20070666 Ver 3_More Info Received_20080620

07- D69 v 3
C ENGINEERING
TRANSMITTAL LETTER
TO: Ms. Annette Lucas
NCDENR- Division of Water Quality
401/Wetlands Unit
2321 Crabtree Blvd
Raleigh, NC 27604
We are transmitting:
a-*"Attached
? Under Separate Cover
? Via email / ftp
The following items:
a-'Plans
? Drawings
? Application/Fee
CH Engineering, PLLC
4601 Lake Boone Trail
Raleigh, NC 27607
919.788.0224
919.788.0232 (fax)
DATE JOB NO:June 18, 2008 1
RE: Broughton Properties
Delivered via:
courier
? Overnight Delivery
? Mail
? Plats
? Specifications
? Shop Drawings
Sher
? Digital Files
? Change Orders
? Documents
COPIES DESCRIPTION
1 Plan & Profile Sheets PP-1, PP-2
1 each C-2 overall layout with Drainage Areas delineated (Comment 1) as
well as boundary of the BMP maintenance easement comment 2e
5 sets Supporting calculations, revised bioretention supplement
forms(Comment 2a), SM-1 & SM-2 @ 30 Scale with Specifications
for Medium (Comment 2b), slope for the underdrains as well as
outlets for the underdrain systems (comment 2c). SM-1 contains the
revised terraced bioretention construction sequence with clarification
That the bioretention area must be 50 feet away from the stream.
rY For Approval ? Approved as Submitted
? For Your Use ? Approved As Noted
? As Requested ? Returned for Revisions
? For Distribution ? For Review and Comment
Cc: Mr. Ed Bai
Signed Z4 a4"', 'V"t- D LI ``!
JUN 2 0 2008
DENR -WATER QUA JTY
t.NETI_ANDS AND STQRMWATER BRANCH
ENGINEERING
CALCULATION SHEET PAGE OF
?, v y
CLIENT ??J'j SUB ECT ? t. ????" ?? ?? Prepared By M Date /fl PROJECT No. (? - t^ -?.,)N i /. , ' . Reviewed By Date
AMP AcA= 330 sr 4?' sue' L-0 ?1t
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JUN 2 0 2008
DENR -WATER UUAUTY
We:UNNDS AND STORMWATER BRANCH
Preliminarv Sioretention Area Cal(--q fnr Rrniinhfnn Prnnorfioc I I r
Site Area Assumed Imp. Rv WQV (cf) Depth(inches) Basin Area L W
S-1 58,642 60% 0.59 2883 12 2883 71 41
S-2 45,958 60% 0.59 2260 12 2260 62 36
S-3 66,922 60% 0.59 3290 12 3290 70 47
S-4 30,138 60% 0.59 1482 12 1482 50 30
(R-1) + (S-5(1)) 131,653 68% 0.662 7263 12 7263 135 54
S-6 121,414 60% 0.59 5970 12 5970 100 60
S-7 170,681 60% 0.59 8392 12 8392 120 70
S-8(1) 146,200 60% 0.59 7188 12 7188 135 53
S-8(2) 104,077 60% 0.59 5117 12 5117 100 51
(R-2)+ (S-5(2)) 61,532 75% 0.725 3718 12 3718 70 53

0.05 0 12 0
0.05 0 12 0
0.05 0 12 0
Permit Number:
(to be provided by DWQ)
? OF W A TF?
NCDENR °
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 lll) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATIONi -
Project name OAK FOREST ROAD EXTENSION
Contact name THOMAS HEPLER
Phone number 919-788-0224
Date JUNE 17. 2008
Drainage area number R-1 ROADWAY WEST
JI. DESIGN`INFORMATION -?
Site Characteristics
Drainage area 131,653.00 ft2
Impervious area 89,492.00 ft2
Percent impervious 68.0% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
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 7,263.00 ft3
Storage Volume: SR Waters
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0.00 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12:00 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 8235.00 ft2 OK
Length: 250.00 ft OK
Width: 33.00 ft OK
-or- Radius ft
Soils Report Summary
Drawdown time, ponded volume 2.00 hr OK
Drawdown time, to 24 inches below surface 12,00 hr OK
Drawdown time, total: 14.00 hr
In-situ soil:
Soil permeability 0,65 in/hr OK
Planting media soil:
Soil permeability 1.50 in/hr OK
Soil composition
% Sand (by weight) 85% OK
% Fines (by weight) 12% OK
% Organic (by weight) 3% OK
Total: 100%
Form SW401-Bioretention-Rev.3
Parts I and II. Design Summary, Page 1 of 2
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?
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 localed 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 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
(81inches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay
15 (unitless) OK
284.00 fmsl
283.00 fmsl OK
281.00 fmsl
2.00 ft
2.00 inches OK
270.00 fmsl OK
Y (Y or N)
9 OK
2.00 OK
1ft
280.00 fmsl
10.00 ft OK
Y (Y or N) OK
N (Y or N)
N/A OK
N/A OK
N/A OK
Y (Y or N) OK
Permit Number:
(to be provided by DWQ)
N (Y or N) Excess volume must pass through filter.
r ?4 - BoX TANGS ?'K_-"? /7L
`
N/A ft rtl 5 S P a n?a ct'E ,1
r sr 0°.:.. i•.l r?
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
1.00 ft/sec OK
N (Y or N) OK
N' (Y or N) OK
Y (Y or N) OK
OK
X'
Form SW401-Bioretention-Rev.3 Parts 1 and II. Design Summary, Page 2 of 2
Permit Number:
(to be provided by DWQ)
AM*4 OF W A rF9
?i
NCDENR
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 III) must be printed, filled out and submitted along with all of the required information.
IL PROJECT INFORMATION`
Project name OAK FOREST DRIVE EXTENSION
Contact name THOMAS HEPLER
Phone number 919-788-0224
Date June 17, 2008
Drainage area number R-2 ROADWAY EAST
II. DESICNANEORMATION
Site Characteristics
Drainage area 61,532.00ft2
Impervious area 46,334.00 ft2
Percent impervious 75.3% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
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 3,718.00 ft3
Storage Volume: SR Waters
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft3
Minimum volume required 0.00 ft3
Volume provided ft3
Cell Dimensions
Ponding depth of water 12'00 inches OK
Ponding depth of water 1.00 ft
Surface area of the top of the bioretention cell 4100.00. ft2 OK
Length: 150.00 ft OK
Width: 27.50 ft OK
-or- Radius ft
Soils Report Summary
Drawdown time, ponded volume 2.00 hr OK
Drawdown time, to 24 inches below surface 12.00 hr OK
Drawdown time, total: 14.00 hr
In-situ soil.-
Soil permeability 0.65 in/hr OK
Planting media soil.-
Soil permeability 1.50 in/hr OK
Soil composition
% Sand (by weight) 85% OK
% Fines (by weight) 12% OK
% Organic (by weight) T. OK
Total: 100%
Form SW401-Bioretention-Rev.3 Parts I and II. Design Summary, Page 1 of 2
Phosphorus Index (P-Index) 15 (unitless) OK
Basin Elevations
Temporary pool elevation 294.50 fmsl
Planting elevation (top of the mulch) 293.50 fmsl

Bottom of the cell
291.50 fmsl OK
Planting depth 2.00 ft
Depth of mulch 2.00 inches OK
SHWT elevation 270.00 fmsl OK
Are underdrains being installed? Y (Y or N)
How many clean out pipes are being installed? 5 OK
What factor of safety is used for sizing the underdrains? (See

BMP Manual Section 12.3.6) 2.00 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 290.50 fmsl
Distance from bottom to SHWT 20.50 ft OK
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 Plan
Number of tree species N/A
Number of shrub species N/A
Number of herbaceous groundcover species N/A
Additional Information
Does volume in excess of the design volume bypass the N or N
)
bioretention cell?
Does volume in excess of the design volume flow evenly N/A (Y or N)
distributed through a vegetated filter?
What is the length of the vegetated filter? N/A ft
Does the design use a level spreader to evenly distribute flow? N (Y or N)
Is the BMP located at least 30 feet from surface waters (50 feet if

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

recorded access easement to a public Right of Way (ROW)?- Y (Y or N)
Inlet velocity (from treatment system) 1.00 ft/sec
Is the area surrounding the cell likely to undergo development in

the future? 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
(81inches gravel followed by 3-5 ft of grass)
Grassed swale
Forebay X
OK
OK
OK
Permit Number:
(to be provided by DWQ)
Excess volume must bypass cell.
(spL- . ?f e- < iA,L s Io
Enter Data
Show how flow is evenly distributed.
OK y
OK
OK
OK
OK
OK
OK
OK
OK
Form SW401-Bioretention-Rev.3 Parts I and II. Design Summary, Page 2 of 2
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EMERGENCI?SPtLLiNAYEtEV 2$4.0 q??,<\ ?? - P?
CLASS B10UTLEYPADS FOR UNDERD_R_AIN_ SYSTEM` p 0 j TERRACED BIORETENTIONCONSTRUCTION
cl) SEQUENCE
1. CONTRACTOR SHALL ENSURE THAT THE BIORETENTION AREA
.21 \ r?Q \ AND,
FOREBAY ARE PROTECTED FROM SEDIMENT AND
?$TOMWATER RUNOFF FROM UNSTABUZEDAREAS. THEREFORE,
I
/ ,, / ',? / l l l 1 T _ BIORETENTION AREAS SHALL BE CONSTRUCTED AFTER THE SITE
% I ! ! r ! I I I ( ' / HAS BEEN STABILIZED TEMPORARY SEDIMENT BASINS ARE TO
I I I' ; i ?'l I / - REMAIN IN PLACE UNTIL THE CONTRIBUTING SITE HAS BEEN
r /
STABILIZED. A TEMPORARY STORMWATER DIVERSION MAYBE
00 - - _ _ _ _ - -, NECESSARY UNTIL THE BIORETENTION BASIN HAS BEEN
COMPLETED AND A GRASS MEDIUM ESTABLISHED IN THE BASIN
AND SIDES.
Ift, ', I rll''?/ I /; f / 'HIGH,WATEREL.284.0 ' ------- _
2. PRIOR TO CONSTRUCTION OF THE BIORETENTI ON BASIN
1 I it iA,? V / , f 1 / / l 1 1 / - CONTRACTOR TO VERIFY THAT BASIN AND ALL ITS AM ENTITIES
ARE A MINIMUM OF 50 FEET AWAY FROM THE STREAM BANK
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( 1 I ' 7. CONTRACTOR IS TO MAKE BEST EFFORTS TO ENSURE THAT THE
I rl 1 I 1 BIORETENTION TERRACE IS CONSTRUCTED ACCORDING TO
!I 7 I PLANS AND THE SPUTTER BOXES SERVING THE BASIN ARE
f ! r I I lI I 7 I ! / - - - -' - FUNCTIONING PROPERLY. ONCE UNDERDRAINS ARE INSTALLED
l ( 1 /? ( I , r I j ' THE CONTRACTOR SHALL NOT OPERATE HEAVY EQUIPMENT
I 1
OVER THE PIPE. CONTRACTOR SHALL CALL FOR ENGINEERS
/
/ Ir I I 1 ,---- INSPECTION AT A MINIMUM OF THE FOLLOWING:
I / 1 I I I I ! I. UPON COMPLETION OF THE WALL
I ? // ? I r jI I I ;'?
1
II. AFTER INSTALLATION OF THE UNDERDRAIN
V
I / I ! III. UPON DELIVERY OF THE FILL MEDIUM TO BE USED
I , I
I IV. UPON COMPLETION OF BASIN WITH SEED] NGISPRIGGING
I I rl 1 ?, I , r I I COMPLETE.
i I? •? =. E I ? I ? ? I
SPECIFICATIONS FOR BMP MEDIUM:
2- 6" WNDERDRA',1NS @';0.50 °fo
1. THE SOIL MIX MUST BE UNIFORM AND
II Il j i 1 / FREE OF STONES, STUMPS, ROOTS, OR
I j OTHER SIMILAR MATERIAL GREATER
1 I,
THAN 2 INCHES.
1 \ 2. SOIL TEXTURE OF THE MIX USED FOR
I
j, I `•r1 \ I BMP MEDIUM SHOULD BE LOAMY SAND,
WITH NO MORE THAN 10% CLAY
CiPAFilUMS t3A5t 1/y.5 /-WP 284.5 MIN. ?? (USDA SOIL TEXTURAL CLASSIFICATION)
\ A MINIMUM ORGANIC CONTENT OF 5%
LEVELI,OF TEAiIENT AREA = 7400 SF " I
I it At FORTURFAREAS. PROVIDE WATER
TOLERANT GRASSES.
! 823 SFAREA(PWG) 3
44+/-?! aC RE S
4 82`5 CF TREATMENT @ 12" DEPTH 3. THE PH SHOULD BE BETWEEN 5.5 AND 7.0.
IF THE PH FALLS OUTSIDE OF THIS RANGE, IT
1 ' G
MAYBE MODIFIED WITH LIME TO INCREASE THE
I R-111 I PH OR IRON SULFATE AND SULFUR TO LOWER
THE PH. THE LIME OR IRON SULFATE MUST BE
MIXED UNIFORMLY INTO THE SOIL PRIOR TO USE.
INj ?j $MP MAINTENANCEtASDMENT" (PU?LIC;) i_
/
I << ? ' / I I ? 1
FOR SECTION A-A SEE SHEET SM-2
JUN 2
300 X15 30 do
s
DENR-WATE
WETLANDS ANDSTMr-
. i
??OREBA?'-EC€ l ? -

A
\
` V. 28310

YIN-AREA 1_02-SF'(T ?5')
i
'
PROJECT ND: CV502 SHEET
DATE:
DRAWN: ?? ¦¦
SM 1
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FAAA? C .? 7 : f / LNECJLED: TgH
SCALE: SHEET OF
I Vvn?yrvi LLLV, 4_UJu MIN, AREA1_02SF(TX;f5') -
1 ; a,:/PVQ
'
N
GRASS FILTER STRIP;
i i
?i CLASS STONE QUTCET PADS FOR UNDERDRAt1v SYSTEM s
r
iEMERGENCYSPILLWAY ELEV. 294.5
279.5
;Ct14
i
I
! I ;I °GAB(IO,NS BASE 290.0 TOP 295.0 SIN.
i . (I I ! 1' / ??
i
4100 SF AREA (AVG) r \
14 s
??' ?i vk ' % ? l I' ?I 100 CFit REATME IT @ 12" DEPTH
- - '
2- UNDERpRAINS @ 0.50% ; -
,,',0 `W ION) EASE ESN`,
VIII) ) j ? ? ? ? \ \ '=\ 1 ?
130
`-A, LEVEL TRE?TMENT AREA= 4534 SF
7'? \ I V v `?A HIGH WATER EL. 294.50
r
1 _ AA ? ? 1 11
15 30 60
30 ` -0-
A` vv A v ?v v
8 PVC FORE BAY ELEV. -293.5 BASE e
WITH C;[( w v,? A ?; 1 R_? y ARLA= 9USF (6' X 15' MIN.)!
-id' X 27" T ICK vv ??4
1
JCL 11 RIPRA
?? v
I?Ut?= 279.00 g3•5 ?. PV6
-0
24" RCP - - Y - - _ -
s

l BOX

1v. ? U x ? ? y va
\16Ply

Ho. oa v isioN
WATER TOLERANT GRASS
20' (AVG) 12' . 4'
3
12" SAND & SOIL MIX
24" SAND
UNDER DRAINS
SEMI-PERMEABLE MEMBRANE
SECTION A-A
NO SCALE
NOTE: FOR SOIL SPECIFICATIONS SEE SHEET SM-1
br ?
0,
r
6" PERFORATED PVC
MIN. 3" OF 57 STONE
FILTER FABRIC
EXISTING GROUND PROFILE
MEDIA PLANTED WITH FOREBAY
WATER TOLERANT GRASS
16' (AV(3) , 12' . 4' , 10'
3
12" SAND & SOIL MIX
24" SAND
UNDER DRAINS
SEMI-PERMEABLE MEMBRANE
Lj?v, RI\Nt-bf-W*y) SECTION a-e
A?O SCALE
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PROJECT N0: CV502 SHEET
DATE: 4-29-08 3
DRAWN: MJL SM-2
CHECKED: TRH
SCALE: AS SHOWN SHEET OF