SW8080937_APPLICATION_20080826

Benton Ready Mix of Brunswick
HYDROLOGY & HYDRAULIC
CALCULATIONS
SECTION I
"PRE" & "POST" Development Conditions
SECTION II
STORMWATER POND
SECTION III
EROSION CONTROL
September 2008
Compass .Pointe Engineering, PA
Ocean Isle Teach, NC

SECTION I
"PRE" & "POST' Development Conditions

Sri{,-o01
JVA-01
s,or r �r
z •S
o— o
(7- 4t, 'fio%,Z »s)
c' r
c
�,?7 !7 ..J �;•r,.. ar�. /a�I it n�„ ..� `�i
4 C
SC/0'O = SSA CSCIP 07<t,Cgt5)�CL00;
8000' ='7i
V
. �.r cj ._i • `%�`"'c� . I`% � �" yn.aY 1' ,ry f'" "gyp- v�'� Q. r.,,p% v n , I� ��"i .y Q

)nal Formula
:and=uses„-�`:
+ �,GValue
0.75-0.95
flat, 2%
0.05-0.10
average, 2-7%
0.10-0.15
steep.7%
0.15-0.20
flat, 2%
0.13-0.17
average, 2-7%
0.18-0.22
steep, 7%
0.25-0.35
and:
soil
0.30-0.60
0.20-0.50
ws
o crop
0.30-0.60
rith crop
0.20-0.50
o crop
0.20-0.40
rith crop
0.10425
0.15-0.45
0.05-0.25
0.05-0.25
date C value within
the range for
able soils, flat slopes, and dense
h slowly permeable soils, steep
alues.
r estimation of the pre -
ration (Tc) and peak
the Town.

C
Hydrograph Return Period Recap
HydraFlow Hydrographs by Intelisolve v9.23
Hy d.
No.
Hydrograph
type
(origin)
Inflow
Hyd(s)
Peak Outflow (cfs)
1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr
Hydrograph
description
1
Rational
----
3.982
--
--
7.375
----
-----
19.06
PRE Conditions
2
Rational
8.761
---
--
16.23
---
----
41.92
POST without Storage
3
Mod. Rational
--
4.930
--
--
9.343
--
21.34
POST Modified for Routing
4
Reservoir
3
0.000
---
5.212
--
---
10.48
POST Routed Q
Proj. file: Benton POST Routed 8-25-08.gpw
Tuesday, Aug 26, 2008

I-4
2
Hydrograph Summary Report
HydraFlow Hvdrooraohs by Inrart„i„o „o 11
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Hyd.
volume
(tuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(tuft)
Hydrograph
description
1
Rational
3.982
1
5
1,195
---
----
--
PRE Conditions
2
Rational
8.761
1
5
2,628
--
--
--
POST without Storage
3
Mod. Rational
4,930
1
5
14,493
--
POST Modified for Routing
4
Reservoir
0.000
1
nta
0
3
41.90
14,493
POST Routed Q
Benton POST Routed 8-25-08.gpw
Return Period: 1 Year
Tuesday, Aug 26, 2008

Hydrograph Report
OF
3
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 1
PRE Conditions
Hydrograph type
= Rational
Peak discharge
= 3.982 cfs
Storm frequency
= 1 yrs
Time to peak
= 5 min
Time interval
= 1 min
Hyd. volume
= 1,195 cuft
Drainage area
= 5.900 ac
Runoff coeff.
= 0.25
Intensity
= 2.700 in/hr
Tc by User
= 5.00 min
OF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
= 1/1
Q (cfs)
4.00
3.00
2.00
1.00
M
PRE Conditions
Hyd. No. 1 -- 1 Year
Q (cfs)
4.00
3.00
2.00
1.00
0 00
0 1 2 3 4 5 6 7 8 9 10
— Hyd No. 1 Time (min)

4
Hydrograph Report
HydraFlow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 2
POST without Storage
Hydrograph type = Rational
Peak discharge
= 8.761 cfs
Storm frequency = 1 yrs
Time to peak
= 5 min
Time interval = 1 min
Hyd. volume
= 2,628 cuft
Drainage.area = 5.900 ac
Runoff coeff.
= 0.55
Intensity = 2.700 in/hr
Tc by User
= 5.00 min
IDF Curve = EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
= 1/1
POST without Storage
Q (cfs) Hyd. No. 2 — 1 Year Q (ofs)
10.00
8.00
6.00
4.00
2.00
000
10.00
8.00
6.00
4.00
2.00
000
0 1 2 3 4 5 6 7 8 9 10
Time (min)
Hyd No. 2

Hydrograph Report 50
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 3
POST Modified for
Routing
Hydrograph type
= Mod. Rational
Peak discharge =
4.930 cfs
Storm frequency
= 1 yrs
Time to peak =
5 min
Time interval
= 1 min
Hyd. volume =
14,493 cuft
Drainage area
= 5.900 ac
Runoff coeff. =
0.55
Intensity
= 1.519 in/hr
Tc by User =
5.00 min
IDF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Storm duration =
9.8 x Tc
Target Q
= 4.000 cfs
Est. Req'd Storage=
7,926 cuft
POST Modified for Routing
Q (cfs) Hyd. No. 3 -- 1 Year
5.00
4.00
Ulm
2.00
1.00
1 11
Q (cfs)
5.00
4.00
3.00
2.00
1.00
0 2 4 6
8
10 12 14
16 18 20
22 24 26 28 30 32 34 36 38 40
42 44 46 48 50 52 54
— Hyd No.
3
; ,.I
' 11J Mod.
Rational Est. Storage = 7,926 curt
Time (min)

Hydrograph Report
Cj
6
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 4
POST Routed Q
Hydrograph type
= Reservoir
Peak discharge
= 0.000 cfs
Storm frequency
= 1 yrs
Time to peak
= n/a
Time interval
= 1 min
Hyd. volume
= 0 cuft
Inflow hyd. No.
= 3 - POST Modified for Routing
Max. Elevation
= 41.90 ft
Reservoir name
= Benton SW Pond
Max. Storage
= 14,493 cuft
Storage Indication method used.
POST Routed Q
Q (cfs)
Hyd. No. 4 -- 1 Year
5.00
4.00
3.00
2.00
1.00
XM
Q (cfs)
5.00
4.00
3.00
2.00
1.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54
Time (min)
— Hyd No. 4 —Hyd No. 3 11..1
i' " Total storage used = 14,493 tuft

Pond Report
7
Hydrallow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Pond No. 1 - Benton SW Pond
Pond Data
Contours - User -defined contour areas. Average end area method used for volume calculation. Begining Elevation = 41.00 If
Stage I Storage Table
Stage (ft) Elevation (ft) Contour area (sgft)
Incr. Storage (tuft)
Total storage (tuft)
0.00 41.00 13,399
0
0
0.50 41.50 16,908
7,577
7,577
1.00 42.00 17,988
8,724
16,301
1.20 42.20 18,428
3,642
19,942
2.00 43.00 20,202
15,452
35,394
3.00 44.00 22,467
21,335
56,729
4.00 45.00 24,794
23,631
80,359
Culvert I Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 18.00
0.00
0.00
0.00
Crest Len (ft)
= 12.00
0.00
0.00
0.00
Span (in)
= 18.00
0.00
0.00
0.00
Crest El. (ft)
= 42.20
0.00
0.00
0.00
No. Barrels
= 1
0
0
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft)
= 39.00
0.00
0.00
0.00
Weir Type
= Recl
-
-
_
Length (ft)
= 250.00
0.00
0.00
0.00.
Multi -Stage
= Yes
No
No
No
Slope (%)
= 0.44
0.00
0.00
n/a
N-Value
= .013
.013
.013
n/a
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfil.(inlhr)
= 0.000 (by Wet area)
Multi -Stage
= n/a
No
No
No
TW Elev. (ft)
= 0.00
Stage If)
4.00
Elm
2.00
1.00
0.00
Note'. CUNCNOMce oull!"s are analyzed under inlet (ic) and outlet (m) control. N%u rime rh W for orifm conddions (ic) end wbmergenw (s).
Stage I Discharge
Elev (ft)
45.00
44.00
43.00
42.00
41 00
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00
Total 0 Discharge (cfs)

Hydrograph Summary Report
Hydraflow H dr h
8
I%
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs )
Time
interval
(min)
Time to
peak
(min)
Hyd. Inflow
volume hyd(s)
(tuft)
Maximum Total
elevation str a used
9
(k) (cuk)
y ograp s by Intelisolve va.zz
Hydrograph ,
description
1
Rational
7.375
1
5
2,213
--
--
---
PRE Conditions
2
Rational
16.23
1
5
4,868
--
-
---
POST without Storage
3
Mod. Rational
9.343
1
5
27,468
--
POST Modified for Routing
4
Reservoir
5.212
1
51
7,524
3
42.46
24,891
POST Routed Q
I
i
r
Benton POST Routed 8-25-08.gpw
Return Period: 10 Year
Tuesday, Aug 26, 2008

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 1
PRE Conditions
Hydrograph type
= Rational
Peak discharge
= 7.375 cfs
Storm frequency
= 10 yrs
Time to peak
= 5 min
Time interval
= 1 min
Hyd. volume
= 2,213 cult
Drainage area
= 5.900 ac
Runoff coeff.
= 0.25
Intensity
= 5.000 in/hr
Tc by User
= 5.00 min
OF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
= 1/1
Q (cfs)
8.00
M
4.00
2.00
PRE Conditions
Hyd. No. 1 — 10 Year
Q (cfs)
8.00
4.00
2.00
0.00 z I L I I I I I I I \I. 0.00
0 1 2 3 4 5 6 7 8 9 10
— Hyd No. 1 Time (min)

Hydrograph Report
Hyaranow Hyarographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 2
POST without Storage
Hydrograph type = Rational
Peak discharge
= 16.23 cfs
Storm frequency = 10 yrs
Time to peak
= 5 min
Time interval = 1 min
Drainage area = 5.900 ac
Hyd. volume
= 4,868 cuft
Intensity = 5.000 in/hr
Runoff coeff.
Tc by User
= 0.55
= 5.00 min
IDF Curve = EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
=. 1/1
Q (cfs) POST without Storage
Hyd. No. 2 — 10 Year Q (cfs)
18.00
15.00
12.00
9.00
6.00
3.00
0.00
18.00
15.00
12.00
9.00
6.00
3.00
000
u 1 2 3 4 5 6 7 8 9 10
Hyd No. 2 Time (min)

Hydrograph Report
Hydrafiow Hydrographs by Intelisolve v9.23
Hyd. No. 3
POST Modified for Routing
Hydrograph type
= Mod. Rational
Storm frequency
= 10 yrs
Time interval
= 1 -min
Drainage area
= 5.900 ac
Intensity
= 2.879 in/hr
IDF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Target Q
= 7.400 cfs
Tuesday, Aug 26, 2008
Peak discharge = 9.343 cfs
Time to peak =
5 min
Hyd. volume =
27,468 cuft
Runoff coeff. =
0.55
Tc by User =
5.60 min
Storm duration =
9.8 x Tc
Est. Req'd Storage=
15,295 cuft
POST Modified for Routing
Q (cfs) Hyd. No. 3 — 10 Year
10.00 .—�.
:M
. 11
4.00
2.00
I e,
Q (cfs)
10.00
�1
4.00
2.00
0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54
Time (min)
— Hyd No. 3 1'.I ; ' 1 Mod. Rational Es[. Storage = 15,295 tuft

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.23
Hyd. No. 4
POST Routed Q
Hydrograph type
= Reservoir
Storm frequency
= 10 yrs
Time interval
= 1 min
Inflow hyd. No.
= 3 - POST Modified for Routing
Reservoir name
= Benton SW Pond
Storage Indication method used
Q (cfs)
10.00
: 11
Am
CX4►1
2.00
r 18
POST Routed Q
Hyd. No. 4 — 10 Year
12 3
Tuesday, Aug 26, 2008
Peak discharge = 5.212 cfs
Time to peak
= 51 min
Hyd. volume
= 7,524 cuft
Max. Elevation
= 42.46 ft
Max. Storage
= 24,891 cuft
Q (cfs)
10.00
m
.D1
4.00
2.00
0 00
0 20 40 60 80 100 120 140 160
Time (min)
— Hyd No. 4 —Hyd No. 3 -I ` 7 i Total storage used = 24,891 tuft

�- S
13
Hydrograph Summary Report
HydraFlow Hydro9raohs by Intelisolve v9 93
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
H d.
volu�d(s)
I (Cott)
Inflow ,
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
description
1
Rational
19.06
1
5
5,717
—
---
----
PRE Conditions ,
2
Rational
41.92
1
5
12,577
--
--
—
POST without Storage
3
Mod. Rational
21.34
1
5
39,044
---
----
------
POST Modified for Routing
4
Reservoir
10.48
I
i
1
33
18,460
i
I
3
42.79
31,320
POST Routed 0
I
I
I
Benton POST Routed 8-25-08.gpw
Return Period: 100 Year
Tuesday, Aug 26, 2008

Hydrograph Report
14
HydraRow Hydrographs by Inlelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 1
PRE Conditions
Hydrograph type
= Rational
Peak discharge
= 19.06 cfs
Storm frequency
= 100 yrs
Time to peak
= 5 min
Time interval
= 1 min
Hyd. volume
= 5,717 cuft
Drainage area
= 5.900 ac
Runoff coeff.
= 0.25
Intensity
= 12.919 in/hr
Tc by User
= 5.00 min
IDF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
= 1/1
PRE Conditions
Q Ids) Hyd. No. 1 -- 100 Year Q (cfs)
21.00
18.00
15.00
12.00
9.00
6.00
3.00
0.00
21.00
18.00
15.00
12.00
9.00
6.00
3.00
0.00
0 1 2 3 4, 5 6 7 8 9 10
— Hyd No. 1 Time (min)

Hydrograph Report
15
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 2
POST without Storage
Hydrograph type = Rational
Peak discharge
= 41.92 cfs
Storm frequency = 100 yrs
Time to peak
= 5 min
Time interval = 1 min
Hyd. volume
= 12,577 cuft
Drainage area = 5.900 ac
Runoff coeff.
= 0.55
Intensity = 12.919 in/hr
Tc by User
= 5.00 min
IDF Curve = EC Manual DMC 6-14-08.pcp.IDF
Asc/Rec limb fact
= 1/1
Q (cfs)
50.00
40.00
30.00
20.00
10.00
M
POST without Storage
Hyd. No. 2 — 100 Year
Q (cfs)
50.00
40.00
30.00
20.00
10.00
000
0 1 2 3 4 5 6 7 8 9 10
— Hyd No. 2
Time (min)

Hydrograph Report
16�
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 3
POST Modified for
Routing
Hydrograph type
= Mod. Rational
Peak discharge =
21.34 cfs
Storm frequency
= 100 yrs
Time to peak =
5 min
Time interval
= 1 min
Hyd. volume =
39,044 cuft
Drainage area
= 5.900 ac
Runoff coeff. =
0.55
Intensity
= 6.575 in/hr
Tc by User =
5.00 min
IDF Curve
= EC Manual DMC 6-14-08.pcp.IDF
Storm duration =
6.1 x Tc
Target Q
= 19.00 cfs
Est. Req'd Storage=
18,174 cuft
POST Modified for Routing
Q (cfs) Hyd. No. 3 — 100 Year Q (cfs)
24.00
20.00
16.00
12.00
8.00
4.00
0.00
24.00
20.00
16.00
12.00
8.00
4.00
000
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
Time (min)
— Hyd No. 3 '. I_ !__ Mod. Rational Est. Storage = 18,174 tuft

Hydrograph Report
17 —`
Hydraflow Hydrographs by Intelisolve v9.23
Tuesday, Aug 26, 2008
Hyd. No. 4
POST Routed Q
Hydrograph type
= Reservoir
Peak discharge
= 10.48 cfs
Storm frequency
= 100 yrs
Time to peak
= 33 min
Time interval
= 1 min
Hyd. volume
= 18,460 cuft
Inflow hyd. No.
= 3 - POST Modified for Routing
Max. Elevation
= 42.79 ft
Reservoir name
= Benton SW Pond
Max. Storage
= 31,320 cult
Storage Indication method used.
POST Routed Q
Q (cfs) Hyd. No. 4 -- 100 Year Q (cfs)
24.00 24.00
71777
20.00 20.00
16.00 16.00
12.00 12.00
8.00 8.00
4.00 4.00
0.00 0.00
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Time (min)
— Hyd No. 4 —Hyd No. Total storage used = 31,320 tuft

Hydraflow Rainfall Report
Hydraflow Hydrographs by Intelisolve v9.23
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA(
(Yrs)
B
D
. E
j (NIA)
1
51026430000
.0000117.4102
4.4955
------
2
0.0000
0.0000
0.0000
-----
3
0.0000
0.0000
0,0000
------
5
i
0.0000
0.0000
0.0000
----
10
39801970000
000009000
0,0009.7014
----
25
0.0000
0.0000
0.0000
----
50
0.0000
0.0000
0.0000
i ------
100
� 74.7444
9.3000
0.6599 --
-- - I
File name: EC Manual DMC 6-14-08.pcp.IDF
Intensity = B / (Tc + D)"E
Tuesday, Aug 26, 2008
Return
Period
(Yrs)
I 5 min
--
to-
-
15
20
Intensity
25
Values
30
(in/hr)
35
40
1 45
50
55
60
1
2.70
2.52
2.35
2.20
2.06
1.93
1.81
( 1.70
I 1.60
1.50
1.41
1.33
2
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
(
1 5
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
I 000
0.00
0.00
0.00
10
5.00
4.69
I 4.40
4.13
3.88
3.64
3.42
3.22
i 3.02
2.84
2.68
2.52 1
25
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
j 0.00
00
0L00
0.00
0.00
50
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.0000
0.00 '
0.00
100
12.92
10.60
9.11
8.05
7.25
6.63
6.13
5.71
5.365
4.79
4.56
Tc = time in minutes. Values may exceed 60,
Precin filo -e: PC Manual DMC a_11 07.,,...
Rainfall Precipitation Table (in)
store,
-
Distribution
1-yr
2-yr
3-yr
5-yr
10-yr
25-yr 1
SCS 24-hour
3.70
0.00
0,00
0.00
7.00
1 0.00
t001
SCS 6-Hr
0.00
0.00
0.00
0.00
0.00
0.00
Huff -1st
0.00
I 0.00
0.00
I
0.00
0.00
1 0.00 0.00
0.00
Huff-2nd
0.00
0.00
1 0.00
0.00
0.00
0.00 0.00
0.00
Huff-3rd
000
0.00
0.00
0.00
0.00
0,00 0.00
0.00
Huff-41h
0,00
0.00
0.00
0.00
0.00
0.00 0.00
0.00
1
Huff-Indy
0.00
0.00
0.00
2,75
4.00
5.38 6.50
8.00
Custom
0.00
0.00
0.00
0.00
0.00 1
0.00 0.00
0.00
I�_ 1_.

STORMWATER RUNOFF
Project: Benton Concrete Designer: DMC
Basin I D: (only one) Date: 8/26/2008
Given
TOTAL DRAINAGE AREA: 257000 SF = 5.900 AC.
BUA:
Gravel Roadway/Parking
134000 SF =
3.076 AC.
Buildings/Structures, etc.
6700 SF =
0.154 AC.
Washdown/Reclaim Facility
4000 SF =
0.092 AC.
Other/Contingency
4000 SF =
0.092 AC.
TOTALS
148700 SF =
3.414 AC.
DESIGN RAINFALL DEPTH: 1.5 INCHES
Calculations
BUA / DA:
0.579
"R" VALUE:
0.571
VOLUME OF RUNOFF:
18335 CF
PERMANENT POOL AVERAGE DEPTH:
4 FT
85% OR 90% TSS REMOVAL?
90
SA / TDA from TABLE
5.09%
REQUIRED MINIMUM SURFACE AREA OF
13081 SF
PERMANENT POOL
Compass Pointe Engineering, PA DMC
Ocean Isle Beach, NC 8/26108

5�%.07710
NCDENR Stormwater BMP Manual
Revised 09-28-07
"fable 10-4
Surface Area to Drainage Area Ratio for Permanent Pool Sizing to Achieve 90 Percent 1'SS
Pollutant Removal Efficiency in the Coastal Region, Ada ted from Driscoll,1986
Percent Permanent Pool Average Depth (ft)
Impervious
Cover
3.0
3.5
4.1 4-1
5.0
10 %
1.3
1.0
0.8 0.7
0.6
2001-
2.4
2.0
1.8 1.7
1.5
30%
3.5
3.0
2.7 2.5
2.2
40%
4.5
4.0
3.5 3.1
2.8
50%
60%
.56
5.0
4.3 3.9
3.5
7.0
6.0
5:35'09 4.8
4.3
70%
TO
6.0 5.5
5.0
80%
L12
8.0
7.0 6.4
5.7
90%
9.0
7.9 7.2
6.5
00 %
10.0
8.8 8.1
7.3
5.5
6.0
6.5
7.0
7.5
0.5
0.4
0.3
0.2
0.1
1.4
1.2
1.0
0.9
0.6
1.9
1.6
1.3
1.1
0.8
2.5
2.1
1.8
1.4
1.1
3.1
2.7
2.3
1.9
1.5
3.9
3.4
2.9
2.4
1.9
4.5
3.9
3.4
2.9
5.2
4.6
4.0
3.4
2.3
2.8
5.9
5.2
4.6
3.9
3.3
6.6
5.8
5.1
4.3
3.6
The engineering design of a wet detention basin trust include a 10-foot-wide (minimum)
vegetated shelf around the full perimeter of the basin. The inside edge of the shelf shall
be no deeper than 6" below the permanent pool level, and the outside edge shall be 6"
above the permanent pool level. For a 10' wide shelf, the resulting slope is 10:1. With
half the required shelf below the water (maximum depth of 6 inches), and half the
required shelf above the water, the vegetated shelf will provide a location for a diverse
population of emergent wetland vegetation that enhances biological pollutant removal,
provides a habitat for wildlife, protects the shoreline from erosion, and improves
sediment trap efficiency. A 10' wide shelf also provides a safety feature prior to the
deeper permanent pool.
Short-circuiting of the stormwater must be prevented. The most direct way of
minimizing short-circuiting is to maximize the length of the flow path between the inlet
and the outlet: basins with long and narrow shapes can maximize the length of the flow
path. Long and narrow but irregularly shaped wet detention basins may appear more
natural and therefore may have increased aesthetic value. If local site conditions prohibit
a relatively long, narrow facility, baffles may be placed in the wet detention basin to
lengthen the stormwater flow path as much as possible. Baffles must extend to the
temporary pool elevation or higher. -A minimum length -to -width ratio of 1.5:1 is
required, but a flow path of at least3:1 is recommended. Basin shape should minimize
dead storage areas, and where possible the width should expand as it approaches the
outlet.
Although larger wet detention basins typically remove more pollutants, a threshold size
seems to exist above which further improvement of water quality by sedimentation is
negligible. The water treatment volume within a wet detention basin is calculated as the
total volume beneath the permanent pool water level, and above the sediment storage
volume, including any such volume within the forebay.
Wet Detention Basin
10-10
July 2007

Project Name: Benton Concrete
Designer: DMC Date:
8/26/2008
Calculated Volume of Runoff from 1 1/2" Rainfall442.2
cf
Minimum Permanent Pool Surface Area Requiredsf
Actual Permanent Pool Surface Area Providedsf
Elevation of Permanent Poolft
MSL
Surface Area of SW Storage (Temporary) Poolsf
Elevation of SW Storage (Temporary) Poolft
MSL
Size of Odfi 2 32 in. (ID of 2 1/2" Sch
Time Increment for Routing 2 hours 80 PVC)
Area of Orifice 0.0293 sf
Depth Between Permanent Pool and SW Storage Pool 1.2 ft
Volume Between Permanent Pool and SW Storage Pool 19940 cf
Ratio of Approximate Volume to Required Volume 1.09
R O U T / N G T A B L E
Time (hours
from start of
Elevation
I Volume
Head Above
Orifice O
Volume thru
drawdown)
(ft. MSL)
Stored (cf)
Orifice (ft.)
(cfs)
0.1548
Orifice (cf)
1114_
_ 0 J
_ 42.2
� 19940
1.2
2
13
118826
1.13
_j
_0.1504
1083
4
1 42.07 _
I 17743
1.07
0.1460
f 1051
6
f _42.00 _
16692
1.00
_
0.1416
_
1020
8 I_41.94
15672
1-1
0.94
0..11310782
1988
__9
10 41.88
4684
08�
01328
72
41.83
I 3728
83
0.1284
925
14
i41.72
11911
.
0.72
07240
0.1196
893.7
861
16
4166
41.62
11050
10220
0.66
0.6220
0.1152
__
829
798
22 1
41.57
_1_
1 766
24
1 41.52
8656
0.52
0.1020
_
1 734
26 �._
4148
1 7922
_
0.48
_
0.0975
_
I_ 702
41.43
I 7220
0.43 1_
0.0931
671
30
1 41.39
6 449
0.39 '
i)i
_
�_ 639
32
_
_41.36 _
5911
0.36 j
0.0843
_
607
34 _I_
41.32
% 5304
0.32
0.0798
575
_ 36 1
41_28--;
4729
0.28 _0.0754
0.25 0.0709 -_
1 543
j 511
38 _
41.25
4187
40
41.22 _1
3676
0.22
_
478
_ _0.0665 _
0.0620 �_ _ 446
41.17 1 751 0.17 0.0575 (414
44 --1
- - 46 -
_', _
41.14 i__2337 0.14 i_ 382
48 j'-
_�-_-
_ _0.0530
41.12_� 1956 0.12 1 0.0485 -- 349 -_
1607 0.10 0,0439 1 316
_ 50
52
_ _ _ _
+I 3_
41_08 1 1291�0.08 0.94 28
03_
41.06 _ _I_ 1007 _ I_ 0.05 I _0.0348 I250
_ 41.05_ _ _ _ 757 j_ 0.05 0.0_301 1217 _
4103 440 0.03 0.0255 1 183
41.02 ! _ 356 0_.02 0.0207 �T_ 149--
_-_ .
54
56
58
60 '
__..-
62
--_64 --�
_ _,_ _ _
41.01 2070.01 0.0158 -', 114-�-
41.01 --j--- 94 -T- -0.01 0.0106 ---- 76
66
41.00 17 0.00 0.0046 33
= 2.5
Wisteria Place
Compass Pointe Engineering
DMC, 8/7/08

Benton Concrete
FOREBAY VOLUME COMPARED TO TOTAL VOLUME
DMC, 9122/08
Description
Elevation Ft
(
Surface
Main Pond
Area'
Main Pond Volume (CF)
Forebea Surface
Foreba Volume
Y
CF
( )
MSL)
(SF)
Incremental Accumulative
Area (SF)
Incremental
Accumulative
(Sediment Storage)
33.0
(n/a)
(n/a)
Bottom of Pond
- -
34.0
1,612
_ 0
--_
----- -
- -
35.0
2,491
2,052 2,052
--
36.0
3,410 i
2,951
37.0 j
4,367 �_3.889
1 8,891
1,321
1,191
1,191
38.0
5,363
4,865 7 13,756
1,612
_
1,467 j
2,657___
_
39.0
6,392
5,878 19,633
1,930
1,771
4,428
40.0
7,450
6,921 26,554
2,217
2,074 1
6,502
Bottom of Vegetative Shelf
40.5
8,093
3,886 30,440
_
_
2,496
1,178
Permanent Pool-
�_ 41.0 ;
10,678_
I�1,285
'
Top of Vegetative Shelf_
41.5 �_
13,343
4,693_ 35,133
6,005 41,138
2,644
2,862
_
1,377
8,96_5____
10,341
_
-.
Temporary Pool
i 42.2
14,490
9,742 1 50,879
3,176
2,113
12,455
FOREBAY VOLUME / TOTAL VOLUME
@ PERMANENT POOL ELEVATION =
0.20329499
Compass Pointe Engineering, PA

�r
Benton Concrete DMC 9122/08
Computation of Pond Average Depth
New formula:
D avg. _ .25 x (1+ A bot shelf/A perm pool) + (((A bot shelf + A bot pond)/2) x depth) )/ A bot shelf
Where: "A bot shelf' includes main pond and forebay
"A perm pool" includes main pond and forebay
"A bot pond' includes main pond only
DESIGN PERMANENT POOL AVERAGE DEPTH (FT.)
4
FT.
MINIMUM PERMANENT POOL SURFACE AREA REQUIRED (SF)
13081
SF
MINIMUM STORAGE REQUIRED FOR RUNOFF FROM 1 1/2"
RAINFALL:
18335
CF
Area at the permanent pool elevation
13322
SF
Elevation of permanent pool
41.0
Feet
Area at the bottom of vegetative shelf
10589
SF
Elevation of the bottom of the vegetative shelf
40.5
Feet
Area at the bottom of the pond
1612
SF
Elevation at the bottom of the pond
34.0
Feet
4.19
Compass Pointe Engineering, P.A.
Ocean Isle Beach, NC

BENTON CONCRETE SEDIMENT BASIN DATA TABLE BASED ON CONSTRUCTION PERIOD OF PROJECT
Estimated
Minimum per EC Manual
Provided
Total Drainage
Disturbed Area
Construction
110
I. D.
Area (ac.)
During
Period Rational
(in..
O 10 (cfs)
Surface Area
Volume @ 1,800
Surface Area At Top of
Volume Between Top of
Construction
(ac.)
C Value
(SF) @ 435
CF per Distrubed
Overflow Weir Elevation
Overflow Weir and
SFICFS
Acre (CF)
(SF)
Drawdown Elevation (CF)
Sw
I
BASIN 5.90
I I
5.90
0.30
1 9.70
17.2
7,469
10,620
18,428
19,943
Surface Area and Volume OK
Compass Pointe Engineering
Ocean Isle Beach, NC
DMC
8126108

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Zwes�e : a T wl
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t:J
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38`26'08,stm U8
���_---_'-----'---_�-_-_''---'-_---__�-_-_
I - nxc)

ientory Report
Page 1
t
Flow Data
Physical Data
Line ID
Junc
Known
Drng
Runoff
Inlet
Invert
Line
Invert
Line
N
J-loss
Inlet/
type
Q
area
coeff
time
El Dn
slope
El Up
7(in)
type
value
coeff
Rim El
(cfs)
(ac)
(C)
(min)
(ft)
( % )
(ft)
(n)
(K)
(ft)
DrGrt
0.00
1.40
0.60
5.0
37.50
1.25
38.00
36
Cir
0.013
1.50
44.00
SD -Al
DrGrt
0.00
0.20
0.55
5.0
40.00
1.67
41.00
18
Cir
0.013
1.05
45.50
SD-A2
DrGrt
0.00
0.20
0.65
5.0
41.00
0.73
41.80
18
Cir
0.013
1.09
46.00
SD-A3
DrGrt
0.00
0.80
0.55
5.0
41.80
0.67
42.20
15
Cir
0.013
1.00
45.20
SD-A4
DrGr1
0.00
1.70
0.65
5.0
38.00
0.45
39.30
30
Cir
0.013
1.09
43.20
SD-B1
DrGrt
0.00
0.20
0.45
5.0
39.50
1.00
40.00
18
Cir
0.013
1.47
43.20
SD-B2
DrGrt
0.00
0.80
0.50
5.0
40.00
0.63
40.50
15
Cir
0.013
1.00
43.50
SD-B3
?6-08.stm
Number of lines: 7
Date: 08-28-200
8
Hydrallow Storm Sewers 2005
V

Storm Sewer Summary Report
Page t
Line
No.
Line ID
-
Flow
rate
(cfs)
Line
size
(in)
Line
length
(k)
Invert
EL Dn
(ft)
Invert
EL Up
(ft)
Line
slope
(%)
HGL
down
(ft)
HGL
up
(ft)
Minor
loss
(ft)
HGL
Junct
(ft)
Dns
line
No.
1
SD -Al
20.01
36 c
40.0
37.50
38.00
1.250
41.90'
41.94'
0.19
42.12
End
2
SD-A2
4.75
18 c
60.0
40.00
41.00 -
1.667
42.14
42.22
0.15
42.38
1
3
SD-A3
4.13
18 c
110.0
41.00
41.80
0.727
42.44
42.59
0.32
42.91
2
4
SD-A4
3.25
15 c
60.0
41.80
42.20
0.667
43.10
43.22
0.14
43.36
3
5
SD-BI
11.24
30 c
290.0
38.00
39.30
0.448
42.17'
42.38'
0.09
42.47
1
6
SD-B2
3.52
18 c
50.0
39.50
40.00
1.000
42.49'
42.55'
0.09
42.64
5
7
SD-B3
2.95
15 c
80.0
40.00
40.50
0.625
42.64'
42.81'
0.09
42.90
6

Storm Sewer Summary Report
7Tr -5
Page 1
Line
Line ID
Flow
Line
Line
Invert
Invert
Line
HGL
HGL
Minor
HGL
Dns
No.
rate
size
length
EL On
EL Up
slope
down
up
loss
Junct
Tine
(cfs)
(in)
(ft)
(ft)
(ft)
M
(ft)
(ft)
(ft)
(ft)
No.
1
-
SD -Al
27.30
36 c
40.0
37.50
38.00
I
1.250
42.46'
42.53'
0.35
42.87
End
2
SD-A2
6.33
18 c
60.0
40.00
41.00
1.667
42.91'
43.13'
0.21
43.33
1
3
SD-A3
5.45
18 c
110.0
41.00
41.80
0.727
43.39'
43.68'
0.16
43.84
2
4
SD-A4
4.26
15 c
60.0
41.80
42.20
0.667
43.84'
44.11'
0.19
44.29
3
5
SD-B1
14.95
30 c
290.0
38.00
39.30
0,448
42.96'
43.35'
0.16
43.50
1
6
SD-B2
4.66
18 c
50.0.
39.50
40.00
1.000
43.54'
43.64'
0.16
43.80
5
7
SD-83
3.88
15 c
80.0
40.00
40.50
0.625
43.80'
44.09'
0.16
44.24
6
I
L� -
eeLr
I
i
i
i
i

Line Computations
Page 1
Downstream
Len
Upstream
Check
JL
Mlnor
(ft)
coeff
(K)
loss
(ft)
_
r
Depth
(ft)
Area
(sgft)
Vel
(fVs)
Vel
head
(ft)
EGL
elev
(ft)
Sf
N
Invert
elev
(ft)
HGL
elev
(ft)
Depth
(ft)
Area
(sgft)
Val
(ft/s)
Vel
head
(ft)
EGL
elev
(ft)
Sf
(°/)
Ave
Sf
M)
Enrgy
loss
(ft)
3.00
7.07
2.83
0.12
42.02
0.090
40.0
38.00
41.94
3.00
7.07
2.83
0.12
42.06
0.090
0.090
0.036
1.50
0.19
1.50
1.77
2.69
0.11
42.25
0.205
60.0
41.00
42.22
1.22
1.54
3.08
0.15
42.37
0.206
0.205
0.123
1.05
0.15
1.44
1.74
2.37
0.09
42.53
0.135
110
41.80
42.59
0.79
0.94
4.37
0.30
42.89
0.518
0.327
0.359
1.09
0.32
1.25
1.23
2.65
0.11
43.21
0.253
60.0
42.20
43.22
1.02
1.07
3.02
0.14
43.36
0.254
0.254
0.152
1.00
0.14
2.50
4.91
2.29
0.08
42.25
0.075
290
39.30
42.38
2.50
4.91
2.29
0.08
42.47
0.075
0.075
0.218
1.09
0.09
1.50
1.77
1.99
0.06
42.55
0.113
50.0
40.00
42.55
1.50
1.77
1.99
0.06
42.61
0.112
0.112
0.056
1.47
0.09
1.25
1.23
2.41
0.09
42.73
0.209
80.0
40.50
42.81
1.25
1.23
2.41
0.09
42.90
0.209
0.209
0.167
1.00
0.09
t
1 q
I
.08.stm
Number of lines: 7
Run Date: 08-28-2008
Hytlraflmv Storm Sewers 2 OS
n

Line Computations
Page 1
Downstream
Len
Upstream
Check
JL
Minor
coeff
loss
L
Depth
Area
Vol
Vel
EGL
Sf
Invert
HGL
Depth
Area
Val
Val
EGL
Sf
Ave
Enrgy
head
elev
elev
elev
head
elev
Sf
loss
(ft)
(sgft)
(f 1s)
(ft)
(ft)
N
(ft)
(ft)
(ft)
(ft)
(sgft)
(ft/s)
(ft)
(ft)
M
M
(ft)
(K)
(ft)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
I
3.00
7.07
3.86
0.23
42.69
0.168
40.0
38.00
42.53
3.00
7.07
3.86
0.23
42.76
0.168
0.168
0.067
1.50
0.35
1.50
1.77
3.58
0.20
43.11
0.364
60.0
41.00
43.13
1.50
1.77
3.58
0.20
43.32
0.364
0.364
0.218
1.05
0.21
t
1.50
1.77
3.08
0.15
43.53
0.269
110
41.80
43.68
1.50
1.77
3.08
0.15
43.83
0.269
0.269
0.296
1.09
0.16
1.25
1.23
3.47
0.19
44.03
0.436
60.0
42.20
44.11
1.25
1.23
3.47
0.19
44.29
0.436
0.436
0.262
1.00
0.19
2.50
4.91
3.05
0.14
43.11
0.133
290
39.30
43.35
2.50
4.91
3.04
0.14
43.49
0.133
0.133
0.385
1.09
0.16
1.50
1.77
2.64
0.11
43.65
0.197
50.0
40.00
43.64
1.50
1.77
2.64
0.11
43.75
0.197
0.197
0.098
1.47
0.16
1.25
1.23
3.16
0.16
43.95
0.360
80.0
40.50
44.09
1.25
1.23
3.16
0.16
44.24
0.360
0.360
0.288
1.00
0.16
V
-08.stm
Number of lines: 7
Run Date: 08-28-2008
Hydrellow Storm Sewers 2005
J
u

Wile
Proj. file: Benton Basins A & B 8-26-08.stm
7 r A g Al ) A
a
50 75 100 125 150 175 200 225 250 275
Reach (ft)
Hydraflow Storm Sewers

Wile
Proj. file: Benton Basins A & B 8-26-08.stm
2 - YE,+P- A 1 E-3
r44E5034.001
7.9):188.00
r. El. 38:00
iOut
In
Sta
3+30'00 8 9680,00 - L �6 Sta 4+6a
-
I Rin
Inv.
Inv:
El-43.
E1:-39.
EL 39:
Vi
Oro
OduE1:
-El; 43:20
EI, 40:00 O
40:00 In�
t
Rim El. q
Inv:'EI. 4
I
i
I
I
_
I
�
i
r
I I
90.01-f - 30" @ 0.45%
�15@ 1
J
4 i
100 150 200 250 300
Reach (ft)
.00 - Ln: 7
3.50
D.50 Out
350 400 450 500
Hydraflow Storm Sewers

,ofile
Proj. file: Benton Basins A & B 8-26-08.stm
44.51IRim.El. 44.001 Rim EI. 4�.-0500-Out
7.50 IYmvi. El. 38.00 Out Inv.EL4
Inv, El. 40.00 In Inv. El. 400In
, a
i i I
I
60.0U- 18" Q 1.67%
I I
,
50
75
100
Al > A
110.01-f 18" Q 0.
I i
I
125 150
Reach (ft)
Rim -El. 46.00-
Inv._�I. 41.80 O
Inv. El. 41.80 In
15'
I
175 200 225 250
la 2+70.00 - L_n: 4
inn El. 45.20
v. El. 42,20 Out
275
Hydraf ow Storm Sewers

Wile
Proj. file: Benton Basins A & B 8-26-08.stm
1E,?
100 150 200 250 300 350 400 450
Reach (ft)
i0.00 - L_n: 7
43.50
40.50 Out
500
Hydraflow Storm Sewers

iew
No. Lines: 2 08-29-2008
Hydrallow Storm Savers 2005
lv

rentory Report
Page 1
it
Flow Data
Physical Data
Line ID
June
Known
Drng
Runoff
Inlet
Invert
Line
Invert
Line
Line
N
J-loss
Inlet/
type
Q
area
coeff
time
El Dn
slope
El Up
size
type
value
coeff
Rim El
(cfs)
(ac)
(C)
(min)
(ft)
(°/,)
A
(in)
(n)
(K)
(ft)
MH
0.00
0.00
0.00
0.0
46.60
0.29
46.80
12
Cir
0.013
0.99
49.60
SD-A5
DrGrt
0.00
0.20
0.50
5.0
46.80
0.50
47.00
12
Cir
0.013
1.00
48.80
SD-A6
'
Number of lines: 2
Date: 08-29-200
8
Hydfafi" Sloop Saeara 2 05
W

Storm Sewer Summary Report
Page 1 �TEI—
l4-
Line
No.
Line ID
Flow
rate
(cfs)
Line
size
(in)
Line
length
(ft)
Invert
EL Dn
(ft)
Invert
EL Up
(ft)
Line
slope
M
HGL
down
(ft)
HGL
up
(ft)
Minor
loss
(ft)
HGL
Junct
(ft)
Dns
line
No�
1
SD-A5
0.95
12 c
70.0
46.60
46.80
0.286
47.01
47.36
0.07
47.42
End
2
SD-A6
0.97
12 c
40.0
46.80
47.00
0.500
47.47
47.50
0.09
4L60
1

Line Computations
Page 1
Downstream
Len
Upstream
Check
JL
Minor
coeff
loss
iL
Depth
Area
Vol
Vol
EGL
Sf
Invert
HGL
Depth
Area
Vol
Vol
EGL
Sf
Ave
Enrgy
v
head
elev
elev
elev
head
elev
Sf
loss
t
(ft)
(soft)
(fUs)
(ft)
(ft)
N
(ft)
(ft)
(ft)
(ft)
(s9ft)
(ftls)
(ft)
(ft)
(%)
(%)
(ft)
(K)
(ft)
1
0.41
0.31
3.09
0.15
47.16
0.555
70.0
46.80
47.36
0.56
0.45
2.10
0.07
47.43
0.197
0.376
0.263
0.99
0.07
7
0.67
0.56
1.73
0.05
47.52
0.119
40.0
47.00
47.50
0.50
0.40
2.44
0.09
47.60
0.287
0.203
0.081
t
1.00
0.09
Number of lines: 2
Run Date: 08-29-2008
Hydratlow Storm Sewers 2

Wile
Proj. file: Benton A5 to A6 8-26-08.stm
2-YEli (2 •4 -) If-6,
.00 -- Outfall�I—�
0 0.00 - Ln: 1
Sta_1_+__
5T60
b
Rim El: 4 .60
Rim EI.
8.60 In
Inv. El. 46 80 Out
Inv. El.
Inv. El. 46 80 In
—r ---
I
I
I
I
�
I
I
i
I
20 30 40 50 60 70 80 90 100 110
Reach (ft)
10_00_-_Ln:_2
48.80
47.00 Out
Hydraflow Storm Sewers 2005

,ofile
Proj. file: Benton A5 to A6 8-26-08.stm
l6-Ycltfe *C
.00 - Outfall
Sta 0+.70.
0, _Ln:_1.
Sta 1+10.00 - Ln: 2
51.60
Rim fl. 4
.60
Rim E1. 48.80
5.60 1n I
Inv. El: 4.180
Out-
Inv. r L 47.00 Out
Inv. El. 46180
In
20 30 40 50 60 70 80 90 100 110
Reach (ft)
Hydraflow Storm Sewers

N
14YnIzaLoc-Y
D, A.
611 a.
Val
AIA
o.�.
0.6S
5
29
A2A
013
0.66
al p
p, s
os5
R /
0.4
P 2 A
0.8
d.5o
928
0.2
0.I�5
WIDRAULICS
?D
SLOPE (%,)
AIA
o.9/
A- IF
. ?3
32A
�01
V .53
C2A
0.9 I
2- si

ALES DATA TABLE - ESTABLISHED GRASSED -LINED CHANNELS DMC 0/28/2008
Swale Average
Velocity
Slope In Most
D w Will
Type Channel Liner
Description of Channel to Use
Allowed from
Manning's "n"
Velocity
Flow Depth
Critical Area
from Table 8.05a
Table 8.05a
Value
Actual (fps)
Oft)
(Ft/Ft)
(fps)
0.0091 -- 5.0
grass
0-5% slope; easily erodible;
Bermudagrass
5.0
0.068
1.4 1.1
j0.0030 2.9
grass
0-5% slope; easily erodible;
Bermudagrass
5.0
0.091
0.7 1.2
0,0053 1 1.7
I grass
i 0-5% slope; easily erodible;
5.0
Ir 0.130
0.5 1.1
i
Bermudagrass
1 0-5% slope; easily erodible
i
0.0145 2.7
grass
1
I Bermudagrass
5.0
0.081 I
1.2 0.9
0.0091 11
grass
0-5% slope; easily erodible;
5.0
0.055
1.9 1.4
I
Bermudagrass
0.0091
3.9
grass
9
0-5% slope; easily erodible;
Bermudagrass
5.0
0.076 1.2 1.1
-----r------
0.0333
1.3
-----I
grass
---
0-5% slope; easily erodible;
Bermudagrass
-
I
5.0
-`-----i- ..
i
0.097 1.2 0.6
I
1. Channels are "V-shaped" with 3:1 side slopes
2. Manning's "n"value based on trial 8 error procedure balancing HydroFlow computations with Fig. 8.05c of EC Manual using retardance class V'.
3. Time of concentration based on Kirpich equation with minimum value of 5 minutes.
4. Intensity taken from EC Manual, it, 8.03.9 for Wilmington.
Seed and fertilizer shall be applied immediately after construction of all ditches. Further, swales A1A, A2B, B1, B2A, AND B2B shall be protected by placement
of a protective liner immediately after seeding and fertilizer application. (See'Temporary Swale Channel Liner Calculations".) Check dams will be placed at
intervals along the ditch line as shown on the project plans.
Compass Pointe Engineering
Ocean Isle Beach, NC

M
02
Appendices
Step 10. For grass -lined channels once the appropriate channel dimensions
have been selected for low retardance conditions, repeat steps 6 through 8 using
a higher retardance class, corresponding to tall grass. Adjust capacity of the
channel by varying depth where site conditions permit.
NOTE 1: If design velocity is greater than 2.0 ft/sec., a temporary lining
may be required to stabilize the channel until vegetation is established.
The temporary liner may be designed for peak flow from the 2-yr storm.
If a channel requires temporary lining, the designer should analyze shear
stresses in the channel to select the liner that provides protection and
promotes establishment of vegetation. For the design of temporary liners,
use tractive force procedure.
NOTE 2: Design Tables —Vegetated Channels and Diversions at the end
of this section may be used to design grass -lined channels with parabolic
cross -sections.
Step 11. Check outlet for carrying capacity and stability. If discharge velocities
exceed allowable velocities for the receiving stream, an outlet protection struc-
ture will be required (Table 8.05d, pg. 8.05.9).
Sample Problem 8.05a illustrates the design of a grass -lined channeL
nnn■n�■■EN
=n
MEE■■IIMW
mmnnn
ME
� '
....� ,Less than 2"
n
NORnnv��1111►.�n
nVv��ln►�\mn��ni�
nnnn.-,ve�n�a��■■���•
nnnn■�■IN�i��Giii■

���
BENTON CONCRETE
- TEMPORARY SWALE CHANNEL LINER CALCULATIONS (before
permanent vegetation established)
NOTES: 1. Analysis
based on 2-year peak Q.
DMC
8/29/2008
2. Channel
side slopes =
3:1 or flatter.
BARE EARTH ......
N = .02 &
PERMISSIBLE VELOCITY = 2.0 FPS
CHANNEL I.D.
Q2 (CFS)
CHANNEL
SLOPE
BARE EARTH
^M
FLOW
DEPTH
FLOW
WETTED
PERIMETER
HYDRAULIC
VELOCfTY (FPS)
LINER
(FTi;
VALUE
(FT.)
AREA (SF)
(FT.)
RADIUS (FT.)
REQUIRED?
A1A
3.8
--
I 0.0091
i 0.02
0.640
1.23
I 4.05
0.304
1 3.1
I YES
Al B
I 2.2
1 0.0038
j 0.02
0.610
0.470
1.12
( 0.66
3.86
2.97
0.290 - 1
0.222
0216 !
-2.0
2.0
3.2
I NO
- A2A-
1.3 0.0053 0.02
I 2.0 1 0.0145 0.02
NO
A2B
0.460
0.63
I 2.91
YES
0.850
2.17
1 5.38
0.403
2.2
Bi
8.2 0.0091 0.02
YES
YES
62A
3.0
10
- 0.0091
0.0333
1 0.02
0.02
0.580
1.01
0.29
3.67
I 1.96
0.275 1
0.148 1
3.0
3.5
B26
0.310
YES
CHANNEL LINER CALCULATIONS
CHANNELI.D.
Q2(CFS)
CHANNEL
SLOPE
TYPE LINER
"N"VALUE
FLOW
DEPTH
VELOCITY
SHEAR STRESS
COMPUTED
SHEAR STRESS
TYPE LINER
(FT/FT)
PROPOSED
(Fr)
(FPS)
ALLOWED(LB/SF)
(LB/SF)
ADEQUATE?
AtA 3.8 I
�
0.0091
i Jute Net
0.022
I
0.66 I
2.9
0.45
0.37 I
YES
�
I
A2B 2.0
0.0145
Jute Net
0.022 I
0.48
2.9
0.45 I
0.43
YES
YES
131 8.2 0.0091 Fiberglass
0.021 i 0.86
2.2
0.60 0.49
Roving
4
2.9
YES
_-B2A 3.0 0.0091 Jute Net
0.022 i 0.59 I
0.45 0.34
--- I - - I
Double
I---
--- - --
- ----------

Benton Ready -Mix of Brunswick, Inc. - Request for Express SW and ...
Subject: Benton Ready -Mix of Brunswick, Inc. - Request for Express SW and EC Review
From: "Don Covil" <[e-mail]>
Date: "Chu, 18 Sep 2008 15:08:47 -0400
To: "Janet Russell° <[e-mail]>
CC: "Keith Benton" <[e-mail]>, "michael Norton" <[e-mail]>
Janet,
Attached are the following pdf documents for requesting express SW and EC reviews for the subject
project:
1. Request for Express Permit Review
2. Stormwater narrative
3. Erosion Control narrative
4. Plans Cover Sheet illustrating vicinity map
5. Site Plan
We would appreciate a review date and time as follows:
• 9/30/08 2:00 p.m. or later
• 9/29/08 11:30 a.m. or later
Thanks,
Don
Donald M. Covil, P.E.
Compass Pointe Engineering, PA
6934-6 Beach Drive, SW
Ocean Isle Beach, NC 28469
[phone]
Donald M. Covil <dcovil.cpepatmc.net> 1
Compass Pointe I?ngineering, PA
EC Plan Narrative 9-2-08.doc Content -Type: application/msword
Content -Encoding: base64
-
[REQUEST EXPRESS Review 9-18-08.doc
Content -Type: application/msword
Content -Encoding: base64
Content -Type: application/msword
SW Plan Narrative 9-2-08.doc
Content -Encoding: base64
I of 2 9/18/2008 5:30 PM

S� F o �69377
North Carolina Department of Environment and
AfA Natural Resources
NCDENR Request for Express Permit Review
For DENR Use ONLY
Reviewer: C
Submit: ak0 `6
Time:
Confirm:
FILL-IN all the information below and CHECK the Permit(s) you are requesting for express review. FAX or Email the completed form to Express
Coordinator along with a completed DETAILED narrative, site plan (PDF file) and vicinity map (same items expected in the application package
of the project location. Please include this form in the application package.
0
• Asheville Region -Alison Davidson 828.296.4698;alison.davidson(o)ncmail.net
• Fayetteville or Raleigh Region -David Lee 919-791.4203; david.lee(a.ncmail.net
• Mooresville & -Patrick Grogan 704-663.3772 or patricicgrogan(�ncmail.net
• Washington Region -Lyn Hardison 252-946-9215 or Ivn.hardison(a)ncmail.net C 1 V E
• Wilmington Region -Janet Russell 910.350.2004 or tanet.russellna ncmail.net )
NOTE: Project application received after 12 noon will be stamped in the following work day. SEP 1 8 - i• /
Project Name: BENTON READY -MIX OF BRUNSWICK , County: BRUNSWICK DWQ
Applicant: KEITH A. BENTON, SR. Company: BENTON READY -MIX OF BRUNSWICK, INC. PROJ a
Address: POST OFFICE BOX 797City: CONWAY, State: SC Zip: 29528-
Phone: [phone] Fax::[phone] Email: [e-mail]
Physical Location:197 BARNHILL ROAD
Project Drains into TRIBUTARY TO WILLIAMS BRANCH waters — Water classification C:SW:HQW (for classification see-
hftp://h2o.enr.state.nc.us/bims/reports/reportsWB.html
Project Located in LUMBER River Basin. Is project draining to class ORW waters? N , within % mile and draining to class SA waters N or
within 1 mile and draining to class HQW waters? Y
Engineer/Consultant: DONALD M. COVIL, P.E. Company: COMPASS POINTE ENGINEERING, P.A.
Address: 6934-6 BEACH DRIVE, SW City: OCEAN ISLE BEACH, State: NC Zip: 28469
Phone: [phone] Fax::[phone] Email: dcovil.c [e-mail]
(Check all that
❑ Scoping Meeting ONLY ❑ DWQ, ❑ DCM, ❑ DLR, ❑ OTHER: _
❑ Stream Origin Determination: _ # of stream calls — Please attach TOPO map marking the areas in questions
® State Stormwater ❑ General ❑ SFR, ❑Bkhd & Bt Rmp, ❑ Clear & Grub, ❑ Utility
❑ Low Density ❑ Low Density -Curb & Gutter _ # Curb Outlet Swales [IOff-site[SW _ (Provide permit #)]
® High Density -Detention Pond 1 # Treatment Systems ❑ High Density -Infiltration _ #Treatment Systems
❑ High Density -Bio-Retention _ # Treatment Systems ❑ High Density—Stormwater Wetlands _ # Treatment Systems
❑ High Density -Other _ # Treatment Systems /❑ MODIFICATION: ❑ Major ❑ Minor ❑ Revision SW _
❑ Coastal Management ❑ Excavation & Fill ❑ Bridges & Culverts ❑ Structures Information
❑ Upland Development ❑ Marina Development ❑ Urban Waterfront
® Land Quality ® Erosion and Sedimentation Control Plan with 8 acres to be dislurbed.(CK # (for DENR use))
WETLANDS QUESTIONS MUST BE ADDRESSED BELOW
® Wetlands (401): Check all that apply
Wetlands on Site ® Yes ❑ No
Wetlands Delineation has been completed: ® Yes ❑ No
US ACOE Approval of Delineation completed: ® Yes ❑ No
404 Application in Process w/ US ACOE: ❑ Yes ❑ No
Permit Received from US ACOE ❑ Yes ❑ No
Fee Snlit for multiple nermita, (Check k
Isolated wetland on Property ❑ Yes N No
Buffer Impacts: ® No ❑ YES: _acre(s)
Minor Variance : ® No ❑ YES
Major General Variance ® No ❑ YES
401 Application required: ❑Yes ❑ No If YES, ❑ Regular
Perennial, Blue line stream, etc on site ❑ yes ® No
For DGNR use only
Total Fee Amount 8
SUBMITTAL DATES
Fee
I
SUBMITTAL DATES
Fee
CAMA
$
1 Variance Ma'; El Min
$
SW ❑ HD, ❑ LID, ❑ Gen
$
401:
$
LQS
$
1 Stream Deter,_
$
NCDENR EXPRESS July 2008 Gp?�, e—d to 'Q,,O nG A O r 1 _ Z,/

BENTON READY -MIX OF BRUNSWICK EROSION CONTROL PLAN NARRATIVE
Project Description
Mr. Keith A. Benton, Sr., owner, plans to build this project under the name of Benton Ready -
Mix of Brunswick, Inc. The site is just northeast of the Town of Shallotte approximately 1/3
miles north of US 17. The address is 119 Barnhill Road, NW. The project site consists of
8.55 acres of which 0.36 acres are wetlands. No wetlands are proposed for disturbance
during the construction of this project.
Approximately 39.9% of the site will be covered by "built -upon area" (BUA). The
large portion of the BUA will be gravel for the movement and parking of concrete mixer
trucks. A smaller portion of the BUA will consist of an office/maintenance building,
control house, well tank house, plant hopper/loading/conveyor system, a mixer fueling
area, a helicopter pad, and miscellaneous concrete surfaces associated with the mixer
washdown and concrete reclaim area. Stormwater runoff from all of the BUA will be
collected and directed to a wet detention pond for treatment with the exception of a
small portion of the entrance drive and the helicopter pad (30' x 30'). The helicopter pad
will be surrounded by grass surfaces graded to provide overland flow. Stormwater
collection will be by yard inlets, catch basin, storm drainage piping, and vegetated
swales.
Site Description
The project area is currently wooded except for a mobile home site (unoccupied) in the
northeast corner of the site. The mobile home will be removed from the site prior to the
completion of construction.
The project drains to a tributary of Williams Branch. Williams Branch is classified as C; Sw;
HQW. Relief ranges from a maximum elevation of approximately 53' at the northeast corner
of the site and to a minimum elevation of approximately 42' at the southeast corner of the
site. The primary soil types based on the Brunswick County Soil Survey are Baymeade and
Goldsboro.
Adjacent Property
Woodlands surround the project to the north, east, and west. The tract to the south of the
project is cleared and is currently being developed by Southport Concrete Company. .
Planned Erosion and Sedimentation Control Practices
The stormwater wet detention pond will serve as primary erosion control feature during and
construction of this project. This pond will serve as a sediment basin. Following
construction and the stabilization of all disturbed surfaces, the pond will be cleaned of
collected sediment.
Other erosion control features will include sediment fencing, a gravel construction
entrance/exit, inlet protection at yard inlets and catch basin, and temporary check dams
within grassed -lined vegetative swales. All disturbed areas shall be stabilized by vegetative
ground cover within 21 days following any completion of grading unless the final gravel
surface can be placed by that time. Within 21 days following completion of construction,
permanent ground cover over all disturbed areas not covered by BUA shall be established.
E
C
E 1
V ED
Pointe Engineering,, PA 1
September 18, 2008
RCompass
SEP
18
608
DWO
PROJ # -

BENTON READY -MIX OF BRUNSWICK STORMWATER NARRATIVE
The proposed Benton Ready -Mix of Brunswick, Inc. facility will be located within
the planning jurisdiction of the Brunswick County on tax parcel number 18200092. The
site is just northeast of the Town of Shallotte approximately 113 miles north of US 17.
The address is 119 Barnhill Road, NW. The tract area is 8.55 acres, approximately
0.36 acres of which are wetlands. No wetlands are proposed to be disturbed during the
construction of this project.
Approximately 39.9% of the site will be covered by "built -upon area" (BUA). The
large portion of the BUA will be gravel for the movement and parking of concrete mixer
trucks. A smaller portion of the BUA will consist of an office/maintenance building,
control house, well tank house, plant hopper/loading/conveyor system, a mixer fueling
area, a helicopter pad, and miscellaneous concrete surfaces associated with the mixer
washdown and concrete reclaim area. Stormwater runoff from all of the BUA will be
collected and directed to a wet detention pond for treatment with the exception of a
small portion of the entrance drive and the helicopter pad (30' x 30'). The helicopter
pad will be surrounded by grass surfaces graded to provide overland flow. Stormwater
collection will be by yard inlets, catch basin, storm drainage piping, and vegetated
swales.
The stormwater pond is designed to treat the runoff from the first 1 '/2' of rainfall
and to remove 90% of suspended solids in accordance with State regulations. The
orifice in the pond outlet structure is sized to draw down the "treatment volume" in
approximately 2 '/z days.
In addition to the State stormwater permit, application shall also be made for an
NPDES Discharge Permit for Ready -Mix Concrete Sites. Process wastewater will result
from washdown of the surface of the mixer trucks before they leave the site to deliver
concrete and from the dumping of excess concrete from mixer trucks when they return
from deliveries. A reclaim/settling facility will be used to treat the process wastewater.
A large portion of the water used in this operation will be recycled; however, there will
be some overflow into a vegetated swale that is part of the stormwater collection system
that directs runoff to the wet detention pond. The overflow is at the end of the settling
basin where a large % of the solids have been settled out. The settling facility will be
f�E C E I V E
Compass Pointe Engineering, P.A. �u,�(u D
1
September 18, 2008 SEP 18208
DWO

routinely cleaned out by front-end loaders which access the compartments of the
settling basin by ramps.
Further, application will be made to the NC Division of Air Quality for the required
air quality permit for this project.
This project drains to a tributary of Williams Branch within the Lumber River
Basin. Williams Branch is classified as C; Sw, HQW and has the stream index # 15-25-
2-9-3.
Compass Pointe I,ngineering, P.A. 2
September 18, 2008

SITE, STORMWATER,
AND EROSION CONTROL PLANS
FOR
BENTON READY -MIX
OF BRUNSWICK, INC.
LOCKWOOD FOLLY TOWNSHIP
UTILITY COMPANIES COUNTY Of BRUN5WICK
BRUN5wCK ELECTRIC (ELECTRIC (910) 754<391 NORTH CAKOUNA
ATLANTIC TELEPHONE (TELEPHONE i CABLE) (91 O) 754-4311 (ON SITE WATER • SEWER) 5EP T EMBER 2005
CS PROJECT COVER SHEET
CMETI
NG STING CONDRION5
C2 SITE PUN
C3 5TORMWATER AND GRADING PUN
C4 ERO5ION CONTROL PUN
C5 STORMWATER POND DETAILS
CG ER05ION CONTROL 15TORMWATER NOTES AND DETAILS
C7 MISCELLANEOUS DETAILS
HI HERITAGE TREE SURVEY
LI LANDSCAPE PLAN
SIT
VIC.'ININ MAP
NOT TO SCALE
M1, -. ANn 7cVFi"I
BENTON F AUY-MIX Of 9RUNSlNCK INC.
P.O. BOx 797
CONWAY. 5C 2952E
�TOwfNNS
LAND
SUP.VEItNG
P.P.
FOUNTAIN HEAD LANDING
C934 SUITE G BEACH DRIVE 5W
OCEAN ISLE BEACH. NORTH CAROLINA 2F4G9
PHONE [phone]
'•Pfa."°I, s'ia,`,W,S:�` FINAL DRAWING.
:,rOs,�=-•4:O`f- NOT SS 1Fn FOR
•O'n�nnra ••.,,,,��..�.•• f0'JSTRi IfT ON

O
OpU
Op
1 E C E' V E D
DWO
.nTQ ME
MATC LINE
�amiwu wvev ns �nao

State of North Carolina
Department of the Secretary of State
APPLICATION FOR CERTIFICATE OF AUTHORITY
Date Filed: 9/15/2008 10:06:00 AM
Elaine F. Marshall
North Carolina Secretary of State
C200825600284
Pursuant to §55-15-03 of the General Statutes of North Carolina, the undersigned corporation hereby applies for a Certificate of
Authority to transact business in the State of North Carolina, and for that purpose submits the following:
1. The name of the corporation is Benton Ready -Mix of Brunswick. Inc. ; and if the corporate name is
unavailable for use in the State of North Carolina, the name the corporation wishes to use is:
2. The state or country under whose laws the corporation was organized is: South Carolina
3. The date of incorporation was May 1, 2008 ; its period of duration is: perpetual
4. Principal office information: (Select either a or b)
a. ❑/ The corporation has a principal office.
The street address and county of the principal office of the corporation is:
Number and Street 309 Highway 544
City, State, Zip Code Conway SC 29526 County Marry
The mailing address, tf different from the sheet address, of the principal office of the corporation is:
Same as above.
b. ❑ The corporation does not have a principal office.
5. The street address and county of the registered office in the State of North Carolina is:
Number and Street 197 Barnhill Road NW
City, State, Zip Code Shallotte, NC 28470 County Brunswick
6. The mailing address, if dfferent from the street address, of the registered office in the State of North Carolina is:
Same as above.
7. The name of the registered agent in the State of North Carolina is: Keith A. Benton, Sr.
8. The names, titles, and usual business addresses of the current officers of the corporation are (attach if necessary):
Name �tle Business Address
Keith A. Bentorf; Sr. C-President 309 Hwy. 544, Conway, SC 29526
9. Attached is a Certificate of Existence (or document of similar import) duly authenticated by the Secretary of State or other
official having custody of corporate records in the state or country of incorporation. The Cert%TCate of Existence must be
an orieinal and less than six months old.
CORPORATIONS DIVISION P. O. BOX 29622 RALEIGH, NC 27626-0622
(Revised January, 2002) (Form B-09)

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APPLICATION FOR CERTIFICATE OF AUTHORITY
Page 2
10. If the corporation is required to use a fictitious name in order to transact business in this State, a copy of the resolution of its
board of directors, certified by its secretary, adopting the fictitious name is attached.
11. This application will be effective upon filing, unless a delayed date and/or time is specified: NIA.
This is the 10'�&y of !�jef • 2008
Bentorrfp6ady-Mix of Brunswick, Inc
Name of rporatio (
Signature
Kei h A. Benton, Sr., President
Type or Print Name and Title
NOTES:
1. Filing fee is $250. This document must be filed with the Secretary of State.
CORPORATIONS DIVISION P. O. BOX 29622 RALEIGH, NC 27626-0622
(Revised January, 2002) (Form B-09)

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The State of South Carolina
Office of Secretary of State Mark Hammond
Certificate of Existence
1, Mark Hammond, Secretary of State of South Carolina Hereby certify that:
BENTON READY -MIX OF BRUNSWICK, INC.,
a corporation duly organized under the laws of the State of South Carolina on
May 1st, 2008, and having a perpetual duration unless otherwise indicated
below, has as of the date hereof filed all reports due this office, paid all fees,
taxes and penalties owed to the Secretary of State, that the Secretary of State
has not mailed notice to the Corporation that it is subject to being dissolved by
administrative action pursuant to section 33-14-210 of the South Carolina Code,
and that the corporation has not filed articles of dissolution as of the date hereof.
Given under my Hand and the Great
Seal of the State of South Carolina this
6th day of May, 2008.
WEE le'=11"
Mark Hammond, Secretary of State

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