SW8040836_Historical File_20140611

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NCDENR
North Carolina Department of Environment and Natural Resources
Pat McCrory
Governor
June 11, 2014
Julie Wilsey, Deputy Airport Director
New Hanover County Airport Authority
1740 Airport Boulevard
Wilmington, NC 28405
Subject: Approved Plan Revision
Wilmington International Airport
Runway 24 Wildlife Hazard and NAVAID Critical Area Mitigation
Stormwater Permit No. SW8 040836
New Hanover County
Dear Ms. Wilsey:
John E. Skvarla, III
Secretary
On June 5, 2014, the Wilmington Regional Office received a request to revise the approved plans for the subject
project under Stormwater Management Permit Number SW8 040836. The revisions include the following:
1. The piping of an existing ditch at the end of Runway 24 in the designated "Low Density" area of the
Airport. The ditch carries mainly offsite runoff through the Airport property, and has been approved by the
Division of Water Resources to be filled and piped.
2. Sheet flow of the runway runoff through grassed areas is maintained or improved prior to entering the
piped system via inlets.
3. No built -upon area is proposed as part of this project. An extension of Runway 24 is part of the Airport's
20-year plan, however, that review will take place in the future under the rules in place at that time.
It has been determined that a formal permit modification is not required for the proposed changes. We are
forwarding you an approved copy of the revised plans for your files. Please add the attached plans to the
previously approved plan set.
Please be aware that all terms and conditions of the permit issued on November 19, 2004, and all of the
previously approved plan revisions, remain in full force and effect. Please also understand that the approval of
this revision to the approved plans for the subject State Stormwater Permit is done on a case -by -case basis.
Any other changes to this project must be approved through this Office prior to construction. The issuance of
this plan revision does not preclude the permittee from complying with all other applicable statutes, rules,
regulations or ordinances which may have jurisdiction over the proposed activity, and obtaining a permit or
approval prior to construction.
If you have any questions concerning this matter, please do not hesitate to call me at [phone].
Sincerely,
Linda Lewis
Environmental Engineer III
VGDS1arl: G:1WQ1SharedlStormwater1Permits & Projects120041040836 HD12014 06 permit-pr 040836
cc: Robin Austin, P.E., Talbert & Bright
New Hanover County Building Inspections
Wilmington Regional Office Stormwater File
Division of Energy, Mineral, and Land Resources
Land Quality Section - Wilmington Regional Office
127 Cardinal Drive Extension, Wilmington, North Carolina 28405 • [phone] / Fax: [phone]

Permit #
Date
Proiect name
SW8 040836
11/24/2004
Master
SW8 040918
11/24/2004
Perimeter Road Ph.1
SW8 040926
10/15/2004
GA Apron Rehab
SW8 991003
12/30/2004
T-Hangars
SW8050547
6/15/2005
EDDB#1
SW8050801
8/12/2005
GA Apron Expansion
SW8060326
4/7/2006
Air Wilmington
SW8 060425
4/27/2006
Runway 6-24 Rehab
SW8 060515
5/18/2006
Terminal Parking Lots
SW8 040836
8/31/2006
Runway 6-241LS
SW8 040918
7/18/2007
Perimeter Road Ph. II
SW8 060515
5/14/2008
Credit Card Parking Lots
SW8 040836
12/19/2008
Temporary Concrete Batch Plant
5W8 050547
10/28/2009
EDDB #1 Expansion
SW8 040836
7/12/2010
35 MALSR Catwalk, 35 ILS, 6-24 PAPIS
SW8 040836
3/29/2011
Taxiway A, D, F and H Rehab
SW8 040836
1/9/2011
Remove Temp. Conc. Batch Plant
SW8 040836
12/9/2011
Taxiway B, C, J and G paved shoulders
SW8 040836
7/23/2012
Runway 17 and Taxiway A Extension
SW8 040836
8/6/2012
Security Fencing
SW8 040836
10/4/2012
Air Wilmington Hangar No. 3
SW8 040836
6/11/2014
Runway 24 Wildlife Hazard & NAVAID
Master Plan
EDDB #1
BUA Added Cumulative
BUA Added
Cumulative
260.6
2
262.6
0
262.6
0.38
262.98
0
262.98
1.45
264.43
151589
151589
4.52
268.95
196725
348314
0
268.95
0
348314
4.63
273.58
201655
549969
1.56
275.14
0
549969
4.08
279.22
0
549969
5.18
284.4
225722
775691
0.85
285.25
0
775691
0
285.25
0
775691
-0.11
285.14
0
775691
-0.31
284.83
0
775691
-0.85
283.98
0
775691
7.74
291.72
0
775691
2.12
293.84
0
775691
0
293.84
0
775691
0.41
294.25
0
775691
0
294.25
775691
294.25
775691

Date Received Fee Paid express only) Permit Number
State of North Carolina
Department of Environment and Natural Resources
Division of Energy, Mineral and Land Resources
STORMWATER MANAGEMENT PERMIT PLAN REVISION APPLICATION FORM
This form may be photocopied for use as an original
I. GENERAL INFORMATION
1. Stormwater Management Permit Number: SW8 040836
2. Project Name: Runway 24 Wildlife Hazard and NAVAID Critical Area Mitigation
3. Permit Holder's name (specify the name of the corporation, individual, etc.):
Wilmington International Airport
4. Print Owner/Signing Official's name and title (person legally responsible for permit):
Tulie Wilsey
5. Mailing Address for person listed in item 2 above:
1740 Airport Blvd.
City: Wilmington State:NC Zip:28405
Phone: [phone]
Email:[e-mail]
II. PLAN REVISION INFORMATION
Fax: (910 ) 341-4365
1. Summarize the plan revision proposed (attach additional pages if needed):
The proposed project will convert an existing open channel network to a pipe network and includes grading
improvements totaling approximately 70 acres The purpose of the project is to mitigate wildlife attraction
and NAVAID critical area hazards posed by the existing channel network and grade irregularities in order to
enhance aviation safety at a regional transportation facility that encompasses 1,620.8 acres
III. SUBMITTAL REQUIREMENTS
Only complete application packages will be accepted and reviewed by the Division of Energy, Mineral and
Land Resources (DEMLR). A complete package includes all of the items listed below. The complete
application package should be submitted to the DEMLR Office that issued the permit.
1. Please indicate that you have provided the following required information by initialing in the space provided
next to each item.
if
• Original & 1 copy of the Plan Revision Application Form
• Two (2) copies of revised plans (must be revisions of original approved plan sheet(s))
• Application fee of $500.00 (made payable to NCD
VI. APPLICANT'S CERTIFICATION
� ,vED
JUN052014
Plan Revision Form Rev. Oct. 31., 2013

I,. (gInt or type name of person listed in General Information, item 3) Julie Wilsey
certify that I ve authorized these plan revisions and that the information included on this plan revision
application ' , t best o my knowledge, correct and complete.
1&
Signature: Date:
03-1A
Plan Revision Form Rev. Oct. 31, 2013

TALBERT & BRIGHT, INC.
ENGINEERING & PLANNING CONSULTANTS
LETTER OF TRANSMITTAL
To: NC Division of Water Quality
127 Cardinal Drive Ext
Wilmington, NC 28405
Date: 6/5114 Pro'. No. 3301-1003
Attention: Linda Lewis
Re: Wilmington International Airport
Runway 24 Wildlife Hazard & NAVAID
Critical Area Mitigation
WE ARE SENDING YOU:
®
Attached
❑
Under Separate Cover via
❑ Shop Drawings
❑
Prints
®
Plans
❑ Copy of Letter
❑
Change Order
❑
Other
_ the following items:
❑ Specifications
ITEM
DATE
NO.
DESCRIPTION
6/3/14
1
Plan Revision Application Form no fee
3/13/14
2
Two Copies of Plan Sheet G1
THESE ARE TRANSMITTED, as checked below:
®
For Approval
❑
®
For your Use
❑
❑
For Review and Comment
❑
❑
As Requested
❑
❑
FOR BIDS DUE ON
REMARKS
No Exception taken ❑ Resubmit _ Copies for Approval
Make Corrections Noted ❑ Submit Copies for Distribution
Amend and Resubmit ❑ Return Corrected Prints
Rejected — See Remarks ❑ Prints Returned After Loan to Us
❑ Other
COPY TO Project File SIGNED
Robin Austin
`mod ✓T�-1�1fL DN �(5� 1
ENGINEERING & PLANNING CONSULTANTS
4810 Shelley Drive Wilmington, NC 28405 910.763.5350 FAX [phone]

Lewis,Linda
From: Lewis,Linda
Sent: Wednesday, June 04, 2014 9:43 AM
To: Jeremy Schmidt. [e-mail])
Subject: Cape Island SW8 96031.9
Mr. Schmidt:
There is one alternative that you and I did not discuss. Right now, the proposed solution for handling the BUA overage
on the clubhouse lot is to reduce the BUA allocation for the Ocean Access Area from 10,000 sf down to 6770 sf. If the
membership feels that they can offer an alternate solution that will better serve the needs of the membership, then the
HOA could sign off on the request to transfer the permit and accept it "as is". However, if you do that, all of the
responsibility for resolving the BUA overage issue would fall to the HOA.
Mr. Mantooth has been working diligently to resolve the problem for you at his expense. He chose the path of least
resistance to get it done, thinking of the time that might be saved by doing so. Rather than getting everyone in an uproar
by asking each lot owner to give up some of their lot BUA allocation, Mr. Mantooth decided that taking BUA from the
Ocean Access Park would be an easier pill to swallow. From a compliance standpoint, I stand ready to approve the
revised plans which account for all of the clubhouse BUA. Unless you advise me that the HOA will accept the permit "as
is" and propose their own solution for compliance, I stand ready to transfer the permit to the HOA once the plan
revision is approved and the project is deemed compliant.
Linda Lewis
Environmental Engineer III
Division of Energy, Mineral and Land Resources
Wilmington Regional Office
127 Cardinal Drive Ext.
Wilmington, NC 28405
Main Office - 910-796-7215
Direct Line - 910-796-7343
E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to
third parties.

Lewis,Linda sN ,? 04093(a �
From:
Lewis,Linda
Sent:
Friday, May 30, 2014 9.44 AM
To:
Bennett, Bradley; Randall, Mike
Cc:
Sams, Dan; Vinson, Toby; Scott, Georgette
Subject:
RE: Project at Wilmington Airport
The airport currently holds a high density permit from the Division (SW8 040836) which designates the overall low
density status of the airport with areas of higher density that are treated with BMP's which do not promote standing
water. The piping of the stream is within the low density area of'the airport. The plan revision request was received on
February 14, 2014 and reviewed on March 21, 2014. The project proposed to pipe a stream at the end of Runway 24 in
the designated "Low Density" area of the airport.
The initial application letter from Robin Austin with Talbert & Bright requested an exemption from the stormwater rules
for the piping of the stream. A 401 certification was issued (SAW-2011-00455). Additional information was requested on
March 24, 2014, indicating that we were worried about how the piping of the stream might have an impact on
implementing the Airport Session Law which requires sheet flow through vegetated areas and buffers. After discussion
with Mike Randall, Ms. Austin and I agreed that the Session Law would not apply because no new impervious area is
being proposed as part of this piping project.
Once that determination was made, it became a matter of figuring out how piping of the stream would affect the low
density status of the airport, which only allows minimal piping under driveways to provide access and under built -upon
area such as a road, to facilitate drainage. On April 9, 2014,1 proposed to Ms. Austin that the existing permit be modified
to add a new BMP to treat that runoff. Ms. Austin replied on May 22, 2014 and requested a meeting to discuss the
particulars of how to accomplish that modification. I was getting ready to go on vacation and suggested that I could
meet with her after the Memorial Day holiday, but if she just had generic questions about modifying a permit, she could
speak to anyone in the group.
I will be calling Ms. Austin today to schedule that meeting for next week.
Linda 2
-----Original Message----- Ve\
From: Bennett, Bradley
Sent: Friday, May 30, 2014 7:26 AM
To: Randall, Mike; Lewis,Linda
Cc: Sams, Dan; Vinson, Toby
Subject. FW: Project at Wilmington Airport
Mike, Linda,
Can you give me information on this one so we can respond to Tracy. From what I recall I think this one has been
required to meet the high density requirements because of the piped conveyance system which moves it away from the
low density approach.
BB
Bradley Bennett
Stormwater Permitting Program Phone: [phone]

NC Division of Energy, Mineral and Land Resources Fax: [phone]
1612 Mail Service Center Email: bradlev.bennett ncdenr.sov
Raleigh, NC 27699-1612 Web: http://portal.ncdenr.org/web/ir/stormwater
Email correspondence to and from this address may be subject to public records laws
-----Original Message -----
From: Davis, Tracy
Sent: Thursday, May 29, 201410:15 PM
To: Vinson, Toby; Bennett, Bradley; Sams, Dan
Subject: Project at Wilmington Airport
Mitch asked me for an update on a project at the Wilmington airport where culverts are being placed in drainage ditches
from the 1940s that have triggered high density stormwater requirements. He wanted to know if this was true, if this is
required by federal NPDES rules or state statutes/rules (and if so, the citations). He said Mike Randall and Linda Lewis
have been working on this and asked if there are any alternatives or flexibility in this situation.
Please let me know so I can pass the information along to Mitch.
Thanks, Tracy
Tracy E. Davis, PE, CPM
Director - Division of Energy, Mineral, and Land Resources NC Dept. of Environment and Natural Resources
[e-mail]
[phone]
Email correspondence to and from this address may be subject to the NC Public Records Law and may be disclosed to
third parties.

Lewis,Linda
From:
Randall, Mike
Sent:
Tuesday, May 13, 2014 8:59 AM
To:
Lewis,Linda; Bennett, Bradley
Cc:
Scott, Georgette
Subject:
RE: ILM 3301-1003
The low density permit remains in effect unless the airport wants to modify it. I suppose they could request a
modification to have portions of the airport "deemed permitted." My understanding is that a lot of the airport is piped
and therefore would not be deemed permitted.
I concur that the piping of a natural stream is not an activity that would be allowed under the low density permit — nor
would we consider an "alternative practice" that could be used under the SL to eliminate standing water.
Mike
From: Lewis,Linda
Sent: Monday, May 12, 2014 3:22 PM
To: Randall, Mike; Bennett, Bradley
Cc: Scott, Georgette
Subject: RE: ILM 3301-1003
Mike- Thank you SO VERY much for all of this information. It is most helpful.
In regard to your question, which I highlighted in yellow below, the entire airport property was used to demonstrate low
density in 2004 for the Airport's existing permit. The SL for "deemed permitted" didn't exist at the time, so there is no
part of the existing construction or any of the subsequent proposed construction that has been "deemed
permitted". The airport's permit defines those areas that are low density and those areas which are high density and
require treatment. The session law was not clear about how to handle modifications to existing low density airport
permits and the impact of "deemed permitted" to existing low density development. Does the low density permit just
go away and get replaced by a "deemed permitted" decision?
The low density areas of the Wilmington airport are mostly the "landside" operations including the runways. Except for
those collected areas of the airport that were existing prior to the issuance of the permit, the landside operations are
currently permitted to utilize sheet flow to promote infiltration, grassed swales and buffers, as part of the low density
requirements of the permit. These are the same techniques that are utilized under the session law, but were not
"deemed permitted" at the time because they were built before the SL and under the low density permit.
The existing approved plans shows the area in question, at the end of one of the runways. There is an existing natural
stream which feeds Smith Creek about 1000 feet from the end of the runway. Between this stream and the runway, is
grass. The runoff currently sheet flows off the runway, across that 1000 feet of grass and into the natural stream.
Robin's proposal is to pipe the stream, not the runoff from the runway. The runoff from the runway will continue to
sheet flow over 1000 feet of grassed area, but instead of ending up in a natural stream, it will end up in a drop inlet and
pipe. While this may be a "deemed permitted" activity under the Session Law, the piping of a natural stream is not an
activity that is allowed under the low density permit, per the previously referenced Section 1.12 of the permit.
Linda

Lewis,Linda
From:
Randall, Mike
Sent:
Saturday, May 03, 201412:08 PM
To:
Lewis,Linda
Cc:
Bennett, Bradley, Scott, Georgette
Subject:
RE: ILM 3301-1003
Robin - I sent you a request for a State Stormwater Exemption on 2/11/2014 for the Wilmington International Airport
Runway 24 Wildlife & NAVAID Critical Area Mitigation project. What is the status of your review of that request? Please
let me know.
Linda- I'm trying to determine if the proposed project meets the session law requirements to be "deemed permitted.".
I've had to enlist some help from the central office. The Session law requires the runoff from runways and taxiways to
sheet flow through vegetated areas and buffers. I'm worried about the proposed collection system and how that
impacts the sheet flow requirement.
Robin -Does this apply even if there is no new impervious being created?
Comment:
SO 229 directs DENR to "accept alternative measures of stormwater control at public airports." Further "In accordance
with the Federal Aviation Administration August 28, 2007, Advisory Circular No. 15015200-338 (Hazardous Wildlife
Attractants on or Near Airports), the Department shall not require the use of stormwater retention ponds,
stormwater detention ponds, or any other stormwater control measure that promotes standing water. Also, "the
Department shall deem runways, taxiways, and any other areas that provide for overland stormwater flow that
promote infiltration and treatment of stormwater into grassed buffers, shoulders, and grass swales permitted
pursuant to the State post -construction stormwater requirements."
Does this apply even if there is no new impervious being created? Whether or not there is new impervious being
created, the Department shall not require the use of stormwater retention ponds, stormwater detention ponds, or
any other stormwater control measure that promotes standing water. S8 229 clearly directs DENR to accept
alternative measures of stormwater control.
Linda - I think that the proposed project is changing the previously "deemed permitted" runway by virtue of adding the
piped system. It would seem to me that if the runway was deemed permitted because of the sheet flow that its runoff
received, then anything that proposes to change that sheet flow to piping should be evaluated. I'm trying to figure out if
the proposed project impacts the current deemed permitted status going forward, and if it does, what to do about it.
Robin — I disagree that it changes the previously deemed permitted runway by adding the piped system. Runoff from the
runway will continue to sheet flow across the grass (approx. 1050 ft) and will enter the new piped system, just as it
entered the existing stream. There is no change to the sheet flow with this project. The stream is channelized flow, and
the pipe will be channelized flow as well. There is no sheet flow occurring in the stream.
Robin
Comment
I agree with Linda, the proposed project is changing the previously "deemed permitted" runway by virtue of adding the
piped system - the "Department shall deem runways, taxiways, and any other areas that provide for overland

stormwater flow that promote infiltration and treatment of stormwater into grassed buffers, shoulders, and grass
swales permitted"
Robin —OK, please keep me posted. I also wanted to add that if you look at plan I sent you, we are actually increasing the
length of sheet flow for the runoff coming from the runway.
Question
Is Robin suggesting that the airport is providing overland stormwater flow from the runway that promote infiltration
and treatment of stormwater into grassed buffers, shoulders, and grass swales permitted or is the airport piping the
runoff?
Linda- Only new development projects at airports are deemed permitted if they meet the requirements of the Session
Law for sheet flow. Since the construction of new impervious area is not part of this drainage project, the deemed
permitted aspect of the Session Law does not apply. However, the designated low density areas of the airport are still
subject to the master plan permit SW8 040836, issued on November 24, 2004. Per Section 1.12 of that permit: "Projects
submitted for approval under the low density option must demonstrate compliance with the low density criteria
described in the latest version of the stormwater rules. Projects that have clustered built -upon area, collection systems,
or which do not provide for sheet flow across at least 30' of grassed area will be considered high density." And per
Section 11.9 of that permit "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 stormwater plans,
including, but not limited to, 1) Any revision to any item shown on the approved plans, including the stormwater
management measures, built -upon area, details, etc., that has an impact on the permitted stormwater facility. 2) Project
name change 3) Transfer of ownership 4) Redesign or addition to the approved amount of built -upon area or to the
drainage area, 5) Further subdivision, acquisition, lease or sale of all or part of the project area. The project area is
defined as all property owned by the permittee, for which Sedimentation and Erosion Control Plan approval or a CAMA
Major permit was sought, and 6) Filling in, altering, or piping of any vegetative conveyance shown on the approved
plan." The proposed piping of that existing vegetated conveyance will not meet the low density criteria, which allows
only minimal piping to convey runoff beneath an impervious surface or to provide access to a lot. Additionally, the
County may want to weigh in on the increased runoff volume and flow rate to the existing discharge point under N. Kerr
Avenue, which may lead to increased potential for flooding.
Comment.
While it may be everyone's understanding that "only new development projects at airports are deemed permitted if they
meet the requirements of the Session Law, "SB 229 directs DENR to "accept alternative measures of stormwater control
at public airports." Further "in accordance with the Federal Aviation Administration August 28, 2007, Advisory
Circular No. 15015200-33B (Hazardous Wildlife Attractants on or Near Airports), the Department shall not require
the use of stormwater retention ponds, stormwater detention ponds, or any other stormwater control measure that
promotes standing water. One might argue that SB 229 does not only apply to new development.
Although I have not read the airport permit, it seems that the designated low density areas of the airport wood indeed
still subject to the master plan permit SW8 040836, issued on November 24, 2004, i.e., "Projects submitted for approval
under the low density option must demonstrate compliance with the low density criteria described in the latest version of
the stormwater rules. Projects that have clustered built -upon area, collection systems, or which do not provide for sheet
flow across at least 30' of grassed area will be considered high density."
I concur, piping of vegetated conveyance (except only minimal piping to convey runoff beneath an impervious surface or
to provide access) does not meet low density criteria. Further piping is not one of the alternative measures of
stormwater control that SB 229 directs DENR to accept.

Linda I'm saying that the proposed piping can't be approved under the current low density part of the Airport's
stormwater permit. You can propose to modify the stormwater permit to add a suitable BMP that meets our
requirements and the FAA (no permanent pool of water) to treat the runoff from the drainage area collected by that
pipe.
Comment:
1 concur, the proposed piping can't be approved under the current low density part of the Airport's stormwater
permit. Unless the airport provides overland flow, the airport can propose to modify the stormwater permit to add an
alternative BMP.
Linda Hey Mike. Robin Austin responded to my comments (her letter attached) about the proposed piping project at
the Wilmington International Airport. I'm not sure how to decode one of her statements. She says that the drainage
conveyance they are proposing to pipe existed prior to 1988 and that it should not be covered by the low density
permit. It sounds like she is trying to say that not all of the airport is covered by the low density permit, but that is not
true. The existing permit split up the airport into those high density areas that require treatment and the remaining low
density areas, where treatment is not required. We make decisions about whether to require treatment based on
whether a proposed project is within the designated high density area or not. That existing stream might be a "natural"
feature of the property that was there before 1988 and before we wrote the permit, but that doesn't make it OK to pipe
it today, right? I write low density permits every day that have existing natural drainage features, but we don't allow
them to be piped under the low density rules.
Comment:
I'm not familiar with the permit to comment on whether or not the drainage conveyance they are proposing to pipe
existed prior to 1988 or whether if not it is covered by the low density permit.
I do concur, that even if the existing stream is a "natural"feature of the property that was there before 1988, before we
wrote the permit, it doesn't make it OK to pipe it today.
Mike Randall
Stormwater Permitting Program
NC Division of Energy, Mineral and Land Resources (DEMLR)
1617 Mail Service Center
Raleigh, NC 27699-1617
Office: 919-807-6374
Cell: 919-389-7801
Email correspondence to and from this address may be subject to public records laws
From: Lewis,Linda
Sera: Friday, May 02, 2014 3:32 PM
To: Randall, Mike
Cc: Scott, Georgette
Subject: FW: ILM 3301-1003
Hey Mike. Robin Austin responded to my comments (her letter attached) about the proposed piping project at the
Wilmington International Airport. I'm not sure how to decode one of her statements. She says that the drainage
conveyance they are proposing to pipe existed prior to 1988 and that it should not be covered by the low density
permit.

It sounds like she is trying to say that not all of the airport is covered by the low density permit, but that is not true. The
existing permit split up the airport into those high density areas that require treatment and the remaining low density
areas, where treatment is not required. We make decisions about whether to require treatment based on whether a
proposed project is within the designated high density area or not.
That existing stream might be a "natural" feature of the property that was there before 1988 and before we wrote the
permit, but that doesn't make it OK to pipe it today, right? I write low density permits every day that have existing
natural drainage features, but we don't allow them to be piped under the low density rules.
Linda
From: Robin Austin [mailto:raustinOtbiilm.com]
Sent: Friday, May 02, 2014 1:35 PM
To: Lewis,Linda
Cc: Julie Wilsey
Subject: FW: ILM 3301-1003
Linda,
Have you had a chance to look at this request yet?
Please let me know.
Thank you,
Robin
From: Robin Austin fmailto:raustinOtbiilm.com]
Sent: Tuesday, April 22, 2014 3:23 PM
To: 'Lewis,Linda'
Cc: Julie Wilsey ([e-mail])
Subject: RE: ILM 3301-1003
Linda,
Please see the attached correspondence.
Thank you,
Robin
M. Robin Austin, P.E.
Talbert & Bright, Inc.
4810 Shelley Drive
Wilmington, NC 28405
Phone: [phone]
Fax: [phone]
From: Lewis,Linda[mailto:Iinda.lewis;(&ncdenr.gov]
Sent: Wednesday, April 09, 2014 11:34 AM
To: Robin Austin
Cc: Scott, Georgette
Subject: RE: ILM 3301-1003
I'm saying that the proposed piping can't be approved under the current low density part of the Airport's stormwater
permit.
You can propose to modify the stormwater permit to add a suitable BMP that meets our requirements and the FAA (no
permanent pool of water) to treat the runoff from the drainage area collected by that pipe.
Linda

From: Robin Austin [mailto:[e-mail]]
Sent: Wednesday, April 09, 2014 11:28 AM
To: Lewis,Linda
Subject: RE: ILM 3301-1003
Linda,
What do you need? Is this a revision since there's no additional BUA or change to BMPs?
Robin
From: Lewis,Linda rmailto:Iinda.lewisOncderingov]
Sent: Wednesday, April 09, 2014 11:18 AM
To: Robin Austin
Cc: Julie Wilsey; 'Whitney Prease'; Scott, Georgette; [e-mail]
Subject: RE: ILM 3301-1003
Robin:
Only new development projects at airports are deemed permitted if they meet the requirements of the Session Law for
sheet flow. Since the construction of new impervious area is not part of this drainage project, the deemed permitted
aspect of the Session Law does not apply.
However, the designated low density areas of the airport are still subject to the master plan permit SW8 040836, issued
on November 24, 2004. Per Section 1.12 of that permit:
"Projects submitted for approval under the low density option must demonstrate compliance with the low
density criteria described in the latest version of the stormwater rules. Projects that have clustered built -upon
area, collection systems, or which do not provide for sheet flow across at least 30' of grassed area will be
considered high density."
And per Section 11.9 of that permit
"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 stormwater plans, including, but not
limited to, those listed below:
a. Any revision to any item shown on the approved plans, including the stormwater management
measures, built -upon area, details, etc., that has an impact on the permitted stormwater facility.
b. Project name change.
C. Transfer of ownership.
d. Redesign or addition to the approved amount of built -upon area or to the drainage area.
e. Further subdivision, acquisition, lease or sale of all or part of the project area. The project area
is defined as all property owned by the permittee, for which Sedimentation and Erosion Control
Plan approval or a CAMA Major permit was sought.
f. Filling in, altering, or piping of any vegetative conveyance shown on the approved plan."
The proposed piping of that existing vegetated conveyance will not meet the low density criteria, which allows only
minimal piping to convey runoff beneath an impervious surface or to provide access to a lot.
Additionally, the County may want to weigh in on the increased runoff volume and flow rate to the existing discharge
point under N. Kerr Avenue, which may lead to increased potential for flooding.
Linda
From: Robin Austin fmailto:raustinOtbiiim.com]
Sent: Monday, April 07, 2014 9:38 AM
To: Lewis,Linda

r
Cc: Julie Wilsey; 'Whitney Prease'
Subject: FW: ILM 3301-1003
Linda,
Have you heard anything from Raleigh yet? When do you think you will hear something?
We received the NHC Stormwater Exemption on 4/2/14.
Robin
From: Robin Austin fmailto:raustin(dtbiilm.com]
Sent: Monday, March 24, 2014 9:24 AM
To: 'Lewis,Linda'
Subject: RE: ILM 3301-1003
We've received 401 approval (see attached). The 404 is still with the USACE until the coastal consistency determination
(submitted 2/20/14) has been approved. We submitted for a SEC permit from NCDENR on 3/14/14, and an exemption
from NHC Stormwater on the same day.
Robin
From: Lewis,Linda fmailto:linda.lewisC&ncdenr.gov]
Sent: Monday, March 24, 2014 9:12 AM
To: Robin Austin
Subject: RE: ILM 3301-1003
Thank you, I will keep you posted.
One of the comments I received from Raleigh was about notification to DWR about piping the stream and where that
application stood?
Linda
From: Robin Austin fmailto:raustin(dtbiilm.com]
Sent: Monday, March 24, 2014 9:05 AM
To: Lewis,Linda
Subject: RE: ILM 3301-1003
OK, please keep me posted. I also wanted to add that if you look at plan I sent you, we are actually increasing the length
of sheet flow for the runoff coming from the runway.
Thanks,
Robin
From: Lewis,Linda fmailto:[e-mail]]
Sent: Monday, March 24, 2014 9:00 AM
To: Robin Austin
Subject: RE: ILM 3301-1003
Robin- Your opinion has been noted. I will wait for the Central Office staff to give me their opinions before making a
decision.
Thanks,
Linda

From: Robin Austin fmaiito:[e-mail]]
Sent: Monday, March 24, 2014 8:54 AM
To: Lewis,Linda
Subject: RE: ILM 3301-1003
Linda — I disagree that it changes the previously deemed permitted runway by adding the piped system. Runoff from the
runway will continue to sheet flow across the grass (approx. 1050 ft) and will enter the new piped system, just as it
entered the existing stream. There is no change to the sheet flow with this project. The stream is channelized flow, and
the pipe will be channelized flow as well. There is no sheet flow occurring in the stream.
Robin
From: Lewis,Linda[mailto:linda.lewisC&ncdenr.gov]
Sent: Monday, March 24, 2014 8:32 AM
To: Robin Austin
Subject: RE: ILM 3301-1003
Robin- I think that the proposed project is changing the previously "deemed permitted" runway by virtue of adding the
piped system. It would seem to me that if the runway was deemed permitted because of the sheet flow that its runoff
received, then anything that proposes to change that sheet flow to piping should be evaluated. I'm trying to figure out if
the proposed project impacts the current deemed permitted status going forward, and if it does, what to do about it.
From: Robin Austin fmailto:raustinOtbiilm.coml
Sent: Friday, March 21, 2014 12:06 PM
To: Lewis,Linda
Subject: RE: ILM 3301-1003
Linda,
Does this apply even if there is no new impervious being created?
Robin
From: Lewis,Linda fmailto:linda.lewis(&ncdenr.gov]
Sent: Friday, March 21, 2014 11:58 AM
To: Robin Austin
Subject: RE: ILM 3301-1003
Robin
I'm trying to determine if the proposed project meets the session law requirements to be "deemed permitted.". I've had
to enlist some help from the central office. Their response has been a little slow.
The Session law requires the runoff from runways and taxiways to sheet flow through vegetated areas and buffers. I'm
worried about the proposed collection system and how that impacts the sheet flow requirement.
Linda
From: Robin Austin [mailto:raustin(dtbiilm.com]
Seat: Friday, March 21, 2014 11:54 AM
To: Lewis,Linda
Subject: ILM 3301-1003
Linda,
I sent you a request for a State Stormwater Exemption on 2/11/2014 for the Wilmington International Airport Runway
24 Wildlife & NAVAID Critical Area Mitigation project. What is the status of your review of that request? Please let me

know.
Thank you,
Robin
M. Robin Austin, P.E.
Talbert & Bright, Inc.
4810 Shelley Drive
Wilmington, NC 28405
Phone: [phone]
Fax: [phone]

ECEI E
April 22, 2014
APR 2 3 20%
Ms. Linda Lewis
NC Division of Water Quality BY.
127 Cardinal Drive Ext.
Wilmington, NC 28405
RE: Wilmington International Airport
Runway 24 Wildlife & NAVAID Critical Area Mitigation
TBI No. 3301-1003
SW8 040836
Dear Ms. Lewis:
In a letter to you dated February 11, 2014, we requested consideration that the referenced project
be exempted from stormwater permitting requirements. Through a series of email
correspondence between March 21, 2014 and April 9, 2014, your office's initial conclusion was
that the project could not be approved under the low density provisions of the airport's
stormwater master plan permit (SW8 040836), and that a suitable BMP meeting DWQ
requirements would be needed. I would like to request further consideration for an exemption
based on some additional information that may help clarify the project impacts in relation to the
existing permit.
The proposed project will convert an existing open channel network to a pipe network and
includes grading improvements totaling approximately 70 acres. The purpose of the project is to
mitigate wildlife attraction and NAVAID critical area hazards posed by the existing channel
network and grade irregularities in order to enhance aviation safety at a regional transportation
facility that encompasses 1,620.8 acres.
The project adds no built upon area and all on -site runoff patterns will continue to include sheet
flow over mildly sloping turfed areas and shallow concentrated flow in grass swales which
provide treatment prior to entering the collection system.. The project includes storage and
controls designed to attenuate the peak flows to approximate pre -construction conditions for a
10-year rainfall event. The on -site tributary area is about 119 acres, including 2.55 acres of
existing (pre-1988) built upon area. The off -site tributary area is approximately 191 acres.
In your email, you cited two subparagraphs of the permit:
I.12. -Projects submitted for approval under le low density option must demonstrate
compliance with the low density criteria described in the latest version of the stormwater rules.
Projects that have clustered built -upon area, collection systems, or which do not provide for sheet
flow across at least 30' of grassed area will be considered high density.
ENGINEERING & PLANNING CONSULTANTS
4810 SHELLEY DRIVE WILMINGTON, NC 28405 910.763.5350 FAx [phone]

II.9. - 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
stormwater plans, including, but not limited to, those listed below:
f. - Filling in, altering, or piping any vegetative conveyance shown on the approved plan.
The existing open channels in question, along with several other similar channels on airport
property, were shown on the stormwater master plan permit. drawings only as existing
topographic features. These channels carried no specific designation on the plans as vegetative
conveyances with any particular status under the permit. The open channels involved in this
project were constructed as part of a runway and taxiway extension project in the 1950's. In the
absence of stormwater treatment regulations at the time, the channels were designed and
constructed for the "primary purpose of transporting (not treating) runoff." Therefore, these
channels represent an existing stormwater collection system as defined by 15A NCAC
02H.1002(18). This project is modifying an existing (pre-1988) stormwater collection system,
rather than constructing an entirely new stormwater collection system.
We believe that the project as designed is consistent with the low density provisions of the
master plan permit. In accordance with sub -paragraph II.91, your office has been contacted with
regard to permit status. To summarize, we provide the following information:
1. The project does not add new built -upon area.
2. The project is modifying an existing (pre-1988) stormwater collection system.
3. The small amount of existing built -upon area tributary to the project is pre-1988 and
features sheet flow over grass shoulders.
4. The project provides for flow across more than 30 feet of grassed area.
5. The project is consistent with the "deemed permitted" provisions of G. S. 143-214.7 (c4),
as it is consistent with "...any other areas that provide for overland stormwater flow that
promote infiltration and treatment of stormwater into grassed buffers, shoulders and
grassed swales."
We ask that you further consider this project based on this additional information and
respectfully request that you concur that the project as designed is consistent with the stormwater
master plan permit. We are hopeful that the State can issue either a letter of exemption or a letter
of permit modification covering the project.
If you require additional information, please let me know.
Sincerely,
M. Robin Austin
c: Julie Wilsey/ILM

February 11, 2014
Ms. Linda Lewis
NC Division of Water Quality
127 Cardinal Drive Ext.
Wilmington, NC 28405
RE: Wilmington International Airport
Runway 24 Wildlife & NAVAID Critical Area Mitigation
TBI No. 3301-1003
Dear Ms. Lewis:
Enclosed is a layout plan for the above referenced project.
��V
FEB i 2014
BY•
2�12 �� 112
Because of the nature of the project, we request that the project be exempt from stormwater
management permit requirements. The project consists of drainage improvements to the Runway
24 end located at the Wilmington International Airport, Wilmington, North Carolina. The
project will include piping the existing stream and ditches, filling the existing jurisdictional and
isolated weltands and jurisdictional ditches and streams, and grading the areas located off the
Runway 24 end to drain to the new storm drainage structures associated with the new pipes.
There is no increase to the impervious surfaces for this project.
The design of this project will reduce potential wildlife hazards associated with the existing
stream arid weltands at the Runway 24 end, eliminate obstructions and potential obstructions to
the localizer and glide slope antenna, and reduce on -going maintenance costs incurred by the
Airport to keep the existing ditches cleared.
We have received approval of an Individual 401 Water Quality Certification from the Division of
Water Resources (USACE Action ID No. SAW-2011-00455) and have applied for an Individual
Permit from the US Army Corps of Engineers. We will be applying for a State Sedimentation &
Erosion Control Permit, and we have requested an exemption from New Hanover County
Stormwater Engineering.
If you require additional information, please let me know.
Sincere
M. Robin Austin
Enclosure
ENGINEERING & PLANNING CONSULTANTS
4810 SHELLEY DRIVE WILMINGTON, NC 28405 910.763.5350 FAX [phone]