20060200 Ver 2_Staff Comments_20100701

Kulz, Eric
From: Kulz, Eric
Sent: Thursday, July 01, 2010 1:00 PM
To: Xu, Lin
Cc: Hill, Tammy; 'Tugwell, Todd SAW'; Johnson, Alan; '[e-mail]';
Dorney, John
Subject: Five Mile Branch - Iredell County (#2006O200v2)
Lin
DWQ has reviewed the above-referenced project documents and have a number of issues which require clarification
and/or possible discussion by the IRT. The majority of the issues are related to the proposed wetland restoration.
Vegetation
Sweetgum and red maple should be removed from the planting list for the project. Although these species are common
in Piedmont/Mountain Bottomland Hardwood communities, they tend to be very competitive in early successional
systems (such as recently-planted mitigation sites) and will likely colonize on their own.
Proposed Wetland Restoration Area Delineation
It is unclear how the extent of restored wetland was estimated. The boundaries of the proposed wetland restoration in
the design plan sheets do not appear to follow topographic contours or hydric soil lines. Please provide further
explanation and additional maps, if necessary, to clarify how the total proposed wetland restoration area was calculated
and mapped.
Vernal Pnnls
While we support the inclusion of a small number of vernal pools on a wetland restoration site, the mitigation plan does
not provide details regarding the number and total area of constructed pools. These factors are significant since the
plan proposes that they be included in the area receiving wetland mitigation credit.
Soil
While the site does appear to have hydric (Wehadkee) soil inclusions, we are concerned about the extent of wetland
restoration (58.6 acres) proposed on an area that contains primarily Chewacla soils. We echo the concerns expressed in
the original DA permit (May 9, 2006) as well as the suggestion that EEP not use any of the proposed wetland credits to
offset permitted impacts until such time as success of wetland restoration begins to be demonstrated.
Hydrology Success Criteria
The proposed performance criteria for hydrology are "saturation within 12 inches of the soil surface for the hydroperiod
dictated by the project reference or 5% of the growing season, whichever is less." DWQ believes that a hydroperiod
reaching the minimum of these criteria will be inadequate to support the wetland system targeted for restoration.
Table 5 in the Corps' 1987 Wetland Delineation Manual shows that areas with continual saturation or inundation for less
than 5 percent of the growing season in most years are not wetlands, and DWQ does not support wetland mitigation
credit for such areas. As Bottomland Hardwood Forests are expected to be "intermittently to seasonally inundated for
long duration" (NC Wetland Assessment Method, ver. 1, April 2008), and based on results of reference hydrology
monitoring in 2005 (Mitigation Plan, Dec 2009, p. 6-2), we expect that the targeted hydroperiod is significantly greater
than 5 percent, and varies depending upon landscape position (elevation, proximity to streams and surface runoff
sources, etc.).
In addition, although the mitigation plan indicates that monitoring will be representative, it does not include details
regarding the placement of monitoring plots for vegetation and hydrology. Please provide a map and description of how
monitoring will be structured to capture conditions across the site, including the hydrology gradient from the ditches
that will remain open adjacent to 1-40.
Monitoring Duration
Please note that the federal Mitigation Rule states that monitoring periods should be extended for forested wetlands.
This policy has been adopted by the IRT in NC. Considering the concerns regarding restoration on Chewacla soils, an
extended monitoring timeframe for both vegetation and hydrology may be warranted.
Please note we have copied pertinent USACE representatives and request input from them in resolving these issues.
Please feel free to contact Tammy Hill at [phone] or me if you have any questions regarding these comments.
Eric
Eric W. Kulz
Environmental Senior Specialist
N.C. Division of Water Quality
401 Oversight and Express Permitting Unit
2321 Crabtree Blvd., Suite 250
Raleigh, NC 27604
Phone: [phone]
Fax: [phone]
E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be
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