20050732 Ver 42_Calculations Submittal_20180125

vMCKIvt&crtEED
TO: NCDENR — Division of Water Resources
401 & Buffer Permitting Unit
512 N. Salisbury St.
Archdale Building - 9th floor
Raleigh, NC 27604
ATTENTION: Ms. Karen Higgins
LETTER OF TRANSMITTAL
DATE: January 15, 2018
PROJECT NO: 27.35-0165
TASK NO: EXP
RE: Briar Chapel — SD West
TRANSIVIlTTAL NO: 1
PAGE 1 OF 1
WE ARE SENDING: ❑ Originals ® Prints ❑ Shop Drawings ❑ Samples
❑ Specifications ® Calculations ❑ Other -
Quantity
Dwg
Rev.
Description
Status
No.
Issue Status Code: A. Preliminary B. Fabrication Only C. For Information D. Bid
E. Construction F. For Review & Comments G. For Approval H. See Remarks
REMARKS:
Karen,
Please find the enclosed documents for your review and approval. Please let us know if you have any
questions or comments. Thank you.
Cc:
1730 Varsity Drive, Suite 500 Raleigh, NC 27606 919/233-8091 Fax [phone]
Signed
McKIM & CREED, INC.
Gareth Avant, PE

vMCKIM&CREED ENGINEERS
S U R V E Y O R S
P L A N N E R S
January 15, 2018
Ms. Karen Higgins
512 N. Salisbury St.
Archdale Building - 9th floor
Raleigh, NC 27604
RE: Briar Chapel - SD West Phase 2
Ms. Higgins,
Please find enclosed the revised plans, revised calculations, revised supplement
forms and updated operation and maintenance agreement for BMP #26 at the SD
West commercial area in Briar Chapel (approved under DWR Permit # 05-
073206).
The intial design was based on a projected impervious number determined by
the initial site plan of the area. Based on new projections from the client and
requirements from the County, we are modifying the permit to provide
maximum flexibility for the site. Below is a summary of revisions made for this
submittal.
Summary of revisions:
RMP fflti
• Overall drainage area remains the same (19.76 acres).
Venture IV Building . Permitted impervious to be increased from 516,468 square feet to 602,546
Suite 500 square feet.
• Pond enlarged and raised 4' in elevation.
1 7 3 0 Varsity Drive • Updated operation and maintenance agreement has been provided based
on normal pool and bottom of pond elevation changes.
Raleigh, NC 27606
BMP #27
• Overall drainage area increased from 6.55 acres to 7.23 acres.
91 9.233.8091 . Permited impervious to be increased from 199,703 square feet to 251,814
Fax [phone] square feet.
• Footprint and grading of pond to remain the same.
www.mckimcreed.com

• Approved operation and maintenance agreement remains unchanged
based on pond revisions.
This letter is to formally request revised permit approval of the stormwater
management plan (Permit DWR# 05-0732v36 dated October 28, 2016) for the
enclosed plans in accordance with Water Quality Certification as issued by the
Division of Water Resources on January 11, 2008.
Please let me know if you have any questions on this. Thank you for your
assistance.
Sincerely,
McKIM & CREED, INC.
-'1&44604 av�
Gareth Avant, PE
Project Engineer
v� MCKIM&CREED

401 NARRATIVE &
SUPPORTING CALCULATIONS
Briar Chapel Development
SD West - Phase 2
Chatham County, North Carolina
January 15, 2018
Prepared for:
BRIAR:IZCHAPEC
Newland COMMUNITIES
NNP Briar Chapel, LLC
1342 Briar Chapel Parkway
Chapel Hill, North Carolina 27516
Prepared By:
MCKIM&CREED
1730 Varsity Drive, Suite 500
Raleigh, North Carolina 27606
Phone: [phone]
Fax: [phone]
M&C Project No. 02735-0165
`�15111l1lfff��i
�o
_ 036348
f l�f 11111 k11 ��

PROJECT DESCRIPITON
The purpose of the project is to construct basic infrastructure including water, sewer and
roadway to support future commercial and multi -use development within the SD West parcel of
Briar Chapel in Chatham County, North Carolina. Assumptions for impervious areas have been
made based on the latest approximations of the ultimate site layout. Those calculations have
been provided with this submittal.
Based on the conditions of the approved 401 Water Quality Certification, NCDENR-DEQ will
require runoff from the ultimate developed area to be captured and treated for 85% TSS
removal before being discharged into existing stream buffers. To meet this requirement, the
runoff from the general area of all SD West construction will be directed into one of 2 wet
detention ponds. Calculations for these facilities are included in this package and a drainage
area map relative to the future development has been included for reference.
SITE DESCRIPTION
The project area is approximately 29.20 acres of disturbed area located within the BC SD West
development area, which is at the intersection of US Highway 15/501 and Taylor Road in
Chatham County, North Carolina.
The site generally slopes away from a ridge located near the center of the project area, and
drains to the northwest and southeast accordingly. The slopes in the site range from 5-20% in
localized areas. A jurisdictional stream area has been located on the east side of the property
adjacent to US 15-501 as well as one in the far northwestern corner of the property. The
proposed clearing and grubbing respects the County required riparian buffers.
SOILS
According to the Chatham County Generalized Soil Survey, the soils located on the site are
classified as Wedowee sandy loam, 2 to 6 percent slopes (WeB); Wedowee sandy loam, 6 to 10
percent slopes (WeC), and Wedowee sandy loam, 10 to 15 percent slopes (WdD); and
Wedowee sandy loam, 15 to 25 percent slopes (WdE).
The following soil descriptions are associated with the soils found on the site:
We(X) - Wedowee sandy loam soils are often found in piedmont uplands, along ridges and
side slopes. Permeability is moderate and the soils are well drained. Soils have a low
shrink/swell potential. The seasonal high water is generally more than 6.0 feet below the
surface.

WET DETENTION DESIGN
The wet detention pond on this site has been designed to remove 90% of the total suspended
solids entering from the surrounding impervious drainage areas before discharging into the
adjacent stream buffer. The calculations provided with this package include all projected
future drainage areas that might be captured by the pond. Treated runoff will be dissipated by
a riprap outlet protection device before entering any stream buffers.
Design parameters were taken from the BMP manual, DEQ's design supplement forms, and NC
DEQ's Minimum Design Criteria for stormwater Control Measures based on criteria before the
latest 2017 changes (initial design and existing permit based on older minimum design criteria. In
addition to following minimum design criteria, the design also addresses the additional storms
discussed with Chatham County to provide peak runoff attenuation for commercial sites within
Briar Chapel (2 -year, 5 -year, 10 -year and 25 -year).
IMPERVIOUS PROJECTIONS
The table below is a summary of the projected impervious allocation provided in the overall
permanent design of the project.
BMP SUMMARY OF RESULTS
In order to meet the requirements of the development, two wet detention basins have been
designed based on an assumption of the full buildout condition of the site. A summary table is
provided below and the supporting calculations have been included with this submittal.
BMP #26
BMP #27
Overall Drainage area
19.76
7.23
Projected Impervious
13.83
5.78
Impervious %
70%
80 0
BMP SUMMARY OF RESULTS
In order to meet the requirements of the development, two wet detention basins have been
designed based on an assumption of the full buildout condition of the site. A summary table is
provided below and the supporting calculations have been included with this submittal.
BMP #26
1 -yr
2 -yr
5 -yr
10 -yr
25 -yr
100 -yr
Pre -Development
Discharge cfs
13.72
22.26
36.59
48.79
66.00
95.30
Post -Development
Controlled
6.12
8.57
13.76
33.95
65.96
95.49
Discharge cfs
Peak Water
Surface
475.06'
475.68'
476.58
476.95
477.34
477.87
Elevation ft

MAINTENANCE CONSIDERATIONS
The property owner shall be responsible for periodic inspection and maintenance of all
permanent stormwater management devices and shall adhere to conditions agreed upon by
the executed Operation and Maintenance agreements included with this submittal. Any
measure that fails to function as intended shall be repaired immediately.
BMP #27
1 -yr
2 -yr
5 -yr
10 -yr
25 -yr
100 -yr
Pre -Development
Discharge cfs
4.28
6.98
11.50
15.37
20.84
30.24
Post -Development
Controlled
2.42
3.59
4.83
8.33
20.74
41.23
Discharge cfs
Peak Water
Surface
458.32'
458.71
459.30
459.70
460.01
460.37
Elevation ft
MAINTENANCE CONSIDERATIONS
The property owner shall be responsible for periodic inspection and maintenance of all
permanent stormwater management devices and shall adhere to conditions agreed upon by
the executed Operation and Maintenance agreements included with this submittal. Any
measure that fails to function as intended shall be repaired immediately.

Maps

3 Soil Map—Chatham County, North Carolina
672300 672400 672500 672600 672700 672800 672900
35° 49'1" N
O
0
M
M
O
O
N
M
O
O
M
O
O
O
M
oO
T
M
O
M
O
O
n
T
M
35° 48'39'N
672300 672400 672500 672600 672700 672800
3
Map Scale: 1:4,900 if printed on A landscape (11" x 8.5") sheet.
g N Meters
0 50 100 200 300
Feet
0 200 400 800 1200
Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
uSDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
673000 673100 673200
a
673300
35° 49'1" N
O
M
N
M
S
N
U
M
8
N
M
O
O
N
M
O
O
U
M
O
M
O
n
N
M
35° 48'38" N
673300
3
v
672900 673000 673100 673200
8/21/2015
Page 1 of 3

50'
N%
90°-��
SSU
M111,111,11
j; ALL" R
A " E
, I I Wl, ", M�—q I
.W. 111, wok", molsao'EM, ME 1,
� ' C
m
r�e°!� l
untain� ( OAK
All
N
rdi
LYSTRA RO
I I pAll?rA!,
0
°ST�`FF6 is rington r

1970000 FEET 1980000 FEET
760000 FEET 79°6'0"W 795'30"W 79°5'0"W 79°4'30"W 760000 FEET
iiiP
mr
?o{ks L$an ng d _ ♦' if 15
'Y• r-
i+F �,�•, •��.k•. ° 'ti � r ,, ��,�.; .r;"fir �� !,'• �� -- - - - - _
.i:' i fly•rar .•� 4 �F'i V z' r- x
y�•p�- :��-i.f;•�rc"is ?y*_ ��F �_ 'ry +l i Z ir,• � 3. i t � Sne en. Rd ..V � x a� kk
•;t'= � -
]�' •; �y t 'IA1 y -�iti1 �r , 1II►IIC D .� l 11 -
•`�. � .� '�: 4'i'�.'j .r• 'iy '.f � ` �v i Stra li a .r -11t �•S'1 s
Sw"f] , 1 T �• ;' • a i�r!!! , �r �■ Y a s-
. ; f":
4 �• •
35°50'0"N �' zs r` ' ti i --ter•: _ �a t i+'it'i`�.• �_ .y } 35°50'0'N
Oki
��� syr ,►�' _
°.`�}►;�� ���/,,�'� �" '4 , � � � � ^J a � Cir L �N! � ► 5 aR y
9
L. Creek4sEd fGI of ♦ y ® ► ��'r`y
v :+ t r . � , alt ► "
XP
�— r. • �t �,.>; r BenK Ct[ ; . :;, .� in9 ' odor Rd `' � c
c �_�.�
58 ! `'rye
352 �J � f ..l,.�lt . .�:����� l ! •• r�, •� r�•���" - � � ���,� i ��`.•�I• ►, i� *� • a - :,
°h��srr ° L � s • ;.� P 8 en- aks ' . _ � Y -
All
ZONE AE r
Z3356ZIt
>e
i�10 P1,41
>f.•1 ri '�s T• r �r`..i ; `'�.� `..�� ,� dj" .�r•.a�`; i r � st •�A.
� t
i°'= � a - �� a'� - • � .�}.• Y' .-.]i�� -1 r• • _ ! S �� �':4 an . tip �j'
345. - - K :l �• _ _L LL > + [ - �.
- ��• fit 5 - + - •- i!y
N.
y�,•y:;'� ;•, • . p �.�:�'; `+,�; ;. Cie
J. y r Kt
: 3C"ti35"48'30"N ` 1 Ai
�
0-1'11 1-1ANI COL N l'Y
'=4'•,il .iw�_•_. Yr rt `' T..t��••i 'Y •s'� '!r :_ - ,«=, �:
i.,' . _y�...�+-ri �I�.•, :`+~f:�r?.,- :^',-P•, a,L.!s!ti,.� ?-r• >. �- _ • . qJI r,-- . _ - Ulvalily :-9\e �_-�lt,l �1 r.11 !t1�I t.7 Ar -- t *-.`4� �sr �y
--191— A ] IC-
it is
; j7]Z9t
r P ■ �i' �t i . i►`:; € - ,}WIL
15 :' lit l
ir
NL
•
`. . ;� a y,i.. • �+ 4 ,
s r•1;�: r 5?.r' '•_' •r r - n •`''.r-` �r •. - ate' •
•''1' - t _ y�' .may y.>. , ■ x 'r
�r�yy��� v ',i . _ 1�_��,{>� f: ���-T.'-. � �•. � j {'iL. .z�7 � r• _: *.L �: r � � s .r''�j`jG '` d .
R77 �Ilk M
-- .-.4 , Bre rChapel Pkwy T
moo f
!-OLI 'c dNILRd'� 'Z a Hubo HerndonR s>i �' '• r
a
.01
�: y , t ►
ins � �'Y• �� '- }n r.�x�' .A • , �, •, � �,. ,1 .. a
2rerP WhfspErin`gCrines MYipr+ R�1 �•r`• •' i + r` . Z
PI
v Carp r .r• r `ter'' � �r �. •, ,' �.'• ,1• �s •'ra'4:�•:; , •fir _ �
u ti A' h �• l
rl Rah _ -,�.- r s ~' Ar,• •• -YY - E r . •t .
e w y,
try• i - .. Vc&!.X' rri.P { . z .+�_ !, il+_�'.?�. .i:+:La Y• f - - - - - _ '
"Irv: y 4r, +-.Sr-'' is s ]'' 7 •. ,r. •"irp '�r r� �T i -
,r
a . .� _ r 1 {, a
: -f
35°49'0"N 35°49'0"N
_ _,�} ti���>.; �K � �. � '� • � ,'+` Sr n � `�ri�.,} _ �#a: f' #r ,' ',�-. • . .a • �nn�� -`•'.
X SAIL
44
39,0..9 2s2 � . t . �,�, r - , 4e• - 9 i 1' � !F� Ir. bs 7 dt
�' ik 1 `S� l •, •v•.T�.Yi•T.-.,r +� ,.. .r
y F # ,c , 4 t
e �ti 286 ,:a•f'
S , • s y _ , - , _- 4
La
kk
-. _....Andy `,s ore R •�� •��%� 'i�r' ' ■ , ti., i•'�• � - > .-w: � '� .-
d 750000 FEET
750000 FEET •79°6'0"W 795'30"W 795'0"W 79°4'30"W
1970000 FEET 1980000 FEET
_ r
FEW'S CQ10PERATING TECHNICAL PARTNER
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 to floodplain management to decrease the
costs associated with flooding. This is demonstrated by the State's commitment
to map flood hazard areas at the local level. As a part of this effort, the State of
North Carolina has joined in a Cooperating Technical State agreement with
FEMA to produce and maintain this digital FIRM.
FLOOD HAZARD INFORMATION NOTES TO USERS SCALE
SEE FIS REPORT FOR ZONE DESCRIPTIONS AND INDEX MAP
THE INFORMATION DEPICTED ON THIS MAP AND SUPPORTING
DOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMAT AT
HTTP:// FR 1 S. N C.G 0V/ FR IS
Without Base Flood Elevation (BFE)
Zayre A,V, A99
With BFE or Depth -,ne AE, AC, AH, VE, AR
SPECIAL FLOOD
HAZARD AREAS
Regulatory Floodway
For information and questions about this map, available products associated with this FIRM including
historic versions of this FIRM, how to order products or the National Flood Insurance Program in general,
please call the FEMA Map Information eXchange at 1 -877 -FEMA -MAP (1-877-336-2627) or visit the FEMA Map
Service Center website at http:tfmsc.fema.gov. An accompanying Flood Insurance Study report, Letter of Map
Revision (LOMB) or Letter of Map Amendment (LOMA) revising portions of this panel, and digital versions of this
FIRM may be available. Visit the North Carolina Floodplain Mapping Program website at hftp://www-ncfloodmaps.corr
or contact the FEMA Map Service Center.
Communities annexing land on adjacent FIRM panels must obtain a current copy of the adjacent panel as well as
the current FIRM Index. These may be ordered directly from the Map Service Center at the number listed above.
For community and countywide map dates refer to the Flood Insurance Study report for this jurisdiction.
To determine if flood insurance is available in the community, contact your Insurance agent or call the National
Flood Insurance Program at 1-$00-638-6620.
Flood Insurance Study (FIS) means an examination, evaluation, and determination of flood hazards, corresponding
water surface elevations, flood hazard risk zones, and other flood data in a community issued by the North Carolina
Floodplain Mapping Program (NCFMP). The Flood Insurance Study (FIS) is comprised of the following products
used together: the Digital Flood Hazard Database, the Water Surface Elevation Rasters, the digitally derived,
autogenerated Flood Insurance Rate Map and the Flood Insurance Survey Report. A Flood Insurance Survey is a
compilation and presentation of flood risk data for specific watercourses, lakes, and coastal flood hazard areas within
a community. This report contains detailed flood elevation data, data tables and FIRM indices. When a flood study is
completed for the NFIP, the digital information, reports and maps are assembled into an FIS. Information shown on
this FIRM is provided in digital format by the NCFMP. Base map information shown on this FIRM was provided in
digital format by the NCFMP. The source of this information can be determined from the metadata available in the
digital FLOOD database and in the Technical Support Data Notebook (TSDN).
ACCREDITED LEVEE NOTES TO USERS: If an accredited levee note appears on this panel check with your local
community to obtain more information, such as the estimated level of protection provided (which may exceed the
1 -percent -annual -chance level) and Emergency Action Plan, on the levee system(s) shown as providing protection,
To mitigate flood risk in residual risk areas, property owners and residents are encouraged to consider flood
insurance and floodproofing or other protective measures. For more information on flood insurance, interested
parties should visit the FEMA Website at http:llwww.fema.govlbusiness/nfip/index.shtm-
PROVISIONALLY ACCREDITED LEVEE NOTES TO USERS: If a Provisionally Accredited Levee (PAL) note
appears on this panel, check with your local community to obtain more information, such as the estimated level of
protection provided (which may exceed the 1 -percent -annual -chance level) and Emergency Action Plan, on the
levee system(s) shown as providing protection. To maintain accreditation, the levee owner or community is
required to submit the data and documentation necessary to comply with Section 65.10 of the NFIP regulations.
If the community or owner does not provide the necessary data and documentation or if the data and documentation
provided indicates the levee system does not comply with Section 65.10 requirements, FEMA will revise the flood
hazard and risk information for this area to reflect de -accreditation of the levee system. To mitigate flood risk in
residual risk areas, property owners and residents are encouraged to consider flood insurance and floodproofing
or other protective measures. For more information on flood insurance, interested parties should visit the FEMA
Website at http:l/www.fema.gov/business/nfip/index.shtm.
LIMIT OF MODERATE WAVE ACTION NOTES TO USERS: For some coastal flooding zones the AE Zone
category has been divided by a Limit of Moderate Wave Action (LiMWA). The LiMWA represents the approximate
landward limit of the 1.5 -foot breaking wave. The effects of wave hazards between the VE Zone and the LiMWA
(or between the shoreline and the LiMWA for areas where VE Zones are not identified) will be similar to, but less
severe than those in the VE Zone.
Limit of Moderate Wave Action (LiMWA)
COASTAL BARRIER RESOURCES SYSTEM (CBRS) NOTE
This map may include approximate boundaries of the CBRS for informational purposes only. Flood insurance is not
available within CBRS areas for structures that are newly built or substantially improved on or after the dates)
indicated on the map. For more information see http:tlwww.fws.govlcbra, the FIS Report, or call the U.S. Fish
and Wildlife Service Customer Service Center at 1 -800 -344 -WILD.
CBRS Area \ : \ \ Otherwise Protected Area
Map Projection:
North Carolina State Plane Projection Feet (Zone 3200)
Datum: NAD 1983 (Horizontal), NAVD 1988 (Vertical)
1 inch = 500 feet 1:6,000
0 250 500 1,000
Feet
Meters
0 75 150 300
PANEL LOCATOR
Guilford
DIS,
Alamance
8746 1 8766
i1 9125197351974
8724 it 8744 I 8764 I 8784 9704 9724 9734 974
i
0.2% Annual Chance Flood Hazard, Areas
8763
of 1% Annual Chance Flood with Average
Depth Less Than One Foot or With Drainage
Areas of Less Than One Square Mile zone x
9753
Future Conditions 1% Annual
8742
Chance Flood Hazard zone x
OTHER AREAS OF
Area with Reduced Flood Risk due to Levee
FLOOD HAZARD
See Notes Zone x
OTHER
Areas Determined to be Outside the
AREAS
0.2% Annual Chance Floodplain zone x
------------- Channel, Culvert, or Storm Sewer
8762
Accredited or Provisi o n a I ly Accred ited
GENERAL
Levee, Dike, or Flo odwall
STRUCTURES
{ I l I I{ I l I I r I l Non -accredited Levee, Dike, or Floodwall
9752
BM5510 X North Carolina Geodetic Survey bench mark
8741
BM55100 National Geodetic Survey bench mark
8761
BM5510<8> Contractor Est. NCFMP Survey bench mark
ofz 1.8-2 Cross Sections with 1% Annual Chance
9721973197419
Water Surface Elevation (BFE)
- - - - - Coastal Transect
8720 I
— - - - - - Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
OTHER
Limit of Study
FEATURES
Jurisdiction Boundary
For information and questions about this map, available products associated with this FIRM including
historic versions of this FIRM, how to order products or the National Flood Insurance Program in general,
please call the FEMA Map Information eXchange at 1 -877 -FEMA -MAP (1-877-336-2627) or visit the FEMA Map
Service Center website at http:tfmsc.fema.gov. An accompanying Flood Insurance Study report, Letter of Map
Revision (LOMB) or Letter of Map Amendment (LOMA) revising portions of this panel, and digital versions of this
FIRM may be available. Visit the North Carolina Floodplain Mapping Program website at hftp://www-ncfloodmaps.corr
or contact the FEMA Map Service Center.
Communities annexing land on adjacent FIRM panels must obtain a current copy of the adjacent panel as well as
the current FIRM Index. These may be ordered directly from the Map Service Center at the number listed above.
For community and countywide map dates refer to the Flood Insurance Study report for this jurisdiction.
To determine if flood insurance is available in the community, contact your Insurance agent or call the National
Flood Insurance Program at 1-$00-638-6620.
Flood Insurance Study (FIS) means an examination, evaluation, and determination of flood hazards, corresponding
water surface elevations, flood hazard risk zones, and other flood data in a community issued by the North Carolina
Floodplain Mapping Program (NCFMP). The Flood Insurance Study (FIS) is comprised of the following products
used together: the Digital Flood Hazard Database, the Water Surface Elevation Rasters, the digitally derived,
autogenerated Flood Insurance Rate Map and the Flood Insurance Survey Report. A Flood Insurance Survey is a
compilation and presentation of flood risk data for specific watercourses, lakes, and coastal flood hazard areas within
a community. This report contains detailed flood elevation data, data tables and FIRM indices. When a flood study is
completed for the NFIP, the digital information, reports and maps are assembled into an FIS. Information shown on
this FIRM is provided in digital format by the NCFMP. Base map information shown on this FIRM was provided in
digital format by the NCFMP. The source of this information can be determined from the metadata available in the
digital FLOOD database and in the Technical Support Data Notebook (TSDN).
ACCREDITED LEVEE NOTES TO USERS: If an accredited levee note appears on this panel check with your local
community to obtain more information, such as the estimated level of protection provided (which may exceed the
1 -percent -annual -chance level) and Emergency Action Plan, on the levee system(s) shown as providing protection,
To mitigate flood risk in residual risk areas, property owners and residents are encouraged to consider flood
insurance and floodproofing or other protective measures. For more information on flood insurance, interested
parties should visit the FEMA Website at http:llwww.fema.govlbusiness/nfip/index.shtm-
PROVISIONALLY ACCREDITED LEVEE NOTES TO USERS: If a Provisionally Accredited Levee (PAL) note
appears on this panel, check with your local community to obtain more information, such as the estimated level of
protection provided (which may exceed the 1 -percent -annual -chance level) and Emergency Action Plan, on the
levee system(s) shown as providing protection. To maintain accreditation, the levee owner or community is
required to submit the data and documentation necessary to comply with Section 65.10 of the NFIP regulations.
If the community or owner does not provide the necessary data and documentation or if the data and documentation
provided indicates the levee system does not comply with Section 65.10 requirements, FEMA will revise the flood
hazard and risk information for this area to reflect de -accreditation of the levee system. To mitigate flood risk in
residual risk areas, property owners and residents are encouraged to consider flood insurance and floodproofing
or other protective measures. For more information on flood insurance, interested parties should visit the FEMA
Website at http:l/www.fema.gov/business/nfip/index.shtm.
LIMIT OF MODERATE WAVE ACTION NOTES TO USERS: For some coastal flooding zones the AE Zone
category has been divided by a Limit of Moderate Wave Action (LiMWA). The LiMWA represents the approximate
landward limit of the 1.5 -foot breaking wave. The effects of wave hazards between the VE Zone and the LiMWA
(or between the shoreline and the LiMWA for areas where VE Zones are not identified) will be similar to, but less
severe than those in the VE Zone.
Limit of Moderate Wave Action (LiMWA)
COASTAL BARRIER RESOURCES SYSTEM (CBRS) NOTE
This map may include approximate boundaries of the CBRS for informational purposes only. Flood insurance is not
available within CBRS areas for structures that are newly built or substantially improved on or after the dates)
indicated on the map. For more information see http:tlwww.fws.govlcbra, the FIS Report, or call the U.S. Fish
and Wildlife Service Customer Service Center at 1 -800 -344 -WILD.
CBRS Area \ : \ \ Otherwise Protected Area
Map Projection:
North Carolina State Plane Projection Feet (Zone 3200)
Datum: NAD 1983 (Horizontal), NAVD 1988 (Vertical)
1 inch = 500 feet 1:6,000
0 250 500 1,000
Feet
Meters
0 75 150 300
PANEL LOCATOR
Guilford
DIS,
Alamance
8746 1 8766
i1 9125197351974
8724 it 8744 I 8764 I 8784 9704 9724 9734 974
i
8763
8773
9743
9753
8722 1
8742
8782
9702
9722
8762
8772
9742
9752
8741
8751
8761
8771
9721973197419
51
8720 I
8780
9700
8740
8750
8760
8770
9720
9730
9740
9750
8528; I 8648 I 8668 I 8688 I 9608 I 9628 1 9648
8656 1 8686 1 9506 1 9626
8544 1 8664
4'
Moore
F
1419624
Durham
764 9774 9784 0704
724
763 9773 0703 0713
9782 '
762 9772 0702 0712
r
761 9771 0701 D711
97'80
760 9770 0700 0710
cco acro ❑cQa ecoa 1 Wake
647 !f[_7
646
645
Harriett
0626
0624
NORTH CAROLINA FLOODPLAIN MAPPING PROGRAM
NATIONAL FLOOD INSURANCE PROGRAM
cc FLOOD INSURANCE RATE MAP
NORTH CAROLINA VART
0 � M
CL PANEt_9775
❑��t'iHD 5EG�ir
(1) FEMA
cc Panel Contains:
I COMMUNITY CID PANEL SUFFIX
Iti CHATHAM COUNTY 370299 9775 K
!i~ U)
0
0
LL
0
VERSION NUMBER
2.3.3.2
MAP NUMBER
3710977500K
MAP REVISED
November 17, 2017

rLMI Dr',. V0,'rv. 1ZYr I I / I / / i
PLAT BK. 2002, PG. 512
NIF
COUNTY OF CHATHAM
DB. 460, PG. 669
V A V 1 \
�oe
— — — — — — — — — —— — — — — V
���\\
s,
/ DRAINAGE AREA: 7.23 ACRES I y0 �������� \ / ♦ \
\ \ I 807o IMPERVIOUS
\ /
/ 9 I
�A
1 � �49 , \ \ ,
/ / 9
BMP #26 DRAINAGE AREA
BMP #27 DRAINAGE AREA
I /
I /
I /
I
I /
I /
I /
I /
I /
/—T
I \ \
I / \
I /
/
1 /
I /
I /
I /
1 /
I /
I /
1 /
I
/
/
�0 .-
\
(AR
0
yR
R
1\\ 40* / I
� I
BMP #26
/ DRAINAGE AREA: 19.76 ACRES �%
70% IMPERVIOUS
/
472.50
—1-11 go 0
10 '.1,70"0'00
SEAL 1
SEAL 1
R
/ /I
.41
r
r / /
/.I l000l
10*1
Ile
0rW-
' / // /// // / // / /- // 80 0 80 160
i
SCALE: 1"=80' (Horiz.)
v
v &CREED
1730 Varsity Drive, Suite 500
Raleigh, North Carolina 27606
Phone: [phone], Fax: [phone]
F-1222
www.mckimcreed.com
BRIAR
CHAPEL
by
Newland COMMUNITIES
BRIAR CHAPEL
SD WEST - PHASE 2
CHATHAM COUNTY, NORTH CAROLINA
BRIAR CHAPEL - SD WEST
DRAINAGE AREA MAP
JANUARY 15, 2018
DATE: SEPTEMBER 30, 2016
MCE PROJ. #
02735-0165
DRAWN
BSS
DESIGNED
BSS
CHECKED
GCA
8
STORMWATER BMP REVISIONS
2018.01.15
7
REVISED PER ADDITIONAL ROADWAY CHANGES
2017.08.18
6
REVISED PER ADDITIONAL ROADWAY CHANGES
2017.08.09
5
REVISED PER STORM DRAIN REVISIONS
2017.07.11
4
REVISED PER ROADWAY LAYOUT CHANGES
2017.06.30
3
REVISED PER ADDITIONAL DISTURBED AREA
2017.03.13
2
REVISED PER COMMENTS FROM NC PWSS
2016.11.22
1
ISSUED FOR PERMITTING
2016.09.30
REV.NO.
DESCRIPTIONS
DATE
REVISIONS
SEAL 1
SEAL 1
R
/ /I
.41
r
r / /
/.I l000l
10*1
Ile
0rW-
' / // /// // / // / /- // 80 0 80 160
i
SCALE: 1"=80' (Horiz.)
v
v &CREED
1730 Varsity Drive, Suite 500
Raleigh, North Carolina 27606
Phone: [phone], Fax: [phone]
F-1222
www.mckimcreed.com
BRIAR
CHAPEL
by
Newland COMMUNITIES
BRIAR CHAPEL
SD WEST - PHASE 2
CHATHAM COUNTY, NORTH CAROLINA
BRIAR CHAPEL - SD WEST
DRAINAGE AREA MAP
JANUARY 15, 2018
DATE: SEPTEMBER 30, 2016
MCE PROJ. #
02735-0165
DRAWN
BSS
DESIGNED
BSS
CHECKED
GCA
PRO]. MGR.
CHS
SCALE
HORIZONTAL:
VERTICAL:
STATUS: FINAL DRAWINGS REVISION
FOR REVIEW PURPOSES ONLY 8

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin Operation and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
❑ does ❑ does not incorporate a vegetated filter at the outlet.
This system (check one):
❑ does ❑ does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
— Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
— No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
— Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
— If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
— Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element:
Potentialproblem:
How I will remediate theproblem:
The entire BMP
Trash/ debris is present.
Remove the trash/ debris.
The perimeter of the wet
Areas of bare soil and/or
Regrade the soil if necessary to
detention basin
erosive gullies have formed.
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
Vegetation is too short or too
Maintain vegetation at a height of
long.
approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 1 of 4

Wet Detention Pond #26
Design

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The inlet device: pipe or
The pipe is clogged.
Unclog the pipe. Dispose of the
swale
sediment off-site.
The pipe is cracked or
Replace the pipe.
otherwise damaged.
Erosion is occurring in the
Regrade the swale if necessary to
swale.
smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design depth for
possible. Remove the sediment and
sediment storage.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred.
Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
revent future erosion problems.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf
Best professional practices
Prune according to best professional
show that pruning is needed
practices
to maintain optimal plant
health.
Plants are dead, diseased or
Determine the source of the
dying.
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design sediment
possible. Remove the sediment and
storage depth.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over
Consult a professional to remove
50% of the area.
and control the algal growth.
Cattails, phragmites or other
Remove the plants by wiping them
invasive plants cover 50% of
with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 2 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The embankment
Shrubs have started to grow
Remove shrubs immediately.
on the embankment.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
A tree has started to grow on
Consult a dam safety specialist to
the embankment.
remove the tree.
An annual inspection by an
Make all needed repairs.
appropriate professional
shows that the embankment
needs repair. if applicable)
The outlet device
Clogging has occurred.
Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged
Repair or replace the outlet device.
The receiving water
Erosion or other signs of
Contact the local NC Division of
damage have occurred at the
Water Quality Regional Office, or
outlet.
the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 9.00 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 4.50 feet in the forebay, the sediment
shall be removed.
Sediment Removal
Bottom
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 472.50
468.0 Pe mann Pool
• - - - - - - - - - - - - - - - - - Volume Sediment Removal Elevation 463.50
- Volume
467.0 ft Min. -------------------------------------------- ------
Sediment Bottom Elevation 461.50 1 -ft n
Storage Sedimer
Storage
FOREBAY MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.4 Page 3 of 4

Permit Number:
(to be provided by DWQ)
I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project narne:Briar Chapel - SD West
BMP drainage area number: l - Wet Detention Pond #26
Print name:Lee Bowman
Title:Senior Project Manager
Address: 1342 Briar Chapel Parkway, Chapel Hill NC 27516
Phone:to!i 9) 9_51_-0712
Signature:
Date: j
Note: The legally responsible party should not be a homeowners association unless more than 50/0 of
the lots have been sold and a resident of the subdivision has been named the president.
I. a Notary Public for the State of
, County ofL)t&yYtr, do hereby certify that
rCl
GL persomilly appeared before me this
day ofd, and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal,
p►otary r
IC bl�L
% 3
SEAL
My commission expiresO_ (012,512OW
Form SW401-Wet Detention Basin O&M-Rev.4 Page 4 of 4

Permit No.
Red triangles at the upper right hand corner indicate design comments
Please complete the yellow shaded items.
AIMP—AA
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
Project name
Contact person
Phone number
Date
Drainage area number
Site Characteristics
Drainage area
Impervious area, post -development
% impervious
Design rainfall depth
Storage Volume: Non -SA Waters
Minimum volume required
Volume provided
Storage Volume: SA Waters
1.5" runoff volume
Pre -development 1 -yr, 24 -hr runoff
Post -development 1 -yr, 24 -hr runoff
Minimum volume required
Volume provided
Peak Flow Calculations
Is the pre/post control of the lyr 24hr storm peak flow required?
1 -yr, 24 -hr rainfall depth
Rational C, pre -development
Rational C, post -development
Rainfall intensity: 1 -yr, 24 -hr storm
Pre -development 1 -yr, 24 -hr peak flow
Post -development 1 -yr, 24 -hr peak flow
Pre/Post 1 -yr, 24 -hr peak flow control
Elevations
Temporary pool elevation
Permanent pool elevation
SHWT elevation (approx. at the perm. pool elevation)
Top of 1 Oft vegetated shelf elevation
Bottom of 1 Oft vegetated shelf elevation
Sediment cleanout, top elevation (bottom of pond)
Sediment cleanout, bottom elevation
Sediment storage provided
Is there additional volume stored above the state -required temp. pool?
Elevation of the top of the additional volume
919.233.8091
Briar Chapel - SD West
Gareth Avant, PE
9/30/2016, REVISED 01/15/2018
1 - Wet Pond #26
860,780 ft2
602,546 ft2
70.00 %
1.0 in
48,778 ft3
52,146 ft3
ft3
ft3
ft3
ft3
ft3
OK
(to be provided by DWQ)
O�O� W ATF9QG
li
y
o
OK, volume provided is equal to or in excess of volume required.
Y (Y or N)
3.0 in
0.40 (unitless)
0.76 (unitless)
0.13 in/hr OK
12.87 ft3/sec
47.65 ft3/sec
34.78 ft3/sec
474.20 fmsl
472.50 fmsl
fmsl
473.00 fmsl
472.00 fmsl
Data not needed for calculation option 41, but OK if provided.
463.50 fmsl
461.50 fmsl
Data not needed for calculation option 41, but OK if provided.
2.00 ft
Y (Y or N)
474.2 fmsl
OK
Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 1 of 2

Permit No.
Surface Areas
Area, temporary pool
32,736 ft2
OK
Area REQUIRED, permanent pool
26,684 ft2
OK
SADA ratio
3.10 (unitless)
OK
Area PROVIDED, permanent pool, Apen-pool
26,973 ft2
OK
Area, bottom of 1 Oft vegetated shelf, Abot shelf
23,883 ft2
OK
Area, sediment cleanout, top elevation (bottom of pond), AW_,nd
2,537 ft2
OK
Volumes
1.0 ft
OK
Volume, temporary pool
52,146 ft3
OK
Volume, permanent pool, Vpenpool
119,762 ft3
OK
Volume, forebay (sum of forebays if more than one forebay)
25,428 ft3
OK
Forebay % of permanent pool volume
21.2% %
OK
SADA Table Data
Design TSS removal
90 %
Coastal SADA Table Used?
N (Y or N)
Mountain/Piedmont SADA Table Used?
Y (Y or N)
SADA ratio
3.10 (unitless)
Average depth (used in SADA table):
Calculation option 1 used? (See Figure 10-2b)
Y (Y or N)
Volume, permanent pool, Vpenpool
119,762 ft3
Area provided, permanent pool, Aperm_pool
26,973 ft2
Average depth calculated
4.44 ft
OK
Average depth used in SA/DA, deV, (Round to nearest 0.5ft)
4.5 ft
OK
Calculation option 2 used? (See Figure 10-2b)
N (Y or N)
Area provided, permanent pool, Aperm_pool
26,973 ft2
Area, bottom of 1 Oft vegetated shelf, Abot shelf
23,883 ft2
Area, sediment cleanout, top elevation (bottom of pond), Abot-pond
2,537 ft2
"Depth" (distance b/w bottom of 1Oft shelf and top of sediment)
8.50 ft
Average depth calculated
ft
Average depth used in SA/DA, deV, (Round to nearest 0.5ft)
ft
Drawdown Calculations
Drawdown through orifice?
Y (Y or N)
Diameter of orifice (if circular)
3.50 in
Area of orifice (if -non -circular)
int
Coefficient of discharge (CD)
0.60 (unitless)
Driving head (Ho)
0.56 ft
Drawdown through weir?
N (Y or N)
Weir type
(unitless)
Coefficient of discharge (CW)
(unitless)
Length of weir (L)
ft
Driving head (H)
ft
Pre -development 1 -yr, 24 -hr peak flow
13.72 ft3/sec
Post -development 1 -yr, 24 -hr peak flow
6.12 ft3/sec
Storage volume discharge rate (through discharge orifice or weir)
0.22 ft3/sec
Storage volume drawdown time
2.50 days
OK, draws down in 2-5 days.
Additional Information
Vegetated side slopes
3 :1
OK
Vegetated shelf slope
10 :1
OK
Vegetated shelf width
10.0 ft
OK
Length of flowpath to width ratio
3 :1
OK
Length to width ratio
1.5 :1
OK
Trash rack for overflow & orifice?
Y (Y or N)
OK
Freeboard provided
1.0 ft
OK
Vegetated filter provided?
N (Y or N)
OK
Recorded drainage easement provided?
Y (Y or N)
OK
Capures all runoff at ultimate build -out?
Y (Y or N)
OK
Drain mechanism for maintenance or emergencies is:
Pump providW by owner
(to be provided by DWQ)
Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 2 of 2

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin Operation and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
❑ does ❑ does not incorporate a vegetated filter at the outlet.
This system (check one):
❑ does ❑ does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
— Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
— No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
— Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
— If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
— Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element:
Potentialproblem:
How I will remediate theproblem:
The entire BMP
Trash/ debris is present.
Remove the trash/ debris.
The perimeter of the wet
Areas of bare soil and/or
Regrade the soil if necessary to
detention basin
erosive gullies have formed.
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
Vegetation is too short or too
Maintain vegetation at a height of
long.
approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 1 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The inlet device: pipe or
The pipe is clogged.
Unclog the pipe. Dispose of the
swale
sediment off-site.
The pipe is cracked or
Replace the pipe.
otherwise damaged.
Erosion is occurring in the
Regrade the swale if necessary to
swale.
smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design depth for
possible. Remove the sediment and
sediment storage.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred.
Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
revent future erosion problems.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf
Best professional practices
Prune according to best professional
show that pruning is needed
practices
to maintain optimal plant
health.
Plants are dead, diseased or
Determine the source of the
dying.
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design sediment
possible. Remove the sediment and
storage depth.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over
Consult a professional to remove
50% of the area.
and control the algal growth.
Cattails, phragmites or other
Remove the plants by wiping them
invasive plants cover 50% of
with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 2 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The embankment
Shrubs have started to grow
Remove shrubs immediately.
on the embankment.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
A tree has started to grow on
Consult a dam safety specialist to
the embankment.
remove the tree.
An annual inspection by an
Make all needed repairs.
appropriate professional
shows that the embankment
needs repair. if applicable)
The outlet device
Clogging has occurred.
Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is damaged
Repair or replace the outlet device.
The receiving water
Erosion or other signs of
Contact the local NC Division of
damage have occurred at the
Water Quality Regional Office, or
outlet.
the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads 9.00 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 4.50 feet in the forebay, the sediment
shall be removed.
Sediment Removal
Bottom
BASIN DIAGRAM
(fill in the blanks)
Permanent Pool Elevation 472.50
468.0 Pe mann Pool
• - - - - - - - - - - - - - - - - - Volume Sediment Removal Elevation 463.50
- Volume
467.0 ft Min. -------------------------------------------- ------
Sediment Bottom Elevation 461.50 1 -ft n
Storage Sedimer
Storage
FOREBAY MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.4 Page 3 of 4

Permit Number:
(to be provided by DWQ)
I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project name:Briar Chapel - SD West
BMP drainage area number:.1 - Wet Detention Pond #26
Print name:Lee Bowman
Title:Senior Project Manager
Address: 1342 Briar Chapel Parkway, Chapel Hill, NC 27516
Phone: [phone]
Signature:
Date:
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
I, , a Notary Public for the State of
, County of , do hereby certify that
personally appeared before me this
day of , and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal,
SEAL
My commission expires
Form SW401-Wet Detention Basin O&M-Rev.4 Page 4 of 4

WATER QUALITY POND #26 CALCULATIONS
Project Name
15-501 BMP (West)
Project Number
2735-0165
Date
September 30, 2016
3rd revision
2nd revision
1 st revision
15 -Jan -18

Water Quality Pond Drainage Area Data
Project 15-501 BMP (West)
Project No. 2735-0165
Date January 15. 2018
Total site area 860,780 square feet = 19.76 acres
Impervious areas
Drainage area to pond
Existing Proposed Change
[sf] [sf] [sf]
Other Drainage Area
Existing Proposed
[sf] [sf]
On-site buildings (BUA)
0
602,546
602,546
0
0
On-site streets
0
0
0
0
0
On-site alleys
0
0
0
0
0
On-site sidewalks
0
0
0
0
0
On-site future (open space)
0
0
0
0
0
Off-site future development
0
0
0
0
0
Contingenc 1
0
1 0 1
0 1
0
0
Total Impervious 1
1 602,546 1
602,546 1
0
f"
Non -impervious areas
Drainage area to pond
Existing Proposed Change
[sf] [sf] [sf]
Other Drainage Area
Existing Proposed
[sf] [sf]
On-site grass/landscape
0
258,234
258,234
0
0
On-site woods
0
0
0
0
0
Other undeveloped
0
0
0
0
0
Total off-site non -impervious
0
0
0
0
0
Total non -impervious
0
258,234
258,23x'
0
0
Total Drainage Area 860,780 860,780 0 0
Percent Impervious 0.0 70.0 70.0 n/a
2017.06.29.15-501. BM P.xls
Site Drainage Area Data Page 2 of 18 Printed 1/15/2018 9:29 AM

Water Quality Pond Surface Area Calculations
Project 15-501 BMP (West)
Project No. 2735-0165
Date January 15, 2018
Total on-site drainage area to pond 860,780 square feet
Total impervious area in drainage area 602,546 square feet
Average water depth of basin at normal pool 4.5 feet
Location of site Chatham County
Site region Piedmont
% Impervious cover 70.0 percent
If the site is in a coastal area, will a vegetative filter be used? n/a
Surface Area/Drainage Area Ratios:
For a site in the Piedmont (85%)
2.2 percent
For a site in the Piedmont (90%)
3.1 percent
For a site in a Coastal County w/ Vegetative Filter
4.1 percent
For a site in a Coastal County w/out Vegetative Filter
5.5 percent
Required surface area of pond:
For a site in the Piedmont (85%)
19,240.0 square feet
For a site in the Piedmont (90%)
26,260.0 square feet
For a site in a Coastal County w/ Vegetative Filter
35,300.0 square feet
For a site in a Coastal County w/out Vegetative Filter
47,350.0 square feet
Notes:
2017.06.29.15-501. B M P. x l s
Pond Surface Area Calcs Page 3 of 18 Printed 1/15/2018 9:29 AM

Water Quality Pond Stormwater Runoff Volume Calculations
Project 15-501 BMP (West)
Project No. 2735-0165
Date January 15, 2018
Drainage area
860,780
square feet
Impervious area
602,546
square feet
Rainfall depth
1.00
inches
Percent Impervious
70.0
percent
R(v)=0.05+0.009*(Percent
impervious)
Runoff coefficient - R(v)
0.68
in/in
Runoff volume=(Design rainfall)*(R(v))*(Drainage area)
Runoff volume 48,777.5 cubic feet
Notes:
2017.06.29.15-501. B M P. x l s
Runoff Volume Calcs Page 4 of 18 Printed 1/15/2018 9:29 AM

Project
Project No.
Date
15-501 BMP (West)
2735-0165
January 15, 2018
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Temporary Pool
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
472.5
0
26,972.0
0.619
26,972.0
0.6
0.0
0.0
0.0
0.0
473
0.5
30,316.0
0.696
30,316.0
0.1
14,322.0
0.3
14,322.0
0.3
474
1.5
32,321.0
0.742
32,321.0
0.0
31,318.5
0.7
45,640.5
1.0
474.2
1.7
32,736.0
0.752
32,736.0
0.0
6,505.7
0.1
52,146.2
0.9
475
2.5
34,358.0
0.789
34,358.0
0.0
26,837.6
0.6
78,983.8
0.8
476
3.5
36,454.0
0.837
36,454.0
0.0
35,406.0
0.8
114,389.8
1.4
477
4.5
38,610.0
0.886
38,610.0
0.0
37,532.0
0.9
151,921.8
1.7
478
5.5
40,898.0
0.939
40,898.0
0.1
39,754.0
0.9
191,675.8
1.8
479
6.5
43,204.0
0.992
43,204.0
0.1
42,051.0
1.0
233,726.8
1.9
2017.06.29.15-501. BM P.xls
Stage Storage (Temp Pool) Page 5 of 18 Printed 1/15/2018 9:29 AM

Project
Project No.
Date
15-501 BMP (West)
2735-0165
January 15, 2018
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Permanent Pool
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
461.5
0
2,551.0
0.059
2,551.0
0.1
0.0
0.0
0.0
0.0
462
0.5
2,938.0
0.067
387.0
0.0
1,372.3
0.0
1,372.3
0.0
463
1.5
3,791.0
0.087
853.0
0.0
3,364.5
0.1
4,736.8
0.1
464
2.5
4,729.0
0.109
938.0
0.0
4,260.0
0.1
8,996.8
0.2
465
3.5
5,754.0
0.132
1,025.0
0.0
5,241.5
0.1
14,238.3
0.2
466
4.5
6,870.0
0.158
1,116.0
0.0
6,312.0
0.1
20,550.3
0.3
467
5.5
9,889.0
0.227
3,019.0
0.1
8,379.5
0.2
28,929.8
0.3
468
6.5
12,033.0
0.276
2,144.0
0.0
10,961.0
0.3
39,890.8
0.4
469
7.5
14,315.0
0.329
2,282.0
0.1
13,174.0
0.3
53,064.8
0.6
470
8.5
16,769.0
0.385
2,454.0
0.1
15,542.0
0.4
68,606.8
0.7
471
9.5
19,391.0
0.445
2,622.0
0.1
18,080.0
0.4
86,686.8
0.8
472
10.5
22,183.0
0.509
2,792.0
0.1
20,787.0
0.5
107,473.8
0.9
472.5
11
26,973.0
0.619
4,790.0
0.1
12,289.0
0.3
119,762.8
0.8
2017.06.29.15-501. BM P.xls
Stage Storage (Perm Pool) Page 6 of 18 Printed 1/15/2018 9:29 AM

Project
Project No.
Date
15-501 BMP (West)
2735-0165
January 15, 2018
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Forebays
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
467
0
1,816.0
0.042
1,816.0
0.0
0.0
0.0
0.0
0.0
468
1
2,678.0
0.061
862.0
0.0
2,247.0
0.1
2,247.0
0.1
469
2
3,629.0
0.083
951.0
0.0
3,153.5
0.1
5,400.5
0.1
470
3
4,694.0
0.108
1,065.0
0.0
4,161.5
0.1
9,562.0
0.2
471
4
5,872.0
0.135
1,178.0
0.0
5,283.0
0.1
14,845.0
0.2
472
5
7,163.0
0.164
1,291.0
0.0
6,517.5
0.1
21,362.5
0.3
472.5
5.5
9,101.0
0.209
1,938.0
0.0
4,066.0
0.1
25,428.5
0.2
2017.06.29.15-501. BM P.xls
Stage Storage (Forebays) Page 7 of 18 Printed 1/15/2018 9:29 AM

Water Quality Basin Dewatering Time Calculations
Project 15-501 BMP (West)
Project No. 2735-0165
Date January 15, 2018
Water quality treatment volume
Total treatment volume
Maximum head of water above dewatering hole
Driving head
Orifice coefficient
Diameter of each hole
Number of holes
Cross sectional area of each hole =
Cross sectional area of each hole =
Cross sectional area of dewatering hole(s) _
Cross sectional area of dewatering hole(s) _
Dewatering time for water quality volume =
Dewatering time for total volume =
48,778
cubic feet
52,146
cubic feet
1.70
feet
0.56
feet
n an
3.50 inches
1
0.067 square feet
9.6 square inches
0.067 square feet
9.6 square inches
2.3 days
56.2 hours
2.5 days
60.1 hours
Notes:
Dewatering time formula: t (days) = V / (Cd*A*Sgrt (2*32.2*H)*86,400)
t = drawdown time
V = treatment volume
Cd = orifice coefficient
A = cross sectional area of orifice
H = driving head (1/3 max. head)

Water Quality Pond Summary Information
Project 15-501 BMP (West)
Project No. 2735-0165
Date January 15, 2018
Drainage area to pond 860,780 square feet=
Impervious area in drainage area 602,546 square feet =
Bottom of pond elevation
461.50
feet
Normal pool elevation
472.50
feet
Pond volume at normal pool
119,762
cubic feet
Forebay volume at normal pool
25,428
cubic feet
Forebay % of total volume
21.2%
Required volume for design rainfall 48,778 cubic feet
Required surface area for pond 26,260 square feet
19.76 acres
13.83 acres
Volume provided for storage of design rainfall = 52,146 cubic feet at elevation 474.2
Surface area provided at normal pool 26,972 square feet
Average Depth 4.44 feet
2017.06.29.15-501. BM P. xls
Summary Data Page 10 of 18 Printed 1/15/2018 9:29 AM

1S
Pre -Development
Subcat Reach Pon Link
2S
Post -De elopment
It7
A;
BMP #26

2017.06.29.BMP #26
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Pace 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
5.930 74 >75% Grass cover, Good, HSG C (2S)
13.830 98 Paved parking, HSG C (2S)
19.760 70 Woods, Good, HSG C (1 S)
39.520 80 TOTAL AREA

2017.06.29.BMP #26
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000
HSG A
0.000
HSG B
39.520
HSG C 1 S, 2S
0.000
HSG D
0.000
Other
39.520
TOTAL AREA

2017.06.29.BMP #26
Prepared by McKim & Creed
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC
Printed
1/15/2018
Page 4
Ground Covers (all nodes)
HSG -A
HSG -B
HSG -C
HSG -D
Other
Total
Ground
Subcatchment
(acres)
(acres)
(acres)
(acres)
(acres)
(acres)
Cover
Numbers
0.000
0.000
5.930
0.000
0.000
5.930
>75% Grass cover, Good
2S
0.000
0.000
13.830
0.000
0.000
13.830
Paved parking
2S
0.000
0.000
19.760
0.000
0.000
19.760
Woods, Good
is
0.000
0.000
39.520
0.000
0.000
39.520
TOTAL AREA

2O17.O6.29.BMP #26 Type 1124 -hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>0.00"
Flow Length=846' Tc=18.6 min CN=70 Runoff=0.01 cfs 0.003 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>0.32"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=9.18 cfs 0.534 of
Pond 3P: BMP #26 Peak Elev=473.10' Storage=17,428 cf Inflow=9.18 cfs 0.534 of
Outflow=0.22 cfs 0.136 of
Total Runoff Area= 39.520 ac Runoff Volume= 0.538 of Average Runoff Depth =0.16"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 TypeI124-hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1 S: Pre -Development
[73] Warning: Peak may fall outside time span
Runoff = 0.01 cfs @ 19.56 hrs, Volume= 0.003 af, Depth> 0.00"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 1 -Inch Rainfall=1.00"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
- - -
- - - -1
0.01 cfs
- - -
0.011
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
0.01
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
- - -
- - - -
I
- - - - -
- I - - L -
0.008
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
t
_f
- I
0.008
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
_ L
_ J 1
-
_ -1- _ L _
0.006
Woodland Kv= 5.0 fps
18.6 846 Total
❑Runoff
Subcatchment 1S: Pre -Development
Hydrograph
0.013
0.012
0.011 1
- - - - - I - - - _ - - - -
- - -
- - - -1
0.01 cfs
- - -
0.011
+ypell-24--hI + 1 1
1
1 -
0.01
J I . �
0.01
} .�`aT.4 I = f. 6 - - -1 - - 1-
�� i��
-
- - -1
- - -
0.009
0.009
,
- - - - - /�y -- - - - - -n- - - - - - -
R U rtoff-K1 e� 9. Wac-1--'--'---L--L
- - -
- - - -
I
- - - - -
- I - - L -
0.008
t 1 1- I + + � I I-
t
_f
- I
0.008
� /.
Rurrof�V B.flVQ3-af
0.007
0.007
Wlu-me.-
1 6 ^ rt,,1 _ J _ -I _ _ I_
Rnof ��110.006
_ L
_ J 1
-
_ -1- _ L _
0.006
0 1-0.005
FL
�1�>5��.L
���WCI�=-O`F9�- T - - -1- - 1-
-
1
- -1- - F
0.005
0.004
t 1 _c _ _ 1 _ _ 1 _ 1 _ 1 - - - - I-
♦Q�8.�1�IrrI�+
k-
0.004 0.004
0.003
1 =z
0.003
IN __I --I--1 - 1 - 1--I--I_
_-1--1--1--
0.002
4- A 1 I - -
0.002
t - - - -
0.001
0.001
- - - - - - - - - - - - - - - - - - -
- -
- - -
- - - - - -
0.000
0
5
6 7 8 9 10 11 12 13 14
15
16 17
18 19 20
Time (hours)
❑Runoff

2017.06.29.BMP #26 TypeI124-hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2S: Post -Development
Runoff = 9.18 cfs @ 12.07 hrs, Volume= 0.534 af, Depth> 0.32"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 1 -Inch Rainfall=1.00"
Area (ac)
CN
Description
5.930
74
>75% Grass cover, Good, HSG C
13.830
98
Paved parking, HSG C
19.760
91
Weighted Average
5.930
30.01 % Pervious Area
13.830
140
69.99% Impervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
0.7
140
0.2000
3.13
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
1.1
985
0.0230
14.31
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
14.1 1,225 Total
Subcatchment 2S: Post -Development
Hydrograph
L — — —I— — L — — —1- — -1 — —1— — L —
10
9-/ 1 1 1 Type II 24ohr
8 ,T rnciltalnfall 1.00"
Runoff Airea-19.760 lac
7
Runoff Vohume-0.11534raf
6
1 - noff Dopth;0.-$2„
LL 5 _ 1 _ -Fid-w 1Lenpth�1,22,T
4 1 Tc, -141 min
------- -------------
3 1 1 ON_191
2
I I I
1 I I I I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 9
Summary for Pond 3P: BMP #26
Inflow Area =
19.760 ac,
69.99% Impervious,
Inflow Depth > 0.32" for 1 -Inch event
Inflow =
9.18 cfs @
12.07 hrs, Volume=
0.534 of
Outflow =
0.22 cfs @
18.92 hrs, Volume=
0.136 af, Atten= 98%, Lag= 411.0 min
Primary =
0.22 cfs @
18.92 hrs, Volume=
0.136 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 473.10' @ 18.92 hrs Surf.Area= 30,521 sf Storage= 17,428 cf
Plug -Flow detention time= 255.1 min calculated for 0.135 of (25% of inflow)
Center -of -Mass det. time= 160.6 min ( 970.8 - 810.2 )
Volume Invert
Avail.Storage Storage Description
#1 472.50'
233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq -ft)
(cubic -feet) (cubic -feet)
472.50
26,972
0 0
473.00
30,316
14,322 14,322
474.00
32,321
31,319 45,641
475.00
34,358
33,340 78,980
476.00
36,454
35,406 114,386
477.00
38,610
37,532 151,918
478.00
40,898
39,754 191,672
479.00
43,204
42,051 233,723
Device Routing
Invert
Outlet Devices
#1 Primary
468.50'
36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50'
3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20'
36.0" W x 6.0" H Vert. Orifice/Grate C=0.600
#4 Device 1
476.47'
60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=0.22 cfs @ 18.92 hrs HW=473.10' (Free Discharge)
L1=Culvert (Passes 0.22 cfs of 56.34 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.22 cfs @ 3.25 fps)
3=Orifice/Grate ( Controls 0.00 cfs)
=Orifice/Grate ( Controls 0.00 cfs)

2017.06.29.BMP #26 TypeI124-hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 © 2015 HydroCAD Software Solutions LLC Paqe 10
Pond 3P: BMP #26
Hydrograph
r1l
■Inflow10— + — — —, — — — — s. s ors — — I ❑ Primary
Inflow, Area -19.760 ac
9— — — - ,— — r — — — i
Peak OeV-43.10
8
- Storage-�17,428'cf
- - ---- - - - - ----
H g
v i I I I I I I I I I
5 I-
0
4 TAT TI
3 T T T
2—
� I I I I I
1 I I I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2O17.O6.29.BMP #26 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 11
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>0.61"
Flow Length=846' Tc=18.6 min CN=70 Runoff=13.72 cfs 1.004 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>1.90"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=52.26 cfs 3.121 of
Pond 3P: BMP #26 Peak Elev=475.06' Storage=81,186 cf Inflow=52.26 cfs 3.121 of
Outflow=6.12 cfs 1.813 of
Total Runoff Area = 39.520 ac Runoff Volume = 4.125 of Average Runoff Depth = 1.25"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 12
Summary for Subcatchment 1 S: Pre -Development
Runoff = 13.72 cfs @ 12.14 hrs, Volume= 1.004 af, Depth> 0.61"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type 11 24 -hr 1 -Yr Rainfall=2.96"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
13
,2
_
11 1;Yr l aillifaf1�2.
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
- Runoff A ea=M7_60 ac
10
T 1
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
LL 7
- - - -
- - - - - - -
---- FlaW LehgW=846Y
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
-rt--1--1--
fi
Te -18.6 min
5f
4
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
2
Woodland Kv= 5.0 fps
18.6 846 Total
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 1S: Pre -Development
Hydrograph
1— L
L — — L
15 11
1
1 1
1 1 1 1 1
-
14 1
1 1
T 1
1 1 1
1 T T
1 13.72 crs I I I I
I - T 1 1 T Type 41-24 hr
13
,2
_
11 1;Yr l aillifaf1�2.
- - -1
1_ - ! - x
_
- Runoff A ea=M7_60 ac
10
T 1
1 T -1
1 1 1
- TRunoffi-Vo1ume-L1004raf
8
1 -
Tu0noff De,pAh�� 1 n
LL 7
- - - -
- - - - - - -
---- FlaW LehgW=846Y
6
-rt--1--1--
fi
Te -18.6 min
5f
4
4 1
I 1-
1 I - CN.70
-
- -
2
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 13
Summary for Subcatchment 2S: Post -Development
Runoff = 52.26 cfs @ 12.06 hrs, Volume= 3.121 af, Depth> 1.90"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type 11 24 -hr 1 -Yr Rainfall=2.96"
Area (ac)
CN
Description
5.930
74
>75% Grass cover, Good, HSG C
13.830
98
Paved parking, HSG C
19.760
91
Weighted Average
5.930
30.01 % Pervious Area
13.830
140
69.99% Impervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
0.7
140
0.2000
3.13
Shallow Concentrated Flow,
-t--1----fi-�--1
Short Grass Pasture Kv= 7.0 fps
1.1
985
0.0230
14.31
101.15 Pipe Channel,
_1 _
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
_ J _ _ I
V 30
n= 0.013
14.1 1,225 Total
Subcatchment 2S: Post -Development
Hydrograph
I Type 11-24011 r
-; - t;Yr kainfall 2.-9f 6"
Ri�no'ff A ea�19.760 rac
- Runoffs -Vo Irume-x.11121 of
L - -WO ,p h;A 0„
rt -T1bw Length=1,225+
1 - fico -l4A min-
-j - tN=91
inJ-tN=91
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff
55
50
L
45
1
-t--1----fi-�--1
40
35
_1 _
_ I_ _ L
_ J _ _ I
V 30
rt11fi�I
_o
LL 25
15-
10
I Type 11-24011 r
-; - t;Yr kainfall 2.-9f 6"
Ri�no'ff A ea�19.760 rac
- Runoffs -Vo Irume-x.11121 of
L - -WO ,p h;A 0„
rt -T1bw Length=1,225+
1 - fico -l4A min-
-j - tN=91
inJ-tN=91
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

2017.06.29.BMP #26 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 14
Summary for Pond 3P: BMP #26
Inflow Area = 19.760 ac, 69.99% Impervious, Inflow Depth > 1.90" for 1 -Yr event
Inflow =
52.26 cfs @ 12.06 hrs, Volume= 3.121 of
Outflow =
6.12 cfs @ 12.61 hrs, Volume= 1.813 af, Atten= 88%, Lag= 33.2 min
Primary =
6.12 cfs @ 12.61 hrs, Volume= 1.813 of
Routing by Stor-Ind
method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 475.06' @ 12.61 hrs Surf.Area= 34,492 sf Storage= 81,186 cf
Plug -Flow detention time= 181.1 min calculated for 1.813 of (58% of inflow)
Center -of -Mass det. time= 107.9 min ( 880.0 - 772.2 )
Volume Invert Avail.Storage Storage Description
#1 472.50' 233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store Cum.Store
(feet)
(sq -ft) (cubic -feet) (cubic -feet)
472.50
26,972 0 0
473.00
30,316 14,322 14,322
474.00
32,321 31,319 45,641
475.00
34,358 33,340 78,980
476.00
36,454 35,406 114,386
477.00
38,610 37,532 151,918
478.00
40,898 39,754 191,672
479.00
43,204 42,051 233,723
Device Routing
Invert Outlet Devices
#1 Primary
468.50' 36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50' 3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20' 36.0" W x 6.0" H Vert. Orifice/Grate C=0.600
#4 Device 1
476.47' 60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=6.12 cfs @ 12.61 hrs HW=475.06' (Free Discharge)
L1=Culvert (Passes 6.12 cfs of 76.59 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.50 cfs @ 7.49 fps)
3=Orifice/Grate (Orifice Controls 5.62 cfs @ 3.75 fps)
=Orifice/Grate ( Controls 0.00 cfs)

2017.06.29.BMP #26
Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed
Printed
1/15/2018
HydroCAD® 10.00-15
s/n 04927 © 2015 HydroCAD Software Solutions LLC
Paqe 15
Pond 3P: BMP #26
Hydrograph
t
I I
I I
I I
r t -1
I I I I I
1 r- t -1 1 1
■ Inflow
52.26cfs
I_
❑ Primary
55
- -
I
- - - -
I I
_ /� _ �I�+ �+
I nIlow-A�"flrea= l 9.760- ac
�
50
— —
— —i — —
— -POak
i
i—
tTeV-4-�5�-6'-
45
-
Storaoe-81,18611cf
40
1
1
L 1
_I
35
— —
T — —1 — — 1
1— — 7-
30-
30c
0
LL 25
— + —
+ — —1— —I—
— r — +
I — + — 1 I
20
— —
———
I I
F I
I I I I
�
15
L I
- L - I-
101 10 /
— T —
T —
T 6.12 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2O17.O6.29.BMP #26 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 16
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>0.94"
Flow Length=846' Tc=18.6 min CN=70 Runoff=22.26 cfs 1.545 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>2.44"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=66.29 cfs 4.012 of
Pond 3P: BMP #26 Peak Elev=475.68' Storage=102,970 cf Inflow=66.29 cfs 4.012 of
Outflow=8.57 cfs 2.678 of
Total Runoff Area = 39.520 ac Runoff Volume = 5.557 of Average Runoff Depth = 1.69"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 17
Summary for Subcatchment 1 S: Pre -Development
Runoff = 22.26 cfs @ 12.13 hrs, Volume= 1.545 af, Depth> 0.94"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 2 -Yr Rainfall=3.57"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
22
*
1 -r
-1
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
20
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
18
-+--1--1--+-+--1-
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
17
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
15
- ---1--1--
- --1-
Woodland Kv= 5.0 fps
18.6 846 Total
Subcatchment 1S: Pre -Development
Hydrograph
+ +JIL
+ = = + Type 41 24�hr
1 2;ir kailllifialf1-3- "
- Runoff Aihea-�t.7_60 br,
I I I I I I
_ = RLMffl:Voftj =-_ " h54� 51 of
TWpof� Dgpth4*4R
TI I T I�A'-17A
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
1 I
IL+I_
24
23
-+----1--4---4
22
*
1 -r
-1
1 -
21
20
-
1911�
18
-+--1--1--+-+--1-
17
16
_I _
- -
_ _ -
- -
_
15
- ---1--1--
- --1-
N 14
++I
13
- * - -1 -
-1- -
- -
-1-
`0 11
- 1 - - -
-I- -
- 1 --I-
10
--L--1--1--
-
--I-
9
+L+I
8
T
1
T
7
6
------I--
- --I-
5
++I
4
rt11�1-
+ +JIL
+ = = + Type 41 24�hr
1 2;ir kailllifialf1-3- "
- Runoff Aihea-�t.7_60 br,
I I I I I I
_ = RLMffl:Voftj =-_ " h54� 51 of
TWpof� Dgpth4*4R
TI I T I�A'-17A
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 18
Summary for Subcatchment 2S: Post -Development
Runoff = 66.29 cfs @ 12.06 hrs, Volume= 4.012 af, Depth> 2.44"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 2 -Yr Rainfall=3.57"
Area (ac)
CN
Description
5.930
74
>75% Grass cover, Good, HSG C
13.830
98
Paved parking, HSG C
19.760
91
Weighted Average
5.930
30.01 % Pervious Area
13.830
140
69.99% Impervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
65--
Woods: Light underbrush n= 0.400 P2= 3.56"
0.7
140
0.2000
3.13
Shallow Concentrated Flow,
T11T
Short Grass Pasture Kv= 7.0 fps
1.1
985
0.0230
14.31
101.15 Pipe Channel,
1 -k
50-1 1
1 1
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
-
45
1
1 1
n= 0.013
14.1 1,225 Total
Subcatchment 2S: Post -Development
Hydrograph
66.29 ds
---1i Type 1124ohr
- 2;a(K Oai6f,au��-I� - 7
T -Runoff Airea-t.760'ao
-i Runoffwo 1Gume-4.110112i of
J�noff Depth' .44"
-F46w Length-=�4,225'
—1 — — 1— Tc l4A min
- -1- - _ON -91
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff
T 1
-
1 t-
70-
706560
65--
60
T11T
55
4 1
1 -k
50-1 1
1 1
1 1
-
45
1
1 1
1
H
40
—+——I——I
35
_0
LL
30
— —
25
20-
0
15
1 5
10
66.29 ds
---1i Type 1124ohr
- 2;a(K Oai6f,au��-I� - 7
T -Runoff Airea-t.760'ao
-i Runoffwo 1Gume-4.110112i of
J�noff Depth' .44"
-F46w Length-=�4,225'
—1 — — 1— Tc l4A min
- -1- - _ON -91
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

2017.06.29.BMP #26 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 19
Summary for Pond 3P: BMP #26
Inflow Area =
19.760 ac, 69.99% Impervious, Inflow Depth > 2.44" for 2 -Yr event
Inflow =
66.29 cfs @ 12.06 hrs, Volume= 4.012 of
Outflow =
8.57 cfs @ 12.56 hrs, Volume= 2.678 af, Atten= 87%, Lag= 30.2 min
Primary =
8.57 cfs @ 12.56 hrs, Volume= 2.678 of
Routing by Stor-Ind
method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 475.68' @ 12.56 hrs Surf.Area= 35,792 sf Storage= 102,970 cf
Plug -Flow detention time= 173.1 min calculated for 2.669 of (67% of inflow)
Center -of -Mass det. time= 106.6 min ( 872.9 - 766.3 )
Volume Invert Avail.Storage Storage Description
#1 472.50' 233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store Cum.Store
(feet)
(sq -ft) (cubic -feet) (cubic -feet)
472.50
26,972 0 0
473.00
30,316 14,322 14,322
474.00
32,321 31,319 45,641
475.00
34,358 33,340 78,980
476.00
36,454 35,406 114,386
477.00
38,610 37,532 151,918
478.00
40,898 39,754 191,672
479.00
43,204 42,051 233,723
Device Routing
Invert Outlet Devices
#1 Primary
468.50' 36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50' 3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20' 36.0" W x 6.0" H Vert. Orifice/Grate C=0.600
#4 Device 1
476.47' 60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=8.57 cfs @ 12.56 hrs HW=475.68' (Free Discharge)
L1=Culvert (Passes 8.57 cfs of 81.14 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.56 cfs @ 8.39 fps)
3=Orifice/Grate (Orifice Controls 8.01 cfs @ 5.34 fps)
=Orifice/Grate ( Controls 0.00 cfs)

2017.06.29.BMP #26 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 20
Pond 3P: BMP #26
Hydrograph
I I I I I I I I I I
-
i
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
T-
-T ----I
---T
- -T -
------rt---I--I-
■Inflow
i❑
— � —
-4 — - —
— - — �
— 66.29 cfs —
- — - — � — + — –4— - — — — —
Primary
Y
70
Inflow Area -1 9.760 ac
65
�pl� �p�I�
60
=4'79.-08'
If %OF
55
- -}Oa—
� ICi
V
---4--1--1-
��7� I
50
_ 45
v 40
LL
30
I_
25
_ _ _
_ _ _I_
_I_ _
_
_ _ _ _
�
I
I I
I I
I
I I I
20
15
fi
rt 1
I
I
-I
10
/
J -J-
8.57 cfs
—
i
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2O17.O6.29.BMP #26 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>1.49"
Flow Length=846' Tc=18.6 min CN=70 Runoff=36.59 cfs 2.457 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>3.25"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=86.94 cfs 5.347 of
Pond 3P: BMP #26 Peak Elev=476.58' Storage=136,055 cf Inflow=86.94 cfs 5.347 of
Outflow=13.76 cfs 3.975 of
Total Runoff Area = 39.520 ac Runoff Volume = 7.804 of Average Runoff Depth = 2.37"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 22
Summary for Subcatchment 1 S: Pre -Development
Runoff = 36.59 cfs @ 12.12 hrs, Volume= 2.457 af, Depth> 1.49"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 5 -Yr Rainfall=4.47"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
- I
- -
-1-
t t I 5TYr 0aigf-QF-44�
30
28
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
fi
I T
1�1
T
rt11fiI1r
I - TRunoffiVOhj ne=G.14,7raf
N 24
``� 22
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
1
- ---
---1--Ia W=84W
1 1 1 1
16
14
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
-
- --1-
Q1 £ .
1 --1--1-- 1 --------
12
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
- ---
g
Woodland Kv= 5.0 fps
18.6 846 Total
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 1S: Pre -Development
Hydrograph
40
1 —
-_L
—
—
— — —
-I- - L - _L _L -I--�-
38
36
36.59 cfs — - — — — — — — —1-
1-36 Type al -24�hr
34-
32
t - -I -
- I
- -
-1-
t t I 5TYr 0aigf-QF-44�
30
28
-t--1--I--t----I-
t-MnoffAiheaw't9:760ac
26
rt11
T 1
fi
I T
1�1
T
rt11fiI1r
I - TRunoffiVOhj ne=G.14,7raf
N 24
``� 22
- T
I- - T
- T -
-1 - T 1 -Nnoff ��ptb�149��
LL 18
- --1----
1
- ---
---1--Ia W=84W
1 1 1 1
16
14
- --1-
-
- --1-
Q1 £ .
1 --1--1-- 1 --------
12
1
1 1
w'—jQ
1 1 �IY=1/ V
10
- ---
g
g
4
L------�1
L-L----I----
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 23
Summary for Subcatchment 2S: Post -Development
Runoff = 86.94 cfs @ 12.05 hrs, Volume= 5.347 af, Depth> 3.25"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 5 -Yr Rainfall=4.47"
Area (ac) CN Description
5.930 74 >75% Grass cover, Good, HSG C
13.830 98 Paved parking, HSG C
19.760 91 Weighted Average
5.930 30.01 % Pervious Area
13.830 69.99% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
12.3 100 0.0700 0.14 Sheet Flow,
0.7 140 0.2000 3.13
1.1 985 0.0230 14.31
14.1 1,225 Total
Woods: Light underbrush n= 0.400 P2= 3.56"
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 2S: Post -Development
Hydrograph
L
L
— L
95
1 1
I_ L
L
I L 1
1 1 L -1 I L
90
85
1 1
1 1
1_ L
1- —
L
— -1
I 86.94 cfs 1
— 1
1 1 L -1 I L
1 I LL Type 11 _24- h r
875
-
1 51 r ,yL�`ai�f�a�ll
1 1
1_
-1-
-
70
- 1 - -1 _
_ 1
1 -
-1 -1
y4._/
-R.tnoff Ai ea- 1 .7.760 to
65
60
_ 1--1--1
1 1
L-1--1
I L
1
Lp--1_ I-`,-1 I -A -'L-
--LRUMff1-�/D1Ume=5_i34/ Laf
R50
-1----I--L-�-
11-
�1�i�noffDepth� 514
LL 45
1 1
1 L
L
1- - 1
�#,22T
405——A1—
35
1
L
L
1
1 L TC1_♦ 4 min
n
30
25
- 1 - -1
1 -
- 1 -
- I _L
I- - L - -1�,,♦
WI
1'--I-LLI-
-11--L--
20
- 1 -
I-
1 -
-I
- - I
15
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 24
Summary for Pond 3P: BMP #26
[82] Warning: Early inflow requires earlier time span
Inflow Area = 19.760 ac, 69.99% Impervious, Inflow Depth > 3.25" for 5 -Yr event
Inflow = 86.94 cfs @ 12.05 hrs, Volume= 5.347 of
Outflow = 13.76 cfs @ 12.47 hrs, Volume= 3.975 af, Atten= 84%, Lag= 25.1 min
Primary = 13.76 cfs @ 12.47 hrs, Volume= 3.975 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 476.58' @ 12.47 hrs Surf.Area= 37,714 sf Storage= 136,055 cf
Plug -Flow detention time= 174.5 min calculated for 3.974 of (74% of inflow)
Center -of -Mass det. time= 113.8 min ( 873.9 - 760.1 )
Volume Invert
Avail.Storage Storage Description
#1 472.50'
233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq -ft)
(cubic -feet) (cubic -feet)
472.50
26,972
0 0
473.00
30,316
14,322 14,322
474.00
32,321
31,319 45,641
475.00
34,358
33,340 78,980
476.00
36,454
35,406 114,386
477.00
38,610
37,532 151,918
478.00
40,898
39,754 191,672
479.00
43,204
42,051 233,723
Device Routing
Invert
Outlet Devices
#1 Primary
468.50'
36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50'
3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20'
36.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
#4 Device 1
476.47'
60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=13.66 cfs @ 12.47 hrs HW=476.58' (Free Discharge)
L1=Culvert (Passes 13.66 cfs of 87.32 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.64 cfs @ 9.55 fps)
3=Orifice/Grate (Orifice Controls 10.54 cfs @ 7.03 fps)
4=Orifice/Grate (Weir Controls 2.48 cfs @ 1.10 fps)

2017.06.29.BMP #26
Type 1124-hr 5-Yr Rainfall=4.47"
Prepared by
McKim & Creed
Printed
1/15/2018
HydroCAD® 10.00-15
s/n 04927 © 2015 HydroCAD Software Solutions LLC
Paqe 25
Pond 3P: BMP #26
Hydrograph
———-1—-1———�—�—
————-1—-1——
■Inflow
95
,
+
86.94cfs1 �+ 1
❑ Primary
A,,�1c
0L ac-
85
80
,
— + —
— —I— —I—
—
— — —I— —I——A
� k ��=0-08 —
+
I
75
70
,
,
—+—�——I——I——�r
I-
ptoa�=J5
T
1 I
r
1C
65
,
+IIS
11r+1I
60
H 55
,
—7
—1—-1——r
—-1—-1——T-7—-1—-1—-1——
v50
/
T1IF11TT-11
_o 45
— T _
T —
—
_ T I— T _ T _ —
LL 40
,
35
— — —
— — — — — —
— —
— — — — -
30
i
25
20
15
,
13.76 cts
10
i
5
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2017.06.29.BMP #26 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 26
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>1.97"
Flow Length=846' Tc=18.6 min CN=70 Runoff=48.79 cfs 3.247 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>3.89"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=103.16 cfs 6.408 of
Pond 3P: BMP #26 Peak Elev=476.95' Storage=150,035 cf Inflow=103.16 cfs 6.408 of
Outflow=33.95 cfs 5.011 of
Total Runoff Area = 39.520 ac Runoff Volume = 9.656 of Average Runoff Depth = 2.93"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 27
Summary for Subcatchment 1 S: Pre -Development
Runoff = 48.79 cfs @ 12.12 hrs, Volume= 3.247 af, Depth> 1.97"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 10 -Yr Rainfall=5.18"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
+-
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
—T 1
1—
35
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
30
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
FL
Woodland Kv= 5.0 fps
18.6 846 Total
Subcatchment 1S: Pre -Development
Hydrograph
I
Type 11 -2411111h K
t110;Yr OainfaH:rZ}1;8"
R U n off Aeea� 19.760 'ac
T T—-1——I——F—
Runoff) Vollume-3.12471 of
Rynoff De;pth;'1.07"
RoW Lehgth-846'
1 I Tc -18.6 min
1�-- tN_;70
I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
_
L
50
45 1
+-
40
—T 1
1—
35
I
I
30
0
25
FL
+�I
20
1
1 1
1
T -
- --�
�-
15
10
1
I
Type 11 -2411111h K
t110;Yr OainfaH:rZ}1;8"
R U n off Aeea� 19.760 'ac
T T—-1——I——F—
Runoff) Vollume-3.12471 of
Rynoff De;pth;'1.07"
RoW Lehgth-846'
1 I Tc -18.6 min
1�-- tN_;70
I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 28
Summary for Subcatchment 2S: Post -Development
Runoff = 103.16 cfs @ 12.05 hrs, Volume= 6.408 af, Depth> 3.89"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 10 -Yr Rainfall=5.18"
Area (ac) CN Description
5.930 74 >75% Grass cover, Good, HSG C
13.830 98 Paved parking, HSG C
19.760 91 Weighted Average
5.930 30.01 % Pervious Area
13.830 69.99% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
12.3 100 0.0700 0.14 Sheet Flow,
0.7 140 0.2000 3.13
1.1 985 0.0230 14.31
14.1 1,225 Total
Woods: Light underbrush n= 0.400 P2= 3.56"
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
0-
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 2S: Post -Development
Hydrograph
115 1-
110
105
100
T
L
J
—1 1
1 L
1
i
103.16
cfs
L 1 1 1 Type It 24-ohr
90
-t--1--I--t--
--r-rt10-111�r air afl5. ; "-
85
80
— T
—
—
—
t
— T
T
—
—
__I 1-- R u no1f Aeea� 9.76�1ac-
1___1__1___
770
-
1 L
�
-
I I I I I I
- naf 11Zo7um .14081 of
60
-�------�-
--+Buoepth3.9"
M 50 -
1
-----�-T-
-�FCbw1ength:i1i225'-
I I I_
45
40
—
_ 1
————I——
_ J _
_ I _ _ I
—
_
— —-1—
_ 1 _ _I _ _ I �� —=1-4A- M_n-
35
30
J1I =—'a1
25
+
t
20
15
10
—I
0-
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2017.06.29.BMP #26 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 29
Summary for Pond 3P: BMP #26
[82] Warning: Early inflow requires earlier time span
Inflow Area =
19.760 ac,
69.99% Impervious,
Inflow Depth > 3.89" for 10 -Yr event
Inflow =
103.16 cfs @
12.05 hrs, Volume=
6.408 of
Outflow =
33.95 cfs @
12.28 hrs, Volume=
5.011 af, Atten= 67%, Lag= 13.8 min
Primary =
33.95 cfs @
12.28 hrs, Volume=
5.011 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 476.95' @ 12.28 hrs Surf.Area= 38,505 sf Storage= 150,035 cf
Plug -Flow detention time= 159.4 min calculated for 5.011 of (78% of inflow)
Center -of -Mass det. time= 103.2 min ( 859.6 - 756.5 )
Volume Invert
Avail.Storage Storage Description
#1 472.50'
233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq -ft)
(cubic -feet) (cubic -feet)
472.50
26,972
0 0
473.00
30,316
14,322 14,322
474.00
32,321
31,319 45,641
475.00
34,358
33,340 78,980
476.00
36,454
35,406 114,386
477.00
38,610
37,532 151,918
478.00
40,898
39,754 191,672
479.00
43,204
42,051 233,723
Device Routing
Invert
Outlet Devices
#1 Primary
468.50'
36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50'
3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20'
36.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
#4 Device 1
476.47'
60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=33.66 cfs @ 12.28 hrs HW=476.95' (Free Discharge)
L1=Culvert (Passes 33.66 cfs of 89.71 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.67 cfs @ 9.99 fps)
3=Orifice/Grate (Orifice Controls 11.41 cfs @ 7.61 fps)
4=Orifice/Grate (Weir Controls 21.58 cfs @ 2.26 fps)

2017.06.29.BMP #26 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 30
Pond 3P: BMP #26
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
Hydrograph
■ Inflow
115
110
i
i
- -
- L
- -
- 1
- - - -
- -j - -I-
- - - - 103.16 yrs - - - - - - - - - - - - - - - - -
- I- - -I - -I_ - I--�.7L�- I -n- - -
❑ Primary
105
/
4-
4
--II
I- - 4ipflow Area= 1 - 460 -ac
100
95
i
/
- -r
-
- rt
-
- ---1 - -
- -I - -
I - -I- - -1 - -1--0-
- - r - c C
- -I- - -I -Peak- �1eV--4 6 . —
90
i
—
—
— —
I 1
— — — n— �—_� — —
���e� V � JJ�
80
i
—
—
— — —1
— — 1— - — — _
75
i
— fi
— rt
— --I — —1—
— I- — rt — —1 — —1— — I— — t- — t — --I — —
70
/
T
I_ I_
_
_
_ _I _ _I_
_ _ _I_ _ _ _ _ _ _
60
i
_ I_ _
c 55
—
M 50
i
t
-f
-1
1 I 1 1 I F + -1
45
/
— T-
7
7 T T
40/
35
33.95 cfs 1
30
i
4
-
�
1 1-
25
25
i
— +
— -+
—
I — — I— -I — — I — — I— — i- — +
20
i
— T
— 7
— 7
1— — 1— -1— — I— — T — T I
15
i
-
-
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2017.06.29.BMP #26 Type 1124 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 31
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>2.66"
Flow Length=846' Tc=18.6 min CN=70 Runoff=66.00 cfs 4.378 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>4.76"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=124.73 cfs 7.834 of
Pond 3P: BMP #26 Peak Elev=477.34' Storage=165,133 cf Inflow=124.73 cfs 7.834 of
Outflow=65.96 cfs 6.405 of
Total Runoff Area= 39.520 ac Runoff Volume= 12.212 of Average Runoff Depth =3.71"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type // 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 32
Summary for Subcatchment 1 S: Pre -Development
Runoff = 66.00 cfs @ 12.11 hrs, Volume= 4.378 af, Depth> 2.66"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 25 -Yr Rainfall=6.13"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
65 x I
I I
I
I
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
55
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
50
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
45
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
40
Woodland Kv= 5.0 fps
18.6 846 Total
Subcatchment 1S: Pre -Development
Hydrograph
1 _ _1_ _ F
Type II 24ohr
26;Yraifalf13"
+—Rtmoff Aihea� 1.760 'ao
I I I I 1 I
I Runoff) Vollume=4.3781 of
JRA�1noff Depth l 10
IIGW L"tfh=846-
To-18.6 min
- - I- - I - CN=70
I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff
70
— — —1 —
— — — 4
— -4 —
—
65 x I
I I
I
I
60
55
50
45
40
'
—+———-1—-4—
35
I
I
I
_0
FL
30 1
1
1
25
20-
0
15
1 5
10
1 _ _1_ _ F
Type II 24ohr
26;Yraifalf13"
+—Rtmoff Aihea� 1.760 'ao
I I I I 1 I
I Runoff) Vollume=4.3781 of
JRA�1noff Depth l 10
IIGW L"tfh=846-
To-18.6 min
- - I- - I - CN=70
I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

2017.06.29.BMP #26 Type // 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 33
Summary for Subcatchment 2S: Post -Development
Runoff = 124.73 cfs @ 12.05 hrs, Volume= 7.834 af, Depth> 4.76"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 25 -Yr Rainfall=6.13"
Area (ac)
CN
Description
5.930
74
>75% Grass cover, Good, HSG C
13.830
98
Paved parking, HSG C
19.760
91
Weighted Average
5.930
I
30.01 % Pervious Area
13.830
140
69.99% Impervious Area
Tc
(min)
Length
(feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
100—
1
90 �
I
Woods: Light underbrush n= 0.400 P2= 3.56"
0.7
140
0.2000
3.13
Shallow Concentrated Flow,
o
rtt
LL 60-
Short Grass Pasture Kv= 7.0 fps
1.1
985
0.0230
14.31
101.15 Pipe Channel,
30
— - 1
20 I
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
14.1 1,225 Total
Subcatchment 2S: Post -Development
Hydrograph
I I I I I I
I ype It 24-ohr
-I _ 125IYr_Fj4ainfalls6.1;3"-
RU noff Af*ea=19.Tf Q'ac
- 4RunGff 11Volume=7. 4� af-
I - Runoff Depth-�4J&"-
rt Flow -L,
Tc=141 min
-------------------------------
❑ Runoff
130 -124.73
cf
120
110
— _I
100—
1
90 �
I
N 80
v 70
o
rtt
LL 60-
50
40
30
— - 1
20 I
I I I I I I
I ype It 24-ohr
-I _ 125IYr_Fj4ainfalls6.1;3"-
RU noff Af*ea=19.Tf Q'ac
- 4RunGff 11Volume=7. 4� af-
I - Runoff Depth-�4J&"-
rt Flow -L,
Tc=141 min
-------------------------------
❑ Runoff

2017.06.29.BMP #26 Type 1124 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 34
Summary for Pond 3P: BMP #26
[82] Warning: Early inflow requires earlier time span
Inflow Area =
19.760 ac,
69.99% Impervious,
Inflow Depth > 4.76" for 25 -Yr event
Inflow =
124.73 cfs @
12.05 hrs, Volume=
7.834 of
Outflow =
65.96 cfs @
12.21 hrs, Volume=
6.405 af, Atten= 47%, Lag= 9.3 min
Primary =
65.96 cfs @
12.21 hrs, Volume=
6.405 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 477.34' @ 12.21 hrs Surf.Area= 39,385 sf Storage= 165,133 cf
Plug -Flow detention time= 142.8 min calculated for 6.383 of (81% of inflow)
Center -of -Mass det. time= 92.4 min ( 845.1 - 752.7 )
Volume Invert
Avail.Storage Storage Description
#1 472.50'
233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq -ft)
(cubic -feet) (cubic -feet)
472.50
26,972
0 0
473.00
30,316
14,322 14,322
474.00
32,321
31,319 45,641
475.00
34,358
33,340 78,980
476.00
36,454
35,406 114,386
477.00
38,610
37,532 151,918
478.00
40,898
39,754 191,672
479.00
43,204
42,051 233,723
Device Routing
Invert
Outlet Devices
#1 Primary
468.50'
36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50'
3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20'
36.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
#4 Device 1
476.47'
60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=65.19 cfs @ 12.21 hrs HW=477.33' (Free Discharge)
L1=Culvert (Passes 65.19 cfs of 92.15 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.70 cfs @ 10.42 fps)
3=Orifice/Grate (Orifice Controls 12.26 cfs @ 8.17 fps)
4=Orifice/Grate (Weir Controls 52.24 cfs @ 3.03 fps)

2017.06.29.BMP #26 Type // 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 35
Pond 3P: BMP #26
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
T
7
� I
I + -
■ Inflow
I
1
1 1
1 1 124.73cfs I I
❑ Primary
130
I
I
I I
I n IoW rea= a(;
1t -76
120
T
7
7 1
1 - 7 I 7
pII- elakF-le= 4 Z. 4'
110
4--7�
-41
100
I
I
I I
I
i
90
— T
— 7
— — —1—
— -1 — —1— — 1— — T — T — 7 -
m 80
4
_ _ 1
_1 _ _ 1 _ _ 1_ _ 4- _ + _ -4_
v
70
I
I
I I
65.96 cfs
I I I I I I
c
/
LL 60
/
50
4-
-4
+
I_
40
_
_
_
_ _ _
I
I
I I I I
30
i
1
1
1
20
-
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2O17.O6.29.BMP #26 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 36
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=19.760 ac 0.00% Impervious Runoff Depth>3.85"
Flow Length=846' Tc=18.6 min CN=70 Runoff=95.30 cfs 6.336 of
Subcatchment 2S: Post -Development Runoff Area=19.760 ac 69.99% Impervious Runoff Depth>6.16"
Flow Length=1,225' Tc=14.1 min CN=91 Runoff=159.46 cfs 10.150 of
Pond 3P: BMP #26 Peak Elev=477.87' Storage=186,467 cf Inflow=159.46 cfs 10.150 of
Outflow=95.49 cfs 8.670 of
Total Runoff Area= 39.520 ac Runoff Volume= 16.486 of Average Runoff Depth =5.01"
65.01% Pervious= 25.690 ac 34.99% Impervious = 13.830 ac

2017.06.29.BMP #26 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 37
Summary for Subcatchment 1 S: Pre -Development
Runoff = 95.30 cfs @ 12.11 hrs, Volume= 6.336 af, Depth> 3.85"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 100 -Yr Rainfall=7.67"
Area (ac) CN Description
19.760 70 Woods, Good, HSG C
19.760 100.00% Pervious Area
Tc
Length
Slope
Velocity
Capacity Description
(min)
(feet)
(ft/ft)
(ft/sec)
(cfs)
12.3
100
0.0700
0.14
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
3.6
382
0.1280
1.79
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
0.3
92
0.0100
5.94
10.50 Pipe Channel,
18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38'
n= 0.013
2.4
272
0.1400
1.87
Shallow Concentrated Flow,
Woodland Kv= 5.0 fps
18.6 846 Total
Subcatchment 1S: Pre -Development
Hydrograph
105 — + — — — —I — — 1— — — 4 — —1 — — — — i — — —I — — ■Runoff
100 — rt — — — rt — —1 95.30 �5 — r — 1 — —1 — q —1 — —
95 T -1 1 T T T 1 L'F
I Type It ohr-
80 — 1 — I — — — 1 — I — — JO T7 Tl1a— 1 ll7.O
— —
— — — — — — — — — — — — — — —
75 1 - - -1 - - 1 - - - Rut nofUAeea=19.760-lac-
65 1 L - RunoffiVolum"- .3361 af
55 - + - L - Ru -1 o�.` a fh} 3.851
LL 45 t -i 1 r- 1 I 1- rt �+ 11
40 T -1 I F 1 _ I_T-_c=#_8rfrmin
_ _ _
35 — T A' I'^
30 1 — — -— — —-1——-1—-1-—OW-1�0-
25 —
20
15
10
5
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2017.06.29.BMP #26 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 38
Summary for Subcatchment 2S: Post -Development
Runoff = 159.46 cfs @ 12.05 hrs, Volume= 10.150 af, Depth> 6.16"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 100 -Yr Rainfall=7.67"
Area (ac) CN Description
5.930 74 >75% Grass cover, Good, HSG C
13.830 98 Paved parking, HSG C
19.760 91 Weighted Average
5.930 30.01 % Pervious Area
13.830 69.99% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
12.3 100 0.0700 0.14 Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
0.7 140 0.2000 3.13
1.1 985 0.0230 14.31
14.1 1,225 Total
101 0
5
Subcatchment 2S: Post -Development
Hydrograph
rt 7 T 159.46 cfs
t — — —I— — � — t — —
— — —— — —
4-
_j J
I
7
I I I
7 _ _I _ _ I_ _ T_ _ 7 _ _I _
r-rt--I--I- Type H24*hr
+100 Yr ;R-hfallr7.�7�'
-
Runoff Area:1-J 760 -lac
`R_ t�o�f�ToTlime�1-0�130; of
-I AunofT Depth>6.116
-Flaw Cength=_T 22_5'
- - -'I - - - Ta 4.1 Min-
1
rii n1 — —1— — r — -f M91-
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff

2017.06.29.BMP #26 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 39
Summary for Pond 3P: BMP #26
[82] Warning: Early inflow requires earlier time span
Inflow Area =
19.760 ac,
69.99% Impervious,
Inflow Depth > 6.16" for 100 -Yr event
Inflow =
159.46 cfs @
12.05 hrs, Volume=
10.150 of
Outflow =
95.49 cfs @
12.18 hrs, Volume=
8.670 af, Atten= 40%, Lag= 7.8 min
Primary =
95.49 cfs @
12.18 hrs, Volume=
8.670 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 477.87' @ 12.18 hrs Surf.Area= 40,606 sf Storage= 186,467 cf
Plug -Flow detention time= 126.5 min calculated for 8.668 of (85% of inflow)
Center -of -Mass det. time= 81.6 min ( 830.0 - 748.4 )
Volume Invert
Avail.Storage Storage Description
#1 472.50'
233,723 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq -ft)
(cubic -feet) (cubic -feet)
472.50
26,972
0 0
473.00
30,316
14,322 14,322
474.00
32,321
31,319 45,641
475.00
34,358
33,340 78,980
476.00
36,454
35,406 114,386
477.00
38,610
37,532 151,918
478.00
40,898
39,754 191,672
479.00
43,204
42,051 233,723
Device Routing
Invert
Outlet Devices
#1 Primary
468.50'
36.0" Round Culvert
L= 86.9' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 468.50'/ 468.00' S=0.0058'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
472.50'
3.5" Vert. Orifice/Grate C= 0.600
#3 Device 1
474.20'
36.0" W x 6.0" H Vert. Orifice/Grate C= 0.600
#4 Device 1
476.47'
60.0" x 60.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
Primary OutFlow Max=95.41 cfs @ 12.18 hrs HW=477.86' (Free Discharge)
t =Culvert (Inlet Controls 95.41 cfs @ 13.50 fps)
2=Orifice/Grate (Passes < 0.73 cfs potential flow)
3=Orifice/Grate (Passes < 13.33 cfs potential flow)
4=Orifice/Grate (Passes < 107.02 cfs potential flow)

2017.06.29.BMP #26 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 40
Pond 3P: BMP #26
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
Hydrograph
i I I I
■ Inflow
170
159.46 crs —7
❑ Primary
-
-
-
- linflowlArea-t9--76fl-ac
160
150
—T—�—-1
1
—�—-1—-1—- r— �
PeF-le�.4 7. T
140
1
l
130
120
110
100
95.49 ds - — — — — — — � — +
4
— 4
— — —1—
— 1— - -1 — — I — — 1— — f- — + — -
3 904
- 1 t-
o LL 80
-
� 1
1 1 I I t � -
70
i
—
—
— — —1
— — 1— — -1 — —1 — — 1— — — i 1
60
i
_ L
_ J
_1_
_ 1_ _ .1 _ _I_ _ 1— _ 1
50
_ L
_ J
_ J _ —1
_ _ 1— _ -1 _ _ _ _ 1— _
40
JJII
J
30
20
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

DATE: 01 /15/2018
DESIGNED BY: GCA
(PROJECT NAME: Briar PROJECT LOCATION: Chatham Co - SDuntv. NC 102735-0165 West PROJECT O: (CHECKED BY: BSS 1
Pond Name=
BMP #26
Riser Outer Width =
6.0 ft
Riser Resisting Force =
13,976 Ib
Riser Outer Length =
6.0 ft
Base Resisting Force =
21,675 Ib
Riser Inner Width =
5.0 ft
Total Resisting Force =
35,651 Ib
Riser Inner Length =
5.0 ft
Riser Height =
8.47 ft
Riser Buoyant Force =
19,027 Ib
Base Buoyant Force =
9,017 Ib
Concrete Base Length =
8.5 ft
Total Buoyant Force =
28,044 Ib
Concrete Base Width =
8.5 ft
Concrete Base Depth =
24 in
Factor of Safety
1.27 Design Acceptable

Wet Detention Pond #27
Design

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin Operation and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
❑ does ® does not incorporate a vegetated filter at the outlet.
This system (check one):
❑ does ® does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
— Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
— No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
— Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
— If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
— Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month and
within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a
Coastal County). Records of operation and maintenance should be kept in a known set
location and must be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element:
Potentialproblem:
How I will remediate theproblem:
The entire BMP
Trash/debris is present.
Remove the trash/debris.
The perimeter of the wet
Areas of bare soil and/or
Regrade the soil if necessary to
detention basin
erosive gullies have formed,
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.
Vegetation is too short or too
Maintain vegetation at a height of
long.
approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 1 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate the roblem:
The inlet device: pipe or
The pipe is clogged.
Unclog the pipe. Dispose of the
swale
sediment off-site.
The pipe is cracked or
Replace the pipe.
otherwise damaged.
Erosion is occurring in the
Regrade the swale if necessary to
swale.
smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
futureproblems with erosion.
The forebay
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design depth for
possible. Remove the sediment and
sediment storage.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred.
Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf
Best professional practices
Prune according to best professional
show that pruning is needed
practices
to maintain optimal plant
health.
Plants are dead, diseased or
Determine the source of the
dying.
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application to establish the
ground cover if a soil test indicates
it is necessary.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area
Sediment has accumulated to
Search for the source of the
a depth greater than the
sediment and remedy the problem if
original design sediment
possible. Remove the sediment and
storage depth.
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over
Consult a professional to remove
50% of the area.
and control the al al growth.
Cattails, phragmites or other
Remove the plants by wiping them
invasive plants cover 50% of
with pesticide (do not spray).
the basin surface.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 2 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The embankment
Shrubs have started to grow
Remove shrubs immediately.
on the embankment.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
A tree has started to grow on
Consult a dam safety specialist to
the embankment.
remove the tree.
An annual inspection by an
Make all needed repairs.
appropriate professional
shows that the embankment
needs re air. if applicable)
The outlet device
Clogging has occurred.
Clean out the outlet device. Dispose
of the sediment off-site.
The outlet device is dama _ ed
Repair or replace the outlet device.
The receiving water
Erosion or other signs of
Contact the local NC Division of
damage have occurred at the
Water Quality Regional Office, or
outlet.
the 401 Oversight Unit at 919-733-
1786.
The measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading and not readily penetrate into
accumulated sediments.
When the permanent pool depth reads _4.50 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 4.50 feet in the forebay, the sediment
shall be removed.
BASIN DIAGRAM
(fill in the blanks)
Sediment Removal E . 452.00 I Pe maizen\
------------■- -
- Volume
Bottom Elevatioi 451.00 -Ct Min.
Sediment
Storage
FOREBAY
Pool
Permanent Pool Elevation 456.50
Sediment Removal Elevation 452.00------ Volume
Bottom Elevation 451.00
MAIN POND
Form SW401-Wet Detention Basin O&M-Rev.4 Page 3 of 4
1 -ft n.
Sediment
Storage

Permit Number:
(to be provided by DWQ)
I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project name:Briar Chapel - SD West
BMP drainage area number:2 - Wet Detention Pond #27
Print name:Lee Bowman
Title: -Senior Project Manager
Address: 16 Windy Knoll Circle, Chapel Hill, NC 27516
Phone:[phone]
Signature: /�// D �"'e ��
Date: "((O� CI It //fJ
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
I, -C- a Notary Public for the State of
K�fin Crx I I)nc,._, County of tunorLm , do hereby certify that
GL-Q� � la CS4 personally appeared before me this Rq
day ofrte, and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal,
Iii ngr�
notary =
Pub�'O 2
d
I%rn co
SEAL
My commission expires (DI _:�3 / ;,, 0 ;Z ()
Form SW401-Wet Detention Basin O&M-Rev.4 Page 4 of 4

Permit No.
Red triangles at the upper right hand corner indicate design comments
Please complete the yellow shaded items.
AIMP—AA
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
Project name
Contact person
Phone number
Date
Drainage area number
Site Characteristics
Drainage area
Impervious area, post -development
% impervious
Design rainfall depth
Storage Volume: Non -SA Waters
Minimum volume required
Volume provided
Storage Volume: SA Waters
1.5" runoff volume
Pre -development 1 -yr, 24 -hr runoff
Post -development 1 -yr, 24 -hr runoff
Minimum volume required
Volume provided
Peak Flow Calculations
Is the pre/post control of the lyr 24hr storm peak flow required?
1 -yr, 24 -hr rainfall depth
Rational C, pre -development
Rational C, post -development
Rainfall intensity: 1 -yr, 24 -hr storm
Pre -development 1 -yr, 24 -hr peak flow
Post -development 1 -yr, 24 -hr peak flow
Pre/Post 1 -yr, 24 -hr peak flow control
Elevations
Temporary pool elevation
Permanent pool elevation
SHWT elevation (approx. at the perm. pool elevation)
Top of 1 Oft vegetated shelf elevation
Bottom of 1 Oft vegetated shelf elevation
Sediment cleanout, top elevation (bottom of pond)
Sediment cleanout, bottom elevation
Sediment storage provided
Is there additional volume stored above the state -required temp. pool?
Elevation of the top of the additional volume
919.233.8091
Briar Chapel - SD West
Gareth Avant, PE
9/30/2016, REVISED 01/15/2018
2 - Wet Pond #27
314,768 ft2
251,814 ft2
80.00 %
1.0 in
20,198 ft3
23,095 ft3
ft3
ft3
ft3
ft3
ft3
OK
(to be provided by DWQ)
O�O� W ATF9QG
li
y
o
OK, volume provided is equal to or in excess of volume required.
Y (Y or N)
3.0 in
0.40 (unitless)
0.82 (unitless)
0.13 in/hr OK
12.87 ft3/sec
47.65 ft3/sec
34.78 ft3/sec
457.50 fmsl
456.50 fmsl
fmsl
457.00 fmsl
456.00 fmsl Data not needed for calculation option 41, but OK if provided.
452.00 fmsl
451.00 fmsl Data not needed for calculation option 41, but OK if provided.
1nntr
N (Y or N)
fmsl
Form SW401-Wet Detention Basin-Rev.8-9/17/09 Parts I. & II. Design Summary, Page 1 of 2

Surface Areas
Area, temporary pool
Area REQUIRED, permanent pool
SADA ratio
Area PROVIDED, permanent pool, Apen-pool
Area, bottom of 1 Oft vegetated shelf, Abot shelf
Area, sediment cleanout, top elevation (bottom of pond), AW_,nd
Volumes
Volume, temporary pool
Volume, permanent pool, Vpenpool
Volume, forebay (sum of forebays if more than one forebay)
Forebay % of permanent pool volume
SADA Table Data
Design TSS removal
Coastal SADA Table Used?
Mountain/Piedmont SADA Table Used?
SADA ratio
Average depth (used in SADA table):
Calculation option 1 used? (See Figure 10-2b)
Volume, permanent pool, Vpenpool
Area provided, permanent pool, Aperm_pool
Average depth calculated
Average depth used in SA/DA, deV, (Round to nearest 0.5ft)
Calculation option 2 used? (See Figure 10-2b)
Area provided, permanent pool, Aperm_pool
Area, bottom of 1 Oft vegetated shelf, Abot shelf
Area, sediment cleanout, top elevation (bottom of pond), Abot_pond
"Depth" (distance b/w bottom of 1Oft shelf and top of sediment)
Average depth calculated
Average depth used in SA/DA, deV, (Round to nearest 0.5ft)
Drawdown Calculations
Drawdown through orifice?
Diameter of orifice (if circular)
Area of orifice (if -non -circular)
Coefficient of discharge (CD)
Driving head (Ho)
Drawdown through weir?
Weir type
Coefficient of discharge (CW)
Length of weir (L)
Driving head (H)
Pre -development 1 -yr, 24 -hr peak flow
Post -development 1 -yr, 24 -hr peak flow
Storage volume discharge rate (through discharge orifice or weir)
Storage volume drawdown time
Additional Information
Vegetated side slopes
Vegetated shelf slope
Vegetated shelf width
Length of flowpath to width ratio
Length to width ratio
Trash rack for overflow & orifice?
Freeboard provided
Vegetated filter provided?
Recorded drainage easement provided?
Capures all runoff at ultimate build -out?
Drain mechanism for maintenance or emergencies is:
Form SW401-Wet Detention Basin-Rev.8-9/17/09
19,218 ft2
13,850 ft2
4.40 (unitless)
15,132 ft2 OK
11,925 ft2
4,689 ft2
23,095 ft3 OK
49,121 ft3
9,392 ft3
19.1% % OK
90 %
N (Y or N)
Y (Y or N)
4.40 (unitless)
Y (Y or N)
49,121 ft3
15,132 ft2
3.22 ft OK
3.2 ft OK
N (Y or N)
15,132 ft2
11,925 ft2
4,689 ft2
4.00 ft
ft
ft
Y (Y or N)
2.50 in
int
0.60 (unitless)
0.43 ft
N (Y or N)
(unitless)
(unitless)
ft
ft
4.28 ft3/sec
2.42 ft3/sec
0.10 ft3/sec
2.50 days OK, draws down in 2-5 days.
owner
Permit No.
(to be provided by DWQ)
Parts I. & II. Design Summary, Page 2 of 2
3 :1
OK
10 :1
OK
10.0 ft
OK
3 :1
OK
1.5 :1
OK
Y
(Y or N)
OK
1.0 ft
OK
N
(Y or N)
OK
Y
(Y or N)
OK
Y
(Y or N)
OK
Gate valve with hand crank
and/or
owner
Permit No.
(to be provided by DWQ)
Parts I. & II. Design Summary, Page 2 of 2

WATER QUALITY POND #27 CALCULATIONS
Project Name
Briar Chapel - SD West Infrastructure - Phase 2
Project Number
02735-0165
Date
September 30, 2016
3rd revision
2nd revision
1 st revision
15 -Jan -18

Water Quality Pond Drainage Area Data
Project Briar Chapel - SD West Infrastructure - Phase 2
Project No. 02735-0165
Date January 15. 2018
Total site area 314,768 square feet = acres
Impervious areas
Drainage area to pond
Existing Proposed Change
[sf] [sf] [sf]
Other Drainage Area
Existing Proposed
[sf] [sf]
On-site buildings (BUA)
0
251,814
251,81
0
0
On-site streets
0
0
0
0
0
On-site alleys
0
0
0
0
0
On-site sidewalks
0
0
0
0
0
On-site future (open space)
0
0
0
0
0
Off-site future development
0
0
0
0
0
Contingenc 1
0
1 0 1
0 1
0
0
Total Impervious I
r
1 251,814 1
251,814 1
0
f"
Non -impervious areas
Drainage area to pond
Existing Proposed Change
[sf] [sf] [sf]
Other Drainage Area
Existing Proposed
[sf] [sf]
On-site grass/landscape
0
62,954
62,954
0
0
On-site woods
0
0
0
0
0
Other undeveloped
0
0
0
0
0
Total off-site non -impervious
0
0
0
0
0
Total non -impervious
0
62,954
62,954
0
0
Total Drainage Area 314,768 314,768 0 0
Percent Impervious 0.0 80.0 80.0 n/a
2018.01.11.Taylor.BMP.xls
Site Drainage Area Data Page 2 of 18 Printed 1/15/2018 8:59 AM

Water Quality Pond Surface Area Calculations
Project Briar Chapel - SD West Infrastructure - Phase 2
Project No. 02735-0165
Date January 15, 2018
Total on-site drainage area to pond 314,768 square feet
Total impervious area in drainage area 251,814 square feet
Average water depth of basin at normal pool 3.2 feet
Location of site Chatham County
Site region Piedmont
% Impervious cover 80.0 percent
If the site is in a coastal area, will a vegetative filter be used? n/a
Surface Area/Drainage Area Ratios:
For a site in the Piedmont (85%)
3.2 percent
For a site in the Piedmont (90%)
4.4 percent
For a site in a Coastal County w/ Vegetative Filter
6.5 percent
For a site in a Coastal County w/out Vegetative Filter
8.9 percent
Required surface area of pond:
For a site in the Piedmont (85%)
10,220.0 square feet
For a site in the Piedmont (90%)
13,730.0 square feet
For a site in a Coastal County w/ Vegetative Filter
20,400.0 square feet
For a site in a Coastal County w/out Vegetative Filter
28,080.0 square feet
Notes:
2018.01.11.Taylor. BMP.xls
Pond Surface Area Calcs Page 3 of 18 Printed 1/15/2018 8:59 AM

Water Quality Pond Stormwater Runoff Volume Calculations
Project
Project No.
Date
Drainage area
Impervious area
Rainfall depth
Percent Impervious
Briar Chapel - SD West Infrastructure - Ph
02735-0165
January 15, 2018
314,768
square feet
251,814
square feet
1.00
inches
R(v)=0.05+0.009*(Percent impervious)
Runoff coefficient - R(v)
percent
0.77 in/in
Runoff volume=(Design rainfall)*(R(v))*(Drainage area)
Runoff volume 20,197.6 cubic feet
Notes:
2018.01.11.Taylor. BMP.xls
Runoff Volume Calcs Page 4 of 18 Printed 1/15/2018 8:59 AM

Project
Project No.
Date
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Temporary Pool
Briar Chapel - SD West Infrastructure - Phase 2
02735-0165
January 15, 2018
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
456.5
0
15,132.0
0.347
15,132.0
0.3
0.0
0.0
0.0
0.0
457
0.5
17,885.0
0.411
17,885.0
0.1
8,254.3
0.2
8,254.3
0.2
457.8
1.3
19,218.0
0.441
19,218.0
0.0
14,841.2
0.3
23,095.5
0.5
458
1.5
19,517.0
0.448
19,517.0
0.0
3,873.5
0.1
26,969.0
0.4
459
2.5
21,189.0
0.486
21,189.0
0.0
20, 353.0
0.5
47, 322.0
0.6
460
3.5
22,902.0
0.526
22,902.0
0.0
22,045.5
0.5
69,367.5
1.0
461
4.5
24,728.0
0.568
24,728.0
0.0
23,815.0
0.5
93,182.5
1.1
462
5.5
26,610.0
0.611
26,610.0
0.0
25,669.0
0.6
118,851.5
1.1
2018.01.11.Taylor. BMP.xls
Stage Storage (Temp Pool) Page 5 of 18 Printed 1/15/2018 8:59 AM

Project
Project No.
Date
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Permanent Pool
Briar Chapel - SD West Infrastructure - Phase 2
02735-0165
January 15, 2018
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
451
0
5,070.0
0.116
5,070.0
0.1
0.0
0.0
0.0
0.0
452
1
6,290.0
0.144
1,220.0
0.0
5,680.0
0.1
5,680.0
0.1
453
2
7,616.0
0.175
1,326.0
0.0
6,953.0
0.2
12,633.0
0.3
454
3
9,066.0
0.208
1,450.0
0.0
8,341.0
0.2
20,974.0
0.4
455
4
10,618.0
0.244
1,552.0
0.0
9,842.0
0.2
30,816.0
0.4
456
5
12,284.0
0.282
1,666.0
0.0
11,451.0
0.3
42,267.0
0.5
456.5
5.5
15,132.0
0.347
2,848.0
0.1
6,854.0
0.2
49,121.0
0.4
2018.01.11.Taylor. BMP.xls
Stage Storage (Perm Pool) Page 6 of 18 Printed 1/15/2018 8:59 AM

Project
Project No.
Date
Water Quality Pond Volume Calculations
Stage -Storage Data for Pond - Forebays
Briar Chapel - SD West Infrastructure - Phase 2
02735-0165
January 15, 2018
Contour ID
Stage
Area
[sq. ft.]
Area
[acres]
Incremental
Area
[sq. ft.]
Incremental
Area
[acres]
Incremental
volume
[cu. ft]
Incremental
volume
[acre -ft]
Cumulative
volume
[cu. ft]
Cumulative
volume
[acre -ft]
451
0
469.0
0.011
469.0
0.0
0.0
0.0
0.0
0.0
452
1
840.0
0.019
371.0
0.0
654.5
0.0
654.5
0.0
453
2
1,254.0
0.029
414.0
0.0
1,047.0
0.0
1,701.5
0.0
454
3
1,731.0
0.040
477.0
0.0
1,492.5
0.0
3,194.0
0.1
455
4
2,258.0
0.052
527.0
0.0
1,994.5
0.0
5,188.5
0.1
456
5
2,842.0
0.065
584.0
0.0
2,550.0
0.1
7,738.5
0.1
456.5
5.5
3,775.0
0.087
933.0
0.0
1,654.3
0.0
9,392.8
0.1
2018.01.11.Taylor. BMP.xls
Stage Storage (Forebays) Page 7 of 18 Printed 1/15/2018 8:59 AM

Water Quality Basin Dewatering Time Calculations
Project Briar Chapel - SD West Infrastructure - Phase 2
Project No. 02735-0165
Date January 15, 2018
Water quality treatment volume
Total treatment volume
Maximum head of water above dewatering hole
Driving head
Orifice coefficient
Diameter of each hole
Number of holes
Cross sectional area of each hole =
Cross sectional area of each hole =
Cross sectional area of dewatering hole(s) _
Cross sectional area of dewatering hole(s) _
Dewatering time for water quality volume =
Dewatering time for total volume =
20,198
cubic feet
23,095
cubic feet
1.30
feet
0.43
feet
n an
2.50 inches
1
0.034 square feet
4.9 square inches
0.034 square feet
4.9 square inches
2.2 days
52.2 hours
2.5 days
59.7 hours
Notes:
Dewatering time formula: t (days) = V / (Cd*A*Sgrt (2*32.2*H)*86,400)
t = drawdown time
V = treatment volume
Cd = orifice coefficient
A = cross sectional area of orifice
H = driving head (1/3 max. head)

Water Quality Pond Summary Information
Project Briar Chapel - SD West Infrastructur(
Project No. 02735-0165
Date January 15, 2018
Drainage area to pond
314,768
square feet= 7.23 acres
Impervious area in drainage area
251,814
square feet = 5.78 acres
Bottom of pond elevation
451.00
feet
Normal pool elevation
456.50
feet
Pond volume at normal pool
49,121
cubic feet
Forebay volume at normal pool
9,392
cubic feet
Forbay % of total volume
19.1%
Required volume for design rainfall 20,198 cubic feet
Required surface area for pond 13,730 square feet
Volume provided for storage of design rainfall = 23,095 cubic feet at elevation 457.8
Surface area provided at normal pool 15,132 square feet
Average Depth 3.25 feet
2018.01.11.Taylor.BMP.xls
Summary Data Page 10 of 18 Printed 1/15/2018 8:59 AM

Pre -Development Post- Development
3P
BMP #27
Subcat Reach Pon Link

2018.01.11.BMP #27
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Pace 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
1.450 74 >75% Grass cover, Good, HSG C (2S)
5.780 98 Paved parking, HSG C (2S)
7.230 70 Woods, Good, HSG C (1 S)
14.460 82 TOTAL AREA

2018.01.11.BMP #27
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 3
Soil Listing (all nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000
HSG A
0.000
HSG B
14.460
HSG C 1 S, 2S
0.000
HSG D
0.000
Other
14.460
TOTAL AREA

2018.01.11.BMP #27
Prepared by McKim & Creed
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC
Printed
1/15/2018
Page 4
Ground Covers (all nodes)
HSG -A
HSG -B
HSG -C
HSG -D
Other
Total
Ground
Subcatchment
(acres)
(acres)
(acres)
(acres)
(acres)
(acres)
Cover
Numbers
0.000
0.000
1.450
0.000
0.000
1.450
>75% Grass cover, Good
2S
0.000
0.000
5.780
0.000
0.000
5.780
Paved parking
2S
0.000
0.000
7.230
0.000
0.000
7.230
Woods, Good
is
0.000
0.000
14.460
0.000
0.000
14.460
TOTAL AREA

2018.01.11.BMP #27 Type 1124 -hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>0.00"
Flow Length=962' Tc=23.8 min CN=70 Runoff=0.00 cfs 0.001 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>0.41"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=4.97 cfs 0.248 of
Pond 3P: BMP #27 Peak Elev=456.99' Storage=8,054 cf Inflow=4.97 cfs 0.248 of
Primary=0.10 cfs 0.066 of Secondary=0.00 cfs 0.000 of Outflow=0.10 cfs 0.066 of
Total Runoff Area = 14.460 ac Runoff Volume = 0.249 of Average Runoff Depth = 0.21"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 TypeI124-hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1 S: Pre -Development
[73] Warning: Peak may fall outside time span
Runoff = 0.00 cfs @ 19.66 hrs, Volume= 0.001 af, Depth> 0.00"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 1 -Inch Rainfall=1.00"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
0.004
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
I_
Woodland Kv= 5.0 fqs
23.8 962 Total
■Runoff
Subcatchment 1S: Pre -Development
Hydrograph
- t - _ - -1 - - 1- - t- - I-
- t
- fi - -1
- -I-
I -0.005
0.005
-T -T --1--1--T- 1 -1--T-T--1--1--T-
0.004
0.00 cfs
0.004
0.004
Tp�ealaIII
I_
0.004-t"'-'�I'1=`�t�-------T-�--I
0.004
-------t-fi
--�-
0.003
0.003
pp /+�4y e�{�
RUnoff- ew-Mew�-
--7-
0.003
----T
l 1 1 11
I� 1
0.003
p A /
RUft6 I Y-W4ume O.D�I�� 1 1
I
I
0.003
-
w 0.003
pp
� �. ��r� 1
1
J I
I
0.002
n��
q `OT T'i tt�I�
_0 0.002Flbw1__en--th�-9�Q'-
LL 0.002
- --11--11--T
--11--; -
0.002
-------------
T*423.8 fin
------
0.002
-1_-
0.001CIS--70-
0.001
�-IIIA
0.001
TT11T -11
117
0.001
T -----T - -
0.001
0.000
-
- -
- - - - I- -
0.000
0
5
6 7 8 9 10 11 12 13 14
15
16 17
18 19 20
Time (hours)
■Runoff

2018.01.11.BMP #27 TypeI124-hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2S: Post -Development
Runoff = 4.97 cfs @ 12.02 hrs, Volume= 0.248 af, Depth> 0.41"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 1 -Inch Rainfall=1.00"
Area (ac) CN Description
1.450 74 >75% Grass cover, Good, HSG C
5.780 98 Paved parking, HSG C
7.230 93 Weighted Average
1.450 20.06% Pervious Area
5.780 79.94% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
8.1 115 0.0950 0.24 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473 0.0230 14.31 101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
9.8 1,588 Total
Subcatchment 2S: Post -Development
Hydrograph
❑ Runoff
4.97 cfs
5 Type II 24ohr
L _ _)-Inch Rainfall -1.d0"
4 Runoff Area -7.230 ac
Runoff i Volume=0.248 of
3 Runoff Depth>0.41 "
LL Flow Length_ 1,588'
2 Tic=9�8 min
ON_'93
1 I I I
0,
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.BMP #27 Type 1124 -hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 9
Summary for Pond 3P: BMP #27
Inflow Area = 7.230 ac, 79.94% Impervious, Inflow Depth > 0.41" for 1 -Inch event
Inflow = 4.97 cfs @ 12.02 hrs, Volume= 0.248 of
Outflow = 0.10 cfs @ 17.95 hrs, Volume= 0.066 af, Atten= 98%, Lag= 356.1 min
Primary = 0.10 cfs @ 17.95 hrs, Volume= 0.066 of
Secondary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 456.99' @ 17.95 hrs Surf.Area= 17,823 sf Storage= 8,054 cf
Plug -Flow detention time= 260.5 min calculated for 0.066 of (26% of inflow)
Center -of -Mass det. time= 168.6 min ( 964.9 - 796.3 )
Volume Invert Avail.Storage Storage Description
#1 456.50' 118,838 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq -ft) (cubic -feet) (cubic -feet)
456.50 15,132 0 0
457.00 17,885 8,254 8,254
458.00 19,517 18,701 26,955
459.00 21,189 20,353 47,308
460.00 22,902 22,046 69,354
461.00 24,728 23,815 93,169
462.00 26,610 25,669 118,838
Device Routing Invert Outlet Devices
#1 Primary 451.00' 24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2 Device 1 456.50' 2.5" Vert. Orifice/Grate C= 0.600
#3 Device 1 457.80' 24.0" W x 5.0" H Vert. Orifice/Grate C=0.600
#4 Device 1 459.54' 42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5 Secondary 460.50' 10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=0.10 cfs @ 17.95 hrs HW=456.99' (Free Discharge)
t-1=Culvert (Passes 0.10 cfs of 33.79 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.10 cfs @ 2.99 fps)
3=Orifice/Grate ( Controls 0.00 cfs)
=Orifice/Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
t-5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27 Type 1124 -hr 1 -Inch Rainfall=1.00"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 10
N
V
O
LL
Pond 3P: BMP #27
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Outflow
❑ Primary
❑ Secondary

2018.01.11.BMP #27 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 11
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>0.61"
Flow Length=962' Tc=23.8 min CN=70 Runoff=4.28 cfs 0.366 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>2.07"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=23.42 cfs 1.250 of
Pond 3P: BMP #27 Peak Elev=458.32' Storage=33,369 cf Inflow=23.42 cfs 1.250 of
Primary=2.42 cfs 0.680 of Secondary=0.00 cfs 0.000 of Outflow=2.42 cfs 0.680 of
Total Runoff Area = 14.460 ac Runoff Volume = 1.616 of Average Runoff Depth = 1.34"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 12
Summary for Subcatchment 1 S: Pre -Development
Runoff = 4.28 cfs @ 12.20 hrs, Volume= 0.366 af, Depth> 0.61"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type 11 24 -hr 1 -Yr Rainfall=2.96"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
Woodland Kv= 5.0 fqs
23.8 962 Total
Subcatchment 1S: Pre -Development
Hydrograph
❑ Runoff
N
3
0
LL 2
I I
----�TypeH24-hr
1 -Yr Rainfall 2.96"
Runoff Area -7.230 ac
I Runoff i Volume -0.366 of
Runoff De;pth;>0.O1"
- TIovVr- L-ehgth=96T
Tc -23.8 min
CN -70
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.13MP #27 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 13
Summary for Subcatchment 2S: Post -Development
Runoff = 23.42 cfs @ 12.01 hrs, Volume= 1.250 af, Depth> 2.07"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type 11 24 -hr 1 -Yr Rainfall=2.96"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
— — 1 23.42 cfs —
-t--1--1--fi
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
—
— — 1 23.42 cfs —
-t--1--1--fi
— — — — — — — — — — — —
Type 112$thr
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
__I_ u
-,Yr-.66
1
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
I
n= 0.013
9.8 1,588 Total
■Runoff
Subcatchment 2S: Post -Development
Hydrograph
26
t1I---rrt---
-Ir
24
23
— — —1
-t--1--I--fi
— — I — —
—
— — 1 23.42 cfs —
-t--1--1--fi
— — — — — — — — — — — —
Type 112$thr
22
20 1
-4- _I__I__
__I_
---k
__I_ u
-,Yr-.66
1
I -k--4
I
19
18
I
I I
I
rtI
I
C
- I 1pdfA�aI0I
17
1- - T
- --4
6Itff1V0l1ae-�2c��16
- -I- WO
v 14
- - -
L
- -'- -
-
- -' -
- -1 ref Dgpth�2-7„
n
13
12
11
-+--I--1--4--�--I-
-7
-
-o}
-1-R YY Len�l_II_�195
19
T 1
_ 1--I--I--L
T
_
1 T A @ F-
_I_ _I_ _L- 978IIlki
8
7
+
-T --1--1--T
_
+
1 1 � -1 Q
6
1
1 7--1--1--7--T-I�
- -
5
1 1
1 L
-
I- - 1
1 1 L -1 1 L
4
3
f- + - -1
T - -
- - 1- -
-
- +
T
- -1 +
- - -'- - - --i - -I- - -
1
0
5
6 7
8 9
10
11 12 13
Time (hours)
14 15 16 17 18 19 20
■Runoff

2018.01.11.BMP #27 Type 1124 -hr 1 -Yr Rainfall=2.96"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 14
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area = 7.230 ac, 79.94% Impervious, Inflow Depth > 2.07" for 1 -Yr event
Inflow =
23.42 cfs @
12.01 hrs,
Volume=
1.250 of
Outflow =
2.42 cfs @
12.50 hrs,
Volume=
0.680 af, Atten= 90%, Lag= 29.7 min
Primary =
2.42 cfs @
12.50 hrs,
Volume=
0.680 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 458.32' @ 12.50 hrs Surf.Area= 20,059 sf Storage= 33,369 cf
Plug -Flow detention time= 191.6 min calculated for 0.680 of (54% of inflow)
Center -of -Mass det. time= 114.7 min ( 875.2 - 760.4 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=2.42 cfs @ 12.50 hrs HW=458.32' (Free Discharge)
L1=Culvert (Passes 2.42 cfs of 38.04 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.22 cfs @ 6.31 fps)
3=Orifice/Grate (Orifice Controls 2.21 cfs @ 2.65 fps)
=Orifice/Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27
Type 1124 -hr 1 -Yr
Rainfall=2.96"
Prepared by McKim & Creed
Printed 1/15/2018
HydroCAD® 10.00-15
s/n 04927 © 2015 HydroCAD Software Solutions LLC
Paqe 15
Pond 3P: BMP #27
Hydrograph
I I—t—t—t—t--t—
/
-�-�-!
-L-�-
L------�-�-
■Inflow
/-
cfs
-�I-ow A eY i
Primary
26
24
/
-
- -�
I I .-27O
-r -T T
' v�4403F'�eak9
■ Secondary ary
22
/ / / /
/ /
_
_
_ _
_ StOt =n.3W -d
1
20
18
/// /I
1
1
1 1 1 1 1 1
1 1 1 1 1 1
/
/I
+-+-+-+--F
_ 16-/
/
14-/
12
/ /I
_c
E:/
10
/
/ /
-
t-
t- t -
1
I- I t- t-
8
6
/ /
2.42 cfs
4
/
2.42 cfs
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.BMP #27 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 16
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>0.94"
Flow Length=962' Tc=23.8 min CN=70 Runoff=6.98 cfs 0.564 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>2.63"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=29.22 cfs 1.582 of
Pond 3P: BMP #27 Peak Elev=458.71' Storage=41,271 cf Inflow=29.22 cfs 1.582 of
Primary=3.59 cfs 1.001 of Secondary=0.00 cfs 0.000 of Outflow=3.59 cfs 1.001 of
Total Runoff Area = 14.460 ac Runoff Volume = 2.146 of Average Runoff Depth = 1.78"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 17
Summary for Subcatchment 1 S: Pre -Development
Runoff = 6.98 cfs @ 12.19 hrs, Volume= 0.564 af, Depth> 0.94"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 2 -Yr Rainfall=3.57"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
(min) (feet)
Slope
(ft/ft)
Velocity
(ft/sec)
Capacity Description
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
o
Woodland Kv= 5.0 fqs
23.8 962 Total
Subcatchment 1S: Pre -Development
Hydrograph
f —1 — — 1—
I Type II 24ohr
27Yr Rair�faltr3�7'}
Runoff Areal=7.230'ac
T — -I — —1 7 — T I
1 Runoff) Volume -0.5641 of
L Runoff De;pt1y;10-94"
- ! Flow Lehgth-962'
Tc -23.8 min
- CN X
10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff
6
1
5
4
o
I
I I
LL
1
3
I I
1 -
Subcatchment 1S: Pre -Development
Hydrograph
f —1 — — 1—
I Type II 24ohr
27Yr Rair�faltr3�7'}
Runoff Areal=7.230'ac
T — -I — —1 7 — T I
1 Runoff) Volume -0.5641 of
L Runoff De;pt1y;10-94"
- ! Flow Lehgth-962'
Tc -23.8 min
- CN X
10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff

2018.01.11.13MP #27 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 18
Summary for Subcatchment 2S: Post -Development
Runoff = 29.22 cfs @ 12.01 hrs, Volume= 1.582 af, Depth> 2.63"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 2 -Yr Rainfall=3.57"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
26
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
+1fi�I
n= 0.013
9.8 1,588 Total
Subcatchment 2S: Post -Development
Hydrograph
32-
2
— —
—
30--/
30
C
26
+1fi�I
24-
4
22:
22
20
18
g 16
12
— 1 — _I
L
_ _I
10
8
6
Type ll24oli r
t ; 2 �Yr ainfallr3. 7"
- - Runoff Area -T-230 be
Ru-noff,VoGume=1.15821 of
ROnoff Dgptb;>2�3„
+-16w Len ft=1l 588'
_ 1 c=93 min
-93
—
—1— — -
-IF
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.BMP #27 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 19
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area = 7.230 ac, 79.94% Impervious, Inflow Depth > 2.63" for 2 -Yr event
Inflow =
29.22 cfs @
12.01 hrs,
Volume=
1.582 of
Outflow =
3.59 cfs @
12.41 hrs,
Volume=
1.001 af, Atten= 88%, Lag= 24.4 min
Primary =
3.59 cfs @
12.41 hrs,
Volume=
1.001 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 458.71' @ 12.41 hrs Surf.Area= 20,707 sf Storage= 41,271 cf
Plug -Flow detention time= 177.4 min calculated for 1.001 of (63% of inflow)
Center -of -Mass det. time= 106.9 min ( 862.4 - 755.5 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=3.59 cfs @ 12.41 hrs HW=458.71' (Free Discharge)
L1=Culvert (Passes 3.59 cfs of 39.19 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.24 cfs @ 6.99 fps)
3=Orifice/Grate (Orifice Controls 3.35 cfs @ 4.02 fps)
=Orifice/Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27 Type 1124 -hr 2 -Yr Rainfall=3.57"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 20
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary
Pond 3P: BMP #27
Hydrograph
/
L L 29.22 cfs
nIQw-Ara�ac
e
32
30
,
/
L L L L L L
v
e& -U I .
28
26
,'
'
/
,
_ _ _ _ 11
— — — — — — — —
- - ! atotaglO=41,271-d
24
22
20
y
v 18
,
/
', I
'
_ _ _ _ _ _ _ _ _ _ _ _
I I I I I I I I I I
I I I I
g 16
o
LL 14
/
/
i
' /I
,I
1 1 1 1 1 1 1 1
1
12
10
i
/I
/ /I
1 1 1 1 1 1 1
8
g
/
/ ,1
1— — T— — T— — r 3.59 ds —
3.59 cfs
4
----------------
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary

2018.01.11.BMP #27 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>1.49"
Flow Length=962' Tc=23.8 min CN=70 Runoff=11.50 cfs 0.897 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>3.45"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=37.73 cfs 2.076 of
Pond 3P: BMP #27 Peak Elev=459.30' Storage=53,808 cf Inflow=37.73 cfs 2.076 of
Primary=4.83 cfs 1.481 of Secondary=0.00 cfs 0.000 of Outflow=4.83 cfs 1.481 of
Total Runoff Area = 14.460 ac Runoff Volume = 2.973 of Average Runoff Depth = 2.47"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 22
Summary for Subcatchment 1 S: Pre -Development
Runoff = 11.50 cfs @ 12.18 hrs, Volume= 0.897 af, Depth> 1.49"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 5 -Yr Rainfall=4.47"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
4 1
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
9
I I
I I
Woodland Kv= 5.0 fqs
23.8 962 Total
Subcatchment 1S: Pre -Development
Hydrograph
1I T- 11-24.1i r
5;Yr k infaH 4..47"
Runoff Area -7.230 ac
4- 1 I � A I I -I Runoff) Volume -0.897 of
1 1 Rdnoff Dgpth;1A.49"
Fl(x ► Lehgth-962'
1 Tc -23.8 min
— 1— — —
CN -=710
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff
SII—
�I
12-_[
-----------
11
I I
I I
I
4 1
- —
10
I
1 1
9
I I
I I
I I
4 1
-4 _
8-
g
7-
4
6
LL
5
4
3
2-
1
1I T- 11-24.1i r
5;Yr k infaH 4..47"
Runoff Area -7.230 ac
4- 1 I � A I I -I Runoff) Volume -0.897 of
1 1 Rdnoff Dgpth;1A.49"
Fl(x ► Lehgth-962'
1 Tc -23.8 min
— 1— — —
CN -=710
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

2018.01.11.13MP #27 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 23
Summary for Subcatchment 2S: Post -Development
Runoff = 37.73 cfs @ 12.01 hrs, Volume= 2.076 af, Depth> 3.45"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 5 -Yr Rainfall=4.47"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
9.8 1,588 Total
Subcatchment 2S: Post -Development
Hydrograph
40 — —
37.73 cfs +
38 ———-1--I---- --I- - - Typell-24ohr
36
34
32 5 iYr kaI6f07,�
30 _ ! _ _I _ _ _ _ ! _ ! _ _ _ _ ! - -Ru nWf Areal= -7,23 0 6c
28 _ 1 _ _I _ _ I— _ L _ J _ _ I _ _ 1 p_ _I _ _ I— `,_ L _ J _ —I _ _ L
26 + 1 I t- + I --AU ffi-VOlume-2.107-c -af
N 24 + + + I - + + noff D�p_th�_:45R
22 — + — —I — — I— — — + — — I — + — —I _1111M ,�■r {, {
`0 18 T 1 I t-+ I — + 1 Tlil! L� th=e ,5w
T I I T + I — T 1 1 T '- —I
16 + T + + + TI C_7L8 min
14 —
10
8 - — — — — —
6
A
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.BMP #27 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 24
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area = 7.230 ac, 79.94% Impervious, Inflow Depth > 3.45" for 5 -Yr event
Inflow =
37.73 cfs @
12.01 hrs,
Volume=
2.076 of
Outflow =
4.83 cfs @
12.39 hrs,
Volume=
1.481 af, Atten= 87%, Lag= 23.1 min
Primary =
4.83 cfs @
12.39 hrs,
Volume=
1.481 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 459.30' @ 12.39 hrs Surf.Area= 21,708 sf Storage= 53,808 cf
Plug -Flow detention time= 173.4 min calculated for 1.476 of (71% of inflow)
Center -of -Mass det. time= 110.3 min ( 860.6 - 750.3 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=4.83 cfs @ 12.39 hrs HW=459.30' (Free Discharge)
L1=Culvert (Passes 4.83 cfs of 40.88 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.27 cfs @ 7.91 fps)
3=Orifice/Grate (Orifice Controls 4.56 cfs @ 5.47 fps)
=Orifice/Grate ( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27 Type 1124 -hr 5 -Yr Rainfall=4.47"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 25
0
0
Pond 3P: BMP #27
Hydrograph
low re -La= ��o ad
St0ta"=53-. 08 -&
fi-fi-rt-rt-rt-rt-rt-
I
I
I
37.73 cf
L L
L L
L L L
L
L L-
— T
------------
— T —
T
— T
— T —
T-
�L����
1
1
1
1
— +
_ +
_t__t
-----!
-!
-!
-!
-----L
-L
-L
--
—
— —
}
4.83 cfs
low re -La= ��o ad
St0ta"=53-. 08 -&
fi-fi-rt-rt-rt-rt-rt-
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary
+
+
+
+
+
— T
------------
— T —
T
— T
— T —
T-
�L����
— +
_ +
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary

2018.01.11.BMP #27 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 26
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>1.97"
Flow Length=962' Tc=23.8 min CN=70 Runoff=15.37 cfs 1.186 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>4.09"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=44.40 cfs 2.466 of
Pond 3P: BMP #27 Peak Elev=459.70' Storage=62,474 cf Inflow=44.40 cfs 2.466 of
Primary=8.33 cfs 1.861 of Secondary=0.00 cfs 0.000 of Outflow=8.33 cfs 1.861 of
Total Runoff Area = 14.460 ac Runoff Volume = 3.652 of Average Runoff Depth = 3.03"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 27
Summary for Subcatchment 1 S: Pre -Development
Runoff = 15.37 cfs @ 12.18 hrs, Volume= 1.186 af, Depth> 1.97"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 10 -Yr Rainfall=5.18"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
L
_ J _
_ 1 15.37 cfs
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
14
Woodland Kv= 5.0 fqs
23.8 962 Total
Subcatchment 1S: Pre -Development
Hydrograph
-1 _ _I_ _ L
- - I i Type 1124ohr
O;Y N
r�if�51$„
Runoff Areal=7.230'ac
T T—-1—-1 _F—
tFRLMffiA/flIume=f.lf8$raf
+ - lRujnoff DgpthO1 .0-
FIaW Le#tg#h=962'
---�-- 1I T_c=23.8min_0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
17--
7
16
16:
L
_ J _
_ 1 15.37 cfs
15--
14
13
11
12
1 I
I
1
11
N 10�I
. 9-/
8
1
L
_J
a
7
I
5
II
4
I
I I
I
I
T
-I
I-
3
t 1
1-
-i
2
— —
-4 —
—I-
1
-1 _ _I_ _ L
- - I i Type 1124ohr
O;Y N
r�if�51$„
Runoff Areal=7.230'ac
T T—-1—-1 _F—
tFRLMffiA/flIume=f.lf8$raf
+ - lRujnoff DgpthO1 .0-
FIaW Le#tg#h=962'
---�-- 1I T_c=23.8min_0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.13MP #27 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 28
Summary for Subcatchment 2S: Post -Development
Runoff = 44.40 cfs @ 12.01 hrs, Volume= 2.466 af, Depth> 4.09"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 10 -Yr Rainfall=5.18"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
------------1�-
1- T
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
------------1�-
1- T
1 1- T�
�e����F
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
Imo/ �{I-0µ
�� i CT� � I I
38
4 1
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
-4
—
1 L8
n= 0.013
9.8 1,588 Total
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 2S: Post -Development
Hydrograph
48
1 1
1 L
-J
I- -- 1
1 I L -1 1 L
46
44
-------t---laa.aors
T 1
1- T
------------1�-
1- T
1 1- T�
�e����F
42I
1
1
Imo/ �{I-0µ
�� i CT� � I I
38
4 1
I -k
-4
—
1 L8
36
34
—t--1—_--1-_--fi-_
—
—
I__I
—1 t-
I
RunoffArea=r�Qti�
I I 1 1
I_#�.
30
__I__I__
—1--1--1--L-1--1
_
_
1ur�olll�Cuppe�„�}th�W(af
m 28
26
+ 1
—T --1--1--T----1—
1
I
— —-1
not D
� SII'" '
�° 22
1
T
1 - -
�G c
- -Fabw Le N F� t,5W
L
20
18
- - -1 -
t 1
-1- -
1 t-
- -
-i
-1- -
I t
-1 - -I- - L - -I- - -
1 - -I--tFC=9� 8 nfln
16
T
I
_IA
12
1
L
1
I - 1
I I L -1
10
-+--1--I--4---4--
--
- --I-- � -
8
6
rt 1
- -
1 -
-
-1
1- rt
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.BMP #27 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 29
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area =
7.230 ac,
79.94% Impervious,
Inflow Depth > 4.09" for 10 -Yr event
Inflow =
44.40 cfs @
12.01 hrs,
Volume=
2.466 of
Outflow =
8.33 cfs @
12.27 hrs,
Volume=
1.861 af, Atten= 81 %, Lag= 15.9 min
Primary =
8.33 cfs @
12.27 hrs,
Volume=
1.861 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 459.70' @ 12.27 hrs Surf.Area= 22,381 sf Storage= 62,474 cf
Plug -Flow detention time= 169.8 min calculated for 1.855 of (75% of inflow)
Center -of -Mass det. time= 110.7 min ( 858.1 - 747.3 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=8.25 cfs @ 12.27 hrs HW=459.69' (Free Discharge)
L1=Culvert (Passes 8.25 cfs of 41.96 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.29 cfs @ 8.46 fps)
3=Orifice/Grate (Orifice Controls 5.21 cfs @ 6.25 fps)
=Orifice/Grate (Weir Controls 2.76 cfs @ 1.28 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27 Type 1124 -hr 10 -Yr Rainfall=5.18"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 © 2015 HydroCAD Software Solutions LLC Paqe 30
Pond 3P: BMP #27
Hydrograph
I I I I i I I I I I I I I
30 ac ■ Inflow
/ 44.40 cfs 0 Primary
n /� .. r� ■ Outflow
E Secondary
45 / I
40 / Stot�=R474 t
/ v �7
I7 I I
35 // L L L L L L L L L 1 1 1 1
N /
v 25
_ / /I
o /
E 20 / / _ _ _ _
15-/ 8.33 cfs I —
/ 8.33 ds
10 /
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.BMP #27 Type 1124 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 31
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>2.65"
Flow Length=962' Tc=23.8 min CN=70 Runoff=20.84 cfs 1.599 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>4.96"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=53.27 cfs 2.989 of
Pond 3P: BMP #27 Peak Elev=460.01' Storage=69,592 cf Inflow=53.27 cfs 2.989 of
Primary=20.74 cfs 2.372 of Secondary=0.00 cfs 0.000 of Outflow=20.74 cfs 2.372 of
Total Runoff Area= 14.460 ac Runoff Volume= 4.588 of Average Runoff Depth =3.81"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type // 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 32
Summary for Subcatchment 1 S: Pre -Development
Runoff = 20.84 cfs @ 12.18 hrs, Volume= 1.599 af, Depth> 2.65"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 25 -Yr Rainfall=6.13"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
- + -
-1-
- =1 - -1�=/_ = r pQry��� �
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
♦�
rr
25Ty i r
18
- + - -I -
Woodland Kv= 5.0 fqs
23.8 962 Total
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff
Subcatchment 1S: Pre -Development
Hydrograph
23
22
- rt
-
20
- - - -1- T1 -
-1- - _
- + -
-1-
- =1 - -1�=/_ = r pQry��� �
♦�
rr
25Ty i r
18
- + - -I -
- I- - 4-
- + -
-1
1 - -I
17
16
rt 1
1
1
1
1
hoaw'r�11��^I
-_ 1�nlLf/'�re�/.51tic
1 1 1 1 1 1
14
- - - -I -
- I- - I
_ I -
- I
+1 #
1 RunofflVoh rnsC 1 .1599_9 a1
X12
=+--1--1==
=�==11-
+++�1���cfDPth;a*
�° 10
= _ _' _
=1= = t
= _
+1
-� --1�1ov�i te�ngth=967
=1
I I
I
I
I T I I
9
8
1
1
--� fico -218 -min-
6
---1--1---�--1
----�-�-
7V
-+--
4--+--1
-+--4-
5
4
- t -
_r
T
- -1 -
1
-1-
- - - - - --1-
3
- _ - -
- - - - - - - - - -
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.13MP #27 Type // 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 33
Summary for Subcatchment 2S: Post -Development
Runoff = 53.27 cfs @ 12.01 hrs, Volume= 2.989 af, Depth> 4.96"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 25 -Yr Rainfall=6.13"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
-T-
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
-T-
m 35
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
_o
LL 25
20
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
15-
n= 0.013
9.8 1,588 Total
Subcatchment 2S: Post -Development
Hydrograph
■ Runoff
55
-t
50
45-
40-/
-T-
m 35
—
v 30
1—
—4- —1—-1 1
_o
LL 25
20
15-
t — — — -
10
1
I
Type-11-24hr
- -1 25 -Yr RainfaHr6.11 "
--R-unoff Area -T.230 ac
I I
FRu-n-off Volume=2.1989 of
RunO Dgpth�-4-6"
- Flow Lenpft=�1,588'
9�8 min
L - -ON=93
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.BMP #27 Type 1124 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 34
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area =
7.230 ac,
79.94% Impervious,
Inflow Depth > 4.96" for 25 -Yr event
Inflow =
53.27 cfs @
12.01 hrs,
Volume=
2.989 of
Outflow =
20.74 cfs @
12.16 hrs,
Volume=
2.372 af, Atten= 61%, Lag= 9.5 min
Primary =
20.74 cfs @
12.16 hrs,
Volume=
2.372 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 460.01' @ 12.16 hrs Surf.Area= 22,921 sf Storage= 69,592 cf
Plug -Flow detention time= 154.9 min calculated for 2.372 of (79% of inflow)
Center -of -Mass det. time= 99.7 min ( 844.1 - 744.3 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=20.31 cfs @ 12.16 hrs HW=460.00' (Free Discharge)
L1=Culvert (Passes 20.31 cfs of 42.79 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.30 cfs @ 8.87 fps)
3=Orifice/Grate (Orifice Controls 5.66 cfs @ 6.79 fps)
=Orifice/Grate (Weir Controls 14.35 cfs @ 2.22 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27
Type 11 24 -hr 25 -Yr Rainfall=6.13"
Prepared by McKim & Creed
Printed
1/15/2018
HydroCAD® 10.00-15
s/n 04927 © 2015 HydroCAD Software Solutions LLC
Paqe 35
Pond 3P: BMP #27
Hydrograph
I I I
I
i I I I I I I I I
—+-4-4--
■ Inflow
53.27 cfs
_ tnfI I /�_., I � I
I�� a ��+
Outflow
0 primary
I��r •L
■ Secondary
55 '
fi F�eak�Ievt4�j0.61T
r
50
—�—
—-1—-T
Storaalle-695192 of
—1 — —T
45 , ,
1 T T 7 rt
L L L
L
L L L L L 1 1 1 1
40
y 35 ,I
30 i ,
20.74 ds
_O
LL 25 / ,
_
_ _ _ _ _ _
_ _ _ _ _ _ _ _ _
zo.7a cts 1 1 1 1 1
20 ,
LLLLi
- fififitt15�
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

2018.01.11.BMP #27 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 36
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre -Development Runoff Area=7.230 ac 0.00% Impervious Runoff Depth>3.84"
Flow Length=962' Tc=23.8 min CN=70 Runoff=30.24 cfs 2.314 of
Subcatchment 2S: Post -Development Runoff Area=7.230 ac 79.94% Impervious Runoff Depth>6.37"
Flow Length=1,588' Tc=9.8 min CN=93 Runoff=67.55 cfs 3.836 of
Pond 3P: BMP #27 Peak Elev=460.37' Storage=78,005 cf Inflow=67.55 cfs 3.836 of
Primary=41.23 cfs 3.201 of Secondary=0.00 cfs 0.000 of Outflow=41.23 cfs 3.201 of
Total Runoff Area= 14.460 ac Runoff Volume= 6.150 of Average Runoff Depth =5.10"
60.03% Pervious = 8.680 ac 39.97% Impervious = 5.780 ac

2018.01.11.BMP #27 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 37
Summary for Subcatchment 1 S: Pre -Development
Runoff = 30.24 cfs @ 12.17 hrs, Volume= 2.314 af, Depth> 3.84"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 100 -Yr Rainfall=7.67"
Area (ac) CN Description
7.230 70 Woods, Good, HSG C
7.230 100.00% Pervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
11.2 100
0.0900
0.15
Sheet Flow,
28
1 1
1 L
Woods: Light underbrush n= 0.400 P2= 3.56"
12.6 862
0.0520
1.14
Shallow Concentrated Flow,
24
— — —
—
Woodland Kv= 5.0 fqs
23.8 962 Total
Subcatchment 1S: Pre -Development
Hydrograph
- - 1— - Type 1124�hK
D 0 Yr 0a164altF-7-. �7-
-----------------
Rundff Area -7.230 ac
R urro f f i -Vo Fu me - 2 :13 t4 -a f
R -Ono - Oth_>3.�4'_'
- -Flow L"tih_962'
1 Te=218A'min
�
T
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff
4-
32 32
30
28
1 1
1 L
_J I
26
--------------
24
— — —
—
— —
22
T
I
T 1
N 20
T1I
18
— + — —I —
—I— —
— — —I—
16—
a 14
12
— —
— — — —
— — — —
10
— _ —
8
I
I I
I I
T11T71-
6
4
—4—-1—-1—-4-
-4 I
- - 1— - Type 1124�hK
D 0 Yr 0a164altF-7-. �7-
-----------------
Rundff Area -7.230 ac
R urro f f i -Vo Fu me - 2 :13 t4 -a f
R -Ono - Oth_>3.�4'_'
- -Flow L"tih_962'
1 Te=218A'min
�
T
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

2018.01.11.13MP #27 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 38
Summary for Subcatchment 2S: Post -Development
Runoff = 67.55 cfs @ 12.01 hrs, Volume= 3.836 af, Depth> 6.37"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24 -hr 100 -Yr Rainfall=7.67"
Area (ac)
CN
Description
1.450
74
>75% Grass cover, Good, HSG C
5.780
98
Paved parking, HSG C
7.230
93
Weighted Average
1.450
20.06% Pervious Area
5.780
1.7 1,473
79.94% Impervious Area
Tc Length
Slope
Velocity
Capacity Description
(min) (feet)
(ft/ft)
(ft/sec)
(cfs)
8.1 115
0.0950
0.24
Sheet Flow,
Grass: Dense n= 0.240 P2= 3.56"
1.7 1,473
0.0230
14.31
101.15 Pipe Channel,
36.0" Round Area= 7.1 sf Perim= 9.4' r= 0.75'
n= 0.013
9.8 1,588 Total
Subcatchment 2S: Post -Development
Hydrograph
75 +11L+1—+ + L
701 1 1 1 1 1 67.55 ors I
65 1 1 1 1 1 1 1 1 1 1 Type 11 -24oIh r
60 _+----11__+--4-_11 k--'100Yrl ainfaH1F7.�7��
55 _I _ _ 1 1 _ Runoff Area-?-= 6e
50 r} r}�
45 1 1 Run-off Vollume=a.1$36�f
X40-t--1--1--fi-�--1 r--1 R�noffD�pth6.�7.;
—-L—-1—-1—— —-j—-1 —-1————
`0 35 — 1 — —I — — I— — — 1 — — _I -FJb-1A� Le-npth"1,58�
30 1 1 1 1 1
25
+ - - T � 1- 1 r TIc-9 �8 -m in
20
15
10
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■Runoff

2018.01.11.BMP #27 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Page 39
Summary for Pond 3P: BMP #27
[82] Warning: Early inflow requires earlier time span
Inflow Area = 7.230 ac, 79.94% Impervious, Inflow Depth > 6.37" for 100 -Yr event
Inflow =
67.55 cfs @
12.01 hrs,
Volume=
3.836 of
Outflow =
41.23 cfs @
12.11 hrs,
Volume=
3.201 af, Atten= 39%, Lag= 6.5 min
Primary =
41.23 cfs @
12.11 hrs,
Volume=
3.201 of
Secondary =
0.00 cfs @
5.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 460.37' @ 12.11 hrs Surf.Area= 23,582 sf Storage= 78,005 cf
Plug -Flow detention time= 136.7 min calculated for 3.200 of (83% of inflow)
Center -of -Mass det. time= 87.7 min ( 828.6 - 740.9 )
Volume
Invert Avail.Storage
Storage
Description
#1
456.50' 118,838 cf
Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation
Surf.Area Inc.Store
Cum.Store
(feet)
(sq -ft) (cubic -feet)
(cubic -feet)
456.50
15,132
0
0
457.00
17,885
8,254
8,254
458.00
19,517
18,701
26,955
459.00
21,189
20,353
47,308
460.00
22,902
22,046
69,354
461.00
24,728
23,815
93,169
462.00
26,610
25,669
118,838
Device Routing Invert Outlet Devices
#1
Primary
451.00'
24.0" Round Culvert
L= 53.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 451.00'/ 450.00' S=0.0189'/' Cc= 0.900
n=0.013 Concrete pipe, bends & connections, Flow Area= 3.14 sf
#2
Device 1
456.50'
2.5" Vert. Orifice/Grate C= 0.600
#3
Device 1
457.80'
24.0" W x 5.0" H Vert. Orifice/Grate C= 0.600
#4
Device 1
459.54'
42.0" x 42.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#5
Secondary
460.50'
10.0' long x 22.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
Primary OutFlow Max=40.34 cfs @ 12.11 hrs HW=460.36' (Free Discharge)
L1=Culvert (Passes 40.34 cfs of 43.73 cfs potential flow)
2=Orifice/Grate (Orifice Controls 0.32 cfs @ 9.33 fps)
3=Orifice/Grate (Orifice Controls 6.15 cfs @ 7.38 fps)
=Orifice/Grate (Weir Controls 33.87 cfs @ 2.96 fps)
Secondary OutFlow Max=0.00 cfs @ 5.00 hrs HW=456.50' (Free Discharge)
L5=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)

2018.01.11.BMP #27 Type 1124 -hr 100 -Yr Rainfall=7.67"
Prepared by McKim & Creed Printed 1/15/2018
HydroCAD® 10.00-15 s/n 04927 @2015 HydroCAD Software Solutions LLC Paqe 40
N
3
0
LL
75
,
70
/
65
/
60
/
55
50
45
40
35
30
,
25
,
20
i
15
10 '
/
Pond 3P: BMP #27
Hydrograph
---t--1--r I I I -t -t -t -t --t-
- — ♦ — — — + + — + — + — + — + — + — + — —
6fll 15
nilpw ,Area- .-2 0 43c
- 111eA CI��I 40&.17
I �y�C
- - - Stot�=78,005 -d
I 1 1 I I I
—— 41.23 cfs T T T T T T T
t 41.23 cfs t t t t t t
l + + + + 4 4
I I I I I I I I I I I
- - - - - - - - - - - - - - -
I I I I I I I I I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Outflow
■ Primary
■ Secondary

DATE: 01 /15/2018
DESIGNED BY: GCA
(PROJECT NAME: Briar PROJECT LOCATION: Chatham Co - SDuntv. NC 102735-0165 West PROJECT O: (CHECKED BY: BSS 1
Pond Name=
BMP #27
Riser Outer Width =
4.5 ft
Riser Resisting Force =
10,848 Ib
Riser Outer Length =
4.5 ft
Base Resisting Force =
7,922 Ib
Riser Inner Width =
3.5 ft
Total Resisting Force =
18,770 Ib
Riser Inner Length =
3.5 ft
Riser Height =
9.04 ft
Riser Buoyant Force =
11,423 Ib
Base Buoyant Force =
3,296 Ib
Concrete Base Length =
6.5 ft
Total Buoyant Force =
14,718 Ib
Concrete Base Width =
6.5 ft
Concrete Base Depth =
15 in
Factor of Safety
1.28 Design Acceptable