Riverbend Crediting Memo_Response to IRT Comments

WO.*
WILDLANDS
E N G I N E E R I NO
January 9, 2023
RE: Response to NCIRT comment on the Riverbend Mitigation Site Crediting Adjustment Memo
Riverbend Mitigation Site
Catawba County, NC
USACE Number SAW-2021-02608
NCDEQ Contract Number 210102-03
DMS Project Number 100592
Catawba River Basin 03050102
This memo documents NCIRT's comments (in italics) received from Kim Isenhour's email dated
11/10/2022 and the project team's responses (in blue).
1. Please provide a lidar map in the draft mitigation plan to help justify the stream alignment of UT2.
A Lidar Map will be included in the Draft Mitigation Plan
2. The stream relocation will likely impact existing wetlands; account for this in the permit application.
Proposed stream channels (from left top of bank to right top of bank) will be reported as
permanent impacts to existing wetlands that are delineated in the approved jurisdictional
determination.
3. Please ensure that no wetland credits overlap with the newly relocated stream channel.
We will ensure that no wetland credits overlap with the proposed stream channels submitted
with the draft mitigation plan.
4. Please make sure that you have sufficient wetland gauge coverage of all areas, including the
enhancement areas where you are proposing ditch and stream work will help improve wetland
function.
Uplift within wetland enhancement areas (Wetland Area 2 and 3) includes cattle exclusion, invasive
vegetation removal, and protection via conservation easement. These areas currently have a
consistent hydrology source and substantial improvements to hydrology are not expected due to
stream and ditch work. A wetland gage has been installed in Wetland Area 2, but a gage was
deemed not necessary in Wetland Area 3. A total of ten (10) wetland gages have been distributed
throughout the Site
5. We request the placement of a stream flow gauge where restoration transitions from an ephemeral
ditch to a perennial stream.
A flow gage will be placed in this location in the near future.

6. Please provide justification why the confluence of UT2 and UT to SF was shifted downstream from
the original proposal. Are there any concerns with parallel channels within a generally flat area?
The original proposal did not include UT2 as a stream. Proposal Site walks identified the stream as a
ditch and it was not proposed for any streamwork. UT2 was added as part of the preliminary
jurisdictional determination field work after the post contract IRT meeting. The confluence of UT1
and UT to SF Catawba was moved downstream to better match the existing flow paths at the Site.
Multiple drainage points enter the low sloped floodplain and it is not uncommon for sinuous
channels to run adjacent prior to confluence in stream and wetland complexes such as these. Figure
6 illustrates the changes in stream alignments in relation to the existing stream channel locations.
Note that stream alignments depicted are concept alignments and may change with more design
analysis, topographic and hydrologic data. Slope and sediment considerations will be evaluated
during design to determine the most functional locations of the stream alignments based on
proposed valley and wetland grading.
7. Please provide some discussion why the stream design changed so much due to the UT2 JD.
The stream alignments depicted are concept alignments and may change with more design analysis,
topographic data, and hydrologic data. The original concept alignment of UT to SF Catawba was
drawn to interact with more of the wetland areas along the Wetland Area 1 ditch system. With the
addition of UT2 as a restored stream to the design, the concept alignments were moved closer to
the existing stream alignments at the Site.
Enclosures:
• Figures
o Figure 6 — Concept Map with LiDAR relief
WiIdIan ds Engineering, Inc. (P) 704.332.7754 • 1430 South Mint Street, Suite 104 • Charlotte, NC 28203

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