20071522 Ver 1_More Info Received_20071010

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1~ JOHN R. McADAMS COMPANY, INC.
LETTER OF TRANSMITTAL
To: Ms. Lia Myott Date: October 09, 2007
NCDWQ
401 Wetlands Unit
2321 Crabtree Boulevard
Raleigh, North Carolina 27604
Re: Porto Fino -Clayton, NC
DWQ Response to Comments
I am sending you the following item(sl~
COPIES DATE NO. DESCRIPTION
1 Co of Comment Ltr dated 10/04/07 EXP # 07-1522
3 Bioretention worksheets
3 Revised Construction Notes
3 Revised O eration and Maintenance A reement
These are transmitted as checked below:
® As requested
® For approval
Remarks:
Copy to:
EXP # 07-1522
Kevin Yates
Project Manager
FOR INTERNAL USE ONLY
^ Copy Letter of Transmittal Only to File
® Copy Entire Document to File
CIVIL ENGINEERING • LAND PLANNING • SURVEYING
PO Box 14005 • Research Triangle Park, NC 27709 • [phone] • fax [phone]
www.johnrmcadams.com
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** HAND DELIVER **
Job No.: WLT-07010
® For your use
Signed:

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October 4, 2007
EXPRESS REVIEW NOTIFICATION LETTER
Mr. Rob Bailey
442 %-East Main St.
Clayton, NC 27520
Project Name: Porto Fino Residential Subdivision
D"ear Mr. Bailey:
Michael F. Easley, Governor
William G. Ross 3r., Secretary
North Carolina Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division of water Quality
On October 3, 2007, the Express Review Program of the Division of Water Quality (DWQ} received additional
information from Kevin Yates of.Iohn R. McAdams Company, Inc. The DWQ has determined that this information
is incomplete. Please provide the fo[[owing information so that we may continue to review your project and
prevent denial of your application as required by 15A NCAC 2H .0506:
Diffuse Flow Provisions as required by the Neuse Riparian Buffer Rule:
a. Please provide the supplements (worksheets} for the proposed Bioretention cells. These supplements
can be found at: http://h2o.em•.state.nc.us(sufdocuments/SW401-Bioretention-Rev.l.xls
2. Bioretention cells:
a. Please specify in construction notes that centipede grass sod must be used.
b. Specified P-Index for soil media should be between IO and 30 (see supplement).
3. Operation and Maintenance Agreement:
a. Fertilization is not allowed in a nutrient sensitive watershed except minimal use during the initial
establishment of vegetation (if needed).
b. Remove references to "vegetation and mulch" "mulch layer" and "trees" in Section IV and specify
conditions for centipede sod.
Please respond within five (5} days of the date of this letter by sending three (3) copies of this information. The
Express Review Program is a process. that requires all parties to participate in a timely manner.
This letter only addresses the application review and does not authorize any impacts to wetlands, waters or protected
buffers. Please contact Lia Myott at (919} 733-9502 if you have any questions.
Sincerely,
Cyndi Karoly, Supervisor
401/Express Review Oversite Unit
CBIC/lefla/jg
4010versight/Express Review Permittinng Unit
1650 tvlaitService Center, Ralogh, North GaroHna 21699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carona 21604
Phone: [phone] /FAX [phone]nternel: http:fAt2o_errrstatc,nc.us/ncwctlaads
N°hcarolina
dVaturn~ly
An Equal OpporirxiityfABumative Action Employer - 50% Recycled110% Post Consumer Paper

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cc: DWQ Raleigh Regional Office
DLR Raleigh Regional Office
USAGE Raleigh Field Office
Central Files
File copy
Kevin Yates, John R. McAdams Company, 2905 Meridian Pkwy., Durham, NC 27713

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NCDENR
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Permit Number:
(to be provided by DWQ)
o~~F W A 1'F9OG
O 'c
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out on line, printed and submitted with all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Part III) and the 1&M Agreement (Part IV)
I. PROJECT INFORMATION
Project name Flowers Tract
Contact name Sabrina E. Davis
Phone number 919-550-4740
Date September 24, 2007
Drainage area number 1
II. DESIGN INFORMATI
Site Characteristics
Drainage area 174,498 ft
Impervious area 22,000 ftz
Percent impervious 0.13
Design rainfall depth 1.0 inch
Peak Flow Calculations
Does this project require pre/post control of the 1-yr 24-hr peak n (Y or N)
flow?
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity inlhr
Pre-development 1-yr, 24-hr runoff ft3/sec
Post-development 1-yr, 24-hr runoff ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/~
Storage Volume: Non-SR Waters
Design volume 1,163.0 ft3
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 1,166.0 ftz OK
Length: 53 ft OK
Width: 22 ft OK
-or- Radius ft
Storage Volume: SR Waters
1-yr, 24-hr depth in
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Soils Report Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown time, total: 48 hr
In-situ soil.•
Soil type Parcolet Loam
Soil permeability 0.60 in/hr
Planting media soil.•
Soil type Sandy Loam
Soil permeability 1.00 in/hr OK
Soil composition
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 1 of 3

Permit Numt~er:
(to be provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Planting depth
Depth of mulch
SHWT elevation
Are underdrains being installed?
85% OK
12% OK
3% OK
Total: 100%
30 (unitless) OK
231 fmsl OK
229.5 fmsl
227 fmsl
2.5 ft
2 inches OK
216 fmsl OK
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?
Is this a cell with trees/shrubs?
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
through a vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA
waters)?
Is the BMP located at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
y (Y or N)
2 OK
10
1ft
226 fmst
10 ft OK
y (Y or N) OK
n (Y or N)
y (Y or N)
n (Y or N) Excess volume must pass through filter.
ft
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N)
y (Y or N)
ft/sec
n (Y or N)
Are the slopes draining to the bioretention cell greater than 20%? n (Y or N)
Is the drainage area permanently stabilized? y (Y or N)
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(flinches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
OK
OK
OK
OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 2 of 3

Permit Number:
(to be provided by DWQ)
Attach supporting calculations/documentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-Bioretention-Rev.1 Parts 1 and II. Design Summary, Page 3 of 3

Permit Number:
(to be provided by DWQ)
O~O~ W A TF9OG
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NCDENR p
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out on line, printed and submitted w-th all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Pa-t III) and the 1&M Agreement (Part IV)
I. PROJECT INFORMATION
Project name Flowers Tract
Contact name Sabrina E. Davis
Phone number 919-550-4740
Date September 24, 2007
Drainage area number 2
II. DESIGN INFORMATION
Site Characteristics
Drainage area 24,820 ft
Impervious area 3,300 ft
Percent impervious 0.13
Design rainfall depth 1.0 inch
Peak Flow Calculations
Does this project require prelpost control of the 1-yr 24-hr peak n (Y or N)
flow?
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr runoff ft3/sec
Post-development 1-yr, 24-hr runoff ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SR Waters
Design volume 268.0 ft3
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 300.0 ft2 OK
Length: 25 ft OK
Width: 12 ft OK
-or- Radius ft
Storage Volume: SR Waters
1-yr, 24-hr depth in
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Soils Report Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown time, total: 48 hr
IR-SItU S011:
Soil type Parcolet Loam
Soil permeability 0.60 inlhr
Planting media soil:
Soil type Sandy Loam
Soil permeability 1.00 in/hr OK
Soil composition
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 1 of 3

Permit Number.
(to be provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Planting depth
Depth of mulch
SHWT elevation
Are underdrains being installed?
85% OK
12% OK
3% OK
Total: 100%
30 (unitfess) OK
232.5 fmsl OK
231.5 fmsl
229 fmsl
2.5 ft
2 inches OK
216 fmsl OK
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?
Is this a cell with treeslshrubs?
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
through a vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA
waters)?
Is the BMP located at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
Are the slopes draining to the bioretention cell greater than 20%?
Is the drainage area permanently stabilized?
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(flinches gravel followed by 3-5 ft of grass)
Grassed Swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
y (Y or N)
2 OK
10
1ft
228 fmsl
12 ft OK
y (Y or N) OK
n (Y or N)
y (Y or N)
n (Y or N) Excess volume must pass through filter.
ft
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N) OK
y (Y or N) OK
ft/sec
n (Y or N)
n (Y or N) OK
y (Y or N) OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 2 of 3

Permit Number:
(to be provided by DWQ)
Attach supporting calculations/documentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 3 of 3

Permit Number:
(to be provided by DWQ)
O~o~ W A 7E9Qv
~ r
~~ ~ ti
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out on line, printed and submitted with all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Part III) and the 1&M Agreement (Part IV)
I. PROJECT INFORMATION
Project name Flowers Tract
Contact name Sabrina E. Davis
Phone number 919-550-4740
Date September 24, 2007
Drainage area number 3
II. DESIGN INFORMATION
Site Characteristics
Drainage area 32,131 ftZ
Impervious area 4,600 ft2
Percent impervious 0.14
Design rainfall depth 1.0 inch
Peak Flow Calculations
Does this project require prelpost control of the 1-yr 24-hr peak
flow?
1-yr, 24-hr runoff depth
1-yr, 24-hr intensity
Pre-development 1-yr, 24-hr runoff
Post-development 1-yr, 24-hr runoff
Pre/Post 1-yr, 24-hr peak control
Storage Volume: Non-SR Waters
Design volume
Ponding depth of water
Ponding depth of water
Surface area of the top of the bioretention cell
Length:
Width:
-or- Radius
Storage Volume: SR Waters
1-yr, 24-hr depth
Pre-development 1-yr, 24-hr runoff
Post-development 1-yr, 24-hr runoff
Minimum volume required
Volume provided
Soils Report Summary
Drawdown time, ponded volume
Drawdown time, to 24 inches below surface
Drawdown time, total:
In-situ soil.•
Soil type
Soil permeability
Planting media soil:
Soil type
Soil permeability
Soil composition
n (Y or N)
In
inihr
ft3/sec
ft3/sec
ft3/sec
349.0 ft3
12 inches OK
1.00 ft
350.0 ftz OK
25 ft OK
14 ft OK
ft
in
ft3
ft3
ft3
ft3
12 hr OK
36 hr OK
48 hr
Parcolet Loam
0.60 in/hr
Sandy Loam
1.00 inihr OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 1 of 3

Permit Number:
(to be provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Planting depth
Depth of mulch
SHWT elevation
Are underdrains being installed?
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?
Is this a cell with trees/shrubs?
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
through a vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA
waters)?
Is the BMP located at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
Are the slopes draining to the bioretention cell greater than 20%? n (Y or N)
Is the drainage area permanently stabilized? y (Y or N)
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(flinches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
85% OK
12% OK
3% OK
ivuio
30 (unitless) OK
222.0 fmsl OK
221 fmsl
218.5 fmsl
2.5 ft
2 inches OK
180 fmsl OK
Total:
y (Y or N)
1 OK
10
1ft
217.5 fmsl
37.5 ft OK
y (Y or N) OK
n (Y or N)
y (Y or N)
n (Y or N) Excess volume must pass through filter.
ft
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N)
y (Y or N)
ft/sec
n (Y or N)
OK
OK
OK
OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 2 of 3

Permit Number.
(to be provided by DWG
Attach supporting calculations/documentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-Bioretention-Rev.1 Parts 1 and II. Design Summary, Page 3 of 3

Permit Number:
(to be provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Planting depth
Depth of mulch
SHWT elevation
Are underdrains being installed?
85% OK
12% OK
3% OK
Total: 100%
30 (unitless) OK
222.0 fmsl OK
221 fmsl
218.5 fmsl
2.5 ft
2 inches OK
180 fmsl OK
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
folbwing questions):
Is this a grassed cell?
Is this a cell with trees/shrubs?
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
through a vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA
waters)?
Is the BMP localed at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
Are the slopes draining to the bioretention cell greater than 20%?
Is the drainage area permanently stabilized?
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(flinches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
y (Y or N)
1 OK
10
1ft
217.5 fmsl
37.5 ft OK
y (Y or N) OK
n (Y or N)
y (Y or N)
n (Y or N) Excess volume must pass through filter.
ft
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N) OK
y (Y or N) OK
ft/sec
n (Y or N)
n (Y or N) OK
y (Y or N) OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 2 of 3

Permit Number:
(to be provided by DWQ)
Attach supporting calculations/documentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-eioretention-Rev.1 Parts I and II. Design Summary, Page 3 of 3

Permit Number:
(to be provided by OWQ)
O~~F W A TE9OG
©~~
__
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out on line, printed and submitted with all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Part 111J and the 1&M Agreement (Part IV)
I. PROJECT INFORMATION
Project name Flowers Tract
Contact name Sabrina E. Davis
Phone number 919-550740
Date Septemt~er 24, 2007
Drainage area number 5
II. DESIGN INFORMATION
Site Characteristics
Drainage area 41,495 ftZ
Impervious area 6,100 ftz
Percent impervious 0.15
Design rainfall depth 1.0 inch
Peak Flow Calculations
Does this project require prelpost control of the 1-yr 24-hr peak n (Y or N)
flow?
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr runoff ft3/sec
Post-development 1-yr, 24-hr runoff ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SR Waters
Design volume 449.5 ft3
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 450.0 ft OK
Length: 30 ft OK
Width: 15 ft OK
-or- Radius ft
Storage Volume: SR Waters
1-yr, 24-hr depth in
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Soils Report Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown time, total: 48 hr
In-situ soil:
Soil type Parcolet Loam
Soil permeability 0.60 inlhr
Planting media soil:
Soil type Sandy Loam
Soil permeability 1.00 in/hr OK
Soil composition
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 1 of 3

Permit Number:
(to 6e provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Pianting depth
Depth of mulch
SHWT elevation
Are underdrains being installed?
Total:
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?
Is this a cell with trees/shrubs?
Additional Information
Does volume in excess of the design volume bypass the
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
through a vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA
waters)?
Is the BMP localed at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
Are the slopes draining to the bioretention cell greater than 20%?
Is the drainage area permanently stabilized?
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(8'inches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
85% OK
12% OK
3% OK
~„ ,,,
30 (unitless) OK
213.0 fmsl OK
212 fmsl
209.5 fmsl
2.5 ft
2 inches OK
185 fmsl OK
y (Y or N)
1 OK
10
1ft
208.5 fmsl
23.5 ft OK
y (Y or N) OK
n (Y or N)
y (Y or N)
n (Y or N) Excess volume must pass through filter.
ft
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N) OK
y (Y or N) OK
ftlsec
n (Y or N)
n (Y or N) OK
y (Y or N) OK
Form SW401-Bioretention-Rev.1 Pans I and II. Design Summary, Page 2 of 3

Permit Number:
(to be provided by DWQ)
Attach supporting calculationsldocumentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-Bioretention-Rev.t Parts I and II. Design Summary, Page 3 of 3

Permit Number:
(to be provided by DWQ)
®. O~o~ W ATF9OGv
r
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out on line, printed and submitted with all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Part Ill) and the I&M Agreement (Parf IV)
I. PROJECT INFORMATION
Project name Flowers Tract
Contact name Sabrina E. Davis
Phone number 919-550-4740
Date September 24, 2007
Drainage area number 6
II. DESIGN INFORMATION
Site Characteristics
Drainage area 47,040 ftZ
Impervious area 6,500 ft2
Percent impervious 0.14
Design rainfall depth 1.0 inch
Peak Flow Calculations
Does this project require pre/post control of the 1-yr 24-hr peak n (Y or N)
flow?
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr runoff ft3/sec
Post-development 1-yr, 24-hr runoff ft3/sec
PrelPost 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SR Waters
Design volume 508.5 ft3
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 512.0 ft OK
Length: 32 ft OK
Width: 16 ft OK
-or- Radius ft
Storage Volume: SR Waters
1-yr, 24-hr depth In
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required ft3
Volume provided ft3
Soils Report Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown time, total: 48 hr
In-situ soih.
Soil type Parcolet Loam
Soil permeability 0.60 in/hr
Planting media soil:
Soil type Sandy Loam
Soil permeability 1.00 in/hr OK
Soil composition
Form SW401-Bioretention-Rev.1 Parts 1 and II. Design Summary, Page 1 of 3

Permit Number:
(to be provided by DWQ)
Sand (by weight)
Fines (by weight)
Organic (by weight)
Phosphorus Index (P-Index)
Basin Elevations
Temporary pool elevation
Planting elevation (top of the mulch)
Bottom of the cell
Planting depth
Depth of mush
SHWT elevation
Are underdrains being installed?
85% OK
12% OK
3% OK
Total: 100%
30 (unifless) OK
211.0 fmsl OK
210 fmsl
207.5 fmsl
2.5 ft
2 inches OK
185 fmsl OK
How many clean out pipes are being installed?
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and
the bottom of the cell to account for underdrains
Bottom of the cell required
Distance from bottom to SHWT
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell?
Is this a cell with treeslshrubs?
y (Y or N)
1 OK
10
1tt
206.5 fmsl
29.5 tt OK
y (Y or N) OK
n (Y or N)
Additional Information
Does volume in excess of the design volume bypass the y (Y or N)
bioretention cell?
Does volume in excess of the design volume flow evenly distributed n (Y or N) Excess volume must pass through filter.
through a vegetated filter?
What is the length of the vegetated filter? tt
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50tt if SA
waters)?
Is the BMP localed at least 100tt from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a recorded drainage easement with a
recorded access easement to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
Is the area surrounding the cell likely to undergo development in
the future?
Are the slopes draining to the bioretention cell greater than 20%?
Is the drainage area permanently stabilized?
Pretreatment Used
(Indicate Type Used with an "X" in the shaded cell)
Gravel and grass
(8`inches gravel followed by 3-5 tt of grass)
Grassed swale
Forebay
Plants
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
n (Y or N) Show how flow is evenly distributed.
y (Y or N)
y (Y or N)
y (Y or N) OK
y (Y or N) OK
ftlsec
n (Y or N)
n (Y or N) OK
y (Y or N) OK
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 2 of 3

Permit Number:
(to be provided by DWQ)
Attach supporting calculations/documentation. The soils report must be based upon an actual field investigation, soil borings, and infiltration tests. The results of the
soils report must be verified in the field by DWQ, by completing & submitting the soils investigation request form. County soil maps are not an acceptable source of
soils information. All elevations shall be in feet mean sea level (fmsl).
Form SW401-Bioretention-Rev.1 Parts I and II. Design Summary, Page 3 of 3

~ x p o'~ - 5 2 2
PORTO FIND
Clayton, NORTH CAROLINA _
BIORETENTIONAREAS # 1-6
OPERATION AND MAINTENANCE
AGREEMENT (Revised 10/05/07)
WLT-07010
October 2007

SECTION I
MAINTENANCE OF EMBANKMENTS
~~

I. MAINTEN~iNCE OFBIORETENTIONAREA EMBANSMENTS
A. Vegetation
The primary vegetative ground cover for all berm/embankments
(excluding inside the wet pond facility) is to be tall fescue. Proper
maintenance of this cover will serve to prevent erosion while providing
optimal access for inspection as well as preventing excessive sediment
from entering the facility. Woody vegetation and trees should not be
allowed to propagate on the dam embankments or top of dam. Trees and
brush, if desired, are acceptable on embankments other than the dam.
Inspection of embankment centipede sod condition should be performed
monthly or after every rainfall event greater than 0.5 inches of rainfall
over a 24-hour period.
1. Seeding: Seeding should be accomplished by the use of a spiker
and large tractor aerifier to ensure proper seed and soil contact
along the top of banks. The temporary and permanent seeding
schedules are shown on the bioretention area detail sheet, which
has been included within this manual. Reseeding may be
necessary in instances where initial seeding failed or existing
areas have been compromised. The seeding schedules shown on
the original design documents for the bioretention area should be
followed for any necessary reseeding.
2. Mowing: All vegetative cover should be maintained below 6" in
height. Due to the slope of the embankments, string trimmers
(no mechanical mowers) must be utilized for mowing turf.
Mowing and maintenance should be performed once a month to
keep the maximum grass height below 6 inches and to maintain
appropriate turf cover and health of turf.
B. Erosion
Erosion is initiated when vegetative cover is insufficient and/or
concentration of runoff destabilizes centipede sod. Runoff then tends to
concentrate into channel flow, and soils tend to become entrained in the
water and be transported downstream. Unsuitable fill material,
inadequate compaction, and/or poor stabilization of centipede sod can
accelerate the erosion process. This has a negative environmental impact
on downstream features, and has the potential to undermine the stability
of the wet pond. facility. Erosion can be minimized with the proper care
of centipede sod and the use of appropriate methods to repair eroded
areas and prevent recurrences of eroded areas. Appropriately, compacted
soil meeting the berm design requirements will be placed in any gullies
or rills, and then reseeded as described above. Re-occurrence of erosive
problems should be addressed with appropriate geotextile fabrics that are
installed according to manufacturer's instructions and per an engineer's
recommendation. Uneven surfaces on the crest of the berm may lead to
the formation of rills and/or gullies. It is possible to eliminate this
problem by properly filling any depressed areas such that the entire top
of berm is flat and level. Addition of fill to the top of berm should be
completed by first preparing the existing soil such that a distinct

boundary layer does not form beneath existing soil and newly placed soil.
New fill should meet all soil requirements (as to material, placement, and
compaction) as stated on the original design documents for this structure.
Inspection for erosion should be performed monthly or after every major
rainfall- event.
Abutment (or toe) areas: The location where the fill of the berm
contacts the existing ground is the abutment (or toe). Erosive
channels have a tendency to form in these areas. Appropriate
geotextile fabrics, as mentioned above, may be necessary to
prevent or stop this form of erosion from occurring. An engineer
is required if erosion in this area is significant.
C. Seepage
1. Detection: Soft wet areas and. flowing springs are an indication
of seepage. Early indicators of seepage include vegetation which
is more robust than surrounding centipede sod. Vegetation
normally associated with wetland areas such as cattails, ferns,
reeds- and mosses may also indicate the initiation of seepage.
The previously described abutment (or toe) area is a common
location for seepage to occur. Another common location for
seepage problems is the area where the outlet structure exits the
berm section. This is especially true in cases where the soil
around the barrel is not compacted properly. Another problem
related to seepage may be indicated by the occurrence of `boils'
below the abutment of the dam. These boils are springs that tend
to deposit soils. Locating the occurrence of any boils should be
included in the bi-annual inspection of the facility. `Boils' are a
possible indication of -piping and could lead to berm failure.
Piping occurs when a void space is formed within the interior of
the berm embankment. These void spaces tend to be preferred
- paths for water to travel, which will erode the interior of the
berm and lead to failure.
D. Cracks, Slides, Sloughing and Settlement
Cracks: Large, well-defined cracks of greater than '/a" width
indicate the potential for serious problems and the inspector of
the facility should be alert for their presence. Cracks in the berm
generally follow one of two patterns:
• Transverse cracks appear perpendicular to the length of the
berm and may be caused by differential settlement.
Transverse cracks increase the likelihood of the formation of
piping and seepage.
• Longitudinal cracks appear horizontally along the berm and
could serve as warnings to a future slide event. Longitudinal
cracks in newly constructed berms may be an indication of
poor compaction techniques and poor foundation preparation.
2. Slides: Slides and slumps have the potential to critically
undermine the integrity of the berm. Arch-shaped cracks that

expose soil indicate the initiation of slides. Detection of slides
by inspectors should be addressed in a timely manner and a
geotechnical engineer should be contacted for consultation.
3. Settlement: Settlement of the soil in the berm reduces freeboard
in large storm events and may even lead to overtopping.
Differential settlement of the berm can also lead to the
concentration of runoff and therefore erosion as mentioned
above. For this reason the berm should be maintained uniformly
to its original design elevation. Greater than six inches of
settlement may be indicative of significant issues within the berm
foundation and could lead to catastrophic failure. Indications of
this degree of settlement necessitate inspection by a geotechnical
engineer.
4. Inspections for cracks, slides,_ sloughing, and settlement should
be performed biannually. Actions to take if any of the above is
detected: Any of the problems mentioned above require that a
geotechnical or civil engineer be contacted, and that corrective
action be taken.

SECTION II
SEDIMENT MONITORING

II. SEDIMENT MONITORING
A. Bioretention Area
Accumulation of sediment within the bioretention area should be kept to
a minimum by stabilization of the bioretention drainage area and proper
prevention of erosion. Excess sediment. accumulation within the
bioretention area will cause suffocation. of the bioretention area -
centipede sod, thus crippling the water.._ quality function of the
bioretention area. Inspection for sediment deposition should be
performed biannually.
1. Check the depth at various points within the bioretention area,
especially in the upland areas around the inlets to the
bioretention area. Accumulated sediment will be removed
semiannually or when the depth reaches 0.5 inches or more. A
stake shall be set during construction to indicate 0.5 inches of
- sediment accumulation. The measuring device used to determine
the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated
sediments.
2. Removed sediment shall be disposed of in an appropriate manner
and shall be handled in a manner that will not adversely impact
water quality (i.e. stockpiling -near the bioretention area or
surrounding streams).
3. If the elevation of the bio-retention area bottom exceeds the
planned elevation, the sediment shall be removed to design
levels: This shall be performed by removing the upper 6 inches
of soil and stockpiling the soil. The soil shall not be stockpiled
for more that 2 weeks. Any dead or damaged bio-retention area
plants must be replaced after this process per the original
planting plan.
B. Forebay
Accumulation of sediment within the forebay area should be kept to a
minimum by stabilization of the bioretention area drainage area and
proper prevention of erosion. Excess sediment accumulation within the
forebay area will cause sediment transport to the main pool of the
bioretention area and subsequent difficulty with maintenance procedures.
Inspection for sediment deposition should be performed biannually.
Check the depth at various points within the forebay, especially
in the .upland areas around the inlets to the bioretention area.
Accumulated sediment will be removed semiannually or when
the depth reaches 2 inches or more. A stake shall be set during
construction to indicate 2 inches of sediment accumulation. The
measuring device used to determine the sediment elevation shall
be such that it will give an accurate depth reading and not readily
penetrate into accumulated sediments.

2. Removed sediment shall be disposed of in an appropriate manner
and shall be handled in a manner that will not adversely impact
water quality (i.e. stockpiling near the pond basin or streams).
3. NCDOT class "B" rip-rap is recommended to form the forebay.
This rip-rap shall be replaced annually or when necessary
between annually replacements. Care should be taken to insure
that a 12" lip of rip-rap is maintained at all times .around the
perimeter of the forebay. This lip prevents the occurrence of an
erosive environment. Loss of the lip could result in the loss of
the water quality benefits associated with the bio-retention area.
C. Principal Spillway System
1. If present, remove accumulated sediment from the outlet
structure. The principal spillway system should be inspected for
sediment accumulation monthly or after every rainfall event
greater than 0.5 inches of rainfall over a 24-hour period.
D. Storm Drainage System
1. The upstream storm drainage- system should be maintained along
with the bioretention area. Trash from the site has a tendency to
be washed into the storm drainage system and become lodged in
the catch basins or pipes. The catch basins and pipes should be
cleaned of debris at the time that maintenance is performed on
the bioretention area. Sediment may accumulate in portions of
the storm drainage system where slopes are relatively flat. This
sediment may be washed out of the system, or flushed with a
- garden hose. Sediment shouhi be flushed monthly or after every
rainfall event greater than 0.5 inches of rainfall over a 24-hour
period. Steps should be taken to trap this "flushed" sediment at
the entrance to the bioretention area to prevent it from -being
deposited within the wet pond.

SECTION III
MAINTENANCE OF O UTLET STRUCTURES _
_,~_,

III. MAINTENANCE OF OUTLET STR UCTURES
The bioretention area is designed to pass stormwater quality storms through the
low flow orifice located in the secondary outlet structure and larger storm events
through the principal spillway. It is of vital importance that these structures
remain unblocked so that the hydraulic functionality is not compromised. The
outlet structure system should be inspected to ensure that it is functioning
~.'~• properly.
A. Bio-Retention Underdrain System
1. The underdrain system for both bio-retention areas consists of a
series of 8-inch diameter perforated HDPE pipes. These
underdrain pipes connect to the concrete principal spillway drop
inlet via 8-inch diameter HDPE pipes. Tied to the underdrain
system are vertical HDPE cleanouts that extend up to the surface
of the mulch layer. The underdrain system is wrapped in a
nonwoven geotextile filter fabric and is installed within a gravel
- jacket in order to minimize the probability of blockage.
However, in the event that the underdrain systems become
blocked, the bio-retention area will not drain appropriately and
will tregin to pond up, which means---that the water quality
benefits associated with the bio-retention area are lost. The
underdrain system should be inspected for blockage monthly or
- - after every rainfall event greater than 0.5 inches of rainfall over a
24 hour period. If inspected after a major rainfall event, all
ponded water should dissipate over 4-6 hours. Debris causing
the blockage should be promptly removed from the underdrain
system such that sufficient infiltration through the bio-retention
area may occur. The underdrain systems may be accessed /
flushed out via the HDPE cleanouts located at the top of the
mulch layer.
B. Principal Spillway
1. The principal spillway for the bioretention area consists of a 4' x
-- 4' square weir box structure attached to a 18-inch O-ring RCP
barrel. The principal spillway is responsible for safely
conveying larger storm events through the facility. The principal
spillway system is expected to remain robust throughout the life
of the bioretention area, but periodic inspection of the system is
required. This inspection should occur biannually. The
inspector should check for the presence of spalling, scaling, or
cracking in the spillway system. Spalling is evident when pieces
of concrete fall from the main pipe. It is defined as breaking,
chipping, or fraying of concrete slabs that leave an uneven

surface or edge, most often at joints or cracks. Scaling occurs
when the surface of the concrete begins to flake off. The
presence of cracking is indicated by separations in the concrete
that are not located in the joints. Cracking can indicate the
presence of structural problems and lead to leaks. Cracking can
cause loss of the water tightness of the system, which can lead to
piping (i.e. migration of soil particles into the pipe}. If piping
occurs, the risk of failure of the dam structure is greatly
increased. Evidence. of any of the above issues requires that an
engineer be contacted for additional inspection to determine the
need for repairs.
2. _ If the principal spillway system becomes blocked so that it does
not operate at full capacity, the risk of dam overtopping or other
. uncontrolled releases may result. Therefore, to ensure hydraulic
capacity of the spillways, the principal spillway system should be
_ ..~ inspected for blockage monthly or after each major rainfall
~~ event. -Any vegetative growth that occurs within the principal
spillway system should be removed promptly so that the full
hydraulic capacity of the system is maintained.
C. Stormwater Pipes
1. The underground pipes should be inspected for any structural
damage. Structural damage includes but is not limited to
deterioration, joint failure, punctures, cracks, misalignment,
settling;- leaking, deflection, and sagging. Deformations in the
- ground surface directly above or near the stormwater pipe may
be a sign of failure in the system. Any structural damage
- -- should- be immediately reported to a register professional
engineer so that the appropriate course of action can be
determined.
2. The underground pipes, including inlet and outlet areas, should
be inspected for trash/debris accumulation to ensure runoff can
move freely into and out of the pipes. Any accumulated
trash/debris should be removed and disposed of in an approved
manner.
D. Ground Surface
The ground surface should be inspected for visual signs of sink
holes. If any signs of a sink hole are present, a registered
professional engineer should be immediately consulted for
remediation action.

a.
SECTION IV
MAINTENANCE OF BIO-RETENTION AREA
CENTIPEDE SOD

IY. Maintenance of Bio Retention Area Centipede sod
A. Bio-retention Area Centipede sod
1. Once the construction of the bio-retention area is complete, the
centipede sod should be watered for 14 consecutive days unless
sufficient natural rainfall in order to establish the centipede sod
appropriately.
2. The centipede sod should be visually inspected monthly (more
•- - frequently in the summer) for disease or pest problems. If pest
treatment is necessary, use the least toxic .method. All dead and
diseased centipede sod considered beyond treatment should be
removed and replaced. The centipede sod should be kept healthy
and vibrant. If necessary, it should be over seeded (usually in the
fall -September to October) at a rate of 100 lbs/acre.
3. The grass within the bio-retention area should be mowed to a
height ofno greater than 8 inches.
4. During extreme heat and drought conditions, the centipede sod
should be inspected for physical features of stress (i.e. wilting,
yellow, spotted, loss of, or brown leaves, etc.). During these
conditions, the bio-retention areas should be watered as
necessary.
5. Weeds and other invasive species should be removed whenever
present.
B. Planting Soil Layer
1. The planting soil layer should be visually inspected for
erosion/damage once a month. Evidence of erosion should be
promptly repaired. If erosion is present along the drainage path
within the bio-retention area, it may be stabilized using. small
stones.
2. The pH of the bio-retention area should be checked twice a year.
If necessary, apply an alkaline product (such as limestone) to
maintain the appropriate pH. Please reference the detail sheet for
the bio-retention area included in this report for the appropriate
pH levels.
3. If present, accumulated trash, litter, and debris should be
removed during. the monthly inspection.
4. If present, accumulated sediment .should be removed per the
"Sediment Monitoring" section of this manual.