Hatchs Hill Mit Plan Comment Response_04_12_24

April 12, 2024
Mr. Todd Tugwell
Wilmington District Regulatory Division
US Army Corps of Engineers
RE: IRT Review comments for Mitigation Plan
Wildlands Upper Neuse Umbrella Mitigation Bank
Hatch’s Hill Mitigation Site
Neuse River Basin HUC 03030201
USACE ID#: SAW-2022-00095
NC DWR # 2022-0425v1
Dear Mr. Tugwell,
Thank you for compiling and providing comments on the Hatch’s Hill Mitigation Plan. We have reviewed
the comments dated February 20, 2024, and have revised the Mitigation Plan accordingly. This letter
includes a response to each comment; comments have been reprinted with our response in bold italics.
The revised Mitigation Plan is being submitted with this letter.
MARIA POLIZZI: NCDWR
1. A detailed soil report from an LSS is required to investigate the location of hydric soils onsite.
This should be completed prior to submitting a draft mitigation plan and this information is
needed prior to submittal of the 401 application so that DWR has adequate time to review.

The detailed soils report is not required for the submittal of mitigation banks and we
have not included it. We have included a PJD with concurrence from USACE for existing
wetland delineation that allows us to calculate temporary and permanent impacts to
site waters.

2. Half of the hard copy engineering plan sheets were upsidedown. Please make sure pages are
organized properly prior to fastening as this slows down the review process. Additionally, and
this is somewhat nit-picky, but DWR prefers binder clips or other fastening methods for the
draft plan and attachments as opposed to the staple, being able to pull pages out during review
is very helpful.

Apologies. This will be rectified in future submittals and plans and mit plan will be bound
with binder clips.

3. DWR recommends using containerized saplings for supplemental planting areas. Also, it appears
that spacing will remain the same in these areas (12x6). Does this spacing account for current
trees and plants? It seems that a lower density may be warranted since the area is already
partially vegetated.

The supplementally planted areas are zones of dense Chinese privet (Ligustrum sinense)
that will not be mechanically removed and impacted by grading in construction. Instead,

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these areas are being treated with a mix of chemical and mechanical removal outside of
the limits of disturbance required for construction. The supplemental zones are primarily
forested, with native woody vegetation roughly estimated to comprise about 75% cover.
Canopy gaps will be opened in the invasive management process. The 12x6 spacing is
used as a “rule of thumb” for spacing and density in the canopy gaps. Trees will be
spaced at this density on an “as-needed” basis, accounting for the native vegetation that
remains after the privet removal. Spacing is also discussed in Section 6.7.1 of the Final
Mitigation Plan.

4. Why was 12x6 spacing selected (in general, not specifically for supplemental planting)? Is there
concern that the 6ft spacing could cause crowding as trees grow? Would a more even
distribution not be preferable?

Unlike silvicultural plantings, which often uses greater spacing, the project area will not
be anthropogenically maintained long term. 12x6 foot spacing is an industry standard
that is demonstrably effective for natural area restoration. The spacing results in
approximately 605 trees per acre at as-built. This density budgets the likelihood of
mortality during the monitoring period from transplant shock and environmental
stressors such as exposure and desiccation, extreme meteorological events, and wildlife
impacts. As an even-aged stand, it is expected that the trees will eventually compete for
spacing as the canopy closes. The planting plan includes species which naturally exist in
sub-canopy and shrub layers to further diversify forest strata as the canopy closes. As the
canopy establishes over time, trees will outcompete each other until an equilibrium is
reached between density and resource competition.

5. Is any timbering of current pine stands anticipated prior to construction? This was discussed in
the meeting minutes from the IRT site visit in 2022, but I did not see mention of it in this
vegetation section. A pine management plan was also requested at this time

The landowners have decided that pine harvest will occur concurrent with construction.
This, along with the pine management plan is discussed in Section 6.7.1 of the Final
Mitigation Plan.

6. DWR appreciates that some invasive species management has already occurred on site.

Noted. Thank you.

7. DWR does not agree that all wetlands should be classified as headwater forests. The wetland
type is very important in how WAM calculator determines score, and therefore correctly
identifying wetland types is important. Although some wetlands may be classified (correctly) as
a few different types, headwater forests are located above/around first order streams or
smaller, and therefore are not an appropriate classification across this site. Please run the WAM
calculator again with an appropriate wetland type and update associated tables accordingly. –

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The classification of Wetlands C – Wetland I was changed to Bottomland Hardwood
Forest. NCWAM forms were updated in Appendix 3 and classifications and overall
NCWAM ratings were updated in Table 4.

8. Thank you for the Inclusion of Table 7, this is helpful.
You are welcome.
9. DWR believes that the wetland enhancement ratio should be lower than 2:1 since hydrologic
enhancement is not anticipated.

The wetland enhancement ratio was discussed during the IRT Prospectus Review Site
Walk. The group discussion concluded that a 2:1 ratio was appropriate due to the
extreme severity of invasive species presence and uplift that would result from invasive
removal and establishment of a native riparian buffer. The minutes from this meeting
are included in Appendix 4.

10. Thank you for including the grading plan, this is very helpful. It does appear that there are
several locations where the >1’ cut overlaps with wetland crediting other than creation. Please
note that all grading over 1’ must be credited as creation due to the negative affect on soils and
vegetation establishment. Please update figures and credit tables accordingly.

Wetland A, located along Alpaca Creek, is an existing poorly functioning wetland. This
polygon was mistakenly shown as enhancement on the plan set and GIS figures but will
be credited as creation as discussed in Section 6.6 Wetland Design Implementation. A
small area of previously proposed re-establishment on the downstream right of the
Hatch’s Hill Lane crossing was changed to creation credit. Remaining areas of proposed
wetland re-establishment with greater than 1 foot of cut are relatively small, involve
removing soil from an anthropogenic source, and are otherwise required for P1 stream
restoration floodplain grading. A manmade berm that crosses the Lee Branch floodplain
near station 178+00 (plan sheets 1.1.18 and 5.5) will be removed and graded to the
naturally occurring floodplain elevation on either side. Other re-establishment areas with
greater than 1 foot of cut are excessive sediment deposits that formed due to the urban
and agricultural influences in the watershed discussed in Section 3.2.3. We believe these
areas are most appropriately credited as wetland re-establishment since they are
removing anthropogenically introduced stressors and do not require cutting below the
native floodplain soil.

11. DWR would like to see one additional groundwater gauge in the northern portion of the wetland
enhancement area. It is understood that hydrology improvement is not proposed, but it is still
important to monitor hydrology to ensure no negative impacts on hydrology in these areas.

One additional groundwater gauge was added in a northern wetland enhancement area.
Table 18 and Figure 12C were updated.

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12. DWR supports benthic monitoring for this project. Will water quality data also be collected at
these sampling locations?

Yes, Wildlands will follow the Standard Operating Procedures for the Collection and
Analysis of Benthic Macroinvertebrates (NCDWR, 2016), which requires water quality
data (pH, DO, conductivity, and temperature) to be sampled at the time of benthic
collection. This has been added to Section 9.0 in the Final Mitigation Plan.

13. Wetland credit boundaries approach or touch CE boundaries in many locations, which is not
preferred by the IRT. Hydrologic trespass, future landowner actions outside the easement
(ditching), etc are cause for concern in these locations. The IRT recommends a 50’ buffer around
wetland areas when possible to protect both the adjacent landowner and future success of the
site.
The wetlands on this project are bound by topography, which was evaluated using our
Civil3D grading models of the Site. South of Baker Chapel Church Road, the wetlands on
the west side of Lee Branch extend to the easement edge, which is set at the extents of
the valley bottom and at the top of the existing ditched Lee Branch. The north side also is
located within the valley bottom leaving no usable land to be drained and converted to
cropland. At the very downstream end, the wetlands extend to the easement edges as
the system begins to enter a beaver swamp with braided systems. As it is down valley
from all surrounding farming, it is very low risk of causing any impact to adjacent
properties or farming practices having impact on the wetlands.

14. Is there concern about the angle and location of the proposed confluence of alpaca creek and
lee branch (Sheet 1.1.5)? it appears that the water will be entering lee branch directly above a
meander bend, with flow directed towards the inside of the bend and creating a potential point
of instability.

The confluence between Lee Branch and Alpaca Creek orients flow from Alpaca Creek
down valley into the mainstem, which was important for a tributary of its size. The angle
between both reaches is appropriate for the size of each reach (~60o). Additionally, the
discharge capacity of the Lee Branch typical section immediately downstream of Alpaca
Creek accommodates the larger watershed size.

15. Sheets 1.1.11 – 1.1.12: there is a gap between these two plan sheets, and sta 147+50 – 150+00
are not shown. Please revise plan sheets to ensure all stations are shown (preferably with a bit
over overlap especially at crossing locations.

The gap between sheets 1.1.11 and 1.1.12 comes from the break in Lee Branch due to
Baker Chapel Church Road. The sheet set has been updated to show the road on both
sheets 1.1.11 and 1.1.12 and additional labels have been added for clarity.

16. Plan sheet 8.0: The table of large material sizing should be included for review with the draft
mitigation plan.

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A material sizing table has been added to the sheet set on sheet 8.0.

17. Is there any concern that raising the channel elevation on UT to Alpaca Creek could cause issues
with hydrology by severing the connection with groundwater? With a drainage area of 8 acres, it
seems that groundwater inputs could be a significant source of hydrology for this feature.
Loss of hydrology is not a concern on UT to Alpaca Creek. UT to Alpaca Creek is being
raised between 2 and 4.5’ from existing conditions to get the channel closer to its historic
floodplain. Nearby, Alpaca Creek is also being raised, which will promote an increased
water table within the greater valley. UT to Alpaca Creek is expected to benefit from
seeps at the edge of the proposed, graded floodplain and the sandy soils at the site will
shorten recovery time for hydrology.
Todd Tugwell, USACE:
1. It would be helpful if you would provide a narrative that discusses changes made following the
prospectus review of the project to help explain the changes to the project, including the
reduction in the length of the project at the northern end, changes to the stream approaches,
and changes to the wetland boundaries (e.g. wetland establishment and creation on Lee Branch)
and approaches. Some of this is documented in the minutes from the prospectus meeting,
however it is not clear why all these changes were made.

A discussion of the project boundary at the downstream end has been added to Section
3.2 along with photos showing the limits of backwater. Further comparison of design vs
prospectus is located in Section 6.0: Design approach overview. Stream activities match
what was proposed during the prospectus, however there is a short section at the top of
Lee Branch as it enters the site that has a Priority 1.5 transition as a result of the final
cross-section design, slope of the valley, and elevation of the culvert at the top of the
project. This is discussed further in Section 6.5.0. Wetland design follows the intention of
the final prospectus and was finalized based on the detailed topo survey, stream design,
grading plan, and wetland delineation. This is discussed in Section 6.6.

2. The mitigation plan discusses potential impacts from beaver but implies the beaver are not
currently active on the site, yet the minutes suggest that the downstream (northern) end of the
site is an active beaver system. Please elaborate on this in the existing conditions discussion and
in the adaptive management plan. What will the potential effects to the existing wetland system
just downstream of the site if beaver are trapped extensively during monitoring.

Signs of cycling periods of activity and inactivity were observed during existing conditions
assessments and using aerial imagery. It does not appear that beavers permanently
reside in this downstream wetland and within the Project area, but instead move
through the landscape. Even so, recent aerial imagery indicates ponding downstream of
the site, implying more beaver activity recently took place outside of the project area
than within. If this pattern continues, it is likely that beavers are moving upstream
through the landscape, and trapping taking place upstream in the project area will not
have a long-term effect on the downstream wetland. This topic is referenced in the

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Adaptive Management Plan and further discussed in Section 6.7.1 and Appendix 5 of the
Final Mitigation Plan.

3. It was noted during the initial visit that the site has a lot of existing pine trees that will continue
to be present immediately adjacent to the site following construction, and it was requested that
pine management be specifically addressed. Please update accordingly.

A pine management plan is discussed in Section 6.7.1 of the Final Mitigation Plan.
Existing pines will be removed during the construction phase of the project. If, over the
life of the project, the density of pine regeneration is found to negatively impact the
establishment of desirable vegetation the pines will be removed with a combination of
mechanical and chemical treatments. It is anticipated that as the canopy of installed
trees closes, loblolly pine (Pinus taeda) will be outcompeted and greatly reduced in the
project area.

4. Concerns were noted regarding the potential for encroachments, specifically where back yards
will back up to the easement, but this was not specifically addressed. Given this, do you think
the proposed endowment, which allocated only $65/year to address minor violations (1 per 10
years) is sufficient?
The easement boundary abutting residences in the southwestern portion of the project
will be bound by fencing offset from the easement boundary by 1 foot. Signage will be
posted at each boundary corner and at a maximum of 100 feet apart. The couple houses
on the southeastern portion of the project adjacent to Baker Chapel Church Road will be
marked with sign posts at a frequency of 100 feet and have polytape to reduce
probability of mowing encroachments. The Gragg residential parcel on the north side of
Baker Chapel Church Road also abuts the easement and is partially mowed. This parcel
will be well-demarcated with signage at a maximum of 100 feet apart or closer as
necessary to ensure signs are within line-of-site of each other. Polytape will be promptly
installed if mowing encroachment appears to be a high risk. At this time the Graggs are
cooperative partners and understand the proposed limits of the easement boundary.

UP2Save has been to the site and walked it and is aware of all potential maintenance
needs. They have done their own calculation for the funds required for their endowment.

5. The above (and other) concerns should be specifically addressed in the adaptive management
plan, which is overall lacking in any detail regarding potential issues the site may encounter.
More information can be found in the District’s adaptive mitigation plan guidance available on
the RIBITS website.

Further discussion of the above and other land management concerns are addressed in
Section 6.8 and Appendix 5 of the Final Mitigation Plan. Section 11 Adaptive
Management Plan references these sources of information for further details.

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6. During the prospectus review, the IRT requested that wildlands conduct a study of the
contributing watershed to understand how much is in a pipe network vs open channel and
explain how this would affect hydrology and hydraulics as well as sediment delivery. Was this
completed, and if so, please include a discussion of this analysis in the draft plan.

Wildlands conducted a Watershed Assessment to determine how stormwater pipes
might affect the hydraulics, hydrology, and sediment delivery of the Site. There is a 5’ H x
6’ W box culvert at the upstream extent of Alpaca Creek that will limit the peak
discharge coming into the reach (see 3.2.0 Existing Streams). Several stormwater pipes
were found that drained areas east of Hwy 117 increasing drainage areas of Lee Branch,
Alpaca Creek, and Jackson Creek by 0.14, 0.07, and 0.15 square miles, respectively. A
drainage ditch and 24” RCP were discovered at the upstream end of UT Alpaca Creek
that convey flow to Lee Branch, decreasing the drainage area by 0.001 square miles. All
watersheds were revisited from Prospectus values using LiDAR data. Watershed changes
are discussed in section 3.0 Watershed Conditions. Additional areas provided by the
stormwater pipes do not include sources of increased sediment delivery to the system.
Sediment delivery and transport is discussed in section 6.4 Sediment Transport Analysis
of the Mitigation Plan.

7. The IRT requested a flow gage on Lee Branch, but it does not appear to be in the draft plan.
Please update the monitoring plan accordingly.

A flow gauge was added on Lee Branch. Table 18 and Figure 12B were updated.

8. Section 7 discusses credit determinations and proposes a 2% increase for benthic monitoring.
Please not that the 2% associated credit increase for additional monitoring (not tied to
performance) assumes both macroinvertebrate monitoring and water quality monitoring will be
conducted (reference the 2016 District monitoring guidance, Sec VII). Please elaborate whether
water quality parameters will also be monitored per the guidance.

Yes, Wildlands will follow the Standard Operating Procedures for the Collection and
Analysis of Benthic Macroinvertebrates (NCDWR, 2016), which requires water quality
data (pH, DO, conductivity, and temperature) to be sampled at the time of benthic
collection.

9. The project proposes to utilize the non-standard buffer guidance to assist stream credits;
however, this method cannot be used on only a subset of project streams. If you choose to
apply this method, please conduct an assessment of all project streams, including those to the
south of Baker Chapel Church Road. Additionally, please separate the ideal and actual buffer
maps into two separate maps for clarity.

Wildlands has chosen no longer use the buffer tool on this project. Wildlands met with
USACE on March 22, 2024 virtually to discuss. As a result of that discussion the easement
on the northern side of the project has been reduced. This reduction is reflected in all

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project figures, planting, and construction plans submitted with this project and will be
reflected in an updated plat submitted to USACE.

10. Was consideration given to a wetland buffer? Particularly where wetland rehabilitation or
enhancement or creation areas extend to the CE boundary? Wetland reestablishment is
proposed along much of Lee Branch that extends all the way to the CE. The mitigation plan
notes that the project has been designed to prevent hydrologic trespass; however it is not clear
how wetland areas that have increased hydrology will not extend outside the CE boundary
where they abut the CE, particularly in areas that are flatter inslope. Even if the CE is located at
the edge of the proposed wetland reestablishment area, how can we ensure future drainage
ditches constructed just outside the CE won’t impact wetland function.

The wetlands on this project are bound by topography, which was evaluated using our
Civil3D grading models of the Site. South of Baker Chapel Church Road, the wetlands on
the west side of Lee Branch extend to the easement edge, which is set at the extents of
the valley bottom and at the top of the existing ditched Lee Branch. The north side also
encompasses the valley bottom. At the very downstream end, the wetlands extend to
the easement edges as the system begins to enter a beaver swamp with braided
systems. As it is down valley from all surrounding farming, it is very low risk of causing
any impact to adjacent properties or farming practices having impact on the wetlands.

11. I appreciate the inclusion of reference streams associated with the project but did not see any
discussion of reference wetlands. Have reference wetlands been identified for this site? are
reference streams and wetlands proposed to be monitored during the project monitoring stage
as well?

We did not identify a reference wetland for this Site and we do not plan to monitor
reference streams or wetlands.

12. Appendix 6 is missing from the draft plan.

Apologies. It has been included in the Final Mitigation Plan.

13. The draft conservation easement includes a revision that states “however, it is acknowledged
that Grantee shall be included in and considered the lead entity in all enforcement activities
conducted by the Coprs, NCDWR and Bank Sponsor” it is our expectation that the Grantee will
take an active role in enforcement, however, I am concerned that this language would be
misinterpreted to suggest that the Corps’ right of entry is ceded to the Grantee, which we
cannot do. I suggest the removal of the words “and considered the lead entity in” from this
statement.
The words “and considered the lead entity in” have been removed.

If you have any questions please contact me at [e-mail], [phone] x 106.

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Sincerely,

Angela Allen, PE
Project Manager