20061151 Ver 2_Stormwater Plans_20090529

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May 29, 2009
Annette Lucas
Division of Water Quality
401/Wedands Unit
1650 Mail Service Center
Suite 120
Raleigh, NC 27699-1650
RE: Response to Request for More Information; DWQ Project # 06-1151 Y a
Dear Ms. Lucas:
This letter is in response to DWQ's request for more information regarding the Apex Peakway
road project in the Town of Apex, DWQ Project # 06-1151. Enclosed are five (5) copies of the
following:
• Completed Operation and Maintenance Agreement for Bioretention cells
• Full size plan set with sheets 2C, 4, 5, 6 and 7
• Stormwater Management Plan Calculations (Signed and sealed May 29, 2009)
One copy of the project geotechnical report is also enclosed for your reference.
Pleas do not hesitate to call me at [phone] if you have any questions or need
additional information.
Sincerely,
Wilbur Smith Associates

Tom Harris, PE
Project Manager
CC: Russell Dalton, PE - Town of Apex
Project File
Enclosures
421 Fayetteville Street, Suite 1303 Raleigh, NC 27601
919.755.0583 f919.832.8798 www.WilburSmith.com
Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Bioretention 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.
Important operation and maintenance procedures:
- Immediately after the bioretention cell is established, the plants will be watered
twice weekly if needed until the plants become established (commonly six
weeks).
- Snow, mulch or any other material will NEVER be piled on the surface of the
bioretention cell.
- Heavy equipment will NEVER be driven over the bioretention cell.
- Special care will be taken to prevent sediment from entering the bioretention cell.
- Once a year, a soil test of the soil media will be conducted.
After the bioretention cell is established, I will inspect it once a month and within 24
hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal
County). Records of operation and maintenance will be kept in a known set location
and will be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element: Potential problems: How I will remediate the problem:
The entire BMP Trash/debris is resent. Remove the trash/debris.
The perimeter of the Areas of bare soil and/or Regrade the soil if necessary to
bioretention cell 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.
The inlet device: pipe, The pipe is clogged (if Unclog the pipe. Dispose of the
stone verge or swale applicable). sediment off-site.
The pipe is cracked or Replace the pipe.
otherwise damaged (if
applicable).
Erosion is occurring in the Regrade the Swale if necessary to
swale (if applicable). smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
Stone verge is clogged or Remove sediment and clogged
covered in sediment (if stone and replace with clean stone.
a licable .
Form SW401-Bioretention O&M-Rev.3 Page 1 of 4
BMP element: Potential problems: How I will remediate the problem:
The pretreatment area Flow is bypassing Regrade if necessary to route all
pretreatment area and/or flow to the pretreatment area.
gullies have formed. Restabilize the area after grading.
Sediment has accumulated to Search for the source of the
a depth greater than three sediment and remedy the problem if
inches. possible. Remove the sediment and
restabilize the pretreatment area.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
revent future erosion problems.
Weeds are present. Remove the weeds, preferably by
hand.
The bioretention cell: Best professional practices Prune according to best professional
vegetation 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.
Tree stakes/ wires are present Remove tree stake/ wires (which
six months after planting. can kill the tree if not removed).
The bioretention cell: Mulch is breaking down or Spot mulch if there are only random
soils and mulch has floated away. void areas. Replace whole mulch
layer if necessary. Remove the
remaining much and replace with
triple shredded hard wood mulch at
a maximum depth of three inches.
Soils and/or mulch are Determine the extent of the clogging
clogged with sediment. - remove and replace either just the
top layers or the entire media as
needed. Dispose of the spoil in an
appropriate off-site location. Use
triple shredded hard wood mulch at
a maximum depth of three inches.
Search for the source of the
sediment and remedy the problem if
possible.
An annual soil test shows that Dolomitic lime shall be applied as
pH has dropped or heavy recommended per the soil test and
metals have accumulated in toxic soils shall be removed,
the soil media. disposed of properly and replaced
with new lantin media.
Form SW401-Bioretention O&M-Rev.3 Page 2 of 4
BMP element: Potential problems: How I will remediate the problem:
The underdrain system Clogging has occurred. Wash out the underdrain system.
(if applicable)
The drop inlet Clogging has occurred. Clean out the drop inlet. Dispose of
the sediment off-site.
The drop inlet is damaged Repair or replace the drop inlet.
The receiving water Erosion or other signs of -
Contact the NC Division of Water
damage have occurred at the Quality 401 Oversight Unit at 919-
outlet. 733-1786.
Form SW401-Bioretention O&M-Rev.3 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: Apex p
BMP drainage area number-Outlet 22 (Bioretention Cell A) Outlet 27 (Bioretention
Cell B), and Outlet 29 (Bioretention Cell C)
Print name: Bruce A. Radford
Title: Town Manager
Address: PO Box 250, Apex, North Carolina 27502-0250
Phone: [phone]
Signature:
Date:
28, 20
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, Georgia A. Evangelist , a Notary Public for the State of
North Carolina , County of Wake , do hereby certify that
Bruce A. Radford
10-20-2009
day of may , 2009 , and acknowledge the due execution of the
forgoing bioretention maintenance requirements. Witness my hand and official seal,
C,' /
J
SEAL
My commission expires
personally appeared before me this 28th.
?1 -
11
Georgia A. Evangelist v
Notary Public
Form SW401-Bioretention I&M-Rev. 2 Page 4 of 4
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STORMWATER MANAGEMENT
PLAN CALCULATIONS
TOWN OF APEX
APEX PEAKWAY
WSA No. 101673
May 29, 2009
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WilburSmith
A S S O C I A T E S
421 Fayetteville Street, Suite 1303 Raleigh, NC 27601
919.755.0583 f919.832.8798 www.WilburSmith.com
Apex Peakway
Storm Drainage Report
Project Description
Wilbur Smith Associates was selected to provide engineering services for a portion of the Apex
Peakway. This project involves the layout and design for a future multi-lane divided roadway
with curb and gutter and concrete median. The project consists of two railroad crossings, one at
grade and one with a bridge. This portion of the Peakway connects the existing Peakway from
North Salem Street to Old Raleigh Road. Figure 1 contains a project location map.
Purpose
The purpose of this report is to document the design of drainage, erosion and sediment control for
the proposed Apex Peakway.
Existing Condition
The project area consists of both wooded and open fields. The existing slopes in the area are
relatively mild. This existing drainage pattern has been maintained in a closed system.
Proposed Condition
Drainage characteristics for the proposed condition are not changed greatly from the existing
conditions and existing patterns were maintained as closely as possible. The proposed roadway
improvement includes a multi-lane highway with concrete islands and curb and gutter. Roadway
runoff is typically discharged at the same locations as in the existing conditions. Storm drain
pipes calculations are based on the 10-year design storm and inlets are spaced to contain the
spread within one half of the adjacent travel lane for the NCDOT 4 in/hr standard. Culverts are
designed based on the 25-year design storm. All calculations are preformed in accordance with
the NCDOT hydraulic design standards.
Portions of the project are adjacent to newly proposed development and coordination with the
developer has allowed for sections of the Peakway runoff to be discharged into stormwater
treatment facilities designed and constructed by the developer. Where discharging into the
adjacent stormwater ponds was not available bioretention cells will be utilized to meet the
stormwater management plan requirements. These bioretention cells are located at storm
drainage outlets 22, 27, and 29.
The accompanying calculations and methodology used in design are attached.
DRAINAGE AREAS AND
DISCHARGES
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STORMWATER CALCULATIONS
STORM DRAIN DESIGN COMPUTATIONS
May 2009
Description: Apex Peakway County: Wake Designed by: THB
WSA Project No. Checked by: MAD

Inlet No./
Description
From
Structure
Number
To
Structure
Number

Area Cum.
Area
"A'
(acres)
Sum
'CA' Time Of
Conc.
"To.
(min) Rainfall
Intensity
11110'
(in/hr) Total
Runoff
'Q10'
(cfs)
Invert
Inlet Elev
Invert
utlet Elev
Pipe
Slope
(%) Design
Pipe
Size
(in) Design
Full - Pipe
Capacity
(cfs)
Actual
Velocity
(fps)
Travel
Time
(min)

1/CB 1 2 0.24 0.24 0.20 5.00 7.22 1.44 491.54 491.03 0.85 15 5.95 3.99 0.25
3 3 2 1.11 1.11 0.56 5.00 7.22 4.01 490.83 490.00 1.63 24 28.85 6.44 0.13
2/CB 2 4 0.24 1.59 0.95 5.25 7.16 6.82 486.19 484.86 1.18 24 24.53 6.68 0.28
4/CB 4 5 0 1.59 0.95 5.53 7.08 6.75 484.86 484.71 0.20 24 10.11 3.45 0.36
5/CB 5 6 0.16 1.75 1.09 5.90 6.99 7.59 484.51 484.26 0.20 24 10.11 3.53 0.59
7 7 6 6.54 6.54 5.56 6.70 6.79 37.77 482.40 482.30 0.36 36 39.85 6.41 0.07
6/CB 6 8 0.19 8.48 6.80 6.49 6.85 46.57 481.80 477.23 1.76 36 88.40 12.66 0.34
8/CB 8 9 0.38 0.38 7.12 6.83 6.76 48.15 477.03 475.53 1.00 36 66.67 10.27 0.24
9/CB 9 10 0.72 1.10 7.72 7.07 6.71 51.76 475.43 475.05 0.76 36 58.13 9.29 0.09
10/CB 10 10A 0 1.10 7.72 7.16 6.69 51.60 474.95 473.70 0.66 36 54.08 8.71 0.36
10A1MH 10A 10B 0 1.10 7.72 7.52 6.60 50.96 473.60 472.60 2.36 36 102.88 14.93 0.05

17 17 18 1.23 1.23 1.14 0.00 7.22 8.20 476.95 476.25 1.00 24 22.61 6.62 0.18
19/CB 19 18 0.61 0.61 0.46 5.00 7.22 3.35 479.88 479.50 4.75 15 14.07 9.40 0.01
18/CB 18 20 0.16 2.00 1.73 5.01 7.22 12.45 476.05 475.75 0.97 24 22.25 7.29 0.07
20/MH 20 20A 0 2.00 1.73 5.09 7.20 12.46 475.55 474.55 0.96 24 22.18 7.27 0.24
20C 20C 20A 0.2 1.08 1.92 5.32 7.14 13.67 478.50 475.10 2.30 24 34.28 10.30 0.24
20A/MH 20A 20B 0 3.08 1.92 5.56 7.07 13.58 472.10 471.10 0.76 24 19.68 6.75 0.33

22/CB 21 22 0.34 0.34 0.25 5.00 7.22 1.81 476.60 474.48 2.90 15 11.00 8.28 0.15

25/CB 25 26 0.61 0.61 0.48 5.00 7.22 3.44 465.40 464.75 8.12 15 18.41 11.52 0.01
26/CB 26 27 0.34 0.95 0.74 5.01 7.22 5.37 464.55 459.70 8.98 15 19.35 13.20 0.07

29/CB 28 29 0.1 0.10 0.09 5.00 7.22 0.65 475.92 475.80 0.75 15 5.59 3.04 0.09
Page 1 of 1
HYDRAULIC GRADE LINE
May 2009
Description: Apex Peakway County: Wake Designed by: THB
Checked by: MAD

Inlet Nod
Description Total
Runoff
"Q10"
cfs Design
Pipe
Size
in
Pipe
Length
(ft) outlet ws
elevation
0.8"Do or inlet
ws elev reater Friction
Loss
Hf Contrac.
Loss
He Expan.
Loss
He Bend
Loss
Hb Total
Loss
Ht Inlet ws
Elevation Grate
Elevation elev. Diff.
to grate

1/C13 1.44 15 60 492.33 0.03 0.09 0.00 0.00 0.12 492.45 494.54 2.10

2/CB 6.82 24 113 487.02 0.10 0.24 0.46 0.00 0.80 487.82 494.23 6.41
4/CB 6.75 24 75 486.59 0.07 0.04 0.33 0.00 0.44 487.02 494.34 7.32
5/CB 7.59 24, 125 486.35 0.14 0.04 0.06 0.00 0.24 486.59 493.69 7.11

6/CB 46.57 36 260 483.74 1.27 0.61 0.17 0.35 2.39 486.13 491.63 5.50
8/CB 48.15 36 150 480.06 0.78 0.35 0.85 1.70 3.68 483.74 488.16 4.42
9/CB 51.76 36 50 479.02 0.30 0.26 0.48 0.00 1.05 480.06 487.74 7.68
10/CB 51.60 36 190 476.55 1.14 0.23 0.37 0.73 2.47 479.02 490.84 11.83
10A/MH 50.96 36 42 475.00 0.25 0.82 0.48 0.00 1.55 476.55 489.60 13.05

17 8.20 24 70 481.66 0.09 0.20 0.00 0.00 0.29 481.95 491.75 9.80
19/CB 3.35 15 8 480.84 0.02 0.51 0.28 0.00 0.81 481.66 482.88 1.23
18/CB 12.45 24 31 479.84 0.09 0.19 0.71 0.00 1.00 480.84 482.88 2.04
20/MH 12.46 24 , 104 478.51 0.32 0.19 0.27 0.55 1.33 479.84 482.88 3.04

20A/MH 13.58 24 132 472.70 0.48 0.15 0.27 0.00 0.90 473.60 487.00 13.40

22/CB 1.81 15 73 475.48 0.06 0.31 0.00 0.00 0.37 475.85 481.13 5.28

25/CB 3.44 15 8 465.75 0.02 0.87 0.00 0.00 0.90 466.65 475.36 8.72
26/CB 5.37 15 54 460.70 0.37 0.97 1.22 2.45 5.01 465.71 475.36 9.66

Page 1 of 1
BIORETENTION CELL
CALCULATIONS
Permit Number:
(to be provided by DWQ)
?oF warF9p
NCDENR Y
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
I:; PROJECT INFORMATION .
Project name Apex Peakway
Contact name Todd H. Buckner, PE
Phone number 919-755-0583
Date May 8, 2009
Drainage area number Outlet 22 1311 ovle kvi Flu t C e 1/ A
II. DESIGN INFORMATION
Site Characteristics
Drainage area 14,810 ft2
Impervious area 12,197 ft2
Percent impervious 82.4% %
Design rainfall depth 1.0 inch
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? N (Y or N)
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr peak flow ft3/sec
Post-development 1-yr, 24-hr peak flow ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SA Waters
Minimum volume required 975.0 ft3
Volume provided 989.0 ft3 OK
Storage Volume: SA Waters
1.5" runoff volume ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 1,252.0 ft2 OK
Length: 62 ft OK
Width: 20 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 6 hr OK
Drawdown time, to 24 inches below surface 18 hr OK
Drawdown time, total: 24 hr
In-situ soih.
Soil permeability in/hr
Planting media soil.
Soil permeability 2.00 in/hr OK
Soil composition
Sand (by weight) 88% OK
% Fines (by weight) 8% OK
Form SW401-Bioretention-Rev.7 Parts I and 11. Design Summary, Page 1 of 3
9/6 Organic (by weight)
Phosphorus Index (P-Index) of media
4% OK
Total: 100%
20 (unitless) OK
Permit
(to be provided by DWQ)
Form SW401-Bioretention-Rev.7 Parts I and 11. Design Summary, Page 2 of 3
Permit Number:
(to be provided by DWQ)
Basin Elevations
Temporary pool elevation
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?
Planting elevation (top of the mulch or grass sod layer)
Depth of mulch
Bottom of the planting media soil
Planting media depth
Depth of washed sand below planting media soil
463.00 fmsl
Y (Y or N) OK
N (Y or N)
462 fmsl
3 inches OK
460 fmsl
2 ft
0.25 ft
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
SHWT elevation
Distance from bottom to SHWT
Planting Plan
Number of tree species
Number of shrub species
Number of herbaceous groundcover species
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 30 feet from surface waters (50 feet if
SA waters)?
Is the BMP located at least 100 feet from water supply wells?
Are the vegetated side slopes equal to or less than 3:1?
Is the BMP located in a proposed drainage easement with access 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
Other
Y (Y or N)
3 OK
1 ft
458.75 fmsl
454 fmsl
4.75 ft OK
Y (Y or N) OK
Y (Y or N) OK
;n ft
N (Y or N) Show how flow is evenly distributed.
Y (Y or N) OK
Y (Y or N) OK
Y (Y or N) OK
Y (Y or N) OK
ft/sec
N (Y or N) OK
N (Y or N) OK
Y (Y or N) OK
#VALU E!
A
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 3 of 3
Permit No:
(to be assigned by DWQ)
III. REQUIRED ITEMS CHECKLIST
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 project. 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.
Page/ Plan
Initials Sheet No.
C9
1. Plans (1" - 50' or larger) of the entire site showing:
Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Cell dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
2. Plan details (1" = 30' or larger) for the bioretention cell showing:
Cell dimensions
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Design at ultimate build-out,
Off-site drainage (if applicable),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
Indicate the P-Index between 10 and 30
'
'
or larger) showing:
= 20
3. Section view of the bioretention cell 0
Side slopes, 3:1 or lower
Underdrain system (if applicable), and
Bioretention cell layers [ground level and slope, pre-treatment, ponding depth, mulch depth, fill media
depth, washed sand, filter fabric (or choking stone if applicable), #57 stone, underdrains (if applicable),
SHWT level(s), and overflow structure]

4. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
results of the soils report must be verified in the field by DWO, by completing & submitt ing 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). Results of soils tests of both the planting soil and the in
situ soil must include:
Soil permeability,
Soil composition (% sand, % fines, % organic), and
P-index.
"
'
or larger) prepared by a qualified individual showing:
5. A detailed planting plan (1
= 20
A variety of suitable species,
Sizes, spacing and locations of plantings,
Total quantity of each type of plant specified,
A planting detail,
The source nursery for the plants, and
Fertilizer and watering requirements to establish vegetation.

6. An assurance that the installed system will meet design specifications upon initial operation once the
project is complete and the entire drainage area is stabilized.
7. A construction sequence that shows how the bioretention cell III be protected from sediment until the
entire drainage area is stabilized. 6-ev va.?A/ A16A, _,,gkS H-?:F /c?? Irv h'c Ce (ls 1i (l i-J
to CGn$JrNCjtrf L,,,r/ III G?eG5 c>ye S/r,?/j/tt0/,
8. The supporting calculations (including underdrain calculations, if applicable).

9. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
N 10. A copy of the deed restriction.
Form SW401-Bioretention-Rev.7 Part III, Page 1 of 1
WilburSmith SUBJECT gff)re e?(?'- Cell A JOB NO. SH OF
ASSOCIATES `", d,°,?dr4BY DATE
CH. DATE
0 z? -r d' l S
Z), F) = (; 7,,
3) ?? e-' 5-, 13 0 2 - $ r1p 6 s /)/?V) de cl
Permit Number:
(to be provided by DWO)
of WATF9
AW? 00 OG
r
? > 1
NCDENR Y
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
I. 'PROJECT INFORMATION
Project name Apex Peakway
Contact name Todd H. Buckner, PE
Phone number 919-755-0583
Date May 8, 2009
Drainage area number Outlet 27 U io ?e k r, h o Cd It 13
II." DESIGN INFORMATION -
Site Characteristics
Drainage area 41,382 ft2
Impervious area 33,541 ft2
Percent impervious 81.1% %
Design rainfall depth 1.0 inch
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? N (Y or N)
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr peak flow ft3/sec
Post-development 1-yr, 24-hr peak flow ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SA Waters
Minimum volume required 2,690.0 ft3
Volume provided 2,739.0 ft3 OK
Storage Volume: SA Waters
1.5" runoff volume ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 3,084.0 ft2 OK
Length: Irregular ft OK
Width: Irregular ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 6 hr OK
Drawdown time, to 24 inches below surface 18 hr OK
Drawdown time, total: 24 hr
In-situ soil.
Soil permeability in/hr
Planting media soil.
Soil permeability 2.00 in/hr OK
Soil composition
Sand (by weight) 88% OK
Fines (by weight) 8% OK
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 1 of 3
Permit Number:
(to be provided by DWQ)
% Organic (by weight) 4% OK
Total: 100%
Phosphorus Index (P-Index) of media 20 (unitless) OK
Form SW401 -Bioretention- Rev. 7 Parts I and II. Design Summary, Page 2 of 3
Permit Number:
(to be provided by DWQ)
Basin Elevations
Temporary pool elevation 458.00 fmsl
Type of bioretention cell (answer "Y" to only one of the two following
questions):
Is this a grassed cell? Y (Y or N) OK
Is this a cell with trees/shrubs? N (Y or N)
Planting elevation (top of the mulch or grass sod layer) 457 fmsl
Depth of mulch inches
Bottom of the planting media soil 455 fmsl
Planting media depth 2 ft
Depth of washed sand below planting media soil 0.25 ft
Are underdrains being installed? Y (Y or N)
How many clean out pipes are being installed? 4 OK
What factor of safety is used for sizing the underdrains? (See

BMP Manual Section 12.3.6) 10 OK
Additional distance between the bottom of the planting media and

the bottom of the cell to account for underdrains 1 ft
Bottom of the cell required 453.75 fmsl
SHWT elevation 450 fmsl
Distance from bottom to SHWT 3.75 ft OK
Planting Plan
Number of tree species 0
Number of shrub species 0
Number of herbaceous groundcover species 1 Recommend more species.
Additional Information
Does volume in excess of the design volume bypass the

bioretention cell? Y (Y or N) OK
Does volume in excess of the design volume flow evenly distributed

through a vegetated filter? Y (Y or N) OK
What is the length of the vegetated filter? 50 ft
Does the design use a level spreader to evenly distribute flow? N (Y or N) Show how flow is evenly distributed.
Is the BMP located at least 30 feet from surface waters (50 feet if
SA waters)? Y (Y or N) OK
Is the BMP located at least 100 feet from water supply wells? Y (Y or N) OK
Are the vegetated side slopes equal to or less than 3:1? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with access to

a public Right of Way (ROW)? Y (Y or N) OK
Inlet velocity (from treatment system) 1 ft/sec OK
Is the area surrounding the cell likely to undergo development in the

future? N (Y or N) OK
Are the slopes draining to the bioretention cell greater than 20%? N (Y or N) OK
Is the drainage area permanently stabilized? Y (Y or N) OK
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 #VALUE!
Forebay
Other X
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 3 of 3
Permit No:
(to be assigned by DWQ)
JUL REQUIRED ITEMS CHECKLIST
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 project. 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.
Page/ Plan
Initials Sheet No.
1. Plans (1' - 50' or larger) of the entire site showing:
Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Cell dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
°
'
2. Plan details (1
= 30
or larger) for the bioretention cell showing:
Cell dimensions
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Design at ultimate build-out,
Off-site drainage (if applicable),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
Indicate the P-Index between 10 and 30
26 3. Section view of the bioretention cell 0' = 20' or larger) showing:
Side slopes, 3:1 or lower
Underdrain system (if applicable), and
Bioretention cell layers [ground level and slope, pre-treatment, ponding depth, mulch depth, fill media
depth, washed sand, filter fabric (or choking stone if applicable), #57 stone, underdrains (if applicable),
SHWT level(s), and overflow structure)
LL J,
4. A soils report that is 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). Results of soils tests of both the planting soil and the in
situ soil must include:
Soil permeability,
Soil composition (% sand, % fines, % organic), and
P-index.
"
'
5. A detailed planting plan (1
= 20
or larger) prepared by a qualified individual showing:
A variety of suitable species,
Sizes, spacing and locations of plantings,
Total quantity of each type of plant specified,
A planting detail,
The source nursery for the plants, and
Fertilizer and watering requirements to establish vegetation.
l /
6. An assurance that the installed system will meet design specifications upon initial operation once the
project is complete and the entire drainage area is stabilized.

7. A construction sequence that shows how the bioretention cell will be protected from sediment until the
entire drainage area is stabilized. 6e Y t r:4l +/c ,k s J"ks µ ti F b i ot?? l er h?; , Ce l l S irJ01 t,"
?j? be Gu ?s{r?c! ecQ u?Nl All GreGs ay-e SF,W(IeA
8
Th
.
e supporting calculations (including underdrain calculations, if applicable).

9. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
10
A copy of the deed restriction
.
.
Form SW401-Bioretention-Rev.7 Part III, Page 1 of 1
Permit Number:
(to be provided by DWQ)
?? ??? vJAr?gO
r•? ? v
r
mi
HCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
L,R"WACTINFORMATION'
Project name Apex Peakway
Contact name Todd H. Buckner, PE
Phone number 919-755-0583
Date May 11, 2009
Drainage area number Outlet 29 Q? o ??(?,,? Ia oI j t i
II DESIGN INFORMATION"
Site Characteristics
Drainage area 4,356 ft2
Impervious area 4,356 ft2
Percent impervious 100.0% %
Design rainfall depth 1.0 inch
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? N (Y or N)
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity in/hr
Pre-development 1-yr, 24-hr peak flow ft3/sec
Post-development 1-yr, 24-hr peak flow ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume: Non-SA Waters
Minimum volume required 51.0 ft3
Volume provided 125.0 ft3
Storage Volume: SA Waters
OK
1.5" runoff volume ft3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 196.0 ft2 OK
Length: 20 ft OK
Width: 10 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 6 hr OK
Drawdown time, to 24 inches below surface 18 hr OK
Drawdown time, total: 24 hr
In-situ soil:
Soil permeability in/hr
Planting media soil:
Soil permeability 2.00 in/hr OK
Soil composition
% Sand (by weight) 88% OK
% Fines (by weight) 8% OK
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 1 of 3
Permit Number:
(to be provided by DWQ)
% Organic (by weight) 4% OK
Total: 100%
Phosphorus Index (P-Index) of media
20 (unitless) OK
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 2 of 3
Permit Number:
(to be provided by DWQ)
Basin Elevations
Temporary pool elevation 469.00 fmsl
Type of bioretention cell (answer "Y" to only one of the two following
questions):
Is this a grassed cell? Y (Y or N) OK
Is this a cell with trees/shrubs? N (Y or N)
Planting elevation (top of the mulch or grass sod layer) 468 fmsl
Depth of mulch inches
Bottom of the planting media soil 466 fmsl
Planting media depth 2 ft
Depth of washed sand below planting media soil 0.25 ft
Are underdrains being installed? Y (Y or N)
How many clean out pipes are being installed? 1 OK
What factor of safety is used for sizing the underdrains? (See 10 OK
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and 1 ft
the bottom of the cell to account for underdrains
Bottom of the cell required 464.75 fmsl
SHWT elevation 462 fmsl
Distance from bottom to SHWT 2.75 ft OK
Planting Plan
Number of tree species 0
Number of shrub species 0
Number of herbaceous groundcover species 1 Recommend more species.
Additional Information
Does volume in excess of the design volume bypass the

bioretention cell? Y (Y or N) OK
Does volume in excess of the design volume flow evenly distributed

through a vegetated filter? Y (Y or N) OK
What is the length of the vegetated filter? 50 ft
Does the design use a level spreader to evenly distribute flow? N (Y or N) Show how flow is evenly distributed.
Is the BMP located at least 30 feet from surface waters (50 feet if

SA waters)? Y (Y or N) OK
Is the BMP located at least 100 feet from water supply wells? Y (Y or N) OK
Are the vegetated side slopes equal to or less than 3:1? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with access to

a public Right of Way (ROW)? Y (Y or N) OK
Inlet velocity (from treatment system) 1 ft/sec OK
Is the area surrounding the cell likely to undergo development in the

future? N Y or N)
( ) OK
Are the slopes draining to the bioretention cell greater than 20%? N (Y or N) OK
Is the drainage area permanently stabilized? Y (Y or N) OK
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 #VALUE!
Forebay
Other Y
Form SW401-Bioretention-Rev.7 Parts I and II. Design Summary, Page 3 of 3
Permit No:
(to be assigned by DWQ)
III. REQUIREf)ITEMSOECKLIST ,
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 project. 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.
Page/ Plan
Initials Sheet No.
Zl? 1. Plans (1 ° - 50' or larger) of the entire site showing:
Design at ultimate build-out,
Off-site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Cell dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
2. Plan details (1" = 30' or larger) for the bioretention cell showing:
Cell dimensions
Pretreatment system,
High flow bypass system,
Maintenance access,
Recorded drainage easement and public right of way (ROW),
Design at ultimate build-out,
Off-site drainage (if applicable),
Clean out pipe locations,
Overflow device, and
Boundaries of drainage easement.
Indicate the P-Index between 10 and 30
G? 3. Section view of the bioretention cell (120' or larger) showing:
Side slopes, 3:1 or lower
Underdrain system (if applicable), and
Bioretention cell layers [ground level and slope, pre-treatment, ponding depth, mulch depth, fill media
depth, washed sand, filter fabric (or choking stone if applicable), #57 stone, underdrains (if applicable),
SHWT level(s), and overflow structure]
_
4. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
results of the soils report must be verified in the field by DWO, 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). Results of soils tests of both the planting soil and the in
situ soil must include:
Soil permeability,
Soil composition (% sand, % fines, % organic), and
P-index.
"
'
5. A detailed planting plan (1
= 20
or larger) prepared by a qualified individual showing:
A variety of suitable species,
Sizes, spacing and locations of plantings,
Total quantity of each type of plant specified,
A planting detail,
The source nursery for the plants, and
Fertilizer and watering requirements to establish vegetation.

6. An assurance that the installed system will meet design specifications upon initial operation once the
project is complete and the entire drainage area is stabilized.
L, 7. A construction sequence that shows how the bioret?enntion cell will be protected from sediment until the
G
I N
?
/i
k
e rziw
L S
-c F )4-le Ce
s
trl
entire drainage area is stabilized.
S 1
?1 v tnv? ?e GunS??i, ckcf o„?lr' X'1I G.'PGS ti.r S]xbi?i ZecP,
- 8. The supporting calculations (including underdrain calculations, if applicable).
?
` 9. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
/
./ 10. A copy of the deed restriction.
Form SW401-Bioretention-Rev.7 Part III, Page 1 of 1
SUBJECT ?1? ?G?h{ Io.. f Czll C JOB NO. SH OF
WilburSmith .?U BY DATE
A S S O C I A T E S
CH. DATE
La :? ?? 1+ ??G?"5
i
z - (+ ricer,

/-411 /-re-,