SW8050801_CURRENT PERMIT_20050812

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

�QF \NA Michael F. Easley, Governor
-17
e �o G William G. Ross, Jr., Secretary
- North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E. Director
Division of Water Quality
August 12, 2005
Mr. Jon W. Rosborough
Airport Director
New Hanover County Airport
1740 Airport Blvd.
Wilmington, NC 28405
Subject: Stormwater Permit No. SW8 050801
Wilmington International Airport General Aviation Apron Expansion
Project served by an Offsite System
New Hanover County
Dear Mr. Rosborough:
The Wilmington Regional Office received a complete Stormwater Management Permit
Application for Wilmington International Airport General Aviation Apron Expansion on
August 5, 2005. Staff review of the plans and specifications has determined that the
project, as ppropposed, will comply with the Stormwater Regulations set forth in Title 15A
NCAC 2H.1000. We are forwarding Permit No. SW8 050801, dated August 12, 2005, for
the construction of the subject project.
This permit shall be effective from the date of issuance until August 12, 2015, and shall be
subject to the conditions and limitations as specified therein.
If any parts, requirements, or limitations contained in this permit are unacceptable, you
have the right to request an adjudicatory hearing upon written request within thirty (30
days following receipt of this permit. This request must be in the form of a written petition,
conforming to Chapter 150E of the North Carolina General Statutes, and filed with the
Office of Administrative Hearings, P.Q. Drawer 27447, Raleigh, NC 27611-7447. Unless
such demands are made this permit shall be final and binding.
If you have any questions, or need additional information concerning this matter, please
contact either Paul Bartlett or me at [phone].
Sincerely,
Edw rd`Beck
Regional Supervisor
Surface Water Protection Section
ENBlptb: S:1WQSISTORMWATIPERMIT1050801.
cc: Robert C. Williams, El, Talbert & Bright, Inc.
Tony Roberts, New Hanover County Building Inspections
Beth E. Wetherill, New Hanover County Engineering
Paul T. Bartlett, P.E.
Wilminggton Regional Office
Central Files
North Carolina Division of Water Quality 127 Cardinal Drive Extension Phone [phone] Customer Servicel-877-623-6748 One
Wilmington Regional Office Wilmington, NC 28405-3845 FAX [phone] Internet: h2o.enr.state.nc.us NortllCara/l/lna
An Equal OpportunitylA(firmative Action Employer — 50% Recycled/10% Post Consumer Paper Xatrrrally

State Stormwater Management Systems
Permit Number SW8 050801
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
STATE STORMWATER MANAGEMENT PERMIT
HIGH DENSITY DEVELOPMENT
SERVED BY AN OFF -SITE STORMWATER CONTROL
AND AN ALTERNATIVE CONTROL SYSTEM
In accordance with the provisions of Article 21 of Chapter 143, General Statutes of North
Carolina as amended, and other applicable Laws, Rules, and Regulations,
PERMISSION IS HEREBY GRANTED TO
Mr. Jon W. Rosborough and New Hanover County Airport Authority
Wilmington International Airport General Aviation Apron Expansion
New Hanover County
FOR THE
construction of impervious areas with runoff to be treated in an offsite permitted stormwater
facility and a Vortechs stormwater treatment system, in compliance with the provisions of
15A NCAC 2H .1000 (hereafter referred to as the "stormwater rules') and the approved
stormwater management plans and specifications and other supporting data as attached
and on file with and approved by the Division of Water Quality and considered a part of this
permit. The stormwater runoff from the site will be routed to a Vortechs Model No. 7000
and an extended dry detention basin, the latter currently operated and maintained by New
Hanover County Airport Authority under the terms and conditions set forth in Permit No.
SW8 050547.
This permit shall be effective from the date of issuance until August 12, 2015, and shall be
subject to the following specified conditions and limitations:
I. DESIGN STANDARDS
1. This permit is effective only with respect to the nature and volume of stormwater
described in the application and other supporting data.
2. The runoff associated with this project has been approved to be discharged into a
stormwater management system permitted under SW8 050547 and a Vortechs Model
No. 7000, as described in Sections 1.10 and 1.11 on page 3 of this permit.
3. The total built -upon area allotted by Stormwater Management Permit No. 050547, is
4,247,100 square feet. This project proposes 151,589 square feet.
4. Approved plans and specifications for this project are incorporated by reference and
are enforceable parts of the permit.
5. All stormwater collection and treatment systems must be located in either dedicated
common areas or recorded easements. The final plats for the project will be recorded
showing all such required easements, in accordance with the approved plans.
6. The runoff from the permitted built -upon area must be directed into the permitted
stormwater system.
Page 2 of 9

State Stormwater Management Systems
Permit Number SW8 050801
7. The Vortechs Stormwater Treatment unit must be designed, sized and installed per
Vortechs specifications to achieve a minimum 70% Net Annual TSS removal efficiency.
8. Quarterly monitoring of the outflow from the Vortechs Unit is required. See Section II of
this permit for specific monitoring requirements.
9. In the event that the Vortechs Unit fails to function as required, or to meet the 70% Net
Annual TSS removal efficiency minimum, the sytem shall be replaced by other
permittable stormwater management measures, such as a sand filter.
10. The following design criteria have been provided in the extended dry detention basin
and must be maintained at design conditions:
a. Drainage Area, acres: 150
Onsite, ft : 6,534,000
Offsite, ft2: None
b. Total Impervious Surfaces, ft2: 4,247,100
C. Design Storm, inches: 1.0
d. Basin Bottom Elevation, feet: 7 - 13
e. TSS removal efficiency: 50
(Required Additional BMP to be provided by tributary projects.)
f. Storage Elevation, FMSI_: 9.87
g. Storage Surface Area, ftz: 77,200
h. Permitted Detention Volume, ft3: 66,734
i. Sediment Storage Volume, ft3: 20,604
j. Seasonal High Water Table, FMSL: 6.0
k. Controlling Orifice: 8.0"0 pipe (3.75" 0 low flow)
I. Drawdown Time for 8.0"0 orifice, hrs: 48
M. Receiving Stream/River Basin: Smith Creek 1 Cape Fear
n. Stream Index Number: 18-74-63
o. Classification of Water Body: "C; Sw"
11. The following design criteria have been provided in the Vortechs Model 7000 and
must be maintained at design conditions:
a. Design Storm: 1"
b. Drainage Area, fz: _ 151,589
Onsite, ft : 151,589
Offsite, ft Z: 0
C. Total Impervious Surfaces, ft2: 151,589
d. Net Annual TSS Removal Efficiency: 70%
(followed by dry basin at 50% efficiency for combined 85% system efficiency)
e. Runoff Coefficient: 0.95
f. Grit Chamber Area, ft2.. 50.30
g. Flow Rate Capacity, cfs: 11,00
In. Design Ratio, DR: 29.5
(DR = (Tot. Drain Area) x (Runoff Coef.) x (cfs to gpm conversion)IGrit Chamber Area)
Page 3 of 9

State Stormwater Management Systems
Permit Number SW8 050801
II. MONITORING REQUIREMENTS
1. The permittee shall submit a monitoring plan to the DWQ for approval within 60 days of
receipt of this permit, for the Vortechs Unit.
2. Quarterly monitoring of both influent and effluent is required. Samples shall consist of a
grab sample of the first flush (within the first 15 minutes of discharge from the unit) and
flow -paced composite samples collected, at a minimum over the first three hours of the
event.
3. Samples must be collected in each of the four seasons. Monitoring parameters shall
include the following at a minimum. Additional parameters may be added on a case -by -
case basis, to address water quality issues in the area.
a. Total Suspended Solids
b. Oil and grease
C. TKN
d. Ammonia Nitrogen
e. Nitrate -Nitrite
f. Total Phosphorous
g. Total Coliform
h. ' Fecal Coliform
i. Enterococcus
i. Flow
4. The storm event date, total rainfall and duration must be recorded for both the storm
event prior to the sampled event and the sampled event.
5. All samples shall be collected from a representative storm event. A representative storm
event is an event that measures greater than 0.1 inches of rainfall and that is preceded
by at least 72 hours during which no storm event measuring greater than 0.1 inches has
occurred. A single storm event may contain up to 10 consecutive hours of no
precipitation. For example, if it rains for 2 hours without producing a collectible
discharge, and then stops, a sample may be collected if a rain producing discharge
begins again within the next 10 hours.
6. The permittee shall split samples with DWQ for at least two events during the first year
after the Vortechs unit is installed. The permittee shall notify the Division as soon as
possible of their intent to provide split samples .
7. Within 30 days of receiving laboratory results, the permittee shall submit copies to the
Division of Water Quality, Stormwater and General Permits Unit, 1617 Mail Service
Center, Raleigh, NC 27699-1617. All data submitted must reference the project name,
location and permit number.
8. The permittee may petition to have the monitoring requirements modified, reduced, or
eliminated only after 10 valid monitoring events for 10 different storm events have been
submitted for the system, during the course of a full year. Modification shall be
determined on a case -by -case basis.
9. An annual report shall be submitted by March 1 of each year. The report shall document
the inspection, maintenance, and monitoring activities performed during the previous
calendar year, and summarize overall system performance. The annual report shall be
submitted to NCDENR-DWQ, Stormwater and General Permits Unit, 1617 Mail Service
Center, Raleigh, NC 27699-1617.
Page 4 of 9

State Stormwater Management Systems
Permit Number SW8 050801
III. SCHEDULE OF COMPLIANCE
The offsite stormwater management system shall be constructed in its entirety,
vegetated and operational for its intended use prior to the construction of any built -
upon surface associated with this project.
2. During construction, erosion shall be kept to a minimum and any eroded areas of the
system will be repaired immediately.
3. The permittee is responsible for keeping the stormwater collection system on the lot
clear of debris, and keeping the site stabilized in accordance with the requirements of
the NC Erosion and Sediment Control Design Manual.
4. New Hanover County Airport Authority, shall, at all times, provide the operation and
maintenance necessary to assure the permitted stormwater management system
functions at optimum efficiency. The approved Operation and Maintenance Plan must
be followed in its entirety and maintenance must occur at the scheduled intervals
including, but not limited to:
a. Semiannual scheduled inspections (every 6 months).
b. Sediment removal.
C. Mowing and revegetation of side slopes.
d. Immediate repair of eroded areas.
e. Maintenance of side slopes in accordance with approved plans and
specifications.
f. Debris removal and unclogging of outlet structure, orifice device and catch basins
and piping.
g. Access to the outlet structure must be available at all times.
5. The permittee shall submit to the Director and shall have received approval for revised
plans, specifications, and calculations prior to construction, for any modification to the
approved plans, including, but not limited to, those listed below:
a. Any revision to the approved plans, regardless of size.
b. Project name change.
C. Transfer of ownership,
d. Redesign or addition to the approved amount of built -upon area.
e. Further subdivision, acquisition or selling of the project area. The project area is
defined as all pro erty owned by the permittee, for which Sedimentation and
Erosion Control flan approval or a CAMA Major permit was sought.
f. Filling in, altering, or piping of any vegetative conveyance shown on the
approved plan.
6. The Director may determine that other revisions to the project should require a
modification to the permit.
7. New Hanover County Airport Authority, must keep records of maintenance activities
and make them available upon request to authorized personnel of DWQ. The records
will indicate the date, activity, name of person performing the work and what actions
were taken.
8. This permit shall become voidable unless the facilities are constructed in accordance
with the conditions of this permit, the approved plans and specifications, and other
supporting data.
9. New Hanover County Airport Authority, is responsible for providing, prior to issuance
of a Certificate of Occupancy, and prior to operation of the permitted stormwater
management facility, a certification from an appropriate designer for the system
installed, certifying that the permitted facility has been installed in accordance with
Stormwater Permit No. SW8 050547, the approved plans and specifications, and other
supporting documentation. Any deviations from the approved plans and specifications
must be noted on the Certification.
Page 5 of 9

State Stormwater Management Systems
Permit Number SW8 050801
10. A cop of the approved plans and specifications shall be maintained on file by the
Permi tee for a minimum of ten years from the date of the completion of construction.
11. This lot is limited to the amount of built -upon area indicated in the supporting
calculations and per approved plans. The project must have a built -upon area less
than or equal to the amount permitted under tormwater Permit No. SW8 050547.
Additional built -upon area will require a modification to the overall Permit.
12. New Hanover County Airport Authority, must record any deed restrictions as required
by their permit, and they must verify that the proposed built -upon area does not
exceed the allowable built -upon area. Once the lot transfer is complete, the built -upon
area may not be revised without approval from the permittee, and responsibility for
meeting the built -upon area limit is transferred to the individual property owner.
13. The drainage features shown as a part of the stormwater management system on the
approved plan shall not be filled in, altered, or piped by any party without first
submitting a revision to the permit and receiving approval from the Division.
14. The Director may notify the permittee when the permitted site does not meet one or
more of the minimum requirements of the permit. Within the time frame specified in
the notice, the permittee shall submit a written time schedule to the Director for
modifying the site to meet minimum requirements. The permittee shall provide copies
of revised plans and certification in writing to the Director that the changes have been
made.
III. GENERAL CONDITIONS
This permit is not transferable except after notice to and approval b the Director. In
the event there is a desire for the facilities to change ownership, or here is a name
change of the Permittee, a formal permit request must be submitted to the Division of
Water Quality accompanied by an application fee, documentation from the parties
involved, and other supportingmaterials as may be appropriate. The approval of this
request will be considered on its merits and may or may not be approved. The
permittee is responsible for compliance with all terms and conditions of this permit
until such time as the Director approves the permit transfer.
2. Failure to abide by the conditions and limitations contained in this permit may subject
the Permittee to enforcement action by the Division of Water Quality, in accordance
with North Carolina General Statute 143-215.6A to 143-215.6C.
3. The issuance of this permit does not preclude the Permittee from complying with any
and all statutes, rules, regulations, or ordinances which may be imposed by other
government agencies (local, state, and federal) which have jurisdiction.
4. In the event that the offsite stormwater facilities fail to perform satisfactorily, including
the creation of nuisance conditions, New Hanover Count Airport Authority is
responsible for taking immediate corrective action, including those as may be required
by this Division, such as the construction of additional or replacement stormwater
management systems.
5. The permittee grants permission for DENR Staff to enter the property for the purpose
of inspecting afl components of the permitted stormwater management facility.
6. The permit may be modified, revoked and reissued or terminated for cause. The filing
of a request for a permit modification, revocation and reissuance or termination does
not stay any permit condition.
Page 6 of 9

State Stormwater Management Systems
Permit Number SW8 050801
7. The permittee shall notify the Division of any name, ownership or mailing address
changes within 30 days.
Permit issued this the 12th day of August 2005.
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
Clay Q
or Fatf W. Klimek, Director
Division of Water Quality
By Authority of the Environmental Management Commission
Page 7 of 9

State Stormwater Management Systems
Permit Number SW8 050801
Stormwater Project Number SW8 050801
Wilmington International Airport General Aviation Apron Expansion
New Hanover County
Designer's Certification
I, , as a duly registered in the State of
North Carolina, having been authorized to observe (periodically/ weekly/full time) the
construction of the project,
(Project)
for (Project Owner) hereby state that, to the
best of my abilities, due care and diligence was used in the observation of the project
construction such that the construction was observed to be built within substantial
compliance and intent of the approved plans and specifications.
Required Items to be checked for this certification to be considered complete are on page 2
of this form.
Noted deviations from approved plans and specifications:
Signature
Registration Number
Date
SEAL
Page 8of9

State Stormwater Management Systems
Permit Number SW8 050801
Certification Requirements:
1. The lot contains no more than the permitted amount of built -upon area.
2. All the built -upon area associated with the project is graded such that the
runoff drains to the system.
3. The lot has been stabilized with permanent vegetation to prevent erosion.
4. Vegetated slopes are no steeper than 3:1.
5. Roof drains are located such that building runoff drains into the systern.
6. The inlet from this project into the approved offsite system is located per the
approved plans and does not cause short-circuiting.
cc: NCDENR-DWQ
Tony Roberts, New Hanover County Building Inspections
Page 9 of 9

OFFICE USE ONLY
Date Received
Fee Paid
Permit Number
AUQ 2 I 2D DS
1 1
06O
05fo rM ` AZ4 �p "V �' 2' State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
This form may be photocopied for use as an original
I. GENERAL INFORMATION
1. Applicants name (specify the name of the corporation, individual, etc. who owns the project):
New Hanover C_o_unt.y Airport Au_th
2. Print Owner/Signing Official's name and title (person legally responsible for facility and compliance):
Jon W. Rosbor_Qu_gh_,... Airport __tjrecto_r
3. Mailing Address for person listed in item 2 above:
_J_7 4_0_Air_por�B I V d .
City: Wilmi _gton Stater Zip: 2.8A_05
Telephone Number: ( 910 341-4
4. Project Name (subdivision, facility, or establishment name - should be consistent with project name on plans,
specifications, letters, operation and maintenance agreements, etc.):
Wilmington International Aj~rport_Ce_nera. A'.-ka_t�n Apron
Expansion
5. Location of Project (street address):
City: —Wilmington County: New Hanover
6. Directions to project (from nearest major intersection):
_A - r_po r-t-81_vJ__tr i _ j=t.h-2.3_�5 tr_e
7. Latitude: 3 4 ° 16 ' 14 " N Longitude: 7 7 ° 5 4 ' 0 9 " W of project
8. Contact person who can answer questions about the project:
Name: Robert Williams Telephone Number: ( 910 ) 763-5350
Talbert & Bright, Inc. AND Julie Wilsey, Deputy Director
Wilmington International Airport
II, PERMIT INFORMATION: 910-341-4333 ext 1002
Specify whether project is (check one): X—New Renewal Modification
Refer to Master Plan Permit No. SW8 040836
Permit No. SW8 050547
Form SWU-101 Version 3.99 Page I of 4

2. If this application is being submitted as the result of a renewal or modification to an existing permit, list the
existing permit number . and its issue date (if known)
3. Specify the type of project (check one):
Low Density X High Density Redevelop General Permit Other
(Pocket)
4, Additional Project Requirements (check applicable blanks):
_CAMA Major Sedimentation/Erosion Control 404/401 Permit _NPDES Stormwater
Information on required state permits can be obtained by contacting the Customer Service Center at
1-877-623-6748.
III. PROJECT INFORMATION
1. In the space provided below, summarize how stormwater will be treated. Also attach a detailed narrative
(one to two pages) describing stormwater management for the project.
Stormwater wiII he treated with a Vortechnics Stormwater Treatment
System fora minimum of 70% TSS removal s1nd Extended _Dry Detention
Basin No. -..I fox' 50% TSS removal to meet the required 85% TSS removal.
2. Stormwater runoff from this project drains to the Cam Fear ^ River basin.
3. Total Project Area: 3 . 2 0 acres 4. Project Built Upon Area: 10 0' %
5.. How many drainage areas does the project have? 1
6. Complete the following information for each drainage area. If there are more than two drainage areas in the
project, attach an additional sheet with the information for each area provided in the same format as below.
�54S'�2CigL
,Basin
i In�Farfmaion :��.pr��"�
�+`'�+��Urarnage�,A�-.e�� l� ��,
�z?�'� D�au�-ag��Area 2•�h.��.. .,�.
Receiving Stream Name
Receiving Stream Class
Drainage Area
3.48 AC 151,589 SF
Existing Impervious* Area
2
Proposed Impervious*Area
3,48
% Impervious* Area (total)
100
_� ; _ Imgc�iw�ousSui f.a.'c,eA_rre.�
e
"Draiiia�Ee Area2,
On -site Buildings
On -site Streets
On -site Parking
On -site Sidewalks
Other on -site t e i
3.48 AC 151,589 SF
Off -site
Total: 1
Total:
* Impervious area is defined as the built upon area including, but not limited to, buildings, roads, parking areas,
sidewalks, gravel areas, etc.
Form swu-101 Version 3.99 Page 2 of 4

7. How was the off -site impervious area listed above derived
IV. DEED RESTRICTIONS AND PROTECTIVE COVENANTS
The following italicized deed restrictions and protective covenants are required to be recorded for all
subdivisions, outparcels and future development prior to the sale of any lot. If lot sizes vary significantly, a table
listing each lot number, size and the allowable built -upon area for each lot must be provided as an attachment.
I. The following covenants are intended to ensure ongoing compliance with state stormwater management permit number
N/A _ as issued by the Division of Water Quality. These covenants may not be
changed or deleted without the consent of the State.
2. No more than N/A square feet of any lot shall be covered by structures or impervious materials.
Impervious materials include asphalt, gravel, concrete, brick, stone, slate or similar material but do not include wood
decking or the water surface of swimming pools.
3. Swales shall not be filled in, piped, or altered except as necessary to provide driveway crossings.
4. Built -upon area in excess of the permitted amount requires a state stormwater management permit modification prior to
construction.
5. All permitted runoff from outparcels or future development shall be directed into the permitted stormwater control
system. These connections to the stormwater control system shall be performed in a manner that maintains the integrity
and performance of the system as permitted.
By your signature below, you certify that the recorded deed restrictions and protective covenants for this project
shall include all the applicable items required above, that the covenants will be binding on all parties and persons
claiming under them, that they will run with the land, that the required covenants cannot be changed or deleted
without concurrence from the State, and that they will be recorded prior to the sale of any lot.
V. SUPPLEMENT FORMS
The applicable state stormwater management permit supplement form(s) listed below must be submitted for each
BMP specified for this project. Contact the Stormwater and General Permits Unit at [phone] for the status
and availability of these forms.
Form SWU-102
Wet Detention Basin Supplement
Form SWU-103
Infiltration Basin Supplement
Form SWU-104
Low Density Supplement
Form SWU-105
Curb Outlet System Supplement
Form SWU-106
Off -Site System Supplement
Form SWU-107
Underground Infiltration Trench Supplement
Form SWU-108
Neuse River Basin Supplement
Form SWU-109
Innovative Best Management Practice Supplement
Form SWU-101 Version 3.99 Page 3 of

VI. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Water Quality (DWQ).
A complete package includes all of the items listed below. The complete application package should be
submitted to the appropriate DWQ Regional Office.
Please indicate that you have provided the following required information by initialing in the space provided
next to each item.
Initials
• Original and one copy of the Stormwater Management Permit Application Form ftLi
• One copy of the applicable Supplement Form(s) for each BMP 40
• Permit application processing fee of $420 (payable to NCDENR) QLw
• Detailed narrative description of stormwater treatment/management 9co
• Two copies of plans and specifications, including: gt'j
Development/Project name
Engineer and firm
-Legend
North arrow
- Scale
Revision number & date
Mean high water line
Dimensioned property/project boundary
- Location map with named streets or NCSR numbers
- Original contours, proposed contours, spot elevations, finished floor elevations
- Details of roads, drainage features, collection systems, and stormwater control measures
- Wetlands delineated, or a note on plans that none exist
Existing drainage (including off -site), drainage casements, pipe sizes, runoff calculations
- Drainage areas delineated
- Vegetated buffers (where required)
VII. AGENT AUTHORIZATION
If you wish to designate authority to another individual or firm so that they may provide information on your
behalf, please complete this section.
Robert C. Williams, Eli.
Designated agent (individual or firm): Talbert & Bright, Inc.
Mailing Address: 4 81 0Shellev Driv
C ity:_W..il mi.n.g t.o n
Phone: ( 910 ) 763-5350
VIII. APPLICANT'S CERTIFICATION
State: NC
2 84 05
Fax: ( 910 ) 762-6281
I, (print or type name ofperson listed in General information, item 2) Jon W. Rosborough
certify that the information included on this permit application form is, to the best of my knowledge, correct and
that the project will be constructed in conformance with the approved plans, that the required deed restrictions
and protective covenants will be recorded, an that the proposed project complies with the requirements of t5A
NCAC 21­1.1004-ti r I
Sig
Form SWU-101 Version 3.99 Page 4 of 4
Date: / /U

swg d 5-o 40oI
Wilmington International Airport
General Aviation Apron Expansion
Vortechs Storm►vater Treatment System
Operation and Maintenance Plan
The system shall be inspected monthly during the construction phase and for the first six
months after the project is complete and then quarterly thereafter. Additionally, the unit
shall be inspected after each storm event greater than F, and following major sediment
loading events such as oil/fuel spills, floods, etc. Inspections shall include a visual
observation of sediment accumulation, confinnation that the system is operating properly,
and removal of any accumulated trash, vegetation or debris.
2. The system shall be inspected during a representative storm event at least once per year
to verify the system is operating properly.
3. A system inspection shall be performed concurrently with each monitoring event.
4. All inspections and maintenance activities shall be documented using a standardized form
which is used for each visit.
5. Maintenance shall be performed in accordance with the manufacturer's recommendations
unless otherwise specified in the PEP document.
b. Sediment shall be removed, at a minimurn, annually and when the top of the sediment
pile is approximately one foot below the dry weather water level. The depth of the unit
can be measured without any entry into the unit via a dipstick. The dry weather water
level is the level at which the water is retained in the unit and will not flow out over the
lowest weir plate.
7. Oil levels greater than 1.0 inch shall be removed immediately by a licensed waste
management firm. The oil accumulation can be detennined using a conventional dipstick
tube.
8. During each inspection or monitoring visit, any accumulated trash, vegetation or debris
should be removed and properly disposed.
9. Monitoring will be accomplished in accordance with the permit conditions.

I acknowledge and agree by my signature below that I am responsible for the performance of the
nine maintenance procedures listed above. I agree to notify NCDENR-DWQ of any problems
with the system or prior to any changes to the system or responsible party.
Name: Jon W. Rosborough
Title: . Airport Director
Address: 1740 Airport Blvd., Wilmington, NC 28405
Phone
Signa
Date:
I, J- ," : " I- J is m R—S_ , a Notary Public of the County of A/e-w pia oOOO—,r—
State of North Carolina, hereby certify that appeared
personally before me this day and being duly sworn acknowledged thatAhe above form was
executed by him.
Witness my hand and notarial seal, this day of jquQo,St, 2005
otary ro
My commission expires c S! o j a oc>3 _
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Vortechs° Stormwater Treatment System
INSPECTION & MAINTENANCE LOG
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1. The water depth to sediment is determined by taking two measurements with a stadia rod: one measurement from the
manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. When the
difference between the two measurements is six inches (152 mm) or less, the System should be cleaned out.
2. For optimum performance, the System should be cleaned out when the floating hydrocarbon layer accumulates to an
appreciable thickness. in the event of a spill, the System should be cleaned immediately.
Rev 4-29-04 (WSG)

Per.-- •} No. Sy1 c6
(To be provided by DWQ)
State of North Carolina
Department of Environment and Natural Resources
Division of Water Quality
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
EXTENDED DRY DETENTION BASIN SUPPLEMENT
This form may be photocopied for use as art original.
DWQ Storrnwater Management Plan Review:
A complete storrm.i,ater management plan submittal includes a dry detention basin supplement for each basin,
design calculations, plans and specification showing all basin and outlet structure details, and a fully executed
operation and maintenance agreement.
I... . PROJECT INFORMATION (Please complete the following information):
Project Name: w; 3 mi ngton Intern ationaI Ai,r_port- (.1,-tprmwatPr M,9nagemPnfi-Pha.-' 1 )
Contact Person: Fric- M,,_ srirmp, P.E_ Phone Number: 910-763-5350
For projects with multiple basins, specify which basin this worksheet applies to:Extended Dry; )Detention
Design Stonnm: (Please mark one) ❑1 yr, 24 hr storm fh" storBasin No. 1.
150 acres C'
Drainage Area: 6, 5 3 4, 0 0 0 square feet
1" R infall Runoff
Require Volume: 94 , 525 cubic feet
:1 (A-1)
Basin Dimensions: F;( Irregular Shape)
Built -upon Area: 4 , 2 4 7 . 100 square feet
SHWT elevation:
FMSL
Bottom Elevation: 7 tt o 13feet, M SL Area: 110 0 fl long x 3 5 0 ft wide = 3 85, 000 ft2 (A - 4 2)
Storage Elevation: g_ 8 7 feet, MSL Area: 10 0 0 ft Tong x 7 7. 2 fI «side= 77,200 ft2 (A- 4 2)
(A-3)
Detention Volume Provided: 66,734 cubic feet ( Peak Storage, Routed 1" Rainfall)
Sediment Storage Provided: 2 0 .6 04A- 3) cubic feet (Equivalent to 20% of the detention volume)
Sediment Storage Elevation: 10. 1 (A-3) S FMSL
Drawdown Orifice: ';3 . 7 5 "d IN 8 " PVC (Please indicate size and type of orifice)
Required Additional IMP to achieve a total of 85% TSS (check one):
❑Grassed swale ❑Vegetated Filter ® Other To .be provided by tributary
projects.
(A-1) -'Denotes Stormwater Management Narrative and
Computations, Appendix A, Page A-1.

r. (To be provided by DH' J)
II, REQUIRED ITEMS CHECKLIST
The following checklist outlines design requirements per the Stormwater Best Management Practices Manual
C. Department of Environment, Health, and Natural Resources, November, 1995) and Administrative
Section 15A NCAC 211.1008.
Initial in the space provided to indicate the following design requirements have been met and supporting
documentation is attached. If the applicant has designated an agent in the Stormwater Management Permit
Application Form, the,agent may initial below. If a requirement has not been met, attach written
justification.
Please initial in the blanks prior to each requirement.
a. The basin captures the runoff from the 1 year, 24 hour storm and releases it over a period of 48
hours
OR the basin captures the runoff from the I inch storm and allows it to draw down over a period
of 2-5 days.
C. The miniiiium flow length ratio is 3:1, L:W.
d. Basin sideslopes are no steeper than 3:1.
NA e. A small permanent pool has been provided at the outlet to reduce clogging. Inconsistent with
FAA wildlife
�. f. Cleanout access has been provided, sufficient for heavy equipment. Hazards Advisory
Circular
A,drain has been provided which will completely empty the basin for cleanout.
Suffrcient'volume has been provided for any local government peak flow requirements.
i. If the basin was used during construction as a sediment basin or trap, it must be cleaned out to
design specifications prior to operation as a dry detention basin.
�. A vegetation plan has been prepared by a N.C. licensed professional. Consideration must be
given to the grasses specified due to the frequent inundation.
k. The basin `must be stabilized within 14 days of construction.
The design }provides for the sediment storage in addition to the detention volume that is equal to
20% of the detention volume.
in. Inlet and outlet channels have been protected from scour during high flows from large storms.
ten. In areas of easily erodible soils, an additional plunge pool at the inlet has been provided, or riprap
is used as an energy dissipator.
-1 o. A forebay"to capture sediment is recommended to make ceanout easier.
The basin, is located in uncompacted natural soils.
The seasdjal high water table is located at least I foot below the bottom of the extended dry
detention basin.
NA r. An additional BMP (such as a Swale or vegetated filter) has been designed to operate in
conjunction with this dry detention basin to meet the required minimum 85% TSS removal.
REQUIRIMENT FOR TRIBUTARY PROJECTS.

Pei No
. (To be provided by DYVQ)
f
I1I. EXTENDED DRY DETENTION OPERATION AND MAINTENANCE AGREEMENT
The extended dry det6tion system is defined as the dry detention basin, forebay, and the required additional
BMP.
This system (check one) ❑ does ® does not, incorporate a vegetated filter.
This system (check one) Udoes ❑ does not incorporate non-integrated pretreatment.
Maintenance activities shall be performed as follows:
1. All grassed areas of the basin shall be mowed at least twice annually, more frequently as needed.
2. Debris must be removed from the basin, outlet and orifice whenever it accumulates or at least twice
annually.
3. Annually- inspect the basin after a rain event to ensure it is functioning properly.
4. Repair any erosion of the side slopes and around the inlets and outlet, immediately.
5. Accumulated sediment shall removed if it has reduced the available volume to 75% of the original
depth.
b. The emergency`spiIlway shall be kept in good working order.
7. Woody vegetation shall be removed from the banks.
8. Any areas of the system found to be deficient shall be repaired or replaced to design standards.
9. Written records of the inspections and maintenance activities shall be kept on file.
I acknowledge and agree by my signature below that I am responsible for the performance of the above
maintenance procedures for the dry detention basin. I agree to notify DWQ of any problems with the system
or changes in the name of the project, responsible party, or address.
Print name: Jon W::: Rnshorough Title: Airport Director
Address: 1740 A; rznnrt- Rl ud _ Wi ] m; nat-nn . NC 28405
Phone:
Signature:
I,
a Notary Public for the State of
o �" , County of or-N S ha w ,
do hereby certify that To, Ws personally appeared before me this
the 2t7 }� day of _ lam( )-C, S` , and acknowledge the due execution
of the forgoing dry detention basin maintenance requirements. Witness my hand and official seal,
�sSA J�5
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koze
Signature /�0
My Commission expires
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