SW6120801_Stormwater Report_20120822

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51,1 G 12 o:�-O I
LOT 1, AVERITT PROPERTIES
CUMBERLAND COUNTY, NORTH CAROLINA
STORMWATER / EROSION CONTROL NARRATIVE
Prepared for:
FULLBLOCK, LLC
321 NORTH FRONT STREET
WILMINGTON, NC 28401
Prepared by:
PA.RAMC)tJ-T*,4TE
J= fV 1--71 1 fV F= 1= 1—� 1 N CD 1 N [:
5911 Oleander Drive, Suite 201
Wilmington, NC 28403
Project n12113.1"E
August 2012
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LOT 1, AVERITT PROPERTIES
CUMBERLAND COUNTY, NORTH CAROLINA
Project #12113.PE
Table of Contents
Design Narrative
Proposed Improvements
Maintenance
Erosion and Sedimentation Control Specification
Soils Map
USGS Map
Calculations
Page

LOT 1, AVERITT PROPERTIES
CUMBERLAND COUNTY, NORTH CAROLINA
Project #12113.PE
DESIGN NARRATIVE
Fullblock, LLC proposes to construct a warehouse building at the corner of Airport Road (S.R.
2260) and Aviation Drive (a private street) within Cumberland County, NC. As a result, please
find this design narrative, plans, and supporting calculations sufficient for the stormwater
duality and quantity control according to NCDENR and Cumberland County regulations. The
address of the property is 185 Airport Road, Fayetteville, NC 28306 with a latitude and
longitude of 34' 59' 51" N, 78' 53' 31" W (Parcel ID# 0435-24-2118; Deed Book 8509 page 169).
There is currently no existing impervious across the property and the ground cover is mostly
fair open space with a few sparse trees. Soils consist of Wagram-Urban complex (WgB) and
Lakeland -Urban complex, according to the provided soils map from NRCS and have a HSG
classification of A. According to the attached USGS map, the project drains to Big Sandy Run
which has a stream classification of C (18-31-25) and is within the Cape Fear River Basin.
PROPOSED IMPROVEMENTS
It is proposed that all runoff resulting from impervious surfaces will be collected by a storm
drainage system and then be conveyed to a wet detention pond where stormwater quality
requirements gill be met. The pond has been designed to NCDENR requirements which
include a forebay and a drawdown orifice at permanent pool. Stormwater from greater storm
events will be allowed to exit the wet detention pond by means of a riser barrel outlet structure
and a secondary spillway during emergency situations.
In regard to erosion control, please find that it is proposed to use the wet detention pond as a
sediment basin during construction activities. As a result, please find that we have designed
the sediment basin to NCDENR land quality requirements (per NCDENR Erosion and
Sediment Control Design and Planning Manual (June 1.,", 2006)) and have also added a skimmer
to the draw down orifice at permanent pool in order to prevent sediment from leaving the
outlet structure prior to the site being fully stabilized. Other than the sediment basin, it is
proposed to install inlet protection to the storm drain inlets to prevent sediment from entering
the system as well as silt fence and temporary construction entrances along Aviation Parkway.
Please see sheet C-1.0 for all Erosion Control and Sequence of Construction notes. The
sedimentation and erosion control design will commence.as depicted in the construction
sequence. Please find all reference material and stormwater / erosion control calculations in the
following pages of this report. Note that some calculations have also been located on the plans
for easy reference during construction.

MAINTENANCE
Contractors shall be responsible for periodic inspection and maintenance of all indicated
erosion control devices in accordance with the plans and specifications. In addition, inspection
and any necessary maintenance will be required immediately following any significant storm
event. Any erosion control measure that fails to function as intended shall be repaired
immediately. Upon completion of construction and the establishment of stabilized ground
cover, the property owner shall be responsible for any on going site maintenance.

EROSION AND SEDIMENTATION CONTROL SPECIFICATION
PART 1 - GENERAL
1.1 RELATED DOCUMENT
A. Drawings and general provisions of the Contract, including General and Supplementary
Conditions and Division 1 Specification Sections, apply to this Section.
1.2 WORK INCLUDED
A. Contractor shall take every reasonable precaution throughout construction to prevent the
erosion of soil and the sedimentation of streams, lakes, reservoirs, other water impoundments,
ground surfaces, or other property as required by State and local regulations.
B. Contractor shall, upon suspension or completion of land -disturbing activities, provide
protection covering for disturbed areas. Permanent vegetation shall be established at the
earliest practicable time. Temporary and permanent erosion control measures shall be
coordinated to assure economical, effective, and continuous erosion and sediment control
throughout the construction and post construction period.
1.3 RELATED SECTIONS
A. Related Sections — The following Sections contain requirements that relate to this Section:
1. 01011 — Existing Underground Utilities
2. 01015 — Special Conditions for this Contract
3. 01070 — Shop Drawings, Project Data & Samples
4. 02200 — Earthwork, Excavation Trenching, and Backfilling
5. 02230 — Site Clearing
6. 02240 -- Dewatering
7. 02485 — Seeding General Areas
1.4 REGULATORY REQUIREMENTS
A. Contractor shall be responsible for prevention of damage to properties outside the construction
limits from siltation due to construction of the project. The Contractor will assume all
responsibilities to the affected property owners for correction of damages that may occur.
Erosion control measures shall be performed by the Contractor, conforming to the requirements
of, and in accordance with plans approved by applicable state and local agencies and as per the
erosion control portion of the construction drawings and these specifications. The Contractor
shall not allow mud and debris to accumulate in the streets. Should the Contractor pump water
from trenches during construction, appropriate siltation preventative measures shall be taken
prior to discharge of pumped water into any storm drain or stream.

PART 2 - PRODUCTS
2.1 Open mesh biodegradable mulching cloth,.
2.2 Fertilizer shall be 10-10-10 grade or equivalent
2.3 Lime shall be dolomitic agricultural ground 1 limestone containing not less than 10 percent
magnesium oxide.
2.4 Phosphate shall be 20 percent super phosphate or equivalent.
2.5 Provide grass seed mixture as shown on the plans.
2.6 Silt fence shall consist of non -biodegradable filter fabric (Trevira, Mirafi, etc.) wired to
galvanized wire mesh fencing and supported by wood or metal posts.
2.7 rNTCDOT Class B stone for erosion control.
PART 3 - EXECUTION
3.1 CLEARING
A. Clearing and grubbing shall be scheduled and performed in such a manner that subsequent
grading operation and erosion control practices can follow immediately thereafter. Excavation,
borrow, and embankment operations will be conducted such that continuous operation. All
construction areas not otherwise protected shall be planted with permanent vegetative cover
within 21 calendar days after completion of active construction.
.1
3.2 STABILIZING
A. The angle for graded slopes and fills shall be no greater than the angle that can be retained by
vegetative cover or other adequate erosion control devices or structures. All disturbed areas not
to be paved and left exposed will, within 21 calendar days of completion of any phase of
grading, be planted or otherwise provided with either temporary or permanent ground cover,
devices, or structures sufficient to restrain erosion.
3.3 REGULATORY REQUIREMENTS
A. Whenever land disturbing activity is Undertaken on a tract, a ground cover sufficient to restrain
erosion must be planted or other wise provided within 21 calendar days on that portion of the
tract upon which further active construction is to being undertaken.
3. If any earthwork is to be suspended for -any reason whatsoever for longer than 21 calendar
days, the areas involved shall be seeded with vegetative cover or otherwise protected against
excessive erosion during the suspension period. Suspension of work in any area of operation
does not relieve the Contractor of the responsibility for the control of erosion in that area.

PART 4 - CONSTRUCTION PHASE
4.1 PRACTICES
A. Avoid dumping soil or sediment into any streambed or watercourse. Backfill for stream
crossings shall be placed dry and compacted to minimize siltation of the watercourse, where
applicable.
13. Maintain an undisturbed vegetative buffer where possible between a natural watercourse and
trenching and grading operations.
C. Avoid equipment crossings of streams, creeks, and ditches where practicable.
PART 5 - SEDIMENT CONTROL FEATURES
5.1 GENERAL
A. All devices (silt Fences, retention areas, etc.), for sediment control shall be constructed at the
locations indicated prior to beginning excavation on the site. All devices shall be properly
maintained in place until a structure or paving makes the device unnecessary or until directed
to permanently remove the device.
5.2 DESIGN APPLICATIONS
A. Mulch shall be used for temporary stabilization of areas subject to excessive erosion, and for
protection of seed beds after planting where required.
1. jute, mesh, etc. should be installed as per manufacturer's instructions.
13. Silt fences shall be used at the base of slopes and in drainage swales to restrict movement of
sediment from the site. Straw bales may be required for reinforcement.
C. Riprap shall be used at the proposed outfall pipes as indicated on plans.
D. Establish vegetative cover on all unpaved areas disturbed by the work.
J. Preparation of Seedbed. Areas to be seeded shall be scarified a depth of 6 inches until a
firm, well -pulverized, uniform seedbed is prepared. Lime, phosphorous, and fertilizer
shall be applied during the scarification process in accordance with the following rates.
a. Lime — 2 ton per acre
b. Nitrogen —100 pounds per acre
C. P:Os — 200 pounds per acre
2. Seeding. Disturbed areas along roads and ditches shall be permanently seeded with 10-
20 pounds per acre of centipede during the period from March through September.
Seeding performed during the period from April to August shall be temporarily seeded
with 40 pounds per acre of German Millet. The permanent vegetative cover will be over
seeded at the earliest possible time as specified above.
3. Mulch all areas immediately after seeding. Mulch shall be applied and anchored as
specified hereinbefore,

5.3 MAINTENANCE
A. The Contractor shall be responsible for maintaining all temporary and permanent erosion
control measures in functioning order. Temporary structures shall be maintained until such
time as vegetation is firmly established and grassed areas shall be maintained until completion
of the project. Areas which fail to show a suitable stand of grass or which are damaged by
erosion shall be immediately repaired.
5.4 REMOVAL OF SEDIMENT CONTROL DEVICES
A. Near completion of the project, when directed by the Owner's agent, the Contractor shall
dismantle and remove the temporary devices used for sediment control during construction.
All erosion control devices in seeded areas shall be left in place until the grass is established.
Seed areas around devices and mulch after removing or filling temporary control devices.
END OF SECTION 02410

Soil Map --Cumberland County, North Carolina
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34' 59 46"
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Feet
0 50 100 200 300
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iNIIIIIIIIIIIIII Conservation Service National Cooperative Soil Survey
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Soil Map—Cumbertand County, North Carolina
MAP LEGEND
MAP INFORMATION
Area of Interest (AOI)
fZ
Very Stony Spot
Map Scale: 1:1,460 if printed on A size (8.5" x 11") sheet.
0
Area of Interest (AOI)
wet Spot
The soil surveys that comprise your AOI were mapped at 1:24,000.
Solis
Soil Map Units
�
Other
Warning: Soil Map may not be valid at this scale.
Special
Point Features
Special
Line Features.4
Enlargement of maps beyond the scale of mapping can cause
Blowout
Gully
misunderstanding of the detail of mapping and accuracy of soil line
v
Short Steep Slope
placement. The maps do not show the small areas of contrasting
®
Borrow Pit
soils that could have been shown at a more detailed scale.
Omer
X
Clay Spot
Political Features
Please rely on the bar scale on each map sheet for accurate ma
Y p
♦
Closed Depression
0
Cities
measurements.
X
Gravel Pit
water Features
Source of Map: Natural Resources Conservation Service
Gravelly Spot
,- .
Streams and Canals
Web Soil Survey URL: http://websoilsurvey.nres.usda.gov
Coordinate System: UTM Zone 17N NAD83
®
Landfill
Transportation
,—,
This product is generated from the USDA-NRCS certified data as of
Lava Flow
Rails
the version date(s) listed below.
,k.
Marsh or swamp
interstate Highways
Soil Survey Area: Cumberland County, North Carolina
R
Mine or Quarry
US Routes
Survey Area Data: Version 11, Jul 3, 2012
p
Miscellaneous water
Major Roads
Date(s) aerial images were photographed: 6/21/2006
©
Perennial water
Local Roads
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
v
Rock Outcrop
imagery displayed on these maps. As a result, some minor shifting
t
Saline Spot
of map unit boundaries may be evident.
Sandy Spot
—
Severely Eroded Spot
0
Sinkhole
Slide or Slip
0
Sodic Spot
Spoil Area
Q
Stony Spot
USDA Natural Resources Web Soil Survey 7/30/2012
21111111111 Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map —Cumberland County, North Carolina
Map Unit Legend
Cumberland County, North Carolina (NC051)
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
Lbi3
Lakeland -Urban land complex, 1 to 8
percent slopes
1.2
23.5°%
WgB
Wagram-Urban land complex, 0 to 8
percent slopes
3.9
76.5°%
Totals for Area of Interest
5.2
100.0%
USDA Natural Resources Web Soil Survey 7/30/2012
2" Conservation Service National Cooperative Soil Survey Page 3 of 3

Depth to Water Table —Cumberland County, North Carolina
M
m
34° 59 59'
34" 59 43'
MopScale 1:1,450 d prated on A see (8 S' x 11") sheer.
N Meters
m A 0 10 20 40 60
N Feet
0 50 100 200 300
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
D7LLN W/.S� DyGSw o'.1GJ I V
1
8
3'
A
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34' 59 57"
n
ti
16 34" 59 47"
30
m
7/30/2012
Page 1 of 3

Depth to Water Table —Cumberland County, North Carolina
MAP LEGEND MAP INFORMATION
Area of Interest (ACI)
Map Scale: 1:1,460 if printed on A size (8.5" x 11") sheet.
Q
Area of Interest (A01)
The soil surveys that comprise your AOI were mapped at 1:24,000,
Solis
Soil Map units
Warning: Soil Map may not be valid at this scale.
Soil Ratings
Enlargement of maps beyond the scale of mapping can cause
0
0 - 25
misunderstanding of the detail of mapping and accuracy of soil tine
placement. The maps do not show the small areas of contrasting
0
25 - 50
soils that could have been shown at a more detailed scale.
Q
50 - 100
Please rely on the bar scale on each map sheet for accurate map
0
100 - 150
measurements.
150 - 200
Source of Map: Natural Resources Conservation Service
[]
> 200
Web Soil Survey URl_: http:l/websoilsurvey.nres.usda.gov
Coordinate System: UTM Zone 17N NAD83
Political Features
This product is generated from the USDA-NRCS certified data as of
p
Cities
the version date(s) listed below.
Water Features
Soil Survey Area: Cumberland County, North Carolina
1-
Streams and Canals
Survey Area Data: Version 11, Jul 3, 2012
Transportation
Date(s) aerial images were photographed: 6/21/2006
Rails
The orthophoto or other base map on which the soil lines were
.v
Interstate Highways
compiled and digitized probably differs from the background
iv
US Routes
imagery displayed on these maps. As a result, some minor shifting
of map unit boundaries may be evident.
Major Roads
Local Roads
USDA Natural Resources Web Soil Survey 7/30/2012
am Conservation Service National Cooperative Soil Survey Page 2 of 3

Depth to Water Table —Cumberland County, North Carolina
Depth to Water Table
Depth to Water Table— Summary by Map Unit— Cumberland County, North Carolina INC051j
Map unit symbol
Map unit name
Rating (centimeters)
Acres in AOI
Percent of AOI
LbB
Lakeland -Urban land
>200
1.2
23.5%
complex, 1 to 8 percent
slopes
WgB
Wagram-Urban land
192
3.9
76.5%
complex, 0 to 8 percent
slopes
Totals for Area of Interest
5.2
100.0%
Description
"Water table" refers to a saturated zone in the soil. It occurs during specified
months. Estimates of the upper limit are based mainly on observations of the water
table at selected sites and on evidence of a saturated zone, namely grayish colors
(redoximorphic features) in the soil. A saturated zone that lasts for less than a month
is not considered a water table.
This attribute is actually recorded as three separate values in the database. A low
value and a high value indicate the range of this attribute for the soil component. A
"representative" value indicates the expected value of this attribute for the
component. For this soil property, only the representative value is used.
Rating Options
Units of Measure: centimeters
Aggregation Method: Dominant Component
Component Percent Cutoff.' None Specified
Tie -break Rule: Lower
Interpret Nulls as Zero: No
Beginning Month: January
Ending Month. December
Natural Resources Web Soil Survey 7/30/2012
Conservation Service National Cooperative Soil Survey Page 3 of 3

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185 Airport Road, Fayetteville, NC
NC DENR Retention Requirements
Objective: design a wet detention basin with the following characteristics: a permanent water pool depth between 3- and
5-feet, a surface area that meets TSS removal requirements (values set by NC DENR and included here), a forebay that
is approximately 20 % of the total pond volume, a temporary water pool sired to detain the initial 1.0 inch of rainfall runoff, an
outlet device that drains the temporary water pool within 2-5 days, and a length -to -width ratio of approximately 3:1.
Step 1: Determine the surface area required for 90% TSS removal
Post -Development Conditions
Total Drainage Area 4.49 ACRE Value from CAD
Impervious Drainage Area 2.51 ACRE Value from CAD
Impervious Cover 55.9% Impervious Cover -(Impervious Drainage
Area)/(Total Drainage Area)*100%
Elevation of Permanent Pool Surface
190.50
FT
Value selected by designer
Average Depth of Permanent Pool
3.30
FT
Elevation of Wet Detention Pond Bottom
187.0
FT
Value from CAD
Approximate Pond Length
180
FT
Value from CAD
Approximate Pond Width
47
FT
Value from CAD
Len th:Width Ratio
4:1
Ratio=(Len th)1Width):1
Required SAIDA Ratio for 90% TSS Removal 3.450 Value from chart. Reference: "90% TSS
Removal
Required Permanent Pool Surface Area 61748 SF Required Surface Area=(Required SAIDA
Ratio) Drainage Area)
Provided Permanent Pool Surface Area 8,493 SF Interpolated value from stage -storage
calculations
Step 2: Determine the 1-inch runoff elevation within the wet detention pond.
Runoff Coefficient, Rv 0.553 INIIN Rv=0.05+0.009'(% impervious)
Required 1 A" Runoff Volume (Volume of 9.013 CF 1.0" Runoff Volume=l inch'Rv'1 foot/12
Temporary Pool) inch *(Total Drainage Area)
Total Volnrne to he Controlled 901.1 CF Total Volume to be Controlled=(Volume Below
Permanent_ _ Poo + fir_ 24hr. Runoff Volume)
Storage Elevation at Required Volume 191.44 FT Value is interpolation based upon stage -storage
values. See stage -storage calculations
Step 3: Calculate the required forebay volume (18-22% of total pond volume) and compare to the forebay volume provided._
Total Pond Volume 17.104 CF Value from stage -storage calculations
Required Forebay Volume 3,421 CF ForebaX Volume=(Total Pond Volume)*20%
Provided Forebay Volume 3,339 CF Value from stage -storage calculations
Provided Forebay Volume:Total Pond Volume 19.5% (Provided Forebay Volume)/(Total Pond
Volume)' 100 %
Sten 4: Verifv that time required to drawdown the 1.0-inch runoff volume is within 2 to 5 days
Diameter of Proposed Low -Flow Orifice
1,25
IN
Value chosen by designer
Riser Elevation of Outlet Structure
192.35
FT
Value chosen by designer
(Total Elevation Head Above Orifice)=(Riser
Total Elevation Head Above Orifice
1.85
FT
Elevation) -(Elevation of Permanent Pool
Surface)
(Average Elevation Head Above
Orifice)=((Storage Elevation at Required
Average Elevation Head Above Orifice
0.62
FT
Volume)+(Elevation of Permanent Pool
Surface)P3-(Storage Elevation at Required
Volume)
Cd, Coefficient of Discharge
0.60
Value chosen by designer
0, Flowrate Through Low -Flow Orifice
0.032-
CFS
Q=Cd"(Pi)"((Diameter of Orifice) *(I fV12
in 2/4' 2'32.2' Ave a Head) 12
Drawdown Time for 1.0"Runoff
3.24
DAYS
(Orawdown Time)=(1.0" Runoff Volume)/Q'(1
P:1ProjectslASlantic Brokerage112113.PE 185 Airport Road0ocumentslDesign CalculationslStormwaterlWel Pond

Lot 1, 185 Airport Road, Fayetteville, NC
Stage -Storage Calculations for Proposed Wet Detention Pond
determine the storage capacity and characteristics of the proposed wet detention pond.
Pond side slope above Permanent Pool 3
Veg. shelf 6" abovelbelow Perm. Pool 10 FT
Side Slope below planted shelf 3
incremental and cumulative storage of the wet detention pond per contour interval
Stage/Storage Above Permanent Pool (Including Forebay)
Cumulative
Contour
Incremental
Volume, S
Contour
Area (SF)
Volume (CF)
(CF)
190,50
8,493
0
0 --Permanent Pool
191,00
10,772
4.816
4,816
192.00
12,214
11,493
16,309
193.00
13,714
12,964
29,273
194.00
15,269
14.492
43,765
StagelStorage Total Pond
Cumulative
Contour
Incremental
Volume, S
Contour
Area (SF)
Volume (CF)
(CF)
187.00
2,676
0
0 ---Pond Bottom
188.00
3,786
3,231
3,231
189.00
5,039
4,413
7,644
190.00
6,424
5,732
13,375
190.50
8,493
3,729
17,104 ---Permanent Pool
191.00
10,772
4,816
21,921
191.44
11,386
4,875
26,795 Temporary Pool
192.00
12,214
11,493
33,414
193.00
13,714
12,964
46,378
194.00
15,269
14,492
60,869
Forebay Only (20% of Total Pond)
Cumulative
Contour
Incremental
Volume, S
Contour
Area (SF)
Volume (CF)
(CF)
187,00
571
0
0 -- Bottom Elev,
188.00
894
733
733
189.00
1,287
1,091
1,823
190.00
1,745
1,516
3,339 Forebay Volume
P:1ProjectslAtlantic Brokerage112113.PE 185 Airport Road0ocuments0esign CalculationslStormwaterMet Pond

Project Name: 185 Airport Road
Client: Atlantic Brokerage
Project Number: 12113.PE
Prepared By: GLM
Date: 8/3/12
Average Depth Calculation: (Option 2 per Errata)
*!Vote: Only used areas relative to the main pond
Pond #1
ABottom shelf =
4,679 sf
ABottom Pond =
2,105 sf
APerm Pool =
8,493 Sf
Depth =
4.0 ft
davq =
3.3 ft
PARAM_OUNTE
1= N C., I N f= 1= It 1 N r'.. I N C:

Project Name:
Client:
Lot 1A, 185 Airport Road - — — - --- .....
Atlantic Brokerage pARA M O UNT E
Project Number:
12113.PE
Prepared By:
GLM
Date:
7/30112
Basin: DA #1 [PRE] Drainage area= 4.49 acres = 0.007 mil
Area Calculations
Land Use Area Ac. % of Basin
Existing Impervious (Total) = 0.00 0.0%
Open Space - Fair 4.49 100.00/0
Sum: 4.49 10011/0

Project Name: Lot 1A, 185 Airport Road /�
Client: Atlantic Brokerage PARAMOUNTE
Project Number: 12113.PE N ti N
Prepared By: GLM
Date: 7/30/12
Basin. DA #1 [PRE] Drainage area= 4.49 acres = 0.007 miz
Curve Number
HSG:
A
B
C
D
Sum
0/6 of Basin
100.0
0.0
,'.0.0
0.0
100.0
Land Use
% of Basin
CN A
CN B
CN C
CND
Weighted CN
Open Space - Fair
100.0
49
59
79
84
49.00
Impervious
0.0
98
98
98
98
0.00
Sum: 100.0 Sum: 49.00
Curve numbers taken from: TR-55 Use: 49
= values input by user
= values calculated by spreadsheet

Project Name, Lot 1A. 155 Airport Road
Client: Atlantic Brokerage pp, R A M: OUN TE
Project Number: 12113.PE
Prepared By: GLM
Date: 7130/12
Basin: DA #1 [PRE] Drainage area= 4.49 acres = 0.007 miz
Time of Concentration
Overland Flow
Hydraulic Length =
667 ft.
Slope =
0.67
Ground Cover =
Short Grass
V (Figure 12.7) =
0.57 fps
T M
19.5 min.
T{ =
19.5 min. *Use 5 minutes min.

0
Project Name: Lot 1A. 185 Airport Road — -- ---- - - -- - ---
Ghent: Atlantic Brokerage p�:RA M o UNTE
Project Number: 12113.PE
Prepared By: GLM
Date: 7/30112
Basin: DA #1 [POST] Drainage area= 4.49 acres = 0.007 mi'
Area Calculations
Land Use
Area Ac.
% of Basin
Impervious (Total) =
2.51
55.9%
Open Space - Good
1.98
44.111/o
Sum:
4.49
100%

I
Project Name: Lot 1A, 185 Airport Road Client: Atlantic Brokerage PA RA M OUN TE
Project Number: 12113.PE ti z
Prepared By: GLM
Date: 7130/12
Basin: DA #1 [POST] Drainage area= 4,49 acres = 0.007 miz
Curve Number
HSG:
A
B
C
D
Sum
of Basin
100.0
0.0
0.0
0.0
100.0
Land Use % of Basin
CN A
CN B
CN C
CN D
Weighted CN
Impervious 55.9
98
98
98.-
98
54.78
Open Space - Good 44.1
39
51
74
80
17.20
Sum: 100.0
Sum: 71.98
Curve numbers taken from:
TR-55
Use: 72.00
= values input by user
= values calculated by spreadsheet

I
Project Name: Lot 1A, 185 Airport Road_.._._..........._.._..._....._..........._..----_._..._._.._.
Cher t. Atlantic Brokerage PA I RA_M0 UNTE
Project Number, 12113.PE
Prepared By: GLM
Date: 813112
Basin: DA #1 [POST] Drainage area= 4.49 -acres = 0.007 miz
Time of Concentration
Overland Flow
Hydraulic Length =
300 ft.
Slope =
1 0/0
Ground Cover =
Grass / Pav
V (Figure 12.7) =
2 fps
T =
2.5 min.
Tc = 5.0 min.
0

Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
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
0.047
1
888
1,265
----
------
------
Pre-dev
2
SCS Runoff
4.078
1
725
13,783
----
------
------
Post-dev
3
Reservoir
0.043
1
1444
5,095
2
191.63
12.089
Wet Pond
I
I
Wet Pond.gpw
Return Period: 1 Year
Monday, Jul 30, 2012

Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
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
(tuft)
Hydrograph
description
1
SCS Runoff
2.281
1
741
13,916
----
------
------
Pre-dev
2
SCS Runoff
14.17
1
725
43,794
----
------
------
Post-dev
3
Reservoir
2018
1
759
27,918
2
192.45
22,179
Wet Pond
Wet Pond.gpw
Return Period: 10 Year
Monday, Jul 30, 2012

Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
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
(cuft)
Hydrograph
description
1
SCS Runoff
4.361
1
737
23,050
------
------
Pre-dev
2
SCS Runoff
19.46
1
725
59,944
----
------
------
Post-dev
3
Reservoir
4.977
1
748
44,042
2
192.79
26,479
Wet Pond
Wet Pond.gpw
Return Period: 25 Year
Monday, Jul 30, 2012

Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
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
6.399
1
736
31,726
;
------
------
Pre-dev
2
SCS Runoff
23.97
1
725
73,912
----
•----•
------
Post-dev
3
Reservoir
10.69
1
736
57,992
2
192.95
28,594
Wet Pond
Wet Pond.gpw
Return Period: 50 Year
Monday, Jul 30, 2012

Hydrograph Summary Report Hydraflow Hydrographs by In,elisolve v9.22
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
8.730
1
735
41,624
----
------
------
Pre-dev
2
SCS Runoff
28.73
1
725
88,865
----
------
------
Post-dev
3
Reservoir
18.64
1
730
72,929
2
193.10
30.704
Wet Pond
Wet Pond.gpw
Return Period: 100 Year
Monday, Jul 30. 2012

0
'At
Dc — C', k a - -� q- c : f's
,jvre u: vnczzivp 1:zii:l .: :000�: rL:d rnioi;iwrl :;vli,,Xv:
4

tow""

Project Name: Lot 1A, 185 Airport road
Client: Atlantic Brokerage
Project Number: 12113.PE
Prepared By: GLM
Date: 7/30/2012
SEDIMENT BASIN CALCULATIONS
[Designed Per NCDENR Erosion Control Design Manual (6.61)]
Drainage Area (100 Ac. Max.) = 4.35 Ac.
QIo r. CaICS:
Impervious Area =
2.51 Ac.
Denuded Area =
1.84 Ac.
Impervious Area % of Basin =
57.70 %
Denuded Area % of Basin =
42.30 %
P A RA M OUNTE
Curve Number
HSG:
A
B
C
D
Sum
of Basin
100.0
0.0
0.0
0.0
100.0
Land Use % of Basin
CN A
CN B
CN C
CN D
Weighted CN
Impervious (Pavement/Roof Top) 56.1
98
98
98
98
55.00
Dirt 43.9
72
82
87
89
31.59
Sum: 100.0
Sum: 86.59
Curve numbers taken from:
TR-55
Use: 87
Tc *= 5.00 min.
- (Pipe Flow from Hydraflow Storm Sewer Analysis)
Q,O,,. (From Hydraflow) = 14.17 cfs

r
•
SEDIMENT BASIN CALCULATIONS
Requirements:
Min. Surface Area (435 sf/cfs) _
Min. Volume (1,800 cf/Ac.) =
Provided:
Basin Volume:
6,164 sf
7,830 cf
Contour
Contour Area
(SF)
Incremental
Volume (CF)
Cumulative
Volume
(CF)
187.00
2,676
0
0
188.00
3,786
3,231
3,231
189.00
5,039
4,413
7,644
190.00
6,424
5,732
13,375
190.50
8,493
3,729
17,104
191.00
10,772
4,816
21,921
192.00
12,214
11,493
33,414
192.35
12,719
4,363
37,777
192.75
13,320
5,208
42,985
193.00
13,714
3,379
46,364
194.00
15,269
14,492
60,855
Outlet Structure (See Hydraflow Data):
Riser EL. (Principal Spillway)= 192.35
Weir EL. (Emergency Spillway)= 192.75
Proposed Sediment Storage EL. = 191.00
Volume at Proposed EL. = 21,921 cf
Surface Area at Proposed EL. = 10,772 sf
Pond Dimensions: (@ Principal Spillway El.)
Length = 200 ft
Width = 71 ft
L to W Ratio = 3:1
pARA Mo uN TE
F. N .. - N r F_ R I - r- . . - r-
Skimmer Discharge Elevation
Riser Structure Elevation
Emergency Spillway Elevation
Skimmer Design: (SEE ATTACHED FAIRCLOTH SKIMMER SELECTION CHART)
*Outflow EL. = 190.50
* = Note that the calculated basin volume for dewatering is the difference in the volumes at
EL. 192.35 and EL. 190.50 and not from the bottom of the basin.
Drawdown Orifice Check
Dewater Vol. = 20,673 cf
Average Head = 0.62 ft
Ca = 0.6
D = 1.5 inches
Tpewater = 5 days

1
Determining the Skimmer Size
and the Required Orifice
for the
Faircloth Skimmer®S u rfa ce Drain
November 2007
Important note: The orifice, sizing chart in the Pennsylvania Erosion
Control Manual and reproduced in the North Carolina Design Manual
DOES NOT APPLY to our skimmers. It will give the wrong size orifice
and not specify which size skimmer'is required. Please use the
information below to choose the size skimmer required for the basin
volume provided and determine the orifice size required for the drawdown
time, typically 4-7 days in Pennsylvania and 3 days in North Carolina.
The size of a Faircloth Skimmer', for example a 4" skimmer, refers to the maximum diameter of
the skimmer inlet. The inlet on each of the 8 sizes offered can be reduced to adjust the flow rate
by cutting a hole or orifice in a plug using an adjustable cutter (both supplied).
Determining the skimmer size needed and the orifice for that skimmer required to drain the
sediment basin's volume in the required time involves two steps: First, determining the size
skimmer required based on the volume to be drained and the number of days to drain it; and
Second, calculate the orifice size to adjust the flow rate and "customize" the skimmer for the
basin's volume. The second step is not always necessary if the flow rate for the skimmer with
the inlet wide open equals or is close to the flow rate required for the basin volume and the
drawdown time.
Both the skimmer size and the required orifice radius for the skimmer should be shown for each
basin on the erosion and sediment control plan. Make it clear that the dimension is either the
radius or the diameter. It is also helpful to give the basin volume in case there are questions.
During the skimmer installation the required orifice can be cut in the plastic plug using the
supplied adjustable cutter and installed in the skimmer using the instructions provided.
The plan review and enforcement authority may require the calculations showing that the
skimmer used can drain the basin in the required time.
Determining the Skimmer Size
Step i. Below are approximate skimmer maximum flow capacities based on typical draw
down requirements, which can vary between States and jurisdictions and watersheds. If one 6"
skimmer does not provide enough capacity, multiple skimmers can be used to drain the basin.
For drawdown times not shown, multiply the 24-hour figure by the number of days required.
Example: A basin's volume is 29,600 cubic feet and it must be drained in 3 days. A 3" skimmer
with the inlet wide open will work perfectly. (Actually, the chart below gives 29,322 cubic feet but
this is well within the accuracy of the calculations and the basin's constructed volume.)
Example: A basin's volume is 39,000 cubic feet and it must be drained in 3 days. The 3"
skimmer is too small; a 4" skimmer has enough capacity but it is too large, so the inlet will need
November 6, 2007

s
to be reduced using step 2 to adjust the flow rate for the basin's volume. (It needs a 3.2"
diameter orifice.)
1 %" skimmer;
1,728
cubic feetin 24 hours
6,912
cubic feet in 4 days
with a 1'/2" head
3,456
cubic feet in 2 days
12,096
cubic feet in 7 days
5,184
cubic feet in 3 days
2" skimmer:
3,283
cubic feet'in 24 hours
13,132
cubic feet in 4 days
with a 2" head
6,566
cubic feet in 2 days
22,982
cubic feet in 7 days
9,849
cubic feet in 3 days
21/2" skimmer:
6,234
cubic feet in 24 hours
24,936
cubic feet in 4 days
with a 2.5" head
12,468
cubic feet in 2 days
43,638
cubic feet in 7 days
Revised 11-6-07
18,702
cubic feet in 3 days
3" skimmer:
9,774
cubic feet in 24 hours
39,096
cubic feet in 4 days
with a 3" head
19,547
cubic feet in 2 days
68,415
cubic feet in 7 days
29,322
cubic feet in 3 days
4" skimmer:
20,109
cubic feet in 24 hours
80,436
cubic feet in 4 days
with a 4" head
40,218
cubic feet in 2 days
140,763
cubic feet in 7 days
Revised 11-6-07
60,327
cubic feet in 3 days
5" skimmer:
32,832
cubic feet. in 24 hours
131,328
cubic feet in 4 days
with a 4" head
65,664
cubic feet in 2 days
229,824
cubic feet in 7 days
98,496
cubic feet in 3 days
6" skimmer:
51,840 cubic feet in 24 hours
207,360
cubic feet in 4 days
with a 5" head
103,680 cubic feet in 2 days
362,880
cubic feet in 7 days
155,520 cubic feet in 3 days
8" skimmer:
97,978 cubic feet in 24 hours
391,912
cubic feet in 4 days
with a 6" head
195,956 cubic feet in 2 days
685,846
cubic feet in 7 days
CUSTOM
293,934 cubic feet in 3 days
MADE BY ORDER
CALL!
Determining the Orifice
Step 2. To determine the orifice required to reduce the flow rate for the basin's volume and the
number of days to drain the basin, simply use the formula volume _ factor (from the chart
below) for the same size skimmer chosen in the first step and the same number of days. This
calculation will give the area of the required orifice. Then calculate the orifice radius using Area
= Tr rz and solving for r, r=1(Areal3.14) .The'supplied cutter can be adjusted to this radius to
cut the orifice in the plug. The instructions with the plug and cutter has a ruler divided into tenths
of inches. Again, this step is not always necessary as explained above.
An alternative method is to use the orifice equation with the head for a particular skimmer
shown on the previous page and determine the orifice needed to give the required flow for the
volume and draw down time. C = 0.59 is used in this chart.
Example: A 4" skimmer is the smallest skimmer that will drain 39,000 cubic feet in 3 days but a
4" inlet will drain the basin too fast (in 1.9 days) To determine the orifice required use the factor
of 4,803 from the chart below for a 4" skimmer and a drawdown time of 3 days. 39,000 cubic
{November 6. 2007 1 2

r
feet - 4,803 = 8.12 square inches of orifice required. Calculate the orifice radius using Area = n
r2 and solving for r, r = (8.1 2 / 3. i 4) and r = 1.61 ". As a practical matter 1.6" is about as close
as the cutter can be adjusted and the orifice cut..
Factors (in cubic feet of flow per square inch of opening through a round orifice with the head
for that skimmer and for the drawdown times shown) for determining the orifice radius for a
basin's volume to be drained. This quick method works because the orifice is centered and has
a constant head (given above in Step 1).
V/2" skimmer: 960 to drain in 24 hours 3,840 to drain in 4 days
1,920 to drain in-2 days 6,720 to drain in 7 days
2,880 to drain in 3 days
2" skimmer: 1,123 to drain in 24 hours 4,492 to drain in 4 days
2,246 to drain in 2 days 7,861 to drain in 7 days
3,369 to drain in-3,days
2%" skimmer: 1,270 to drain in 24 hours 5,080 to drain in 4 days
Revised 11-6-07 2,540 to drain in 2 days 8,890 to drain in 7 days
3,810 to drain in 3 days
3" skimmer: 1,382 to drain in 24 hours 5,528 to drain in 4 days
2,765 to drain in 2 days 9,677 to drain in 7 days
4,146 to drain in 3 days
4" skimmer: 1,601 to drain in 24 hours 6,404 to drain in 4 days
Revised 11-6-07 3,202 to drain in 2 days 11,207 to drain in 7 days
4,803 to drain in 3 days
5" skimmer: 1,642 to drain in 24 hours 6,568 to drain in 4 days
3,283 to drain in 2 days 11,491 to drain in 7 days
4,926 to drain in 3 days
6" skimmer: 1,814 to drain in 24 hours 7,256 to drain in 4 days
3,628 to drain in 2 days 12,701 to drain in 7 days
5,442 to drain in 3 days
8" skimmer: 1,987 to drain in 24 hours 7,948 to drain in 4 days
3,974 to drain in 2 days 13,909 to drain in 7 days
5,961 to drain in 3 days
J. W. Faircloth & Son, Inc.
Post Office Box 757
412-A Buttonwood Drive
Hillsborough, North Carolina 27278
Telephone [phone] FAX [phone]
FairclothSkimmer.com [e-mail]
Orifice sizing Revised 2-2-01, 3-3-05; 2-1-07: 11-6-07
November 6, 2007
3