20110252 Ver 1_More Info Received_20110629

June 28, 2011
Ms. Karen Higgins, Supervisor
Wetlands, Buffer, Stormwater, Compliance and Permitting
NCDENR, DWQ
1650 Mail Service Center
Raleigh, NC 27699-1650
RE: Calabash Town Center -AFTER-THE-FACT
DWQ Project # 11-0252; Brunswick County, NC
Dear Ms. Higgins,
D
JUN 2 9 2011
NR . py
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Thank you for your letter dated May 20, 2011 in which you request additional
information regarding the after-the-fact 401 Water Quality Certification application submitted
for the Calabash Town Center. Below is a response to each of your concerns.
You indicate in Item 1 that "DWQ believes that the wetlands which currently lie between
the state stormwater ponds on site exhibited all three required wetland criteria (hydric soils,
hydrophytic vegetation, wetland hydrology) both after the construction of the above mentioned
ditch and prior to the installation of the state stormwater ponds." In support of this opinion, you
cite an LMG letter written to the US Army Corps of Engineers (USAGE) on 9/27/2007 and the
subsequent issuance of the Notification of Jurisdictional Determination on 2/22/2008. Please
note that LMG did identify a drainage effect sufficient to remove wetland hydrology adjacent to
the existing ditch. A conservative drainage effect distance of 50 feet was estimated by the
USACE representative at the time of the site meeting. Given the limited scope of the work being
conducted at the time, the determination of the lack of jurisdiction by the USACE, and the lack
of knowledge of specific future land plans, no additional site testing or evaluations were
conducted to determine the specific extent of the drainage impact of the boundary ditch in
question. At the time, the only option to challenge the estimated drainage effect of the boundary
ditch would be to conduct long-term hydrologic monitoring (a process that was cost- and time-
prohibitive to the land owner).
The USACE has since formally recognized the use of other hydrologic tools used to
identify limits of wetland hydrology in areas previously impacted by human activities (e.g.
ditching) as identified in the Regional Supplement to the Corps of Engineers Wetland
Delineation Manual: Atlantic and Gulf Coastal Plain Region (Version 2.0). These additional
tools include DrainMod analysis; "scope and effect" calculations; and NRCS state drainage
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington, NC 28402
guides. Note that the NRCS Southeast Coastal States Wetland Team published lateral drainage
effects for ditches of varying depths in different soil series. For Group D Sandy Soils (consistent
with those occurring on-site), the NRCS has identified a lateral effect of 415 feet for one 4-foot
ditch. Using DrainMod, the effective lateral drainage distance for a 4-foot ditch in Murville soils
is 275 feet. Given these accepted hydrologic tools, the boundary ditch in question does indeed
have a greater lateral drainage effect than that agreed to during the Corps site meeting in 2007.
You further referenced letters submitted by LMG on 02/22/2008, 05/28/2008 and
09/02/2009 attesting to the seasonal high water table (SHWT) on the project site in reference to
various stormwater permits being applied for at various times through the site's history.
LMG made each assessment on the above mentioned dates as part of the regulatory
requirements to obtain the necessary permits for the project development. SHWT -determinations
are routinely performed as part of this process. In each case the standard of practice is to use
redoximorphic features to make the determination. It is done on-site, requires a soil boring and
no additional site testing is performed. This procedure provides the necessary data, is cost
efficient and can be accomplished in a timely manner. It is important to note that a
redoximorphic feature may be identified in an area that has been drained and no longer meets
wetland hydrology. In addition, a SHWT determination does not identify the duration or
frequency of inundation. For these reasons, a SHWT determination should not be used to imply
that the wetland hydrologic criterion is met. Indeed, SHWT determinations are not an accepted
indicator for wetland hydrology.
In Item #2 you state that "the DramMod analysis submitted does not relate to whether or
not the stormwater ponds themselves will have an impact upon the wetlands" and that if the
adjacent ditch did remove hydrology from the wetlands prior to the installation of the pond, then
the ditch would act as a significant nexus and be 404 jurisdictional wetlands.
The DrainMod analysis is a comprehensive, quantitative assessment of a site's hydrologic
profile. Based on this analysis, the ditch effect supersedes any effect the subsequent stormwater
ponds may have had on the site due to removal of the hydrologic component in the 1980's.
During her site inspection, Jennifer Frye with the USACE agreed that the ditch was having a
drainage effect. In the absence of any long-term hydrological data, a 50-ft offset from the ditch
was agreed upon. Note that the wetland boundary depicted on the previously submitted site plan
was incorrect. The 50-ft offset was not shown for the larger of the two wetland pockets. Attached
is a new site plan showing the correct USACE-approved boundaries. Direct wetland impacts are
1.87 acres. We apologize for this error.
Note that the USACE made a determination that the wetland areas do not have a
Significant Nexus (SN) to a Traditional Navigable Water (TNW) with the knowledge that the
existing boundary ditch exhibited a lateral drainage effect that altered site hydrology. The SN
determination was not premised on this condition, but rather other observed conditions including
a discontinuous Ordinary High Water Mark (OHWM) in conveyances situated down-gradient
from this location.
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington, NC 28402
In Item #3, you require that mitigation be offered at a 2:1 ratio. The applicant agrees to
buy into the Stone Farm Mitigation Bank for the restoration of 1.87 acres of non-riparian
wetlands and to preserve 9.65 acres of wetlands (5 x impact acreage) located in a nearby site. We
believe this mitigation proposal meets the requirements of 15A NCAC 02h.1305.
Thank you for your comments. We understand that a meeting with USACE and DWQ
representatives may be our next step. Let me know if you would like us to coordinate this.
Sincerely,
Kim Williams
Environmental Scientist
A? t,
G. Craig Turner d
Vice President
NC Licensed Soil Scientist, # 1091
SC Certified Soil Scientist #57
C: Mr. Jim Myers
Mr. Chad Coburn, DWQ
Ms. Jennifer Frye, USACE
Mr. Phil Norris, Norris & Tunstall
Encl.
www.lmgroup.net • [e-mail] • Phone: [phone] • Fax: [phone]
3805 Wrightsville Ave., Suite 15, Wilmington, NC 28403 • P.O. Box 2522, Wilmington, NC 28402
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