20100642 Ver 1_USACE Correspondence_20100813

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REPLY TO
ATTENTION OF'.
CESA W-RG/Tugwell
MEMORANDUM FOR RECORD
August 13, 2010
SUBJECT: Comments on Draft Prospectus for the proposed La Foresta Stream Mitigation Bank
1. Purpose: The purpose of this memo is to provide comments on the Draft Prospectus for the La
Foresta Stream Mitigation Bank. These comments address the specific requirements identified
in the April, 2008, the Federal Mitigation Rule (Rule), which establishes the standards and
criteria for the use of all types of compensatory mitigation, including on-site and off-site
permittee-responsible mitigation, mitigation banks, and in-lieu fee mitigation to offset
unavoidable impacts to waters of the United States authorized thought the issuance of
Department of the Army (DA) permits pursuant to Section 404 of the Clean Water Act (33
U.S.C. 1344) and/or Sections 9 or 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. 401,
403).
2. Background: The site for the proposed La Foresta Stream Mitigation Bank was previously
reviewed in the field on April 281". Comments made during this meeting were taken into account
during the preparation of the Draft Prospectus.
3. Draft Prospectus Comments: In general, the Draft Prospectus appeared to be lacking in
several areas that are specifically required by the Rule (see below). The primary concern
associated with the bank has to do with the proposal to move the channel away from its current
location, which appears to be its natural and historic location. This, along with the inability to
provide a full 50-foot wooded buffer, are significant concerns that, if not addressed in the Final
Prospectus, would be fatal flaws with the proposed bank.
The following specific comments pertain to the Draft Prospectus:
• The stated objectives of the mitigation bank identify five areas where improvements will
be made. These objectives do not include a discussion about the type of mitigation that
will be produced by the bank (stream, buffer, wetland, etc.) or the approximate quality
that might be produced. Additional information to address this would be helpful.
• No discussion is in the Draft Prospectus about how the mitigation bank would be
established and operated.
• The Proposed Service Area section of the document identifies the location of the bank but
does not seem to specifically request a particular service area. Additional clarification as
to the expected service area as defined in the Rule.
DEPARTMENT OF THE ARMY
WILMINGTON DISTRICT, CORPS OF ENGINEERS
69 DARLINGTON AVENUE
WILMINGTON, NORTH CAROLINA 28403-1343
• The Need and Feasibility of Mitigation Bank section states that the Cape Fear Basin
includes developing urban centers. The discussion includes information about how
degraded the proposed site is, but does not go into any further detail about the need for a
bank in this watershed (i.e., demand for credits).
• There is no discussion about the proposed ownership arrangements or long-term
management strategy for the bank. The Need and Feasibility section states that it will no
longer be possible to proceed with the proposed single-family subdivision in the area of
the bank once the bank is established. It is not clear from the subdivision plat that this is
the case. It appears that remaining portion of the site may still be used for development.
What would be the future proposed use of the site following establishment of the bank?
• Qualifications of the proposed sponsor are not included.
• The project does provide some information about the ecological suitability of the site to
provide mitigation in the Need and Feasibility Section, but there are concerns about how
the proposal will support the planned types of aquatic resources. It appears that the
proposal is to move the stream upslope to the east so that the stream is no longer under
the transmission line. There are several major problems associated with this:
o Moving the stream upslope away from the low point of the valley produces a
situation where flows will move to the bottom of the valley during flooding
conditions. Over time this could cause instability within the stream, possibly
resulting in the migration of the stream back to its current location and condition.
Also, if the flood flows follow the valley slope, it is unclear how these flows will
be encouraged to move back to the constructed stream location at the downstream
end of the project.
o Moving the stream uphill and raising the bed to reconnect it to the floodplain may
disconnect the stream from groundwater, resulting in adverse base flow
conditions, particularly during drought periods.
o There is no plan shown to connect the small tributary that comes into the main
channel from the west across the transmission line easement into the new channel.
o At the very upper end of the project, it appears that there may be a stream that
comes into the site from the northwest. How will this stream be connected to the
new channel alignment?
o The project description mentions that it would be necessary to have a reduced
buffer on the west side of the project where it adjoins the transmission line
easement, but it appears from the Site Map that the buffers will be substantially
less than the required 50 feet on both the west and east sides of the stream, with
areas where the stream looks to abut the proposed easement. If the stream cannot
be located a sufficient distance away from the transmission line easement to
develop a buffer that can effectively protect the stream, the proposal does not
meet the minimum requirements to be a viable stream mitigation bank. Please
note that draft Federal/State guidance for determining stream credits generated
with projects with non-standard buffer widths is now out for comment (available
on our website). This guidance states that no credit can be generated where
buffers are not at least 15' in width from top of stream bank in the piedmont and
coastal plain.
o The relocated stream appears to cross through 2 potential wetland areas. These
areas would be adversely affected by the construction of a stream project within
their boundaries. A jurisdictional delineation should be conducted on the site to
identify the limits of Corps jurisdiction. Furthermore, if wetland areas lost as a
result of the project and not replaced, the project may not quality for authorization
under Nationwide Permit 27, in which case an individual permit would be
required.