SW8090217_Historical File_20120112

MIRACLE FIELD
STORMWATER & EROSION CONTROL
NARRATIVE & CALCULATIONS
December 8, 2011
DDEC, 0 2011
BY:
GSP Consulting, PLLC.
6626 Gordon Road, Unit C
Wilmington, North Carolina 28411
[phone]

STORMWATER NARRATIVE
OLSEN PARK- MIRACLE FIELD
NEW HANU" iVER COUNTY, NC
SITE DESCRIPTION
This +/- 89.4 acre site is located off Olsen Park Drive in New Hanover County, North Carolina.
The site drains to existing ditches and streams surrounding the property: This phase of the
project will consist of the construction of a recreation field and related site appurtenances. The
proposed drainage area for this project includes 3.31 acres draining to a proposed grassed
swale/dry detention system with 2.66 acres of undetained runoff.
SOILS
The soils for this project consist of Seagate series soils (Hydrologic Soil Group A). The Seagate
Series soils consist of somewhat poorly drained, moderately permeable soils that formed in
marine sediment.
STORM DRAINAGE DESIGN
The primary stormwater measure for this project is a grassed swale/dry detention system. The
stormwater will be conveyed via overland sheet flow to the stormwater system.
Existing Built -Upon Area
221,793 s.f.
Proposed. Built -Upon Area
86,017 s.f.
New Built -Upon Area
307,810 s.f.
Permitted Built -Upon Area
934,351 s.f.
Future Available Built -Upon Area
626,541 s.f.

EROSION CONTROL PLAN FOR
MIRACLE FIELD
This +/- 4.04 acre site is located within Olsen Park and is part of a larger low -density
community park project. The site drains to a ditch that runs along the property boundary
before ultimately reaching Smith Creek located approximately 0.50 mile away. There are
2 proposed drainage areas for this project that will drain to the proposed dry detention
basin/grassed swale. The basin/swales are design to collect stormwater sheet flow runoff
from both sides of the field and collect in the middle to an outlet structure and discharge
into the existing ditch. Basin/Swale #1 drainage area is 1.25 acres and the total amount of
impervious area draining to the wet detention basin is 62.6%. Basin/Swale #2 drainage
area is 2.07 acres and the total amount of impervious area draining to the wet detention
basin is 42.1%. The proposed disturbed area for this project is approximately 4.04 acres,
of which approximately 1.79 acres has been previously permitted. The primary
stormwater measures for this project will be a dry detention basin/grassed swale. The
stormwater will be conveyed via overland sheet flow to the proposed dry detention
basin/grassed swales that are designed to control the post development peak discharge for
the 2, 10 & 25-year storm events so as not to exceed the pre -development peak runoff
discharge rate to meet New Hanover County Regulations. The site drains to a ditch that
runs along the property boundary before ultimately reaching Smith Creek (Classification
C, Sw) located approximately 0.50 mile away.
EROSION CONTROL MEASURES: This project will primarily control erosion with the
use of a temporary construction entrance, inlet protection and silt fence surrounding the
site.
The contractor shall install, maintain and remove upon completion the silt fence as
necessary to prevent any sediment from leaving the project limits. This will include any
temporary stockpile areas if necessary. Contractor shall clean and restore to pre -
construction conditions any areas that may inadvertently be damaged due to the failure of
the erosion control measures.
SCHEDULING OF WORK: Clearing and grubbing shall be scheduled and performed in
such a manner that fine grading operations and erosion control practices can follow
immediately thereafter. Excavation and embankment operations will be conducted such
that cuts and fills will be completed to final grades in a continuous operation. All
construction areas not otherwise protected shall be planted with permanent vegetative
cover in accordance with the specifications within 15 working days after completion of
active construction.
MINIMUM AREAS TO BE DISTURBED: Only those areas necessary for timely and
proper completion of the project shall be stripped of native vegetation. The angle for
graded sloped and fills shall be no greater than the angle which can be retained by
vegetative cover or other adequate erosion control devices or structures. Slopes left
exposed will, within 21 calendar days of completion of any phase of grading, be planted
or otherwise provided with ground cover, devices, or structures sufficient to restrain

erosion. All other areas to be stabilized within 15 working days of cease of any phase of
activity.
PLACEMENT OF SEDIMENT CONTROL DEVICES: All devices (temporary sediment
fences, construction entrances, etc.) for sediment control shall be constructed prior to
beginning clearing and grubbing on the site.
FINAL COVER: As soon as practicable after finished grades have been established, all
operations in connection with establishing final ground cover shall be performed. Any
inactive disturbed ground area to remain denuded more than 15 working days shall be
temporarily seeded in accordance with the temporary seeding schedule as noted on the
plans. All slopes to be stabilized within 21 calendar days.

SEQUENCE OF CONSTRUCTION
1. Install temporary construction entrance as shown on erosion & sediment control plan.
2. Install perimeter controls (sediment trap, silt fence, etc.) as shown on the erosion &
sediment control plan. This step needs to be completed prior to upslope land disturbing
activities.
3. Once perimeter controls and sediment trapping measures are installed clear and grub
site within limits of disturbance.
4. Upon bringing the site to rough grade, stabilize all areas with temporary vegetation if
left undisturbed for 15 working days and all slopes within 21 calendar days.
5. Upon bringing the parking areas and road beds to subgrade elevations, stabilize the
areas by placing stone base as early as possible.
6. For temporary vegetative stabilization of all denuded areas see note referencing the
erosion control program and specifications.
7. After construction operations have ended and all disturbed areas have stabilized,
mechanical sediment controls shall be removed. Sediment from temporary sediment
trapping devices shall be disposed of by spreading on the site or hauling away if not
suitable for fill. All denuded areas are to be permanently stabilized with permanent
vegetation.
8. Prior to using the sediment trap as a dry detention basin/grassed swale it shall be
mucked out.

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GSP CONSULTING
Velocity Control:
BASIN #1 OUTLET
Q = 4.153 cfs (See provided calculations)
Velocity = 3.38 fps
New York DOT Dissipater Method For Use in Defined Channels: Zone 2
For 15-inch culvert
Upstream Width = 3.75 ft
Downstream Width = 5.0 ft
Length = 7.5 ft
Depth = 18 in
33 SF CLASS B RIPRAP PROVIDED
6626 Gordon Road, Unit C Wilmington, North Carolina 28411 tel: [phone] fax: [phone]

PRE -DEVELOPMENT FLOWS

GSP CONSULTING
PRE DEVELOPMENT FLOW RATES:
DRY DETENTION BASIN
Existing Drainage = 146,743 SF = 3.37 AC
Time of Concentration. = 5 min
Total Pre -Development Flow — (C)(I2-YR)(A)=(0.20)(5.88 IN/HR)(3.37 AC) = 3.96 CFS
Total Pre -Development Flow — (C)(h0-YR)(A)=(0.20)(7.23 IN/HR)(3.37 ACC = 4.87 CFS
Total Pre -Development Flow — (C)(I25-YR)(A)=(0.20)(8.15 IN/HR)(3.37 AC) = 5.49 CFS
UNDETAINED AREA
Existing Drainage = 116,025 SF = 2.66 AC
Time of Concentration = 5 min
Total Pre -Development Flow — (C)(I2-YR)(A)=(0.20)(5.88 IN/HR)(2.66 AC) = 3.13 CFS
Total Pre -Development Flow — (C)(I10-YR)(A)=(0.20)(7.23 IN/HR)(2.66 AC) = 3.85 CFS
Total Pre -Development Flow — (C)(I25-YR)(A)=(0.20)(8.15 IN/HR)(2.66 AC) = 4.34 CFS
TOTAL
Existing Drainage = 262,768 SF = 6.03 AC
Time of Concentration = 5 min
Total- Pre -Development Flow — (C)(I2-YR)(A)=(0.20)(5.88 IN/HR)(6.03 AC) = 7.09 CFS
Total Pre -Development Flow — (C)(Ii0-YR)(A)=(0.20)(7.23 IN/HR)(6.03 AC) = 8.72 CFS
Total Pre -Development Flow — (C)(I25-YR)(A)=(0.20)(8.15 IN/HR)(6.03 AC) = 9.83 CFS
6626 Gordon Road, Unit C Wilmington, North Carolina 28411 tel: [phone] fax: [phone]

POST -DEVELOPMENT FLOWS

Drainage Area
TOTALS
Drainage Area TOTAL
Drainage Area 262,768 sf
Drainage Area 6.03 ac
Impervious Area Calculation
Parking/Roads
31,881
Existing Impervious
5,220
Miracle Field/Playgrounds
41,361
Concrete/Walks
12,775
Total
91,237 sf
Total
2.09 ac
% Impervious
34.7%

CN CALCULATIONS
Dry Detention Basin
Total Site Area 146,743
Impervious 77,077 1.769
A -Soils 69,666 1.599
146,743 3.369
Undetained
Total Site Area
116,025
Impervious
14,160 0.325
A -Soils
101,865 2.338
116,025 2.664
98
39
70
98
39
46

13SP CONSULTING
PRE/POST SOTRMWATER CALCULATIONS:
Storm Evert
2-Year
10-`Fear
25-Year
Pre Development Runoff
7.094
8.723
9.833
Post Development Runoff
Dry Detention Basin #1
3.242
4.153
4.632
Undetained 10.335
3.110
4.863
Totals 1
3.577
1 7.263
9.495
6626 Gordon Road, Unit C Wilmington, North Carolina 28411 tel: [phone] fax: gio-799-6659

DRY DETENTION BASIN #1

DRY DETENTION BASIN
Drainage Area
Drainage Area
Drainage Area
Drainage Area
Impervious Area Calculation
Parking/Roads
Existing Impervious
Miracle Field/P!aygrounds
Concrete/Walks/Buildings
Total
Total
% Impervious
DA 1
1.46,743 sf
3.37 ac
18,621
4,629
41,361
12,466
77,077 sf
1.77 ac
'52.5%

Hydrograph Return Period Recap Hydraflow Hydrographs by I ntelisolve v9. 1
Hyd.
No.
Hydrograph
type
(origin)
Inflow
Hyd(s)
Peak Outflow (cfs)
Hydrograph
description
1-Yr
2-Yr
3-Yr
5-Yr
10-Yr
25-Yr
50-Yr
100-Yr
1
2
SCS Runoff
Reservoir
-------
1
-------
-------
6.246
3.242
-------
-------
-------
-------
13.88
4.153
17.29
4.632
-------
-------
-------
-------
DRY DETENTION BASIN
DRY DETENTION BASIN
Proj. file: DRY DETENTION BASIN.gpw
Thursday, Dec 8, 2011

Hydrograph Summary Report Hydraflow Hydrographs by Intelisolve v9.1
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
description
1
SCS Runoff
6.246
2
724
19,195
----
------
------
DRY DETENTION BASIN
2
Reservoir
3.242
2
732
19,194
1
36.01
2,948
DRY DETENTION BASIN
DRY DETENTION BASIN.gpw
Return Period: 2 Year
Thursday, Dec 8, 2011

Hydrograph Report
Hydraf low Hydrographs by Intelisolve v9.1
Hyd. No. 1
DRY DETENTION
BASIN
Hydrograph type
= SCS Runoff
Storm frequency
= 2 yrs
Time interval
= 2 min
Drainage area
= 3.370 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 4.50 in
Storm duration
= 24 hrs
* Composite (Area/CN) = [(1.769 x 98) + (1.599 x 39)] / 3.370
3
Thursday, Dec 8, 2011
Peak discharge = 6.246 cfs
Time to peak =
12.07 hrs
Hyd. volume =
19,195 cult
Curve number =
70*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type III
Shape factor =
484
DRY DETENTION BASIN
Q (cfs) Hyd. No. 1 -- 2 Year Q (cfs)
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0 00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
...,., Hyd No. 1 Time (hrs)

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 2
DRY DETENTION
BASIN
Hydrograph type
= Reservoir
Storm frequency
= 2 yrs
Time interval
= 2 min
Inflow hyd. No.
= 1 - DRY DETENTION BASIN
Reservoir name
= DRY DETENTION BASIN
Storage Indication method used.
4
Thursday, Dec S, 2011
Peak discharge = 3.242 cfs
Time to peak
= 12.20 hrs
Hyd. volume
= 19,194 cuft
Max: Elevation
= 36.01 ft
Max. Storage
= 2,948 cuft
DRY DETENTION BASIN
Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs)
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0 00
0 2 4 6
8 10
12 14
16 18 20
22 24
26
- Hyd No. 2 ----
Hyd No. 1
U-I ; I_ ! ;
Total storage used
2,948 cuft
Time (hrs)

Pond Report 5
Hydraflow Hydrographs by Intelisolve v9.1 Thursday, Dec 8, 2011
Pond No. 1 - DRY DETENTION BASIN
Pond Data
Contours - User -defined contour areas. Conic method used for volume calculation. Begining Elevation 34.77 ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00
34.77
00
0
0
0.23
35.00
513
39
39
1.23
36.00
6,195
2,830
2,869
2.23
37.00
24,565
14,364
17,233
Culvert /
Orifice Structures
Weir Structures
[A]
[B] [C]
[PrfRsr]
[A] [B]
[C] [D]
Rise (in)
= 15.00
12.00 0.00
0.00
Crest Len (ft)
= 16.00 0.00
0.00 0.00
Span (in)
= 15.00
12.00 0.00
0.00
Crest El. (ft)
= 36.77 0.00
0.00 0.00
No. Barrels
= 1
1 0
0
Weir Coeff.
= 3.33 3.33
3.33 3.33
Invert El. (ft) = 34.77
34.77 0.00
0.00
Weir Type
= Broad
Length (ft)
= 91.80
0.00 0.00
0.00
Multi -Stage
= Yes No
No No
Slope (%)
= 0.30
0.00 0.00
n/a
N-Value
= .013
.013 .013
n/a
Orifice Coeff.
= 0.60
0.60 0.60
0.60
Exfil.(in/hr)
0.000 (by Contour)
Multi -Stage
n/a
No No
No
TW Elev. (ft)
0.00
Note: CulverVOrifice outflows are analyzed under inlet (ic) and outlet (oc) control. weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge Table
Stage
Storage Elevation
Clv A
Clv B Civ C
PrfRsr Wr A
Wr 18 Wr C
Wr D Exfil User
Total
ft
tuft ft
cfs
cfs cfs
cfs cfs
cfs cfs
cfs cfs cfs
cfs
0.00
0 34.77
0.00
0.00
--- 0.00
--- --- ---
0.00
0.02
4 34.79
0.00
0.00 is ---
--- 0.00
---
0.00
0.05
8 34.82
0.00
0.01 is ---
--- 0.00
0.01
0.07
12 34.84
0.00
0.02 is ---
--- 0.00
---
0.02
0.09
16 34.86
0.00
0.04 is ---
0.00
--- ---
0.04
0.12
20 34.88
0.00
0.06 is ---
--- 0.00
---
--- --- ---
0.06
0.14
24 34.91
0.00
0.08 is ---
--- 0.00
--- --- ---
0.08
0.16
28 34.93
0.00
0.11 is ---
0.00
---
-
0.11
0.18
31 34.95
0.00
0.15 is
-- 0.00
--- --
--- ---
n IS
0.21
35 34.98
0.00
0.18 )c ---
- 0.00
--- --
0.18
0.23
39 35.00
0.00
0.22 is
- 0.00
--- ---
0.22
0.33
322 35.10
0.00
0.44 is
0.00
--- --
0.44
0.43
605 35.20
0.00
0.72 is
--- 0.00
--- ---
0.72
0.53
888 35.30
0.00
1.05 is ---
0.00
--- ---
--- --- ---
1.05
0.63
1,171 35.40
0.00
1.41 is
--- 0.00
--- ---
--- --- ---
1.41
0.73
1,454 35.50
0.00
1.79 is
0.00
--- ---
--- --- ---
1.79
0.83
1,737 35.60
0.00
2.16 is ---
0.00
--- ---
--- ---
2.16
0.93
2,020 35.70
0.00
2.50 is ---
--- 0.00
- ---
2.50
1.03
2,303 35.80
0.00
2.75 is ---
--- 0.00
--- ---
--- ---
2.75
1.13
2,586 35.90
0.00
3.00 is
--- 0.00
- -
3.00
1.23
2,869 36.00
0.00
3.23 is
--- 0.00
--- ---
--- --- ---
3.23
1.33
4,306 36.10
0.00
3.44 is
--- 0.00
--- ---
--- ---
3.44
1.43
5,742 36.20
0.00
3.65 is
--- 0.00
--- ---
--- --- ---
3.65
1.53
7,178 36.30
0.00
3.84 is
--- 0.00
--- ---
--- --- ---
3.84
1.63
8,616 36.40
0.00
4.02 is ---
0:00
--- ---
--- --- ---
4.02
1.73
10,051 36.50
0.00
4.19 is ---
0.00
--- ---
---
4.19
1.83
11,488 36.60
0.00
4.36 is ---
--- 0.00
--- ---
--- --- ---
4.36
1.93
12,924 36.70
0.00
4.52 is ---
0.00
--- ---
--- --- ---
4.52
2.03
14,360 36.80
0.29 oc
4.68 is ---
0.28
--- ---
--
4.95
2.13
15,797 36.90
2.51 oc
4.83 is ---
2.50
---
---
7.32
2.23
17,233 37.00
5.43 oc
4.97 is ---
5.43 s ---
--- --- ---
10.41

Hydrograph Summary Report
Hydraflow HydroRraohs by Intelisolve v9.1
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
description
1
SCS Runoff
13.88
2
724
41,498
---
------
DRY DETENTION BASIN
2
Reservoir
4.153
2
744
41,496
1
36.48
9,720
DRY DETENTION BASIN
i
rDRY DETENTION BASIN.gpw
Return Period: 10 Year
Thursday, Dec 8, 2011

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
DRY DETENTION BASIN
Hydrograph type = SCS Runoff
Storm frequency = 10 yrs
Time interval
= 2 min
Drainage area
= 3.370 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 7.00 in
Storm duration
= 24 hrs
* Composite (Area/CN) _ [(1.769 x 98) + (1.599 x 39)] / 3.370
7
Thursday, Dec 8, 2011
Peak discharge = 13.88 cfs
Time to peak =
12.07 hrs
Hyd. volume =
41,498 cult
Curve number =
70*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type III
Shape factor =
484
DRY DETENTION BASIN
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0 00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 1 Time (hrs)

Hydrograph Deport
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 2
DRY DETENTION
BASIN
Hydrograph type
= Reservoir
Storm frequency
= 10 yrs
Time interval
= 2 min
Inflow hyd. No.
= 1 - DRY DETENTION BASIN
Reservoir name
= DRY DETENTION BASIN
Storage Indication method used
8
Thursday, Dec 8, 2011
Peak discharge = 4.153 cfs
Time to peak
= 12.40 hrs
Hyd. volume
= 41,496 cuft
Max. Elevation
= 36.48 ft
Max. Storaae
= 9,720 cuft
DRY DETENTION BASIN
Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0 00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Time (hrs)
----- Hyd No. 2 --- Hyd No. 1 CAT-- � Total storage used = 9,720 cuft

Hydrograph Summary Report HydraflowHydrographsbylntelisolvev9.1
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Hyd.
volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
description
1
SCS Runoff
17.29
2
724
51,692
- --
------
DRY DETENTION BASIN
2
Reservoir
4.632
2
746
51,690
1
36.73
13,292
DRY DETENTION BASIN
DRY DETENTION BASIN.gpw
Return Period: 25 Year
Thursday, Dec 8, 2011

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
DRY DETENTION
BASIN
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Time interval
= 2 min
Drainage area
= 3.370 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 8.05 in
Storm duration
= 24 hrs
*Composite (Area/CN) [(1.769 x 98) + (1.599 x 39)] / 3.370
10
Thursday, Dec 8, 2011
Peak discharge = 17.29 cfs
Time to peak =
12.07 hrs
Hyd. volume =
51,692 cult
Curve number =
70*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type III
Shape factor =
484
Q (cfs)
DRY DETENTION BASIN Hyd. No. 1 -- 25 Year Q (cfs)
18.00 18.00
15.00 15.00
12.00 12.00
I<
r
9.00 9.00
6.00
6.00
3.00
3.00
0.00 "004 0.00
... .riw�wc._... sa.a-max '►
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 1 Time (hrs)

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 2
DRY DETENTION BASIN
Hydrograph type = Reservoir
Storm frequency = 25 yrs
Time interval = 2 min
Inflow hyd. No. = 1 - DRY DETENTION BASIN
Reservoir name = DRY DETENTION BASIN
Storage Indication method used.
11
Thursday, Dec S, 2011
Peak discharge = 4.632 cfs
Time to peak
= 12.43 hrs
Hyd. volume
= 51,690 cuft
Max. Elevation
= 36.73 ft
Max. Storage
= 13,292 cuft
Q (cfs) DRY DETENTION BASIN
Hyd. No. 2 -- 25 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
0 00
U 2 4
6 8 10
12 14 16 18 20 22 24
26
- Hyd No. 2
Y
---- Hyd No. 1
���w'=; Total storage used = 13,292 cult
Time hrs )

UNDETAINED

Drainage Area
UNDETAINED
Drainage Area DA 2
Drainage Area 116,025 sf
Drainage Area 2.66 ac.
Impervious Area Calculation
Road
1'3,260
Existing Impervious
591
Concrete/Walks
309
Total
14,160 sf
Total
0.33 ac
% Impervious
12.2%

Hydrograph Return Period Recap
Hvrlmflnw Hvrirnnranhc F... ,, ..n 4
Hyd.
No.
Hydrograph
type
(origin)
Inflow
Hyd(s)
Peak Outflow (cfs)
Hydrograph
description
1-Yr
2-Yr
3-Yr
5-Yr
107Yr
25-Yr
50-Yr
100-Yr
1
SCS Runoff
-------
-------
0.335
-------
-------
3.110
4.863
-------
------
UNDETAINED
8, 2011
Proj.
file: UNDETAINED.gpw
Thursday,
Dec

Hydrograph Summary Report
Hvdraflnw Hvrtrnnrnnhs by

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
UNDETAINED
Hydrograph type
= SCS Runoff
Storm frequency
= 2 yrs
Time interval
= 2 min
Drainage area
= 2.670 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 4.50 in
Storm duration
24 hrs
* Composite (Area/CN) ((0.330 x 98) + (2.340 x 39)] / 2.670
3
Thursday, Dec 8, 2011
Peak discharge = 0.335 cfs
Time to peak =
738 min
Hyd. volume =
3,026 cuft
Curve number =
46*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution
Type III
Shape factor =
484
Q (cfs)
UNDETAINED
cfs
Hyd. No. 1 -- 2 Year Q ( )
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
ii
G
i
r
ti
Ay,,,
WIR,y.�.l1�RM
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0 00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Summary Report z
:.._ ..., .

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
UNDETAINED
Hydrograph type = SCS Runoff
Storm frequency = 10 yrs
Time interval
= 2 min
Drainage area
= 2.670 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 7.00 in
Storm duration
= 24 hrs
61
Thursday, Dec 8, 2011
Peak discharge = 3.110 cfs
Time to peak =
726 min
Hyd. volume =
11,997 cuft
Curve number =
46*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type III
Shape factor =
484
* Composite (Area/CN) [(0.330 x 98) + (2.340 x 39)] / 2.670
UNDETAINED
Q (cfs) Q (cfs)
Hyd. No. 1 -- 10 Year
4.00
—r 4.00
3.00 3.00
2.00
2.00
1.00 1.00
0.00 �-- — 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Summary Report HydraflowHydrographsbylntelisolvev9.1
Hyd.
No,
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Hyd.
volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
description
1
I
SCS Runoff
4.863
2 724
i
16,939
----
---
------ UNDETAINED
UNDETAINED.gpw
Return Period: 25 Year
Thursday, Dec 8, 2011

Hydrograph Report
7
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
UNDETAINED
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Time interval
= 2 min
Drainage area
= 2.670 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 8.05 in
Storm duration
= 24 hrs
Composite (Area/CN) = [(0.330 x 98) + (2.340 x 39)] / 2.670
4.00
3.00
2.00
1.00
IZu ;e4u 360
Hyd No. 1
UNDETAINED
Hyd. No. 1 -- 25 Year
Thursday, Dec 8, 2011
Peak discharge = 4.863 cfs
Time to peak =
724 min
Hyd. volume =
16,939 cult
Curve number =
46*
Hydraulic length =
0 ft
Time of conc. (TO =
5.00 min
Distribution =
Type III
Shape factor =
484
Q (cfs)
5.00
4.00
3.00
2.00
1.00
000
480 600 720 840 960 1080 1200 1320 1440 1560.
Time (min)

100-YEAR

Hydrograph Return Period Recap HydraflowHydrographsbylntelisolvev9.1
Hyd.
No.
Hydrograph
type
(origin)
Inflow
Hyd(s)
Peak Outflow (cfs)
Hydrograph
description
1-Yr
2-Yr
3-Yr
5-Yr
10-Yr
25-Yr
50-Yr
100-Yr
1
2
SCS Runoff
Reservoir
-------
1
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
-------
23.77
22.51
DRY DETENTION BASIN
DRY DETENTION BASIN
Proj.
file: 100-YEAR.9pw
Thursday,
Dec 8, 2011

Hydrograph Summary Report G

Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 1
DRY DETENTION
BASIN
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 3.370 ac
Basin Slope
= 0.0 % .
Tc method
= USER
Total precip.
= 10.00 in
Storm duration
= 24 hrs
* Composite (Area/CN) [(1.769 x 98) + (1.599 x 39)] / 3.370
3
Thursday, Dec 8, 2011
Peak discharge = 23.77 cfs
Time to peak =
724 min.
Hyd. volume =
71,391 cuft
Curve number =
70*
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type III
Shape factor =
484
DRY DETENTION BASIN
Q (cfs) Hyd. No. 1 -- 100 Year Q (cfs)
24.00 24.00
20.00 20.00
16.00
16.00
12.00 12.00
it
8.00 8.00
C
4.00 tt 4.00
0.00 =� 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1
Time (min)

Hydrograph Report 4
Hydraflow Hydrographs by Intelisolve v9.1
Hyd. No. 2
DRY DETENTION
BASIN
Hydrograph type
= Reservoir
Storm frequency
= 100 yrs
Time interval
= 2 min
Inflow hyd. No.
= 1 - DRY DETENTION BASIN
Reservoir name
= DRY DETENTION BASIN
Storage Indication method used
Thursday, Dec 8, 2011
Peak discharge = 22.51 cfs
Time to peak
= 726 min
Hyd. volume
= 58,466 cuft
Max. Elevation
= 36.97 ft
Max. Storage
= 16,776 cuft
DRY DETENTION BASIN
Q (cfs) Hyd. No. 2 -- 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
0 00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
- Hyd No. 2 ----- Hyd No. 1 C- �Tl Total storage used = 16,776 cuff

Pond Report
5
` Hydraflow Hydrographs by Intelisolve v9.1
Thursday, Dec 8, 2011
Pond No. 1 - DRY DETENTION BASIN
Pond Data
Contours - User -defined contour areas. Conic method used for
volume calculation. Begininq
Elevation
34.77
ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft)
Incr. Storage (cult)
Total storage (cult)
0.00 34.77 00
p
0.23 35.00
1.23
39
0
39
.
3600 6,195
2.23 36.00
2,830
2,869
24,565
14,364
17,233
Culvert / Orifice Structures
Weir Structures
[A] [B] [C] [PrfRsr]
[A] [B]
[C]
[D]
Rise (in) = 0.00 0.00 0.00 0.00
Span (in) 0.00
Crest Len (ft)
= 75.00 0.00
0.00
0.00
= 0.00 0.00 0.00
No. Barrels = 0
Crest El. (ft)
= 36.77 0.00
0.00
0.00
0 0 0
Invert El. (ft) = 0.00 0.00 0.00 0.00
Weir Coeff.
= 3.33 3.33
3.33
3.33
Length (ft) = 0.00 0.00 0.00 0.00
Weir Type
Multi -Stage
= Broad
= No No
Slope (%) = 0.00 0.00 0.00 n/a
No
No
N-Value = .013 .013 .013 Na
Orifice Coeff. = 0.60 0.60 0.60 0.60
Exfil.(in/hr)
= 0.000 (by Contour)
Multi -Stage = n/a No No No
TW Elev. (ft)
0.00
Note: Culvert/orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge Table
Stage Storage Elevation Clv A Clv B Clv
ft tuft
C PrfRsr Wr A
Wr B Wr C
Wr D
Exfil User Total
ft cfs cfs cfs
cfs cfs
cfs cfs
cfs
cfs cfs cfs
0.00 0 34.77 -
--- 0.00
0.02 4 34.79 --- ---
0.00
---
0.00
0.05 8 34.82
0.00
- -
0.07 12 34.84
"" 0.00
---
0.00
---
- - 0.00
- -
• 2 20 34.88
0.00
---�'
---
�' 0.00
--
0.14 24 34.91 --
--- 0.00
-
-"
--- 0.00
- - -
0.16 28 34.93 -
_ 0.00
- '--
---
"---- 0.00
- ---
0.18 31 34.95
0.00
-----
-"
--- -- 0.00
-- ___
0.21 35 34.98
_�-__- 0.00
--
"-"
"--
"' ---0.00
0.23 39 35.00 --- ---
-- 0.00
--- ---
---
-- --- 0.00
-
0.33 322 35.10
-- 0.00
--- ---
---
"' --- 0.00
0.43 605 35.20
-'-
-"
"' 0.00
0.53 888 35.30
---
_-
---
-- - 0.00
0.63 1,171 35.40
-
-'
0.73 1,454 35.50
_
--
- 0.00
-" ---
0.83 1,737 35.60
__ 0.00
-
- "
---
0.00
0.93 2,020 35.70 ---
0.00
--"
--"
-- 0.00
1.03 2,303 35.80 ---
0.00
---
--- 0.00
1.13 2,586 35.90 - -
0.00
---
--- --- 0.00
1.23 2,869 36.00 -_- -
0.00
_
--- 0.00
- ---
1.33 4,306 36.10 ---
0.00
-"
- --- 0.00
1-43 5,742 36.20
0.00
---
--- --- 0.00
'-
1.53 7,178 36.30 ---
0.00
'"'
--- 0.00
-
1.63 8,615 36.40 -
0.00
---
0.00
1.73 10,051 36.50 __ - ---
--- 0.00
---
--- 0.00
--- ---
1.83 11,488 36,60 ---
--- 0.00
---
"---- 0.00
--- ---
1.93 12,924 36.70 ---
- 0.00
"--
'"' --- 0.00
2.03 14,360 36.80 --_ ti _
0.00
__ --
'-' --- 0.00
-- --
2.13 15,797 36.90
1.30
- -1.30
--- ---
2.23 17,233 37.00 -
--- 11.70
- - 11.
--- ---
--- 27.55
_
-- -- 27.55

SWALES

Drainage Area
SWALE #1
Drainage Area 54,292 sf
Drainage Area 1.25 ac
Impervious Area Calculation
Parking
13,284
Miracle Field
16,357
Concrete/Walks
4,320
Total
33,961 sf
Total
0.78 ac
% Impervious
62.6%
10-Year Post Dev. Peak Flow
Intensity 7.23 in/hr
C-Factor 0.69
Q=C*I*A 6.20 cfs
Drainage Area
SWALE #2
Drainage Area 90,050 sf
Drainage Area 2.07 ac
Impervious Area Calculation
Parking/Roads
5,643
Existing Impervious
4,628
Miracle Field/Playgrounds
21,623
Concrete/Walks
6,022
Total
37,916 sf
Total
0.87 ac
% Impervious
42.1%
10-Year Post Dev. Peak Flow
Intensity 7.23 in/hr
C-Factor 0.54
Q=C*I*A 8.14 cfs

SWALE #1
Worksheet for Trapezoidal Channel
Project Description
Worksheet
SWALE #1
Flow Element
Trapezoidal Cha
Method
Manning's Formi
Solve For
Channel Depth
Input Data
Mannings Coeffin.011
Channel Slope
0.50 %
Left Side Slope
5.00 H : V
Right Side Slope
5.00 H : V
Bottom Width
11.00 ft
Discharge
6.20 ofs
Results
Depth
0.18 ft
Flow Area
2.1 ft2
Wetted Perim(
12.84 ft
Top Width
12.80 ft
Critical Depth
0.21 ft
Critical Slope
0.31 %
Velocity
2.90 ft/s
Velocity Head
0.13 ft
Specific Enerc
0.31 ft
Froude Numb.
1.25
Flow Type
Supercritical

SWALE #2
Worksheet for Trapezoidal Channel
Project Description
Worksheet
SWALE #2
Flow Element
Trapezoidal Cha
Method
Manning's Formi
Solve For
Channel Depth
Input Data
Mannings Coeffic).011
Channel Slope
0.41 %
Left Side Slope
5.00 H : V
Right Side Slope
5.00 H : V
Bottom Width
11.00 ft
Discharge
8.14 cfs
Results
Depth
0.22 ft
Flow Area
2.7 ft2
Wetted Perim(
13.28 ft
Top Width
13.24 ft
Critical Depth
0.25 ft
Critical Slope
0.29 %
Velocity
3.00 ft/s
Velocity Head
0.1^ ft
Specific Enerc
0.36 ft
Froude Numb,
1.17
Flow Type
Supercritical

Baker, Chris
From: Wolf, Cindee ([e-mail]]
Sent: Thursday, January 12, 2012 1:52 PM
To: Baker, Chris
Subject: Olsen Park Permit #SW8 090217
Attachments: Olsen ParkExhibit. pdf
Chris,
The current request for plan revision to the last permit, issued November 1, 2010, is to:
1. Move the location of the "Future Playground Area" from adjacent to the picnic shelter to the northern area of the site
between ball fields # 4 & #5.
2. Increase the line -item for "Other On -site" (which was to include the playground & Miracle field) from 50,318 s.f. to
86,017 s.f. due to increase in the size of the field & addition of an access drive and parking area.
3. Reducing the line -item for "Future" to 626,541 s.f.
Please do not hesitate to contact me if you have questions or need additional information. Thanks for your assistance.
Cindee Wolf
WITHERG 6CRAVENEL
1410 Commonwealth Drive, Unit 101 Wilmington, NC 28403
Phone: [phone] Fax: [phone]
Direct: 910.509.65051 Mobile: [phone]
cwo�withersravenel.com
www.vAthersravenel.com
NOTICE OF CONFIDENTIALITY AND NONDISCLOSURE: This electronic message, which includes any attachments and other
documents referred to herein, contains information from Withers & Ravenel, Inc. that may be proprietary or confidential. The
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rights are licensed, transferred or otherwise granted by the transmission of this electronic message by Withers & Ravenel, Inc. or
receipt of this message by the recipient or any other party.

Co [etenessi Review Checklist
Project Name: ACt,� X44:-CD /Oso2--��-�.r Received Date
Project Location: ki�N i�cn::'�%1� Accepted Date
Rule(s) M2008 Coastal F-11995 Coastal
Type of Permit: New or Mod or PR
Density: HD or LD" Type: omi
: _](% OK?)\'--1 Stream Chat"
Subdivided?: Subdivision or Single Lot
Phase II (WiRO )
Existing Permit # (Mod o P
or Residential
MSA Map
— I �^ORW Map
� it
"Universal [D1988 Coastal
TR)--F--lPECert on File?
MNCG:
r7Offsite to SW8
Exempt
Paperwork
ppiement(s) (1 original per BMP) BMP Type(s):
&M with correct/original signatures (1 original per BMP except LS/VFS and swales)
pplication with correct/original signatures
Corp or LLC: Sig. Auth. per SoS or letter Note to Reviewer:
$ 5 (within 6mo) I�i L�ilnC. JC`�,'"n
�c R"144LLCCYc
"
Soils Report with SHWT
CIculations (signed/sealed)
No obvious errors
EiDensity includes common areas, etc
Deed Restrictions, if subdivided:
ned & Notarized
L_JCorrect Template (Comm/Res & HD/LD) or Dec Covenants & Rest
Plans --
2 Sets Details (roads, cul-de-sacs, curbs, sidewalks, BMPs, Buildings, etc)
❑Grading ®Wetlands: Delineated or No Wetlands
Vicinity Map 11 Layout (proposed BUA dimensions)
Legend ElDA Maps El Project Boundaries
Infiltration Wet Pond Offsite _
Soils Report Soils Report PE Cert for Master Lot #:
SHWT: SHWT:Deed Rest for Master Lot # M atches Master
Bottom: PP: BUA Permitted (Master): sf
Visited: BUA Proposed (Offsite): sf
Additional Information:
Permitted Proposed: Proposed: OrnnncmA-
BUA (sf)
DA (sf)
PP (el)
SHWT (el)
Depth (ft)
SA (sf)

GSP CONSULTING
TO:
6626 Gordon Road, Unit C
WILMINGTON, NORTH CAROLINA, 28411
[phone]
FAX [phone]
NC Division of Water Quality
127 Cardinal Drive Ext.
Wilmington, NC 2840
LETTER OF TRANSMITTAL
DATE 12 08 11
JOB NO.
2011-000
ATTENTION
PHONE#
RE:
"Miracle Field
Stormwater permit
OTU
WE ARE SENDING YOU ❑ Attached ❑ Under separate cover via the following items:
® Fee Check ® Permit Applications ® Plans ® Calculations
❑ Specifications
❑ Copy of Letter ❑ Change order ❑ Diskette ❑
COPIES
DESCRIPTION
2
Sets of plans & calculations for state stormwater permit
2
Stormwater Management Permit ,,., � s, _ �; �- � ^„ts��` l c.
z
Grassed Swale Supplement & Checklist
THESE ARE TRANSMITTED as checked below:
® For approval ❑ Approved as submitted ❑ Resubmit copies for approval
❑ For your use ❑ Approved as noted ❑ Submit copies for distribution
❑ As requested ❑ Returned for corrections ❑ Return corrected prints
❑ For review and comment ❑
❑ FOR BIDS DUE ❑ PRINTS RETURNED AFTER LOAN TO US
REMARKS:
COPYTO: File
SIGNED: - Garry S. Pape, P.E.
If enclosures are not as noted, kindly notify us at once.