.44
(N /A)
1 0.00
1 RI,BA,SI (no Q: OR -2YR)
THE EDGE
RAV13000.ppc
J. EASON, El
5/22/2014

x 1
L
Subsection: Level Pool Pond Routing Summary
Label: SWMF 4 (IN)
Infiltration
504.41 ft
Infiltration Method
No Infiltration
(Computed)
0.785 ac -ft
Initial Conditions
Elevation (Water Surface,
502.50 ft
Initial)
1.054 ac -ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 1 years
Storm Event: 1 -Year
Flow (Peak In) 22.83 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.35 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
504.41 ft
Peak)
Volume (Peak)
0.785 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
1.054 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
0.338 ac -ft
Outflow)
Volume (Retained)
0.714 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.2%
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014

1 McADAMS
Subsection: Level Pool Pond Routing Summary
Label: SWMF 4 (IN)
Infiltration
Infiltration Method No Infiltration
(Computed)
Initial Conditions
Elevation (Water Surface,
502.50 ft
Initial)
504.96 ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 2 years
Storm Event: 2 -Year
Flow (Peak In) 28.47 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 0.44 ft3 /s Time to Peak (Flow, Outlet) 1,083.00 min
Elevation (Water Surface,
Peak)
504.96 ft
Volume (Peak)
1.039 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
1.381 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
Outflow)
0.426 ac -ft
Volume (Retained)
0.954 ac -ft
Volume (Unrouted)
-0.002 ac -ft
Error (Mass Balance)
0.1 %
THE EDGE
J. EASON, El
RAV13000.ppc 5/22/2014

�I' 1
Subsection: Level Pool Pond Routing Summary
Label: SWMF 4 (IN)
Infiltration
47.54 ft3 /s
Infiltration Method
No Infiltration
(Computed)
10.42 ft3 /s
Time to Peak (Flow, Outlet)
752.00 min
Initial Conditions
1.446 ac -ft
Elevation (Water Surface,
1.492 ac -ft
Initial)
502.50 ft
Volume (Initial)
0.000 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 ft3 /s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 25 years
Storm Event: 25 -Year
Flow (Peak In)
47.54 ft3 /s
Time to Peak (Flow, In)
721.00 min
Flow (Peak Outlet)
10.42 ft3 /s
Time to Peak (Flow, Outlet)
752.00 min
Outflow)
1.446 ac -ft
Volume (Retained)
1.492 ac -ft
Elevation (Water Surface, 506.20 ft
Peak)
Volume (Peak) 1.661 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
0.000 ac -ft
Volume (Total Inflow)
2.939 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
Outflow)
1.446 ac -ft
Volume (Retained)
1.492 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.0%
THE EDGE
J. EASON, El
RAV 13000. ppc 5/22/2014

�1 McADAMS
Subsection: Outlet Input Data Return Event: 100 years
Label: SWMF 4 - WC Storm Event: 100 -Year
Requested Pond Water Surface Elevations
Minimum (Headwater) 502.50 ft
Increment (Headwater) 0.50 ft
Maximum (Headwater) 509.00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall El E2
(ft) (ft)
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014
Inlet Box
RI
Forward
BA
505.90
509.00
Culvert- Circular
BA
Forward
TW
501.50
509.00
Tailwater Settings
Tailwater
(N /A)
(N /A)
THE EDGE J. EASON, El
RAV 13000. ppc 5/22/2014

r
Subsection: Outlet Input Data
Label: SWMF 4 - WC
Structure ID: BA
Structure Type: Culvert- Circular
Number of Barrels
1
Diameter
24.0 in
Length
77.00 ft
Length (Computed Barrel)
77.00 ft
Slope (Computed)
0.006 ft /ft
Outlet Control Data
Manning's n
0.013
Ke
1
Kb
0
Kr
0
Convergence Tolerance
0.00 ft
Inlet Control Data
Equation Form
Form 1
K
0.0098
M
2.0000
C
0.0398
Y
0.6700
Ti ratio (HW /D)
1
T2 ratio (HW /D)
1
Slope Correction Factor
-1
Use unsubmerged inlet control 0 equation below T1
elevation.
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control,
interpolate between flows at T1 & T2...
Return Event: 100 years
Storm Event: 100 -Year
Ti Elevation 503.81 ft T1 Flow 15.55 ft3 /s
T2 Elevation 504.11 ft T2 Flow 17.77 ft3 /s
THE EDGE J. EASON, El
RAV13000.ppc 5/22/2014

�.J
Subsection: Outlet Input Data
Label: SWMF 4 - WC
Structure ID: RI
Structure Type: Inlet Box
Number of Openings
1
Elevation
505.90 ft
Orifice Area
16.0 ft2
Orifice Coefficient
1
Weir Length
16.00 ft
Weir Coefficient
3.00 (ft ^0.5) /s
K Reverse
1
Manning's n
0
Kev, Charged Riser
0
Weir Submergence
False
Orifice H to crest
False
Structure ID: TW
Structure Type: TW Setup, DS Channel
Tailwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
(Minimum)
0.01 ft
Tailwater Tolerance
(Maximum)
0.50 ft
Headwater Tolerance
(Minimum)
0.01 ft
Headwater Tolerance
(Maximum)
0.50 ft
Flow Tolerance (Minimum)
0.001 ft3 /s
Flow Tolerance (Maximum)
10.000 ft3 /s
Return Event: 100 years
Storm Event: 100 -Year
THE EDGE
RAV13000,ppc J. EASON, El
5/22(2014

McADAMS
Subsection: Composite Rating Curve
Label: SWMF 4 - WC
Composite Outflow Summary
Return Event: 100 years
Storm Event: 100 -Year
Water Surface Flow Tailwater Elevation Convergence Error Contributing Structures
Elevation (ft3 /s) (ft) (ft)
(ft)
502.50
0.00
(N /A)
0.00
(no Q: RI,BA)
503.00
0.00
(N /A)
0.00
(no Q: RI,BA)
503.50
0.00
(N /A)
0.00
(no Q: RI,BA)
504.00
0.00
(N /A)
0.00
(no Q: RI,BA)
504.50
0.00
(N /A)
0.00
(no Q: RIBA)
505.00
0.00
(N /A)
0.00
(no Q: RIBA)
505.50
0.00
(N /A)
0.00
(no Q: RIBA)
505.90
0.00
(N /A)
0.00
(no Q: RI,BA)
506.00
1.52
(N /A)
0.00
RIBA
506.50
22.30
(N /A)
0.00
RIBA
507.00
32.14
(N /A)
0.00
RIBA
507.50
34.02
(N /A)
0.00
RIBA
508.00
35.79
(N /A)
0.00
RI,BA
508.50
37.49
(N /A)
0.00
RI,BA
509.00 1
39.11
(N /A)
1 0.00
1 RI,BA
THE EDGE J. EASON. El
RAV13000.ppc 5/22/2014

x , h
Subsection: Level Pool Pond Routing Summary
Label: SWMF 4 (IN)
Infiltration
Infiltration Method
No Infiltration
(Computed)
2.104 ac -ft
Initial Conditions
Elevation (Water Surface,
1.506 ac -ft
Initial)
505.90 ft
Volume (Initial)
1.506 ac -ft
Flow (Initial Outlet)
0.00 ft3 /s
Flow (Initial Infiltration)
0.00 ft3 /s
Flow (Initial, Total)
0.00 W/s
Time Increment
1.00 min
Inflow /Outflow Hydrograph Summary
Return Event: 100 years
Storm Event: 100 -Year
Flow (Peak In) 58.65 ft3 /s Time to Peak (Flow, In) 721.00 min
Flow (Peak Outlet) 32.25 ft3 /s Time to Peak (Flow, Outlet) 728.00 min
Elevation (Water Surface,
Peak)
507.03 ft
Volume (Peak)
2.104 ac -ft
Mass Balance (ac -ft)
Volume (Initial)
1.506 ac -ft
Volume (Total Inflow)
3.844 ac -ft
Volume (Total Infiltration)
0.000 ac -ft
Volume (Total Outlet
Outflow)
3.822 ac -ft
Volume (Retained)
1.527 ac -ft
Volume (Unrouted)
-0.001 ac -ft
Error (Mass Balance)
0.0%
THE EDGE
RAV13000.ppc J. EASON, El
5/22/2014

NUTRIENT L OADING CAL C ULA TIONS
THE -EDGE
RAV -13000

Jordan Lake Developer Nutrient Reporting Form
(Note: A separate form is available for Neuse, Tar - Pamlico, and Falls Lake reporting.)
Please complete and submit the following information to the local government permitting your development project to
characterize it and assess the need to purchase nutrient offsets. Contact and rule implementation information can be
found online at http: / /Dortal.ncdenr.org/ web /wa /ps /nps /nutrientoffsetintro.
_............__._ ------------------ _............--_.................................. ............_..._.._.__...._.__ _ -------- _... --- ...............__.._.._ ... _ ..... ........ _ ......... ................................... ... _ ............ __..........._.__._.........__. ...._..__._. -------------- .__..
PROJECT INFORMATION (for Jordan Lake) i
......... ......... ...._. ....... .. _.....__......_ ...... _...-... ... .................. __._............__..__.. ......................... _.. ... ..... ..... ................................... .......... ....................... ........ -..._............._......................_..-.......... .......... .................__...-. --------- _......_....._........ ..... ...... . ........._....................I
Applicant Name:
Northwood Ravin (Developer)
................. _ ........... _._ ...... _ ........... _.__ ..... _ .......... _ ............................................. .._._-__. .............. _ ............... . ........ _._...__ ................................ _. ......................... ......... _ ................................ __.........__ ..... ---_ ............... ._.__ ............ _ .......................... . ........ _._ ...... ._-------- .._ .....................
_
i Project Name:
the EDGE
t........... ........._......_ .............. __..-..._ ................................... ......_...._....------.........._...................._.... ........_.............__._..... _ ........ ._. .... ............. �.._._._........._..--........_.._._......__........_._..._................_............---- ------------- _ ---- ......................... _ .... ....._... - _......_
Project Address (if available): Street: City/Town: County:
_ .. ........... __.._._..................Chapel Hill Orange
......... _--- .............._.._.......... _............... ..........._................... .-------._.. ................_.._ ......... . - .......... ... ..............._ ............ _ .... ._ ........ _._..........._........... ..........._..._..__...___-._..._........._.......__..............-.__...._..._..----.................._-
Date: (mo /d/yr) Project Lat: (decimal degrees) Long: (decimal degrees)
05/23/2014 ;Location : 35.581406 - 79.066583
....... `_ ................. . ............ __ ....... ._ ............... _ .... __._...._.._.... ........._.._ ........ ..... _ --------- ......... _ .......... - ........
...................... ................_. ... _ ............. ------- ............. -.-_---_ ............................... _. ... .-._. ........... _.--- ........ --- ......... ........... - ....__ ............... ......_ :
i
Is this Redevelopment? ❑ -Yes Development Type (Please check all that apply)
® -No
.... . .................. ....._...........- ....... _ _ ._.._ - - ...._.......,_....._.................._._._..............,
.......... . ........... �...._.._. ................... . ........ . ............ .__...
...... ..... _. ........................ . ........... . .. _ . ............ ... . ........... . ... .... ...... ...... . ...... ....................... _ . .............. . ............ . .. . ........ . ....
......._ _
Impervious Cover % : 1.53% Commercial Mixed -Use Single Fam. Residential
j (Pre- Construction)
i._._ ..............._.._ ........ ._ _ .... _.................. ....._.._. Industrial
__............... . Multi -Fam. Residential D p l
Impervious Cover
61.61
i
;
❑ � Institutional
(Post- Construction)
�
JORDAN WATERSHED INFORMATION
.
.... ............_ ......... ...................._ ........................ _ ........ .... ._-.._._ ----------------------- ._-_. ........ .......................... ._...._.._........_--........................ _ .... ._. ........... .-_.___.... ..... _ ........ __. .... .- ............... _ ............ _ .................................... --- ......... __.. .............. ..._.. - __-........... ...
....._...
1 Small Watershed ID (6 digits): (See next page or online map.) New Development Load Requirements (See individual rules
1 060110 for a full description of nutrient requirements.) j
._...___._............_ .............._....__._.._......_....._......__._.................._._.._._..__........_..............-_...._-_...---....._......_....__... _.._...._...__�.........._..___ ._..........._......__.._... ............._.._._.._.. _._........_...._..--- ....................... _.._ ........ ....__ _.__.._......................_,
Jordan Subwatershed Please check one) Loading Rate Targets
Offsite Thresholds
(
I_ ......................._.......,_ ............. _-__ ......................... _..__ ........... _.._ ....... __.._ ..... ___ .............._ ...... ___ ........... Nitro N&_.hosphorus (P) . i
.... _ ....... .. I
f__ ......._......_........__........___-...._.._......._ ........_.....................i
I ❑ E Haw River i 3.8 N Ib /ac/yr
1.43 P Ib /ac /yr
._.._._.- _._ .... ... _......__..____...____....__._-_....__ ..... _ ......... .._ ....... _ .... _.__.._...._.___..._.__ ..................___ _..._.... ... . _ _ ._.__......_..--.... ....._........._._....._....... 6 N Ibs /ac Residential;
I
® Upper New Hope 2.2 N Ib /ac/yr 10 N Ibs /ac Commercial
! 0.82 P Ib /ac /yr (must meet all onsite treatment `
... .... __............_- _...__ .......... __._. _........ _.........._.._. __. _ .. ............................... __. _....................._ -.
,_.._._ ..... ........ _ _................._.._._.... ...__........... _ .__ ......... requirements) c
I I 0 8 Plbb /ac/ rr
❑ Lower New Hope y
... ...... - ----- -- -._. --. �...._.--_...._ ........................._..._......._...__._....._...._.._........_.......-......._....._....................._.............................. ....._...._......_..._.._'............ ......._............._......... ...__.._....__.._._ .... ...... - ................ _ ... _ ...... _ .... ...__..._. ..... _. ._ ............. _...._ .........
.
NUTRIENT OFFSET REQUEST(Must meet the offsite thresholds - see above)
......... . ................. -_ .... __.._ ....................... _...__ ................. ..__ ............. _ ................ _._ .... _ ................ _....... _ ............................ _.._.._ ............... .... ._....................... _.. _..._..._....-_. ......... _ ............ _..._._.. ................. _............... - ... __ ...................... .__ .............. _!
Nitrogen Loading / Offset Needs
_..._..__.._ ....... ....__..._.........;._.__._..__._..._........_ ............. ........... ......_._. ................. _ ............ ,._ .......... _ ... _ .................. ......_.__._:........................ _ .... __ ... .................._... _ ............... _... ... ._ -:- ......... ................ __. ....._... _.._._...._........._..__...._. ............_. .. I
(A) I (B) j (C) (D) (E) (F) (G) (H) (1) (Where Applicable)
Untreated i Treated i Loading Rate j Reduction Need Project Offset Delivery State Buy Down Local Gov't Buy Down
I Loading Rate Loading Rate i Target I (Ibs /ac/yr) Size (ac) Duration (yrs) Factor ( %) Amount (Ibs) i Amount (Ibs)
(Ibs /aGyr) I (Ibs /ac/yr) (Ibs /ac /yr) B - C € D' E * F' G
_...._._....._..._.........._..... .... _..........._......_ .................. _....._.......__.._................._............................_... ......_......_._...............
_ ............._ .__.._...............__.._.._..,......_.__............_..................................._.._.._.........................._......... e._........................._..... ........__..._......_.__.._....
8.85 6.26 2.20 I 4.06 51.03 30 69 4288.66
,
I
Phosphorus Loading / Offset Needs [
....._.. ._._.._......_._.____..._......................... _.._.....i... _........._-._., ..... ..._..._._ .....................
(A) (B) (C) I (D) (E) (F) (G) (H) (i) (Where Applicable) [
Untreated Treated Loading Rate i Reduction Need i Project Offset Delivery State Buy Down Local Gov't Buy Down
i Load Rate Load Rate Target (Ibs /aGyr) Size (ac) Duration (yrs) Factor ( %) Amount (Ibs) Amount (Ibs) i
(Ibs /ac /yr) (Ibs /ac /yr) (Ibs /acJyr) i
i— ........... _ ................_................. _......._...................... ............... ....._....._........._.._ ........�..................8... _C.._................,......... _ -..__...._._ ....._..._................._.._ _. ....i......._..—_............._ �._ . E . F � C?....... .................................. __._..._.__ .... .............
_
--- ....._�_:6 . :78 _L .. - ....._0 82 N/A . _ ..__._. 51.03 ._...... _ 3....— ._......I..... _ 63 .. ............_..1..........._... _ N/A
..._. _.:_....__....._._...... .................._....._...._i
.. _..._... � ...... _..._.
Authorizing Local Government Name: Chapel Hill, NC
.............._.................._..._......... r .........._....._.___.___....._ _ _._......__..._..._.._.._..._. _._...__......................_ -__ .............. --- ............. __.- ........ __ ... _.._ ...................... _.._ ............ _. ... _ ...... _ ..... _.._..._ ................................... --_ ... - .__ ................... _ ...
1
Staff Name: Chris Jensen
_........... ...._ ........ . ......... _ ........... ..............._..... __ ............................ _.--.............. __ ... _ ....... _ ...... ............ __._ ................... _ .... -__.__ ............ ---__ ........ _.._ .......... ------ ........ -.._......._.._ ... ....... .................. .... .... _ ............ _..- ................... _._.. ................... ....
Staff Email: { cjensen @townofchapelhill.org Phone: [phone]
—_. ............ ... __ ................. _. ......... _!.
.......... _ ... __ .............. _.._......._ ................ .._ ............ _ ...... - ....... ...... .__. .... _ .......... _._ ........ __`_ ............. ____ .............. . —. ........ —__._. l._._.._......................... .............................. .._ .......... __ ........... _ ____-...._. ........ _......._...
Jordan Nutrient Load Reporting Form. September 12, 2012

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BMP CharacteristicsVer2.0 Retwrntowatershed Proceed to Development
Clear All Values Return to Instructions - Characteristics Summary
Instructions
1. Select the type of BMP for each catchment.
2. Enter the area of each land use type in the contributing drainage area for each BMP.
3. Continue to "Development Summary " tab.
Additional Guidelines
This spreadsheet allows the development to be divided into as many as 6 smaller catchments.
BMPS 1, 2, and 3 for a given catchment are assumed to operate in series, with the outflow from 1 serving as the inflow to 2, etc.
If the outflow from an entire catchment (including outflow from selected BMPS) drains to another BMP, indicate this in the drop down menu below the BMP type and leave all cells for individual land uses blank.
- Not all BMP or catchments must be utilized. Simply leave fields blank in the columns not needed.
- Leave cells blank or insert zeroes if a land use is not present in the area draining to the BMP.
- For water harvesting BMPS, be sure to enter the percent volume reduction that will be achieved by your system. Volume detention (catch- and - release mechanisms) will not be considered - only proven volume reductions are valid inputs.
- The BMP ur dersaing option should only be used for existing development or retrofit sites.
- Volume reduction efficiencies for undersized BMPS are calculated based an a 1:1 ratio (a BMP that is 60% smaller than the required design size is assigned a removal efficiency equal to 6D% of the standard efficiency
value). Effluent concentrations remain the same as full -sized BMP,.
- IMPORTANT: for the land area calculation checks to occur, you MUST press enter after entering a value for area to be treated by a BMP (not just click on the rent cell).
See User's Manual for instructions on modeling oversized BMPS.
Type of BMP:
If BMP Is wid p Wd, irtdio . ttre BMP's sba
relative to the design si a required to
aPtum the dasiVWW water quality depth
P.a. 0.75 = amp Is 75% of required design
site):
•For water harvesting BMP, enter percent
volume reduction In dedmal form.
Catchment 1:
Catchment 2:
Catchment 3:
Catchment 4:
Catchment S:
Catchment 6:
Drainage Area Land Use
COMMERCIAL
Parking lot
Roof
Open /Landscaped
INDUSTRIAL
Parking lot.
Roof
Open /Landsc p d
TRANSPORTATION
High Density (interstate, main)
Low Density (secondary, feeder)
Rural
Sidewalk
.SC. PERVIOUS
Managed pery ous
Unmanaged_( pasture)
Forest
RESIDENTIAL
2 -
2 -ac lots:New)
ac lots (Built after 1995)
2 c lots (Built before 1995)
1 ac lots (New)
1 -ac lots (euil[ after 1995)
1 -ac lots (Built before 1995)
% -ac lots New)
/. -ac ,t,: Built after 1995)
,A-.c lots feu in before 1995)
A -ac lots (New)
'' /. -ac lots (Built after 1995)
V.-ac lots ( Built before 1995)
aclots(New)
ac lots (Built after 1995)
' /roc lots (Built before 1995)
Townhomes(New)
Townhomes (Built after 1995)
Townhomes (Built before 1995)
Multi - family (New)
Multi tam'ly (BU It after 1995)
Mul[ fam ly (BU It before 1995)
Custom Lo[ 'ze (New)
C tom LotS5ze ( BUlt after 1995)
C tom Lot Size (Built before 1995)
R adway
Driveway
Parking lot
Roof
Sid-11,
Lawn
Managed pe
Forest
LAND TAKEN UP BY BMP
TOTAL AREA TREATED BY BMP (ft')
TOTAL AREA TREATED BY SERIES (ft'):
--------------------------- LAIL. —I 1 ______________________
amp #1 BMP #2 8MP#3
Wet Detention
Pond
no
no
no
no
no
do no
no no
no no
no
no do
Area treated Area treated
Area Treated
by BMP #2 that is by BMP #3 that is
by BMP
nottreatedby BMP nottreated by BMP,
(ft'I
#1 #1 or #2
(ft')
Ift'1 lR'1
103,0]0
(ft') (ft')
51,535
#1 or #2
59,269
(ft')
(ft')
_
--
--
-_-
57,207
Green Roof
50%
1.08
amp #1 BMP #2 BMP#3
Wet Detention
Pond
no
Does BMP accept the outflow
no no
no
no
no
no no
no no
no__.. _.no.
Area treated Area treated
Area Treated
by BMP #2 that Is by BMP 93 that is
by BMP
not treated by BMP not treated by BMP,
(ft')
#1 #1 or #2
treated by BMPS
(ft') (ft')
342,612
135,163
163,159
..II
BMP 42 8MP83
wet netertinn
on another CitcFinaM7 lfw, Indicate which
no no
no no
one(s). (land use a
no
no
no
no
no
no
Area treated
no
no
Area treated
Area Treated
by BMP #2 that is
by BMP #3 that is
by BMP
not treated by BMP not
treated by BMPS
(k')
91
#1 or #2
(ft'1
(ft')
(ft')
___________________________ CATCHMENT4 ----------------------
amp #1 BMP 82 BMP#3
Wet Detention
Pond
ms entered below are in addition to the watershed areas tre
no do no
no do no
no no no
no
no
no
no
Area treated
no
no
Area treated
Area Treated
by BMP #2 that is
by BMP #3 that i!
by BMP
—treated by BMP
not treated by BM
(ft')
#1
#1 or #2
Cry Detention Pond
(ft'1
Ift'1
125,126-
_
--
--
-_-
57,207
Green Roof
50%
1.08
71,149
Level Spreader, Finer Strip
1 40%
1 1.20
20,259
BMP DETAILS
BMP
Volume Reduction ( %)
TN Effluent COncen.
(mg/LI
TP Effluent Conceit.
(mg/L)
Bloretention with lWS
50%
0.95
0.12
Biaretentian without PAS
35%
1.00
0.12
Cry Detention Pond
0%
1420
0.20
Grassed Swale
0%
1.21
0.26
Green Roof
50%
1.08
0.15
Level Spreader, Finer Strip
1 40%
1 1.20
0.15
Permeable Pavement'
0%
144
0.39
Sand Filter
5%
0.92
0.14
Water Harvesting
us er defined
1.08
0.15
Wet Detention Pond
10%
1.01
0.11
WetlaM
20%
1.08
0.12
it creating commercial paromg lo, t P eItl,,nt concentration=U.lb mg/L
amp #1 amp #2 BMP#3
I bycordrBwtiplicatchment(s).)
no no
no no
no
no
no
no
no
no
Area treated
no
no
Area treated
Area Treated
by BMP #2 that is
by BMP #3 that is
by BMP
not treated by BMP
not treated by BMPS
(ft')
#1
#1 or 42
(ft')
(ftz)
I t _ _.' —
I
10,949
242,001 0 0
242,001
33,542
727,562 0 0
727,562
644,785 _ -- - 0 0
644,785
i=IF!
0
------------- - - - - -- CATCHMENT6
amp 91 BMP 02 BMP#3
Area treated Area treated
Area Treated by BMP #2 that Is by BMP 93 that is
by BMP not treated by BMP not treated by BMP,
(ft') #1 #1.r #2
(ft) (ft:)
Total Land Use
Area Treated By
All BMPS
Ift'1
862,76]
368,0]4
447,436
0
0
136,]60
_
0
6,992
- _..
0..
_
0
0
0
0
0
0
0
0
0
0
0
0
—__ 0
_.. .. _ 0
0
0
— . 0
0
0
0
0
0
0
0
0
— - -4 -
_. 0
0
0
87,660
0 0 0
0
Allowable Total Land
use Area to be
Treated Based on
Post -Dev. Areas
(ft')
862,]67
368,0]4
590.366
p0
0
0
0
,ETgM
0
177,303
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.... _..
_ 00- _.
0
0
0
0
0
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8],660

WATERSHED SUMMARY Ver2.0
- REGION:
TOTAL DEVELOPMENT AREA (ft`):
Percent Impervious
( %)
Annual Runoff Volume
(c.f.)
Total Nitrogen EMC
(mg /L)
Total Nitrogen Loading
(lb /ac /yr)
Total Phosphorus EMC
(mg /L)
Total Phosphorus Loading
(lb /ac /yr)
Percent Difference Between:
3. Development Summary
Development: the EDGE
Prepared By: 1.E., El
Date: Mav 23. 2014
Piedmont
2,222,931
Pre - Development Conditions Post - Development Conditions
1.5% 65.5%
536,481 5,376,854
1.56 1.34
1.02 8.84
0.31 0.25
0.20 1.68
BMP SUMMARY Ver2.0
BMP1
Pre -Dev. &
Pre - Development &
Volume Reduction TN
Pond
Post -Dev. without BMPs
Post - Development with BMPs
Percent Impervious ( %)
5.56
-
64%
64%
Annual Runoff Volume (c.f.)
670,200
902%
806%
Total Nitrogen EMC (mg /L)
10%
-14%
-32%
Total Nitrogen Loading (lb /ac /yr)
(mg /L)
765%
513%
Total Phosphorus EMC (mg /L)
1.00
-18%
-58%
Total Phosphorus Loading (lb /ac /yr)
10.00
725%
283%
'Negative percent difference values indicate a decrease in
runoff volume, pollutant concentration or pollutant loading. Positive
values indicate an increase.
BMP SUMMARY Ver2.0
Catchment Outflow Nitrogen EMC (mg /L)
Catchment Outflow
6I6 Total Nitrogen (lb /ac /yr)
S
Percent Reduction in Nitrogen Load ( %)
i Catchment Outflow Phosphorus EMC
(mg /L)
Catchment Outflow
Total Phosphorus(Ib /ac /yr)
Percent Reduction in Phosphorus Load (%
CATCHMENT 1 CATCHMENT 2
BMP2 BMP3 BMP1 BMP2 BMP3
BMP1
CATCH MENT 6
BMP1 BMP2 BMP3
I°
Wet Deten
Volume Reduction TN
Pond
Total Area Treated
Post - Development w/ BMPs
(ac)
i.
5.56
-
Total Inflow Volume
(mg /L)
(c.f.)
670,200
Percent Volume Reduced
0.95
( %)
10%
Inflow Nitrogen EMC
(mg /L)
4,860,023
1.33
Total Inflow Nitrogen
1.00
0.12
1 (lb /ac /yr)
1111}
without IWS
10.00
Inflow Phosphorus EMC
1.06
I (mg /L)
0%
0.253
Total Inflow Phosphorus
6.26
Grassed Swale
• (lb /ac /yr)
1.21
1.91
d BMP Outflow
Green Roof
v, Nitrogen (Ibs /ac /yr)
7.07
p
BMP Outflow
Phosphorus(lbs /ac /yr)
0.87
j
Catchment Outflow Nitrogen EMC (mg /L)
Catchment Outflow
6I6 Total Nitrogen (lb /ac /yr)
S
Percent Reduction in Nitrogen Load ( %)
i Catchment Outflow Phosphorus EMC
(mg /L)
Catchment Outflow
Total Phosphorus(Ib /ac /yr)
Percent Reduction in Phosphorus Load (%
CATCHMENT 1 CATCHMENT 2
BMP2 BMP3 BMP1 BMP2 BMP3
CATCHMENT 3
BMP1 BMP2 BMP3
ention Pond
L4.80
99,371 f,
10%
1.34
L0.16
).254 -- --
1.93 - -
7.13
0.88 - -
-- ! -- 7.26 -- --
-- 0.89 -- --
BMPI
Wet Deter
Pond
6.78
798,37£
10%
1.33
9.80
0.253
1.86
6.90
0.85
I Return to Instructions
Return to Watershed Characteristics
Return to BMP Characteristics
Print Summary
LA I t.H M EN 1 4
BMP2
ion ---- ---- -I
BMP VOLUME REDUCTIONS /EFFLUENT CONCENTRATIONS
CATCH MENT 6
BMP1 BMP2 BMP3
I°
Volume Reduction TN
Effluent Concen.:
TP Effluent Concen.
Post - Development w/ BMPs
N
(mg /L)
(mg /L)
65.5%
BWSetention with
50%
0.95
0.12
4,860,023
Bioretention
35%
1.00
0.12
without IWS
1.06
Dry Detention Pond
0%
1.20
0.20
6.26
Grassed Swale
0%
1.21
0.26
0.13
Green Roof
50%
1.08
0.15
Level Spdr, Filter
0.78
Strip
40%
1.20
0.15
Permeable
Pavement*
0%
1.44
0.39
Post -Dev without BMPs &
Post -Dev with BMPs
Sand Filter
5%
0.92
0.14
0%
Water Harvesting
user defined
1.08
0.15
-10%
-21%
--
Wet Detention Pond
10%
1.01
0.11
-29%
-49
Wetland
20%
1.08
0.12
-54%
'if treating commercial
parking lot, TP effluent
concentration = 0.16 mg /L
CATCHMENT 3
BMP1 BMP2 BMP3
ention Pond
L4.80
99,371 f,
10%
1.34
L0.16
).254 -- --
1.93 - -
7.13
0.88 - -
-- ! -- 7.26 -- --
-- 0.89 -- --
BMPI
Wet Deter
Pond
6.78
798,37£
10%
1.33
9.80
0.253
1.86
6.90
0.85
I Return to Instructions
Return to Watershed Characteristics
Return to BMP Characteristics
Print Summary
LA I t.H M EN 1 4
BMP2
ion ---- ---- -I
! CATCHM ENT 5
BMP3 _ BMP1 BMP2 8MP3
- I
CATCH MENT 6
BMP1 BMP2 BMP3
I°

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