20011729 Ver 1_Staff Comments_20010209

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MEMORANDUM
TO: Bob Zarzecki
FROM: Amanda Mueller
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E., Director
Division of Water Quality
SUBJECT: Comments on "Conceptual Wetland and Stream Mitigation Plan for the Rocky
River Lower Reservoir Expansion Chatham County, North Carolina: Submitted 23 January
2003"
DATE: February 9, 2004
My review of this document focused primarily on the sections related to the Wetland Mitigation
for the project. Although NC-DWQ is not requiring stream mitigation, one general comment is
that the plan does not show any success criteria for the on-site stream enhancement areas. The
following comments/concerns arose while I was reviewing the Wetlands mitigation sections of
the plan:
1) Wetland Success Criteria (p. 30):
a. The wetland hydrology criteria needs to be stated clearly so that there is no question as to
what determines hydrologic success (i.e. The success criteria will be inundation or
saturation within 12 inches of the surface for at least 12% of the growing season.
Supplemental goals of the hydrologic data will be to be +/- 2 inches of that in the
reference area.). As it is clearly stated there are two potentially different measures of
success.
b. The vegetation success criteria of, "at least 260 trees/acre of the approved planted
species ...for at least 5 years" must be on all acres of the restoration (3.36 acres), creation
(11.44 acres), and enhancement (7.32 acres) areas (total = 22.12 acres) where the planting
of woody vegetation is proposed, not only on 14.9 acres as stated.
c. A success criteria for the herbaceous vegetation cover should also be established (e.g.
Herbaceous vegetation success is defined as achieving a dominance of wetland
vegetation (FAC or wetter indicator status) with greater than 85% cover on the site by the
end of the 5-year monitoring period.)
d. A success criteria needs to be established for the Fringe Wetland areas (e.g. 85%
herbaceous vegetation cover after 5 years, or vegetation cover within 10% of the percent
cover for the reference fringe wetland, etc.).
2) Reporting (p. 29): It needs to be specified that the numbers for the vegetation density and
percent cover data will be presented in the monitoring reports.
2?L7
N. C. Division of Water Quality, 401 Wetlands Certification Unit,
1650 Mail Service Center, Raleigh, NC 27699-1650 (Mailing Address)
2321 Crabtree Blvd., Raleigh, NC 27604-2260 (Location)
[phone] (phone), 919-733-6893 (fax), (http://h2o.enr.state.nc.us/ncwetlands
3) Monitoring Activities (p. 26 & 29):
a. Monitoring wells should also be placed in the areas of highest elevation on the site to
ensure the hydrologic success criteria are being met throughout the site. This realizes
that the center and corners of the site may not be the areas of highest elevation.
b. The vegetation in the wetland enhancement and wetland fringe areas also needs to be
monitored to determine success for the sites.
c. Given the size of the restoration/creation areas (MW-01 and MW-02) and the fact that
they are not continuous nine 1Om x IOm plots should be done in MW-O1 and four or five
10m x 10m plots should be done in MW-02.
d. A site walk-though should be done annually to make general observations, search for
problem areas, and assess the general health and appearance of planted vegetation. The
results of the walk-though should be reported in the monitoring reports.
4) General Comments/Concerns:
a. Proposed restoration credits are 1.5:1. Based on the other mitigation ratios used, it
appears as though the restoration credits should be 2:1 providing 1.68 acres of credit
instead of 2.24 acres of credit. This would bring the total mitigation credits to 9.13 acres,
which does not sufficiently account for all the impacted area.
b. Fringe Wetlands:
1. 4.45 acres of new fringe wetland are projected for the new reservoir project. There is
concern about whether this is an accurate prediction, and what measures will be taken
to account for any shortfalls in acreage.
2. How and when will the fringe wetland acreage be determined? -
3. Will there be any seeding, planting, or other vegetation enhancement done on the
projected fringe wetland areas?
c. No time lines are presented for dam construction and flooding, and wetland creation and
restoration.
d. It is unclear what "Restoration" activities will be taking place to "restore" the acres of
current wetlands on MW-01 and MW-02.
e. There is often concern with a wetlands' ability to be self-sustaining if fertilizers are
required on the site in the first 1 or 2 years and is then discontinued.
f. It appears that the calculated mitigation numbers are not accurate in the text for MW-02
(p.20). The proposed totals should be 4.84 acres not "4.48 acres." The tables seem to
have the accurate values, but the text should be corrected.
g. Some of the Legend features on the figures are difficult to differentiate on the figure itself
(e.g. Perennial Streams and Existing Reservoir Boundary, Mitigation Wetland 1 and
Mitigation Wetland 2, etc.)