20090430 Ver 2_More Info Received_20100422

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community infrastructure consultants
April 20, 2010
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APR ? N 20110
Mr. Ian Mcmillan DENR•KATEgW LRY
Division of Water Quality MTUNCSANDSTOStONArM PMCH
401 Wetlands Unit
2321 Crabtree Blvd., Suite 250
Raleigh, NC 27604
RE: 401 Water Quality Certification No. 3822 for Johnston County Airport
Mr. McMillan:
Johnston County Airport (Airport) has not yet received a 404 Individual Permit from the US Army
Corps of Engineers for the proposed Runway Safety Area and Corporate Area Development. The
USACE has not requested additional information or indicated any concerns or extenuating
circumstances. The 401 Certification Condition No. 6 stated that mitigation must be purchased
from EEP within 60 days of the issuance of the 401 Certification (24 February 2010). The Airport is
unable to meet this 60 day timeframe due to the delay in receiving the 404 Permit and is
requesting a 60 day extension to this condition. The requested date to complete the mitigation
credit purchase is 24 June 2010. The Airport is also soliciting proposals from commercial
mitigation providers in an effort to reduce mitigation costs. Only approved mitigation banks in the
Neuse 01 watershed will be considered and any selected mitigation provider will be approved by
DWQ prior to credit purchase. The Airport has not selected an alternative provider to EEP but is
exploring that alternative.
Due to construction funding shortfalls and recent decreases in corporate air travel, the Airport
wishes to proceed to construction only with the FAA mandated Extended Runway Safety Area
(ERSA). Construction of the proposed Corporate Area will be revisited as need and funding
dictates. As such, the Airport is requesting that the required mitigation only be purchased for the
ERSA impacts. These impacts include: 685 linear feet of stream; 7.73 acres of riparian wetland;
44,496 square feet of Zone 1 buffer; and 28,474 square feet of Zone 2 buffer.
Thank you for your attention to these items and please contact me if you have any questions or
require any additional information.
Sincerely,
& o., Inc.
U7
Daniel P. Ingram
Project Manager
cc: Carroll Triplett, WK Dickson
Thomas Brown, USACE
Ray Blackmon, Johnston County Airport
Chastity Clark, NCDOT DOA
Project file, 80324.00.CA
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8. DIFFUSE FLOW REQUIREMENT. The purpose of the diffuse flow requirement is to retain the
pollutant removal functions of the riparian buffer for new stormwater discharges to surface
waters. The diffuse flow requirement may be met in one of the following ways:
a) Allowing stormwater to run off of developed areas in a diffuse manner without the use
of a ditch, swale, pipe or other device to concentrate runoff.
b) Converting concentrated runoff from new ditches or manmade conveyances to diffuse
flow before the runoff enters Zone 2 of the riparian buffer. Downslope of diffuse flow
devices, the riparian buffer must be stabilized with vegetation, which must be
maintained in perpetuity. Corrective action to restore diffuse flow shall be taken if
necessary to impede the formation of erosion gullies.
c) Treating stormwater in a stormwater best management practice that provides a
minimum of 30 percent removal of total nitrogen and 30 percent removal of total
phosphorus. The best management practice must be located outside of both zones of
the riparian buffer but may discharge through the riparian buffer in accordance with the
provisions in Item (9). In addition, the best management practice must comply with
current DWQ design standards.