NCG150069_Email RE Outfall Updates_20230922

Cook, Brittany
From: Dan Drennan <[e-mail]>
Sent: Friday, September 22, 2023 9:20 AM
To: Cook, Brittany
Cc: Cathleen Barmoy; Amelia Ryan
Subject: [External] NCG150069 Rowan County Airport - Outfall Change
Attachments: Rowan County Airport Photolog.pdf, 3830 Airport Loop-Salisbury SM_rev1.pdf
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Hello Brittany,
For General Permit Certificate of Coverage No. NCG150069 for the RBS Hanger at the Rowan County Airport,
there is a need to change the outfall location. Since the Certificate of Coverage was issued on August 11, 2022,
no discharge has been reported at the outfall during most rain events. After observation of runoff in a variety of
flow conditions, it has become apparent that the majority of stormwater runoff from the relevant drainage area
does not reach the storm drain designated as Outfall 001. While this location appears to collect runoff from the
immediate surrounding area, grass overgrowth and grading contours divert most stormwater in another
direction. The current stormwater runoff flow is shown in the attached photo log. Runoff mostly flows along the
side of the road in a shallow channel at the edge of the roadway until it exits the property, crosses the road and
flows into the adjacent vegetated area where it mixes with drainage from the hanger roofs and tarmac catch
basins.
It is proposed that the Outfall location be moved to more accurately reflect where discharge from the property
occurs. No other information about the Outfall would be changed. Sampling would now occur approximately 14
feet away, at the end of the shallow channel made by the sloped roadway and grass before water begins sheet
flowing across the road as shown in Figure 1. The coordinates for the original and new proposed location are
provided below.
Latitude Longitude
Original Outfall 001 35.637502 -80.519477
Proposed Outfall 001 35.637531 -80.519446
Please let me know if this outfall change can be approved and if any additional documentation is required.
Thank you,
Dan Drennan, PE
Principal Engineer
i

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LEGEND
———— PROPERTY BOUNDARY(APPROXIMATE)
Q ORIGINAL OUTFALL 001 LOCATION
r _" DRAINAGE AREA
L_ i
0 DOUBLE-WALLED JET FUEL AST
• PROPOSED NEW OUTFALL 001 LOCATION
- ADDITIONAL DRAINAGE AREA
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SPILL KIT
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©2021 Google, Imagery Date:01/22/2021.
a Rowan County Interactive Map Viewer.
Site Map
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2 / '� 3830 Airport Loop
m Salisbury, North Carolina
~� Drawn Date
/23
Designed
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Desi ned Figure
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Approved
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Photo/Ima e Log 9 �,I
Photograph Log of Stormwater Flow Path
Client: ADUA Distribution Project: NPDES Permit Outfall Update
Site Name: Rowan County Airport—RBS Hanger Site Location: 3830 Airport Loop, Salisbury NC,
28147 _I
Image ID: #1
Location: AST Area
Direction: North
Date: 7/24/2023
Comments:
f a -
AST area with stormwater r
flow path marked in red
Page 1

Photo/Ima e Log 9 �,I
Client: ADUA Distribution Project: NPDES Permit Outfall Update
Site Name: Rowan County Airport—RBS Hanger Site Location: 3830 Airport Loop, Salisbury NC,
28147
Image ID: #2
Location: Property
Boundary
Direction: Northeast
Date: 7/24/2023
Comments:
4
I
Northeast corner of the
Facility with stormwater flow
path marked in red and
current outfall location
marked in yellow.
Page 2