HomeMy WebLinkAbout20090689 Ver 1_Stormwater Info_20090610D C3 14 4 Lo
Stimmel
June 9, 2009
Ms. Annette Lucas
Stormwater and Wetland Coordinator
NCDENR -DWQ Wetlands Unit
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604 ?J
Re: Kernersville Medical Parkway Linear Project JUN 1 0 2009
Kernersville, North Carolina DENR - WATER QUAUTY
WETLANDS ANO STORMWATER BRANCH
Dear Annette:
Attached you will find narratives, drawings and details, drainage area exhibits and calculations for the
stormwater management devices to serve for the Kemersville Medical Parkway linear project. This
information is submitted for your review and comment.
Kemersville Medical Parkway is being built by a private developer and the roadway will be turned over to
the Town of Kernersville as a public roadway upon completion. The construction of the roadway will
impact the West Fork Deep River, two small unnamed tributaries and associated wetlands. These
impacts are being permitted under a nationwide permit through the US Army Corps of Engineers and
requires 401 certification from the NCDENR - Division of Water Quality.
The project consists of constructing a four lane collector roadway, with median, from Macy Grove Road to
NC 66 totaling approximately 6,500 linear feet. The project is divided in two phases. The first phase is
from Macy Grove Road to just east of the West Fork Deep River, consisting of approximately 2,325 linear
feet. Stormwater quality treatment for the eastern 1,475 If of Phase 1 is provided by a wet detention pond
located on the Novant Hospital site. The roadway drainage area going to the pond extends from Macy
Grove Road to the western entrance into the hospital. As you and I discussed during my visit to your
office, this pond provides water quality stormwater management for the hospital site and surrounding
outparcels in addition to a portion of the roadway. The pond was reviewed and permitted by the Town of
Kernersville under their NPDES Phase II Stormwater and Watershed Supply Watershed Ordinances.
Stormwater quality treatment for the remaining 850 If of the Phase I section of the roadway and the
eastern 650 If of the Phase II section of the roadway will be provided by a bioretention cell located outside
the public right-of-way just east of the West Fork Deep River. Stormwater quality treatment for the
remaining 3,525 If of the Phase 11 section of the roadway will be provided by two bioretention cells, also
located outside the right-of-way within private property.
Specific information included is as follows:
Parkway Phase 1
• Stormwater Report with Narrative, DWQ Bioretention Cell Supplement, Plunge Pool Calculations,
Drainage Area Exhibit and Seasonal High Water Table Report
• Drawing Sheets: C-3.1, C-6.0, C-7.0 and C-7.1
601 N. Trade Street, Suite 200
Winston Salem, NC 27101
P: 336.723.1067 F: 336.723.1069
Parkway Phase 11
• Stormwater Report with Narrative, DWQ Bioretention Cell Supplement, Plunge Pool Calculations,
Drainage Area Exhibit and Seasonal High Water Table Report
• Drawing Sheets: C-3.2, C-3.3, C-3.4, C-3.5, C-6.0, C-7.0, C-7.1 and C-7.2
Kernersville Medical Center Wet Detention Pond
• Drawing Sheets: C-6.0, C-6.1, C-6.2, C-6.3, C-6.4, C-6.5 and Drainage Area Exhibit
Plans for the wet detention pond and the associated drainage area map are included for informational
purposes. Calculations for the wet detention pond are not included since the pond was permitted by the
Town of Kernersville. If you have any questions or need additional information, please call me at (336)
723-1067.
Sincerely,
J. Neal Tucker, P.E.
Director of Civil Engineering
Stimmel Associates, PA
cc: File
STORMWATER MANAGEMENT CALCULATIONS FOR:
KERNERSVILLE MEDICAL PARKWAY
PHASE I
KERNERSVILLE, NC
Project # 08-032
Prepared for:
TRADE STREET DEVELOPMENT CORPORATION
RfN@ffl0w[EJ
JUN 1 0 2009
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sapa
Landscape Architecture
Civil Engineering
Stimmel Associates, PA Land Planning
DENR - WATER QUALITY
WETLANDS AND STORM WATER BRANCH
601 N. Trade Street
Suite 200
Winston Salem, NC
27101-2916
P: 336.723.1067
F: 336.723.1069
May 29, 2009
. ?
,.
TABLE OF CONTENTS
STORMWATER MANAGEMENT NARRATIVE
BIORENTENTION CELL CALCULATIONS
DRAINAGE AREA EXHIBIT
SEASONAL HIGH WATER TABLE EVALUATION REPORT
STORMWATER MANAGEMENT NARRATIVE
STORMWATER MANAGEMENT NARRATIVE
INTRODUCTION
The project is located in Kernersville, NC, West of Macy Grove Road, East of the West Fork Deep
River and just North of 1-40. The project is a linear project consisting of constructing a four lane
with median roadway within a right-of-way that will be dedicated to the Town of Kernersville.
Approximately 4.19 acres will be disturbed. Total impervious area is 2.33 acres, which will drain
to a single bioretention cell for water quality treatment. Treated water will discharge into a
perennial tributary of the West Fork Deep River. The site's existing condition is undeveloped and
was used as farmland in the past. The proposed stormwater management system consists of a
bioretention area. Runoff detention for channel protection and peak attenuation will not be
required per the Town of Kernersville; however, they are requiring a plunge pool at the device
outfall.
METHODOLOGY
The bioretention cell was sized using the current NCDENR spreadsheet and methodology. The
USDA Soil Conservation Service's Soil Survey of Forsyth County, North Carolina2 (Soil Survey)
was used to determine the existing soil group classifications. Soils present on this site have a
hydrologic soils group classification of `B'.
The site is currently undeveloped; however, it was used as farmland in the past, a composite pre-
developed rational coefficient of .35 was calculated. The composite post-developed managed
coefficient of .68 was calculated based on the impervious coverage of the proposed roadway.
Coefficient calculations with references are included in the appendices.
Rainfall data used in the hydrologic analysis for the project was taken from Technical Paper No.
40 - Rainfall Frequency Atlas of the Unites States' (TP-40), published by the U.S. Department of
Commerce.
Hydrographs were computed using the Rational Method.
Pipe flow out of the stormwater management system was calculated under both inlet and outlet
control, and the lesser of the two outflows taken as the control. A weir coefficient of 3.33 was
used.
Storm hydrograph routing through the device was performed using the Storage Indication Method
as outlined in NEH-4. A brief summary of the routing results is included at the end of this
narrative. Detailed routing calculations are included in the appendices.
SYSTEM CONFIGURATION
The stormwater management device proposed for this project is a bioretention cell for water
quality treatment. Due to the concentrated flow into the device, a forebay will be provide for
pretreatment and energy dissipation, while a plunge pool will provide the required outfall energy
dissipation and some sheet flow into the buffer area.
The cell layers will consist of 2" hardwood mulch, 2 feet soil planting media, 4 inch washed sand
and 8 inch washed stone, with a total depth of 3.17 feet. The treatment surface area required is
8367 square feet, while the surface area provided is 10,280 square feet.
According to the geotechnical engineering report, no groundwater was encountered above end of
boring depth of 20 feet. A seasonal high water table investigation was conducted. The SHWT in
the area the device is proposed was found to be six feet below the surface. The outfall of the cell
will be a 6" underdrains flowing into a 4 sided yard inlet with a 24 inch barrel outlet. The
bioretention cell will have a 12 inch ponding depth. Flows above the ponding level will be
controlled by the yard inlet. Here is a summary of the system control elevations:
Control Point Elevation
Riser barrel invert 879.65
Weir 884.75
To of Riser 885.58
Device Bottom 879.15
To of dam 885.00
The system will not provide peak attenuation to pre-development levels per Town of Kernersville
requirements. Design computations for the system follow this narrative.
REFERENCES
(1) Soil Survey of Forsyth County, North Carolina, USDA Soil Conservation Service,
May 1976
(2) National Engineering Handbook Section 4-Hydrology, USDA Soil Conservation Service, 1972
(3) Technical Paper No. 40 - Rainfall Frequency Atlas of the Unites States for Durations from 30
Minutes to 24 Hours and Return Periods from 1 To 100 Years, U. S. Department of
Commerce, May 1961
BIORETENTION CELL CALCULATIONS
Permit IN um uer.
to be provided by DWQ)
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.
1. PROJECT INFORMATION
Project name Kemersville Medical Parkway
Contact name Omar Ching, PE
Phone number 336-723-1067
Date May 26, 2009
Drainage area number 1 -Phase One of Kemersville Medical Parkway
11. DESIGN INFORMATION
Site Characteristics
Drainage area 182,114 ft2
Impervious area 101,495 ftz
Percent impervious 55.7%
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 8,367.0 ft3
Volume provided 10,280.0 ft3 OK
Storage Volume: SA Waters
1.5 runoff volume ft 3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24-hr runoff ft 3
Minimum volume required 0 ft3
Volume provided ft 3
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 10,280.0 ftz OK
Length: 155 ft OK
Width 65 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 12 hr OK
Drawdowr time, to 24 inches below surface 36 hr OK
Drawdown 'lime, total 48 hr
In-situ soil
Soil permeability 1.00 ;niter OK
Planting .media scil
Soil permeability 1.00 Iml r OK
Scii composition
Sand (by weight; 87% OK
',io =:res 'by weight; 9% O'K
C gari c (by weight; 4% OK
c;al 120%
^cscrc',-s ex - ^dex ^r edla 20 , 7°SS1 OK
=?r 3'i`? 3 ^re:er 3ev_7 gars a-a 'asgr Su teary ?age ' _
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
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-riches gravel followed 'oy 3-5 ft of grass)
Grassed swale
Forebay
Other
3?
884.75 fmsi
Y (Y or N) OK
N (Y or N)
883.75 fmsi
inches
881.75 fmsi
2ft
0.25 ft
Y (Y or N)
14 OK
2 OK
1ft
880 5 fmsl
874 fmsl
6.5 ft OK
Permit Number.
(to be provided by DWQ)
Y (Y or N) OK
Y (Y or N) OK
30 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
X
OK
PaCS a^e --esigr 3--^ a-y ?age 2 0- 2
Hydrograph Deport
Hydraflov: Hydrographs by intelisolve v9.1 Wednesday. Jun 3, 2009
Hyd. No. 2
Rat. Route
Hydrograph type = Reservoir Peak discharge = 0.000 cfs
Storm frequency = 10 yrs Time to peak = nla
Time interval = 1 min Hyd. volume = 0 cuft
Inflow hyd. No. = 1 - Biocell #1 Max. Elevation = 884.74 ft
Reservoir name = Biocell #1 Max. Storage = 9,816 cuft
Storage indication method used.
Q (d S)
18.00
15.00
12.00
9.00
6.00
3.00
r. no
?V
2
Hyd N1n 2
Rat. Route
Hyd. No. 2 -- 10 Year
A 8 10 12 14 "^ 13
- -Hyd No. 1 Total storage 1 sed = 9,816 cuft
Q (cfs)
18.00
15.00
12.00
9.00
6.00
3.00
0.00
20
Time (rain)
Ponce Report
?ydraflovu Nydrogr phs by Intellsolve v9.1
Pond No. 1 - Biocell #1
Pond Data
Contours - :lser-defined contour areas. C onic methoa used for volume calculation. Begining Elevation = 883.75 ft
Stage t Storage Table
Stage (ft) Elevation (ft) Contour area (sgft) Incr. Storage (cult) Total storage (cult)
0.00 883.75 8,926 0 0
0,25 884.00 9,246 2,271 2,271
1.00 884.75 11,065 7,606 9,877
1.25 885.00 11,471 2817 12,693
Wednesday, Jun 3, 2009
Culvert /Orifice Structures
[A] [B] [C] [PrfRsr]
Rise (in) = 30.00 0.00 0.00 0.00
Span (in) = 30.00 0.00 0.00 0.00
No. Barrels = 1 0 0 0
Invert El. (ft) = 879.65 0.00 0.00 0.00
Length (ft) = 48.00 0.00 0.00 0.00
Slope (%) = 0.31 0.00 0.00 alga
N-Value = .013 .013 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60
Multistage = rJa No No No
Weir Structures
[A] [B] [C] [D]
Crest Len (ft) = 15.00 0.00 0.00 0.00
Crest El. (ft) = 884.75 0.00 0.00 0.00
Weir Coeff. = 3.33 3.33 3.33 3.33
Weir Type = Riser - --- -
Mufti-Stage = Yes No No No
Exfil.(in/hr) = 0.000 (by Contour)
WJ Elev. (ft) = O.Co
Note- CuivertiOrifice outflows are analyzed under inlet QS.) and outlet (m) control. Weir risers checked for orifice conditions (ic) and submergence. (s).
Stage (ft)
2.00
T-
.8Q i
1.60
1.40
1.20
1.001
0.80
0.60
I
0.40
0.20
Stage / Discharge
0.0 11.00 1.00 2.00 3 00 4 00 500 6,00
Total 0
700
Discharge (cis)
Elev (ft)
885.75
885.55
885.35
885.15
884.95
884.75
884.55
884.35
884.15
883.95
Q?Z? 7K:
Hydraflow Rainfall Deport
Hydraflow Hydrographs by lntelisoive v9.1
I Return
f P
i
d intensity-Duration-Frequency Equation Coefficients (FHA) i
er
o
4 (Yr s) E ft,'aa
1 j 0.0000 0.0000 0.0000 --------
2 i
_ I 3_ I
R.8943
.. 8.2OQ0 72 i
0..75. _ ----
3 i
0.0000 1 0.0000 0.0000 ----
5 1 49.1292 9.8000 I 0.7553
10 57.1093
1 10.7000 0.7573
f - - -
25 ! 68.6696 } 11.6000 07600 ? -----
50 78.1106 12.2000 0.7626
100
I 88.1981
? ! 12.8000
; 0.7663 j
1 - -
I
File name: ForsythADF
Intensity = B J (Tc + D)^E
Wednesday, Jun 3, 2009
Return '
P
i
d intensity Values (in/hr)
er
o
(!rs) 5 Mir. ?0 i 45 1 20 } 25 i 34 } 35 40 45 50 i 55 60
1 OM 0.00 0.00 0.00 0.00 I 0.00 I O.OO 0.00 I 0.00 0.00 0.00 0.00
+ 2 1
1 ' 5.51 i
i 4.32
i I 3.60
} 310 I
i 2.74
? 2.47 1I 2.25 1
; 2.07 I
I 1.92 1.79
} 1.68 1.59
I
3 f
0.00 I 0.00 0.00 0.00 0.00 0.00 ' 0.00 I 0.00 I 0.00 I 0.00 0.00 I 0.00
} 5
6.42 }
5.15
4.35 ! !
3.78
i
3.36 , s
3.04
} 2.78
2.57 }
239 !
024
2.10
1.99
10 ( 7.10 5.76 4.89 i
III 4.27 !
! I
3.81 3.45
? 3.16 2.92 ( 2.72 2.55 1
lll
llll `
2.40 ( 2.27
2
} 5 1 8,12 I
8.1 i
6.65 I I
i 567 I
6. I
4.98
} ,.?
n 4,45
4.04 i I
3.71 }
_
143
3.20 1 ' n
i
100 i a n?
2.82 1 ?
-.67
I
50 ( 8.92 7.34 6.29 I 5.53 4.95 4.50 4.13 I 3.83 3.57 I 335 3.16 I 2.99
j 100
1 9.71 8.03
1 6.90
i i 6.08
1 ` 5.45 4.96 4.56 4.22 !
I 3.94 3.70 } 3.48 {
i 3.30
l
Tc = time in minutes. Values may exceed 60.
prcnin ftla names- ?amnlc -. n
I Rainfall Precipitation Table (in)
Storyn
I Distribution } 1-yr i 2-yr 3-yr 5-yr 1 10-yr 25-yr } 50-yr 100-yr
SGS 2Thour 0.00 2.20 0.00 3.30 4.25 1 5.7 6.80 7.95
6-Hr 1 ' 1. +:; 4 n" ii
` Huff-1st 0.00 ` 1.5r 0.00 2.75 4.00 5.38 ! 6.50
I
8.00 }
i u..a: .
luu-2i1u ?
G.vi, i 10. 10 I
G.uG 1
i:.a G i n n
v.uG 1 v.uv i
v.Gu 1
^,.;G
}
Huf;,31d 0.00 1 0.00 1 0.00 0.00 ? 0.00 y .0..'.30 i G.GG 0.00 I
i
riu K u-4iii I
G.GG I 0.[)0 1
G."vG f
0.00 I 1
G.GG } G.u"G
0.00
U-. U--
1 Huff-Indy OM ! 040 G. ; C.+:i `
0-CC ! 000 I `
Q. U9 n
010
cu--1Orn :, uG 1.75 0.-3 0 2.10 I 3 .0 5,25 , 6.00 7,1C)
RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET (Version 8.99)
(Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
JOB:
DESIGNER Date: 5/27/2009
CHECKER: Date:
INPUT DATA:
Conduit Diameter
Conduit Discharge:
Conduit Slope at Outlet:
Conduit Outlet Invert Elevation:
Tailwater Elevation:
Outlet Channel Invert Elevation:
Water Density:
Bed/Riprap Particle Density: (Default 2.64)
D, 50 Riprap Size:
Riprap Thickness: (2.5*D, 50 recommended)
Bedding Thickness: (6 inch min. rec.) (Enter 0 for geotextile)
Side Slope Ratio:
Upstream End Slope Ratio:
Downstream End Slope Ratio:
Combined End Slope Ratio:
OUTPUT---POOL LOCATION AND DIMENSIONS:
Vert. Dist. from Tailwater to Conduit Invert:
Submergence Check: (If Zp < 0 , Use Zp = 0)
Beaching Check: (Q/(gD^5)^0.5 <_ (1.0+25*D,50/D)]
**Beaching Controlled**
Distance from Conduit Exit to C/L Pool:
Pool depth at C/L Below Conduit Invert:
Pool Bottom Elev:
Pool Bottom Length:
Pool Bottom Width:
Upstream Pool Length at Tailwater Elev.:
Downstream Pool Length at Tailwater Elev.:
Pool Width at Tailwater Elev.:
Check Side Slope Ratio: (Wr-We)
**INCREASE SIDE SLOPE RATIO, Zw**
Check Min. End Slope Ratio: (Lru & Lrd - Le)
**INCREASE END SLOPE RATIO, Zlu**
Check Upstream Length: (Lru - Xm)
**INCREASE END SLOPE RATIO, Zlu**
Pool Bottom Elev. at Bottom of Riprap:
Pool Bottom Elev. at Bottom of Bedding:
OUTPUT---VOLUMES BELOW WATER SURFACE ELEVATION:
Volume of Excavation (measured from bottom
surface of bedding):
Volume of Rack Riprap
Area of Geotextile
D= ft
Q = r cfs
S 3 ft/ft
El, CO = ._ _ . ft
El, TW ft
El, CH = J.J ft
RHO =
RHOS =
RS =
RT =
BT =
Zw =
Zlu =
Zld =
Z1 =
1.00
2.64
u
4. y0:
C
3.50
ft
ft
ft
ft/ft
ft/ft
ft/ft
ft/ft
Zp =
Use Zp =
Xm =
Zp+0.8Zm =
EI,PB =
2Lr2 =
2Wr2 =
Lru =
Lrd =
2Wr =
1.00
1.00
O. K.
0.37
-1.25
103.75
-1.88
-1.77
-9.93
-7.68
-10.76
*PROBLEM*
ft
ft
ft
ft
ft
ft
ft
ft
ft
ft
*PROBLEM*
*PROBLEM*
El, BR = 101.25 ft
El, BB = 101.25 ft
V, pbs = 0.0 cu yd
V, rs = 6.1 cu yd
A,gt = 0.2 sq yd
Spreadsheet developed by D Hurtz, Midwest NTC, 1/90
Spreadsheet modified by M. Dreischmeier, Eau Claire TC, Wis . 3,98
Design Note No. 6 (Second Edition), Jan 23, 1986
RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET
Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
Elev. 102.5 Elev.
100.0
Elev.
-1.2 103.7
-1.9
1 1
4.0 3.0
«- -1.2?
t-- 0.4
-9.9 f -4.3
SECTION A-A
0.4
-10.8
2.5 2.0
«---0.6? SECTION B-B
B
A A
t A, IT, nn?
ROCK GRADATION
% Passing Size (in) B
100 24
60-85 18 LANDOWNER
25-50 12
5-20 6 DESIGNER:
0-5 2.4 SHEET OF
Exhibit 11
18
0
10,000
168 8,000 EXAMPLE (? ) (2) (3)
156 6,000 D•42 inches (3.5 foot) 6'
144 5,000 0.120 efs -
132 4,000 6. 5.
3,000 too 4
120 (1) 2.5 0.8 4.
2,000 (2) 2.1 7.4
108 (3) 2.2 7.7 4.
3.
jr. r.'
eD in lest 3.
96
1,000
k
800
84
_
600 2-
500 _ '
72 400 2•
N
W 300
?
1
5
v 6
/ .
f
2 60 U.
200
W
1
5
I
y_ 0 Z W .
54
o a
48
W
100
J ¢ 80
Q
/ =
0
60
y t-
(L
0 2
N
SO
H
W
E*TRANCE
° 1.0 1.0
40 SCALE
C TYPE I.0
W 36
30
(Iy-? Spears edge with W
t
9
•9
Q 33 headwall Q .9 ,
1 G
30 Z? '' (2) Groove end with
headsall W
2
8
. .8
(3) Groove end .8
27 projecting
?2 a 10
8
7
. r
7
6 To use scale (2) or (3) project
21 5 horizontally to scale (1), then
4 uss straight inclined line through
D and 0 scales, or reverse as 6
illustrated. 6 .6
15
L
5 .5
L
.5
1.0 .'
HEADWATER DEPTH FOR
HEADWATER SCALES 2d3 CONCRETE PIPE CULVERTS
BUREAU DP"LIC ROADS JAIL 1943 REVISED MAY 1964 WITH INLET CONTROL
VI-11
SEASONAL HIGH WATER TABLE EVALUATION
REPORT
ECS CAROLINAS, LLP
G otecliriicaf Construction Materials - Environmental
May 8, 2009
Mr. Hank Perkins
Trade Street Development Corporation
807 North Trade Street
V\rinston Salem, North Carolina 27101
Reference: Report of Seasonal High Water Table Determination
Kemersville Medical Parkway
Kemersville, North Carolina
EC-S Project 09-17129-A
Dear Mr. Perkins:
ECS Carolinas, LLP (ECS) is pleased to provide you with our Report of Seasonal High Water
Table (SHWT) Determination of the bioretention cell for the Kernersville Medical Parkway site
located in Kernersville, North Carolina. Our services were provided in general accordance with
ECS Proposal No. 09-15002-P.
PROJECT INFORMATION
The site is located on Kemersville Medical Parkway in Kernersville, North Carolina. ECS
received a site sketch provided by Stimmel Associates, P. A. identifying the four areas to
conduct a seasonal high water table investigation. The borings were drilled in the area adjacent
to the sediment basin and along a small creek. The borings were drilled outside of the 50 foot
stream buffer.
SCOPE OF SERVICES
ECS conducted an investigation of the soils to determine the seasonal high water table in the area
identified on the map. Soil borings were drilled with a hand auger to a depth of 120 inches,
observation/determination of the seasonal high water table, or auger refusal. The soil properties
and characteristics were observed and recorded in field notes. The properties include texture,
depth, the presence of restrictive horizons, depth to seasonal high water table, coarse fragments,
etv.
The assessment was conducted in accordance with current soil science practices and technology
and the North Carolina Division of Water Quality Stormwater Best Management Manual July, 2007.
The locations of the borings are depicted on a site map provided by Stimmel Associates, P. A.
Seasonal High Water Table Determination
Boring B1 The surface layer has a texture of clay loam, 4 to 5 inches deep. The structure appears
:dy inarr. in ? -#rs: -h>r=
iv v massive. .e s tJ Ewa. ubsurf-a a iye-r finor' 5 i o 30- ir'--hes ?a3 ? 3 baa.nsaw v of sandy -•r?t° ree of _ui
be v a ^?i a i i v a vv i? w? c?.J w , ? i. . I- - LVavf
appears to be granular with vex y friable consistence. The subsurface layer from 30 to 52 inches
ny.. 77- --- 17'-..,,..,. A-:_- o -,ii' 1'7;it;?-f"2 3T1 Q C4 -I a`f --'-,. .r"???Qz-- .?rn?
Seasonal High Water Table Determination
Kemersville Medical Parkway
Karners?ille, ,Month Catalina
ECS Project 09-17129-A
h-fa 13. 2009
has a texture of sandy clay loam. The structure appears to be subangular blocky with friable,
slightly sticky, plastic; consistence. The subsurface layer from 52 to 72 inches has textures of clay
loam and sandy clay loam. The structure appears to be massive with friable, slightly sticky, slightly
plastic consistence. The subsurface layer from 72 to 84 inches has a texture of sandy clay. The
structure appears to be massive with firm, sti&: ; plastic consistence. Common, few to medium,
distinct gray mottles (10YR 5/2) were observed at 72 inches. The matrix of this layer is gray (10YR
5/2) at 78 inches with yellowish brown mottles.
Boring B2 The surface layer has a texture of loam, 14 inches deep. The structure appears to be
granular with very friable consistence. The subsurface layer from 14 to 24 inches has a texture of
clay. The structure appears to be subangular blocky with firm, slightly sticky to sticky, plastic
consistence. The subsurface layer from 24 to 36 inches has a texture of sandy clay loam. The
structure appears to be massive with firm, sticky, plastic consistence. Common, few to medium,
distinct gray mottles (10YR 5/2) were observed at 24 inches. The matrix of this layer is gray (10YR
5/2) at 31 inches with yellowish brown mottles.
Boring B3 The surface layer has a texture of loam, 4 inches deep. The structure appears to be
granular with very friable consistence. The subsurface layer from 4 to 26 inches has a texture of
clay. The structure appears to be subangular blocky with friable, slightly sticky, slightly plastic
consistence. The subsurface layer from 26 to 120 inches has a texture of sandy loam. The
structure appears to be massive with friable consistence.
Boring B4 The surface layer has a texture of loam, 6 inches deep. The structure appears to be
granular %Mth very friable consistence. The subsurface layer from: 6 to 28 inches has a texture of
clay. The structure appears to be subangular blocky with friable, slightly sticky, plastic consistence.
The subsurface layer from 28 to 68 inches has a texture of clay loam. The structure appears to be
massive with friable, slightly sticky, slightly plastic consistence. The subsurface layer from 68 to
120 inches has a texture of loam. The structure appears to be massive with friable consistence.
Conclusions
Boring B1 The seasonal high water table was observed at 72 inches as indicated by the presence
of common, few to medium, distinct gray (10YR 5/2) mottles. The matrix of this layer is gray (10YR
5/2) at 78 inches with yellowish brown mottles.
Boring- B2 The seasonal high water table was observed at 24 inches as indicated by the presence
of common, few to medium, distinct gray (10YR 5/2) mottles. The matrix of this layer is gray (10YR
5/2) at 31 inches with yellowish brown mottles.
Boring B3 The seasonal high water table was found to be greater than 120 inches.
Boring B4 The seasonal high water table was found to be greater than 120 inches.
Seasonal Nigh !Water Table Determination
;;emerowdle Medical -Parkway
Kemers-ville, North Canofir?
ECS Project 09-17129-A
May 3, 2009
CLOSING
ECS is pleased to offer you our professional services and we look forward to assisting in any of
your site analysis needs in the future. if you have any questions or require further assistance,
please contact us at (336) 8056-715&
Respectfully,
ECS CAROLINAS, LLP
Joseph A. Hinton; !
Senior Soil Scientist
Soil
%4 A.
fL A ?.?
k? ;y j pout
042
Attachments: Figure 1
QtM?nis-e M/Pouf , LSS
Principal Scientist
cc: Omar Ching
? t M _l
lk?
i7?
3 I f-,
\cp B4 141
S '?
LEGEND
BI : BORING 1
5
B2: BORING 2 ?
B3: BORING 3? `
f
B4: BORING 4 'SOURCE:
S'TIMMEL ASSOCIATES, P. A.
SITE S1"x °`. l C] HE
SCALE 1,0 NCH = -135 FEET
FIGUREE. _1
SHW T
BID-RETENTION
=ERNERSVILLE MEDICAL PARK' AY
Ri RRS ILLE, NORTH CAROLINA
DRAINAGE AREA EXHIBIT
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00
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?e F-
STORMWATER MANAGEMENT CALCULATIONS FOR:
KERNERSVILLE MEDICAL PARK Y
PHASE I I ° @ff o 1C 0
KERNERSVILLE, NC JUN 1 0 2009
Project # 08-032
DENR - WATER QUALITY
WETLANDS AND STORMIWATER WANCH
Prepared for:
TRADE STREET DEVELOPMENT CORPORATION
Prepa
Stimmel Associates, PA
a SEAL '
033 51 •
sapa
Landscape Architecture
Civil Engineering
Land Planning
601 N. Trade Street
Suite 200
Winston Salem, NC
27101-2916
P: 336.723.1067
F: 336.723.1069
May 28, 2009
TABLE OF CONTENTS
STORMWATER MANAGEMENT NARRATIVE
BIORENTE= NTION CELL CALCULATIONS
DRAINAGE AREA EXHIBIT
SEASONAL NIGH WATER TABLE EVALUATION REPORT
STORMWATER MANAGEMENT NARRATIVE
STORMV'JATER MANAGEMENT NARRATIVE
INTRODUCTION
The project is located in Kemersville; NC, East of North Carolina Highway 66, West of the West
Fork Deep River and just North of 1-40. The project is a linear project consisting of constructing a
four lane with median roadway within a right-of-way that will be dedicated to the Town of
Kernersville. Approximately 21.92 acres will be disturbed. Total impervious area is 7:20 acres.
which will drain to two separate bioretention cells for water quality treatment. Treated water will
discharge into a perennial tributary of the West Fork Deep River. The site's existing condition is
undeveloped and was used as farmland in the past. The proposed stormwater management
system consists of two bioretention areas. Runoff detention for channel protection and peak
attenuation will not be required per the Town of Kernersville; however, they are requiring a plunge
pool at the device outfall.
METHODOLOGY
The bioretention cell was sized using the current NCDENR spreadsheet and methodology. The
USDA Soil Conservation Service's Soil Survey of Forsyth County, North Carolina2 (Soil Survey)
was used to determine the existing soil group dassifications. Soils present on this site have a
hydrologic soils group classification of `B'.
The site is currently undeveloped, however, it was used as farmland in the past, a composite pre-
developed rational coefficient of 0.35 was calculated the drainage area to Bio-Cell No. 2, and
0.35 for the drainage area to Bio-Cell No.3. The composite post-developed managed coefficient
of 0.69 and 0.63 for Bio-Cells 2 and 3 respectively, was calculated based on the impervious
coverage of the proposed roadway. Coefficient calculations with references are included in the
appendices.
Rainfall data used in the hydrologic analysis for the project was taken from Technical Paver No.
40 - Rainfall Frequency Atlas of the Unites States4 (TP-40), published by the U.S. Department of
Commerce.
Hydrographs were computed using the Rational Method.
Pipe flow out of the stormwater management system was calculated under both inlet and outlet
control, and the lesser of the two outflows taken as the control- A weir coefficient of 3.33 was
useU.
Storm hydrograph routing through the device was performed using the Storage Indication'4lethod
as outlined in NEH-4. A brief summary of the routing results is included at the end of this
narrative. Detailed routing calculations are included in the appendices.
SYSTEM CONFIGURATION
The stormwater management devices proposed for this project are bioretention cells for water
quality treatment. Due to the concentrated flow into the device, forebays will be provide for
pretreatment and energy dissipation, while plunge pools will provide the required outfail energy
dissipation and some sheet flow into the buffer area.
The cell layers will consist of 2" hardwood mulch, 2 feet soil planting media, 4 inch washed sand
and 8 inch washed stone, with a total depth of 3.17 feet. Treatment surface areas required and
provided are as follows-
BIO-CELL No. DRAINAGE PERCENT SURFACE AREA SURFACE AREA
AREA I IMPERVIOUS I REQUIRED ( PROVIDED
I
2 4.80 ac_ 56.9'-/ ! 9,794 SF I 10,3$0 SF
3 ! 5-£3 ac- 79.3% " 15.608 SF ! 15,$42 SF
Seasonal high water table investigation was conducted. The SHVVT in the area the devices are
proposed was found to be 9 feet below the surface for Bio-cell No. 2, and 7 feet for Bio-Cell No.
3, both areas are found to be adequate for installing the devices. The outfatt of the ceas will be a
6' underdrains flowing into a 4 sided yard inlet with a 24 inch barrel outlet. The bioretention cells
will have a 12 inch ponding depth. Flows above the ponding level will be controlled by the yard
inlet. Here is a summary of the control elevations:
BIO-CELL No. 2
BIO-CELL No. 3
Control Point Elevation
Riser barrel invert 916.65
LRle.r _ I 7
Top of Riser 922.58
Device Bottom 920.75
Top of dam ; 922.00
The system will not provide peak attenuation to pre-development levels per Town of Kernersville
r ey?nir pments. Design ?omputati. nS follow this, narrativa.
REFE=RENCES
('I) Sof( Survey of Forsyth County, Norf1 Carolina, USDA Soff Conservation Service,
May 1975
(2) National Engineering Handbook Section 4-Hydrology, USDA Soil Conservation Service, 1972
(3) Technical Paper No. 40 - Rainfall Frequency Atlas of the Unites States for Durations from 30
Minutes to 24 Hours and Return Periods from 1 To 900 Years, US. Department of
Commerce, May 1961
BIORETENTION CELL CALCULATIONS
Permit Number.
(to be provided by DWQ)
C)` It;-A , 9
DU)a
w.
MCDENR
STORMIUVATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BPOR- E JENTI M 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.
I. PROJECT INFORMATION
Project name Kernersville Medical Parkway
Contact name Omar Ching, PE
Phone number 336-7231067
Date February 12, 2009
Drainage area number Bio Cell #2
Ii. DESIGN INFORMATION
Site Characteristics
Drainage area 208,950 ft'
Impervious area 118,800 ftz
Percent impervious 56.9% %
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 ft/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 9,794.0 ft3
Volume provided 10,380.0 ft3 OK
Storage Volume: SA Waters
1.5" runoff volume ft 3
Pre-development 1-yr, 24-hr runoff ft3
Post-development 1-yr, 24 hr runoff ft3
Minimum volume required 11
0 ft3
Volume provided W
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 10,380.0 ft` OK
Length: 150 It OK
Width: 70 ft OK
-or- Radius It
Media and Soils Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown time, '-)al: 48 hr
In-situ soil'
Permeability 1.00 in/hr OK
P "doting
P"do!ting i--nedia So""r
Soil permeability 1.00 in/hr OK
Soli com;inosi_
% "''arid ibl weiy'iii ui ib -nK
% Fines (by weight) 9% OK
Orcanic Ibv weight; 4% OK
Forri S4V401 -Bioretention-Rev.7 Total 100%
Parrs 1 and 11 Design Summary. Page 1 of 3
Permit ^lumbec
(to be provided by DWQ)
Phosphorus Index (P-Index) of media 20 (unit?ess) OK
Form SW401 -Bioretention-Rev. 7 Parts I and II. Design Summarv, Page 2 of 3
Permd "dumber
(to be provided by DWQ)
Basin !E#evatlons
Temporary pool elevation 888.75 fmsl
Type of bioretention cell (answer "Y" to only one of the two following
-estions
is this a grassed cell? Y (Y or N) OK
Is this a cell with trees/shrubs? N (Y or N)
Planting elevator, (fop of the mulch or grass sod layer' Rg7 74 fi,s!
Depth of mulch inches
Bottom of the planting media soil 885.75 fmsl
Planting media depth 2 it
Depth of washed sand below planting media soil 0.25 ft
Are underdrains being instalied? Y (Y or N)
How many clean out pipes are being installed? 27 OK
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.8) 2 OK
Additional distance between the bottom of the planting media and the
bottom of the cell to account for underdrains 1 it
Bottom of the cell required 884.5 fmsl
SHWT elevation 882.5 fmsl
Distance from bottom to SHWT 2 It OK
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? 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 filer? 30 ft
Does the design use a level spreader to evenly distribute flow? Y (Y or N) Submit a level spreader supplement
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) fdsec
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
(81inches gravel followed by 3-5 it of grass)
Grassed swale OK
Forebay X
011Sa
Form SW401-Bioretention-Rev 7 Parts 1 and 11. Design Summary. Paae 3 of 3
RiPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET (Version 8.99)
(Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
JOB:
DESIGNER:
CHECKER.
INPUT DATA:
Conduit Diameter
Conduit Discharge-
Conduit Slope at Outlet:
Conduit Outlet Invert Elevation-.
Tailwater Elevation:
Outlet Channel Invert Elevation:
.... .....
--
Water Density:
Bed/Riprap Particle Density: (Default 2.64)
D, 50 Riprap Size:
Riprap Thickness: (2.5*D, 50 recommended)
Bedding Thickness: (6 inch min. rec.) (Enter 0 for geotextile)
Side Slope Ratio:
Upstream End Slope Ratio:
Downstream End Slope Ratio:
Combined End Slope Patio:
OUTPUT-POOL LOCATION AND DIMENSIONS:
Vert. Dist. from Tailwater to Conduit Invert:
Submergence Check: of Zp < 0, Use Zp = 0)
Beaching Check: [Q/(gD^5)^0.5 <_ (1.0+25*D,50/D)]
"Beaching Controlled**
Distance from Conduit Exit to C/L Pool:
Pool depth at C/L Below Conduit Invert:
Pool Bottom Elev:
Poo! Bottom Length:
Pool Bottom Width:
Upstream Pool Length at Tailwater Elev.:
Downstream Pool Length at Tailwater Elev.:
Pool Width at Tailwater Elev.:
Check Side Slope Ratio: (Wr>=We)
"Side Slope Ratio Zw O.K.**
Check Min. End Slope Ratio: (Lru & Lrd >= Le)
**End Slope Ratios O.K.**
Chick Upstream Length: (Lru - Xrn)
**End Slope Ratio Zlu O.K.*"
Pool Bottom Elev. at Bottom of Riprap:
Pool Bottom Elev. at Bottom of Bedding:
OUTPUT--VOLUMES BELOW WATER SURFACE ELEVATION:
Volume of Excavations (measured frrm bottom
surface of bedding):
Volume of Rock Riprap:
-.rea of Geote.Aie:
Date: 6/1/2009
Dale.
D ft
Q = cfs
S= ft/ft
El, C0 = ft
El, TW = r . _ . ft
El, CH = _ ft
1.00
2.64
ft
ft
ft
ft'ft
Rift
w ft/ft
2.00 ft/ft
RHO =
RHOS =
RS =
RT =
BT =
Zw =
Zlu =
Zld =
71 =
1.00 ft
1.00 ft
O.K.
Zp =
Use Zp =
Xm =
Zp+0.8Zm =
EI,PB =
21A =
2Wr2 =
Lru =
Lrd =
2Wr =
3.09
3.75
875.75
2.34
2.19
6:67
6.67
13.20
O.K.
ft
ft
ft
ft
ft
ft
ft
ft
O.K.
O.K.
El; SR = 874.50 ft
El, BB = 874.50 ft
20.6 cu yd
13.5 cu yd
52.5 sq yd
V,pbs =
V, rs =
A,gt =
Spreadsheet deveioped by D. HuiiL; lvlidrVest `?Tv, 1, id
Spreadsheet modified by M. Dreischmeier, Eau Claire TC, Wis., 3/98
_D°eslig i Note N1o 6- (Second F:ii+inn) !;;r.,. 23,'986'
RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET
I Reference Desian Note No. 6 (Second Edition), ,Jan. 28, 1986 I
i
Elev. 879.5 _Elev.
I
77 % 878.5
Elev.
3.8 875.7 ii
i L_ 2.3
2.0 2.0
3.1
SECTION A-A
• 18.8
132
i ?
.
f 12
1.3 2.0
I
2.8-? SECTION B-B
I
#
A I i
1 /11 ITI 1-T p1mr .. ..
1
ROCK GRADATION
% Passing Size (in) B
# 100 12 1 f
60-85 9 i1 1 LANDOWNER
25-50 v I
5-20 ( 3 IDESIGNER:
0-5 1 1,2 I VNEET OF
Hydr®rgraph Report
aydraflaw Hydragraphs by {ntelisolve v9.1
Hyd. No. I
Biocell #2
Hydrograph type = Rational
Storm frequency = 10 yrs
Time interval = 1 min
Drainage area = 4.800 ac
Intensity = 5.756 in/hr
OF Curve = Forsyth. iDF
Q (cfs)
21.00
18.00
15.00
12.00
9.00
6.00
3.00
n nn
U.Vi1 -
0 2 4 6
Hued No.
.7
Thursday, An 4, 2009
Peak discharge = 19.06 cfs
Time to peak = 10 min
Hyd. volume = 11,437 cuft
Runoff coeff. = 0.69
Tc by User = 10.00 min
Asc/Rec limb fact = 1 /1
Biocell #2
Hyd. No. 1 -- 10 Year
i
I
I
,
I
% t ;
i
I i
I
I
I \I
j ?
i I
Q (cfs)
- 21.00
- 18.00
- 15.00
- 12.00
- 9.00
- 6.00
- 3.00
- 0.00
10 12 14 16 18 20
Time (min)
Hydrograph Report
Hydrafiow Hydrographs by intelisolve v9.1 Thursday, Jun 4, 2009
Hyd, No. 2
Rat. Route
Hydrograph type = Reservoir Peak discharge = 1.199 cfs
Storm frequency = 10 yrs Time to peak = 19 min
Time interval = 1 min Hyd. volume = 965 cuft
Inflow hyd. No. = 1 - Biocell #2 Max. Elevation = 888.82 ft
Reservoir name = Biocell #2 Max. Storage = 11,238 cuft
Storage Indication method used.
Q (cfs)
21.00
18.00
15.00
12.00
9.00
6.00
3.00
;. vO
Rat. Route
Hyd. No. 2 - 10 Year
C 10
Hyd N -,2
30
40 r >n 60
_ Total storage used 1;238 cuft
Q (cfs)
T21.00
18.00
i
15.00
12.00
9.00
-- 6.00
i
+ 3.00
i
0.00
70
Time (min)
Pdnd Report 2
N jr?r;r, 1=vrlrnnra he by inio{i5 nivF v9 I
-.,
e, in A
Pond No. 1 - Bioce.i #2
Pond Data
Contours - --- r-jefincd contour ar eas. < o??ic me'th0d LIS-—! for ygjuci?- raintliaiiv,n. Benjring Ftavaiinn = _,pjZ
Stage 1 Storage Table
Stage (ft) Elevation (ft) Contour area (sgft) Incr. Storage (cuff) Total storage (cult)
0.00 887.75 9,837 0 0
0.25 '3_--_n0 9 0 - 52 2,498 2,498
1 ?f 888.75 1'x,120 7,97"s ?0,472
2.25 890.00 11,450 14,104 24,575
Culvert ! Orifice Structures Weir Structu res
[A] [B] [C] [PrfRsrl [A] [B] [C] [D]
Rise (in) = 30.00 0.00 0.00 0.00 Crest Len (ft) = 15.00 0.00 0.00 0.00
Span (in) = 30.00 0.00 0.00 0
.00 Crest El. (ft) = 888.75 0.00 0.00 0.00
No. Barrels = 1 V V ,
{
0 Weir Coeff. = 3.3, 3.33 J.3J 11
Invert €l. (ft) = 383.5 0.00 0.00 0.00 Weir Type = user --
Length (ft) = 46.00 0.00 0.00 0.00 Multistage = Yes No No No
Slope (%) = 0.33 0.00 0.00 ria
N-Value = .013 .013 013 n131
Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000 (by Contour)
Multistage = n/a No No No TW Elev. (ft) = 0.00
NoW CulveWOriiice = ut!lo.Ns are inal,zed under Inlet (c; and o
Stage / Storage l Discharge Table uter (oc) mntro!. VVeir risefs choked for oncce conditions (ic; am sumnergerce s;.
Stage Sturage Elevation. Civ A C!v a Clv C PrfRsr 9Wr A Wr a Wr C Wr O Exfil User Total
It cuff ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
0.00 0 887.75 0.00 - --- -- 0.00 - -- --- --- --- 0
00
n 25 2,498 &38.00 37.81 oc - - - 0.00 .
- - - - - ,
Or
1.GG
1 10,472 888.75 37.81 G% -- -- --- 0
00 .
---
2.25
24,576
890.00 51.19 is - - - .
51.19S --- ---
V.
--- - - - - 51.19
Permit Number.
(to be provided by DWQ)
G`• v
v
DENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
mi '17
This iurm must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Kernersville Medical Parkway
Contact name Omar Ching, PE
Phone number 336-723-1067
Date February 12, 2009
Drainage area number 6i0 Ca11-1 3
111. DESIGN INFORMATION
Site Characteristics
Drainage area 245.242 ftz
Impervious area 194,389 ftz
Percent impervious 79.3% %
Design rainfall depth 10 inch
Peak Flow Calculations
Is prelpost 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 irdhr
Pre-development 1-yr, 24-hr peak flow ft3lsec
Post-development 1-yr, 24-hr peak flow ft3lsec
Pre/Post 1-yr, 24-hr peak control ft3lsec
Storage Volume: Non-SA Maters
Minimum volume required 15,608.0 ft3
Volume provided 15,842.0 ft3 OK
Storage Volume: SA Waters
1." 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 15,842.0 ft` OK
Length: 178 f t OK
Width: 89 ft OK
-or- Radius ft
Media and Soils Summary
Drawdown time, ponded volume 12 hr OK
Drawdown time, to 24 inches below surface 36 hr OK
Drawdown hrne Oita;: 48 hr
In-situ soil:
Soil permeability 1.00 in/hr OK
Planting rea1a 3011:
Soil permeability 1.00 in/hr OK
Sci! comcositicn
* Sand,
b lveiyiiu
o;
vi c
vi
Fines (by weight)
9% i
OK
% nr a_ nir_ nhV we;nht ,4-115 ?K
v
Form S1h401-Bicreter;ion-Rev. Total: 100%
Parts I arc li. Design Summary, Page 1 of 3
Perm Number
(b be provided by DWQ)
Phosphorus Index (P-Index) of media
20 (unitless) OK
Form SW401 -Bioretenbon-Rev. 7 Parts I and IL Design Summary. Paqe 2 of 3
aermlt Nualber
(to be Provided by DWQ)
aasin Elevations
Temporary pool elevation 921.75 frrsl
Type of bioretention cell (answer "Y" to only one of the two following
questio'ns):
is this a grassed cell? Y (r or N)
Is this a cell with trees/shrubs? N (Y or N)
Planting elevation (top of the mulch or grass sod layer) 920.75 fms!
Depth of mulch inches
Bottom of the planting media soil 918.75 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)
OK
How many clean out pipes are being installed? 27 OK
What factor of safety is used for sizing the underdrains? (See
BMP Manual Section 12.3.6)
2
OK
Additional distance between the bottom of the planting media and the
bottom of the cell to account for underdrains 1 It
Bottom of the cell required 917.5 fms!
SHWT elevation 913 fms!
Distance from bottom to SHWT 4.5 ft OK
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? 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? 30 ft
Does the design use a level spreader to evenly distribute flow? Y (Y or N) Submit a level spreader supplement.
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) fusec
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
(flinches gravel followed by 3-5 It of grass)
Grassed swaie OK
Forebay
X
then
-orm SVV401-Biorete.ntion-Rev.7
Parts I and II. Design Summary. Page 3 of 3
RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET (Version 8.99)
(Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
JOB.
DESIGNER: Date: 6/1/2009
CHECKER: Date:
INPUT DATA:
Conduit Diameter
Conduit Discharge:
Conduit Slope at Outlet:
Conduit Outlet Invert Elevation:
Tailwater Elevation:
Outlet Channel Invert Elevation:
Water Density:
Bed/Riprap Particle Density: (Default 2.64)
D, 50 Riprap Size:
Riprap Thickness: (2.5*D, 50 recommended)
Bedding Thickness: (6 inch min. rec.) (Enter 0 for cteotextile)
Side Slope Ratio:
Upstream End Slope Ratio:
Downstream End Slope Ratio:
Combined End Slope Ratio:
OUTPUT--POOL LOCATION AND DIMENSIONS:
Vert. Dist. from Tailwater to Conduit Invert:
Submergence Check: (If Zp < 0, Use Zp = 0)
Beaching Check: [Q/(gD"5)^0.5 <= (1.0+25*D,50/D)J
**Beaching Controlled**
Distance from Conduit Exit to C!! Pool:
Pool depth at C/L Below Conduit Invert:
Pool Bottom Elev:
Pool Bottom Length:
Pool Bottom Width:
Upstream Pool Length at Tailwater Elev..-
Downstream Pool Length at Tailwater Elev.:
Pool Width at Tailwater Elev.:
Check Side Slope Ratio: (Wry=We)
**Side Slope Ratio Zw O.K.**
Check Min. End Slope Ratio: (Lru & Lrd >= Le)
'End Slope Ratios O.K.**
Check Upstream Length: (Lrri >= X.m)
**End Slope Ratio Zlu O.K.**
Pool Bottom Elev. at Bottom of Riprap:
Pool Bottom Elev. at Bottom of Bedding:
OUTPUT---VOLUMES BELOW WATER SURFACE ELEVATION:
Volume of EXCaVat on (measured from bo om
surface of bedding;.
Volume of Rock Riprap:
Aria of Gsote.4le:
D= ft
Q = cfs
S = ft/ft
El, CO = = It
El, TW = ft
El, CH = . , ft
RHO = 1.00
RHOS = 2.64
RS = - - ft
RT= ft
BT = It
Zw = ft/ft
Zlu = ft'ft
Zld = ?. - ft/ft
Z1 = 2.00 ft/ft
Zp = 1.00 ft
Use Zp = 1.00 It
O.K.
Xm =
Zp+0.8Zm =
EI,PB =
2Lr2 =
2Wr2 =
I ru =
Lrd =
2Wr =
5.29
5.30
874.20
3.85
3.50
10.53
10.53
20.71
O.K.
ft
It
ft
It
ft
It
ft
It
O.K.
O.K.
El, BR = 872.95 It
El; BB = 872.95 It
V,pbs = 57.0 Cu yd
V,rs = 29.1 cu yd
A,gt = +
98.6 sq yd
Spreadsheet developed by D. Hurt-, Midwest NTC, 1'90
Spreadsheet modified by M. Dreischmeier, Eau Claire TC, Wis., 3/98
Design Note No. 6 (SaGQnd Ed't'on). _ia 2' 1986
RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET
Reference Design Note No. 6 (Second Edition), Jan. 28, 1986
Elev. 879.5 -Elev.
878.5
: Elev.
5.3 I 874.2
2.0 2.0
?-- 4.4 --?
' 5.3 -
I 10.5 -"' 13.3 ---?i
I SECTION A-A
26.3
20.7
3.5 -. 1
1.3 2.0
--- 4.1-? SECTION B-B
I (
A A
I l
II !
ROCK GRADATION
•% Passing Size (in) g j
! 100 12 I I
I i
0-85 f 6 f LANDOWNER
6
25-50
5-20 ( 3 I DESIGNER: I
0-5 I 12 ?z I
SHEET 01
Hydrograh Report
Hydrat1ow Hydrographs by Inteiisohre Al
Hyd. No. I
Biocell #3
Hydrograph type = Rational
Storm frequency = 10 yrs
Time interval = 1 min
Drainage area = 5.630 ac
Intensity = 5.756 in/hr
OF Curve = Forsyth.IDF
Q (cfs)
28.00
24.00
20.00
16.00
12.00
8.00
4.00
0.00 -
n 2 4 6
LSy ' N 3
Thursday, Jun 4, 2009
Beak discharge = 26.90 cfs
Time to peak = 10 min
Hyd. volume = 16,137 cuft
Runoff coeff. = 0.83
Tc by User = 10.00 min
Asc/Rec limb fact = 1/1
Biocell #3
Hyd. No. 1 -- 10 Year
I /
j
`. I
r
I
8
Q (cfs)
28.00
24.00
20.00
16.00
12.00
8.00
4.00
2 ^ ' y 1 ?- 0.00
8 0
Time (min)
Hydrograph Report
Hydrafcw Hydrographs by inteiiscive v9.1 Thursday; Jun 4. 2009
Hyd. No. 2
Rat. Route
Hydrograph type = Reservoir Peak discharge = 7.062 cfs
Storm frequency = 10 yrs Time to peals = 17 min
Time interval = 1 min Hyd. volume = 5,186 cuft
Inflow hyd. No. = 1 - Biocell #3 Max. Elevation = 922.02 ft
Reservoir name = Biocell #3 Max. Storage = 14,155 cuft
Storage indication method used
Q (cfs)
28.00
24.00
20.00
16.00
12.00
8.00
4.00
0.00
1v 20 vJ
Hyd I:o. 2 - ;4yd No.
Rat. Route
Hyd. No. 2 -- 10 Year
40 `7U an ! V
S=oraye 11 sed _ 14,+65
Q (cfs)
28.00
24.00
20.00
16.00
12.00
8.00
4.00
0.00
VN
Time (min)
Fond Report
2
Hydrafiow Hyn_',r. graphs by :r!te!I__ soiwe ;:Q 1 _ Thirgfiav Ain 4_ 2Q11?
Pond No. - B.--Cell #3
Pond Data
Contours - User_de ined contour areas v nic. met`nd used for volume alcu!a,;on Oegining elevation = 920 75 ft
Stage / Storage Table
stage (ft`. Elevation (ft) Contour area dsgft) Incr. Storage (cuff) Total storage (cuff)
0.00
? 920.75 10,276 0 0
5
0 a"1.00
-0
,610
'
2,610
2
610
1.GO 921. ;
1 ,63? 8,339 ,
10 950
1.25 922.00 11,990 2,953 13
903
3.25 924.00 17,620 29,427 ,
43,330
Culvert I Orifice Structures Weir Structures
[A] [B] [C] [PrFRsr] [A] [B] [D] [D]
Rise (in) = 30.00 0.00 0.00
C.CC
Crest Len (ft)
= 15.13
0.00
0.00
0
00
Span (in) = 30.00 0.00 0.00 0.00 Crest Et. (ft) = 921.75 0.00 0.00 .
0.00
No. Barrels = 1 0 I 0 Weir Coeff. = 3.33 3.33 3.33 3
33
Invert El. (ft) = 916,55 0.00 0.00 0.00 Weir Type = Riser --- .
Length (ft) = 34.00 0.00 0.00 0.00 Multistage = Yes No No No
Slope (%) = 0.34 0.00 0.00 n/a
N-Value = 0013 O 13 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60 ExtIL(in/hr) = 0.000 (by Contour)
Multistage = rVa No No No TW Elev. (ft) = 0.00
wo,e GulvertiQn?jre Mjttiows are analyzed uncle
Stage / Storage / Discharge Table , Inlet `rr.) and outlet iori rnntrol. Weir n5 meow ry_ for ontlre ronaieons `irk ana suDm rngenre isi.
Stage Storage Elevation
It Civ A CIv B Clv C PrfRsr Wr A Wr B Wr C Wr Q Exfil User Total
cuff ft cis cfs cfs cfs cfs cis cfs cfs cfs cfs cfs
0-00 0
920.
7
5 0.00 --- 0
00 --
?
(^
t
-5 L,61 J 921 .?.r1:
38.- Vc
--- - .
--- 0
1. --
__- 0.00
1.00 10,950 921.75
38.33 oc
- - .
-- 0
00
-
-- 4.VU
1.25 13.903 922.00
38.33 oc
-- -- .
--- 6
30
- -
--
-- - 0.00
3.25 43;330 924.00
57.92 is
- .
- 57
91
s 6.30
. 57.91
SEASONAL HIGH WATER TABLE EVALUATION
REPORT
i
CD
?A2@2'1 ?? aoiA?
ECS CAROLINAS, LLP
Ocotechnicai ® Construe-tion Materials' Environmental
March 16, 2009
Mr. Hank Perkins
Trade Street Development Corporation
807 North Trade Street
Winston Salem, North Carolina 27101
Reference: Report of Seasonal High Water Table Determination
Kernersville Medical Parkway
Kemersville, North Carolina
ECS Project 09-17129
Dear Mr. Perkins:
ECS Carolinas, LLP (ECS) is pleased to provide you with our Report of Seasonal High Water
Table (SHWT) Determination for three proposed bio-retention cells adjacent to the proposed
Kemersville Medical Parkway in Kemersville, North Carolina. Our services were provided in
general accordance with ECS Proposal No. 09-14810-P.
PROJECT INFORMATION
The three bioretention cells are located adjacent to the proposed Kernersville Medical Parkway.
Two proposed bio-retention cells are located south of Brookford Industrial Drive adjacent to an
unnamed tributary to the Deep River. The third bio-retention cell is located just west of the West
Fork Deep River off of Macy Grove Road.
SCOPE OF SERVICES
ECS has conducted an investigation of the soils to determine the seasonal high water table in the
area of the three bio-retention cells. Soil borings were drilled with a hand auger to a depth of 108
inches (two feet below the bottom of the bio-retention cells), observation/determination of the
seasonal high water table, or auger refusal. The soil properties and characteristics were observed
and recorded in field notes. The properties include texture, depth, slope, the presence of restrictive
horizons, depth to seasonal high water table, coarse fragments, etc.
The assessment was conducted in accordance with current soil science practices and technology
and the North Carolina Division of Water Quality Stormwater Hest Management Manual July, 2007.
The locations of the borings are depicted on a site sketch provided by Stimmei Associates, P. A.
Seasonal High Water Table Determination
Bio-Retention Cell A
Boring Al (Red; The surface layer has textures of sandy clay loam, clay loam, and sandy loam to a
depth of 36 inches. The structure is massive with friable to firm, slightly sticky, plastic consistence,
"_ _ n - ;I - - -1
u.n i ,„r?r i2fli7iaS7'a 1`ri ad:rs+r n.i-.-'- !'ti9 iii, 'ai id . z' li?iia i:-ia ..s j..<"7 ii;ia
Seasonal High Water Table Detsrmiratian
Ker>.ers-ville .?I a. .l pa;.,, -'Kernersville, North Carolina
ECG' Project 09-17129
larc.4 16, 2009
The subsurface layer -,, m 36 to 46 inches has a texture of clay. The structure is subanguiar biocky
with firm, slightly sticky to sticky, plastic consistence. The subsurface layer from 46 to 55 inches
has texture of loam. The structure is granular with friable consistence. The subsurface layer from
55 inches to 72 inches has textures of clay loam and sandy loam. The structure appears to be
massive with friable, slightly sticky, slightly plastic consistence. The subsurface layer from 72
inches to 84 inches has textures of clay and loam. The structure appears to be massive with
friable, slightly sticky, slightly plastic consistence. The subsurface layer from 84 inches to 95 inches
has a texture of sandy clay loam. Common, few to medium, distinct gray mottles (10YR 512) were
observed at 84 inches. The structure is massive with friable, slightly sticky, slightly plastic
consistence. The subsurface layer from 95 inches to 108 inches has a texture of sandy clay loam.
The matrix of this layer is gray (10YR 5/2) with yellowish brown mottles. The structure is massive
wi#h friable, slightly sticky, slightly plastic consistence. The slope r anges from 2 to "percent,
Borinc A2 (Red) The surface layer has a texture of loam, 15 inches deep. The structure is granular
with friable consistence. The subsurface layer from 15 to 46 inches has textures of clay and sandy
clay loam. The structure is subanguiar blocky with friable, slightly sticky, plastic consistence. The
subsurface layer from 46 to 60 inches has a texture of sandy clay loam. Common, few to medium,
distinct gray mottles (10YR 5/2) were observed at 46 inches. The structure is massive with friable,
slightly sticky, plastic consistence. The subsurface layer from 60 inches to 72 inches has a texture
of sandy clay loam. The matrix of this layer is gray (10YR 5/2) with yellowish brown and yellowish
red mottles. The structure is massive with friable, slightly sticky and slightly plastic consistence.
The slope ranges from 3 to 5 percent.
Bio-Retention Cell B
The surface layer has a texture of loam, 10 inches deep. The structure is granular with very friable
consistence. The subsurface layer from 10 to 20 inches has a texture of sandy clay loam. The
structure is subangular blocky with friable to firm, slightly sticky to sticky, plastic consistence. The
subsurface layer from 20 to 29 inches has textures of clay loam and sandy loam. Common, few to
medium, distinct gray mottles (10YR 5/2) were observed at 18 inches. The structure is massive
with friable consistence. The subsurface layer from 29 inches to 40 inches has textures of clay
loam and sandy loam. The matrix of this layer is gray (10YR 5/2) with yellowish brown and
yellowish red mottles. The structure is massive with firm, slightly sticky to sticky and plastic
consistence. The slope ranges from 2 to 4 percent.
Bio-Retention Cell C
The surface layer has a texture of loam, 5 inches deep. The structure is granular math very friable
consistence. The subsurface layer from 5 to W inches has a texture of clay. The stricture is
subanguiar blocky with friable, slightly sticky, slightly plastic consistence. The subsurface layer
from 30 to 50 inches has textures of day and clay loam. The structure is subangular blocky with
friable, slightly sticky, slightly plastic consistence. The subsurface layer from 50 inches to 108
inches has textures loam and sandy clay loam. The structure is massive with friable consistence.
The slope ranges from 4 `o 6 1m-ent
Seasonal High Water Table Determination
' Kernersville A3edical Parkway
Xernersville, !North Carolina
ECS Project 09-17129
iwfarc: 1K
, ?nn9
Conclusions
Bio-Retention Cell A
Two borings were drilled in the area proposed for the bio-retention cell designated in this report as
Cell A. Boring Al was drilled in the area where fill was observed. The seasonal high water table
was found at 84 inches as indicated by the presence of common, fine to medium, distinct gray
(10YR 512) mottles. The layer from 95 to 108 inches had a matrix color of gray (10YR 5/2). The
second boring, A2 was drilled in an undisturbed area adjacent to the area with fill. The seasonal
high water table was found at 48 inches as indicated by the presence of common, medium, distinct
gray (IOYR 5/2) mottles. The layer from 60 to 72 inches had a matrix color of gray (10YR 5/2).
Bio-Retention Cell B
The seasonal high water table was found at 20 inches as indicated by the presence of common,
fine to medium, distinct gray (1 OYR 5/2) mottles. The layer from 29 to 40 inches had a matrix color
of gray (1 OYR 5/2).
Bio-Retention Cell C
The seasonal high water table was found to be greater than 108 inches.
CLOSING
ECS is pleased to offer you our professional services and we look forward to assisting in any of
your site analysis needs in the future. If you have any questions or require further assistance,
please contact us at (336) 8 X50.
Respectfully,
ECS CAROLINA
9?29dd
Joseph A. Hintoi
Senior Soil Sciei
Cc: Omar Ching
SOIL
G ?Q H A. yfM ?,
oy ??v Ao
Denise M. Poulos, LSS
Principal Scientist
Attachments: Figure 1 - SHWT - Bio-Retention Cell A & B
Figure 2 - SHWT - Bio-Retention Cell C
^TTr,.
?,{ END.
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DRAINAGE AREA EXHIBIT
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° Exhibit II
`.
ISO
10,000
168 8,000 EXAMPLE
156 6000 D-42 Inches (3.3 teat) 6
144 5,000 0•120 Ste 6.
132 4,000 Al A mw 6• 5.
3,000 D Poor 5 4.
120 (1) 2.5 0.8
2,000 (2) 2.1 7.4
108 (3) 2.2 7.7 4.
3.
96 °D in feet
1,000 3•
800
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600
500
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Z N / N
60 U.
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)
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10
P 8
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6 .7
4.
3.
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To use 1:010 (2) or (3) project
21 5 horizontally to Scale (1) then
4 use straight Inelined line through
D and 0 scales. or reverse as 6
3 illustrated. e 6
IS
5
1.0 .5
.5
12 HEADWATER DEPTH FOR
HEADWATER SCALES 2813 CONCRETE PIPE CULVERTS
BUREAU OF Pi LICROAOSJAl0.1943 REVISED MAY 1964 WITH INLET CONTROL
VI-11
Appendices
? ! ?'?Illf II ???
Owlet
W ? D0 + L3 9? - _ -- -?---- I. III E?
d?amatsr i
(Do) ?d _? 80 I III,I!I ??
T ilwater < 0. 5D'
i Ir ill.l
ra I
I;, I t .. I_ i I I ? I
I I III; I I , ' „ I,.
(?`\•a I III III f .. i !I f l is a {` f ! II
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ve
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