Draft Mit Plan Comment Memo_NCDMS Dirty Boots_SAW-2022-02401

DEPARTMENT OF THE ARMY
WILMINGTON DISTRICT, CORPS OF ENGINEERS
69 DARLINGTON AVENUE
WILMINGTON, NORTH CAROLINA 28403-1343

CESAW-RG/Haywood June 21, 2024

MEMORANDUM FOR RECORD

SUBJECT: Action ID. SAW-2022-02401, NCDMS Dirty Boots: Comments from 30-day
NCIRT Mitigation Plan Review, Chatham County, NC

The comments listed below were received from the NCIRT during the 30-day comment
period in accordance with Section 332.8(d)(7) of the 2008 Mitigation Rule. The 30-day
comment deadline is April 30, 2024.

Maria Polizzi, NCDWR (NCDWR #20221571):

1) If possible, please include buffers around wetland credit areas to minimize risk of
hydrologic trespass and/or future landowner actions that may degrade the
wetland hydrology. If buffers cannot be provided, please provide more detail
about why hydrologic trespass is not expected to be an issue and/or how it will
be handled if it becomes one.
2) Could crossing 2 be relocated upstream of the wetland reestablishment area?
Additionally, please consider using culverts that convey at least a ten-year storm
event. Designing crossings for long-term stability is important in order to reduce
the need for future maintenance. DWR is also concerned about the potential
negative effect of the crossings bisecting the proposed wetland reestablishment
area.
3) All existing wetlands are described as headwater forest on the WAM forms. DWR
questions whether Headwater Forest is an appropriate wetland type for all
locations. Although the additional detail about the WAM forms in Section 3.4.1 is
appreciated, DWR would recommend using the available knowledge of the site to
inform WAM classifications and not limit 0 and 1st order stream determinations to
data from the USGS topographical map. This report describes UT3 (not shown
on USGS) as jurisdiction which would mean that Dirty Boots downstream of UT3
is a second order stream based on the information known about the project.
Headwater forests are also typically located on the upstream extent of a
particular stream feature. Although it seems likely that WAM scores for project
wetlands will still be low in most cases, as described, I wanted to bring up this
discussion since the classification of the wetland is important in how the score in
calculated in the WAM tool.
4) It appears that wetland impacts may result from crossing 1. If correct, this should
be noted in Section 5.1, as it currently reads as if wetland impacts only result
from stream restoration activities and realignment.
5) DWR wonders whether wetland A should be enhancement rather than
rehabilitation. With groundwater data showing 36.7% of the growing season
consecutively above the 12” water table depth, it seems like uplift will be primarily
from livestock exclusion and revegetation efforts.
6) Please include a permanent vegetation plot in the drained pond area.
7) Please include an additional set of cross sections upstream of crossing 2 on
UT2.
8) Please include the following vegetative performance standard: No single planted
or volunteer species shall comprise more than 50% of the total stem density
within any plot.
9) Historic aerials: In the future, please consider including property boundaries or
CE boundaries on historic aerials. Although it is simple enough to identify specific
locations for this project, sometimes it can be quite challenging, especially if the
landscape is more uniform.
10) Are impacts to preservation wetlands along UT3 anticipated as a result of bank
grading and stabilization? What impacts to vegetation are anticipated along UT3
Reach1?
11) How dependent are the UT3 Reach 1 wetlands on the pond, as a source of
hydrology? Is there concern that these wetlands may lose hydrology or shrink
once the pond is removed?
12) Would it be possible to incorporate a more varied stone sizing into the riffle
material, especially for smaller streams? DWR is concerned that with Class A
and B rip-rap being the only stone sizes included in the design, the bed material
may be unnaturally large. Based on the Table 14 (pg. 16) it appears that the
movable particle size is significantly smaller than the design D50, so it seems
that there may be some wiggle room. Additionally, it appears that the existing
particle size distribution is much smaller than that of the proposed channels.
However, I am not an engineer, so feel free to provide additional justification if
WEI feels that this is necessary for the success of the design.

Travis Wilson, NCWRC:

1) I have reviewed the draft mitigation plan for Dirty Boots. Overall the plan looks
adequate but I do have a couple of comments.
a. I was glad to see individual crossing details included in the draft plan. The
details include appropriate design considerations for inlet and outlet
inverts as well as backfill specifications that will aid in promoting Aquatic
Organism Passage. However, there was no reference to the details on the
plan sheets. Plan sheets with a crossing should include a reference to that
crossing’s detail.
b.Outlet stabilization: WRC understands the need and benefit of outlet
stabilization for culverts; however, more specific information should be
included in the detail. As shown, this could be a riprap dissipater pad.
Outlet stabilization should be embedded with the intent to armor the
stream bed. Specifically, it should be embedded to tie into the elevations
of the material in the embedded culverts. This approach will provide scour
protection, allow low benches to form on the higher outside culverts and
promote AOP. Sills are located downstream of all the crossings; however
it appears there will be a gap between the scour protection and the
downstream sill. Setting a sill out the outlet of the armored scour pool may
better promote long‐term stability and AOP.
Emily Dunnigan, USACE:
1)Please add photo points to all crossings and the proposed BMP. Please include
the BMP on the monitoring map.
2)Please add a fixed vegetation plot to the pond dam footprint.
3)Some areas of wetland credit are not represented by gauges. Please add at least
3 groundwater gauges to the right bank side of Dirty Boots Reach 1, Dirty Boots
Reach 2, and UT3 Reach 2.
4)Please add at least 1 cross section to UT2 Reach 1.
Casey Haywood, USACE:
1)To confirm, is the BMP on Dirty Boots Reach 1 located in an existing wetland?
Please note that it is not appropriate to install BMPs in jurisdictional features. The
area appears to be an existing wetland (Wetland E) on Figure 2 and is also called
out in on the Jurisdictional Determination map (Appendix 4, Figure 3). Is wetland
rehabilitation or enhancement more appropriate here? Also, I was trying to find it
in the notes, but I’m curious why the area was not included as part of the project?
The stream form for UT to Dirty Boots was provided in Appendix 3. Will cattle still
have access to Wetland E outside the easement?
2)Concur with DWR’s comment #5. The groundwater gauge in Wetland A is already
meeting well above the performance standard (likely from the downstream beaver
dam). Is the location of GWG 3 representative of the entire area proposed for
rehabilitation? Wetland enhancement is more appropriate if functional uplift is
limited to planting and cattle exclusion.
3)Is the origin on UT2A captured? It looks like it originates just outside the easement
on Figure 8. Is it possible to include it in the project? With the origin point starting
just outside the easement, and the length of the reach being approximately 80 LF,
there is concern that future land use could impact the reach given how small it is.
4)Section 6.7- Please update to reflect that Wetland I (not J) was changed from
preservation to enhancement. The labels for the existing wetlands on Figure 2
need to match the JD. Please update the document as needed and verify credit
totals.
5)Figure 9 Monitoring Components:
a. Please add photo points to the crossings and BMP. Also recommend adding
photo points to the tops of the reaches.
b. There needs to be a fixed vegetation plot in the pond bed. Please also have
a random veg plot capture the area below the pond at some point during
monitoring given the grading sheet indicated 3’+ cut on UT3 R2.
c. When installing additional wetland gauges, please install a gauge in the
wetland rehabilitation area adjacent to UT3 Reach 2/Dirty Boots Reach 1.
d. Will a rain gauge be installed at the site? If not, please identify the proposed
rainfall data source location and distance from the project site. The IRT
strongly encourages an onsite gauge.
e. Please add a cross section to the upper section of Dirty Boots Reach 1
(within the wetland enhancement area). The November 2022 site visit
meeting minutes indicated the IRT was concerned that dense wetland
vegetation could overtake the channel.
f. A cross section or photo point needs to be added at the southern end of
Dirty Boots (Reach 2) to help monitor any impacts from the beaver dam
downstream.
g. Recommend including planting zones on the map. WEI had another recent
DMS project submission that included the planting zones and it was very
helpful for our review.
6) Appendix 5: Appreciate the Categorical Exclusion summary provided in the report.
It would be helpful to include the IPaC Species List letter from USFWS as
supporting documentation. The letter is also important because it includes the
USFWS project code that we would have to refer to if we had to coordinate with
the Service for the permit.
7) Design Sheets:
a. Thank you for providing the Grading Cut and Fill Exhibit. As mentioned
previously the BMP on Dirty Boots Reach 1 should not be installed if it is an
existing wetland. Please be sure to update this figure so that the existing
wetland is not impacted by a 2-3’ cut.
b. Please add LOD to the design sheets to ensure there are not impacts to
aquatic resources outside the project area as mentioned in Section 5.

Casey Haywood
Mitigation Project Manager
Wilmington District

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