20090430 Ver 1_Stormwater Info_20100416

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community infrastructure consultants
April 16, 2010
Ms. Annette Lucas
Division of Water Quality
401 Wetlands Unit
2321 Crabtree Blvd., Suite 250
Raleigh, NC 27604
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RE: Response to February 15, 2010 NCDWQ Comments on Johnston County Airport Runway
Safety Area and Corporate Area Development Stormwater Plan (DWQ Project #09-0430)
Dear Annette:
Attached to this letter is the revised stormwater design report that includes updated BMP plan
sheets in support of the 401 Water Quality Certification for the Johnston County Airport (No.
3822). This supporting information addresses DWQ comments received on February 15, 2010;
specifically related to the design of the proposed BMP grass swales. Included in the design report
are updated DWQ supplemental forms and checklists to support the design of the grass swales.
One of your comments concerned the establishment of freeboard for the BMP grass swales. The
BMP grass swales are located within a larger infield grass area that is approximately 330 feet wide.
The BMP grass swales occupy 19 to 89 feet of the infield depending on the peak flow, side slopes,
longitudinal slope, base width and Manning's roughness for each swale. Outside of the BMP grass
swales will be an additional grass buffer separating the BMP swales from the edge of the taxiway
or runway. The peak flows in the 10-year flood event will never reach the taxiways or runway and
will be contained to the grass swale BMPs. Our calculations include a formula that adds 0.5 feet
to the 10-year water surface and accounts for bottom width and side slope to determine the
easement width needed to achieve a freeboard of 0.5 feet. This is the reason all freeboards are
exactly 0.5 feet.
We have raised our weighted Rational C-factor values per one of your comments. The soil survey
for this area shows predominantly sandy soils surrounding the airport and our in-house soil
scientist findings showed that the soils are predominantly sandy in nature. However there are
pocket areas within our watershed that are not sandy so we have revised our calculations with a
more conservative C-factor value of 0.2.
We have provided a flow splitter for Swale #3 per your request; however a flow splitter for Swale
#5 was not added to the plans. The flows that enter Swale #5 enter as sheet flow for the entire
length of the swale. Flow is not concentrated at any one point and a flow splitter would not be
necessary or functional on this swale. The two proposed swales will collect the flow
independently and evenly.
The existing grass Swale 7meets all NCDWQ design requirements for a BMP grass swale. Similar
to the changes in Swale 6H, the first three drainage inlets in Swale 7 will be removed, the slope
drains will be plugged and a new inlet and 134 linear feet of closed 24-inch diameter RCP will be

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installed. By making these changes the travel length for runoff in Swale #7 will be increased and
more pollutant removal performed prior to outfalling off-site.
We have removed the proposed filter strips from the plans because of the questions raised about
conformity to NCDWQ design requirements. To offset the loss of water quality benefits from the
elimination of the filter strips the airport is proposing to remove several asphalt areas in the interior
areas of the airport. These asphalt areas will be replaced with managed turf grass. The asphalt
removal areas are taxiways and apron that are obsolete or will become obsolete with the
Corporate Area Development. These asphalt removal areas are clearly shown on the attached
plans. These areas total approximately 1.8 acres and will act as reduction of 1.8 acres of
impervious area from the Corporate Area Development.
I appreciate your input and patience on this challenging stormwater design. Please contact me or
David Kiker if you have any questions regarding this submittal. Thank you for your prompt
attention to this important aviation project.
Sincerely,
W.K. Dickson & Co., Inc.

Daniel P. Ingram
Project Manager
cc: Carroll Triplett, WK Dickson
Project file, 80324.00.CA
STORMWATER DESIGN REPORT
CORPORATE AREA
AT
JOHNSTON COUNTY AIRPORT
SMITHFIELD, NORTH CAROLINA
Prepared for
Johnston County Airport
80324.00.CA
Prepared by
F&WK
WDICKSON
community infrastructure consultants
720 Corporate Center Drive, Raleigh, NC
April 2010
•
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STORMWATER DESIGN REPORT
CORPORATE AREA
•
AT
JOHNSTON COUNTY AIRPORT
SMITHFIELD, NORTH CAROLINA
Prepared for
Johnston County Airport
80324.00.CA
Prepared by
community infrastructure consultants
720 Corporate Center Drive, Raleigh, NC
April 2010
0
•
•
•
Table of Contents
1. Introduction .................................................................................................................................1-1
1.1. Project Description ................................................................................................................1-2
1.2. Stormwater Design Requirements .........................................................................................1-3
2. Mapping ........................................................................................................................................2-1
2.1. USGS Map ............................................................................................................................2-1
2.2. Soil Survey Map .....................................................................................................................2-2
2.3. FEMA FIRM ..........................................................................................................................2-3
2.4. Aerial Photo ..........................................................................................................................2-4
3. Water Quality ..............................................................................................................................3-1
3.1. Pollutant Removal Credits .....................................................................................................3-2
3.2. Design of Retrofit BMP Swales ..............................................................................................3-2
3.3. Proposed Water Quality BMPs ..............................................................................................3-3
3.4. TSS Calculations ....................................................................................................................3-7
3.5. NCDWQ Supplemental and Certification Forms ...................................................................3-8
3.6. Nitrogen Calculations ............................................................................................................3-8
4. Water Quantity ............................................................................................................................4-1
4.1. Methodology .........................................................................................................................4-1
4.2. NRCS Curve Numbers ...........................................................................................................4-1
4.3. Time of Concentrations ........................................................................................................4-2
4.4. Drainage Basins .....................................................................................................................4-2
4.5. Proposed Dry Pond Improvements and Results .....................................................................4-2
5. Culvert Design ..............................................................................................................................5-1
5.1. Hydrology .............................................................................................................................5-1
5.2. Hydraulic Modeling ...............................................................................................................5-1
5.3. Outlet Protection at Culvert ..................................................................................................5-2
Tables
Table 1: Pollutant Loading Summary .................................................................................
Table 2: Summary of Existing Conditions Grass Swale BMP Design Performance ..............
Table 3: Summary of Existing Conditions Grass Swale BMP Design Performance ..............
Table 4: Proposed Landuse at Corporate Area Development Project ..................................
Table 5: TSS Removal Summary .........................................................................................
Table 6: Summary of Nitrogen Export Loading Rates at Proposed Corporate Hangar Area.
Table 7: Nitrogen Removal Summary .................................................................................
Table 8: Hydrologic Input Data ..........................................................................................
Table 9: Peak Flow Summary at Dry Pond .........................................................................
Table 10: Peak Flow Summary at Proposed Culverts ..........................................................
Table 11: HEC-RAS Results at Swift Creek Road .................................................................
Table 12: HEC-RAS Results at Runway Safety Area for Triple 10-ft by 7-ft Culverts ............
............1-1
............3-5
............3-5
............3-7
............3-8
............3-9
............3-9
............4-2
............4-3
............5-1
............5-2
............5-2
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Appendices
• Appendix A - Overview Map
Appendix B - Soils Data
Appendix C - FEMA Firmette
Appendix D - BMP Overview Map
Appendix E - Photo Log
Appendix F - Grass Swale Performance, Manning's "n' Calculations & Nomograph, Flow
Splitter Calculation and TSS and Nitrogen Loadings Spreadsheet
Appendix G - DWQ Supplemental Forms and Checklists
Appendix H - Pre/Post Calculations for Water Quantity Analysis
Appendix I - Hydraflow Model Results
Appendix J - HEC-RAS Output
Appendix K - Riffle Grade Control Outlet Protection Calculation
•
•
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 1.0
• Introduction
This report supports the design of the best management practices (BMPs) that are needed to bring the
Johnston County Airport into compliance with Johnston County and the State of North Carolina
Department of Water Quality (NCDWQ) regulatory requirements for new development. As shown in
Appendix A, the airport is proposing two on-site projects as part of this development. The first project
will increase the length of the northern-most existing runway safety area, and the second project
involves the construction of new hangars within the corporate area of the airport. This second project is
referred to in this report as the Corporate Area Development project. The separately attached set of
design plans show the proposed projects and the BMPs needed to meet the regulatory requirements for
water quality and quantity. This report also supports a land disturbance permit from the Land Quality
Section of North Carolina Department of Environment and Natural Resources (NCDENR) - Division of
Land Resources for the design of the erosion control measures shown in the separately attached plans.
The Johnston County Airport is located in the Neuse River Basin, which is a nutrient-sensitive watershed
subject to regulatory requirements for nutrient export. Because of the new impervious areas proposed
as part of the Corporate Area Development project, the County limits nitrogen export from the site to a
rate of 8.0 Ibs/ac/year in order to participate in the "buy-down" program. As shown in Table 1 and
described in more detail later in the report, the proposed project exceeds minimum requirements for
nitrogen removal in order to participate in the buy-down program. The airport is classified as industrial
landuse, and new development must meet National Pollution Discharge Elimination System (NPDES)
• Phase 1 stormwater requirements. As enforced by NCDWQ, one of these NPDES requirements is to
reduce total suspended solids (TSS) for new development by 85 percent by implementing BMPs. The
following two tables show that the project exceeds NCDWQ regulatory requirements for TSS (85
percent reduction) and nitrogen export (8.0 Ib/ac/yr):
Tablel: TSS Pollutant Loading Summary
•
TSS Export Pollutant Load Pollutant Load Pollutant Load Total Pollutant % TSS
Load Without Required for Removed by Removed by Load Removed Reduction with
BMPs in Place Removal to Grass Swales Proposed 0b) BMPs in Place
(I b) Achieve 85% (1 b) Asphalt
TSS Reduction Removal (Ib)
(I b)
6827 5803 4967 851 5818 85.2%
Table2: Nitrogen Pollutant Loading Summary
Nitrogen Export Pollutant Pollutant Load Pollutant Load Total Pollutant Export Loading
Loading Rate Removal Load Removed by Removed by Load Removed Rate w/ BMPs
Without BMPs Required to Grass Swales Proposed (lb) in Place
in Place (Ib) Enter Buy- (lb) Asphalt
Down Program Removal (Ib)
(8 I b/ac/yr)
0 b)
289.4 139.8 133.1 35.9 168.9 6.41b/ac/yr
iunnmun k-uunty Hirport mormwater uesign
Corporate Area Development and Extended Runway Safety Area Projects 1-1
WK Dickson & Co., Inc.
Section 1.0
• Introduction
In addition, the proposed project must not increase the post project 1-year peak flow above the pre-
project conditions of 143 cfs. As detailed later in the report the project meets this requirement by
reducing the proposed conditions peak flow to 107 cfs. The County requirement for reducing the post
project 1-year peak flow to at or below the pre-project conditions will be met by constructing a dry
pond located downstream of the existing runway (see Appendix A). As shown in this report the
proposed on-site improvements will bring the project into compliance with NCDWQ, Johnston County
and NCDENR requirements for stormwater and erosion control.
1.1 Project Description
The Corporate Area Development and Extended Runway Safety Area project are two independent
project areas that drain to two different sub-watersheds. As shown in Appendix A, the Corporate Area
Development Project is located adjacent to the main terminal area, and the Extended Runway Safety
Area Project is located at the northern side of the existing runway. Approximately 14.6 acres of new
impervious areas are proposed with the Corporate Area Development project and no new impervious
areas are proposed for the Extended Runway Safety Area project. A further description of the project
follows:
Corporate Area Development Project: This is a multi-phased project that will result in a predominantly
impervious site made up of a large, concrete apron with hangars to house airplanes. The following is a
• more detailed description of the two phases that will make up this project:
• Phase 1 - As shown on Sheet C-8 and C-9 of the plans, initial clearing and grading will occur in
Phase 1 of the project. This will include four open, grass-lined swales that collect stormwater
and direct runoff to a series of temporary sediment traps that will control erosion. No new
impervious areas are proposed as part of this phase of the project.
• Phase 2 - The second phase of the project will include final grading and installation of the apron
and hangars. This phase of the project will include a closed drainage system that collects
stormwater runoff, an off-site dry pond that attenuates peak flows, and a series of off-site grass
swales that treat water quality. Because of the relatively high groundwater elevations near the
Corporate Area Development area, constructing a dry pond or bioretention pond became
difficult without raising the site by approximately 5 feet. For this reason, an off-site dry
detention pond, an off-site series of BMP grass swales, and an off-site replacement of existing
asphalt areas with grass have been proposed to meet water quality treatment requirements.
Extended Runway Safety Area: The existing grass safety area north of the runway will be extended
approximately 700 linear feet over Reedy Creek. This project will include installing 620 linear feet of
triple 10-feet by 7-feet reinforced concrete box culverts (RCBCs) at Reedy Creek. A more detailed
description of the proposed culvert design is provided later in this report. This reach of Reedy Creek is
not a FEMA-identified stream, and, therefore, a submittal to FEMA will not be required.
is
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects 1-2
WK Dickson & Co., Inc.
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Figure 1: Location Map
Section 1.0
Introduction

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1.2 Stormwater Design Requirements
The Johnston County Airport is located in the Neuse River Basin, and is subject to both state and local
regulatory stormwater requirements. The proposed project will be subject to following water quality
and quantity requirements:
• TSS: Because the airport has an industrial landuse classification, the proposed project will need to
remove 85 percent TSS to meet NCDWQ NPDES Phase 1 stormwater requirements.
• Total Nitrogen, N: The Johnston County airport is located in the Neuse River Basin, which is
classified as Nutrient Sensitive Waters (NSW). The overall Neuse NSW Strategy, calls for each
major source to reduce its nitrogen pollution by 30 percent. Although this is a state
requirement, the program is administered by Johnston County. The project will be required to
reduce nitrogen loadings to 8.0 Ibs/ac/year to qualify for the buy-down program, or reduce
nitrogen loadings to 3.6 lb/ac/year to meet Johnston County requirements for water quality. If a
loading rate of 3.6 lb/ac/year is not achieved through the use of BMPs, the airport may elect to
pay into a mitigation bank to offset the impacts of the project.
• Attenuation for 1-Year, 24-hour Storm: Reduce post-project peak flows for the 1-year frequency
24-hour duration storm to at or below the pre-project peak flow. This is a Johnston County
water quantity requirement for the protection of stream channels.
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects 1-3
WK Dickson & Co., Inc.

Section 1.0
Introduction
• Attenuation for the 10- and 25-Year, 24-hour Storms: Reduce post-project peak flows for the 10-
and 25-year frequency 24-hour duration storms so there is less than a 10 percent increase to
pre-project conditions flows. Detention or a waiver will be required from the Johnston County
stormwater administrator if peak flows exceed pre-project flows by more than 10 percent. This
is a Johnston County requirement for water quantity.
•
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L
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects 1-4
WK Dickson & Co., Inc.
Section 2.0
• Mapping
This section shows some of the available mapping of the site, including a USGS map, an NRCS soil
map, a FEMA Flood Insurance Rate Map (FIRM), and an aerial photograph showing existing conditions
landuse.
2.1 USGS Map:
The discharge flows into Reedy Branch, then in a westerly direction to Swift Creek. The project
coordinates are 35°32'27"N, 78°23'31"W.
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Figure 2: USGS Topographic Quadrangle (Saluda South)

Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
2-1
Section 2.0
• Mapping
2.2 Soil Survey Map
The soils found on the site have a NRCS hydrologic soil group of B (well draining) to D (poorly
draining). The following map shows the distribution of the soils over the project area. See Appendix B
for more detailed soil descriptions.

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Figure 3: NRCS Hydrologic Soil Groups
•
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects 2-2
WK Dickson & Co., Inc.
•
Section 2.0
Mapping
2.3 FEMA FIRM
Figure 4 shows the FEMA Flood Insurance Rate Map (FIRM) panel 3720168500J dated December 5,
2005, which includes the effective 100-year floodplains near the Johnston County Airport. A firmette is
provided in Appendix C. As shown in Figure 4, the project is not on a FEMA-identified stream;
therefore, a Conditional Letter of Map Revision will not be required as part of this project.

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Figure 4: FEMA Flood Insurance Rate Map
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
2-3
Section 2.0
Mapping
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2.4 Aerial Photo
The exhibit below shows the location of the airport on an aerial photo, courtesy of Google Earth. The
project coordinates are 35°32'27"N, 78°23'31 "W.
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Figure 5: Existing Conditions Land Use
•
Johnston County Airport Stormwater Design
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
2-4
Section 3.0
• Water Quality
With the construction of 14.6 acres of new impervious area, the Corporate Area Development project
will be subject to reducing both TSS and nitrogen with a series of BMPs. This section of the report
documents the design of those BMPs, and shows that both Johnston County and NCDWQ requirements
are being met for nitrogen and TSS export. Because the Extended Runway Safety Area does not involve
the installation of impervious areas, there are no TSS or nitrogen removal requirements for this project.
No specific water quality BMPs are proposed as part of Extended Runway Safety Area project.
The Corporate Area Development project will include installation of 14.6 acres of new impervious
areas; therefore, BMPs will be needed to address water quality requirements for both Johnston County
and NCDWQ. Appendix D shows an overview map of the BMPs proposed for this project. Installing
on-site BMPs became problematic because of the proximity of the seasonal high water table near the
proposed Corporate Area Development project. Therefore, the design approach for addressing
regulatory requirements for water quality is to perform treatment "off-site".
Studies have shown that
standing bodies of water
such as wet ponds or
extended detention
wetlands improve the
• waterfowl habitat.
Reducing the potential for a
bird strike is directly related
to limiting standing water
on or adjacent to an
airport. Grass swales are
ideal airport BMPs because
they minimize the time that
water ponds following a
storm, and limits potential
for bird strikes. For these
reasons, the water quality
requirements for the I Photo 1: Grass Buffers at Taxiway
Corporate Area
Development project will be met by retrofitting BMPs in off-site, existing, grass swales that currently
collect and filter runoff from impervious taxiway and runway impervious areas prior to entering the
downstream open drainage systems. The existing, flat, wide infield grass areas and swales are ideal for
water quality treatment, and will require few improvements to meet NCDWQ design requirements for a
BMP grass swale.
•
Johnston County Airport Stormwater Design Project Page 3-1
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
• Water Quality
Swales #3 and #5 are not meeting existing NCDWQ design requirements for a BMP grass swale as
outlined in the NCDWQ Best Management Practices Manual dated July 2007 (see Appendix E), and
will be retrofit with the following improvements:
• Flatten side slopes to 25(H):1(V).
• Flatten bottom slopes to 0.0054 feet/feet.
• A concrete flow splitter and level spreader will be added to Swale #3 to create twin grass swales,
and effectively reduce the peak flow in half. Swale #5 does not require a flow splitter because
flow is not concentrated from an upstream drainage system.
Swale #7 currently has several drainage inlets that direct flow into a series of slope drains that outfall
into an open ditch and eventually into Swift Creek. The length of swale between inlets is relatively
short and does not optimize the potential for water quality treatment prior to outfalling into the
downstream open swale. The airport is proposing to eliminate three of the inlets and outfall at the
northeastern most side of the infield. The downstream inlet and 12-inch diameter closed drainage pipe
will be replaced with a larger drainage inlet and a 24- inch diameter reinforced concrete pipe (RCP). By
making these changes, the travel length for runoff in Swale #7 will be increased, and more pollutant
removal performed prior to outfalling off-site.
is In addition to the grass swale improvements, the airport is proposing to remove an area of asphalt in
Basins #1 and #5 that are no longer being used by the airport. The 1.79 acres of impervious area will
be replaced with grass. The replacement of asphalt with grass will result in the removal of 35.86 Ibs of
Nitrogen, and 850 Ibs of TSS per year.
Where the grass swales are meeting current design standards, the airport will secure permanent
drainage easements to ensure that the swales will be in place to treat water quality in the future. In
several cases the swales do not meet NCDWQ design requirements and will require retrofit
improvements. As shown in this report, the treatment of these "off-site" areas will exceed the minimum
Nitrogen and TSS reduction requirements for the Corporate Area Development project.
3.1 Pollutant Removal Credits
The following pollutant removal credits were assumed in the design of the BMPs shown in this report
and separately attached plans. This information was taken directly out of the 2007 NCDWQ BMP
manual for a grass swale:
• Grass Swales: 35 percent for pollutant removal credit TSS
• Grass Swales: 20 percent for pollutant removal credit Nitrogen
The majority of the BMPs proposed for water quality treatment are in series. The runoff from the upper
grass swales will be retreated by downstream grass swales. For the purposes of quantifying pollutant
•
Johnston County Airport Stormwater Design Project Page 3-2
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
• Water Quality
removal benefits, it was assumed that a maximum of two BMPs were in series. This is consistent with
guidelines found in NCDWQ design manual.
3.2 Design of Retrofit BMP Swales
The following criteria were used in the design of the BMPs shown in this report and separately attached
plans. The BMPs consist of securing recorded drainage easements around existing grass swales that are
already in compliance with DWQ design requirements, and making retrofit improvements to those
swales that do not meet minimum design requirements. The evaluation of whether BMPs meet DWQ
minimum design requirements is based on the following information taken directly out of the Major
Design Elements of the 2007 NCDWQ BMP manual:
Grass Swales:
• BMPs will be recorded in a drainage easement.
• Peak runoff for a 10-year storm shall not erode swale.
• Swales shall convey the 10-year design discharge while maintaining a 0.5-foot freeboard
and without exceeding the maximum permissible velocity. The maximum velocity shall be
1 foot/second for the 10-year, 24-hour storm.
• Side slopes shall be no steeper than 5:1.
• A maintenance agreement is provided.
• Swale lengths are a minimum of 150 feet.
• Swales shall have a 1-foot minimum distance from the bottom of the swale to the seasonal
high water table (SHWT).
• Maximum longitudinal slope of 5 percent.
3.3 Proposed Water Quality BMPs
The following is a description of each of the
BMPs shown in Appendix D that bring the
project into compliance for water quality.
Table 1 summarizes the design performance of
the following BMPs:
• Grass Swales #1A and 1B: The existing
grass swale meets all NCDWQ design
requirements for a BMP grass swale.
No modifications to the existing
conditions swale geometry or slope are
proposed as part of this BMP.

Grass Swale #2: The existing grass Swale I Photo 2: Grass Swale #1 and E
meets all NCDWQ design requirements for a BMP grass swale.

existing conditions swale geometry or slope are proposed as part of this BMP.
Johnston County Airport Stormwater Design Project Page 3-3
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
No modifications to the
Section 3.0
Water Quality
• Grass Swale #3: The existing grass swale does not meet minimum NCDWQ design requirements
for velocity or flow depth. The upstream culvert will be extended and a concrete flow splitter
retrofit to split flows evenly into proposed twin grass BMP swales. Removing a portion of the
sub-basin's asphalt area reduces flows, but does not reduce flow enough to bring the swale into
regulatory compliance for a BMP grass swale. For this reason, the existing swale geometry will
be modified to reflect twin chambered grass swales, each with a bottom width of 3 feet and side
slopes of 25:1. Splitting flows effectively reduces the peak flow in the swale from 37.3 cfs to
18.7 cfs. These changes will reduce both the 10-year velocity below 1.0 feet/second and the
10-year maximum depth below 1.0 foot.
• Grass Swale #4A and 4B: The existing grass swale meets all NCDWQ design requirements for a
BMP grass swale. No modifications to the existing conditions swale geometry or slope are
proposed as part of this BMP.
• Grass Swale #5: The existing grass swale does not meet minimum NCDWQ design requirements
for velocity or flow depth. Removing a portion of the sub-basin's asphalt area reduces flows but
does not reduce flow enough to bring the swale into regulatory compliance for a BMP grass
swale. For this reason, the existing swale geometry will be modified to reflect a twin chambered
grass swales each with a bottom width of 3 feet and side slopes of 10:1. This effectively
reduces the flow in the swale from 33.0 cfs to 16.5 cfs. These changes will reduce both the
10-year velocity below 1.0 feet/second and 10-year maximum depth below 1.0 foot.
• Grass Swales #6A through #6G, #61 and #6J: The existing grass swale meets all NCDWQ design
requirements for a BMP grass swale. No modifications to the existing conditions swale
geometry or slope are proposed as part of this BMP.
• Grass Swale #6H: The existing grass swale meets all NCDWQ design requirements for a BMP
grass swale. The existing swale is drained by two inlets - one located at the swale's
approximate midpoint, and the other located at the swale's terminal end. The midpoint inlet
will be plugged and abandoned so that flows in this swale travel a longer distance prior to
outfalling into the downstream drainage system.
• Grass Swale #7: The existing grass swale meets all NCDWQ design requirements for a BMP grass
Swale. Similar to the changes in Swale 6H, the first three drainage inlets in swale 7 will be
removed, the slope drains will be plugged and a new inlet and 134 linear feet of closed 24-inch
diameter RCP will be installed. By making these changes the travel length for runoff in Swale
#7 will be increased and more pollutant removal performed prior to outfalling off-site.
•
Johnston County Airport Stormwater Design Project Page 3-4
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
•
0
Section 3.0
Water Quality
• The following table summarizes the performance of the existing BMP grass swales being used for
water quality treatment:
Table 2: Summary of Existing Conditions Grass Swale BMP Design Performance
Swale
No. 10-Year
Peak
Flow
(cfs) 10-Year
Flow Depth
(ft) 10-Year
Velocity
(ft/sec) Length
(ft) Side
Slopes
(ft/ft) Clearance to
SHWT
(in) Freeboard
(ft)
1A 4.28 0.49 0.58 380 23 >60 0.5
1 B 3.17 0.36 0.52 240 35 >60 0.5
2 14.05 0.83 0.59 730 31 >60 0.5
3 37.31 1.37 2.00 600 7 >46 0.5
4A 3.87 0.63 0.84 491 7 26 0.5
4B 11.10 0.85 0.66 491 20 26 0.5
5 33.01 1.47 2.03 1231 5 17 0.5
6A 6.77 0.79 0.62 718 15 >38 0.5
6B 3.49 0.62 0.54 300 14 >38 0.5
6C 12.06 0.88 0.92 1404 15 >27 0.5
6D 3.46 0.73 0.37 300 15 38 0.5
6E 4.05 0.70 0.56 349 12 >38 0.5
6F 3.46 0.62 0.52 300 14 >38 0.5
6G 2.90 0.60 0.42 251 16 >38 0.5
6H 5.76 0.65 0.71 498 16 >38 0.5
61 11.85 0.94 0.75 1022 16 45 0.5
6J 10.64 0.93 0.68 937 16 45 0.5
7 18.71 0.82 0.89 900 28 23 0.5
INULe: -)nvv i- ,)easonai nign water taDie. tsoia indicates that minimum design requirements for a grass
swale BMP were not met.
Appendix F includes a detailed summary of the hydraulic performance of the existing and proposed
grass swales. An in-house spreadsheet (Appendix F) was developed to evaluate the hydraulic
performance of the existing grass swales. This spreadsheet is based on flows calculated using the
Rational Method and velocities and depths calculated using Dodson's computer software program
Hydrocalc Hydraulics. Manning's "n" values found in this spreadsheet were developed using the
USACE Report EM 1110-2-1601 for grass lined channels. Rational C-factors were developed by
weighting the percentage of grass coverage versus the percentage of asphalt coverage and applying the
appropriate coefficients for runoff C-factors. Soils at the site are predominantly a loamy-sand and the
grass coverage is excellent. Table 3.2 of the NCDWQ BMP Manual shows a C-factor of 0.1 for grass
with sandy soils and slopes less than 2 percent. At the direction of DWQ, a value of 0.2 for grass has
been used to develop the peak flows for the evaluation of BMP performance. This value is
conservative, and generated peak flows that were approximately 20 percent higher than those assuming
the lower C-factor for grass. Time of concentrations were assumed to be five minutes for the majority of
the basins, with the exception of basins in series. In those basins found in series, the time of
•
Johnston County Airport Stormwater Design Project Page 3-5
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
Water Quality
concentration was assumed to be the five minutes from the previous basin plus the time of travel
through the downstream basin. The downstream travel time was assumed to be the distance traveled
divided by the maximum velocity allowed in a grass swale BMP (1 foot/second). This assumption is
conservative and will generate a larger peak flow for the purposes of evaluating the performance of the
BMP grass swales. The shape of basin #6C does not allow for an accurate estimate of a peak flow using
the Rational method with its artificially high time of concentration. For this reason, the time of
concentration for Swale #6C was capped at 15 minutes to provide a more accurate (and more
conservative) estimate of the peak flow for this basin.
Figure 5 shows the nomograph used to develop Manning's "n" values for varying depths. Per the
direction of DWQ, values using the "D" grass type were taken off Figure 1 and the "n" value capped at
0.10. Grass types for a "D" grass type include Bermuda grass, common lespedeza and other grass-
legume mixtures which are prevalent at the airport. As shown in the hydraulic performance
spreadsheet the requirement for maintaining a 10-year swale velocity less than 1.0 feet per second or a
flow depth of less than 1.0 foot has not been achieved in swales #3 and #5. For these two swales, the
channel slopes were reduced, the bottom width adjusted, or the side slopes reduced in order to bring
the swale into compliance with DWQ design requirements. Appendix F shows that the proposed
swales have 10-year velocities less than 1.0 foot/second and depths less than 1.0 feet.
as
0.4
0.3
0.2
U'1
al
0.00
3
a0s
a04
0.02
01
VR
Figure 5 - "N" Value Relationships for Grass
A licensed soil scientist from WK Dickson collected seasonal high water table information for the
swales on November 3, 2009. Borings were taken with a hand auger to a depth of 60 inches at the
existing swale locations, as shown in Appendix D. Table 2 includes a summary of the depths of the
Johnston County Airport Stormwater Design Project Page 3-6
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
0.2 0.4 0.i 0.2 1 2 4 f • 10 20
•

Section 3.0
Water Quality
seasonal high water table for each of the swales proposed to be used as a BMP. As shown in Table 2,
with the exception of grass swales #3 and #5, the existing grass swales meet all of the major NCDWQ
design elements.
Johnston County Airport Stormwater Design Project Page 3-7
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
• Water Quality
3.4 TSS Calculations
For the purposes of showing that the project meets NCDWQ design requirements for TSS, an existing
loading rate for the Corporate Area Development site was calculated based on the overall site drainage
area and percent impervious. The proposed Corporate Area Development project annual loading rate is
based on the landuse shown in the following table:
Table 3: Proposed Landuse at Corporate Area Development Project
Landuse Classification Area (acres)
Buildings 3.0
Grass 4.1
Pavement 11.6
Woods 0.0
I otal Drainage Area = 18.7 acres
The weighted percent impervious for the site is approximately 78 percent. Because grass swales have
relatively low efficiency rates for the removal of TSS and nitrogen, a larger off-site area of
imperviousness will need to be treated to offset the lack of on-site treatment for Corporate Area
Development area. As shown in Appendix D, the existing runways and taxiways were targeted as the
ideal locations to establish the off-site BMPs needed to meet regulatory requirements. Individual
• drainage areas and percent impervious for each of the grass swales were calculated in GIS and directly
input into the in-house spreadsheet shown in Appendix F. Loading rates of the grass swales were
calculated based on the Schueler Simple Method, as described for the proposed conditions Corporate
Area Development area. TSS removal amounts were calculated based on a 35 percent removal rate.
There are numerous grass swales located throughout the airport property. For the purposes of satisfying
nutrient removal requirements for the proposed project, seven swales were identified and calculations
were performed on these swales. The grass swale BMPs range from 260 feet to over 5000 feet in
length. Each of the six major grass swales was divided into smaller segments for the purposes of
calculating nutrient removal loadings (see Appendix F). A length of 150 feet was assumed for the
minimum length of a grass swale BMP. It was assumed that retreatment could only occur once. In
other words, the TSS load that bypasses the first 150-feet long segment of Swale #3 can only be
retreated at the next adjacent 150-feet long segment of Swale #3.
An in-house spreadsheet was developed (see Appendix F) that shows the proposed annual loading for
the Corporate Area Development area to be 6827 lbs. The proposed BMPs are required to remove 85
percent of this loading which totals 5803 lbs. This loading for TSS was calculated using the Schueler
Simple Method along with an assumed correction factor of 0.90, an annual rainfall amount of 47.4
inches, and a 54.5 mg/I flow-weighted mean concentration for TSS in an urban watershed.
L = [(P)(P, )(R„Y (C)(A)(2.72
Schueler Simple Method Equation: )
•
Johnston County Airport Stormwater Design Project Page 3-8
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
• Water Quality
As shown in the TSS calculation spreadsheet (Appendix F), the proposed conditions loading at the
corporate area hangars is 6827 Ibs of TSS. The required load needed to achieve 85 percent TSS
reduction is 5803 lbs. Table 4 and Appendix F show that the proposed BMPs remove 4967 Ibs of TSS,
which results in a net reduction of 75.1 percent.
Table 4: TSS Removal Summary
Grass Swale ID Cumulative
Drainage Area
(ac) TSS Load Supplied
(lb) TSS Load
Removed ON Weighted Percent
of Removal
GS #1 2.98 345 143 41.4
GS #2 4.90 724 377 52.1
GS #3 15.43 1326 643 48.5
GS #4 5.76 717 360 50.2
GS #5 12.70 1581 868 54.9
GS #6 21.81 4095 1907 46.6
GS #7 9.53 1240 669 54.0
Total I 4967
For this reason an additional load reduction of 836 Ibs was needed to achieve the 85 percent reduction.
This reduction was achieved by removing 0.52 acres (22,586 sq ft) of existing asphalt found at the
runway turnaround area located in Basin #5 and several areas located near the Basin #1 taxiway area
(55,511 sq ft). The annual net reduction to the TSS load by the removal of asphalt and replacement
with grass is 850 lbs. When combined with the annual removal load for the existing swales the total
annual load removed is 5818 lb. This load exceeds the minimum needed and results in a net reduction
of 85.2 percent.
3.5 NCDWQ Supplemental, Certification Forms and Operation & Maintenance Apareement
Included with this are the completed NCDWQ supplemental and certification forms for a grass swale
report (see Appendix G). As shown in this report and the complete supplemental and certification
forms, the proposed BMPs meet current DWQ design standards. An operation and maintenance
agreement for the swales is provided in Appendix G.
3.6 Nitrogen Calculations
Loadings for Nitrogen were calculated using the NCDWQ approved loading rates of 21.2 lb/ac/year for
impervious surfaces and 1.2 lb/ac/year for open spaces. Using the landuse shown in Table 2, the
proposed Corporate Area Development project results in a pre-BMP nitrogen export rate of 16.9
Ibs/acre/year. BMPs are required to reduce nitrogen to 8.0 Ibs/acre/year or lower. The threshold export
rate of 8.0 Ibs/acre/year is required because the airport is located in one of the County's sensitive
watersheds. A series of grass swales will exceed the minimum nitrogen removal threshold, and qualify
the airport to participate in the mitigation buy-down program. The following table summarizes the
C:
Johnston County Airport Stormwater Design Project Page 3-9
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 3.0
. Water Quality
nitrogen removal loading needed to enter the buy-down program, and to reach the ultimate goal of a
3.6 Ibs/ac/year loading rate:
Table 5: Summary of Nitrogen Export Loading Rates at Proposed Corporate Hangar Area
Condition Nitrogen Export Loading Rate Nitrogen Export Loading Rate
(Ibs/year) (Ibs/ac/year)
Proposed Landuse with No BMPs in 315.3 (see Appendix F) 16.9
Place
Removal Load Needed to Reach 139.8 8.0
Threshold of 8.0 Ibs/ac/year
Removal Load Needed to Reach 222 3.6
Threshold of 3.6 Ibs/ac/year
Removal Load Achieved with Off-site 133.1 8.3
Proposed BMPs in Place
Removal Load Achieved with Off-site 35.9 NA
Asphalt Removal
Total Removal Achieved 168.9 6.4
The proposed plan to address nitrogen removal is to reduce the loadings below the 8.0 Ibs/ac/year
threshold to qualify for entrance into the buy-down program. The airport intends to purchase credits
. from a mitigation bank to achieve the maximum export rate of 3.6 Ibs/ac/year. Appendix F documents
the proposed removal amounts as summarized in the following table:
Table 6: Nitrogen Removal Summary
Swale
ID Cumulative
Drainage Area (ac) Nitrogen Load
Supplied (lb) Nitrogen Load
Removed (Ib) Weighted Percent
of Removal
GS #1 2.98 24.9 6.1 24.5
GS #2 4.90 39.9 12.8 32.1
GS #3 15.43 65.2 19.2 29.4
GS #4 5.76 30.4 9.3 30.6
GS #5 12.70 78.1 26.6 34.1
GS #6 21.81 152.3 49.4 32.4
GS #7 9.53 21.9 10.4 47.5
I otal 1 133.8
As shown in Table 6, the nitrogen load removal proposed for the grass swales is 133.8 lb. The resultant
annual load reduction from the removal of the asphalt turn-around area in Basins #1 and #5 is 35.9 lbs.
Combining the nitrogen removal of the grass swales and asphalt removal totals 168.9 lbs. This exceeds
the 139.8 lb minimum needed to enter the buy-down program. The net export rate for the site will be
6.4 Ibs/ac/yr.
•
Johnston County Airport Stormwater Design Project Page 3-10
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 4.0
• Water Quantity
To achieve the County's pre versus post requirements for water quantity, a dry pond is proposed in the
abandoned sediment basin located just east of the existing runway (see Appendix A). The dry pond is
needed to offset the increased peak flows that would result due to the construction of the Corporate
Area Development Project. In addition, the County requires that the project limit 10- and 25-year flood
event increases to 10 percent over the pre-project conditions. Appendix H includes a map that shows
the drainage areas delineated for this evaluation, and the proposed dry pond that will attenuate peak
flows. Because no new impervious areas are proposed as part of the Extended Runway Safety Area
project, an analysis of the peak flows was not prepared for this project.
4.1 Methodology
The proposed dry pond was sized using Intelisolve's computer model Hydraflow Hydrographs 2007.
This program simulates the stormwater runoff process to estimate the peak flows for pre- and post-
project conditions. In addition, this program accounts for the attenuation effect that the dry pond with a
riser will have on peak flows. Hydraflow offers a variety of methods for simulating rainfall-runoff
responses and hydrograph development. An NRCS Type II storm was used in conjunction with
precipitation data for the 1-, 10-, 25-, and 100-year frequency with a 24-hour duration. The NRCS
curve number approach was selected to calculate runoff volumes from the precipitation data. Sub-basin
unit hydrographs for these flood volumes were developed using the NRCS lag times.
Hydraflow Storm Sewers 2008 was used to design the closed drainage systems. The hydrology for this
model is based on the Rational Method and intensity-duration-frequency curves for the Johnston County
regional area. The system was designed to pass the 10-year flood event without inundating the rims of
the drop inlets. This program was also used to confirm that the proposed dry pond will not flood the
runway, taxiway, and other upstream infrastructure as a result of the proposed pond improvements.
4.2 NRCS Curve Numbers
Runoff curve numbers (RCNs), which are presented in Appendix H, were generated using the
hydrologic soil group and corresponding existing and proposed landuse. Runoff curve numbers were
developed by weighting the area and corresponding curve numbers for each landuse-soil type
combination. Appendix H includes a NRCS soil map, and the existing and proposed conditions
landuse maps for the watershed. This methodology is based on the NRCS document Urban Hydrology
for Small Watersheds, dated June 1986, and commonly referred to as TR-55.
4.3 Time of Concentrations
Existing and proposed time of concentrations were calculated using GIS topographic mapping and the
proposed grading plan. Time of concentrations calculations are shown in Appendix H. A summary of
all input data is shown in Table 7.
is Johnston County Airport Stormwater Design Report Page 4-1
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 4.0
• Water Quantity
Table 7: Hydrologic Input Data
Basin ID Drainage Area (acres) Runoff Curve
Number (unitless) Time of
Concentration (min)
Existing Basin #1 88.77 69 22.1
Existing Basin #2 51.7 81 13.4
Existing Basin #3 46.51 75 25.9
Existing Basin #4 6.18 56 33.3
Proposed Basin #2 51.7 88 6.3
Proposed Basin #4 6.18 56 33.3
No changes are proposed for the time of concentrations or runoff curve numbers for basins #1 and #3.
4.4 Drainage Basins
Four drainage basins were delineated at the Corporate Area Development Project area in the design of
the proposed dry pond (see Appendix H). These basins were delineated using Johnston County 1-foot
contour interval topographic mapping.
4.5 Proposed Dry Pond Improvements and Results:
The existing runway infield currently is drained by a 60-inch diameter RCP just upstream of the
proposed dry pond. The runway currently has approximately 11 feet of fill over the crown of this 60-
inch diameter RCP. Effectively the runway acts as a dam for large flood events. In addition, the taxiway
on the western side of the airport is approximately five feet lower than the runway. Therefore, when
headwater elevations on the 60-inch diameter culvert exceed six feet over the crown of the pipe, peak
flows will leave the Reedy Creek watershed and divert into the Swift Creek watershed. The runway
culvert and diversion of flows into the adjacent watershed act to limit peak flows that will pass through
the proposed dry pond. Because there is not a history of flooding at the 60-inch diameter RCP, there
are no plans to upsize it. For this reason, the outfall at the proposed dry pond was sized to match the
existing 60-inch diameter RCP at the runway. The following is a summary of the design for the
proposed dry pond:
• Surface Area: The proposed dry pond is larger than the minimum size needed to achieve
the flood reduction goals of the project. The surface area of the pond was achieved by
grading inside the existing abandoned sediment pond. Grading inside the pond will limit
clearing of trees and avoid impacts to the adjacent wetlands.
• Primary Outfall: 33 linear feet of 60-inch diameter RCP with a concrete headwall and
wingwalls.
• Emergency Overflow: 50-foot wide Class B riprap-lined emergency overflow that is
activated in the 10-year flood event. A width of 50 feet was chosen to maximize the
freeboard achieved in a 100-year flood. Because the runway controls the peak flows
downstream, the top of dam elevation will not be overtopped in a 500-year flood.
• Top of Dam: The top of dam is set at elevation 132.00 feet. The total dam height measured
• from the invert of the outfall pipe to the top of dam is approximately 8.8 feet.
Johnston County Airport Stormwater Design Report Page 4-2
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 4.0
• Water Quantity
• Pilot Channel: a proposed four-foot wide riprap-lined pilot channel is proposed to help
minimize erosion for the larger flood events.
•
?J
Because the dry pond is not being used for water quality purposes, a riser and barrel have not been
included in the design of the pond.
The runoff curve number increased from 81 to 88 for Basin #2, and the time of concentration reduced
from 13.4 to 6.3 minutes. This resulted in an increase in the peak flow for the 1-year flood event from
143 cfs to 156 cfs. Increases to the larger flood events were less pronounced due to the control the
existing runway culvert has on the downstream flows. Hydraflow model output has been included in
Appendix I. As shown in Table 8, the proposed conditions peak flows for the proposed conditions 1-,
10- and 25-year flood events are less than the pre-project conditions.
Table 8: Peak Flow Summary at Dry Pond
Peak Discharge, Q (cfs)
Storm Frequency
Existing Conditions Proposed Conditions
w/o Pond in Place Proposed Conditions
w/ Pond in Place
1 Year 143 156 107
10 Year 241 241 235
25 Year 263 263 260
Johnston County Airport Stormwater Design Report Page 4-3
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 5.0
• Culvert Design
The proposed runway safety area will place fill in the stream area encroaching on Reedy Branch, a
tributary of Swift Creek. In order to convey the stream flow through the RSA embankment, a series of
culverts are proposed. A series of triple 10-foot by seven-foot reinforced concrete box culverts achieve
the project goal of not adversely impacting upstream flooding.
5.1 Hydrology
Peak flows used in the design of the proposed culverts are based on USGS regression equations for rural
conditions. Drainage areas were delineated using USGS topographic mapping. Table 9 summarizes
the peak flows used in the sizing of the proposed culverts.
Table 9: Peak Flow Summarv at Pronosed Culverts
Peak Flow 10-year Flood Event
(cfs) Peak Flow 25-year Flood Event
(cfs) Peak Flow 100-year Flood Event
(Cfs)
639 1201 1826
The upstream watershed is relatively flat, and includes numerous roads that have the potential to
attenuate peak flows more than would be normally expected. A detailed hydrologic model would most
likely estimate peak flows that are less than those established with the regional regression equation. For
this reason, the peak flows shown in Table 9 are considered conservative and reasonable for the
purposes of determining impacts to upstream flooding.
5.2 Hydraulic Modeling
The hydraulic analyses of Reedy Creek and the proposed culvert were performed using the US Army
Corps of Engineers' HEC-RAS computer program, version 4.0.0. Cross-sections for the HEC-RAS model
were developed using the WK Dickson surveyed cross sections, and supplemented with the two-foot
contour interval topographic data provided by the County. Channel lengths were developed using
AutoCAD and the stream centerlines provided by HEC-RAS, which allows electronic development of
cross-sections, reach lengths, and other input data from digital topographic mapping.
The culverts have been designed to satisfy US Army Corps of Engineers requirements for maintaining
base flow and aquatic habitat passage. The proposed series of culverts achieve these requirements by
limiting the primary culvert width to 10 feet and burying this culvert 1.0 foot below the existing channel
bottom. A riffle grade control structure is proposed to be buried below the channel bottom on the
downstream side to help dissipate energy and minimize potential for erosion. The culvert configuration
that achieves the culvert design goals is 620 linear feet of triple 10-foot by seven-foot reinforced
concrete box culverts (RCBCs) with headwall and wingwalls. The flanking culverts will be set at the
same invert as the primary culvert, and constructed with a 1.0 foot deep concrete baffle. Results from
the HEC-RAS analysis using this culvert layout are included in Table 10.
• Johnston County Airport Stormwater Design Project Page 5-1
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.
Section 5.0
Culvert Design
Table 10: HEC-RAS Results at Swift Creek Road
Minimum Roadway
25-Year WSEL
100-Year WSEL (ft 100-Year Flood
Elevation Overtopping
(ft NAVD) (Ft NAVD) NAVD) Depth (ft)
Existing

Conditions 144.22 144.61 145.28 1.0
Proposed

Conditions 144.22 144.57 145.31 1.0
Swift Creek Road is a local collector road, and the culvert at this crossing is required to pass the 25-year
flood event without overtopping. As shown in this report, the proposed runway safety area culverts do
not adversely impact the upstream crossing in a 25-year flood. Maintaining a 100-year overtopping
depth of 1.0 feet is considered a sound engineering practice. The proposed culverts at the runway
safety area maintain the existing overtopping depth of 1.0 feet. Therefore, it can be concluded that the
proposed triple 10-foot by seven-foot RCBCs do not adversely impact upstream flooding at Swift Creek
Road.
As shown in Table 11, the culverts do not result in an unreasonably high HW/D. The goal of limiting
the HW/D to 1.2 in the 25-year flood event has been reached. HEC-RAS output for the existing and
proposed conditions is included in Appendix J.
0 Table 11: HEC-RAS Results at Runway Safety Area for Triple 10-ft by 7-ft Culverts
Upstream Culvert 25-Year WSEL (Ft 25-Year HW/D 100-Year WSEL (ft 100-Year HW/D
Invert NAVD) NAVD)
(ft NAVD)
135.18 141.27 1.02 142.24 1.18
5.3 Outlet Protection at Culvert
A buried riffle grade control structure will be installed downstream of the proposed culvert to act as an
energy dissipater to provide protection to the culvert. In addition this structure will reduce the potential
for the downstream channel to erode. The large size of the box culverts disallowed the conventional
methods for rock sizing given in chapter 8 of the NC BMP Manual. Flow depths and velocities were
developed in HEC-RAS, and were used to calculate a shear stress for a 10-year flood event. From the
calculated shear stress, a 50-50 mixture of NCDOT Class A and Class B rock was used as a suitable
liner. Calculations for the channel liner and the HEC-RAS output for the culvert can be found in
Appendix K. Note that in the HEC-RAS output, the culverts are located at River Station 844, with the
middle culvert acting as the base flow culvert, and the lateral culverts acting as the floodplain culverts.
Johnston County Airport Stormwater Design Project Page 5-2
Corporate Area Development and Extended Runway Safety Area Projects
WK Dickson & Co., Inc.

•
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Soil Map-Johnston County, North Carolina
(Johnston County Airport)
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Soil Map-Johnston County, North Carolina
Johnston County Airport
Map Unit Legend
•

I Johnston County, North Carolina (NC101)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
AaA Altavista fine sandy loam, 0 to 2 percent slopes, 70.2 4.9%
occasionally flooded
AmB Appling-Marlboro complex, 1 to 6 percent slopes 12.6 0.9%
AsA Augusta sandy loam, 0 to 2 percent slopes, 54.5 3.8%
occasionally flooded
Bb Bibb sandy loam, 0 to 2 percent slopes, 10.5 0.7%
frequently flooded
Ch Chewacla loam, 0 to 2 percent slopes, frequently 51.4 3.6%
flooded
CoB Cowarts loamy sand, 2 to 6 percent slopes 16.9 1.2%
DoA Dorian fine sandy loam, 0 to 2 percent slopes, 57.4 4.0% 1
rarely flooded
FaB Faceville sandy loam, 2 to 6 percent slopes 6.4 0.4%
GeB Gilead sandy loam, 2 to 8 percent slopes 38.4 2.7%
GeD Gilead sandy loam, 8 to 15 percent slopes 5.3 0.4%
GoA Goldsboro sandy loam, 0 to 2 percent slopes 26.6 1.9%
Le Leaf silt loam, 0 to 2 percent slopes 45.2 3.2%
Ly Lynchburg sandy loam, 0 to 2 percent slopes 25.5 1.8%
McB Marlboro-Cecil complex, 2 to 8 percent slopes 8.9 0.6%
NnB Nason silt loam, 2 to 8 percent slopes 28.5 2.0%
NnD Nason silt loam, 8 to 15 percent slopes 80.3 5.6%
NnE Nason silt loam, 15 to 25 percent slopes 76.8 5.4%
NoA Norfolk loamy sand, 0 to 2 percent slopes 25.9 1.8%
NoB Norfolk loamy sand, 2 to 6 percent slopes 207.0 14.5%
PaE Pacolet loam, 15 to 25 percent slopes 9.9 0.7%
Ra Rains sandy loam, 0 to 2 percent slopes 18.6 1.3%
StA State sandy loam, 0 to 3 percent slopes, 57.0 4.0%
occasionally flooded
Ta Tarboro loamy sand, 0 to 2 percent slopes, rarely 14.3 1.0%
flooded
Tn Toisnot loam, 0 to 2 percent slopes 7.8 0.5%
To Tomotley sandy loam, 0 to 2 percent slopes, 103.7 7.2%
rarely flooded
UcB Uchee loamy coarse sand, 2 to 6 percent slopes 2.4 0.2%
UcC Uchee loamy coarse sand, 6 to 12 percent slopes 3.2 0.2%
Ud Udorthents, loamy 155.6 10.9%
W Water 5.1 0.4%
WaB Wagram loamy sand, 0 to 6 percent slopes 3.4 0.2%
uaUA Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/7/2009
Page 3 of 4
Soil Map-Johnston County, North Carolina Johnston County Airport
Johnston County, North Carolina (NC101)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
Wh Warne loam, 0 to 2 percent slopes, occasionally 22.3 1.6%
flooded
Wt Wehadkee loam, 0 to 2 percent slopes, 115.5 8.1%
frequently flooded
Ww Wehadkee-Chastain association, 0 to 2 percent 64.6 4.5%
slopes, frequently flooded
Totals for Area of Interest 1,431.6 100.0%
USDA Natural Resources Web Soil Survey 8/7/2009
?iii& Conservation Service National Cooperative Soil Survey Page 4 of 4
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Project: Johnston County Regional Airport - Retrofit BMPs for Corporate Area Improvements
Prepared by: DJK Rev by: RWH 03-30-10
• Dated: 1-19-10
Manning's "n" Values Calculated Using USACE Report EM 1110-2-1601
•
Wp 18.823
A 10.12
Rh 0.54
1B
Q 3.17
SS 35
Depth 0.36
BS 0.0101
V 0.523
Wp 29.420
A 16.88
Rh 0.57
VR 0.30
Resultant N Value 0.14
Selected N Value 0.10
4B
Q 11.10
SS 20.0
BS 0.0067
Depth 0.85
V 0.660
Wp 37.0
A 16.88
Rh 0.46
21.1
21.24
1.01
Wp 32.1
A 4.33
Rh 0.13
Wp 32.1
A 14.47
Rh 0.45
Wp 24.3
A 9.72
Rh 0.40
Wp 18.5
A 7.23
Rh 0.39
V 0.589 V 0.620 V 0.52 V 0.894
W, 54.5 Wp 25.4 Wp 17.4 Wp 48.1
A 38.42 A 12.94 A 6.7 A 14.47
Rh 0.71 Rh 0.51 Rh 0.38 Rh 0.30
Wp 19.4
A 21.75
Rh 1.12
0.39 1
V 0.540
Wp 18.8
A 10.09
Rh 0.54
I Rh 1 0.45 1
Wp 20.9
A 6.88
Rh 0.33
Rh 1 0.34 1
Rh 1 0.55 1
Rh 0.49
VR 0.35
Resultant N Value 0.095
S.1-t-i N n 11.1
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Value may not match the VR intersection off Figure 2-5 if the assumed "n" value is capped off at 0.10

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Project: Johnston County Airport
Prepared by: DJK
Dated: 12-20-09
Project Location: Airport T-Hangar Expansion Site
TN Export Coeff.
Type of Land Cover Area (ac) (Ibs/ac/year) TN Export (Ibs/year)

Permanently Protected
Undisturbed Open Space
(forest, unmown meadow) 0.02 0.6 0.0
Permanently Protected
Managed Open Space
(lawn, grass, landscaping) 4.0 1.2 4.8
Impervious Surfaces
(roads, parking
lots,driveways, roofs,
storage areas, gravel
roads) 14.6 21.2 310.4
Totals 18.7 315.3
• Weighted Loading Rate for Site =
Required removal amount to achieve 8 Ibs/ac/yr =
Required removal amount to achieve 3.6 Ibs/ac/yr =
TN Export Removed by Bioretenion Area =
TN Export Removed by Dry Pond =
TN Export Removed by both BMPs =
TN Export from site =
Weighted Loading Rate for Site after BMP =
Cost of buydown per acre =
Buydown payout period =
Buydown amount =
16.86 Ib/ac/yr
165.70 Ibs/yr
247.97 Ibs/yr
164.87 Ibs/yr
11.14 Ibs/yr
176.01 Ibs/yr
139.28 Ibs/yr
7.45 Ib/ac/yr
25.00 $/Ib
30 years
$53,971.40
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A-, A
HCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 1A
II. DESIGN INFORMATION
Site Characteristics
Drainage area 76,055 ft2
Impervious area 26,343 f12
Percent impervious 18.0% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.49 in (interpreted this parameter as depth of flow in Swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 4.28 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter 'Y' below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.58 ft/sec OK
Side slopes 23 :1 OK
Swale length 380.00 ft OK
Swale Characterisfics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 4.00 ft
Width of the top of the swale 55.00 It
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or fill OK
What is the distance from the bottom of the swale to the SHWT? 5.00 ft OK
What is the ground level elevation? 162.15 fmsl
What is the elevation of the bottom of the swale? 161.02 fmsl
What is the SHWT elevation? 156.02 fmsl
What is the longitudinal slope of the swale? 0.800 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and It. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
?y
0
•
0 What is the SHWT elevation? 155.57 fmsl
FMA
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 1 B
II. DESIGN INFORMATION
Site Characteristics
Drainage area 53773 f12
Impervious area 20219 tt2
Percent impervious 20.1% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.36 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 6.41 in/hr
Post-development 10-yr storm peak flow 3.17 U/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ftlsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes
Swale length h
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.52 ft/sec OK
Side slopes 35 :1 OK
Swale length 240.00 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 4.00 It
Width of the top of the swale 84,00 (t
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 5.00 ft OK
What is the ground level elevation? 161.71 fmsl
What is the elevation of the bottom of the swale? 160.57 fmsl

What is the longitudinal slope of the swale? 1.01 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?pF W ATF9OG
> -y
O T
•
•
•
T
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part Ill) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFOWATM
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 2
N. DESIGN INFORMATION
Site Characteristics
Drainage area 213343 ft2
Impervious area 74054 ft2
Percent impervious 25.6% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.83 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 25.57 113/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 fUsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.59 ft/sec OK
Side slopes 31 :1 OK
Swale length 730.00 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the Swale 3,00 ft
Width of the top of the swale 89.00 ft
Additional Inforrnation
Is the Swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 5.00 ft OK
What is the ground level elevation? 160.99 fmsl
What is the elevation of the bottom of the swale? 159.61 fmsl
What is the SHWT elevation? 154.61 fmsl
What is the longitudinal slope of the Swale? 0.47 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W A TF9OG
h ?.
J H
o
•
•
•
A&A
WDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 3
tl. DESIGN INFORMATION
Site Characteristics
Drainage area 671,940.00 1`12
Impervious area 212,415.17 ft2
Percent impervious 23.7% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.93 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 6.41 in/hr
Post-development 10-yr storm peak flow 18.70 1`13lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ftlsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length fl
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.77 ft/sec OK
Side slopes 25 :1 OK
Swale length 600 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 3.00 ft
Width of the top of the swale 129.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.83 ft OK
What is the ground level elevation? 152.13 first
What is the elevation of the bottom of the Swale? 150.66 fmsl
What is the SHWT elevation? 146.83 fmsl
What is the longitudinal slope of the swale? 0.54 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWO)
O?OF W A TFgOG
> y
O -c
•
•
•
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-182-0495
Date February 25, 2009
Drainage area number Grass Swale 4A
II. DESIGN INFORMATION
Site Characteristics
Drainage area 63078.00 ft2
Impervious area 13841.51 ft2
Percent impervious 21.9% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.63 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 3.77 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft /sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit f'For-Credit" Swale. Y (Y or N)
Maximum velocity for 10-yr storm 0.84 ft/sec OK
Side slopes 7 :1 OK
Swale length 491 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the Swale 3.00 ft
Width of the top of the swale 19.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 2.17 ft OK
What is the ground level elevation? 133.91 fmsl
What is the elevation of the bottom of the swale? 132.78 fmsl
What is the SHWT elevation? 130.61 first
What is the longitudinal slope of the swale? 0.58 % OK
What is the depth of freeboard? 0.50 ft OK
Permit Number:
(to be provided by DWQ)
O?QF W A TE9QG
J y
o
Form SW401-Grassed Swale-Rev.4 Parts I and II. Project Design Summary, Page 1 of 19
•
•
•
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Dale February 25, 2009
Drainage area number Grass Swale 4B
A. DESIGN INFORMATION
Site Characteristics
Drainage area 187540.00 ft2
Impervious area 38017.00 ft2
Percent impervious 20.3% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.85 in (interpreted this parameter as depth of flow in Swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 11.10 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ftlsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tallfescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length It
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.66 ft/sec OK
Side slopes 20 :1 OK
Swale length 491 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 3.00 ft
Width of the top of the swale 83.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 2.17 ft OK
What is the ground level elevation? 134.13 fmsl
What is the elevation of the bottom of the swale? 132.78 fmsl
What is the SHWT elevation? 130.61 fmsl
What is the longitudinal slope of the Swale? 0.67 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and It. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W ATF9OG
? r
•
•
•
A
A=10A
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 5
DESIGN INFORMATION
Site Characteristics
Drainage area 552997 ft2
Impervious area 151890 ft2
Percent impervious 20.7% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.91 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 inthr
Post-development 10-yr storm peak flow 16.50 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 fl /sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes
Swale length ft
Optjon 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.71 Nsec OK
Side slopes 25 :1 OK
Swale length 1,231 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 3.00 ft
Width of the top of the Swale 128.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 1.42 ft OK
What is the ground level elevation? 135.01 fmsl
What is the elevation of the bottom of the swale? 133.55 fmsl
What is the SHWT elevation? 132.13 fmsl
What is the longitudinal slope of the swale? 0.54 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W ATF9OG
h ?
o

•
•
F -3 WA
WDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must also be filled out, printed and submitted along with all of the required information.
IL PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 6A
II. DESIGN INFORMATION
Site Characteristics
Drainage area 115280 1t2
Impervious area 22983 ft2
Percent impervious 19.9% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.79 in (interpreted this parameter as depth of flow in Swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 6.77 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft /sec
Soil characteristics (enter "x" below)
Sandisilt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit ("For-Credit' Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.62 Nsec OK
Side slopes 15 :1 OK
Swale length 718 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 ft
Width of the top of the swale 40.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.17 ft OK
What is the ground level elevation? 119.99 fmsl
What is the elevation of the bottom of the swale? 118.70 frisl
What is the SHWT elevation? 115.53 fmsl
What is the longitudinal slope of the swale? 0.54 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
o`'?? W nTe9Qc
O T
•
•
•
A
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 6B
II. DESIGN INFORMATION
Site Characteristics
Drainage area 46798 ft2
Impervious area 15212 ft2
Percent impervious 32.5% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.62 in (interpreted this parameter as depth of flow in Swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 3.49 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tallfescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Optlon 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length fl
Option 2: Swale Seeking Pollutant Credit f'For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.54 ttisec OK
Side slopes 14 :1 OK
Swale length 300 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 ft
Width of the top of the swale 32.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.17 It OK
What is the ground level elevation? 121.70 fmsl
What is the elevation of the bottom of the swale? 120.58 fmsl
What is the SHWT elevation? 117.41 fmsl
What is the longitudinal slope of the swale? 0.54 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?pF W A TF9OG
h ?
J y
o
•
•
•
WDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. OJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kilter, PE
Phone number 919.782.0495
Date February 25, 2009
Drainage area number Grass Swale 6C
C ESI*HItFORMATION
Site Characteristics
Drainage area 219582 ft2
Impervious area 71289 ft2
Percent impervious 32.5% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.88 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 5.39 in/hr
Post-development 10-yr storm peak How 12.06 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter "x" below)
Sandisill (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length It
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.92 ft/sec OK
Side slopes 15 :1 OK
Swale length 1,404 tt OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 fl
Width of the top of the swale 42,00 tt
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y
(Y or N)
OK
What is the distance from the bottom of the swale to the SHWT? 2.25 tt OK
What is the ground level elevation? 124.16 fmsl
What is the elevation of the bottom of the swale? 122.78 fmsl
What is the SHWT elevation? 120.53 fmsl
What is the longitudinal slope of the swale? 0.76 % OK
What is the depth of freeboard? 0.50 tt OK

Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W A TF9OG
? T
•
Permit
A 10"_ WA
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part 111) must also be filled out, printed and submitted along with all of the required information.
r. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782.0495
Date February 25, 2009
Drainage area number Grass Swale 6D
DESIGN INFORAaT-1N
C J
C J
Site Characteristics
Drainage area 46517 ft2
Impervious area 15079 ft2
Percent impervious 32.4% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.73 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 3.46 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 f isec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tallfescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length fl
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.37 ft/sec OK
Side slopes 15 :1 OK
Swale length 300 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 ft
Width of the top of the swale 40,00 fl
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.17 It OK
What is the ground level elevation? 129.88 fmsl
What is the elevation of the bottom of the Swale? 128.65 fmsl
What is the SHWT elevation? 125.48 fmsl
What is the longitudinal slope of the swale? 0.53 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
(to be provided by DWQ)
O?pF W ATF9OG
? y
o
Permit Number:
(to be provided by DWQ)
•
•
•
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 6E
IN. DESIGN INFORMATION
Site Characteristics
Drainage area 54349 ft2
Impervious area 17645 ft2
Percent impervious 32.5% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.70 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 4.05 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ftlsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter 'Y' below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.56 ftisec OK
Side slopes 12 :1 OK
Swale length 349 It OK
Swale Characteristics
Swale Shape: Enter an N" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the Swale 2.00 It
Width of the top of the swale 30.00 It
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.17 It OK
What is the ground level elevation? 135.14 fmsl
What is the elevation of the bottom of the swale? 133.94 fmsl
What is the SHWT elevation? 130.77 fmsl
What is the longitudinal slope of the swale? 0.91 % OK
What is the depth of freeboard? 0.50 It OK
Form SW401-Grassed Swale-Rev.4
Parts I and 11. Project Design Summary, Page 1 of 19
O?O? W ATF9OG
h ?
? T
•
•
0
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part 111) must also be filled out printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kilter, PE
Phone number 919-782.0495
Date February 25, 2009
Drainage area number Grass Swale 6F
A DESIGN INFORMATION
Site Characteristics
Drainage area 46432 ft2
Impervious area 15087 ft2
Percent impervious 32.5% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.62 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 3.46 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 f lsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.52 fUsec OK
Side slopes 14 :1 OK
Swale length 300 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 It
Width of the top of the swale 33.00 It
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the Swale to the SHWT? 3.17 ft OK
What is the ground level elevation? 138.27 fmsl
What is the elevation of the bottom of the swale? 137.15 fmsl
What is the SHWT elevation? 133.98 fmsl
What is the longitudinal slope of the swale? 0.91 % OK
What is the depth of freeboard? 0.50 It OK
Form SW401-Grassed Swale-Rev.4
Parts I and It. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W A TF9oG
h ?
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NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must also be filled out, printed and submitted along with all of the required information.
I. PROJECTINFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 6G
?tt. DESIGN INFORMATION
Site Characteristics
Drainage area 38830 f12
Impervious area 12626 f12
Percent impervious 32.5% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.60 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 2.90 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 Nsec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes ;1
Swale length h
Option 2: Swale Seeking Pollutant Credit ('For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.42 ft/sec OK
Side slopes 16 :1 OK
Swale length 251 fl OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2,00 tt
Width of the top of the swale 37.00 tt
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.17 It OK
What is the ground level elevation? 142.68 fmsl
What is the elevation of the bottom of the swale? 141.58 frisl
What is the SHWT elevation? 138.41 fmsl
What is the longitudinal slope of the swale? 0.91 % OK
What is the depth of freeboard? 0.50 It OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?Of W A TF9OG
J y
O C

•
•
A&VAA
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROTECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Dale February 25, 2009
Drainage area number Grass Swale 6H
II. DESIGN INFORMATION
Site Characteristics
Drainage area 77616 ff2
Impervious area 24975 ft2
Percent impervious 32.2% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.65 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 5.76 ft3/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length tt
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.71 ft/sec OK
Side slopes 16 :1 OK
Swale length 498 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 tt
Width of the top of the Swale 39.00 h
Additional Information
Is the Swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a

recorded access easement to a public Right of Way (ROW)? Y
(Y or N)
OK
What is the distance from the bottom of the swale to the SHWT? 3.17 ft OK
What is the ground level elevation? 145.20 fmsl
What is the elevation of the bottom of the swale? 144.07 fmsl
What is the SHWT elevation? 140.90 fmsl
What is the longitudinal slope of the swale? 0.91 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?O? W ATE9QG
O T
•
•
0
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part ill) must also be filled out printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 61
DESIGN INFORMATION
Site Characteristics
Drainage area 161170 tt2
Impervious area 51038 ft2
Percent impervious 31.7% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.94 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 11.85 ft31sec
velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter 'Y' below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tallfescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length ft
00on 2: Swale Seeking Pollutant Credit ('For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.75 ftisec OK
Side slopes 16 :1 OK
Swale length 1,022 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2,00 tt
Width of the top of the swale 48.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.75 It OK
What is the ground level elevation? 155.28 fmsl
What is the elevation of the bottom of the swale? 153.84 fmsl
What is the SHWT elevation? 150.09 fmsl
What is the longitudinal slope of the swale? 0.64 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts 1 and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?Of W AT,,
J '-I
o
•
•
•
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part III) must also be filled out, printed and submitted along with all of the required information.
I. PROJ FORMATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782-0495
Date February 25, 2009
Drainage area number Grass Swale 6J
II. DESIGN INFORMATION
Site Characteristics
Drainage area 143347 ft2
Impervious area 46175 ft2
Percent impervious 32.2% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.93 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 7.32 in/hr
Post-development 10-yr storm peak flow 10.64 113/sec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length It
Option 2: Swale Seeking Pollutant Credit f'For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.68 ft/sec OK
Side slopes 16 :1 OK
Swale length 931 It OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 2.00 tt
Width of the top of the swale 48.00 It
Additional Information
Is the Swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 3.75 ft OK
What is the ground level elevation? 162.49 fmsl
What is the elevation of the bottom of the Swale? 161.06 fmsl
What is the SHWT elevation? 157.31 fmsl
What is the longitudinal slope of the swale? 0.52 % OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
O?QF W A TF9oG
O T

•
?3-A
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be tilled out, printed and submitted.
The Required Items Checklist (Part 111) must also be filled out, printed and submitted along with all of the required information.
1. PROJECT INFORIUATION
Project name Johnston County Airport - Corporate Area Development Project
Contact name David Kiker, PE
Phone number 919-782.0495
Date February 25, 2009
Drainage area number Grass Swale 7
II. DESIGN INFORMATION
Site Characteristics
Drainage area 414998 ft2
Impervious area 90719 11[2
Percent impervious 21.9% %
Design rainfall depth 1.00 inch
Peak Flow Calculations
10-yr storm runoff depth 0.82 in (interpreted this parameter as depth of flow in swale)
10-yr storm intensity 5.39 in/hr
Post-development 10-yr storm peak flow 18.71 ft3lsec
Velocity
Maximum non-erosive velocity (peak 10-year storm) 3.50 ft/sec
Soil characteristics (enter "x" below)
Sand/silt (easily erodible) X
Clay mix (erosion resistant)
Grass Type (enter "x" below)
Bermuda
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture X
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: N (Y or N)
Maximum velocity
Side slopes :1
Swale length It
Option 2: Swale Seeking Pollutant Credit ("For-Credit" Swale): Y (Y or N)
Maximum velocity for 10-yr storm 0.89 ftisec OK
Side slopes 28 :1 OK
Swale length 900 ft OK
Swale Characteristics
Swale Shape: Enter an "x" in the appropriate cell below:
Trapezoidal X
Parabolic
V-shaped
Width of the bottom of the swale 3,00 It
Width of the top of the swale 70.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? Y (Y or N) OK
Is the BMP located in a proposed drainage easement with a
recorded access easement to a public Right of Way (ROW)? Y (Y or N) OK
What is the distance from the bottom of the swale to the SHWT? 1.92 ft OK
What is the ground level elevation? 134.95 fmsl
What is the elevation of the bottom of the Swale? 133.50 fmsl
What is the SHWT elevation? 131.58 fmsl
What is the longitudinal slope of the swale? 0.44 q OK
What is the depth of freeboard? 0.50 ft OK
Form SW401-Grassed Swale-Rev.4
Parts I and II. Project Design Summary, Page 1 of 19
Permit Number:
(to be provided by DWQ)
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Permit die:
(to be provided by DWQ)
Drainage Area Number:
Grassed Swale Operation and Maintenance Agreement
•
•
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
Important maintenance procedures:
- The drainage area of the grassed swale will be carefully managed to reduce the
sediment load to the grassed swale.
- After the first-time fertilization to establish the grass in the swale, fertilizer will
not be applied to the grassed swale.
The grassed swale will be inspected once a quarter. Records of operation and
maintenance will be kept in a known set location and will be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element: Potential problem: How I will remediate the problem:
The entire length of the Trash/ debris is present. Remove the trash/ debris.
swale
Areas of bare soil and/or Regrade the soil if necessary to
erosive gullies have formed. remove the gully, and then re-sod
(or plant with other appropriate
species) and water until established.
Provide lime and a one-time
fertilizer application.
Sediment covers the grass at Remove sediment and dispose in an
the bottom of the Swale. area that will not impact streams or
BMPs. Re-sod if necessary.
Vegetation is too short or too Maintain vegetation at a height of
long. a roximatel six inches.
The receiving water Erosion or other signs of Contact the NC Division of Water
damage have occurred at the Quality 401 Oversight Unit at 919-
outlet. 733-1786.
Form SW401-Grassed Swale O&M-Rev.3
Page 1 of 2
Permit Numb,
(to be provided by DWQ)
• I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Project name: Johnston County Airport - Corporate Area Development Project
BMP drainage area number:Grass Swales #1 through #7 (see attached plan)
Print name:John H. Bullock, Jr.
Title:Chairman, Johnston County Airport Authority
Address:3149 Swift Creek Road, Smithfield, NC 27577
I, (-1 a 1 e h L • Sj M ryL0 h-k , a Notary Public for the State of
1-?Or4n CAL e, ,vin , County of C ?l Vl 0'w , do hereby certify that
C h 11 11. 1? tat e c/;, ?? personally appeared before me this 1 1-4-'
day of 1,-1 ? t/ c wt h w 00 , and acknowledge the due execution of the
forgoing grassed swale maintenance requirements. Witness my hand and official seal,
?$ IMO
f
NOTARY
r PUBLIC
SEAL
•
My commission expires k , a l?
Form SW401-Grassed Swale O&M-Rev.3
Page 2 of 2
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
0 250 500 "
Feet w e
Johnston County Airport F&WK
1 inch= 500feet Soils Ma WDICKSON
S p community Infrastructure consultants

250 500
Feet
1 inch = 500 feet
N
WE Johnston County Airport
S Existing Landuse Map
WD
IICKSON
community Infrastructure consultants

250 500
Feet
1 inch= 500 feet
N
WE Johnston County Airport
S Proposed Landuse Map
WD
IiCKSON
community Infrastructure consultants

•

SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Existing
Prepared by: NAT
Date: 10/29/2009
Subbasin: 1
Landuse Soil
Group RCN Area
Acres Area (Sq.
Mi. Product of RCN
and Area
1 acre residential B 68 3.54 0.006 241
1 acre residential C 79 0.01 0.000 1
1 acre residential D 84 0.15 0.000 13
Commercial B 92 7.33 0.011 674
Commercial C 94 0.000 0
Commercial D 95 0.45 0.001 43
Open Space (good condition) B 61 33.44 0.052 2040
Open Space (good condition C 74 14.64 0.023 1083
Open Space (good condition D 80 3.07 0.005 246
Woods (good condition B 55 7.31 0.011 402
Woods (good condition C 70 16.14 0.025 1130
Woods (good condition D 77 0.08 0.000 6
Wetlands (woods-poor) B 66 0.000 0
Wetlands woods-poor C 77 0.000 0
Wetlands woods-poor) D 83 0.000 0
Impervious-pavement B 98 1.55 0.002 152
Impervious-pavement C 98 0.22 0.000 22
Impervious-pavement D 98 0.28 0.000 27
Impervious-building B 98 0.000 0
Impervious-building C 98 0.000 0
Impervious-building D 98 0.000 0
Water B 98 0.000 0
Water C 98 0.04 0.000 4
Water D 98 0.52 0.001 51
Totals = 88.8 0.14 6134
Total (weighted) RCN = total product/total area = 69.10
RCN used = 69
LI

•
SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Existing
Prepared by: NAT
Date: 10/29/2009
Subbasin: 2
Landuse Soil
Group RCN Area
(Acres) Area (Sq.
Mi.) Product of RCN
and Area
1 acre residential B 68 0.000 0
1 acre residential C 79 0.000 0
1 acre residential D 84 0.000 0
Commercial B 92 0.000 0
Commercial C 94 0.000 0
Commercial D 95 0.000 0
Open Space (good condition B 61 5.25 0.008 320
Open Space (good condition) C 74 4.82 0.008 357
Open Space (good condition D 80 5.23 0.008 418
Woods (good condition B 55 0.43 0.001 24
Woods (good condition C 70 4.62 0.007 323
Woods (good condition D 77 14.24 0.022 1096
Wetlands woods-poor B 66 0.000 0
Wetlands woods-poor C 77 0.38 0.001 29
Wetlands (woods-poor) D 83 0.11 0.000 9
Impervious-pavement B 98 7.5 0.012 735
Impervious-pavement C 98 3.67 0.006 360
Impervious-pavement D 98 1.59 0.002 156
Impervious-building B 98 2.55 0.004 250
Impervious-building C 98 0.86 0.001 84
Impervious-building D 98 0.45 0.001 44
Water B 98 0.000 0
Water C 98 0.000 0
Water D 98 0.000 0
Totals = 51.7 0.08 4206
Total (weighted) RCN = total product/total area = 81.35
RCN used = 81
0
U
r -l
L_J
SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Existing
Prepared by: NAT
Date: 10/29/2009
Subbasin: 3
Landuse Soil
Group RCN Area
(Acres) Area (Sq.
Mi.) Product of RCN
and Area
1 acre residential B 68 0.000 0
1 acre residential C 79 0.000 0
1 acre residential D 84 0.000 0
Commercial B 92 0.000 0
Commercial C 94 0.000 0
Commercial D 95 0.000 0
Open Space (good condition B 61 28.32 0.044 1728
Open Space (good condition C 74 0.000 0
Open Space (good condition D 80 2.1 0.003 168
Woods (good condition B 55 0.000 0
Woods (good condition C 70 0.000 0
Woods (good condition) D 77 0.000 0
Wetlands (woods-poor) B 66 0.000 0
Wetlands woods-poor) C 77 0.000 0
Wetlands woods-poor) D 83 0.000 0
Impervious-pavement B 98 15.1 0.024 1480
Impervious-pavement C 98 0.000 0
Impervious-pavement D 98 0.43 0.001 42
Impervious-building B 98 0.56 0.001 55
Impervious-building C 98 0.000 0
Impervious-building D 98 0.000 0
Water B 98 0.000 0
Water C 98 0.000 0
Water D 98 0.000 0
Totals = 46.5 0.07 3472
Total (weighted) RCN = total product/total area = 74.66
RCN used = 75
0
0
0
SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Existing
Prepared by: NAT
Date: 10/29/2009
Subbasin: 4
Landuse Soil
Group RCN Area
(Acres) Area (Sq.
Mi.) Product of RCN
and Area
1 acre residential B 68 0.000 0
1 acre residential C 79 0.000 0
1 acre residential D 84 0.000 0
Commercial B 92 0.000 0
Commercial C 94 0.000 0
Commercial D 95 0.000 0
Open Space (good condition) B 61 0.5 0.001 31
Open Space (good condition C 74 0.000 0
Open Space (good condition D 80 0.000 0
Woods (good condition B 55 2.9 0.005 160
Woods (good condition) C 70 0.000 0
Woods (good condition D 77 0.000 0
Wetlands woods-poor B 66 0.000 0
Wetlands woods-poor C 77 0.000 0
Wetlands woods-poor) D 83 0.000 0
Impervious-pavement B 98 0.000 0
Impervious-pavement C 98 0.000 0
Impervious-pavement D 98 0.000 0
Impervious-building B 98 0.000 0
Impervious-building C 98 0.000 0
Impervious-building D 98 0.000 0
Water B 98 2.79 0.004 273
Water C 98 0.000 0
Water D 98 0.000 0
Totals = 6.19 0.01 463
Total (weighted) RCN = total product/total area = 74.87
RCN used = 75

•
SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Proposed
Prepared by: NAT
Date: 10/29/2009
Subbasin: 2
Landuse Soil
Grou RCN Area
Acres Area (Sq.
Mi. Product of RCN
and Area
1 acre residential B 68 0.000 0
1 acre residential C 79 0.000 0
1 acre residential D 84 0.000 0
Commercial B 92 0.000 0
Commercial C 94 0.000 0
Commercial D 95 0.000 0
Open Space (good condition) B 61 5.46 0.009 333
Open Space (good condition C 74 6.58 0.010 487
Open Space (good condition D 80 6.77 0.011 542
Woods (good condition B 55 0.000 0
Woods (good condition C 70 0.86 0.001 60
Woods (good condition D 77 0.41 0.001 32
Wetlands woods-poor B 66 0.000 0
Wetlands woods-poor C 77 0.38 0.001 29
Wetlands woods-poor D 83 0.11 0.000 9
Impervious-pavement B 98 7.71 0.012 756
Impervious-pavement C 98 5.44 0.009 533
Impervious-pavement D 98 11.08 0.017 1086
Impervious-building B 98 2.55 0.004 250
Impervious-building C 98 1.09 0.002 107
Impervious-building D 98 3.26 0.005 319
Water B 98 0.000 0
Water C 98 0.000 0
Water D 98 0.000 0
Totals = 51.7 0.08 4542
Total (weighted) RCN = total product/total area = 87.86
RCN used = 88
•
•
SCS Runoff Curve Number
Project: Johnston County Airport
Conditions: Proposed
Prepared by: NAT
Date: 10/29/2009
Subbasin: 4
Soil Area Area (S

Landuse
Group
RCN
Acres q
Mi.
1 acre residential B 68 0.000
1 acre residential C 79 0.000
1 acre residential D 84 0.000
Commercial B 92 0.000
Commercial C 94 0.000
Commercial D 95 0 000
Open Sp
Open Sp
Open S
Woods
Woods
Woods
Wetlands
Wetlands
Wetland
Wetlands (woods-poor D 83 0.000
Impervio
Impervio
Impervio
Impervio
Im ervio
Impervio
Water
Water
ace (good condition) B 61 3.29 0.005
ace (good condition) C 74 0.000
ace (good condition D 80 0.000
ood condition B 55 2.9 0.005
ood condition) C 70 0.000
ood condition) D 77 0.000
woods-poor B 66 0.000
woods-poor C 77 0.000

us-pavement B 98 0.000
us-pavement C 98 0.000
us-pavement D 98 0.000
us-building B 98 0.000
us-building C 98 0.000
us-building D 98 0.000
B 98 0.000
C 98 0.000
D 98 0.000
Totals = 6.19 0.01
Total (weighted) RCN = total product/total area = 58.19
RCN used = 58
Product of RCN
and Area
0
0
0
0
0
0
201
0
0
160
0
0
0
0
0
0
0
0
0
0
0
0
0
0
360
0
0
Time of Concentration Calculation
SCS Segmental Method
Project: Johnston County Airport
Conditions: Existing W1<
Prepared by:DJK Date: 7-21-09 Q 1G /{:.mss IC3N
Fnginecr, . Thinners . ?iun•eynrs
Ld nd s(a pe Arckiln t s
Existing Basin #1
•
Sheet Flow Segment ID AB
1. Surface description (Table 3-1) Woods
2. Manning's roughness coeff., n (Table 3-1) 0.40
3. Flow length, L (Total < 300 ft) ft 100
4. Two-year 24-hour rainfall, P in 3.6
5. Land slope, S Tr = 0.007(nL)° R ft/ft 0.040
6. Travel time, T t pz 0.550.4 hr 0.26
Shallow Concentrated Flow Segment ID BC
7. Surface description (Paved or Unpaved) Unpaved
8. Flow length, L ft 460
9. Watercourse slope, S v = ao.3zsz<ss ft/ft 0.016
10. Average velocity, (Figure 3-1) ft/sec 2.1
11.Travel time, T t IV,, = 16.1345(x)0.51 hr 0.06
Channel Flow Segment ID CD
12. Cross sectional flow area, A ft 12
13. Wetted perimeter, P ft 8.6
14. Hydraulic radius, R = ft 1.4
15. Channel slope, S ft/ft 0.009
16. Manning's roughness coeff., n 0.045
17
Ch
n
l
l
it
V
.
a
ne
ve
oc
y, 2,3 „Z ft/sec 3.8
18. Flow length, L v = 1.49R s ft 703
19.Travel time, T t n hr 0.05
Time of Concentration = 0.37 hr
Time of Concentration = 22.1 min
n
•
Time of Concentration Calculation
SCS Segmental Method
Project: Johnston County Airport
Conditions: Existing W
Prepared by:DJK Date: 7-21-09 931 C= 1<MO `i t3 N
Engineers . Planners . Suneuors
Landscape Arctrite is
Existing Basin #2
L_J
Sheet Flow Segment ID AB
1. Surface description (Table 3-1) Grass
2. Manning's roughness coeff., n (Table 3-1) 0.24
3. Flow length, L (Total < 300 ft) ft 50
4. Two-year 24-hour rainfall, P in 3.6
5. Land slope, S T = 0.007(nL)°A ft/ft 0.010
6. Travel time, T t pz 0.550.4 hr 0.17
Shallow Concentrated Flow Segment ID BC
7. Surface description (Paved or Unpaved) Unpaved
8. Flow length, L ft 300
9. Watercourse slope, S v, = 20.3282(s)O5 ft/ft 0.005
10. Average velocity, (Figure 3-1) ft/sec 1.1
11.Travel time, T t v„ = 16.1345(s)0 5 hr 0.07
Channel Flow Segment ID CD
12. Cross sectional flow area, A ft 8
13. Wetted perimeter, P ft 7
14. Hydraulic radius, R = ft 1.1
15. Channel slope, S ft/ft 0.008
16. Manning's roughness coeff., n 0.045
17. Channel velocity, V 2,3 „Z ft/sec 3.3
18. Flow length, L v = 1.49R S ft 1097
19.Travel time, T t " hr 0.09
Time of Concentration = 0.33 hr
Time of Concentration = 20.1 min
0
•
Time of Concentration Calculation
SCS Segmental Method
Project: Johnston County Airport
Conditions: Existing
Prepared by:DJK Date: 7-21-09
Existing Basin #3
•
Sheet Flow Segment ID AB
1. Surface description (Table 3-1) Grass
2. Manning's roughness coeff., n (Table 3-1, TR-55) 0.24
3. Flow length, L (Total < 300 ft) ft 100
4. Two-year 24-hour rainfall, P in 3.6
5. Land slope, S T, = 0.007(nL)° x ft/ft
0.007
6. Travel time, T t pz 05 S 0.4 hr 0.34
Shallow Concentrated Flow Segment ID BC
7. Surface description (Paved or Unpaved) Unpaved
8. Flow length, L ft 80
9. Watercourse slope, S v, = 20.32s2<s>° 5 ft/ft 0.016
10. Average velocity, (Figure 3-1) ft/sec 2.0
11.Travel time, T t v = 16.1345(s)0 5 hr 0.01
Channel Flow Segment ID CD
12. Cross sectional flow area, A ft 9.95
13. Wetted perimeter, P ft 20
14. Hydraulic radius, R = ft 0.5
15. Channel slope, S ft/ft 0.120
16. Manning's roughness coeff., n 0.045
17
Channel v
l
it
V
.
e
oc
y, 2/3 12 ft/sec 7.2
18. Flow length, L V = 1.49R S ft 2074
19.Travel time, T t n hr, 0.08
Time of Concentration = 0.43 hr
Time of Concentration = 25.9 min
0
•
Time of Concentration Calculation
SCS Segmental Method
Project: Johnston County Airport
Conditions: Existing VV 1<
Prepared by: DJ K Date: 7-21-09 131= 1< Sph C3 NJ
[.eu7ineets. Planners . `iurvetkirc
t .aud se ape An hile, is
Existing Basin #4
0 9. Watercourse slope, S v, = 20.32s2(s)° 5 ft/ft 0.007
Sheet Flow Segment ID AB
1. Surface description (Table 3-1) Woods
2. Manning's roughness coeff., n (Table 3-1) 0.40
3. Flow length, L (Total < 300 ft) ft 100
4. Two-year 24-hour rainfall, P in 3.6
5. Land slope, S T, = 0.007(nL)° s ft/ft
0.007
6. Travel time, T t p 0.5SO.4
z hr 0.51
Shallow Concentrated Flow Segment ID BC
7. Surface description (Paved or Unpaved) Unpaved
8. Flow length, L ft 200
10. Average velocity, (Figure 3-1) ft/sec 1.3
11.Travel time, T t V„ = 16.1345(,)0 5 hr 0.04
Channel Flow Segment ID CD
12. Cross sectional flow area, A ft 40
13. Wetted perimeter, P ft 20
14. Hydraulic radius, R = ft 2.0
15. Channel slope, S ft/ft 6.000
16. Manning's roughness coeff., n 0.045
17
Chan
l
l
it
V
.
ne
ve
oc
y, 2,3 „Z ft/sec 128.7
18. Flow length, L V= 1.49R S ft 1
19.Travel time, T t n hr 0.00
Time of Concentration = 0.55 hr
Time of Concentration = 33.3 min
0
L I
__J
Time of Concentration Calculation
SCS Segmental Method
Project: Johnston County Airport
Conditions: Proposed W1<
Prepared by:DJK Date: 7-21-09 ?' G 0
Engbrerrs . Ptunners . 5umeyors
Landm ape Architew is
Proposed Basin #2
•
Sheet Flow Segment ID AB
1. Surface description (Table 3-1) Asphalt
2. Manning's roughness coeff., n (Table 3-1) 0.01
3. Flow length, L (Total < 300 ft) ft 86
4. Two-year 24-hour rainfall, P in 3.6
5. Land slope, S T, = 0.007(nL)0' ft/ft
0.005
6. Travel time, T t pz 0.5SO.4 hr 0.03
Shallow Concentrated Flow Segment ID BC
7. Surface description (Paved or Unpaved) NA
8. Flow length, L ft 0
9. Watercourse slope, S v = 20.32s2?s?° ft/ft 0.000
10. Average velocity, (Figure 3-1) ft/sec 0.0
11.Travel time, T t I = 16.1345(5)0 5 hr 0.00
Channel Flow Segment ID CD
12. Cross sectional flow area, A ft Pipe Flow
13. Wetted perimeter, P ft
14. Hydraulic radius, R = ft
15. Channel slope, S ft/ft
16. Manning's roughness coeff., n
17. Channel velocity, V 2,3 12 ft/sec 6.0
18. Flow length, L V = 1.49R S ft 1551
19.Travel time, T t n hr 0.07
Time of Concentration = 0.11 hr
Time of Concentration = 6.3 min
0
0 Stage Storage Relationship - At Proposed Dry Pond
Project: Johnston County Regional Airport
Prepared by: DJK
Dated: 11-08-09 0 1 C+ *-S"4=30 N
I atc/+rrrrrs 1'la rt nWrs ? Surve•uo r+
1 .a ttdsrap.• /arc l+ih•r t..
V,, = Y3 A, + A Incremental volume determined using "conic" method as described in USACE HEC-1 manual
Stage-Storage from Contours
S S
CONTOUR INCREMENTAL ACCUMULATIVE TOTAL
CONTOUR AREA VOLUME VOLUME VOLUME
(FT) (AC) (SF) (GAL) (CF) (ACTT) (GAL) (CF) (ACTT) (%)
124.00 0.02 918 0.000
125.00 0.10 4556 18749 2506 0.058 18749 2506 0.058 0.010
126.00 0.80 34821 129591 17324 0.398 148339 19830 0.455 0.081
127.00 0.89 38610 274529 36699 0.842 422868 56529 1.298 0.231
128.00 0.98 42493 303230 40536 0.931 726099 97065 2.228 0.397
129.00 1.07 46392 332346 44428 1.020 1058445 141494 3.248 0.579
130.00 1.16 50521 362370 48442 1.112 1420815 189935 4.360 0.778
131.00 1.34 58162 406166 54297 1.246 1826981 244232 5.607 1.000
•
•
Stage-Stora ge w/ 25% Reduction to Areas
S S
CONTOUR INCREMENTAL ACCUMULATIVE TOTAL
CONTOUR AREA VOLUME VOLUME VOLUME
(FT) (AC) (SF) (GAL) (CF) (ACTT) (GAL) (CF) (AC-FT) (%)
124.00 0.02 689 0.000
125.00 0.08 3417 14062 1880 0.043 14062 1880 0.043 0.008
126.00 0.60 26116 97193 12993 0.298 111254 14873 0.341 0.061
127.00 0.66 28957 205897 27524 0.632 317151 42397 0.973 0.174
128.00 0.73 31870 227423 30402 0.698 544574 72799 1.671 0.298
129.00 0.80 34794 249260 33321 0.765 793834 106120 2.436 0.435
130.00 0.87 37891 271778 36331 0.834 1065611 142452 3.270 0.583
131.00 1.00 43621 304625 40722 0.935 1370236 183174 4.205 0.750
I:\AdminMKD Interoffice\Columbia\Johnston County Airport\Stormwater Calcs and Report\Dry Pond Design\Spreadsheets-Calcs
Watershed Model Schematic
Hydraflow Hydrographs by Intelisolve v9.22
2 - WS 2 (Pre-dev) 3 - WS 3 (Pre-dev)
1 - WS 1 (Pre-dev)
Comb Apron
4 (Pre-dev)
6 WS 1 (Post-dev)
12 - Infield Storage Pre
7 - WS 2 (Post-dev) 8 - WS 3 (Post-dev) 9 - WS 4 (Post-dev)
7 0-Comb Apron
11 - Infield Storage Post
0 3 - WS 4 and Combine 12 (Pre-dev) Combined
WS 9 and Combine 14 (
C; 5 - Proposed Dry Pond
Corr
Project: Offsite Dry Detention REV 11.04.09.gpw Tuesday, Nov 10, 2009
Hydrograph Return Period Recap HydraflowHydrographsbylntelisolvev9.22
F-
_
L
r
4
yd. Hydrograph Inflow Peak Outflow (cfs) Hydrograph
N
o. type Hyd(s) description
(origin) 1-Yr 2-Yr 3-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr
1 SCS Runoff ------- 48.78 ------- ------- ------- 198.70 282.97 355.88 435.28 WS 1 (Pre-dev)
2 SCS Runoff ------- 87.80 ------- ------- ------- 232.58 304.09 363.69 427.01 WS 2 (Pre-dev)
3 SCS Runoff ------- 36.74 ------- ------- ------- 117.44 160.07 196.26 235.16 WS 3 (Pre-dev)
4 SCS Runoff ------- 0.366 ------- ------- ------- 5.442 9.143 12.52 16.35 WS 4 (Pre-dev)
5 Combine 1, 2, 3, 154.82 ------- ------- ------- 504.54 688.78 845.74 1015.01 Comb Apron
6 SCS Runoff ------- 48.78 ------- ------- ------- 198.70 282.97 355.88 435.28 WS 1 (Post-dev)
7 SCS Runoff ------- 138.20 ------- ------- ------- 305.83 384.97 450.22 519.17 WS 2 (Post-dev)
8 SCS Runoff ------- 36.74 ------- ------- ------- 117.44 160.07 196.26 235.16 WS 3 (Post-dev)
9 SCS Runoff ------- 0.366 ------- ------- ------- 5.442 9.143 12.52 16.35 WS 4 (Post-dev)
10 Combine 6, 7, 8, 185.59 ------- ------- ------- 523.32 698.14 846.64 1006.62 Comb Apron
11 Reservoir 10 156.10 ------- ------- ------- 236.05 255.56 264.97 273.93 Infield Storage Post
12 Reservoir 5 142.56 ------- ------- ------- 235.67 255.18 264.87 273.94 Infield Storage Pre
13 Combine 4, 12 142.74 ------- ------- ------- 240.78 263.05 275.40 287.07 WS 4 and Combine 12 (Pre-dev) Co
14 Combine 9, 11, 156.19 ------- ------- ------- 241.16 263.43 275.57 287.18 WS 9 and Combine 14 (Post-dev) Co
15 Reservoir 14 106.53 ------- ------- ------- 234.92 260.31 273.43 285.58 Proposed Dry Pond
Proj. file: Offsite Dry Detention REV 11.04.09.gpw Tuesday, Nov 10, 2009
4
4
4
Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
yd.
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 48.78 3 729 203,768 ---- ------ ------ WS 1 (Pre-dev)
2 SCS Runoff 87.80 3 720 240,748 ---- ------ ------ WS 2 (Pre-dev)
3 SCS Runoff 36.74 3 732 157,777 ---- ------ ------ WS 3 (Pre-dev)
4 SCS Runoff 0.366 3 750 4,743 ---- ------ ------ WS 4 (Pre-dev)
5 Combine 154.82 3 723 602,292 1, 2, 3, ------ ------ Comb Apron
6 SCS Runoff 48.78 3 729 203,768 ---- ------ ------ WS 1 (Post-dev)
7 SCS Runoff 138.20 3 717 313,646 ---- ------ ------ WS 2 (Post-dev)
8 SCS Runoff 36.74 3 732 157,777 ---- ------ ------ WS 3 (Post-dev)
9 SCS Runoff 0.366 3 750 4,743 ---- ------ ------ WS 4 (Post-dev)
10 Combine 185.59 3 720 675,190 6, 7, 8, ------ ------ Comb Apron
11 Reservoir 156.10 3 723 675,190 10 132.80 18,558 Infield Storage Post
12 Reservoir 142.56 3 729 602,292 5 132.29 10,694 Infield Storage Pre
13 Combine 142.74 3 729 607,035 4, 12 ------ ------ WS 4 and Combine 12 (Pre-dev) Co
14 Combine 156.19 3 723 679,933 9, 11, ------ ------ WS 9 and Combine 14 (Post-dev) Co
15 Reservoir 106.53 3 735 677,427 14 128.82 133,312 Proposed Dry Pond
Offsite Dry Detention REV 11.04.09.gpw Return Period: 1 Year Tuesday, Nov 10, 2009
Hydrograph Report
4
Hyd. No. 14
WS 9 and Combi
Hydrograph type
Storm frequency
Time interval
Inflow hyds.
ne 14 (Post-dev) Combine
= Combine
= 1 yrs
= 3 min
= 9, 11
Tuesday, Nov 10, 2009
Peak discharge = 156.19 cfs
Time to peak = 723 min
Hyd. volume = 679,933 cuft
Contrib. drain. area = 6.200 ac
WS 9 and Combine 14 (Post-dev) Combine
Q (cfs) Hyd. No. 14 -- 1 Year Q (cfs)
160.00 160.00
40.00 140.00
120.00 120.00
100.00 100.00
80.00 80.00
60.00 60.00
40.00 40.00
20.00 20.00
0.00
0 00
0 180 360 540 720 900 1080 1260 1440 1620
•
Hyd No. 14
Hyd No. 9
Hyd No. 11 (min)
Time

r
4
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
(cuft) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(cult) Hydrograph
description
1 SCS Runoff 198.70 3 726 715,136 ---- ------ ------ WS 1 (Pre-dev)
2 SCS Runoff 232.58 3 720 632,121 ---- ------ ------ WS 2 (Pre-dev)
3 SCS Runoff 117.44 3 729 473,015 ---- ------ ------ WS 3 (Pre-dev)
4 SCS Runoff 5.442 3 735 29,111 ---- ------ ------ WS 4 (Pre-dev)
5 Combine 504.54 3 723 1,820,272 1, 2, 3, ------ ------ Comb Apron
6 SCS Runoff 198.70 3 726 715,136 ---- ------ ------ WS 1 (Post-dev)
7 SCS Runoff 305.83 3 717 717,629 ---- ------ ------ WS 2 (Post-dev)
8 SCS Runoff 117.44 3 729 473,015 ---- ------ ------ WS 3 (Post-dev)
9 SCS Runoff 5.442 3 735 29,111 ---- ------ ------ WS 4 (Post-dev)
10 Combine 523.32 3 720 1,905,781 6, 7, 8, ------ ------ Comb Apron
11 Reservoir 236.05 3 741 1,905,783 10 136.66 322,386 Infield Storage Post
12 Reservoir 235.67 3 741 1,820,271 5 136.64 317,688 Infield Storage Pre
13 Combine 240.78 3 741 1,849,383 4,12 ------ ------ WS 4 and Combine 12 (Pre-dev) Co
14 Combine 241.16 3 741 1,934,892 9, 11, ------ ------ WS 9 and Combine 14 (Post-dev) Co
15 Reservoir 234.92 3 756 1,932,386 14 130.86 234,857 Proposed Dry Pond
Offsite Dry Detention REV 11.04.09.gpw Return Period: 10 Year Tuesday, Nov 10, 2009
Hydrograph Report
6
• Hyd. No. 14
WS 9 and Combi
Hydrograph type
Storm frequency
Time interval
Inflow hyds.
Tuesday, Nov 10, 2009
Peak discharge = 241.16 cfs
Time to peak = 741 min
Hyd. volume = 1,934,892 cuft
Contrib. drain. area = 6.200 ac
WS 9 and Combine 14 (Post-dev) Combine
Q (cfs) Q (cfs)
Hyd. No. 14 -- 10 Year
- nn
ne 14 (Post-dev) Combine
= Combine
= 10 yrs
= 3 min
= 9, 11
280.00
240.00
200.00
160.00
120.00
80.00
40.00
0 00
0 180 360 540 720 900 1080 1260 1440 1620
•
Hyd No. 14
Hyd No. 9
Hyd No. 11 (min)
Time
4
4
4
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
(cuff) Inflow
hyd(s) Maximum
elevation
(ft) Total
strge used
(cuft) Hydrograph
description
1 SCS Runoff 282.97 3 726 1,002,170 ---- ------ ------ WS 1 (Pre-dev)
2 SCS Runoff 304.09 3 720 832,188 ---- ------ ------ WS 2 (Pre-dev)
3 SCS Runoff 160.07 3 729 641,259 ---- ------ ------ WS 3 (Pre-dev)
4 SCS Runoff 9.143 3 735 44,954 ---- ------ ------ WS 4 (Pre-dev)
5 Combine 688.78 3 723 2,475,619 1, 2, 3, ------ ------ Comb Apron
6 SCS Runoff 282.97 3 726 1,002,170 ---- ------ ------ WS 1 (Post-dev)
7 SCS Runoff 384.97 3 717 915,849 ---- ------ ------ WS 2 (Post-dev)
8 SCS Runoff 160.07 3 729 641,259 ---- ------ ------ WS 3 (Post-dev)
9 SCS Runoff 9.143 3 735 44,954 ---- ------ ------ WS 4 (Post-dev)
10 Combine 698.14 3 720 2,559,278 6, 7, 8, ------ ------ Comb Apron
11 Reservoir 255.56 3 744 2,559,278 10 137.85 571,539 Infield Storage Post
12 Reservoir 255.18 3 744 2,475,617 5 137.83 566,534 Infield Storage Pre
13 Combine 263.05 3 744 2,520,573 4,12 ------ ------ WS 4 and Combine 12 (Pre-dev) Co
14 Combine 263.43 3 744 2,604,231 9, 11, ------ ------ WS 9 and Combine 14 (Post-dev) Co
15
¦ Reservoir 260.31 3 753 2,601,723 14 131.02 242,990 Proposed Dry Pond
Offsite Dry Detention REV 11.04.09.gpw Return Period: 25 Year Tuesday, Nov 10, 2009
Hydrograph Report
Hydraflow Hydrographs by Intelisolve v9.22
Hyd. No. 14
WS 9 and Combine 14 (Post-dev) Combine
Hydrograph type = Combine
Storm frequency = 25 yrs
Time interval = 3 min
Inflow hyds. = 9, 11
8
Tuesday, Nov 10, 2009
Peak discharge = 263.43 cfs
Time to peak = 744 min
Hyd. volume = 2,604,231 cuft
Contrib. drain. area = 6.200 ac
WS 9 and Combine 14 (Post-dev) Combine
Q (cfs) Hyd. No. 14 -- 25 Year Q (cfs)
280.00
040.00
200.00
160.00
120.00
80.00
40.00
0.00
280.00
240.00
200.00
160.00
120.00
80.00
40.00
0 00
0 180 360 540 720 900 1080 1260 1440 1620
• (min)
Hyd No. 14 Hyd No. 9 Hyd No. 11 Time
4
4
4
Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
yd.
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 355.88 3 726 1,252,960 ---- ------ ------ WS 1 (Pre-dev)
2 SCS Runoff 363.69 3 720 1,001,721 ---- ------ ------ WS 2 (Pre-dev)
3 SCS Runoff 196.26 3 729 785,812 ---- ------ ------ WS 3 (Pre-dev)
4 SCS Runoff 12.52 3 735 59,491 ---- ------ ------ WS 4 (Pre-dev)
5 Combine 845.74 3 723 3,040,491 1, 2, 3, ------ ------ Comb Apron
6 SCS Runoff 355.88 3 726 1,252,960 ---- ------ ------ WS 1 (Post-dev)
7 SCS Runoff 450.22 3 717 1,081,748 ---- ------ ------ WS 2 (Post-dev)
8 SCS Runoff 196.26 3 729 785,812 ---- ------ ------ WS 3 (Post-dev)
9 SCS Runoff 12.52 3 735 59,491 ---- ------ ------ WS 4 (Post-dev)
10 Combine 846.64 3 720 3,120,516 6, 7, 8, ------ ------ Comb Apron
11 Reservoir 264.97 3 747 3,120,519 10 138.46 804,028 Infield Storage Post
12 Reservoir 264.87 3 747 3,040,491 5 138.45 801,133 Infield Storage Pre
13 Combine 275.40 3 741 3,099,981 4, 12 ------ ------ WS 4 and Combine 12 (Pre-dev) Co
14 Combine 275.57 3 741 3,180,008 9, 11, ------ ------ WS 9 and Combine 14 (Post-dev) Co
15 Reservoir 273.43 3 750 3,177,503 14 131.09 247,086 Proposed Dry Pond
Offsite Dry Detention REV 11.04.09.gpw Return Period: 50 Year Tuesday, Nov 10, 2009
Hydrograph Report
10
Hydraflow Hydrographs by Intelisolve v9.22
N
14
H
d
y
.
o.
WS 9 and Combine 14 (Post-dev) Combine
Hydrograph type = Combine
Storm frequency = 50 yrs
Time interval = 3 min
Inflow hyds. = 9, 11
Tuesday, Nov 10, 2009
Peak discharge = 275.57 cfs
Time to peak = 741 min
Hyd. volume = 3,180,008 tuft
Contrib. drain. area = 6.200 ac
WS 9 and Combine 14 (Post-dev) Combine
Q (cfs) Hyd. No. 14 - 50 Year
280.00
040.00-
200.00
160.00
120.00
80.00
40.00
0.00
Q (cfs)
280.00
240.00
200.00
160.00
120.00
80.00
40.00
0 00
0 180 360 540 720 900 1080 1260 1440 1620
•
Hyd No. 14
Hyd No. 9
Hyd No. 11
Time
(min)
11
4
Hydrograph Summary Report
Hydraflow Hydrographs by Intelisolve v9.22
4
4
yd.
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
(cult) Hydrograph
description
1 SCS Runoff 435.28 3 726 1,528,677 ---- ------ ------ WS 1 (Pre-dev)
2 SCS Runoff 427.01 3 720 1,184,275 ---- ------ ------ WS 2 (Pre-dev)
3 SCS Runoff 235.16 3 729 942,921 ---- ------ ------ WS 3 (Pre-dev)
4 SCS Runoff 16.35 3 735 76,024 ---- ------ ------ WS 4 (Pre-dev)
5 Combine 1015.01 3 723 3,655,873 1, 2, 3, ------ ------ Comb Apron
6 SCS Runoff 435.28 3 726 1,528,677 ---- ------ ------ WS 1 (Post-dev)
7 SCS Runoff 519.17 3 717 1,258,952 ---- ------ ------ WS 2 (Post-dev)
8 SCS Runoff 235.16 3 729 942,921 ---- ------ ------ WS 3 (Post-dev)
9 SCS Runoff 16.35 3 735 76,024 ---- ------ ------ WS 4 (Post-dev)
10 Combine 1006.62 3 720 3,730,551 6, 7, 8, ------ ------ Comb Apron
11 Reservoir 273.93 3 750 3,730,550 10 139.06 1,068,027 Infield Storage Post
12 Reservoir 273.94 3 750 3,655,873 5 139.05 1,068,319 Infield Storage Pre
13 Combine 287.07 3 741 3,731,897 4, 12 ------ ------ WS 4 and Combine 12 (Pre-dev) Co
14 Combine 287.18 3 741 3,806,575 9, 11, ------ ------ WS 9 and Combine 14 (Post-dev) Co
15
I Reservoir 285.58 3 750 3,804,066 14 131.15 250,686 Proposed Dry Pond
Offsite Dry Detention REV 11.04.09.gpw Return Period: 100 Year Tuesday, Nov 10, 2009
Hydrograph Report
12
Hyd. No. 14
WS 9 and Combi
Hydrograph type
Storm frequency
Time interval
Inflow hyds.
ne 14 (Post-dev) Combine
= Combine
= 100 yrs
= 3 min
= 9, 11
Tuesday, Nov 10, 2009
Peak discharge = 287.18 cfs
Time to peak = 741 min
Hyd. volume = 3,806,575 cuft
Contrib. drain. area = 6.200 ac
WS 9 and Combine 14 (Post-dev) Combine
Q (cfs) Hyd. No. 14 -- 100 Year Q (cfs)
320.00
080.00
240.00
200.00
160.00
120.00
80.00
40.00
0.00
320.00
280.00
240.00
200.00
160.00
120.00
80.00
40.00
0 00
0 180 360 540 720 900 1080 1260 1440 1620

Hyd No. 14
Hyd No. 9
Hyd No. 11 Time (min)
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LOC 0 LIST OF DRAWINGS
N.T.S. N.1'.S,
C-1 -COVER SHEET C-19 -DRAINAGE AND EROSI AND EROSION CONTROL DETAILS & NOTES SHEET ~1
C-2 -CONSTRUCTION SAFETY PLAN C-20 -DRAINAGE AND EROSI AND EROSION CONTROL DETAILS ~ NOTES SHEET ~2
C-3 -GENERAL NOTES AND LEGEND C-21 -DRAINAGE AND ERO51 AND EROSION CONTROL DETAILS NOTES SHEET ~3
C-4 -CORPORATE AREA LAYOUT AND STAKING PLAN C-22 -DRAINAGE AND EROSI AND EROSION CONTROL DETAILS ~ NOTES SHEET ~4 c~,~- I, I ~ , ~ il`t f~ ,r~r~;' `
G-5 -RUNWAY SAFETY AREA LAYOUT AND STAKING PLAN C-23 -BOX CULVERT DETAIL /ERT DETAILS SHEET ~1 t, ~
- - P AT A A ARIN AN GRUBBING DEMOLITION AND INITIAL EROSION C-24 -BOX CULVERT DETAIL G 6 COR OR E RE CLE G D y y /ERT DETAILS SHEET ~2 ~ : . ~ , 4,~ .
CONTROL PLAN
C-25 -TYPICAL SECTIONS AI SECTIONS AND MISCILLANEOUS DETAILS
C-7 -RUNWAY SAFETY AREA CLEARING AND GRUBBING AND DEMOLITION PLAN
C-26 -WETLANDS DELINEATI( ~ DELINEATION MAP SHEET #1
C-$ -CORPORATE AREA PHASE 1 GRADING AND DRAINAGE PLAN SHEET ~1
C-27 -WETLANDS DELINEATI( ~ DELINEATION MAP SHEET ~2 ~ ~i~' ~ ; 1 l~~i:
C-9 -CORPORATE AREA PHASE 1 GRADING AND DRAINAGE PLAN SHEET ~2 I;i ~ 1
C-2S -DRY DETENTION PON[ :NTION POND DETAIL SHEET - E ~ x, , ~
C-10 -RUNWAY SAFETY AREA GRADING AND DRAINAGE PLAN y ~ 11
C-29A -DRAINAGE AREA MA ~E AREA MAP I~ ~``4 t~x~„~ ~ E~ . `
C-1.1 -CORPORATE AREA PHASE 2 GRADING AND DRAINAGE PLAN SHEET ~1 t~®~UCl9~ ICl~I'a~5~ClJ~U6'e C~fl1Sll~'C.~C~'~S
C-29B -SWALE CONSERVATId ;ONSERVATION EASEMENTS
C-12 -CORPORATE AREA PHASE 2 GRADING AND DRAINAGE PLAN SHEET ~2
C-30A -BMP SWALE ~3 GRA ALE ~3 GRADING AND EROSION CONTROL 1001 PINNACLE P®lNT DRIVE
C-13 -DRY POND GRADING AND EROSION CONTROL C-306 -BMP SWALE 5 GRA ALE 5 GRADING AND EROSION CONTROL SUITE 110
C-14 BORROW AREA GRADING, EROSION AND SEDIMENT CONTROL PLAN G®LUMBIA, SC 29223
C-30C -BMP SWALE ~6H A~ ALE ~6H AND GRADING AND EROSION CONTROL (803D 7864261
C-15 -RUNWAY SAFETY AREA CULVERT PLAN AND PROFILE
X--1 -RUNWAY SAFETY AREA 4FETY AREA CROSS SECTIONS STATION 12+00 THROUGH 13.00
C-16 - CORP AREA E&SC 1 USE DESC ON TITLE SHEET Office Locations:
X-2 - RUNWAY SAFETY AREA AFETY AREA CROSS SECTIONS STATION 14+00 THROUGH 16+00 North Carolina Georgia
C-17 - CORP AREA E&SC 2 USE DESC ON TITLE SHEET
X-3 - RUNWAY SAFETY AREA AFETY AREA CROSS SECTIONS STATION 17+00 THROUGH 20+00 South Carolina Kentucky
C-18 - RUNWAY SAFETY AREA EROSION AND SEDIMENT CONTROL PLAN
WKD JOB # 60324.00.CA

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_ ~ ~ ~ SWALE ~1 A ~ A
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Z s,. .~...rr ~ v~ ~ . ~..e, ~ _,J ~ PROPOSED SWALE #3 _ F~
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NOTE:
SUB-BASIN BOUNDARIES FOR SWALE 6 BASED ON LOCATION Of % Ili 1°~mtls ~,"alcs ftDi' Grass male basins ~,~..w..k,.....~,M~.
DRAINAGE INLETS OF SLOPE DRAINS. ~ E F
E Existing Proposed
~dividual % VVe l+Veighted % Weighted %
Sv~ale ID Imperious Area (it sq} Grass Area sq} Indiv Area (ft sq) Indiv Area {ac) Impertiiaus Tatal Area (ac) Im i Area (ac) Impervious Impen~ious
1A 13677 62378 76055 1.75 17.98°l0 1.75 1.75 34.6% 17.98%
1 B 10811 42962 53773 1.23 20.10% 2.98 2.98 35.9% 18.86°!0
2 54562 158781 213343 4.90 25.57% 4.90 4.90 34.7% 25.57%
3 77821 250948 328769 7.55 23.67% 15.43 4A .13842 49236- 63078 1.45 21.94% 1.45 15.43 31.6% .23.59% 1.45 2i.9% 21.94%
4B 38017 149523 187540 4.31 20.27% 4.31 4.31 20.3% 20.27%
5 114387 438610 552997 12.70 20.68% 12.70 12.70 27.5% 20.68%
fiA 22983 92297 115280 2.65 19.94% 2.65 2.65 19.9°10 19.94%
6B 15212 31586 46798 1.07 32.51°k 1.07 1.07 32.5% 32.51 %
6C 71289 148293 219582 5.~1 32.47°Ao 5.04 5.04 32.5% 32.47°~
6D 15079 31438 46517 1.07 32.42% 1.07 1.07 32.4% 32.42%
6E 17645 36704 54349 1.25 32.47°l0 1.25 1.25 32.5°k 32.47°/0
6F 15087 31344 46432 1.07 32.49% 1.07 1.07 32.5% 32.49%
6G 12626 26204 38830 0.89 32.52% 0.89 0.89 3z.5% 32.5z% GRAPHIC SCALE 1.78 32.3% 32.18%
6H 24975 52641 77616 1.78 32.18% 1.78 61 51038 110133 161170 3.70 31.67°k 3.70 3.70 31.7% 31.67% roo o so sao iao Sao
6J 46175 97172 143347 3.29 32.21 % 3.29 3.29 32.2% 32.21 %
7 90719 324279 414998 9.53 21.9% 9.53 9.53 22.9% 21.86%
E E I (IDt FEET ~
E E 1 lllC),3 - 100
(-CRT ROJECT MANAGER DRAWING SCALE 1001 PINNACLE POINT DRIVE RELEASED FOR DATE 1 ADDED SHEET „ AS SHOWN SUITE 110 ER SA AN[ ;SA AND CORPORATE AREA DEVELOPMENT C-29
2 UPDATED SHEET FOR SWALE DEIGN 25 10 QRAriN BY PROJECT DATE COLUMBIA, SC 29223 APPROVALS 3 UPDATED PLAN PER DWQ REVIEW 3 02 1 RWH Nov 2009 WK [phone] FOR THE DRAINAGE AREA MAP
APPROVED BY PROJECT NUMBER BIDDING
80324.00.CA 1pD1(0.Nvx%'cjW"N Office Locations: CONSTRUCTION J DEC JOHNSTON COUNTY AIRPORT -30
REV. NO. DESCRIPTION DATE FILE NAME PLOT DATE commundty infrastructure consultants North Carolina Georgia lina Kentuck RECORD DWG. SMITHFIELD, NORTH CAROLINA
RECISIONS South Caro NQ UMSE N E--Q-741

~ ~
~ SWALE #5 CONS ~WW , ALE ~5 CONSERVATION EASEMENT LIMITS
AF APPROXIMATELY 123' X 1275'
~ • • SWALE #7 CONSERVATION EASEMENT LIMITS > APPROXIMATELY 90' X 917'
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SWALE #6 CONSERVATION EASEMENT LIMITS
APPROXIMATELY 48' X 6087
SWALE ~1B CONSERVATION EASEMENT LIMITS :MENT LIMITS SWALE #1A CONSERVATION EA5EMENT LIMITS
APPROXIMATELY 84 X 260 ( 84' X 260' APPROXIMATELY 55' X 400'
1.1 .____~__.______.w_._~
c ~
SWALE 4A CONSERVATION EASEMENT LIMITS ~ I p t ~ f
!j APPROXIMATELY 19' X 511' ~ - TTTTTTT TTT ~ TTTT TTTTTT

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T~ ~ t? S F' t'~ ~r ~f tea' J=-~ 'P - f~ :9' .r ..L ~.I r''afi"' e` X Y p= F`w .tom-~ - ..Y. _ f ~ ~ ,t ~ f J ,"'r~ X ,F r' s rs fit >a ,p ~r r,`` r r. ~I`L „ r r
Z I' SWALE ~4B CONSERVATION EASEMEN L TS ~ f'. ~ ~ ~ r .r f ; ^s fr ~ ,r 4 fi. p~ f i fi i is~
APPR XIMATELY 83' X 511' ~ f r m, o r F. j
~ ! 4 ~ _S r' 6'~ r .;a J. ` i , ~ r' p ~ F , ~ ~ ~ p,v ~,.J J" 'J 1 V 1 .a r' f : h"'~~ ,a" ,d r J d { r~~ a ,o-' t'' r'F 1 J t
~ f~
~ SWALE 3 CONSERVATION EASEMENT LIMITS t' ~ 'j ~ SbVALE ~2 CONSERVATION EASEMENT LIMITS ~t, ~
o o APPROXIMATELY 129' X 720' 0 J l Ij ° ~ ° APPROXIMATELY 89' X 750' ° ;
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„ut r ~ ~Y r` ` t 3 fir' f„.„ P` 1'~ F, X~ r ,r~ St J~* 1~' ! S ?9 d F f'- r° ~ r' fir: s d` ~ 1'j : . F' s . l' P - ~ F ~ .R r dfi _a..~' ,p" ~"':.f°` "M r r f, , ~ F s" ~ f ~r.~ „ ~ ~,.a it .~~Y<'.r ,~OF,d` ~x^*" rx" yf,..'' ,,,'`~1
% : " ~ F~ _ ^f ~ r .u" .,".b,,:.. ~ x"w''~ .,,,~,,~",«.~,-...,K.,., ~ fir'' ~ ,r~-' rt ...V q' ' w,,.n,.~ . ,:„-«e...° , z ,o .,d- -a•,,.x .,:..~w.. ..~..a,aK,~.~t:.r. ~...;r..,.,,". .M~ ,..yd.< w,a ice}-.... s yam.y _ i' s a+i~~," ems"? W:m a',„.,,~{.~~„f "'c"'.."'T.. k£ ,°s"' . ® a ~.a.a"'~re ~ ~ as,.,,.,. i.-~ .ry ,a ~.-^.v.~ ~ -z ..u. ,l ~`d: :.,a,v-m.,.,~.,..,.,:..~ ~.,a.a ,d®r~.. M«.'' dy~'~... ~ ,.,.i .„„~C'~ :..a'' ,laf
".off tee' ~.;a.._s-=...a ,
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I SWALE ~6 CONSERVATION EASEMENT LIMITS
X APP XIMAT 4 7 RO ELY 8 608 I

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1 inch = 100
PROJECT MANAGER DRAWNG SCALE 1001 PINNACLE POINT DRIVE RELEASED FOR DATE
1 ADDS SHEET 420010 CRT AS SHO1Nd SUITE 110 ERSA AND COLUMBIA, SC 29223 APPROVALS SA AND CORPORATE AREA DEVELOPMENT C- 219
2 UPDA SHEET FOR SWALE DESIGN DRAWN By PROJECT DATE RiMd NOV 2009 'u [phone] 3 UPDATED PLAN PER D REVIEW 3 02 10 FOR THE SWALE I
APPROVED BY PROJECT NUMBER BIDDING
- - _ la QJC 80324.00.CA Office Locations' CONSTRUCTION J JOHNSTON COUNTY AIRPORT 4 EA.~IEMENTS -30
REV. N0. DESCRIPTION DATE ALE NAME PLOT DATE community intastructure consultants North Carolina Georgia South Carolina Kentucky RECORD DWG. SMITHFIELD, NORTH CAROLINA
REVISIONS

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YA t 3 4 ' a~~~~. ~ W PIPE IPR RI AP L®
w ~r~4 u r SIZE (IN) Clays DEPTH (I) (FT) (FT)
Y~Y F'"' rye/ ai~ - ` m e ~ ~ n 24° 50=10~ 15 15° 10°
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~ ° ~ REMOVE EX. ATE . , AND INLET 130. IX.
~ w CUL T TO R AIN ` C TION E ICATIO
~ IN PLACE, SWALE G SWALE H - SWALE ~6H SWALE 1. ENSURE THAT THE SUGRADE FOR THE FIL FI AND RIPRAP FOLLO THE REQUIRED LINES AND ADES SHO
IN E PLAN. COMPACT ANY FILL REQUIRED IN THE SUSGRADE TO THE DENSITY OF THE .SURROUNDING
`,Y ti ~ - ~ M. UNITUED MATERIAL LOW AREAS IN THE SU GRADE UNDISTURBED SOIL MAY ALSO E FILLED GY
~ , , T o , ~ ~ r . ..~,a~.,:a..,, _ ~ T:,___.____ INCREA~NG E RIPRAP THICKNESS.
~ ,w ..a M~,~ ,~~~r X..12, ~ . ~ M,o.. .
,.~._,.m EX. 'tE AND w.....~, RAE',. ~ RCP 2. E RIPRAP AND GA FILTER MUST CONFORM TO THE PECIFI ADING LI I THE P
a ~.~~,m...~~, EX 12 n" CDC:' 1Aii~~, ...wn.,. ' 3. FILTER CLOTH, EN USED, MUST MEET DESIGN REQUIREMENTS D 9E PROPERTY PROTECTED FROM PUNCHING
,~ro..~ .w.,k,~~ ~r.~~ ,.~w.., r~ ~ ffi~ w ~ m,~ _ ~ ~ ~ I OR ARING DURING INSTALLAl10N. REPAIR PINY DAMAGE SY REMOVING THE RIPRAP AND PLACING ANOTHER
,,,na,, '""~w~~ . t.w a..._.:w.~ spa,.., ~ i f PIECE OF FlL CLOTH OVER THE DAMAGED ~ EA. ANY C NEGT1G J~NTS LD OVERLAP A MINIMUM OF
.m„ ~ . ~ 1 FOOT. IF THE DAMAGE I EXTENSIVE, REPLACE ENTIRE FlL CLO .
SWALE 6H PROPOSED DRAINAGE IMPROVEMENTS
1"=50' 4. RIPRAP MAY E PLACED SY EQUIPM~T, SLIT TAKE CARE TO AVOID DAMAGING THE FILTER.
ROCK FILTER 5. THE MINIMUM THICKNESS OF THE RIPRAP SHOULD SE 1.5 TIMES THE MAXIMUM STONE DIAM .
RING ®Q
. RIPRAP MAY DE FI STONE OR ROUGH QUARRY T E. IT SHOULD DE HARD, ANGULAR, HIGHLY
ATHE®ESIT T AND WELL GRADED.
RIPRAP OUTLET 7. CONSTRUCT THE APRON GRADE AS SHO ON THE PLAN TH NO OVEFALL AT E END. MAKE THE TOP
SEE DETAIL, 1 THE RIPRAP AT E DO STREAM END LEVEL E RECEIVING AREA SLIGHTLY FLOW IT
THIS SHEET. C°
S. ENSURE THAT E APRON f PR ERTY ALIGNED THE RECEIVING S EAM AND PR LY STRAIGHT
~ THROUGHOUT I LENGTH. IF A CURVE IS NEEDED TO FlT SITE CONDITIONS, PLA IT I THE UPPER SECTf M~.,.... , ~ OF THE RO.
.~...m. ..,,M... a~ ~ ~
r r' ..,cn .,».2:..„, r<.,>Nm ~ x..;. .~ma... .M,..,„, . ,w ..,M .,a r.~ ,.,w :.>r., a. c.~ „r L~ . .:M s- ,T .v..o.-..+ .~.w..... N....~::a: w.,,..-v~ .d.~.wb... ,-:.«a-. ..rra-.~.-. ~.,..v..,,.. ~ . ....a. M -m- w.i: y ~ .a ~ ~ -
qa" - ~ d~ w.. ~ G . ~ ° ~ _a 9. IMMEDIATELY A R CONS UCTION, STABILIZE ALL DISTURGED AREAS WITH VE TATION.
,r ,t°° ~ ~ v _.Mb .~s~. w,. ~,~X ~ ~ ~ a _~r~ m ~ X 12" __w~w ~ PROP 24 P 24~ ~ r ~ `i o-.q . o-- ~ .
~ RCP r`' , ,~:r, ~.a RCP RCP i' ,r, .r l
INSPECT RIPRAP OUTLET STRUCTURES AFTER HEAVY RAINS TO SEE IF ANY EROSION AROUND OR QELOW THE
F F` > ~ ~ 5`r e # ~ RIPRAP HAS TAKEN CE IF ST ES HAVE N DISL ED. IMMEDIA Y AKE ALL NE PAIRS TO
d" »w4.. "~~.r !N PREVENT FURTHER DAMAGE.
r ~ ~ ~
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~ r' r T " ~ r'' OVE EX. GRATE E~. ATE, ~ _I INLET I$Ok AND 12m ' ~ ,,4Y
1~ ~ < j ~ REM01~ EK, GRATE ar ~ AND INLET COX. ~ PIPE. INSTALL
J° ~ ~ f AND INLET ®0~, „ ,r fi REMOVE EK, PLUG AND A9ANDON ~ s s~` f ~ PLUG D ...W GRATE INLET E~, CUL T. ~.~DO~ ~ ~ -30C NT T scALE
q~~°' O ®OX. BUG AND ~ . s- ~ INLET E30X APd~~4" 5 ~
~ ~ , ab ~ ~DANDCN EX. ~ , e r. L, PIPE. 5, C~ 1
r~ spa. ~ ~ CULVERT. r ~ ~ ~ I r f ~ A' ~ ~ 3 f~ ° ® I i
r s n.. g , ~a t" = k a gr" F~ I~s}
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SWALE 7 PROPOSED DRAINAGE IMPROVEMENTS
1" = 5a'
PERMANENT SEEDING. SEE NOTES;
SHEET C-18 FOR SEEDING SCHEDULE, 1. NO ACTIVITY SHALL OCCUR CLOSER THAN 79' TO ANY AC11VE TAXIWAY OR 150' TO ANY ACTIVE RUNWAY WITHOUT COORDINATION WITH
THE RPR, UNLESS OTHERWISE NOTED,
2. CONSTRUCTION ACTIVITY WITHIN THE TSA/OBSTACLE-FREE ZONE IS PERMISSIBLE WHEN THE TAXIWAY IS OPEN TO AIRCRAFT TRAFFIC IF ADEQUATE WINGTIP CLEARANCE EXISTS BETWEEN THE AIRCRAFT AND EQUIPMENT/MATERIAL; EXCAVATION, TRENCHES, OR OTWER
CONDI710NS ARE CONSPICUOUSLY MARKED AND LIGHTED; AND LOCAL NOTAMS ARE IN EFFECT FOR THE ACTIVITY (SEE AC
150/5300-13 FOR WINGTIP CLEARANCE REQUIREMENTS.} THE NOTAM SHOULD STATE THAT, "PERSONNEL AND EQUIPMENT ARE WORKING Bd Q 26 ~ 9~ 2~ I~.__T_ i i _ . _ _ ~
ADJACENT TO TAXIWAY "A"°, ~ ~ t , ~f _ i
3. EXISTING SWALES #6H AND #7 MEET ALL REQUIREMENTS FOR DEPTH AND VELOCITY BASED ON EXISTING SHAPE AND SIZE.
CONTRACTOR TO ENSURE POSITIVE DRAINAGE AT LOCAl10NS WHERE INLETS WILL BE REMOVED ON SWALES #6H ANp ,~7.
1 iaaoh = 50 it ~9 ~ ~ ~ ~ ~ ~ ~ ~ l Y ~ ~ ~ ~ f ~ ~s~° 3 ~ f i j ` F i
t
PROJECT MANAGER DRAWING SCALE 1001 PINNACLE POINT DRIVE RELEASED F DATE
1 ADDED SHEET 15 90 CRT AS SHOW - SUITE 110 RSA AND CORPORATE AREA DEVELOPMENT C-30
DRAWN BY PROJECT DATE COLUMBIA, SC 29223 APPROVALS RWH NOV 2009 . [phone] FOR THE BMP SWALE #61-1 AND #7 GRADING
f 1, jl BIDDING APPROVED BY PROJECT NUMBER C'~`:~
DJK 80324.00.CA Office Locations: a REV. N0. DESCRIPTION DATE HLE NAME PLOT DATE community infrastructure consultants North Carolina Georgia CONSTRUCTION JOHNSTON COUNTY AIRPORT AND EROSION CONTROL -30
South Carolina Kentuck RECORD DWG. SMITHFIELD, NORTH CAROLINA
REVISIONS NQ UCMSF NQ- F-M74

o~?&& 7S DIRECT/p/V pF FLOW D/RECT/pN OF FL
# ?W~ J ,
bo ~
~ ~ ~ EDGE OF J F3 c~W TAXIWAY I x
~ = 151.48 STAPLE AT 1' INTERVALS START NEW
~ r FOC / ~ EXISTING ~ ROLL IN CHECK
4.~ ~ . " .x TAXIWAY A . EDGE OF / ~ ' SLOT, OVERLAP
4 ~ SEE NOTE 2. TAXIWAY 1 ti _ ,~,IEIIEII~" ~ MINIMUM t' °:~::a:. ,
~ ,q a. -156.60 M PROPOSED r s>t ~Il~lil~ll~{I~II~II II I_ ~.:;:,~_r:..: ~ ~ -11~II~II~II~II~II~IICI1~1 ~I::~~;"~ : II~II~I1~11 II I II Il~ll~ll~fr~ III-III~II~I~I~II~IIGill=11:,x'::;,;:.:.° -I~~ _ `r 6°
2 , oa~ f ORARY ~ al~ll~ll~ll~ll ICI ° l~ll~l~ll~ l2° ~I~II~II~II~II~II~II~II i ~l i I " -l l 1=I I ~I I ~I I ~I 11~ 11~I I ~ I I~ I ~ I f~i l El l -
~ CHE AM BMP ~(dAlE,1~ (597 ~ I -I I -111_11 I ~ ~I l ~i l ~l l X11 1-i l ~l I I I I I I I I~ 11=111 1{-
F ~ ~ -z ( ) LF ®0.0054 ~(~P,,, ~_.w T . PROPOSED ' I - II-II~II~II~ ''i~l~l~l~l~l~ll I i II~II~11~11~ 'I J~-1I-III=III=IIr ~I~-il~ilf~ II~II~II_ IIF_
~ 'o SPREADER 2 ~8 4 25.1 SIDE. l a~ = 149.25 C-30A I iii_III IIhI~~II"
PRPOSED x '`'8 ~ v iS5 ~ W ~ TEMP Y " ~ ~ `b„ 6'
~ PROPOSED 12 WIDE g pROpOg~„~,0 ROCKS 1 T i I < ACCESS EASEMENT " 12° 6°
~ ~ DIKE CHECK ~ , , SPUTTER / " _ C-30 FIGURE 2
FIGURE 1 INTERMITTENT CHECK SLOT
INTITIAL ANCHOR BEGINING OF NEW ROLL
TRENCH
w ~ ~ - v.r / ...wti w.,, ~ DIRECT/p/~ pF FLOW---_~
_ _ ~ . _ / ~ , _ .,a ~V~ 1'
i y, Y ,rte ? a,„,~»..» .rob ~ - _ ~ STAPLE AT 1 ~ i' STAPLE AT 1
. y~ ;t.a INTERVALS INTERVALS
„ aa r _ ~ g ~ ~ e~~
m~ ~ .r L!1 .,M,. r ~
F~~ r ~14g i Uo I , O ~ O 0~
a". a ~ .~,~,,.w ,..N Z rc-~ , ,,I y_~ 5 , , ~ PROP 36~ I _I •..~ilk=i~~ 4° 12' ~ I~II~II~I~I.I..I.~.~•`.'~..:,' - _
m,....... , _ , - ~
.r,. i-1 I ~I I I ~I I CI I ~ ~ =1 I ~ I I ~ I ~ . = =1 l~Tf~ 11=1 I I-1 I ~I~ I
. ~.~,m- w~~ - - '~If~ff I II~II~ _ _ ~II~Ii~ll~ll~ll~lll-II~II~ 1,. I II~II~iI~II~II~I~II~fbi-
~1~ I I~~I ~ ~~11~1 I ~I~II~II~II II~II~il~ll~ll~l ~-iI~III I T II~IIbII~~II~IHI~ I~I~~'
d _.ym . - s . 4° '~JI ~ I I I~~~II~~l~~lf~~ll~~II~~II~~rIP''
i ? ® jjf
..4.,,. A t w.e ~ ° i i y1v FIGURE 3 6°
F k ~„~,r~m„ , TOP OF BANK FIGURE 4
~ ~ ~ ' 1 ~ TERMINATION E%TEND 2-3' TERMINAL ANCHOR PAST TOP OF
- ~ ToP ~ SWALE TRENCH
RSA. SEE ~ BMP SWALE ~3 (60dr 1 O EDGE OF~.- NOTE 9. Lf ~ 0.0054~~/FT, ~ ~ F
Ru AY ~~tuN~ A 3 FT EvY°t(~1 WIDTH, / \ TERMINATION TRENCH (FlG. 4)
DEL - 154 25 ~ EL 156.11 ~ :1 SIDE SLOPES f . ~ ~ _ _ e
. ~ ,ls x .4 A _
_ - i - -
E. ~ _ _ _ I ~ t
MINIMUM OF 3° OVERLAP
CHECK SLOT (FlG. 2)
re
2~•Ti.. . > v . . ~ x ~c. „ .'x . v r +re . ~ .:a':. ;i~sst"r.~ - ~,s'.. o+. maX, ~ w3~i w -ms`s--3'+ ~sux _ ~ _ ~ F . ~v..,., _..w.:.~:
PERMANENT SEEDING.
NOTES: SEE SHEET C-18 F R EE ING GRAPHIC SCALE T~ OF BANK 3~, TERMINATION INITIAL ANCHOR
0 S D 1. NO ACTIVITY SHALL OCCUR CLOSER THAN 79' TO ANY ACTIVE TAXIWAY OR 150' TO ANY ACTIVE RUNWAY WITHOUT SCHEDULE.
COORDINATION WITH THE RPR, UNLESS OTHERWISE NOTED. 50 0 25 50 100 2~ (FlG. 3) ~ TRENCH (FIG. 1)
2. CONSTRUCTION ACTIVITY WITHIN THE TSA/OBSTACLE-FREE ZONE IS PERMISSIBLE WHEN THE TAXIWAY IS OPEN TO
AIRCRAFT TRAFFIC IF ADEQUATE WINGIIP CLEARANCE EXISTS BETWEEN THE AIRCRAFT AND EQUIPMENT/MATERIAL;
EXCAVATION, TRENCHES, OR OTHER CONDI110NS ARE CONSPICUOUSLY MARKED AND LIGHTED; AND LOCAL NOTAMS (IN F'E>;°P ARE IN EFFECT FOR THE ACTIVITY (SEE AC 150/5300-13 FOR WINGTIP CLEARANCE REQUIREMENTS.) THE NOTAM i inch = 50 ft.
SHOULD STATE THAT, "PERSONNEL AND EQUIPMENT ARE WORKING ADJACENT TO TAXIWAY "A"",
300' RUNWAY TO TAXIWAY DISTANCE BOTTOM OF
SWALE FIGURE 5
TRENCH AND CHECK
129' CONSERVATION EASEMENT 1MDTH SLOT LAYOUT
TIE TO EX. GROUND TIE TO EX. GROUND
AT 9:1 RUNWAY ELEV. _ TAXIWAY ELEV. = AT 12:1 36.75' 36.75' 156.51 INSTALLATION NOTES: PLACE 6" x 6° CHECK SLOTS AT 30'INTERVALS ALONG THE CHANNEL. SEE FIGURE
158.41 SITE PREPARATION 2.
24.25' 3' 24.25' 1' 24.25' 3' 24.25' GRADE AND COMPACT AREA. CUT 4" x 4n TRENCH ALONG TOP OF BANK FOR MAT TERMINATION. EXTEND MAT 2
TO 3 FEET RBOVE CREST IF POSSIBLE. SEE FIGURE 3.
y ~ `y 'd ~ ~y ~ REMOVE ALL ROCKS, CLODS, VEGETATION, AND OBSTRUCTIONS SO THAT MATTING
I--llhll~ll~l ~ - .,,11!~II~IIhil(-III- r=11 r--Iris Il,..lf C I_I I r--~ ~r_-I ~ I l t~ - WILL HAVE DIRECT CONTACT WITH THE SOIL, BEGINNING AT THE CENTER OF CHANNEL AT THE DOWNSTREAM END OF THE AREA TO BE LlNE6, PLACE THE END OF THE ROLL IN ANCHOR TRENCH AND SECURE WITH
PREPARE SEEDBED BY LOOSENING 3 TO 4 INCHES OF TOPSOEL ABOVE FINAL GRADE. U-SHAPED WIRE STAPLES 6R GEOTEXIILE PINS. SEE FIGURE 1.
_ _ DRAINAGE EASEMENT FREEBOARD ELEV. = 149.47 ' .10-1;R STORM _e . . ®~~~e~®~®. . APPLY ANY TREATMENT SUCH AS LIME OR FERTILIZERS TO THE SOIL IF NEEDED. PLACE ADJACENT ROLLS IN THE ANCHOR TRENCH WITH A MINIMUM OF 3" OVERLAP.
1.4T T "v°~~a,~ ELEV, = 148,97 0.9T 1.47
0.9 BOTTOM OF SWALE 1 ~ _ °~a".,.,~~.w~~°° _ " i` _ - I' 1 DO NOT MULCH AREAS WHERE MAT IS TO BE INSTALLED. SECURE WITH STAPLES OR GEOTEXTILE PINS, BACKFILL ANCHOR TRENCH, AND COMPACT SOIL.
ELEV. - 148 '~1=11=!!!~ t~ I~ r '11= I'1-`-+T1~1T,11 25 -1 f -r 25 SEEDING UNROLL MAT OVER COMPACTED ANCHOR TRENCH, STOP AT NEXT CHECK SLOT OR
TERMINAL ANCHOR.
46" MIN. TEMPORARY LINER 3 SEE C-18 FOR SEEDING REQUIREMENTS.
C-30A APPLY SEED TO SOIL BEFORE PLACING MATTING. UNROLL ADJACENT ROLLS IN SAME MANNER, WITH A MINIMUM OF 3" OF OVERLAP,
WHEN USING PERMANENT LINER, APPLY ADDITIONAL SEED AFTER INSTALLATION AND STAPLE AT 18" INTERVALS ALONG OVERLAP.
SEASONAL H{GH 12" TALL BERM WITH 25:1 WATER TABLE SIDE SLOPES; ELEV 149.00 FILL MAT WITH SOIL. FOLD AND SECURE MAT ROLLS TIGHTLY INTO CHECK SLOTS. LAY MAT IN CHECK
INS1 INSTALL MANHOLE INSTALLATION ON SIDE SLOPES OF GRASSED SWALES SLOT, FOLD BACK AGAINST ITSELF, ANCHOR THROUGH BOTH LAYERS, BACKFILL AND
RINE RING IN CONCRETE. COMPACT SOIL, CONTINUE ROLLING MAP UPSTREAM, SEE FIGURE 2.
SEE _ 1 BMP SWALE 3 CROSS SECTION A SEE SLAB NOTE 3. EXTEND MAT 6' OVER BEYOND SWALE BOTTOM ON SIDE SLOPE AND EXCAVATE A 12"
NOTE: LONGITUDINAL SLOPE - 0.54% d ° . Q: x 6°' TERMINAL ANCHOR TRENCH. SEE FIGURE 4. BEGIN NEW ROLLS IN CHECK SLOT, AND OVERLAP ENDS MINIMUM OF 1'.
C-3Q NTS ~ ' ° ° d a. 'n . •a` ANCHOR MAT IN TRENCH ON 1 FOOT SPACINGS, BACKFILL AND COMPACT SOIL. SEE FIGURE 4 FOR TERMINATION AT UPSTREAM END.
d. ° ~ < ° 4 a b.-~'!~. LAY MAT LOOSE TO ALLOW CONTACT WITH SOIL SEE FIGURE 5 FOR TRENCH AND CHECK SLOT LAYOUT.
} ° Pd. 6 MIN. d~ DO NOT STRETCH TIGHT. LINER MUST MEET OR EXCEED THE FOLLOIMNG REQUIREMENTS:
6° CEINCRETE TO WATER QUALITY BMP ~ - 1.
LEVEL SPREADER < ` Y - ° ° _ (GRASS SWALE #3) ~ g- `8 ~ . ANCHOR MAT USING U-SHAPED WIRE STAPLES OR GEOTEXTILE PINS. -MAXIMUM PERMISSIBLE SHORT-TERM (1/2 HR.) VELOCITY OF 5 FT/SEC
a a. ° LIP TD EXTEND A MINIMUM OF 18° ° _ - ° a INSTALLATION IN GRASSED SWALES
BELOW GRADE A ~ ~ ' A . ' S' y- 8. i•° < a a C °4° . -MAXIMUM PERMISSIBLE LONG-TERM (50 HRS.) VELOCITY 6F 3 FT/SEC
TAP EL = 150,25 ` - ` EXCAVATE INITIAL ANCHOR TRENCH 12"X6" ACROSS THE CHANNEL AT THE LOWER - END OF THE SWALE. 5EE FIGURE 1. -MAXIMUM PERMISSIBLE SHEAR STRESS OF 0.45 LB/FT2
"''"-~-OW V FLOW OPENING ° 9"
FLOW a4`... a a
„ 36" RGP 6 SECTION A-A INV. = 150. x-36" RGP INV. = 150.53
" ~i
- INV. = 149.60 6> 3 TEMPORARY LINER INSTALf~ ATION DETAIL
d C-30 NTS
° A .
T 3 CONCRETE FLOW SPLITTEI ~PLITTER
2 BETE LEVEL SPREADER TO WATER QUALITY BMP c-3o NTs
CONC (GRASS SWALE #3)
C-3o NTS PLAN VIEW
PROJECT MANAGER DRAWING SCALE 1001 PINNACLE POINT DRIVE RELEASED FOR DATE' Pg9fib Rgg
a Y• ®a 1 ADDED SHEET 1 14 09 CRT AS SHOWN SUITE 110 E RSA AE COLUMBIA, SC29223 APPROVALS 'SA AND CORPORATE HEAREA DEVELOPMENT BMP SWALE #3 GRADING AND C-30
PROJECT DATE ~e,.x ®'9 2 UPDATED SHEET FOR SWALE DESIGN 25 40 DRAWN BY WK r [phone] 3 ADDED FLOW SPUTTER AND UPDATED PLAN PER DWQ REVIEW 02 RWH NOV 2009 raw,
APPROVED BY PROJECT NUMBER BIDDING Em I - kdo N ;vlb KS 0 Erk 40 t
Office Locations: t JC DJK 80324.OO.CA CONSTRUCTION JOHNSTON COUNTY AIRPORT EROSION CONTROL
REV. N0. DESCRIPTION DATE RLE NAME PLOT DATE community infrastructure consultants North Carolina Georgia p ~/g /~~~e South Carolina Kentuck RECORD DWG. SMITHFIELD, NORTH CAROLINA
NC UMSE big, REVISIONS - fpp b®as ~sp,,j~
ffa~ranmatissau~60 ~,~V

~~1v
o~?~
~~W
H
+
~NN~ °-Wm
N8
} ~ZW
a ~ EXISTING sous TAXIWAY "A". ~ ~
k~ SEE NOTE 2.
m o
o~~
V1Ny 2 F ~ ~ PROPOSED 4 PROPOSED ~ . { : i ~
° ~ TEMPORARY -2 ~ TEMPORARY -I9 . ~ ; . ~ ~ ~
~ ~ ~ ROCK SEDIMENT ~ CHECK DAM
,s DIKE CHECK DAM (TYP)
f < 8MP SWALE (1231 1
°a~ LP ®0.0054 FT/FT, C-30B N r~~~ uw
~Y ; 3 FT BOTTOM WIDTH m ,Ym~„ _ ~ ~ nines ESQ .~.G.._ ._K., ,..N t.~ n. _ , ~ _ _ :~.,~w r~. ~ wr ~ ~,.V,. ~ . v .w~ . ~~,o,. ,~.u._, m,,,,... .w,, ~u ~
~W.ry, w..... S r tiw..~., ..k.,:.,~ r,M,.. uv.a..>. M:;~n ,..M,~ ~ M~ ._,....WO T,~v~ av~.. _..,w ,y.. ,r, ~ ~ gg d ~ , , e & R , r'~ i ,~:M, . _ . ...sx F ,_..m ~a~
,v.. ~.y ..r, .~n..
Z}' ~H ZQQ a m..m..o. ~ . .,m ,,,r ~ , rj
a w. r. - 1 K.,. ..,.mom.,„ ,,...,,..z.. - ti+.M+. _ s
3 ~ ~ ~
µ M1 g F f a ,,.~r~
55 3 ,~f t A ~ ~ ~ - ^ ..m v .nu " y~ ZZ 1 a Y } ~ a O~W 3..g 3 ~
'.F . ` s 6~ ~ r ~ - t i t s ~ ~ ~ n..~ , ~ ~ } u . ~ 1 a'~ . 'E ~
t r ~ ~ ~ "ems ~ 8 r g, , ' y M r rte., ,y ~
a j a?~ ~ ti - ti r.. x ~ ~ - a ?
rc~i~ ~ F Fri ~ ~ ~ ' t ; . a~ ~~t_ , r.,~ ` 4, , r «r
. E ~ ~ ~ x ~ u
1 t a r ~ 13 ~ ti~ - a , N i
s` ~ n ~w w~,. f ~r°" .,n,
7 9 ~ i` ~ `t'R, 3 ~ Zf t t i' s i#
IF ~I' 4 E j ~ f~ ~ 1 ~ e
g' i t 'Y - ) ' < c 3 j ,
u~ ~ ~ BMP SYdALE ~5 (1231 ~ ~ ~ LF ®0.0054 FT~FT, 3 C-308 sr f~ .F
J 1 w „n~ = FT BOTT~I WIDTH,
r 1 ~ nvm» . , n x ~ .~.w:.,25t.a SIDt.,,5L0~ES) ~
.n RJ 65" r r.,
t..: ~,r..sn v . , a.u.,-..a. w. f ..m... ~
EXISTING RSA. . ~ ~ REMOVE E~. -3~` . 'f'y ~r ~ 3 ~ ~ y DIA, R~
x ~ w-- ..m~... -
t ~ ,..,,REMOVE EX. ~2AlE ..,m,,.,. ~""m AND INLET BOX. ..,m,.., ~,v,.~' ,T.r
a PLt1G AND
' r~' ABAND REMOVE EX. K ....._...M AN 'CU ~ LVERT tJMITS OF H..,.~. ; .-REMOVE EX. ASPHALT AND ~M. _ ~_.P-
y , , . PROVIDE P0: , ..fA PROVIDE POSITIVE
D!STUiiVCE DRAINAGE:K~.~~ .M,_.. _F . rw. .~.w~... - DRAINAt~:K~ w 1:~~ ~
•W,, ~ s ~ ~ . F ~ ~ a x...,~ - - - - k , _ _ _ ~
~ ~ . . ~ - _ _ ~ _ _ _ . . _ ~ - .~.W.~ a _ n. - _ ~ _ _
_ . , L. .1 ` . ~
, . s 1
.,+.+n `ti-+~_..~.....~..s... . -3e ~c .x^ i..~„»wT ".vim ,U 9
e . x
i . ~ ~ a -
vv. u,,, ~ ~ `.,..c - a's.__ -.ww°uv..... &4 ...r.. t-.-a .~:la .t . c.. s ~ w ~+p ~a ni.S: ,m'~' ~ . .X
.,.5. , IkYG ..AYt. ~rrYww`~"m ,.z s' .w.. r.. n~
PERMANENT SEEDING. SEE NOTES: SHEET C-18 FOR SEEDING
SCHEDULE. 1. NO ACTIVITY SHALL OCCUR CLOSER THAN 79' TO ANY ACTIVE TAXIWAY OR 150' TO ANY ACTIVE RUNWAY WITHOUT
COORDINA110N tMTH THE RPR, UNLESS OTHERWISE NOTED. GRAPHIC SCALE
2. CONSTRUCTION ACTIVITY WITHIN THE TSA/OBSTACLE-FREE ZONE IS PERMISSIBLE WHEN THE TAXIWAY IS OPEN TO a ~ ~
AIRCRAFT TRAFFIC IF ADEQUATE WiNGTIP CLEARANCE EXISTS BETWEEN THE AIRCRAFT AND EQUIPMENT/MATERIAL;
EXCAVA110N, TRENCHES, OR OTHER CONDITIONS ARE CONSPICUOUSLY MARKED AND LIGHTED; AND LOCAL NOTAMS
ARE IN EFFECT FOR THE ACTIVITY (SEE AC 150/53D0-13 FOR tMNGTIP CLEARANCE REQUIREMENTS.) THE NOTAM SHOULD STATE THAT, "PERSONNEL AND EQUIPMENT ARE WORKING ADJACENT TO TAXIWAY "A'°'. (IN FEET )
1 inch = 50 ft
332' RUNWAY TO TAXIWP JWAY TO TAXIWAY DISTANCE
128' CONSERVATION EASE SERVATION EASEMENT WIDTH
TIE TO EX. TAXIWAY GROUND AT 18:1 36.50' TIE TO EX. RUNWAY ELEV. 36.5D' GROUND AT 23:1 .138
ELEV. = 136
24' 3' 24' 1' 1' 24' 3' 24'
_ y ~ y y ~ ~
_ ~r~~~~~ar_-lir_- - I-..,,~ ~Ir=III-,..1r_r_ ~111~I_If`I_II-f-I I~+irCl ~~~I11 ~~~_~~r--
. . DRAINAGE EASEME 2AINAOE EASEMENT FREEBOARD ELEV. = 133.46
10-YR STORM 0.96, 1.46'
1.46' 0.96' ~ ELEV. ~ = 132.96 BOTTOM OF SWALE 1 ~
ELEV. =.132 r _I _ ~~I-~-rr~ 1
IL-111--rIr-~-1~~lr, 25
17"
TEMPORARY LINER 3 C-30A
NOTE: LONGITUDINAL SLOPE = 0.54 SEASONAL HIGH _ 12" TALL BERM WITH 25:1
WATER TABLE SIDE SLOPES; ELEV 133.0
1 AMP SWALE 5 ALE 5 CROSS SECTION A
C-30~ NTS
° Apo PROJECT MANAGER DRAWING SCALE 1001 PINNACLE POINT DRIVE RELEASED FOR DA E B®~d ®®e
1 ADDED SHEET 1 11 O9 T AS SHOYM m~. E SUITE „oe®d~„9® RSA AN[ .SA AND CORPORA~RE HE AREA DEVELOPMENT gMP SWALE #5 GRADING AND L713D JOHNSTON COUNTY AIRPORT EROSION CONTROL SMIT
WK COLUMBIA, SC 29223 APPROVALS m g' 2 UPDATED SHEET FOR SWALE DESIGN 25 1O DRAWN BY PROJECT DATE RWH NOV 200 (803) 786_4261 AL ~ 3 UPDATED CROSS SECTION AND GRADING PLAN PER DWO 02 1 9
APPROVED BY PROJECT NUMBER BIDDING p a / L
DJK 80324A0.CA office Locations: CONSTRUCTION Ji
REV. N0, DESCRIPTION DATE FILE NAME PLOT DATE community infrastructure consultants North Carolina Georgia et rr A South Carolina Kentuck d ®~Q~ HFIELD, NORTH CAROLINA
REVISIONS _ RECORD DIMG.~~ 741 HQ LIMSE NO, F °dau: oe l 'glYrrBY.@a16Wlsa