20070666 Ver 2_More Info Received_20080320

C ENGINEERING
March 20, 2008
Ms. Cyndi Karoly, Supervisor
NC Department of Environment and Natural Resources
401 Oversight/Express Review Permitting Unit
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604
RE: Oak Forest Road Extension
Ut to Perry Creek [030402, 27-25-(2), C, NSW]
Dear Ms. Karoly:
~~- ot~ ~t~ v z
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MPR ~
os ~ °s~~~
Enclosed is one (1) full-sized revised set of plans and seven (7) sets of the permit package
for Broughton Properties Subdivision/Oak Forest Road Extension, for your review based
on your review comments dated February 19, 2008. The responses to your comments are
as follows:
Comment 1 a and b: One of the filter strips in question has been replaced with a terraced
bioretention basin.
Comment 1 c: Level spreader has been re-designed and brought into conformance.
Comment 2: Level spreader and Bio-retention forms have been completed and are
enclosed. A photograph is not available since the filter strip is designed to be graded out
of the slope to conform to the filter strip detail.
Comment 3: Form has been prepared and included
Comment 5: Bio-retention areas have been designed and footprints shown on the plans
See BMP spread sheet for design and overall plan sheet.
Should you have any questions or need any additional information, please do not hesitate
to contact me or Mary Jo Lee at 788-0224.
Sincer~y,
. ~.~ y ~ ''
r'~`'~'l ____..._._........
Tom Heeler, PE
Cc: Ed Bailey
^ PO Box 30128, Raleigh, NC 27622 • rE~ 919.788.0224 • Fax [phone]

~p~ ~ A rFj~Q Michael F. Easley, Governor
,~ G' William G. Ross Jr., Secretary
~ North Carolina Department of Environment and Natural Resources
~ ~ ~
Q ~ ~`"~~' ~ Coleen H. Sullins, Director
Division of Water Quality
.,e~~~`
February 19, 2008
DWQ Project # 07-0666, Ver. 2
Wake County
CERTIFIED MAIL: RETURN RECEIPT REQUESTED
Broughton Properties
P.O. Box 464
Raleigh, NC 272602
Subject Property: Oak Forest Road Extension ®~~ ~ a~~ D
Ut to Perry Creek [030402, 27-25-(2), C, NSW] -
MAR 2, 0 ? ~~?8
REQUEST FOR MORE INFORMATION
DENk•YVr~ir~..~r~.' ;''
yYfTLANDS AND STUtZMWIIIEit 4sKrU'+€a,
Dear Sir or Madam:
On November 9, 2007, the Division of Water Quality (DWQ) received your application dated November
8, 2007 to impact 137 linear feet of perennial stream and 7,486 square feet of Zone 1 Neuse River basin
protected riparian buffer and 4,297 square feet of Zone 2 Neuse River basin protected riparian buffer to
construct the proposed mixed-use development at the site. On January 10, 2008, January 15, 2008, and
January 17, 2008, the DWQ received additional information from you, however, the DWQ has
determined that your application remains incomplete and/or provided inaccurate information as discussed
below. The DWQ will require additional information in order to process your application to impact
protected wetlands and/or streams on the subject property. Therefore, unless we receive five copies of the
additional information requested below, we will have to move toward denial of your application as
required by 15A NCAC 2H .0506 and will place this project on hold as incomplete until we receive this
additional information. Please provide the following information so that we may continue to review your
project. ,
Additional Information Requested:
Please address the following issues with the level spreader design:
a. The plan sheets show that the filter strips downslope of both proposed level spreaders
significantly exceed eight percent. The construction sequence states that the filter strip
slopes will be verified as part of the construction process. In fact, filter strip slopes must
be determined as part of the design process. If the level spreaders cannot be re-located to
an area with appropriate filter strip slopes, then they will have to be replaced by a BMP
that removes a minimum of 85 percent TSS and 30 percent of the TN and TP from the
entire drainage area.
b. The filter strip associated with level spreader 1 is only 40 feet in width. A minimum
width of 50 feet is required.
c. The plan views of the level spreaders do not appear to comply with the DWQ BMP
Manual -the forebays appear to be located too far away from the level lips.
2. If you are able to address the above issues associated with the level spreader designs such that
they comply with the DWQ BMP Manual, then you must provide ALL of the information
NorthCarolina
401 Oversight/Express Review Permitting Unit ~/vLIt611'll~~f
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone] /FAX [phone] /Internet: http:%; h2o.enrstate.nc.usincwetlancis
An Equal Opportunity/Affirmative Action Employer - 50% Recycled/10% Post Consumer Paper

Broughton Properties
Page 2 of 2
February 19, 2008
requested in the Required Items Checklist (or your application will be returned). Your submittal
failed to provide the following items:
a. Plan details for the level spreader at 1" = 30' or larger.
b. Adate-stamped photograph of the vegetation in the filter strip.
c. The supporting calculations for the te, which you appear to have assumed is 10 minutes
without providing documentation for this decision.
d. A formally signed and notarized Inspection and Maintenance Agreement for the level
spreaders.
3. If another BMP is used in place of the level spreaders, then you must provide the appropriate
BMP Supplement Form (with both the Design Summary and Required Items Checklist
completely filled out) and ALL required items attached. Failure to provide the complete form
and ALL of the required items will result in a return of application.
4. If possible, please use the interactive feature on the BMP Supplement Forms to aid in your design
and our review.
5. More information will be needed before the DWQ will approve the conceptual stormwater plan.
The bioretention areas must be sized based on current assumptions about the percentage
impervious surface in each contributing drainage area. Then, these bioretention area footprints
must be shown to scale on the site plan.
Please submit this information within 30 calendar days of the date of this letter. If we do not receive this
requested information within 30 calendar days of the date of this letter, your project will be withdrawn
and you will need to reapply with a new application and a new fee.
This letter only addresses the application review and does not authorize any impacts to wetlands, waters
or protected buffers. Please be aware that any impacts requested within your application are not
authorized (at this time) by the DWQ. Please call Ms. Cyndi Karoly or Mr. Ian McMillan at 919-733-
1786 if you have any questions regarding or would like to set up a meeting to discuss this matter.
Sincerely,
Cyndi Karoly, Supervisor
401 Oversight/Express Review Permitting Unit
CBK/~m
cc: Lauren Witherspoon, DWQ Raleigh Regional Office
USACE Raleigh Regulatory Field Office
File Copy
Central Files
CH Engineering/Maha Chambliss, P.O. Box 30128, Raleigh, NC 27622
070666V er20akForestRoadExt(W ake)On_Hold

Permit Number:
' (to be provided by DWQ)
~~F WATE9Q
O T
NC~ENft
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 IIIJ must be printed, filled out and submitted along with all of the required information.
II: PR"QJECT°INFORM'A~IQNr, >f,`'`µ r+s -r ~- ~~ '~' -
Project name ~~~ i-a~s't• ~R{J" . ~~ ~ ~F_t~t~ls
Contact name ~ hna~-`i~ s ~~E P~.f~;2
Phone number ~; ~ - -~~ ~, - ~ ~ ~„.i..
Date ~ ~ ! ~' ~~ G`
Drainage area number ~~„ c ~ m,~-:-
'-° -~
r
~~~.:~~'r•~, I.~u4..)C': '~..d•~:• ~.-'~'F"!i ~r~IC=,t~ .^'•~'. mss'`'" i
I1:~QESIGN9INF~;RM~TI;ON ~ :r'. + ,-•+.~ s~~"r' ~~~' t~'~ ~ ~`:f,~ -a«x~ , ~:f9 `'-~ . ,~:~.~f`-~n`. _
Site Characteristics I~o~-~~4'~~~'` ' ~-~~T~~= f'=~,'
,..
Drainage area ~^r, ~ 'Pry ftZ .~ = ` ~-`
r
Impervious area; ~, ~:.,?`~~~ ft2 ----
Percent impervious ~ ~~~ % ;F~? !~ ~,~~~~'~''•
Design rainfall depth ;~ inch ~~'t.; ~- .~ ~`~~ ~. ' ' ~: ,
Peak Flow Calculations
Is pre/post control of the 1-yr, 24-hr peak flow required? _ _}'`~ (Y or N) Imo,
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-SR Waters
Design volume ,=~ ti ft3 Ic`-~j- i- .~~' -(-oT~V~ *~r~,,Cj,.~
Storage Volume: SR Waters
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 r~~,, •f

~ ~ ^,.~;;,~, ~

~ ,... , ,
r_" _.`
Ponding depth of water ;l~
inches ; ~` ` ,. ~„_
Ponding depth of water 0.00 ft
Surface area of the top of the bioretention cell ~ Sd ft2 J~ %~ ~;~~~,~,,~
Length: ~~` ~ ~ ~ ~

-or- Radius ft
Soils Report Summary
Drawdown time, ponded volume ~ ~ hr ~ ~.
Drawdown time, to 24 inches below surface ~j.°,,- _ , hr ~`~~~~" ~ ~"`'~ ~~%G ~ ~/D ` `~ ~ `""
Drawdown time, total: ~~ 0 hr , ,~. ~ ~ ~ ~ C
In-situ sail:
Soil permeability ~,~~ in/hr ~,
Planting media soil: ~_
Soil permeability ~ , ~ in/hr
Soil composition
Sand (by weight) °~,,,;`
Fines (by weight) ! Z~
Form SW401-Bioretention-Rev.2 Parts I and 11. Design Summary, Page 1 of 2

Permit Number:
(to be provided by DWQ)
Organic (by weight) Flo
Total: ~ o~ 0%
Phosphorus Index (P-Index) ~~ - ~~ (unitless)
Basin Elevations C '~ c...~':', ~ j G2~~-C.. ~-- GE<t~~ Z ~~-~.
Temporary pool elevation 2 g`~, ~ fmsl Z ~ ~},, ~ 282 , ~
Planting elevation (top of the mulch) 2 ~,~. ~ fmsl ~~ , ~/ 2g/, O
Bottom of the cell ~ ~_~ , ~ fmsl G ~p ;~ 2 ~ J. ~
Planting depth ?, y O ft ~- y~ ~ ~
~
Depth of mulch ~. inches ~ ~
~~tr~~ ~ ,:.~,r~~
SHWT elevation 2~ -> fmsl ~'`' ~', ~'j ~' ~%~ ~
Are underdrains being installed? ~ (Y or N)
How many clean out pipes are being installed? ~7b~ ~ , ~ ~' (? I '~ rc n~u.' - }~~'~' `'~/
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 0 ft
the bottom of the cell to account for underdrains
Bottom of the cell required 7 0,=,, ~ 0 fmsl
Distance from bottom to SHWT ~,~, 0 ft
Type of bioretention cell (answer "Y" to only one of the two
following questions):
Is this a grassed cell? _ ~ (Y or N)
Is this a cell with trees/shrubs? l,,j.: (Y or N)
Planting Plan
Number of tree species ,I,;,F~`~,
Number of shrub species z~ ~/,.
Number of herbaceous groundcover species
Additional Information
Does volume in excess of the design volume bypass the (Y or N)
bioretention cell?
Does volume in excess of the design volume flow evenly (Y or N)
~
distributed through a vegetated filter? `~; ,
What is the length of the vegetated filter? y rJ- ft
Does the design use a level spreader to evenly distribute flow? P` (Y or N)
Is the BMP located at least 30 feet from surface waters (50 feet if Y or N
( )
SA waters)? `~
Is the BMP localed at least 100 feet from water supply wells? '~ (Y or N)
Are the vegetated side slopes equal to or less than 3:1? ~(, (Y or N)
Is the BMP located in a recorded drainage easement with a (Y or N)
recorded access easement to a public Right of Way (ROW}? ~
Inlet velocity (from treatment system) 2, C~ ft/sec
Is the area surrounding the cell likely to undergo development in
future?
th ~ Y or N
( )
e
Are the slopes draining to the bioretention cell greater than 20%? ~ (Y or N)
f'~
Is the drainage area permanently stabilized? '~ (Y or N)
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
Form SW401-Bioretention-Rev.2 Parts I and II. Design Summary, Page 2 of 2

Permit No:
(to be assigned by DWO)
III. ~REQU-REI?r1TsEMS~CI~ECKLlS.T, _ - _
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request far 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
Ini ials Sheet No.
~- ~ 1. Plans {i" - 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.
F
~"' ~
3. Section view of the bioretention cell (1" = 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] '
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
A - P-index.
j~ ~ 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,
~~~ ~ ~r t:,.:r L^ -Total quantity of each type of plant specified,
- A planting detail,
-The source nursery for the plants, and
,I -Fertilizer and watering requirements to establish vegetation.
~_!
~ 6. An assurance that the installed system will meet design specifications upon initial operation once the
/„ J,
~/
~
~ 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.
8. The supporting calculations (including underdrain calculations, if applicable).
/
~ 9. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
1~ '~_ ~pvcp~~ ~ 7 ~~:! R:iD!tt;~ ta~.~10. A copy of the deed restriction.
~c.?~-
Form SW401-Bioretention-Rev.2 Part III; Page 1 of ~

ENGINEERING CALCULAT!®N SHEET PAGE OF
CLIENT ~. ~f ~~~e t SUBJECT Rio:.>~-.~~-c,F.~ -- ~/~a.? F~~~-.~°-z ~%r Prepared By ~-~ Date ~'!'~=F~''#-
PROJECT No. Reviewed By Date

~~
NCDENR
o~oF wnrF9oG
O~~,c
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111J must be printed, filled out and submitted along with all of the required information
I. PROaECT'>INFORMAT[ON° ,' _ _ ",:. °,.~ . `;, ::,;; ~~-.`. ~ ,<,.,: `I
Project name ~a~ ~rjeGg-~' l~2«t~ ~,Gfw.,S~,~
Contact name --~c~ Lc~. C - nl ~ /NCB; 2f/VCr
Phone number ~ _ L
Date rj fq /p~
Drainage area number Z
~II..~DESIGN~INFORM"ATION , ~ ,, Y :, ran ,"`E ~ . ~~-:,~ ~ ",,_~~ --~
- -
For Level Spreaders Receiving flow From a BMP
Type of 8MP /1~//~
Drawdown flow from the BMP r//ti cfs
For Level Spreaders Receiving Flow from the Drainage Area
Drainage area ~~~ft2 ~/. Z9f AG .
Impervious surface area ~
ft2
Percent impervious ?4 v
,
Rational C coefficient , 8 ~ $ S
Peak flow from the 1 in/hr storm /, p s' cfs
Time of concentration /p min
Rainfall intensity, 10-yr storm ~ ~ f'
in/hr
Peak flow from the 10-yr storm _
_
~. 93 _cfs
Where Does the Level Spreader Discharge?
To a bioretention cell? /~/ (Y or N)
To a wetland? n/ (Y or N)
To a filter strip or riparian buffer? Y (Y or N)
Other (specify)
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass ~,~y ft
Width of dense ground cover ft
Width of wooded vegetation ft
Total width ,~~ ft
Slope (from level lip to to top of bank) ~
Are any draws present? /~ f (Y or N)
Level Spreader Design
Forebay surface area Qp sq ft
Feet of level lip needed per cfs (a. 29. eF Ow.~. Jrri, ~ /~ fUcfs
Answer "Y" to one of the following:
Length based on the 1 inlhr storm? ~/ (Y or N)
Length based on the 10-yr, 24-hr storm? ~ (Y or N)
Length based on the BMP discharge rate? _~ j _ (Y or N)
Design flow rf', !f3
cfs
Is a bypass device provided? _
~ (Y or N)
Length of the level lip /Oft
Are level spreaders in series? ~(,( (Y, or N)
y~
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Parts I. and II. Design Summary, page 1 of 2

III: RE'Q'U1RED'1TEMS=CHECKLIST ~- a;~ , ~ ~ ~., -~
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
Ini
tials Sheet No.
~
~
-~-7i ~P- I ~P-Z 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),
-Forebay (if applicable),
- High flow bypass system,
- Maintenance access,
-Recorded drainage easement and public right of way (ROW), and
- Boundaries of drainage easement.
~~~( ~p' ~' 2. Plan details (1" = 30' or larger) for the level spreader showing:
- Forebay (if applicable),
-High flow bypass system,
-One foot topo lines between the level lip and top of stream bank,
-Recorded drainage easement, and
-Design at ultimate build-out.
-J,
~-df 3. Section view of the level spreader (1" = 20' or larger) showing:
- Underdrain system (if applicable),
- Level lip,
- Upslope channel, and
- Downslope filter fabric.
N I~ 4. Adate-stamped photograph of the filter strip~that clearly shows the type of vegetation that Is present
~o Sr
i~~~~ a G ~ !^~5. An assurance that the installed system will meet design specifications upon initial operation once the
ce.J~f a°`'s project is complete and the entire drainage area is stabilized.
~~ ~ %~ ~-~f~A 6. A construction sequence that shows how the level spreader will be protected from sediment until the entire
drainage area is stabilized.

1~.
~ `~- z
C~.-G. s
7. The supporting calculations.
_~~'._ -t= ~'`t'ffl 8. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
~ ~_ 9. A copy of the deed restriction.

Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Part III, page 1 of 1

ENGINEERING CALCULATION SHEET
CLIENT SUBJECT Prepared By
PROJECT NO. ~~ ~~ ,~ ~-t~ Reviewed By
~~~~e~~ ~'-~f- -~ ,~ - ~,. nom.
,~' 4.:~ ~ '~: ~ ~s ci -
ta.
PAGE __ OF
Date
Date
~, ~'
. _ ~,~,
~7 c~ ~)
GJ 4 ': r
~~ ~~~

ENGINEERING CALCl1LAT!®~i SI-O~~T' PAGE W OFD
s
CLIENT SUBJECT 5v f f u~-- ~ ~~ ~ ^.~-~.c.~,. c..t.~---~.~~ ~ 6 Prepared By ~ ~ Date ~ ~! ° ~ 6 u'~
PROJECT No. ~~ ~.- !=:4 r.=- ~-;.~'° ~--`*~- << -~~ f' Reviewed By Date
,-v,f- ~.a ~-_ r -~
u

p:..
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i t

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i S8 dig e . ~G:~, ~
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~'

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t"G` -=-^;r~,•., s:-,~. '~~ ~nh; ~~ ~ ~.~t' v~ ~~ ~r ~i' r~ F ~>' "° ~~ ~"~ f U. fir` R •~;..t'"-! `j ~

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4P~ ~~~~
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Preliminar Bioretention Area Cal cs for Brou hton Pro erties, LLC
Site Area Assumed Imp. Rv WQV (cf) Depth(inches)
S-1 57,890 60% 0.59 2846 12
S-2 44,115 60% 0.59 2169 12
S-3 62,160 60% 0.59 3056 12
S-4 30,147 60% 0.59 1482 12
S-5 82,057 60% 0.59 4034 12
S-6 118,743 60% 0.59 5838 12
S-7 168,206 60% 0.59 8270 12
S-8 240,200 60% 0.59 11810 12
Basin Area L W
2846 71 40
2169 62 35
3056 70 44
1482 50 30
4034 100 40
5838 100 58
8270 120 69
11810 135 30
4050
~
80 _
60 4800
90 22 1980 ~
70 14 980 ~
11810

Added Designs

I ~~~~ L~
'~~
__,~~
"`~
~J~~~Ir~m ~- ~~~~
A ~~r r~.~ ~~1
~~~~ ~ ~~.
Ind ~~+~~ ~~
~w, ~
r~ ~-~;:
i -~
,. ~,
~f`~r
_~~.~ ~~;~ ~~. ~s _
~~r~~
~nr~ ~r~~
BMP Manual Figure ~-2
adapted from Hathaway 2006

NCDENR Stormwater BMP Manual
Chapter Revised 09-28-07
the volume attainment requirements. As for all bioretention designs, the diversion
method must meet all of the Major Design Elements.
Figure 12-3c
Parking Edge and Perimeter with Curb
Prince George's County (2000a)
~\~
\~~
~~
Bioretention Area Limit .,..- `\~~
..•r- !~ Grass Swale ~'~ Limit oP
Distrubance
/ -~~,ya-,-`_. ~`~~ ~r~,~"~~,J~„~ '~ ~~ Existing Inlet
~._ may; y
=-~>.~`y~` ~;w ~ -:jai
Existing Curb ~ ~•-
~ --
.,~':
inlet Dettec#ors
ExistingPavement~"..•• •-.•_.°:.;-;.„:::;•::;•::~::.•~~•:~::~:~~"'--~:.~•..•:`'iclaw wifhCurbOpening
(See Appendix A)
Bioretention Cells on Steep Slopes
Figure 12-3d depicts a bioretention terrace that can be used in sloping terrain (for 10-20%
slopes). An impermeable or very low permeability geomembrane must be used against
the gabions or similar retaining structure to prevent flow from leaving the treatment
unit through that surface. An underdrain could be placed at the low point of the filter if
the native soil that the unit is built against will not provide adequate infiltration
capacity.
Figure 12-3d
Bioretention Terrace Suitable for Use on Slopes 10-20%
Gabion Bioretention Plants
1 1 1 ~1 1 I
I.JI S .
J~--
.: ~ ,n ~ ~ ,~;•R `-" 1' Sand and Top
~ K nr~ .r : fi
Soil Mix
5.0'
I 2' Sand
v,J~ Geotextile
Bioretention 12-9 July 2007

LEVEL SPREADER CONSTRUCTION SEQUENCE
1. PRIOR TO CONSTRUCTION OF THE LEVEL SPREADER,
CONTRACTOR TO VERIFY THAT GROUND CONTOURS ARE
PARALLEL TO THE LEVEL SPREADER LOCATION AS SHOWN ON
THE PLANS, SLOPES ARE LESS THAN 6 TO 8 PERCENT, AND THAT
NO DRAWS ARE LOCATED IN THE FILTER STRIP ADJACENT TO THE
LEVEL SPREADER. ALSO, CONTRACTOR SHALL VERIFY THAT THE
LEVEL SPREADER IS 50 FEET AWAY FROM THE STREAM IF IT IS
BEING INSTALLED IN AN AREA COVERED BY A RIPARIAN AREA
PROTECTION RULE.
2. PRIOR TO INSTALLATION OF THE LEVEL SPREADER, THE
VEGETATION OF THE FILTER STRIP SHALL BE ASSESSED BY THE
CONTRACTOR AS DENSELY VEGETATED OTHERWISE ADDITIONAL
PLANTINGS WILL NEED TO BE ADDED PRIOR TO THE
.INSTALLLATION. IF GRASS COVER NEEDS TO BE RE-ESTABLISHED
IN THE FILTER STRIP, CONSTRUCTION MAY BE LIMITED TO THE
GROWING SEASON.
3. CONTRACTOR IS TO MAKE BEST EFFORTS TO ENSURE THAT THE
LEVEL SPREADER IS ACTUALLY LEVEL TO ENSURE A UNIFORM
DISTRIBUTION OF FLOW. THE LEVEL SPREADER SHALL BE
CONSTRUCTED ON MATERIAL COMPACTED TO 95% OF STANDARD
PROCTOR TEST LEVELS PRIOR TO SEEDING FOR THAT AREA NOT
CONSIDERED THE SEEDBED.
4. CONTRACTOR TO ENSURE THAT THE LEVEL SPREADER AND
FILTER STRIP ARE PROTECTED FROM SEDIMENT AND
STORMWATER FLOWS DURING CONSTRUCTION. A TEMPORARY
STORMWATER DIVERSION SHALL BE NECESSARY UNTIL THE
LEVEL SPREADER HAS FULLY STABILIZED.

C lF' 1
INSPECTION AND MAINTENANCE AGREEMENT
Project: c;rP~,L i%r~,~~4T ~~ ~~r
STORMWATER CONTROL STRUCTURE
LEVEL SPREADER/FILTER STRIP AREA
Raleigh, N.C.
Owners: O~ c>r ~' ~a~ aD~i'~~tl~y,~
Address: .l~. L Z~~Z
Phone Number:
Prepared by: ~~Ft~GitBF_t.~I'clG, !~i t..~.
Date: 3~z' ~loB
Project: Ds¢,C r~a~~sT ~ ~~~
Date Constructed: ~~ ~
Location: Written description of device location site; reduced site plan showing location
of device; longitude and latitude of device and lot number on the recorded subdivision
,plat. Reduced detail of device showing all pertinent information including but not limited
to dimensions and associated elevations.
~,
Receiving Water Course: °,~;.E':.~:'.-~c'° ~rr'~r~
Contractor: (List below)
Landscape Contractor
i ~,~
Grading Contractor
i,~,~
OPERATIONS AND MAINTENANCE AGREEMENT
[PROJECT NAME] STORMWATER LEVEL SPREADER/FILTER STRIP AREA
This agreement establishes procedures for maintenance and operation of the [project
name] level spreader/filter strip area (s) in accordance with the City of Raleigh
guidelines.
MAINTENANCE OF LEVEL SPREADERS
Vegetation-The drainage areas have a ground cover of warm season grasses or
fescue, which if properly maintained will prevent erosion of the embankment and

provide an easy surface for inspection. The grass will be most difficult to obtain in the
area subject to water level fluctuation. Grass should be fertilized every October and
April.
Re-Seeding-Periodic re-seeding may be required to establish grass on areas where
seed did not take or have been destroyed. Before seeding, fertilizer (12-12-12) should
be applied at a minimum rate of 12 to 15 pounds per 1,000 SF. The seed should be
evenly sown at a rate of three pounds per 1,000 SF. The seed should be covered with
soil to the depth of approximately ~/a". Immediately following the planting, the area
should be mulched with straw.
Trees and Shrubs-Trees, shrubs and other landscape vegetation should~be permitted
only as shown on the approved planting plan. The vegetation should be kept healthy
and vibrant. If a tree or shrub dies it should be removed and replaced with another tree
or shrub from the same species (see attached maintenance schedule).
Mowing-Grass mowing, brush cutting and removal of weed vegetation will be
necessary for the proper maintenance of the areas. All area slopes and vegetation
should be mowed when the grass exceeds 8" in height to a minimum height of three (3")
inches. Acceptable methods include the use of weed whips or power brush cutters and
mowers.
Erosion-Erosion occurs when the water concentrates causing failure of the vegetation
or when vegetation dies and sets up the environment for rill erosion and eventually
gullies from the stormwater runoff. The areas should be inspected. Proper care of
vegetative areas that develop erosion is required to prevent more serious damage to
the site. Rills and gullies should be filled with suitable soil compacted and then seeded.
Methods described earlier on vegetation should be used to properly establish the grass
surface. Where eroded areas are detected, the cause of the erosion should be
addressed to prevent a continued maintenance problem. Frequently, problems result
from the concentration of runoff to one point of the bio-retention area instead of a
uniform distribution of runoff. This can be corrected by reshaping, to more evenly
distribute the runoff to areas not experiencing erosion problems.
Rodent Control-Generally in this urban environment, rodents are not a problem.
Rodents such as groundhogs, muskrats and moles are attracted to moist, wet areas
and can be quite dangerous to structural integrity and proper performance of the
earthwork and drainage. Groundhogs and muskrats thrive on burrowing into the
manmade earthwork, which become pathways for seepage. In the event that burrows
are detected within the level spreader/filter strip area, the rodents should be dealt with
by removal.
Trash and Debris--Trash acts as a barrier to stormwater infiltration and attracts
unwanted pests. The level spreader/filter strip area should be kept clear of debris such
as loose bottles, cans, food containers and other forms of rubbish. The area should be
cleared of debris as needed, but no less than twice a year.
Sedimentation & Dredging-

Filter strips that receive excessive sediment may require periodic regrading and
reseeding of their upslope edge because deposited sediment can kill grass and
change the elevation of the edge such that the stormwater no longer flows through
the strip in thin sheets. The frequency of this sediment removal can be reduced by
ensuring that the areas around the level spreader are stabilized with a vegetative
ground cover. This would include a periodic application of fertilizer and/or other
treatments necessary to promote a stable ground cover. The sediment must be
removed and the original filter strip restored
The sediment should be hauled offsite to a suitable landfill site or mounded on site
with slopes no greater than 3:1 and stabilized with approved ground cover. This
sediment site must be away from streams and/or any permanently protected open
space areas.
OPERATION
After filter strip is established, it will be inspected quarterly and within 24 hours after
every storm event greater than 1.0 inch. Record Keeping--Operation of level
spreader/filter strip area should include recording of the following:
Annual Inspection Reports--A collection of written inspection reports should be
kept on record in Section IV of this manual. Inspection should be conducted
annually. Copies should be provided to the City of Raleigh stormwater
Management Section of the Engineering Department.
Observations--All observations should be recorded. Where periodic inspections
are performed following significant rainfall, these inspections should be logged
into the Periodic Inspection, Operations and Maintenance Form in Section IV of
this manual.
Maintenance--Written records of maintenance and/or repairs should be recorded
on the Periodic Inspection, Operation and Maintenance Form in Section IV of this
manual.
Other Operational Procedures--The owner should maintain a complete and up-to-date
set of plans (as-built drawings) and all changes made to the level spreader./filter strip
area over time should be recorded on the as-builts.
Example Maintenance Schedule for Level Spreader/Filter Strip Areas
Descri tion Method Fre uenc Time of ear
FILTER STRIP
Reseed to maintain a dense Mechanical Yearly All year
Growth of ve etation or B hand
Stabilize groundcover in the By hand As needed As needed
drainage area to reduce the
sediment load to the
ve etation.

Mow grass filter strips and Mechanical 2-3 times a All year
the clippings harvested to year
promote the growth of thick
vegetation with optimum
pollutant removal efficiency.
Turf grass should not be cut
shorter than 3 to 5 inches
and may be allowed to grow
as tall as 12 inches
depending on aesthetic
requirements. Forested
filter strips do not require
this kind of maintenance.
Soil to be aerated Mechanical Once a ear As needed
Soil pH will be tested and Mechanical Once a year Lime added as
lime will be added if needed as a result of
necessa H test all ear
Check for trash/debris and By hand As needed As needed
remove .
Areas of bare soil and/or Mechanical As needed As needed
erosive gullies have formed.
Regrade: the soil if
necessary to remove the
gully, and then plant a
ground cover and water until
it is established. Provide
lime and aone-time fertilizer
application.
Sediment is building up on Mechanical As needed As needed
the filter strip. Remove the or By hand
sediment and restabilize the
soil with vegetation if
necessary. Provide lime and
a one-time fertilizer
a lication.
Plants are desiccated. Mechanical As needed As needed
Provide addition irrigation or By hand
and fertilizer as needed.
Plants are dead, diseased Mechanical As needed As needed
or dying. Determine the or By hand
source of the problem:
soils, hydrology, disease,
etc. Remedy the problem
and replace plants. Provide
a one-time fertilizer
a lication.
Nuisance vegetation is By hand As needed As needed
choking out desirable
species. Remove
ve etation b hand if

possible. If pesticide is
used, do not allow it to get
into the receivin water.
The Swale and Level Li
The swale is clogged with Mechanical As needed All year
sediment. Remove the or By Hand
sediment and dispose of it
offsite.
The level lip is cracked, By hand As needed All year
settled, undercut, eroded or
otherwise damaged. Repair
or re lace li .
There is erosion around the Mechanical As needed All year
end of the level spreader or By hand
that shows stormwater has
bypassed it. Regrade the
soil to create a berm that is
higher than the level lip, and
then plant a ground cover
and water until it is
established. Provide lime
and aone-time fertilizer.
Trees or shrubs have begun Mechanical As needed As needed
to grow on the swale or just or By hand
downslope of the level lip.
Remove trees or shrubs.

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DATE: 3-19-08 -
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