SW6111005_COMPLIANCE_20120117

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO,
SW
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
U51COMPLIANCE EVALUATION INSPECTION
DOC DATE
d� /2 Z%%
YYYYM M D D

Lawyer, Mike
From:
Lawyer, Mike
Sent:
Tuesday, January 17, 2012 12:59 PM
To:
'Benjamin Lennon'; 'Lou Sadler'
Cc:
'Brent Lockamy'
Subject:
Tyler's Ridge
Gentlemen,
My apologies for not sending this out last week like I said I would. I came down with a bad cold and was out of work
Wednesday through Friday, plus we were closed yesterday for MLK Day. Anyway, here's the list of comments/additional
information needed as discussed during our meeting last week.
-need landscape plans for the bio-retention areas
-need soil evaluation information for each bio-retention area
-need additional information for drainage area 4 to account for single-family lots (drainage area and proposed BUA)
-applicable drainage areas and bio-retention areas may need to be modified to account for increase in cul-de-sacs per
Town requirements
-bio-retention area #3 to be eliminated as a designed/approved basin
-bio-retention area #5 to be moved slightly to account for Town's landscape buffer and resized to account for both
roadway improvements (Hwy 22)
If you need any clarification on the above items or have additional questions, please contact me. Please provide the
requested information on or before February 29, 2012 to avoid having the application returned, which would require re -
submittal with associated review fee.
Thanks,
Mike
Michael Lawyer, CPSWQ
Environmental Specialist
NCDENR-Division of Water Quality
Surface Water Protection Section
Fayetteville Regional Office
Direct: [phone]
Main: [phone]
Fax: [phone]
e-mail: [e-mail]
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed
to third parties unless the content is exempt by statute or other regulation.

NIICI IAEI, A. NFAI. s ASSOCbYtts, PI.I.0
I.E ERS,SURVl:MRS.AND hl.,t.NERS
105 \Yell Corbin Street, Suite 201
Ilillsburough, North Carolina 27278
[phone] nmeal-manaru�manarnginarzcnm
December 8. 2011
Michael Lawyer
Environmental Specialist
NCDL'NR-Division of Water Quality
Surface Water Protection Section
Fayetteville Regional Office
Re: Tyler's Ridge at Sandhills
Mr. Lawyer,
DENR-FRO
GZ.0 14 2011
DWQ
Below are responses (in red) to your preliminary review of Tyler's Ridge at Sandhills D WQ permit
application.
I. As an FYI, item 1112 and item IX on the main application form did not need to be completed per the
instructions of item III Ic. This does not need to be corrected, but considered for future reference.
Response: Do nothing
2. The project area shown under item IV7 is 33.08 acres and with the proposed density of23.2% calculates
334.304sf of BUA, however the attached table adds up to a total of 323,779sf and the narrative and Deed
Restrictions show a maximum BUA of 338,897sf. The amount of 13UA needs to be consistent throughout
the application package.
Response: A revised form and Basin Information Table is included showing the correct areas and numbers.
3. The attached table of drainage areas and proposed BUA does not include the BUA breakdown for
buildings, roads, etc. as would he indicated in the table in the application.
Response: Revised Basin Information Table included.
4. The attached table only shows a total drainage area of 689,080sf, which does not account for the entire
project area of 1,440,965sf (33.08acres x 43,560sf/ac). You must account for the drainage of the entire
project area.
Response: Basin Information Table included has been revised to show the correct project area: Project
Area (onsite drainage area) = 1,459,535 SF or 33.51 AC. This excludes water of the US.
5. The topographic map shows open waters and the site plans show a 30' perennial stream setback. You
must exclude the surface area of any water bodies from the project area. If this has been done please
indicate so, otherwise you must calculate those surface areas and show their exclusion front the project
area. The surface area of non -coastal wetlands can still be included.
Response: Waters of the US excluded. Forth is revised to show this.
6. Regarding the bio-retention supplement forms, pre/post calculations are not required under the 1IQW
program. I believe this is required by the Town of Southern Pines, but does not need to be shown on the
state forms. As already noted on the supplement forms, you must bypass stonnwater flow in excess of the

design volume and provide a vegetated filter for the excess Flow. In addition, you need to provide the inlet
velocity or show the use of energy dissipating devices and the values for the separation of I WS and surface
for cells 3 8 4.
Response: The basins are all designed as "on-line". Each basin has one or two outlets — either a drop inlet
and emergency overflow weir in the berm orjust a weir in the berm. Each bioretention basin is designed to
hold 12" of water before discharging runoff. Therefore, the basins capture and treat varied amounts of
runoff before it is bypassed, and each basin treats significantly more runoff than the design volume.
Attached are rip rap apron calculations.
7. The narrative states that a portion of the entrance drive (Fen Court) runoff cannot be treated due to
grades and space limitations. All runoff from areas within the project area must be treated.
Response: An additional Bioretention basin is proposed (BMP 95) to treat this runoff.
8. Plan sheet C-5 shows an area to the northwest with a drainage Swale and pipe that does not enter the bio-
retention basin #4. Please explain. Again, all runoff must be accounted for and treated.
Response: Swale 5 and Swale behind the future apartment building capture offsite and non-BUA runoff,
therefore by-pass the basin and does not need to be treated.
Please let me know if you have any questions or need additional information
Sincerely, X,i,-
k
Begjanun R. Lennon. PF
Micheal A. Ncal X Associates
105 West Corbin Street, Suite 201
Hillsborough, NC 27278
(919)-644-1277
[e-mail]

AA AA A
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STORMWATER OVERVIEW
DESCRIPTION OF EXISTING SITE
Tyler's Ridge at Sandhills is a residential project located on 33 acres in Moore County within the
Town of Southern Pines planningjurisdiction. Specifically the project is located on the west side
of HWY 22 just south of the Moore County Regional Airport. The site is zoned PD-PRD,
planned development -planned residential development. The existing site's elevations range from
445 feet to 390 feet, with slopes ranging from 20% in isolated areas to very flat. There are
approximately 2.56 acres wetlands in the lower portions of the site. "Three types of soils exist on
the property according to the USDA soil Survey: CaB — Candor sand, 0 to 4% slopes, CaC —
Candor sand, 4 to 12% slopes, and AeD — Ailey loamy sand, 8 to 15% slopes. CaB and CaC are
in the "A" hydrologic soils group, and AeD is in the "B" hydrologic soils group. The higher
elevations on the site are sparsely wooded with pines, while the lower elevations and wetlands
are more dennsly wooded. Tile majority of the site drains to the wetlands, which outlets through
a 48" CMP under highway 22 on the southeast end of the site.
DESCRIPTION OF PROPOSED SITE
The project's Development Plan consists of 144 one and two bedroom apartment units (in 6
separate buildings) with accompanying club house, pools, leasing office, and garages. Future
development of 3 more apartment buildings and additional parking is shown on the plans, it is
unknown when this development will take place. Stormwater management has been designed
for the total build -out of the project. Five bioretention basins are proposed to capture runoff
from the proposed development.
IMPERVIOUS SURFACE
This project is located in a Class-111 High Quality watershed and is regulated by 15A NCAC
02B .0215. There are several development options for nonpoint source and stormwater pollution
control. From the Town of Southern Pines regulatory standpoint, the development is considered
"low density". The criteria consists of: Development density must be limited to either no more
than two dwelling units of single family detached residential development per acre (or 20,000
square foot lot excluding roadway right-of-way) or 24 percent built -upon area for all other
residential and non-residential development in watershed outside of the critical area; Stormwater
runoff from the development shall be transported by vegetated conveyances to the maximum
extent practicable. However, lorm a DWQ regulatory standpoint, the development is greater
than 12% 13UA and is considered high density.
The site is outside of the critical area, therefore this portion of the project will be less than 24%
built upon (impervious) area. The proposed impervious area for the entire project (future
buildings included) is 326,036 s.f. or 22.701/0 of the total project area.

STORMWATER MANAGEMENT
Runoff from the proposed development will be conveyed by sheet flow, pipes, and grass swales
to one of five bioretention basins. All runoff from the proposed new impervious surface will be
captured and treated by one the basins.
CALCULATIONS
The bioretention basins were designed according to methods in the NCDERN BMP Manual.
Sizing workseets are provided for each basin. Additionally, the basins were modeled using
HydroCAD. These calculations are also included. Storm pipes were modeled using HydrFlow,
and these calculations are also included.
WATER QUALITY
Each BMP utilized in this project is designed according to the specifications and practices in the
NCDENR BMP manual. Bioretention basins remove 85% of total suspended solids, 35% of
total nitrogen, and 45% of total phosphorus. In addition to water quality benefits, bioretetion
basins provide a natural integration between urban landscapes and the natural landscape, adding
addition value to the land.
SEDIMENT AND EROSION CONTROL
The land disturbance associated with this project will require approval of a sedimentation and
erosion control plan by the Town of Southern Pines. Land disturbance is approximately 18
acres, and a plan and permit application has been submitted to the Town for approval.

Phone: ( ) Fax
Email:
4. Local jurisdiction for building permits:
Point of Contact: Phone #:
IV. PROJECT INFORMATION
1. In the space provided below, briefly summarize how the stormwater runoff will be treated.
Stormwater will be treated with bioretention basins.
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:
❑ Valid 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 drains to the Cape Fear River basin.
4. Total Property Area: 34.43 acres
5. Total Coastal Wetlands Area: 0 acres
6. Total Surface Water Area: 0.92 acres
7. Total Property Area (4) -Total Coastal Wetlands Area (5) - Total Surface Water Area (6) = Total Project
Area':33.51 acres
Total project area shall be calculated to exclude the followiug the normal pool of impounded structures, the area
between the banks of streams and rivers, the area below the Norrual 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 (BUA). 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 = 22.70
9. How many drainage areas does the project have?5 (For high density, count 1 for each proposed engineered
stornmoater 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.
Form SWU-101 Version 07Jun2010 Page 3 of 7

Bioretention Basin Bioretention Basin Bioretention Basin Bioretention Basin
#1 #2 #3 #4
Basin Information
Drainage Area 1 ,
Drainage Area 2 .
Drainage Area 3
Drainage Area 4
Receiving Stream Name
Mill Creek
Mill Creek
Mill Creek
Mill Creek
Stream Class
WSIII; HQW:@
WSIII; HOW:
WSIII; HQW:@
WSIII; HQW:
Stream Index Number
18-23-11- 1
18-23-11-(1)
18-23-11- 1
18-23-11- 1
Total Drainage Area sf
299,516
167,565
109,089
112,910
On -Site Drainage Area (sfi
299,515
167,565
109,089
112,910
Off -site Drainage Area (sf)
0
0
0
0
Proposed ImerviousArea sf
166,146
66,169
40,687
50,777
% Impervious Area total
55.47%
39.49°/'
37.30%
44.97%

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Lawyer, Mike
From:
Lawyer, Mike
Sent:
Tuesday, November 29, 2011 9:55 AM
To:
'Benjamin Lennon'
Cc:
Michael Neal
Subject:
RE: Tylers Ridge
After further review of the BMP Manual, a vegetative filter strip is only required for projects draining to SA waters,
which Tylers Ridge is not. Therefore, an overflow device without a filter strip is OK. Apparently the supplement form
needs to be revised so that that error message does not show up for projects outside the coast. My mistake and my
apologies for that specific comment. I also see that the proposed bio-retention areas do not include underdrains or IWS,
so obviously you don't have to provide the separation of IWS and Surface value as noted in my comment 6.
Regarding the rest of comment 6, you do need to show that volume in excess of the design volume will bypass the cell.
The supplement forms for cells 2, 3 & 4 should be revised to reflect this. The inlet velocities or use of energy dissipating
devices for each cell also still needs to be addressed along with the other comments provided previously.
Again, my apologies regarding the filter strip and IWS values. Please disregard those comments.
Thanks,
Mike
Michael Lawyer, CPSWQ
Environmental Specialist
NCDENR-Division of Water Quality
Surface Water Protection Section
Fayetteville Regional Office
Direct: [phone]
Main: [phone]
Fax: [phone]
e-mail: [e-mail]
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed
to third parties unless the content is exempt by statute or other regulation.
From: Benjamin Lennon rmaiIto: blennon(d)manaenoineers.coml
Sent: Monday, November 28, 2011 10:17 AM
To: Lawyer, Mike
Cc: Michael Neal
Subject: Tylers Ridge
Mike,
I have a question regarding Tylers Ridge per your comments:
1. comment 6. Regarding the bio-retention supplement forms, pre/post calculations are not required under the
HQW program. I believe this is required by the Town of Southern Pines, but does not need to be shown on the
state forms. As already noted on the supplement forms, you must bypass stormwater flow in excess of the
design volume and provide a vegetated filter for the excess flow. In addition, you need to provide the inlet

velocity or show the use of energy dissipating devices and the values for the separation of IWS and surface for
cells 3 & 4.
For the by-pass of a bioretention area, I assume the primary outlet structure acts as the bypass. Therefore
ston-nwater would only discharge or bypass the basin when it reached the weir of the outlet box (12" deep in the
basin). This would be an 'online" basin as described in the DENR BMP manual. The basins will effectiviely
treat more than the 1 st inch of rainfall. If this is acceptable, I will need a vegetative filter strip at the pipe
outlet. Is this accepatable for bypassing the basins, as long as there are filter strips?
Thank you for your help,
Benjamin Lennon, PE
Michael A. Neal & Associates
105 West Corbin Street, Suite 201
Hillsborough, NC 27278
(919)-644-1277
2

Lawyer, Mike
From: Lawyer, Mike
Sent: Tuesday, November 08, 2011 12:40 PM
To: [e-mail]. [e-mail]
Cc: 'Lou Sadler'
Subject: RE: Tyler's Ridge
Gentlemen,
I have conducted a preliminary review of the stormwater management permit application for Tyler's Ridge and have the
following comments/request for additional information.
1. As an FYI, item 1112 and item IX on the main application form did not need to be completed per the instructions of item
1111c. This does not need to be corrected, but considered for future reference.
2. The project area shown under item IV7 is 33.08 acres and with the proposed density of 23.2%calculates 334,304sf of
BUA, however the attached table adds up to a total of 323,779sf and the narrative and Deed Restrictions show a .
maximum BUA of 338,897sf. The amount of BUA needs to be consistent throughout the application package.
3. The attached table of drainage areas and proposed BUA does not include the BUA breakdown for buildings, roads,
etc. as would be indicated in the table in the application.
4. The attached table only shows a total drainage area of 689,080sf, which does not account for the entire project area
of 1,440,965sf (33.08acres x 43,560sf/ac). You must account for the drainage of the entire project area.
5. The topographic map shows open waters and the site plans show a 30' perennial stream setback. You must exclude
the surface area of any water bodies from the project area. If this has been done please indicate so, otherwise you must
calculate those surface areas and show their exclusion from the project area. The surface area of non -coastal wetlands
can still be included.
6. Regarding the bio-retention supplement forms, pre/post calculations are not required under the HOW program. I
believe this is required by the Town of Southern Pines, but does not need to be shown on the state forms. As already
noted on the supplement forms, you must bypass stormwater flow in excess of the design volume and provide a
vegetated filter for the excess flow. In addition, you need to provide the inlet velocity or show the use of energy
dissipating devices and the values for the separation of IWS and surface for cells 3 & 4.
7. The narrative states that a portion of the entrance drive (Fen Court) runoff cannot be treated due to grades and space
limitations. All runoff from areas within the project area must be treated.
8. Plan sheet C-5 shows an area to the northwest with a drainage Swale and pipe that does not enter the bio-retention
basin #4. Please explain. Again, all runoff must be accounted for and treated.
These items need to be addressed prior to any further review. Please provide this information to this office by December
8, 2011, or the application will be returned as incomplete, which would require re -submittal of all items including the
application/review fee. If you need additional time to submit this information, please provide a request for an extension
of time and indicate the date by which you expect to have all requested information..
If there are any questions, please contact me.
Mike
Michael Lawyer, CPSWQ
Environmental Specialist
NCDENR-Division of Water Quality
Surface Water Protection Section
Fayetteville Regional Office
Direct: [phone]
Main: [phone]

Fax: [phone]
e-mail: [e-mail]
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed
to third parties unless the content is exempt by statute or other regulation.
From: Lou Sadler[mailto:[e-mail]]
Sent: Monday, October 31, 2011 9:12 AM
To: Lawyer, Mike
Cc: [e-mail]; [e-mail]
Subject: RE: Tyler's Ridge
Mike,
Thanks for letting me know you received the submittal. I will be out of the Country from 11/3 to 11/20 on vacation. If
you have any questions about the stormwater plans please feel free to contact our civil engineer directly. They prepared
the plans and calculations and can probably be more informative than I can about them. I have copied both Mike and
Ben so you will have their email addresses. Their phone #i is 1-919-644-1277.
Thanks again, Lou
From: Lawyer, Mike [mailto:[e-mail]]
Sent: Friday, October 28, 2011 1:15 PM
To: Lou Sadler
Subject: Tyler's Ridge
Lou,
The purpose of this e-mail is simply to acknowledge receipt of the Stormwater Management Permit application package
for the subject project by our office on 10/26/11. A review of the application materials and information has not been
conducted. Should I have any questions or need additional information I will contact you.
Thanks,
Mike
Michael Lawyer, CPSWQ
Environmental Specialist
NCDENR-Division of Water Quality
Surface Water Protection Section
Fayetteville Regional Office
Direct: [phone]
Main: [phone]
Fax: [phone]
e-mail: [e-mail]
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be disclosed
to third parties unless the content is exempt by statute or other regulation.

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STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
AT
DIVISION OF WATER QUALITY
HIGH DENSITY DEVELOPM
In accordance with the pro 'sions of Article 21 of Chapter 143, General Statutes of North Carolina as
amended, and other applicab Laws, Rules, and Regulations
P MISSION IS HEREBY GRANTED TO
Steve eBolt & Village o/ Whisl4ring Pines
New Maintenanc uilding_for the Villa e o r /Whispeing Pines
Moore
FOR
construction, operation, and maintenance of an ifiltrafion basin in compliance with the provisions of
15A NCAC 2I-1 .1000 (hereafter referred to as th "sloronvater rules") and the approved stormwater
management plans and specifications and other su porting data as attached and on file with and
approved by the Division of Water Quality and coiVNdered a part of this permit.
This permit shall be effective from the date 6f i
the following specified conditions and limitatio
1. DESIGN STANDARDS
This permit is effective only with respect to the
the application and other supporting/data.
until February 18, 2020, and shall be subject to
2. This stormwater system has been approved for the managt
described in Section 1.6. of this permit. The stormwater co
runoff from 28,950 square feet of impervious area. This b�
vegetated filter.
3. The tract will be limited to the amount of built -upon area i
and per approved plans.
volume of stormwater described in
it of stormwater runoff as
I has been designed to handle the
mist be operated with a 30'
in Section 1.6. of this permit
4. All stormwater collection and treatment systems must be located in either dedicated common
areas or recorded easements. The final plats for the project will be recorded showing all such
required easements in accq'rdance with the approved plans.
5. The runoff from all builtf`vpon area within the permitted drainage area of this project must be
directed into the permitted stormwater control system.
6. The following design criteria has been provided in the infiltration basin and must be maintained
at design condition:

/j;// C ree-k
TYLERS RIDGE AT SANDHILLS DWQ B SIN INFORMATION TABLE
REVISED 12-7-11
BASIN INFORMATION
BMP #1
BMP #2
BMP #3
BMP #4
BMP#5
RLMAINING
AREA
(UNTREATED):
GRAND
TOTAL (SF):
RECEIVING STREAM NAME:
Mill Creek
Mill Creek
Mill Creek
Mill Creek
Mill Creek
Mill Creek
STREAM CLASS:
WSIII; HQW:@
WSIII; HQW:@
WSIII; HQW:@
WSIII; HOW:@
WSIII; HQW:@
WSIII; HQW:@
STREAM INDEX NUMBER:
18-23-11-(1)
18-23-11-(1)
18-23-11-(1)
18-23-11-(1)
18-23-11-(1)
18-23-11-(1)
TOTAL DRAINAGE AREA SF):
304,062
167,565
100,773
108,576
18,648
771,924
1,471,548
ON -SITE DRAINAGE AREA (SF):
304,062
167,565
88,760
108,576
18,648
771,924
1,459,535
OFF -SITE DRAINAGE AREA (SF):
0
0
12,013
0
0
0
12,013
EXISTING IMPERV. AREA (SF):
0
0
0
0
0
0
0
PROP. IMPERV. (TOTAL) (SF):
169,221
65,982
30,037
51,339
9,457
0
326,036
% IMPERVIOUS AREA (total):
55.70%
39.40%
33.80%
47.30%
50.71%
0.00%
22.70%
IMPERVIOUS SURFACE AREA
BUILDINGS/LOTS (SF):
27,217
26,227
20,853
0
0
0
74,297
STREETS (SF):
30,291
0
0
18,398
8,002
0
56,691
PARKING (SF):
46,157
27,394
6,788
0
0
0
80,339
SIDEWALKS (SF):
13,029
6,340
1,312
0
1455
0
22,136
OTHER (SF):
7,830
6,021
1,084
0
0
0
14,935
FUTURE (SF):
44,697
0
0
32,941
0
0
77,638
OFF -SITE (SF)
0
0
0
0
0
0
0
EXISTING BUA (SF)
0
0
0
0
0
0
0
TOTAL (SF)
169,221
65,982
30,037
51,339
9,4571
0
326,036
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BIORETENTION BASINWORKSHEET
Volume of Runoff Required to be Controlled
Simple Method (Ref. NC BMP Manual, pg3-3; July 2007)
Project: TYLER'S RIDGE
Basin ID BIO-BASIN 45 - DRAINAGE AREA 5
Date 11/28/11
Total Catchment area 0.428 acres 18,648 sq. ft.
Total impervious area 0.220 acres 9,587 sq. ft.
Desgin Storm 1 inch
Rv = 0.05+(0.9*IA)
Where
Rv = Runoff coefficient (storm runoff (in)/storm rainfall (in)
IA = Impervious fraction (Impervious portion of drainage aera (ac)/drainage area (ac)
Rv= 0.05+(0.9*IA) 0.51
Volume= 3630*Ri)*Rv*A 797 CP
In -Situ Soils Permeability (in/hr.)
Reference "Soil Survey of Orange County, NC" USDA
If permeability is less than 0.06 in/hr, consider using sub -drainage system.
Reference"stormwater Best Management Practices" NCDENR 1999
Basin Surface Area Calculation:
Ponding Depth: 12 in
Basin Area = DesignVol (1`0)/Ponding Depth (ft)
Basin Area = 797 ftZ

BIORETENTION BASINWORKSHEET
Volume of Runoff Required to be Controlled
Simple Method (Ref. NC BMP Manual, pg3-3; July 2007)
Project: TYLER'S RIDGE
Basin ID BIO-BASIN #1 - DRAINAGE AREA 1
Date 11/2/11
Total Catchment area 6.980 acres 304,062 sq. ft.
Total impervious area 3.885 acres 169,221 sq. ft.
Desgin Storm 1 inch
Rv = 0.05+(0.9*IA)
Where
Rv = Runoff coefficient (storm runoff (in)/storm rainfall (in)
IA = Impervious fraction (Impervious portion of drainage aera (ac)/drainage area (ac)
Rv = 0.05+(0.9*IA) 0.55
Volume = 3630*Ri)*IZv*A 13,959 CP
In -Situ Soils Permeability (in/hr.)
Reference "Soil Survey of Orange County, NC" USDA
If permeability is less than 0.06 in/hr, consider using sub -drainage system.
Reference "stormwater Best Management Practices" NCDENR 1999
Basin Surface Area Calculation:
Ponding Depth: 12 in
Basin Area = DesignVol (ft )/Ponding Depth (ft)
Basin Area = 13,959 ftZ

BIORETENTION BASINWORKSHEET
Volume of Runoff Required to be Controlled
Simple Method (Ref. NC BMP Manual, pg3-3; July 2007)
Project: TYLER'S RIDGE
Basin ID BIO-BASIN #2 - DRAINAGE AREA 2
Date 2/1/12
Total Catchment area 6.160 acres 268,338 sq. ft.
Total impervious area 2.204 acres 96,019 sq. ft.
Desgin Storm 1 inch
Rv = 0.05+(0.9*IA)
Where
Rv = Runoff coefficient (storm runoff (in)/storm rainfall (in)
1A = Impervious fraction (Impervious portion of drainage aera (ac)/drainage area (ac)
Rv = 0.05+(0.9*IA) 0.37
Volume = 3630*RID*Rv*A 8,320 CF
In -Situ Soils Permeability (in/hr.)
Reference "Soil Survey of Orange County, NC" USDA
If permeability is less than 0.06 in/hr, consider using sub -drainage system.
Reference "stormwater Best Management Practices" NCDENR 1999
Basin Surface Area Calculation:
Ponding Depth: 12 in
Basin Area = DesignVol (ft)/Ponding Depth (ft)
Basin Area = 5,320 ft2

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BIORETENTION BASINWORKSHEET
Volume of Runoff Required to be Controlled
Simple Method (Ref. NC BMP Manual, pg3-3; July 2007)
Project: TYLER'S RIDGE
Basin ID BIO-BASIN C4 - DRAINAGE AREA 4
Date 11/2/11
Total Catchment area 5.651 acres 246,145 sq. ft.
Total impervious area 1.500 acres 65,339 sq. ft.
Desgin Storm 1 inch
Rv = 0.05+(0.9*IA)
Where
Rv = Runoff coefficient (storm runoff (in)/storm rainfall (in)
IA = Impervious fraction (Impervious portion of drainage aera (ac)/drainage area (ac)
Rv = 0.05+(0.9*IA) 0.29
Volume = 3630*Rt)*Rv*A 5,926 CF
In -Situ Soils Permeability (in/hr.)
Reference "Soil Survey of Orange County, NC" USDA
If permeability is less than 0.06 in/hr, consider using sub -drainage system.
Reference "stormwater Best Management Practices" NCDENR 1999
Basin Surface Area Calculation:
Ponding Depth: 12 in
Basin Area = DesignVol (fC)/Ponding Depth (ft)
Basin Area = 5,926 ftZ

BIORETENTION BASINWORKSHEET
Volume of Runoff Required to be Controlled
Simple Method (Ref. NC BMP Manual, pg3-3; July 2007)
Project: TYLER'S RIDGE
Basin ID BIO-BASIN #5 - DRAINAGE AREA 5
Date
Total Catchment area
Total impervious area
Desgin Storm
Rv =
2/1/12
2.150 acres 93,648 sq. ft.
0.985 acres 42,913 sq. ft.
1 inch
0.05+(0.9*IA)
Where
Rv = Runoff coefficient (storm runoff (in)/storm rainfall (in)
IA = Impervious fraction (Impervious portion of drainage aera (ac)/drainage area (ac)
Rv = 0.05+(0.9*IA) 0.46
Volume= 3630*R1)*Rv*A 3,609 CF
In -Situ Soils Permeability (in/hr.)
Reference "Soil Survey of Orange County, NC" USDA
If permeability is less than 0.06 in/hr, consider using sub -drainage system.
Reference "stormwater Best Management Practices" NCDBNR 1999
Basin Surface Area Calculation:
Pond ing Depth: 12 in
Basin Area = Design Vol (W)/Ponding Depth (ft)
Basin Area = 3,609 ft2