20071841 Ver 1_More Info Received_20080222

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R E G I O N A L A I R P O R T
February 21, 2008
Mrs. Cyndi Karoly
401 Permitting Unit
1650 Mail Service Center
Raleigh, NC 27699-1650
Subject Property: Asheville Regional Airport Expansion .i-
DWQ Project # 07-1841'.
Buncombe County FEB 2 2, 2008
DENK - +NAI EK QUAU'17
RE: Request for more information WETLANDS AND STORMWATER BRANCH
Mrs. Karoly:
In response to the letter Request for More Information dated January 23, 2008 from Mr.
Roger C. Edwards, please see the following responses:
DWQ Request:
Impact Justiflcation (Avoidance and Minimization)
Under Section Vll of your application you have not provided a 'justification" for the
impacts as requested within this section. Additionally, there are no "alternatives"
presented for this fill activity. At a minimum, you must explore all other available
properties for possible utilization for this proposed expansion.
Response:
The following is an excerpt from the USACE IP-404 Permit Application:
Alternatives
1. Avoidance
The expansion of the existing airport development to the north occurs on a site which is
bisected by a perennial stream. Development to one side or the other of the stream
would not yield sufficient development area to satisfy the project purpose and need.
The stream cannot be relocated to the east due to shallow bedrock to the ground
surface and topographic constraints. The stream cannot be relocated to the west due to
61 Terminal Dr., Suite 1, Fletcher, NC 28732 • Phone [phone] • Fax [phone]
www.flyavl.com
FAA restrictions on open water and forested buffers adjacent to runways due to safety
issues.
II. Minimization
Minimization of impacts to downstream aquatic resources will be accomplished by filling
the area so that grade directs storm water flows away from surface waters and into off-
line storm water BMP treatment measures.
The Asheville Regional Airport Authority and its agents have reviewed alternatives for the
development of the expansion area including the following:
Alternative 1 - No Build Alternative
The No-Build Alternative will result in no impacts to jurisdictional streams or wetlands
but does not satisfy project purpose and need to provide airside access to airstrip and
groundside access to four lane interstate with approximately 450,000 square feet of new
ramp, apron and taxiway; approximately 200,000 new square feet of building and
approximately 150,000 new square feet of roadway and parking. This alternative does
not provide for disposal of fly ash as alternative to utilizing valuable landfill space.
Alternative 2 - Off-Site Development Alternative
The Off-Site Development Alternative will result in no impacts to jurisdictional streams or
wetlands on this site but does not satisfy project purpose and need to provide airside
access to airstrip and groundside access to four lane interstate with approximately
450,000 square feet of new ramp, apron and taxiway; approximately 200,000 new square
feet of building and approximately 150,000 new square feet of roadway and parking.
This alternative does not provide for disposal of fly ash as alternative to utilizing valuable
landfill space.
Alternative 3 - West Side Development Alternative
The West Side Development Alternative will result in impacts to jurisdictional streams
and also does not satisfy project purpose and need since it does not have direct access
to four lane interstate and terminal. The USGS topographic map shows a "blue line"
stream in this location. This alternative does not provide for disposal of fly ash as
alternative to utilizing valuable landfill space.
Alternative 4 - South Side Development Alternative
The South Side Development Alternative will result in no impacts to jurisdictional
streams or wetlands but does not satisfy project purpose and need since it does not
enough land area adjacent to both airstrip and interstate to provide the necessary
program elements. This alternative does not provide for disposal of fly ash as alternative
to utilizing valuable landfill space.
Alternative 5 - East Side Development Alternative
The East Side Development Alternative will result in no impacts to jurisdictional streams
or wetlands but does not satisfy project purpose and need since it is not adjacent to
airstrip and does not have enough land area to provide the necessary program elements.
This alternative does not provide for disposal of fly ash as alternative to utilizing valuable
landfill space.
Alternative 6 - Reduced Scope and Scale Alternative
The Reduced Scope and Scale Alternative will result in fewer impacts to jurisdictional
streams or wetlands but does not satisfy project purpose and need to provide airside
access to airstrip and groundside access to four lane interstate with approximately
450,000 square feet of new ramp, apron and taxiway; approximately 200,000 new square
feet of building and approximately 150,000 new square feet of roadway and parking.
Reducing the scope and scale would render the project not economically feasible. This
alternative provides less area for disposal of fly ash as alternative to utilizing valuable
landfill space.
Alternative 7 - On-Site Northern Development Alternative (Preferred Alternative)
The On-Site Northern Development Alternative will result in unavoidable impacts to
jurisdictional streams or wetlands on this site but it does satisfy project purpose and
need to provide airside access to airstrip and groundside access to four lane interstate
with approximately 450,000 square feet of new ramp, apron and taxiway; approximately
200,000 new square feet of building and approximately 150,000 new square feet of
roadway and parking. This alternative does provide for disposal of fly ash as alternative
to utilizing valuable landfill space. Negative effects to downstream water quality and
important aquatic functions and values will be prevented through appropriate erosion
and sediment control methods during construction and the incorporation of permanent
storm water management measures designed to remove Total Suspended Solids JSS)
before they reach downstream receiving waters.
Alternative 8 - An additional alternative suggested by the NCDWQ was to relocate the
stream to the east side of the development. The topography of the site will not allow a
proper relocation of the stream due to the drastic elevation change across the site.
DWQ Request:
2. As the Division of Water Quality utilizes it's General Certification as Guidance for
Individual Impacts requests, and the General Certifications specify clean fill, your
proposed use of fly ash is not suitable for use in filling streams and wetlands. You
must re-submit your request showing the Non-Discharge Permit setbacks, with
appropriate liners and monitoring to ensure that water quality standards are not
contravened.
Response:
As shown in the enclosed drawings, the creek and wetlands will be filled with clean fill
material from nearby borrow areas or quarries (porous material discussed below). This
fill will be of sufficient depth to cover by at least two feet the top of the pipe that will
convey the relocated stream. As required in Condition 11. 9. of the non-discharge permit,
approval will be obtained from the Aquifer Protection Section of the Asheville regional
office for this design that protects the stream and groundwater with clean fill and a
geosynthetic clay liner with a maximum hydraulic conductivity of 10-6 cm/sec. These
measures, along with the containment of the stream within the pipe, justify waiver of the
prohibition of ash placement within 50 feet of surface water, as allowed by the permit.
There are no water supply wells or springs within 100 feet of the fill.
The ash non-discharge permit requires the bottom of the ash fill to be a minimum of one
foot above the seasonal high groundwater level. With regard to potential contact with
groundwater, the project will have porous material in the former steam bed and under
the reinforced concrete pipe to allow for drainage of groundwater from underneath the
fill and therefore impede the groundwater table from reaching the bottom of the ash fill.
As stated above, both the former stream bed and the reinforced concrete pipe will have
a minimum of two feet of clean fill over them, and for an extra measure of protection, a
geosynthetic clay liner over the clean fill and under any ash fill.
When completed, the project will have a six feet thick compacted clean fill "cap" over it
and it will then be mostly paved with an engineered drainage system to divert
stormwater around the fill, so infiltration of water into the fill is expected to be minimal.
The side slopes will have at least two feet of clean fill over the ash fill.
We believe that the above measures provide suitable protection of the stream and
wetlands downstream of the project and comply with requirements of the non-discharge
permit. If the Division deems monitoring is necessary, there is an existing monitoring
well both up gradient and down gradient. We will work with the Aquifer Protection
Section to provide whatever groundwater monitoring is required. If necessary, samples
may also be taken from the stream at appropriate locations both upstream and
downstream of the activity after the project is completed.
DWQ Request:
As it was observed that nutrients and petroleum products were making their way
into the stream system, your submitted stormwater collection and treatment system
must also capture an treat all impervious areas adjacent, or connected to, this fill
activity to adequately treat said runoff prior to discharge.
Response:
The submitted stormwater collections system was intended to separate all new
impervious and pervious development stormwater runoff from the existing airport
stormwater system. This was to be accomplished through the extension of the existing
60" RCP storm drain outlet, allowing no addition flow. The airport will work with their
engineer to propose a practicable stormwater collection and treatment system solution.
We thank you for your time in this matter. If you have any questions or require
additional information, please do not hesitate to contact me.
Sincerely,
Asheville Regional Airport Authority
David N. Edwards, AAE
Airport Director
cc: DWQ Asheville Regional Office
USACE Asheville Regulatory Field Office
David McHenry, NC Wildlife Resources Commission
Asheville Regional Airport Authority Files
WK Dickson - Gary Dickson
Carolina Wetlands - Craig Wyant
Charah - Charles Price
Progress Energy - Cam Wheeler

6' COMPACTED
SOIL CAP
C ASH PLACEMENT
-- --- 2'---
MAX 1X 10 cm/sec
GEOSYTHETIC CLAY
LINER MATERIAL
, 60" PIPE L..-
3'
PREPARED SUBGRADE -
# 57 DRAINAGE STONE
OR EQUIVALENT
T WIDE CONNECTING TRENCH
TO BE INSTALLED AT 100'+/-
INTERVALS AND FILLED WITH
#57 DRAINAGE STONE OR
EQUIVALENT
TYPICAL PIPE SECTION
N.T.S
(`) TOP OF FILL - 6'
SIDE SLOPES - 2'
SOIL BACKFILL
Y. L y
EXISTING DRAINAGE CHANNEL
TO BE FILLED WITH #57
DRAINAGE STONE OR
EQUIVALENT
COMPACTED
CHARAH
ASHEVILLE REGIONAL AIRPORT
FLY ASH BENIFICIAL USE PROJECT
CONSTRUCTION DETAIL REVISION
FEBRUARY 2008
SOIL CAP
24" ASH PLACEMENT
18
'IMIN
of
TYPICAL LINER SECTION
MAX 1 X 1ecm/sec
GEOSYTHETIC CLAY
LINER MATERIAL
N.T.S