SW8060249_COMPLIANCE_20060516

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
❑ HISTORICAL FILE
COMPLIANCE EVALUATION INSPECTION
DOC DATE
WYYMMDD

DETENTION POND ANALYSIS FILE NAME: G:\DATA\WPDATA\WQS\POND1060249.WK1
PROJECT#: SW8 060249 REVIEWER: P.Bartlett
PROJECT NAME: Ness Commons, Lot#1-43 (Shop Ctr/WilcoHess)
DATE: 16-May-06
Receiving Stream: Ness Creek Class: C; SW
Drainage Basin: Cape Fear Index No. 18-74-62
Site Area 8.00 acres
square feet 8.00 acres
Drainage Area 048a Area =
IMPERVIOUS AREAS
Lot 1: Bldg
3500-00
square feet
Lot 1: prkg
22661.00
square feet
Lot 1: sidewalk
500.00
square feet
Lot 1: other
539.00
square feet
Lot 2: future
27200.00
square feet
Lot 3- future
185180.00
square feet
TOTAL square feet
SURFACE AREA CALCULATION
% IMPERVIOUS 68.75%
Des. Depth 5
TSS: 90
Rational C
0.95
0.95
0.95
0.95
0.95
0.95
Rational Cc= 0.72
SA/DA Ratio 4.91%
Req. SA 17119 sf
Prov. SA ii18733 sf
VOLUME CALCULATION place a "1" in the box if Rational is used
Rational ?*
FOREBAY
Des. Storm
1:7:77:::777: 'T 00] inches
Perm. Pool Volume=
43697
Rv=
0.67
Req. Forebay Volume=
8739.4
Bottom
24 msl
Provided Volume=
8396.00
Perm. Pool
29.40i msl
Percent=
Design Pool
30 msl
Design SA
22250 sf
Req. Volume
cf
SA @ =
1651
18733 22250.00
Prov. Volume
20743 cf
Elevation=
24
29 30-00
ORIFICE CALCULATION
Avg. Head =
0.46 ft
Q2 Area =
4.96
sq. in.
Flow Q2, cfs
0.112 cfs
Q5 Area =
1.99
sq. in.
Flow Q5, cfs
0.045 cfs
Orifice Area
3.14
sq. in.
No. of Orifices
'::'
:A
Q=
0.071
cfs
Diameter, inches
weir H x W in
x
in
Drawdown
days
COMMENTS
Surface Area , Volume and Orifice are within Design Guideline:

REVISED
RUNOFF and STORAGE CAL CULA TIONS AND
WET DETENTION POND SIZING
for
WilcoHess C-Store Site
Castle Hayne Road
April 2006
By: RIGHT ANGLE ENGINEERING, P.C.
2 12 Prince55 Street
Wlmincgton, North Carolina 28401
(91 O) 251-8544
[phone] (fax)
SEAL
PE 0239, r
A�G1NE�` P��=
NE
-owes$

forebay
Forebay volumes
#units=Elevation,ft,Area,ft2,volume,ft3,volume,ft3
# Elev
Area
Cumml Avg
Cumml Conic
# ft
ft2
ft3
ft3
29.0000
3938.7395
8395.6836
8203.4120
27.0000
1684.7109
2772.2332
2737.1297
26.0000
1138.0756
1360.8399
1334.6421
25.0000
662.4773
460.5635
445.0236
24.0000
258.6496
0.0000
0.0000
Page 1

main
main Section volumes
#unitS=Elevation,ft,Area,ft2,volume,ft3,volume,ft3
# Elev
area
Cumml Avg
Cumml Conic
# ft
ft2
ft3
ft3
29.0000
14794.4123
35301.2221
34744.7064
27.0000
7424.4724
13082.3374
12945.1221
26.0000
5342.2929
6698.9547
6590.2293
25.0000
3331.3667
2362.1249
2292.7877
24.0000
1392.8830
0.0000
0.0000
Page 1

R UNOFF and STORA GE CAL CULA TIONS AND
WET DETENTION POND SIZING
for
WilcoHess C-Store Site
Castle Layne Road
April 2006 1 APR 1 2 Z006
By: RIGHT ANGLE ENGINEERING, P.C.
2 1 2 Prince5s Street
Wilmington, North Carolina 28401
(910) 25 1-8544
(J 10) 251-2208 (fax)
SEAL

1,
Right Angle Engineering, P.C. DETENTION POND SIZING CALCULATIONS 4/12/2006
Drainage Area =
8.00 acres
Impervious Area =
5.50 acres
Percent Impervious =
68.8%
Pond depth =
5 ft
TSS removal =
90%
M SA/DA =
5.00%
(No vegetative filter required)
Receiving Stream Class:
sc Required Runoff Storage Depth =
Minimum Required Surface Area at Permanent Pool:
=
0.0500
8.00 '
Minimum Required Volume (Schueler Method, see calculations):
Rv = 0.05 + 0.009
(68.75) =
0.67
Volume = (1"112")
0.67
8.00 ' 43560 =
Surface Area Provided at PP =
18500 ✓ >
17424 @
Need at Least
19421 ft�
of storage/ 18500
Therefore, use
Elevation of Temporary Pool =
29 ✓ +
1.00 ft =
Surface Area at
30 ,/ =
22250 sf
Storage Volume Provided =
20375 ✓ f13
Calculate Forebay Volume
Permanent Pool Total Volume =
41524 cf
Forebay Volume Required =
(.2' 41524
) _ 8305 cf
Forebay Volume Provided =
6905 CIF or
E-9/.
Orifice Sizing
Qz = 19421
Q5 = 19421 1
Choose a 2" Circular Orifice, Average Head =
0.112 cfs >
Choose a 1" Circular Orifice, Average Head =
0.112 cfs >
Therefore, use a 2" Orifice
1 inch
43560 =
19421 ft'
Elev. 29 ft
1.05 ft
1.00 ft
30 ft
17424 sf
172800
= 0.112
cfs (Flowrate required for a 2 day drawdown)
432000
= 0.045
cfs (Flowrate
required for a 5 day drawdown)
az =
0.03448
a5 =
0.013791
(1.00-(1I2)*(2in/12)12 =
0.458
ft
dia (in) = 2
a = pi(r^2)
0.0218
sf
Q = Ca(2gh)^.5 =
0.0711
cfs
0.0711 cfs
>
0.045
cfs
(1.00-(112)'(4in112)12 =
0,479
ft
dia (in) = 1
a = pi(r^2)
0.00545
sf
Q = Ca(2gh)6.5 =
0.01818
cfs
0.0182 cfs
<
0.045
cfs
Page 1

Right Angle Engineering, P.C. DETENTION POND SIZING CALCULATIONS 4/12/2006
Pre -Development 25 Year Storm
Q=CIA =
C =
0.2
1 =
7.14
Tc =
10.00
A =
8.0
Q = CIA =
11,43 cfs
Post -Development 25 Year Storm
Q = CIA =
C =
0.681
1 =
7.14
Tc =
10.00
A =
8.0
Q = CIA =
38.93 cfs
Size Outlet Pipe
D = 16(Qnl(s1.5))1(318)
S = 1.92%
n = 0.013
D (theoretical) = 26.0 in
D (actual) = 30.0 in
Size Emergency Spillway
impervious 0.00%
pervious = 100.00%
t (in/hr) = g/(h+T) for T=5 to 120 minutes
impervious 68.8%
pervious = 31.25%
1(ir1hr) = g/(h+T) for T=5 to 120 minutes
Channel Lining: Grass Lined
n= 0.010
34 ft. 1 S= 0.50%
3 Q Mannings (cis)= 9A9
�5.0 ft—�
Length= 10 fi
Velocity-- 4.54 ft/s
Depth with Freeboard= 0.34 ft
Page 2

Temporary Pool Volume
#units=Elevation,
# Elev
# ft
30.0000
29.0000
ft,Area,ft2,vo
Area
22250.3442
19287.1977
temppool
lume,ft3,volume
Cumml Avg
/ f_t 3
Y 20768)7709
0.0000
Page 1
, ft3
Cumml Conic
f-t
20751)1334
0.0000

mai n
Main Pond Volume
#units=Elevation, ft,Area,ft2, Vol ume,ft3,Vol ume,ft3
# Elev
Area
Cumml Avg
Cumml Conic
# ft
f�2
_ft3
ft3
29.0000
15075> 6398
L4619).7086
33882.8233
27.0000
6906.6828
12637.3859
12425.2407
26.0000
4817.1998
6775.4446
6594.5829
25.0000
2Z92,.2730
2970.7082
2835.5747
24.0000
(�1478 2522
835.4456
734.8428
23.0000
192.6389
0.0000
0.0000
Page 1
u7
415 /G.�%

Forebay Volume
#Units=Elevation
# El ev
# ft
29.0000
27.0000
26.0000
25.0000
24.0000
23,0000
ft,Area,ft2,Vo
Area
,f 2
350_3).6939
12'82.3992
821.4375
431.9941
c212>. 2104
24,3600
forebay
lume,ft3,Volume,
Culilml Avg
t3
6905).1146
21f9.0215
1067.1032
440.3874
118.2852
0.0000
Page 1
ft3
Cumml Conic
ft3
6682.1211
2078.2581
1034.8599
418.4834
102.8230
0.0000

DESIGN NARRATIVE FOR HIGH DENSITY PROJECT
AT CORE INVESTORS 8 AC. COMMERCIAL BUILDING SITE
CASTLE HAYNE ROAD
NEW HANOVER COUNTY, N.C.
October 2005
TABLE OF CONTENTS
1.0 PROJECT DESCRIPTION
2.0 SITE DESCRIPTION
;:0 ADJACENT PRDrc
4.0 DRAINAGE CONSIDERATIONS
5.0 EROSION CONTROL CONSIDERATIONS
6.0 CONSTRUCTION SCHEDULE
7.0 VEGETATION PLAN
8.0 MAINTE^DANCE PLAN
APPENDIX
RUNOFF CALCULATIONS
PIPE CALCULATIONS
ww
9___j
U231 lNE
� Y
P�+
I moo
Core Investors Commercial Building Site
Castle Hayne Road
October 2005

1. Projcect Description: The Project is proposed to be construction of a 3500 SF
gas station/convenience store with fuel islands, parking lot, asphalt entrance road, and
storm water system for the entire 8 acre site. The land disturbing activity associated with
the project will consist of clearing and grubbing of vegetation, preservation of existing
trees, grading of the site, and sediment and erosion control measures such as a silt
fence, gravel 'construction entrance, inlet protection, and wet detention pond. Also
included in the project will be storm piping to collect the parking drainage and future
areas and direct it to the wet detention pond. The total area which will be disturbed for
this project is 3.5 acres. Total impervious area allowed for the entire site will be 239,580
SF for the proposed construction and also make a future allowable impervious for
prospective development.
2. Site Description:, The project site is in New Hanover Co., NC, located on Castle
Hayne Road approximately 2000 feet north of the intersection of Kerr Ave. The property
on which the development will take place is currently owned by Core Investors of ,vl�'
Winston-Salem, NC.
On site soils consist mainly of Baymeade, and Leon. These soils are mainly loamy, fine
sands.
There are no existing wetlands onsite. Existing drainage ditches define the rear property
line and the south property line and provide surface water runoff for the site. These
ditches will be left intact.
General slope of the site is from northeast to southwest towards the back of the site.
Land use in the vicinity is residential, rural agricultural, and commercial.
3. Adjacent Property: The areas adjacent to the project site are residential and
commercial areas.
4. Drainage Considerations:- There are two major drainage features existing on
the site. The site is mostly flat with slight slope from northeast to southwest. A typical
18" driveway crossing pipe will be installed at the entrance on Castle Hayne Road and
will only carry drainage along the road side ditch. The parking area will have one catch
basin and an 18" outlet pipe to direct the runoff to the collection system. The collection
system will -be sized for -future development and carry the flow to the wet detention -basin. I
The basin is sized to provide sufficient runoff capacity for the entire allowable impervious
area. The wet detention basin is to provide detention of the pre -construction and post -
construction runoff difference and meet the 90% TSS water quality requirements. The
amount of retention was based on the Type III rainfall distribution of the 25 year, 24-hour
storm. Calculations are provided.
5. Erosion Control Considerations: The following erosion control measures are
used on this project:
1. Temporary Gravel Construction Entrance/Exit
Core Investors Commercial Building Site
Castle Hayne Road
October 2005

To prevent sediment from leaving the site, temporary gravel construction entrances
should be installed where the access road enters the site and instersects with
Castle Hayne road. For dimensions and specifications, see construction details.
2. Land Grading
The existing slope of the site is from northeast to southwest towards the back of
the lot. Most of the disturbed areas on the site will sheet flow to the existing
drainage patterns on the site and to the catch basins.
3. Silt Fence
Silt fence should be installed prior to clearing and grading activities. Silt fence
should be checked routinely. If needed, silt fence should be cleaned and replaced
if damaged. See Construction Detail for dimensions and specifications.
4. Wet Detention Basin
A wet detention basin will be constructed for long term runoff pollutant control, and
this area will be used as a sediment basin during construction. Outlet control
structure with rip rap energy dissapator will be installed when basin is excavated
and 30' sodded vegetated filter will be placed after the rip rap to provide additional
filtering prior to discharge into the existing ditch.
6. Construction Schedule_
1. Obtain plan approval and other applicable permits.
2. Hold pre -construction meeting at least one week prior to beginning construction.
3. Install temporary construction entrance/exits.
4. Before clearing and grading of the site, install silt fencing, detention basin with outlet
structure, and clean and replace as necessary.
5. Begin clearing and grading of the site.
6. Install storm piping.
7. Install new roadway.
8. Sod/Seed, mulch, and tack immediately to establish proper vegetation.
9. All erosion and sediment control practices will be inspected weekly and after each
rainfall event_ Needed repairs will be made immediately.
10. After the entire covered area is stabilized, all temporary measures will be removed
and permanent vegetative repairs to be completed.
7. Vegetation Plan:
1. After complete stabilization of the entire covered area, top cover soils will be
roughened by making 1 "-2 deep grooves perpendicular to the slope.
Core Investors Commercial Building Site
Castle Hayne Road
October 2005

2. Spread lime (agricultural limestone) evenly over the area at a rate of 1.5 tons/acre;
spread 10-10-10 fertilizer at a rate of 1000 lb/acre and incorporate into the top 6" of
soil.
3. Loosen surface prior to applying seed.
4. Broadcast seed at recommended rates.
5. Rake seed into the soil and lightly pack to establish good contact.
6. Mulch with 4000 lb/acre grain straw or equivalent and anchor by weighted farm disc
set nearly straight or other mulch anchoring tool.
7. Mow as needed and refertilize in late winter or early spring by topdressing with 10-
10-10 fertilizer.
8. Graded surfaces shall not be exposed without grass coverage for more than 15
days. If grades are not complete and exposure is more than 15 days, temporary
seed with rye grain at 50 lb/acre.
8. Maintenance Plan:
1. Contractor shall maintain all sedimentation and erosion control devices during
construction.
2. All devices shall be checked after each rain event and weekly. Repairs shall be
made immediately when detected.
3. Any deficiencies shall be brought to the immediate attention of the Engineer.
Seed Types and Application Rate ! Schedule
Temporary Seeding
Grass Type
Amount/ 1000 SF
Time of Seeding
Initial
Rye Grain
1-2 Ibs
Nov. —Jan.
25 Ibs 10-10-10
Brown Top Millet
1-2 Ibs
June —Au ,
25 lbs 10-10-10
Core Investors Commercial Building Site
Castle Hayne Road
October 2005

Permanent Seeding
Grass Type
Amount
Time of
Initial
Fertilization 1
Fertilization 1
Fertilization /
/1000
Seeding
1000 sf
1000 sf
1000 sf
sf
Maintenance
Maintenance
maintenance
Bermuda,
1-2 lbs
Apr. —
25 lbs
March -April
Each 4-8
Aug. -Sept -
Common
June
10-10-10
12 lbs
Weeks
12lbs
10-10-10
1-2 lbs N.
10-10-10
Fescue, Tall
5-7 lbs
Sept. —
25 ibs
Feb -March
May & Dec.
Sept. -Oct -
(Kentucky
Oct.
10-10-10
12 lbs
'/2 to 1 lb. n.
12 lbs
31)
Feb. —
10-10-10
10-10-10
Oct.
Sericea
1-2 lbs
March —
25 lbs
Feb -March
%to 1 lb. N.
NIA
Lespedeza
Apr.
10-10-10
5lo es
** Bermuda Sod Where shown on the plans.
END OF PLAN
Core Investors Commercial Building Site
Castle Hayne Road
October 2005