20050732 Ver 23_Individual_20120619

THE JOHN R. McADAMS COMPANY, INC
LETTER OF TRANSMITTAL
To Annette Lucas PE
NCDENR Division of Water Quality
Wetlands & Stormwater Branch
512 N Salisbury Street 9t" Floor
Raleigh North Carolina 27604
Re Briar Chapel Phase 6 North
Final Stormwater Management Plan Submittal
I am sending you the following item(s)
Date
June 18 2012
05-015Z 00%3
** FEDERAL EXPRESS
Job No NEW 12000
COPIES
DATE
NO
DESCRIPTION
2
For review and
Final SW M mt Permit Application
2
BMP Supplement O &M Agreement
2
SW M mt Final Design Plans
2
SW M mt Final Design Calc Books
2
Proposed SW M mt Plan Approval Conditions
These are transmitted as checked below
❑
As requested
®
For approval
❑
For review and
Remarks
Copy to
❑ For your use
EJ
Signed
V
FOR INTERNAL USE ONLY
® Copy Letter of Transmittal Only to File
❑ Copy Entire Document to File
ENGINEERS PLANNERS SURVEYORS ENVIRONMENTAL
RESEARCH TRIANGLE PARK CHARLOTTE WILMINGTON
800 7.0 3646 ww%� johnmicadams coin

05-0 'I 3al u0-c3
DWQ USE ONLY
Date Received
Fee Paid
Permit Number
Applicable Rules ❑ Coastal SW —1995 ❑ Coastal SW — 2008 ❑ Ph II Post Construction
(select all that apply) ❑ Non Coastal SW HQW /ORW Waters ❑ Uruversal Stormwater Management Plan
❑ Other WQ Mgmt Plan
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form may be photocopied for use as an original
GENERAL INFORMATION
Project Name (subdivision facility or establishment name should be consistent with project name on plans
specifications letters operation and maintenance agreements etc)
Briar Chapel Phase 6 North
2 Location of Project (street address)
The project site is located off from US HWY 15 501 (west side) south of intersection of US HWY 15 501 and
Manns Chapel Road and north of intersection of US HWY 15 501 and Andrews Store Road
City
County Chatham Zip 27516
3 Directions to project (from nearest major intersection)
From intersection of US HWY 15 501 and US HWY 64, go north on US HWY 15 501 Approximately 5,000
feet north of the intersection of US HWY 15 501 and Andrews Store Road, the project site will be on the left
4 Latitude 35 49 37 N Longitude 79 06 56 W of the main entrance to the project
II PERMIT INFORMATION
1 a Specify whether project is (check one) ®New ❑Modification
b If this application is being submitted as the result of a modification to an existing permit list the existing
permit number its issue date (if known) , and the status of
construction ❑Not Started ❑Partially Completed* ❑ Completed* *provide a designer s certification
2 Specify the type of project (check one)
❑Low Density ®High Density ❑Drams to an Offsite Stormwater System ❑Other
3 If this application is being submitted as the result of a previously returned application or a letter from DWQ
requesting a state stormwater management permit application list the stormwater project number if
assigned and the previous name of the project if different than currently
proposed
4 a Additional Project Requirements (check applicable blanks information on required state permits can be
obtained by contacting the Customer Service Center at 1 877 623 -6748)
❑LAMA Major ®Sedimentation /Erosion Control 29 47 ac of Disturbed Area
❑NPDES Industrial Stormwater ®404/401 Permit Proposed Impacts Impacts to streams & 404 wetlands
b If any of these permits have already been acquired please provide the Project Name Protect /Permit Number
issue date and the type of each permit 401 Permit Briar Chapel, DWO Project #20050732, Ver 13,08/31/09
404 Permit Briar Chapel, USACE Action ID #200121252,08/21/09
Form SWU 101 Version 07Jun2010 Page 1 of 6

III CONTACT INFORMATION
1 a Print Applicant / Signing Official s name and title (specifically the developer property owner lessee
designated government official individual etc who owns the protect)
Applicant /Organization NNP Briar Chapel, LLC
Signing Official & Title Bill Mumford, Assistant Vice President
b Contact information for person listed in item 1a above
Street Address 16 Windy Knoll Circle
City Chapel Hill State NC Zip 27516
Mailing Address (if applicable)
City
State
Zip
Phone (919 ) 9510713 Fax (919 ) 9510711
Email bmumford@newlandco com
c Please check the appropriate box The applicant listed above is
® The property owner (Skip to Contact Information item 3a)
❑ Lessee* (Attach a copy of the lease agreement and complete Contact Information item 2a and 2b below)
❑ Purchaser* (Attach a copy of the pending sales agreement and complete Contact Information item 2a and
2b below)
❑ Developer* (Complete Contact Information item 2a and 2b below)
2 a Print Property Owner s name and title below if you are the lessee purchaser or developer (This is the
person who owns the property that the project is located on)
Property Owner /Organization
Signing Official & Title
b Contact information for person listed in item 2a above
Street Address
City
Mailmg Address (if applicable)
City
Phone ( )
Email
State
State
Fax
Zip
WE
3 a (Optional) Print the name and title of another contact such as the project s construction supervisor or other
person who can answer questions about the project
Other Contact Person /Organization NNP Briar Chapel, LLC
Signing Official & Title Lee Bowman, Project Manager
b Contact information for person listed in item 3a above
Mailmg Address 16 Windy Knoll Circle
City Chapel Hill State NC Zip 27516
Phone (919 ) 9510712 Fax (919 ) 9510711
Email lbowman@newlandco com
Form SWU 101 Version 07Jun2010 Page 2 of 6

4 Local jurisdiction for building permits Chatham County
Point of Contact lenny Williams
IV PROJECT INFORMATION
Phone # (919 ) 5428230
1 In the space provided below bneflv summarize how the stormwater runoff will be treated
Stormwater runoff from impervious areas associated with the development of Phase 6 North of Briar Chapel
will be captured and directed to a wet pond designed with an SA /DA ratio based upon the 90 /o TSS design
2 a If claiming vested rights identify the supporting documents provided and the date they were approved
❑ Approval of a Site Specific Development Plan or PUD Approval Date
❑ Varid Building Permit Issued Date
❑ Other Date
b If claiming vested rights identify the regulation(s) the project has been designed in accordance with
❑ Coastal SW —1995 ❑ Ph II — Post Construction
3 Stormwater runoff from this project drams to the Cape Fear River basm
4 Total Property Area 36 62 (PH6N) acres 5 Total Coastal Wetlands Area _N /A acres
6 Total Surface Water Area N/A acres
7 Total Property Area (4) — Total Coastal Wetlands Area (5) — Total Surface Water Area (6) = Total Project Area
36 62 (PH6N) acres
Total project area shall be calculated to exclude the following the normal pool of impounded structures the area
between the banks of streams and rivers the area below the Normal High Water (NHW) line or Mean High Water
(MHW) line and coastal wetlands landward from the NHW (or MHW) line The resultant project area is used to
calculate overall percent built upon area (BETA) Non coastal wetlands landward of the NHW (or MHW) line may be
included in the total project area
8 Project percent of impervious area (Total Impervious Area / Total Project Area) X 100 = Approx 37% %
9 How many drainage areas does the project have ?1 (For high density count 1 for each proposed engineered
stormwater BMP For low density and other projects use 1 for the whole property area)
10 Complete the following information for each drainage area identified in Project Information item 9 If there
are more than four drainage areas in the project attach an additional sheet with the information for each area
provided in the same format as below
Basin Information
Drainage Area 1
Drainage Area _
Drainage Area _
Drainage Area _
Receiving Stream Name
Pokeberry Creek
Stream Class *
WS-IV NSW
Stream Index Number *
16-37
Total Drainage Area (sf)
901 256
On site Drainage Area (sf)
901256
Off site Drainage Area (sf)
0
Proposed Impervious Area ** (so
446 926
% Impervious Area ** (total)
Impervious Surface Area
Drainage Area 1
Drainage Area _
Drainage Area _
Drainage Area
On site Buildings/ Lots (sf)
290 685
On site Streets (sf)
123 537
On site Parking (sf)
Inc in Streets
On site Sidewalks (so
32 704
Other on site (sf)
Future (sf)
Off site (sf)
Existing BUA * ** (sf)
Total (sf)
446 926
* Stream Class and Index Number can be determined at http & ortal ncdenr orgAveblzvqlpslcsulclasszficatzons
Form SWU 101 Version 07Jun2010 Page 3 of 6

Impervious area is defined as the built upon area including but not limited to buildings roads parking areas
sidewalks gravel areas etc
Report only that amount of existing BUA that will remain after development Do not report any existing BUA that is
to be removed and which will be replaced by new BUA
11 How was the off site impervious area listed above determined? Provide documentation N/A all impervious
is from onsite sources, which was measured based upon proposed development plan
Projects m Union County Contact DWQ Central Office staff to check of the project is located within a Threatened &
Endangered Species watershed that maybe subject to more stringent stormwater requirements as per NCAC 02B 0600
V SUPPLEMENT AND O &M FORMS
The applicable state stormwater management permit supplement and operation and maintenance (O &M) forms
must be submitted for each BMP specified for this project The latest versions of the forms can be downloaded
from htto / /mortal ncdenr ore /web /wa /ws /su /bmo manual
VI SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ)
A complete package includes all of the items listed below A detailed application instruction sheet and BMP
checklists are available from http / /portal ncdenr org /web /wq /ws /su /statesw /forms_docs The complete
application package should be submitted to the appropriate DWQ Office (The appropriate office may be
found by locating project on the interactive online map at http / /portal ncdenr org /web /wq /ws /su /maps )
Please indicate that the following required information have been provided by initialing in the space provided
for each item All original documents MUST be signed and mitialed in blue ink Download the latest versions
for each submitted application package from http //portal ncdenr org /web /wq /ws /su /statesw /forms_docs
Initials
1 Original and one copy of the Stormwater Management Permit Application Form
2 Original and one copy of the signed and notarized Deed Restrictions & Protective Covenants NIA - 5VE PRIW
Form (if required as per Part VII below) KAOrr C64W
3 Original of the applicable Supplement Form(s) (sealed, signed and dated) and O &M -JF A""W
agreement(s) for each BMP
4 Permit application processing fee of $505 payable to NCDENR (For an Express review refer to
http / /www envhelp org /pages /onestopexpress html for information on the Express program
and the associated fees Contact the appropriate regional office Express Permit Coordinator for
additional information and to schedule the required application meeting )
5 A detailed narrative (one to two pages) describing the stormwater treatment /management for
the project This is required in addition to the brief summary provided in the Project
Information item 1
6 A USGS map identifying the site location If the receiving stream is reported as class SA or the
receiving stream drams to class SA waters within Y2 mile of the site boundary include the Vz
mile radius on the map
7 Sealed signed and dated calculations
8 Two sets of plans folded to 8 5 x 14 (sealed signed & dated) including
a Development /Project name
b Engineer and firm
c Location map with named streets and NCSR numbers
d Legend
e North arrow
f Scale
g Revision number and dates
h Identify all surface waters on the plans by delineating the normal pool elevation of
impounded structures the banks of streams and rivers the MHW or NHW line of tidal
waters and any coastal wetlands landward of the MHW or NHW Imes
• Delineate the vegetated buffer landward from the normal pool elevation of impounded
structures the banks of streams or rivers and the MHW (or NHW) of tidal waters
i Dimensioned property /project boundary with bearings & distances
) Site Layout with all BUA identified and dimensioned
k Existing contours proposed contours spot elevations finished floor elevations
1 Details of roads drainage features collection systems and stormwater control measures
in Wetlands delineated or a note on the plans that none exist (Must be delineated by a
qualified person Provide documentation of qualifications and identify the person who
made the determination on the plans
Form SWU 101 Version 07Jun2010 Page 4 of 6
JN /A
If

n Existing drainage (including off site) drainage easements pipe sizes runoff calculations
o Drainage areas delineated (included in the main set of plans not as a separate document)
p Vegetated buffers (where required)
9 Copy of any applicable soils report with the associated SHWT elevations (Please identify WT (PROW
elevations in addition to depths) as well as a map of the boring locations with the existing
elevations and boring logs Include an 8 5 x11 copy of the NRCS County Soils map with the
project area clearly delineated For projects with infiltration BMPs the report should also
include the soil type expected infiltration rate and the method of determining the infiltration rate
(Infiltration Devices submitted to WiRO Schedule a site visit for DWQ to verify the SHWT prior
to submittal [phone] )
10 A copy of the most current property deed Deed book Page No Ndr *&'go
11 For corporations and limited liability corporations (LLC) Provide documentation from the NC
Secretary of State or other official documentation which supports the titles and positions held
by the persons listed in Contact Information item 1a 2a and /or 3a per NCAC 2H 1003(e) The
corporation or LLC must be listed as an active corporation in good standing with the NC
Secretary of State otherwise the application will be returned
http / /www secretary state nc us /Corporations /CSearch aspx
VII DEED RESTRICTIONS AND PROTECTIVE COVENANTS
For all subdivisions outparcels and future development the appropriate property restrictions and protective
covenants are required to be recorded prior to the sale of any lot If lot sizes vary significantly or the proposed
BUA allocations vary a table listing each lot number lot size and the allowable built upon area must be provided
as an attachment to the completed and notarized deed restriction form The appropriate deed restrictions and
protective covenants forms can be downloaded from
http /portal ncdenr org /web /wq/ws /su /statesw /forms docs Download the latest versions for each submittal
In the instances where the applicant is different than the property owner it is the responsibility of the property
owner to sign the deed restrictions and protective covenants form while the applicant is responsible for ensuring
that the deed restrictions are recorded
By the notarized signature(s) below the permit holder(s) certify that the recorded property restrictions and
protective covenants for this project if required shall include all the items required in the permit and listed
on the forms available on the website that the covenants will be binding on all parties and persons claiming
under them that they will run with the land that the required covenants cannot be changed or deleted
without concurrence from the NC DWQ and that they will be recorded prior to the sale of any lot
VIII CONSULTANT INFORMATION AND AUTHORIZATION
Applicant Complete this section if you wish to designate authority to another individual and /or firm (such as a
consulting engineer and /or firm) so that they may provide information on your behalf for this project (such as
addressing requests for additional information)
Consulting Engineer Jeremy V Finch, PE
Consulting Firm EcoEngmeermg (A Division of The John R McAdams Company Inc)
Mailing Address PO Box 14005
City Research Triangle Park
Phone (919 ) 3615000
Email jfmch@ecoengr com
State NC Zip 27709
Fax (919 ) 3612269
IX PROPERTY OWNER AUTHORIZATION (if Contact Information item 2 has been filled out complete this
section)
I (print or type name of person listed in Contact Information item 2a) , certify that I
m
own the property identified this permit app icathon and thus give permission to (print or type name of person
listed in Contact Information item 1a) with (print or type name of organization listed in
Contact Information item 1a) to develop the project as currently proposed A copy of
the lease agreement or pending property sales contract has been provided with the submittar which indicates the
party responsible for the operation and maintenance of the stormwater system
Form SWU 101 Version 07Jun2010 Page 5 of 6

As the legal property owner I acknowledge understand and agree by my signature below that if my designated
agent (entity listed in Contact Information item 1) dissolves their company and /or cancels or defaults on their
lease agreement or pending sale responsibility for compliance with the DWQ Stormwater permit reverts back to
me the property owner As the property owner it is my responsibility to notify DWQ immediately and submit a
completed Name /Ownership Change Form within 30 days otherwise I will be operating a stormwater treatment
facility without a valid permit I understand that the operation of a stormwater treatment facility without a valid
permit is a violation of NC General Statue 143 2151 and may result in appropriate enforcement action including
the assessment of civil penalties of up to $25 000 per day pursuant to NCGS 143 215 6
Signature
a Notary Public for the State of
do hereby certify that
before me this _ day of
Date
County of
personally appeared
and acknowledge the due execution of the application for
a stormwater permit Witness my hand and official seal
SEAL
My commission expires
X APPLICANTS CERTIFICATION
I (print or type name of person listed in Contact Information item 1a) ULU-AAI' 3 MU+iFc�20
certify that the information included on this permit application form is to the best of my knowledge correct and
that the project will be constructed in conformance with the approved plans that the required deed restrictions
and protective covenants will be recorded and that the proposed project complies with the requirements of the
applicable stormwater rules under 15A NCAC 2H 1000 SL 2006 246 (Ph II - Post Construction) or SL 2008 211
Signature Date & 04 to 17-
I
Q,o 61X� a Notary Public for the State of NzW�aCA YD L County of
AAecweinloux do hereby certify that 4)klu ju S M i nr.-A YA personally appeared
before me this -Way of TIA XNX , 17,and ac
ho
wledge the due execution of the application for
a Stormwater permit Witness my hand and official seal
W
SEAL
My commission expires_! I a 1
Form SWU 101 Version 07Jun2010 Page 6 of 6

Permit No
(to be pro ded by DWQ)
AV O�O� W ATF9OG
A r
NCDENR o
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 III) must be printed filled out and submitted along with all of the required information
I PROJECT INFORMATION
Project name
Bnar Chapel Phase 6 North
Contact person
Jeremy V Finch PE
Phone number
919 361 5000
Date
6/14/2012
Drainage area number
1
II DESIGN INFORMATION
Site Charactenstics
Drainage area
901 256 fe
Impervious area post development
446 926 fe
/ Impervious
4959 /
Design rainfall depth
10 In
Storage Volume Non SA Waters
Minimum volume required
Volume provided
Storage Volume SA Waters
15 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 deanout 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
37 264 ft"
80105 ft3 OK volume provided Is equal to or in excess of volume required
ft3
ft3
ft3
ft3
N (Y or N)
in
(unifless)
(unifless NOVE
in/hr
N/A ft3/sec
N/A ft3lsec
#VALUE' ft3lsec
474 50 fmsl
47200 fmsl
N/A fmsl
47250 fmsl
47150 fmsl
46600 fmsl
46500 fmsl
100 ft
Y (Y or N)
474 5 fmsl
of ftw eov*01- of I -YL 7,q-m4 tw#"
(f RtW11100 &( DIY w�T
" If pelf w 78 stab ^0 sia►-
I f �' 1t% se f;'R IN It f
wrA cuenw1 cawm
Data not needed for calculation option #1 but OK if provided
Data not needed for calculation option #1 but OK if provided
OK
Forth SW401 Wet Dete t on Bas n Re 9- 4118112 Parts I & 11 Design S mmary Page 1 of 2

II DESIGN INFORMATION
Surface Areas
Area temporary pool
Area REQUIRED permanent pool
SA/DA ratio
Area PROVIDED permanent pool Aw„_j.
Area bottom of 1 Oft vegetated shelf Abot �,en
Area sediment cleanout top elevation (bottom of pond) AWLmd
Volumes
Volume temporary pool
Volume permanent pool VPL,,,-Pw
Volume forebay (sum of forebays 9 more than one forebay)
Forebay / of permanent pool volume
SA/DA Table Data
Design TSS removal
Coastal SA/DA Table Used?
Mountain/Piedmont SAIDA Table Used?
SA/DA ratio
Average depth (used in SAIDA table)
Calculation option 1 used? (See Figure 10 2b)
Volume permanent pool Vp--Pw
Area provided permanent pool Ap.,r,_pw
Average depth calculated
Average depth used in SA/DA dam, (Round to nearest 0 5ft)
Calculation option 2 used? (See Figure 10 2b)
Area provided permanent pool Ace,,,,,,,
Area bottom of 10ft vegetated shelf ki �nen
Area sediment cleanout top elevation (bottom of pond) AnoLce„d
Depth (distance b/w bottom of 1 Oft shelf and top of sediment)
Average depth calculated
Average depth used in SAIDA d.„ (Round to down to nearest 0 5ft)
Drawdown Calculations
Drawdown through onfice?
Diameter of onfice (if circular)
Area of onfice (if non - circular)
Coefficient of discharge (Cc)
Driving head (H )
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 onfice 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 & onficel
Freeboard provided
Vegetated filter provided?
Recorded drainage easement provided?
Capures all runoff at ultimate build -out?
Drain mechanism for maintenance or emergencies is
Permit No
(to be pro ded by DWG)
34 957 fe
23 072 fe
256 (unitless)E SAICA AMA N,N I#JVfC~
25 869 fe OK CoAMw (gar pawofi) ** Mot
22 332 ft`
11880 fe
80105 1`0 OK
99 911 ft3
24103 ft3
241/ / Insufficient forebay volume
90 A
N (Y or N)
Y (Y or N)
T5-6 ( unitless)
Y (Y or N)
99 911 ft'
25 869 ft1
ft Need 3 It min
It
(Y or N)
25 869 ft`
22 332 ft`
11880 fe
5 50 It
3 86 It
39ft
Y (Y or N)
3 00 in
in
0 60 ( unitless)
037ft
N (Y or N)
( unitless)
(unitless)
ft
ft
N/A ft3 /sec
N/A ft3 /sec
014 ft3 /sec
OK
OK,!�— 5A10A Imp &cod UuMA~ OW L w
a##jIrto CWr Soto) nY& 00"
2 99 days OK draws down in 2 5 days
3 1
OK
10 1
OK
100 It
OK
3 1
OK
30 1
OK
Y (Y or N)
OK
11 ft
OK
N (Y or N)
OK
Y (Y or N)
OK
Y (Y or N)
OK
8 DIP drain pipe w/ valve operable from top of nser
Form SW401 Wet Detention Bas n Re 9-4118/12 Parts I & 11 Des g Summary Page 2 of 2

d A
Permit No
III REQUIRED ITEMS CHECKLIST
(to be provided by D WQ)
Please Indicate the page or plan sheet numbers where the supporting documentation can be found An incomplete submittal package will
result In a request for additional Information This will delay final review and approval of the prdject Initial in the space provided to
Indicate the following design requirements have been met If the applicant has designated an agent the agent may Initial below If a
requirement has not been met attach justification
Form SW401 Wet Detention Basin Rev 9- 4/18/12 Part III Required Items Checklist Page 1 of 1
Page/ Plan
Initials
Sheet No
?F
C;4
1 Plans (1 50 or larger) of the entire site shoving
C11
Design at ultimate build out
G.11 _ _
Off site drainage (if applicable)
5 5W if
Delineated drainage basins (include Rational C coefficient per basin)
Basin dimensions
Pretreatment system
High flow bypass system
Maintenance access
Proposed drainage easement and public right of way (ROW)
Overflow device and
Boundaries of drainage easement
�'-
2 Partial plan (1 = 30 or larger) and details for the wet detention basin showing
Outlet structure with trash rack or similar
Maintenance access
Permanent pool dimensions
Forebay and main pond with hardened emergency spillway
Basin cross section
Vegetation specification for planting shelf and
Filter strip
' 2
3 Section view of the wet detention basin (1 = 20 or larger) showing
Side slopes 31 or lower
Pretreatment and treatment areas and
Inlet and outlet structures
''-
4 If the basin is used for sediment and erosion control during construction clean out of the basin is specified
on the plans prior to use as a wet detention basin
t SF ?
fO EICA
—
5 A table of elevations areas incremental volumes & accumulated volumes for overall pond and for forebay
to verify volume provided
6 A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized
NWA
7 The supporting calculations
P"kW
IAJ 44C 641111111114
8 A copy of the signed and notarized operation and maintenance (0 &M) agreement
NIP
NIA
9 A copy of the deed restrictions (if required)
CIA
_ MIA
10 A sods report that is based upon an actual field investigation sod borings and infiltration tests County
soil maps are not an acceptable source of soils information
Nd11E- SW-;W U. W #f RWOW $Je- pbo.0 lit WMW &+ "W ltfW&9t
Sl��aft ICE 9111111111illm W fo $MUT' IS Ex&lft 1a dt- M*W
ee& *to& j,�pl0,IM i f fue IN TM; &0eftoov
Form SW401 Wet Detention Basin Rev 9- 4/18/12 Part III Required Items Checklist Page 1 of 1

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
This system (check one)
❑ does ® does not
incorporate a vegetated filter at the outlet
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 m,mmized 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 10 inches (or 15 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
Potential problem
How I will remediate the problem
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 mches
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
Potential problem
How I will remediate the problem
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
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 algal growth
Cattails phragmites or other
Remove the plants by wiping them
invasive plants cover 50% of
with pesticide (do not spray)
the basm 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
Potential problem
How I will remediate the problem
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
Cloggmg 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 deternune 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 feet in the main pond, the
sediment shall be removed
When the permanent pool depth reads feet in the forebay, the sediment
shall be removed
Sediment Removal
Bottom
46600
BASIN DIAGRAM
(fill in the blanks)
f ft Min
Sediment
Storage
Pool
Permanent Pool Elevation 472 00
Sediment Removal Elevation 466 00 j Volume
Bottom Elevation 465 00 11 ft
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 Phase 6 North
BMP drainage area number Wet Pond
Print name Bill Mumford, PE
Title Assistant Vice President NNP Briar Chapel LLC
Address 16 Windy Knoll Circle Chapel Hill, NC 27516
Phone [phone]
Signature 6t w.Ad l,.
Date 1- t 4 - toy
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 —�[4 � r w a Notary Public for the State of
�f 0
C�axpL-y-a, County of Wen6urq do hereby certify that
Q.M S personally appeared before me this
day of TLLAe, aol a., and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements Witness my hand and official
seal d" 0-
SEAL
My commission expires
Form SW401 Wet Detention Basin O &M Rev 4 Page 4 of 4

PROPOSED BRIAR CHAPEL PHASE 6N DWO PERMIT CONDITIONS
1 The plans and specifications for Phase 6N approved by DWQ are incorporated by reference into this
approval and are enforceable by DWQ, provided however, that any modification to the design of the
stormwater management system reflected in the as built certification for the system that is accepted by
DWQ shall take precedence over the original plans and specifications
2 All stormwater management devices shall be located in either public rights of way dedicated common
areas, or recorded easement areas The final plats for the project showing all such rights of way,
common areas, and easement areas, in accordance with the approved plans
3 The stormwater management system for Phase 6N which includes one (1) wet detention pond, and the
signed and notarized Operation and Maintenance Agreement as approved by this office, and the
drainage patterns depicted on the plan sheets, must be maintained in perpetuity No changes to the
structural stormwater practices shall be made without written authorization from DWQ The stormwater
management conveyances, detention and treatment structures shall have maintenance access and at least
10 foot drainage easement on each side to allow for the ability to maintain the structures and to perform
corrective actions The stormwater easement shall be recorded to provide protection of the structures
from potential alterations by future property owners
4 All operation maintenance activities shall be followed as stipulated in the Operation and Maintenance
Agreement signed by you and notarized on 2012 and received in our office on 2012
5 The applicant and/or authorized agent shall provide a completed Certification of Completion Form to the
DWQ 401 Program within ten (10) days of the project completion
6 The applicant shall submit three (3) copies of executed Deed Restrictions and Protective Covenants
within thirty (30) days of recording with the Register of Deeds, Chatham County, North Carolina The
applicant shall cause a copy of the executed Deed Restrictions and Protective Covenants to be provided
to all lot owners in Phase 6N
7 In lieu of the property restrictions and protective covenants referred to in and required by DWQ s
Stormwater Management Permit Application Form (Section VII ), the Deed Restrictions and Protective
Covenants required by Condition 6 shall limit the maximum built upon area (BUA) for each drainage
area in Phase 6N as follows
Drainage Area (SF)
Maximum Allowable BUA (SF)
I Drainage Area 1 (To Wet Detention Pond)
901 256
446 926
Note Built upon area (BUA) includes but is not limited to roofed structures asphalt concrete gravel
brick stone slate coquina and parking areas but does not include raised uncovered open slat
decking or the water surface of swimming pools
US2000 12449463 3

8 Until the project is completed (i a full build out has occurred) and the development common areas have
been transferred to the Homeowner's Association (HOA), the applicant shall be responsible for
verifying that the total (BUA) within each drainage area identified in Condition 7 does not exceed the
maximum allowed by this approval and by the Deed Restrictions and Protective Covenants To comply
with this condition, the applicant shall be responsible for reviewing and tracking all new lot
construction, for the purpose of maintaining compliance with the allowable BUA limits within each
drainage area The plans reviewed by the applicant must show all proposed BUA The applicant shall
keep copies of all approved lot construction plans for the purposes of recordkeepmg and auditing and
shall make those records available to DWQ upon request
9 Once the project is completed (i a full build out has occurred) the applicant shall transfer to the HOA
responsibility for the stormwater management system serving Phase 6N and for ensuring compliance
with the conditions contained in this approval The HOA shall carry out these responsibilities through an
Architectural Review In connection with the transfer of such responsibilities the applicant shall ensure
that the HOA is aware of and understands the constructed stormwater treatment system, the maximum
BUA allowed by the permit the executed Deed Restrictions and Protective Covenants, and its
responsibility for meeting the BUA limitations
10 The applicant shall submit to DWQ and shall have received approval for revised plans specifications,
and calculations prior to construction, for any significant modification to the approved plans, including,
but not limited to those listed below
a Addition to the approved amount of built upon area to a BMP
b Further subdivision acquisition, or sale of all or part of the project area
c Transfer of ownership
Upon receipt of a proposed revision(s), DWQ shall advise the applicant as to the appropriate
review /approval process
US2000 12449463 3

LIMITED LIABILITY COMPANY
v A ANNUAL REPORT
NAME OF LMTED LIABILITY COMPANY NNP Briar Chapel LLC
SECRETARY OF STATE L L C ID NUMBER 0631973
NATURE OF BUSINESS Real Estate Development
REGISTERED AGENT National Registered Agents Inc
REGISTERED OFFICE MAILING ADDRESS 120 Penmarc Drive
Raleigh NC 27603
E Filed Annual Report
1-05468752
Do not data enter manually
STATE OF INCORPORATION DE
REGISTERED OFFICE STREET ADDRESS 120 Penmarc Drive
Raleigh NC 27603 Wake County
PRINCIPAL OFFICE TELEPHONE NUMBER 8584557503
PRINCIPAL OFFICE MAILING ADDRESS
PRINCIPAL OFFICE STREET ADDRESS
MANAGERS/MEMBERS /ORGANIZERS
Aame Newland National Partners LP
Title Manager
Address
9820 Towne Centre Drive Suite 100
San DteQo CA 92121
9820 Towne Centre Drive Suite 100
San Diego CA 92121
9820 Towne Centre Drive Suite 100
San Diego CA 92121
CERTIFICATION OF ANNUAL REPORT MUST BE COMPLETED BY ALL LMTED LIABILITY COMPANIES
Newland National Partners LP
FORM MUST BE SIGNED BY A MANAGER/MEMBER
Dolores A Valle
04/15/2011
DATE
Manager
TYPE OR PRINT NAME TYPE OR PRINT TITLE
ANNUAL REPORT FEE $200 NvLAIL TO Secretary of State Corporations Division Post Office Box 29525 Raleigh, NC 27626 -0525

EcoEngineering
A division ofThe John R McAdams Company Inc
Ds - fl '73 a. ua 3
CHATHAM COUNTY NORTH CAROLINA
FINAL STORMWATER MANAGEMENT PLAN DESIGN
NEW -12000
June 2012
Jeremy V Finch PE
Project Manager
Research Triangle Park NC
Post Office Box 14005
Reseach Triangle Park,
North Carolina 27709
2905 Meridian Parkway
North Carolina 27713
5646
91 m-&W -4262
919361 7269 Fax
wwwecoengrcorn I Design Services Focused On Client Success

BRIAR CHAPEL — PHASE 6 NORTH
Final Stormwater Management Plan Design
General Descrinnon
Located off of US Highway 15 501, north of Andrews Store Road and south of Mann s Chapel Road in
Chatham County, NC is the proposed development known as Briar Chapel Phase 6 North of the
proposed development is approximately 37 acres and will consist of the construction of single family
lots along with the associated utility, parking and roadway infrastructure
The overall proposed Briar Chapel development is located within the Cape Fear River Basin, and
drains to a stream (Pokeberry Creek) classified as Water Supply IV (WS IV), and Nutrient Sensitive
Waters (NSW) As a result of the proposed development exceeding the maximum allowable limit for
stream impacts, an individual permit issued by The United States Army Corps of Engineers (USACE)
was required (Clean Water Act Section 404 permit) Also, a Clean Water Act Section 401 Water
Quality Certification from NCDWQ was attached to the individual permit Under the 401 Water
Quality Certification issued by NCDWQ, the proposed site will be required to comply with the
following stormwater management requirements
I A final written stormwater management plan for each subwatershed (including signed and
notarized Operation and Maintenance agreements) shall be submitted to the 401 Oversight
and Express Permitting Unit The stormwater management plan maybe submitted to DWQ
in phases for written approval as long as no impact to wetlands or streams occur in that
phase until written approval is received from DWQ
2 The stormwater plans shall utilize constructed wetlands bioretention areas wet ponds
followed by forested filter strips and similar best management practices designed to remove
nutrients The stormwater management plan must include plans specifications and
worksheets for stormwater management facilities that are appropriate for the surface water
classification and designed to remove at least 85% TSS according to the most recent
version of the NCDENR Stormwater Best Management Practices Manual
3 For low density areas of the project with low impervious surface area engineered
stormwater management facilities are not expected For these areas of lower impervious
area similar best management practices that remove nutrients such as grassed swales and
vegetated riparian buffers should be sufficient rather than more intensive engineered
stormwater devices such as constructed wetlands
In addition to the above DWQ stormwater requirements the following stormwater quality and quantity
items are required per Section 8 3 (` Stormwater Controls ) of the Chatham County Compact
Communities Ordinance
1 Control and treat the first inch of runoff from the project site and from any offsite drainage
routed to an on -site control structure Ensure that the draw down time for this treatment
volume is a minimum of forty eight (48) hours and a maximum of one hundred and twenty
(120) hours
2 Maintain the discharge rate for the treatment volume at or below the pre- development
discharge rate for the 1-year 24 -hour storm
The proposed stormwater management plan for Phase 6 North of Briar Chapel will be designed to protect the
downstream environment The plan incorporates biologically based stormwater management techniques to
manage both water quantity and quality aspects of site runoff As can be seen in this report stormwater

management for Phase 6 North will be accomplished by incorporating an engineered stormwater best
management practice facility to capture and treat the stormwater runoff from developed areas The specific
stormwater treatment device that will be used is a wet detention basin designed to remove a minimum of 90%
average annual total suspended solids (TSS) provide slow release (i e 2 to 5 days) of the difference in pre to
post development peak runoff rate for the 1 year 24 hour storm This report contains the final design
calculations for the proposed wet detention basin located in Phase 6 North of Briar Chapel Please refer to the
summary of results and discussion of results sections of this report for additional information
Calculation MethodoloQv
➢ Rainfall data for the Chatham County, NC region is from NOAA Atlas 14 with a partial
duration series assumption The rainfall depths were entered into a spreadsheet that calculated a
center weighted storm based upon the NOAA Atlas 14 depths The 1 year /24 hour rainfall
depth is 2 95 inches, the 2 Year /24 hour rainfall depth is 3 56 inches the 10 Year /24 hour
rainfall depth is 5 16 inches, and the 100 year /24 hour rainfall depth is 7 62 inches All of these
computed storms were modeled within the hydrologic model Please reference the rainfall
data section within this report for additional information
➢ Using maps contained within the Chatham County Soil Survey, the watershed soils were
determined to be from hydrologic soil group (HSG) B soils Since the method chosen to
compute the post development peak flow rates and runoff volumes is dependent upon the soil
type all hydrologic calculations are based upon the assumption of HSG B soils
➢ A composite SCS Curve Number was calculated for the post development condition using SCS
curve numbers and land cover conditions Land cover conditions for the post development
condition were taken from the proposed development plan
➢ The post development time of concentration to the wet detention basin was assumed to be 5
minutes in the post development condition
➢ All on site topo was taken from a flown aerial topographic survey by others provided to The
John R McAdams Company, Inc by McKim & Creed The drainage map for the post
development condition has been included in this report
➢ PondPack Version V81, by Haestad Methods was used to generate post development peak flow
rates and generate the stage discharge rating curve for the proposed wet detention basin Final
routing calculations for the wet detention basin were also performed within Pondpack
➢ The stage storage rating curve and stage storage function for the proposed wet detention basin
was generated externally in a spreadsheet and then input into Pondpack
➢ A velocity dissipater is provided at the end of the principal spillway outlet for the wet detention
basin to prevent erosion and scour in the downstream area The dissipater is constructed using
nprap, underlain with a woven geotextile filter fabric The filter fabric is used to minimize the
loss of soil particles beneath the nprap apron The dissipater is sized for the 10 year storm event
using the NYDOT method It is a permanent feature of the outlet
A Water quality sizing calculations for each facility were performed in accordance with the N C
Stormwater Best Management Practices manual (NCDENR July 2007) The wet detention
basin surface area was sized by multiplying the drainage area to the facility by the interpolated
SA/DA ratio from the Surface Area to Drainage Area Ratio for Permanent Pool Sizing to
Achieve 90% TSS Pollutant Removal Efficiency in the Mountain & Piedmont Regions The
minimum temporary pool volume was determined by calculating the 1 inch runoff volume
using the Simple Method

Conclusion
If the development on this tract is built as proposed within this report then the requirements set forth in
the Water Quality Certification #3402 (WQC #3402) and Section 8 3 ( Stormwater Controls ) of the Chatham
County Compact Communities Ordinance will be met with the proposed wet detention basin However,
modifications to the proposed development may require that this analysis be revised Some
modifications that would require this analysis to be revised include
1 The proposed site impervious surface exceeds the amount accounted for in this report
2 The post development watershed breaks change significantly from those used to prepare this
report
The above modifications may result in the assumptions within this report becoming invalid The
computations within this report will need to be revisited if any of the above conditions become
apparent as development of the proposed site moves forward

1
SUMMARY OF RESULTS
2
USGS MAP
3
SOILS INFORMATION
4
FEMA FIRM PANEL MAP
5
RAINFALL INFORMATION
6
HYDROLOGIC CALCULATIONS
WET POND FINAL DESIGN
7
CALCULATIONS

SUMMARY OF RESULTS
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

BRIAR CHAPEL PHASE 6 NORTH SUMMARY OF RESULTS J FINCH PE
NEW 12000 6/14/2012
WET POND
Return Period
Inflow
[cfs]
Outflow
[cfs]
Max WSE
[ft]
Freeboard
[ft]
1 Year
4346
036
47439
261
2 Year
6048
220
47460
240
10 Year
9667
2441
47504
196
25 Year
11439
5033
47538
162
100 Year
13831
7098
47594
106
Design Drainage Area =
2069
acres
Design Impervious Area =
1026
acres
/ Impervious =
496/
Top of Dam =
47700
ft
Normal Pool Elevation =
47200
ft
Surface Area at NWSE =
25 869
sf
Minimum Required Surface Area at NWSE =
23 085
sf
Water Quality Volume Storage Provided =
80 105
cf
Mimmum R u►red Water Quality Volume Storage =
37 264
cf
Design Drawdown Time =
262
days
Riser Lengdi =
5
ft
Riser Width =
5
ft
Riser Crest =
47450
ft
Barrel Diameter =
30
mches
# of Barrels =
1
Invert In =
46600
feet
Invert Out =
46200
feet
Length =
83
feet
Slope =
00482
ft/ft

USGS MAP
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

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Name: m:\NC3pro \35079G1A.P24 Location: 035' 49'36.37" N 079° 06'41.37" W
Date: 3/15/2012
Scale: 1 inch equals 2000 feet
(C) 1998,

SOILS INFORMATION
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

FEMA FIRM PANEL MAP
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

RAINFALL INFORMATION
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

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HYDROLOGIC CALCULATIONS
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

BRIAR CHAPEL PHASE 6 NORTH HYDROLOGIC CALCULATIONS J FINCH PE
NEW 12000 Post Development To Wet Pond 6/14/2012
ISCS CURVE�NUMBERS ` r
Assume
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
HSG A =
00%
HSG B =
1000%
HSG C =
00%
HSG D =
00%
Cover Condition
SCS CN
Comments
Impervious
98
Open
61
Assume good condition
Wooded
55
Assume good condition
Water
100
H POST DEVELOPMENT
_> To Wet Pond
A Watershed Breakdown
Total Number of Single Family 50 Lots = 37 lots
Assumed Impervious Area Per Single Family 50 Lot = 3 500 square feet
Total Impervious Area from Single Family 50 Lots = 129 500 square feet
2 97 acres
Total Number of Single Family 60 Lots = 2325 lots
Assumed Impervious Area Per Single Family 60 Lot = 3 800 square feet
Total Impervious Area from Single Family 60 Lots = 88 350 square feet
2 03 acres
Total Number of Single Family 50 Corner Lots = 11 lots
Assumed Impervious Area Per Single Family 50 Corner Lot = 3 700 square feet
Total Impervious Area from Single Family 50 Corner Lots = 40 700 square feet
0 93 acres
Total Number of Single Family 60 Corner Lots = 55 lots
Assumed Impervious Area Per Single Family 60 Comer Lot = 4 000 square feet
Total Impervious Area from Single Family 60 Corner Lots = 22 000 square feet
0 51 acres
Total Open Space Lots = 2 lots
Assumed Impervious Area Per Open Space Lot = 5 000 square feet
Total Impervious Area from Open Space Lots = 10 000 square feet
0 23 acres
Total Sidewalk Impervious Area = 32 704 square feet
0 75 acres
Total Roadway Impervious Area = 123 537 square feet
284 acres

BRIAR CHAPEL PHASE 6 NORTH HYDROLOGIC CALCULATIONS
NEW 12000 Post Development To Wet Pond
J FINCH PE
6/14/2012
Contributing Area
SCS CN
Area [acres]
Comments
On site open
61
984
Assume good condition
On site impervious
98
1026
On site wooded
55
000
Assume good condition
On site pond
100
059
Off site open
61
000
Assume good condition
Off site impervious
98
000
Off site wooded
55
000
Assume good condition
Off site pond
100
000
Total area =
Composite SCS CN =
/o Impervious =
2069 acres
00323 sq mi
80
496%
B Time of Concentration Information
Due to the amount of piped and overland pavement,Jlow the post development time of concentration was assumed to be S minute
Time of Concentration = 500 minutes
SCS Lag Time = 300 minutes (SCS Lag = 0 6* Tc)
=
00500 hours
__ Time Increment = 087 minutes (= 0 29 *SCS Lag)

[jEcoEngineering
A di o f Th J h R. M Adan C mpany !
Scenario Post
Wet Pond Out
SWMF FinalDesign ppc Page 1 of 1
SWMF FinalDesign ppc 6/14/2012

F4-]EcoEngineering
A drvi on f Th J hn R M Adam Company Inc
Subsection Master Network Summary
Catchments Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
( vears) (ft3)
TO WET POND
Post 1
1
90 942 000
722 000
4346
TO WET POND
Post 2
2
126 338 000
721000
6048
TO WET POND
Post 10
10
227 527 000
721 000
9667
TO WET POND
Post 25
25
290 462 000
721 000
11439
TO WET POND
Post 100
100
395 443 000
L 721000,
13831
Node Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
( vears) (ft3)
Wet Pond Out
Post 1
1
14 621000
1440 000
036
Wet Pond Out
Post 2
2
45 610 000
901 000
220
Wet Pond Out
Post 10
10
146 061000
751 000
2441
Wet Pond Out
Post 25
25
208 656 000
729 000
5033
Wet Pond Out
Post 100
100
313 207 000
728000,
7098,
Pond Summary
Label Scenario Return Hydrograph Time to Peak Peak Flow
Event Volume (min) (ft3 /s)
(years) (ft3)
Maximum Maximum
Water Pond Storage
Surface (ft3)
Elevation
M
WET POND
(IN)
Post 1
1
90 942 000
722 000
4346
(N /A)
(N /A)
WET POND
(OUT)
Post 1
1
14 621 000
1440 000
036
47439
76 322 000
WET POND
(IN)
Post 2
2
126 338 000
721 000
6048
(N /A)
(N /A)
WET POND
(ate
Post 2
2
45 610 000
901 000
220
47460
83 510 000
WET POND
(IN)
Post 10
10
227 527 000
721 000
96 67
(N /A)
(N /A)
WET POND
(ate
Post 10
10
146 061000
751 000
2441
47504
99 361000
WET POND
(IN)
Post 25
25
290 462 000
721 000
11439
(N /A)
(N /A)
WET POND
(OUT)
Post 25
25
208 656 000
729 000
5033
47538
111 706 000
WET POND
(IN)
Post 100
100
395 443 000
721 000
13831
(N /A)
(N /A)
WET POND
(OUT)
Post 100
100
313 207 000
728 000
7098
47594
131 884 000
SWMF FinalDesign ppc Page 1 of 1
SWMF FinalDesign ppc 6/14/2012

WET POND FINAL DESIGN CAL CULA TIONS
BRIAR CHAPEL - PHASE 6 NORTH
NEW 12000

BRIAR CHAPEL PHASE 6 NORTH WET POND J FINCH PE
NEW 12000 5/10/2012
Stage - Storage Function
Project Name
Briar Chapel Phase 6 North
Designer
J Finch PE
Job Number
NEW 12000
Date
5/10/2012
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Volume
Contour Stage Area Area Volume Volume w/ S S Fxn
(feet) (feet) (SF) (SF) (CF) (CF) (CF)
47200
1 00
1 25869
47250
-4_73
05
MI
29 691
_
27780 L 1 13890 wow 13890 _
-"--09-9
—1152-0o­+
051 TM
00
0 a
31,131
30411 Y 290396_
_ M
474 00
1 2 0
33 737
32434 32434 ' 61529
1W
- - --�—� -
3 0
_.__..
4 0
_-�
475 00
.,.__.__-v._
476
_T6 -2
36 442
_ _. _ --37-84-47-1
- ,
I 35089 ( 35089 �j -9C6 19 _
-1-3446-2
�
� —2 97
_
^4
00
477 00
�v
5 0
39 246
i2-150
37844 134462
—4069-8---T— 40698 175160
O1
31-0
Storage vs Stage
200000
180000
160000
y= 29293x , 0979
140000 RZ = 0 9997
v 120000
00100000
$ 80000
60000
40000
20000 - ,,o0000000000000000000
0
00 10 20 Stags Beet) 40 50 60
Ks = 29293
b = 10979

BRIAR CHAPEL PHASE 6 NORTH WET POND
NEW 12000
_> Stage
Storage Function
Ks =
29293
b =
10979
Zo =
47200
Elevation ! Storage
[feet] i [cf] [acre -feet]
47200 0
0 000
47220 5005
0 115
47240 10712
0 246
_472 60 F 16718
4
0 384
472 80 a 22928
0 526
473 00 y 9
47320 35785
47340 4 42384
0 672
0 822
0 973
_ 4_73 60
49076 1 127
38
S851 ; 1 282
47400
62700
1 439
474 20
E 69616
1 598 1
7440
76595
-T-75-8-1
�
—
474 60
83630
j 1 920
_474 80W
90719
E
2 083
47500
97858
2 247
47520
105043
2 411
47540
112273
119544
2 577
274-4
47560
475 80
126855
2 912
47600
134204
3 081
476 20
1415_89
3 250
476-46—
149008
3 421
47660
156461
3 592
476 80
163945
3 764 l
47700
171460
3 936
J FINCH PE
5/10/2012

[4ECoEngineering
Ad j fT4 Min n1 Adim C mo, v I
Subsection Outlet Input Data
Label Wet Pond
Requested Pond Water Surface Elevations
Minimum (Headwater) 472 00 ft
Increment (Headwater) 0 10 ft
Maximum (Headwater) 477 00 ft
Outlet Connectivity
Structure Type Outlet ID Direction Outfall E1 E2
(ft) (ft)
Inlet Box
Puser 1
Forward
Culvert 1
47450
47700
Onfice Circular
Orifice 1
Forward
Culvert 1
47200
47700
Culvert - Circular
Culvert 1
Forward
TW
46600
47700
Tallwater Settings
Tallwater
(N /A)
(N /A)
SWMF FinalDesign ppc Page 1 of 4
SWMF FinalDestgn ppc 5/11/2012

AEcoEngneenng
d swn fT&Jh RMAd n C p !
Subsection Outlet Input Data
Label Wet Pond
Structure ID Riser 1
Structure Type Inlet Box
Number of Openings
1
Elevation
474 50 ft
Orifice Area
25 0 ftZ
Orifice Coefficient
0 600
Weir Length
20 00 ft
Weir Coefficient
3 00 (ft-0 5) /s
K Reverse
1000
Manning s n
0 000
Kev Charged Riser
0 000
Weir Submergence
False
Orifice H to crest
False
SWMF FinalDesign ppc Page 2 of 4
SWMF FinalDesign ppc 5/11/2012

F4EcoEngineering
A da y n M 1 t R AdcAA C p n 1
Subsection Outlet Input Data
Label Wet Pond
Structure ID Culvert 1
Structure Type Culvert Circular
Number of Barrels
1
Diameter
30 0 in
Length
83 00 ft
Length (Computed Barrel)
83 10 ft
Slope (Computed)
0 048 ft/ft
Outlet Control Data
Manning s n
0 013
Ke
0 500
Kb
0 009
Kr
0 000
Convergence Tolerance
0 00 ft
Inlet Control Data
Equation Form
Form 1
K
00098
M
20000
C
00398
Y
06700
TI ratio (HW /D)
0 000
T2 ratio (HW /D)
1 283
Slope Correction Factor
-0S00
Use unsubmerged inlet control 0 equation below T1
elevation
Use submerged inlet control 0 equation above T2
elevation
In transition zone between unsubmerged and submerged
inlet control
interpolate between flows at T1 & T2
TI Elevation 466 00 ft Tl Flow
27 16 ft3 /s
T2 Elevation 469 21 ft T2 How
3105 ft3 /s
SWMF -Fins lDeslgn ppc Page 3 of 4
SWMF- FinalDesign ppc 5/11/2012

[4EcoEngineenng
Adiv nn ofTh i I n R A4 Ad s mpany Inc
Subsection Outlet Input Data
Label Wet Pond
Structure ID Onfice 1
Structure Type Onfice Circular
Tallwater Type
Number of Openings
1
Elevation
472 00 ft
Orifice Diameter
3 0 In
Orifice Coefficient
0 600
0 01 ft
(Minimum)
Structure ID TW
Structure Type TW Setup DS Channel
Tallwater Type
Free Outfall
Convergence Tolerances
Maximum Iterations
30
Tailwater Tolerance
0 01 ft
(Minimum)
Tallwater Tolerance
0 50 ft
(Maximum)
Headwater Tolerance
0 01 ft
(Minimum)
Headwater Tolerance
0 50 ft
(Maximum)
Flow Tolerance (Minimum)
0 001 ft3 /s
Flow Tolerance (Maximum)
10 000 ft3 /s
SWMF FinalDeslgn ppc Page 4 of 4
SWMF FInalDeslgn ppc 5/11/2012

[aEcoEngineenng
4191 3 1 f Th J 1 R M Ad m ('o p y l
Subsection Composite Rating Curve
Label Wet Pond
Composite Outflow Summary
Water Surface Flow Tallwater Elevation Convergence Error
Elevation (ft3 /s) (ft) (ft)
(ft)
47200
000
(N /A)
000
47210
002
(N /A)
000
47220
006
(N /A)
000
47230
010
(N /A)
000
47240
012
(N /A)
000
47250
014
(N /A)
000
47260
016
(N /A)
000
47270
018
(N /A)
000
47280
019
(N /A)
000
47290
021
(N /A)
000
47300
022
(N /A)
000
47310
023
(N /A)
000
47320
025
(N /A)
000
47330
026
(N /A)
000
47340
027
(N /A)
000
47350
028
(N /A)
000
47360
029
(N /A)
000
47370
030
(N /A)
000
47380
030
(N /A)
000
47390
031
(N /A)
000
47400
032
(N /A)
000
47410
033
(N /A)
000
47420
034
(N /A)
000
47430
035
(N /A)
000
47440
036
(N /A)
000
47450
037
(N /A)
000
47460
227
(N /A)
000
47470
574
(N /A)
000
47480
102S
(N /A)
000
47490
1557
(N /A)
000
47500
2162
(N /A)
000
47510
2829
(N /A)
000
47520
3555
(N /A)
000
47530
4336
(N /A)
000
47540
S163
(N /A)
000
47550
6031
(N /A)
000
47560
6926
(N /A)
000
47570
6996
(N /A)
000
47580
7039
(N /A)
000
47590
7082
(N /A)
000
47600
7125
(N /A)
000
SWMF- FinalDeslgn ppc Page 1 of 3
SWMF F1nalDeslgn ppc 5/11/2012

[4EcoEngineenng
Ad m of TI J hn R. McAd m f Mt a Y I
Subsection Composite Rating Curve
Label Wet Pond
Composite Outflow Summary
Water Surface How
Elevation W /s)
(ft)
47610
47620
47630
47640
47650
47660
47670
47680
47690
477001
7167
7210
7252
7293
7334
7375
7417
7457
7498
75381
Tailwater Elevation
(ft)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A)
(N /A) 1
Convergence Error
(ft)
000
000
000
000
000
000
000
000
000
000
Contributing Structures
(no Q Riser i Orifice 1 Culvert 1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert i (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert i (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
i Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Orifice
1 Culvert 1 (no Q Riser
1)
Onfice
1 Culvert 1 (no Q Riser
1)
Riser
1 Orifice 1 Culvert 1
Riser
1 Orifice 1 Culvert 1
Riser
1 Orifice 1 Culvert 1
Riser
1 Orifice 1 Culvert 1
SWMF FInalDeslgn ppc Page 2 of 3
SWMF FinalDeslgn ppc 5/11/2012

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND
NEW 12000 Above NWSE
(FSTAGE STORAGE FUNCTION ABOVE NORMAL POOL 7 —�
Average
Incremental
Accumulated
Estimated
Contour Contour
Contour
Contour
Stage
Contour Stage Area Area
Volume
Volume
w/ S S Fxn
(feet) (feet) (SF) (SF)
(CF)
(CF1
(feetl
47200
000
25 869
47250
050
29 691
27780
13890
13890
051
47300
100
31 131
30411
15206
29096
099
47400
200
33 737
32434
32434
61529
197
47500
300
36 442
35089
35089
96619
297
47600
400
39 246
37844
37844
134462
401
47700
500
42 150
40698
40698
175160
510
Ks = 29293
b = 1097
J FINCH PE
6/14/2012

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND
NEW 12000 Below NWSE Main Pool
��SfA STORAGE FUNCTION MAIN
Ks = 10313
b = 11011
J FINCH PE
6/14/2012
Storage vs Stage
80000 —
Average
Incremental
Accumulated
Estimated
R = 0 9995
60000
Contour
Contour
Contour
Contour
Stage
Contour
Stage
Area
Area
Volume
Volume
w/ S S Fxn
(feet)
(feet)
(SF)
(SF)
(CF)
(CF)
(feet)
46600
000
10 127
46700
100
10 897
10512
10512
10512
102
46800
200
11 692
11294
11294
21806
197
46900
300
12 512
12102
12102
33907
2 95
47000
400
13 357
12934
12934
46842
395
47100
500
14 227
13792
13792
60633
500
47150
550
14 672
14449
7225
67858
553
47200
600
17 128
15900
7950
75808
6 12
Ks = 10313
b = 11011
J FINCH PE
6/14/2012
Storage vs Stage
80000 —
70000
y = 10313x' 01
R = 0 9995
60000
V 50000
40000
0
N 30000
20000
10000
0
000
100 200 300 400 500 600 700
Stage (feet)
Ks = 10313
b = 11011
J FINCH PE
6/14/2012

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND
NEW 12000 Below NWSE Forebay #1
STAGE STORAGE FUNCTION RO—RTH F A7Y
Contour
(feet)
46600
Stage
(feet)
000
Contour
Area
(SF)
744
Average
Contour
Area
(SF)
Incremental
Contour
Volume
(CF)
Accumulated
Contour
Volume
(CF)
Estimated
Stage
w/ S S Fxn
(feet)
46700
46800
46900
47000
47100
47150
47200
100
963
853
853
853
105
200
1 320
1142
1142
1995
191
300
1724
1522
1522
3517
285
400
2 174
1949
1949
5466
388
500
2 615
2395
2395
7861
501
550
2 821
2718
1359
9220
560
600
4 156
3488
1744
10964
633
Ks = 79132
b = 14250
J FINCH PE
6/14/2012
12000
Storage vs Stage
s
10000--
y = 791 32X1425
R2 = 0 9954
C
8000
v
6000
y
4000
2000
0
000
1 00 200 300 400 500 600 700
Stage (feet)
Ks = 79132
b = 14250
J FINCH PE
6/14/2012

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND
NEW 12000 Below NWSE Forebay #2
FSTAGE STORAGE FUNCTION NORTH FOREBAY
L— Ks = 11049
b = 13463
J FINCH PE
6/14/2012
Average
Incremental
Accumulated
Estimated
Contour
Contour
Contour
Contour
Stage
Contour
Stage
Area
Area
Volume
Volume
w/ S S Fxn
(feet)
(feet)
(SF)
(SF)
(CF)
(CF)
(feet)
460 00
000
1009
46100
100
1333
1171
1171
1171
104
46200
200
1693
1513
1513
2684
193
46300
300
2090
1891
1891
4575
287
46400
400
2 524
2307
2307
6882
389
46500
500
2 994
2759
2759
9641
500
46550
5 50
3207
3100
1550
11191
558
46600
600
4 586
3896
1948
13139
629
L— Ks = 11049
b = 13463
J FINCH PE
6/14/2012

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND
NEW 12000 Summary
I TOTAL VOLUME OF fACII/TY- �, � � �- �-
Volume of Main Pool =
75 808
cf
Volume of Forebay #1 =
10 964
cf
Volume of Forebay #2 =
13 139
cf
Total Volume Below NWSE =
99 911
cf
=
229
acre ft
Total Volume Above NWSE = 175 160 cf
402 acre ft
Total Volume of Facility = 275 071 cf
631 acre ft
Il FOREBAY PERCENTAGE OF
ER. NENT POMOLUME
Per NCDWQ design guidelines the forebay volume should equal approximately
20Y of the total permanent pool volume
Total Volume Below NWSE = 99 911 cf
Volume of Forebay #1= 1
10 964 cf
Volume of Forebay #2 = 1
13 139 cf
Total Volume of Forebays = 2
24 103 cf
V Forebay = 2
24 19'
)TZ,79
Total Volume Below NWSE = 99 911 cf
Surface Area at NWSE = 25 869 sf
Average Depth = 386 ft
J FINCH PE
6/14/2012

NCDENR Stormwater BMP Manual Chapter Revised 06 16 09
Table 10 -3
Surface Area to Drainage Area Ratio for Permanent Pool Sizing to Achieve 0 Percent TSS
Pollutant Removal Efficiency in the Mountain an redmon Regions Adapted from Driscoll 1986
Percent
Impervious
Cover
30
35
40
Permanent Pool Average Depth (ft)
45 50 55 60 65 70
75
80
85
90
10%
09
08
08
07
06
06
05
05
05
05
04
04
04
20%
15
13
11
10
10
09
09
09
08
08
08
07
07
30/
19
18 17
15
14
14
13
11
10
10
10
09
09
40%
25
23
20
19
18
17
16
16
15
14
13
12
11
50/
30
28
25
23
20
19
19
18
17
16
16
15
15
60%
35
32
28
27
25
24
22
21
19
19
18
18
17
70%
40
37
33
31
28
27
25
24
22
21
20
20
19
80%
45
41
38
35
33
30
28
27
26
24
23
21
20
90% 1
50
45
40
38
35
33
30
29
28
27
26
25
24
Table 10-4
Surface Area to Drainage Area Ratio for Permanent Pool Sizing to Achieve 90 Percent TSS
Pollutant Removal Efficiencv in the Coastal Reown Arlanterl from Drmrnll 1 Qszti
Percent
Impervious
Cover
30
35
40
Permanent Pool Average Depth (ft)
45 50 55 60
V
65
70
75
10%
13
10
08
07
06
05
04
03
02
01
20%
24
20
18
17
15
14
12
10
09
06
30%
35
30
27
25
22
19
16
13
11
08
40%
45
40
35
31
28
25
21
18
14
11
50/
56
50
43
39
35
31
27
23
19
15
60%
70
60
53
48
43
39
34
29
24
19
70%
81
70
60
55
50
45
39
34
29
23
801
94
80
70
64
57
52
46
40
34
28
90%
107
90
79
72
65
59
52
46
39
33
100%
12
100
88
81
73
66
58
51
43
36
The engineering design of a wet detention basin must include a 10 foot wide (minimum)
vegetated shelf around the full perimeter of the basin The inside edge of the shelf shall
be no deeper than 6 below the permanent pool level and the outside edge shall be 6
above the permanent pool level For a 10 wide shelf the resulting slope is 101 With
half the required shelf below the water (maximum depth of 6 inches) and half the
required shelf above the water the vegetated shelf will provide a location for a diverse
population of emergent wetland vegetation that enhances biological pollutant removal
provides a habitat for wildlife protects the shoreline from erosion and improves
sediment trap efficiency A 10 wide shelf also provides a safety feature prior to the
deeper permanent pool
Short circuitmg of the stormwater must be prevented The most direct way of
minimizing short circuiting is to maximize the length of the flow path between the mlet
and the outlet basms with long and narrow shapes can maximize the length of the flow
path Long and narrow but irregularly shaped wet detention basms may appear more
Wet Detention Basin 1015 July 2007

BRIAR CHAPEL PHASE 6 NORTH WET DETENTION POND J FINCH PE
NEW 12000 Surface Area Calculation 6/14/2012
ET DETENTION BASIN SUMMARY
From Stormwater Best Management Practices Manual NCDENR Division of Water Quality October 2007
Enter the drainage area characteristics = =>
Total drainage area to pond = 2069 acres
Total impervious area to pond = 1026 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond notjust the impervious
surface from on site development
Drainage area = 2069 acres @ 496% impervious
Estimate the surface area required at pond normal pool elevation = =>
Wet Detention Basins are based on an minimum average depth of = 386 feet (Calculated)
From the DWQ BMP Handbook (1012007) the required SA /DA ratio for 90% TSS Removal = =>
35
386
40
Lower Boundary => 400 23
20
Site Y impervious => 496 278
256
25
Upper Boundary => Soo 28
25
Therefore SA /DA required =
256
Surface area required at normal pool =
23 085
ft 2
=
053
acres
Surface area provided at normal pool =
25 869
ft 2

BRIAR CHAPEL PHASE 6 NORTH WATER QUALITY VOLUME
NEW 12000 CALCULATIONS
> Determination of Water Quality Volume (1 Rainfall Depth]
Proposed Conditions =>
WQ v = (P)(R v)(A) 112
where
WQv = water quality volume (in acre ft)
Rv = 0 05 +0 009(I) where I is percent impervious cover
A = area in acres
P = rainfall (in inches)
Input data
Total area A =
2069
acres
=
901 122
sf
Impervious area =
1026
acres
=
446 791
sf
Percent impervious cover I =
496
%
Rainfall P =
10
inches
Calculated values
RV = 050
WQv = 0 855 acre ft
37 264 cf
> Associated Depth above Wet Pond Permanent Pool
Ks=
29293
b =
10979
V =
37264
Normal Pool Elevation =
47200 feet
Riser Crest Elevation =
47450 feet
WQ Elevation = 47325 feet
J FINCH PE
6/14/2012

BRIAR CHAPEL PHASE 6 NORTH
NEW 12000
Inverted Siphon Design Sheet
D orifice
# orifices
Ks
b
Cd siphon
Normal Pool Elevation
Volume @ Normal Pool
Orifice Invert
WSEL @I Runoff Volume
3 inch
1
29293
10979
060
47300 feet
0 cf
47300 feet
47425 feet
WSEL
feet
Vol Stored
(c f)
Siphon Flow
(cfs )
Avg Flow
(cfs )
Incr Vol
(c )
Incr Time
(sec)
47425
37264
0 250
47414
33691
0 237
0 244
3573
14673
47403
30152
0 224
0 231
3539
15344
47392
26649
0 210
0 217
3503
16136
47381
23187
0 195
0203
3462
17092
47370
19770
0 179
0 187
3416
18278
47359
16406
0 161
0 170
3364
19810
47348
13102
0 141
0 151
3304
21908
47337
9872
0 117
0 129
3230
25057
47326
6735
0 087
0 102
3137
30683
473 15
37264
0 040
0 064
3008
47222
Drawdown Tune = 2 62 days
By comparison if calculated by the average head over the orifice (assuming
average head is one third the total depth) the result would be
Average driving head on orifice = 0 373 feet
Orifice composite loss coefficient = 0 600
Cross sectional area of 3 orifice = 0 049 sf
Q = 0 1444 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec /day)
Drawdown Time = 2 99 days
Conclusion Use 1 3 Diameter Inverted Siphon to drawdown the accumulated
volume from the 10 storm runoff with a required time of about 2 62 days
J FINCH PE
6/14/2012

J
BRIAR CHAPEL
NEW 12000
Input Data =>
Square Riser/Barrel Anti- Flotation Calculation Sheet
Inside length of riser =
500 feet
Inside width of riser =
500 feet
Wall thickness of riser =
600 inches
Base thickness of riser =
800 inches
Base length of riser =
600 feet
Base width of riser =
600 feet
Inside height of Riser =
850 feet
Concrete unit weight =
142 0 PCF
OD of barrel exiting manhole =
4400 inches
Size of dram pipe (if present) =
80 inches
Trash Rack water displacement =
6174 CF
Concrete Present in Riser Structure =>
Total amount of concrete
Adjust for openings
Base of Riser = 24 000 CF
Riser Walls = 93 500 CF
Opening for barrel = 5 280 CF
Opening for dram pipe = 0 175 CF
J FINCH PE
5/10/2012
Note NC Products lists unit wt of
manhole concrete at 142 PCF
Total Concrete present adjusted for openings = 112 046 CF
Weight of concrete present = 15911 lbs
Amount of water displaced by Riser Structure =>
Displacement by concrete =
112 046 CF
Displacement by open air in riser =
212 500 CF
Displacement by trash rack =
61 740 CF
Total water displaced by riser/barrel structure = 386 286 CF
Weight of water displaced = 24104 lbs
Calculate amount of concrete to be added to riser =>
Safety factor to use = 125 (recommend 125 or higher)
Must add = 14220 lbs concrete for buoyancy
Concrete unit weight for use = 142 PCF (note above observation for NCP concrete)
Buoyant weight of this concrete = 7960 PCF
Buoyant with safety factor applied = 6368 PCF
Therefore must add = 223 301 CF of concrete
Standard based described above = 24 000 CF of concrete
Therefore base design must have = 247 301 CF of concrete

BRIAR CHAPEL
NEW 12000
Calculate size of base for riser assembly =>
Length = 9 000 feet
Width = 9 000 feet
Thickness = 37 0 inches
Concrete Present = 249 750 CF OK
Check vandcty of base as designed =>
Total Water Displaced = 612 036 CF
Total Concrete Present = 337 796 CF
Total Water Displaced = 38191 lbs
Total Concrete Present = 47967 lbs
Actual safety factor = 126 OK
Results of design =>
Base length =
9 00 feet
Base width =
9 00 feet
Base Thickness =
37 00 inches
CY of concrete total in base =
9 25 CY
Concrete unit weight in added base >=
142 PCF
J FINCH PE
5/10/2012

Briar Chapel — Phase 6 North
Project # NEW -12000
VELOCITY DISSIPATOR DESIGN
Designed By J Finch, PE
Velocity Dissipator — Proposed Wet Pond
NRCD Land Quality Section
Pipe Design
Entering the following values will provide you with
the expected outlet velocity and depth of flow in a
pipe assuming the Mammngs roughness number is
constant over the entire length of the pipe
flow Q in cfs 25 Flow depth (ft) = 0 90
slope S in % 4 82 Outlet velocity (fps) = 15 698
pipe diameter D in in 30
Manning number n 0 013
NRCD Land Quality Section
NYDOT Dissipator Design Results
Pipe diameter (ft)
250
Outlet velocity (fps)
1570
Apron length (ft)
2000
AVG DIAM STONE
THICKNESS
(inches) CLASS
(inches)
3 A
9
6 B
22
» 13 Bor1
22«
23 2
27
Width Calculation
WIDTH = La + Do
WIDTH =20 +25
WIDTH = 23 FEET
CONCLUSION
Use NCDOT Class `1' Rip Rap
20'L x 23'W x 22 "Thick