20200775 Ver 1_Middendorf Springs_100151_Response to IRT Comments_7-19-2023

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
Page 1 of 10

531 N. Liberty St. + Winston-Salem, North Carolina 27101 + 336-790-6744 + FAX [phone]

July 19, 2023

Steve Kichesfski
U.S. Army Corps of Engineers
Regulatory Division
Raleigh Field Office
3331 Heritage Trade Dr, Suite 105
Wake Forest, NC 27587

Re: DMS Project ID # 100151 / Middendorf Springs Stream and Wetland Mitigation Site Mitigation Plan
IRT Comments

Dear Mr. Kichefski:

Freese and Nichols, Inc. appreciates the Interagency Review Team’s (IRT) thorough review of the project. We
have addressed all comments provided by the IRT on May 24, 2023 for the Middendorf Springs Stream and
Wetland Mitigation Site Draft Mitigation Plan. As requested in that letter, we are providing our proposed
response to the comments prior to proceeding with the Final Mitigation Plan. Our responses are in blue
below:

Comments received (Black Text) and Responses (Blue Text)

David McHenry, NCDWR:
I’ve reviewed the plan and don’t have any comments to offer. Thanks for the opportunity.

Thank you for reviewing the document.

Olivia Munzer, NCDWR:
1. Page 58, Section 7.5. It appears a word at the beginning of the sentence on line 10 is missing - probably
“Table 15”.

Thank you. The text has been updated.

2. On Sheet DT-8 Planting Plan, they have hard fescue on the list – this is a non- native species, and it
likely will outcompete the native species. It should be replaced with a native species. Also, the Woody Planting
list on this page is difficult to read.

We appreciate you pointing out this that species was accidentally included on the list. We would not
suggest fescue on a restoration project. Hard fescue has been removed from the list.

Mac Haupt, NCDWR:
www.freese.com

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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1. DWR appreciates the review (and extensive comments) from Kelly Phillips of DMS.

2. DWR would like to emphasize the comment on the DMS review of Sheet C-2. DWR has concerns over
the extensive use of Angled Log Sills on some of these streams with the slopes present.

We appreciate the comment. We are not concerned with the use of angled log sills as noted in the plans
because we have had great success with this structure when it is being implemented by an experienced and
qualified contractor and with experienced construction oversight. We have included experienced and
qualified contractors as potential construction partners. Additionally, we will have qualified staff at the site,
particularly during the initial in-stream construction of the logs, to ensure that the contractor understands
our detail and design goals and that these structures are structurally sound upon construction with respect
to detailed drop distance and installation of filter fabric to prevent undermining of the structure (as noted
in comment #12).

Based on our experience with log sills, instability of the angled log sills typically occurs because the step drop
is too great or there is insufficient filter fabric or filter stone behind the logs. We have added clarity to the
detail to indicate that the step drop is to be 6” with an allowable tolerance up to 8”.

One other issue with the extensive use of angled log sills (or any log structures) that was not mentioned in
the comments is the potential for decay of the logs due to wetting and drying of the logs. Streams in the
Slate Belt region are known to become dry in the summer. Thus, in the Slate Belt region there is concern that
the wetting and drying of the logs would lead to a faster rate of decay than when the logs would be
consistently wet. However, we are not concerned about this issue on the project for several reasons. As
explained in the response to the next comment, the groundwater hydrology of the site is not typical of the
Slate Belt due to the presence of the Middendorf formation at the ridgeline above the project streams,
providing a more continuous supply of groundwater and baseflow from the numerous springs present across
the site, which will help keep the log sills consistently wet . In addition, we have also proposed constructed
riffles along with the logs sills which will provide long-term stability to the channel even if the log sills begin
to decay over time.

3. Table 4 (and Section 3.3.1): DWR has concerns over the flow (because of the small drainage areas and
slate belt geology) for the following tributaries; 1B, 1C and trib 5.

FNI designers have extensive experience with stream restoration design in the Slate Belt and great familiarity
with the hydrology and geology of this region. Our lead designers have successfully implemented several Full
Delivery projects in this physiographic region with full release of credits. As noted in the mitigation plan, the
geology of the site is unique and not typical Slate Belt geology. While streams located in the Slate Belt are
known to dry up in the summer, the presence of the Middendorf Formation (marine sands and clays) at the
ridge above the stream origins appears to act as a mini aquifer that creates springs across the site where it
contacts the slate belt mudstone unit below. This supplies a much more continuous source of baseflow to
the streams than we’ve seen in other small drainage-area Slate belt systems. We have documented the
project streams continuing to have baseflow well into “abnormally dry” and drought periods. Based on this,
we are confident that the stream will meet the minimum 30 days of consecutive flow that is required for the
site. Our mitigation plan includes proposals to monitor baseflow using pressure transducers or game
cameras on particularly small reaches where the transducers would be less effective.

4. Section 3.3.2.2- Hydric Soils Investigation- DWR was appreciative of the fact there was a Hydric Soil
report by a Licensed Soil Scientist; however, the hydric soils report in Appendix E has several

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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shortcomings. As was stated in the report, “Due to time constraints, the hydric soil investigation was
not a complete review of the entire area…”. The review lacked covering the entire project area, lacked
geolocating the borings on a map, and should have included many more borings given the wetlands
that were evidently present.

The licensed soil scientist was tasked with studying and documenting the hydric soils within the proposed
easement, not the entire property parcel. The statement is made to note that the entire property parcel
(outside of the proposed easement) was not studied. The licensed soil scientist did investigate and cover
the entire easement area including the areas of proposed wetland restoration areas.

5. Section 7.2.1- Stream Restoration Approach- DWR cautions raising a small drainage area stream in the
slate belt region. DWR believes that there will be continuous flow issues on most of the streams in this
project.

Please see our response to DWR Comment #3.

6. Table 12- Shows that the D50 proposed metric is to be 101.6 mm, or about 4 inches. Seeing the typical
for the constructed rifle, of which there will be many on this stream, DWR noted the use of Class A rip
rap in the typical. DWR believes that this will result in a considerable “hardening” of the stream
channel. DWR does not support the extensive use of class A rip rap in these stream channels.

The note to use “Class A” rip rap on the typical was only to communicate the standard size range needed for
the proposed bed material in the constructed riffle and not on how the stone should look. The size was
determined from calculations of the bed material size needed to create an immobile bed appropriate for a
threshold channel, as discussed in the mitigation plan. We agree that the appearance of typical Class A rip
rap would not be appropriate for the site, and therefore plan to source stone for the constructed riffle areas
from a local slate quarry. FNI staff have used this same quarry and its rock for another DMS full delivery
project. This material has the textural features, shape and appearance typical slate belt stream bed material
and therefore will look more appropriate for these stream channels.

7. DWR appreciates the design firm utilizing the wetland performance criteria of 12% hydroperiod during
the growing season.

Comment noted.

8. Section 9.5- DWR will require three additional gauges be placed in existing wetlands to ensure that the
constructed stream channel does not significantly reduce the wetland hydroperiod. The specific areas
will be mentioned in the review of the Design sheets.

The comment has been noted, and appropriate gauges and number of gauges will be installed in order to
document project success. The mitigation plan will be updated accordingly to note this.

9. Figure 7. It would have helpful if the drainage area acreage would have been listed on the map.

Figure 7 has been revised to include the drainage area acreage.

Figure 11- Proposed Mitigation Plan-there are several areas of concern on this map. First of all, DWR urges the
designer to capture all areas that connect to the easement that may affect either the stream or wetlands.
Examples of these areas which will likely affect the streams include the headwaters of tributaries 1C, 1B, and 4.

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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In addition, there are several areas (proposed wetlands A and B, and existing wetlands, WF, WH, and WA)
where the easement line is directly on either proposed wetlands or existing wetlands. In the past the IRT has
encountered problems where wetlands just outside the easement line were ditched by the landowners and of
course these ditches affected the wetlands within the easement. Also, tributaries 5 and 6 both are shown to run
down valley from where they initially had their confluence with the stream. Figure 14 is offered for evidence for
tributary 5’s path, however, DWR did not note any support for tributary 6’s path.

The reviewer has detailed several items in this one comment, and our response will attempt to
systematically address each of the comments that were raised.

The reviewer has asked that FNI capture areas that connect to the easement that may affect either the
stream or wetlands. After further review of this comment, we have elected to expand the conservation
easement to capture additional wetland areas at the head of Tributaries 1B and 1C as well as in other
locations noted in the reviewer’s comment. The wooded wetland areas upstream of the current
conservation easement boundary on Tributary 1B and 1C will be included in the new easement area.
Additionally, several areas where the proposed conservation easement skirted close to an existing wetland
boundary have been moved out somewhat to provide additional distance from the existing wetlands to the
proposed easement boundary (e.g., Wetlands WP, WD and WN). We have attached a figure to this response
letter depicting the approximate areas of expansions of the easement. However, we are not concerned about
ditching from the landowners affecting either existing or proposed wetlands because the proposed
conservation easement will block the landowner from being able to outlet the ditch anywhere on the
property. If the landowner were to install ditches adjacent to wetlands in the easement, such an effort
would be futile as the ditches would be parallel to the area and, to make a ditch, there would have to be a
place where the ditch can outlet. There would not be anywhere to ‘outlet’ the ditches because FNI has
already included all potential outlets of a ditch into the conservation easement.

In regard to extending the conservation easement further up Tributary 4 to its origin, this is not a practicable
option as the mitigation credits needed in this contract have already been supplied based on the proposed
restoration areas and conservation easements shown in the mitigation plan. With Tributary 4, a logical,
upper limit breakpoint was established at the point where there was already an existing culvert (to be
removed). As noted above, we don’t believe Tributary 4 will be at risk of undercutting or being affected
upstream of the easement because drainage cannot be ditched deeper nor modified. Our rationale is that a
new drainage feature would have to connect into the restored channel. Given the constraints on the site,
we don't believe that such an action is a reasonable threat. However, we will update the mitigation plan with
additional detail of these potential risks and uncertainties.

We will provide additional documentation on the proposed pathway/alignment of Tributary 6 similar to
what was submitted for Tributary 5.

10. Figure 12- Monitoring Plan- DWR believes there should be flow gauges in the upper third of the reach
on each of the reaches proposed for restoration or enhancement work. Tributary 1B does not show a
flow gauge.

Comment noted. We will add this to the mitigation plan.

11. Design sheet- C2-there is a lot of slope in this section with a lot of log sills. In the past, log sills have
shown to be prone to leak or lose the ability to hold grade. Careful oversight will be needed in the

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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construction of so many log sills. Moreover, DWR requires a gauge in the existing wetland placed
stream right approximately near station 4+50.

See response to DWR Comment #2 where we attempt to address all of DWR’s concerns about the angled
log sills. Oversight of the log sill construction will be performed by experienced and qualified personnel.

Comment noted with respect to the additional gauge and this will be added to the mitigation plan.

12. Design sheet- C5 - DWR requires a wetland gauge stream right near station 2+50. This section shows a
lot of constructed riffles. DWR would like to emphasize their concern of placing rip rap in the stream
channel. DWR suggests the designer look for a source of rock on site that more resembles native rock
on site both in type and in size for the stream. In addition, DWR noted that there does not appear to be
any bank treatments for the meander bends. How does the designer intend to maintain the stability of
the stream in these areas (Design sheet C6)?

Comment noted with respect to the gauge and this will be added to the mitigation plan.

See response to DWR Comment #6 regarding rock selection for the constructed riffle section.

With respect to the meander bend question, we ask that the commenter consider the size of the stream
channel that is proposed. Based on our calculations, shear stress on the outside bend is not high. The site’s
drainages are small channels, and the installation of a bank stabilization treatment like toe wood or similar
treatment would be very large considering the channel size and overwhelm the small channel, potentially
affecting the pool size and function and creating instability issues rather than helping with stability. However,
to address concerns over the stability of the meander bends we will increase the planting density on the
banks.

13. Design sheet C7-same comment as #12 regarding slope and log sills.

See response to DWR Comment #2 where we attempt to address all of DWR’s concerns about angled log
sills.

14. Design sheet C9- in the longitudinal plot there were no lines.

We checked Sheet C-9 in the PDF version and the longitudinal plot lines are showing up correctly. It is
possible that if you were reviewing a hardcopy that the lines may have printed out too faint to see. We will
double check the plot hardcopy and adjust as necessary to make sure the lines are showing up.

15. Design sheet C16- DWR requires a gauge stream right at approximately station 4+50.

Comment noted and we will add a stream gauge to the mitigation plan at that location.

16. Design sheet DT3 – DWR requests the on-site construction supervisor emphasize the specs of the log
sill rollers with the construction company and specifically emphasize placement, footer logs and the
minimum amount of length the log embedded into the bank.

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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See response to DWR Comment #2 where we attempt to address all of DWR’s concerns about angled log
sills. We will emphasize the requested items with the construction contractor.

17. Design sheet DT4- DWR requests the designer look for rock on site which will be more suitable for the
stream rather than using NCDOT Class A rip rap.

See response to DWR Comment #6.

Casey Haywood, USACE:

1. Pg 10 Section 3.3.1.1 - Is the condition of UT1A Upper and Lower the same? Recommend discussing
the characteristics of existing conditions separately for these sections. UT1A Upper appears stable in
the photo provided in the photolog. It would be helpful if the photos in Appendix L were moved to the
narrative to help add context.

The conditions of the two reaches of UT1A are not the same. UT1A Upper is more stable than UT1A lower.
Although it is still incised it does possess more stable banks and mature trees on its bank which provide
stability and are limiting the degree of bank erosion. We will break out the discussion to describe these
reaches separately. We will move the photos to the narrative to help add context to the discussion.

2. Pg 17 Section 4.1.5- Section stated that improvements to biological activity will be noted during visual
assessments. Unless macrobenthic sampling will occur and/or visual observation data of biological
activity will be collected, recommend removing this statement.

We have removed this statement about visual assessments of biological activity.

3. Pg 19 Section 5.5- Stream relocation is estimated to impact existing wetlands within the easement.
Section 5.5 and 7.2.6 mention how permanent wetland impacts will be offset by stream restoration
activities and planting of existing (but unimpacted) wetlands. Is this quantified somewhere for a
comparison against wetland loss? Though it is anticipated that the total wetland acreage, and quality,
will likely increase as a result of stream restoration, the Corps must still ensure that there is no net loss
of wetlands as a result of ecological restoration. If you do not plan to install gauges on all wetlands
within the easement and monitor hydrology, please plan to reverify the extent of jurisdiction at the end
of the monitoring period to document that wetland acreage was not lost.

While we did include a table of estimated acreage of temporary and permanent wetland impacts, we did
not include a direct comparison of wetland loss versus wetland gain in the mitigation plan but we will add
this. We will add language regarding re-verification of jurisdictional status at the end of the monitoring
period.

a. Please be sure to include temporary and permanent impacts to both streams and wetlands
when submitting the ePCN along with an impact map. Additionally, any work being done outside the
easement boundaries, where you propose to tie into existing channels/ditches and upgrade or install
culverts, need to be included in the ePCN impacts. For instance, the 48” culvert crossing on UT6
(Figure 11) located just outside the easement is tied to the project and will need to be included on the
impact table unless a separate NWP14 will be requested. Any crossing impacts you believe qualify as
agricultural exemptions should be clearly reported with location, impact length, culvert size, etc. so the
proper determination can be made.

Middendorf Springs Stream and Wetland Mitigation Site Response to DMS Comments
July 17, 2023
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Comment noted, and the appropriate documentation for required permits will be submitted.

b. Please see the attached Permitting Tips for Mitigation Sites PDF for reference and update the
Mitigation Plan as needed.

Thank you for including this in your comments. We have reviewed and will update the mitigation plan as
needed based on this document.

4. Pg 25 Section 7.2.1- While much of the work on the PI Restoration reaches are similar, this would be a
good opportunity to discuss the stream design implementation for each individual reach such as the
road relocation and culvert installation at the top of UT4 and UT6.

We will add more detail regarding the stream design implementation for each individual reach in this
section per your comment.

5. Pg 27 Section 7.2.3- Appreciate the inclusion of Figure 14 to justify the location of tributary 5. Please
include similar documentation for tributary 6.

A similar figure has been developed to justify the location of Tributary 6 and added to the mitigation plan.

6. Pg 28 Section 7.2.7- A treatment marsh is proposed at the top of UT4. It is understood that this was
discussed with the IRT; however, if this area is currently jurisdictional it is not appropriate to place a
BMP in a jurisdictional feature. It appears that this area is called out on the JD maps and Figure 9 as a
perennial stream. Please confirm. Would there be an option for a BMP or marsh treatment area above
UT2?

FNI agrees with the comment regarding the treatment marsh at the top of UT4. This has been removed.

With respect to UT2, a spring-fed wetland already exists at the top of this feature. Therefore, no BMP or
marsh treatment is needed.

7. Pg 32 Section 7.5- The selection of plant species is based on species present in the forest adjacent to
the site, please add a brief description of the vegetative community used for reference.

This has been added to the mitigation plan.

8. Pg 32 Table 15- The percentage for Sycamore seems high. It would be preferable to reduce the percent
of Sycamore.

We have reduced the percentage of sycamore by 5% in the planting table and have adjusted the other
species accordingly.

9. Section 7- Was any information gathered from a wetland reference site to help develop project target
conditions?

No data were specifically gathered from a wetland reference site. A review of existing wetlands at the site
informed our decision making with respect to the project’s target conditions for the restored wetlands.

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July 17, 2023
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10. Pg. 33 Section 7.6- What is the potential for hydrologic trespass onto adjacent fields? While there have
been discussions with the landowner, there is no way of ensuring that the LO will not construct new
ditches immediately adjacent to your project that would result in drainage of wetlands restored on your
site. With no guarantee that the adjacent parcel will not be transferred to a different landowner in the
future, this potential site constraint should be discussed in the text.

We appreciate the commenter’s concern for the long-term protection of these areas. Please see our
response to DWR Comment #9 regarding the potential for impact to the restored wetlands by adjacent
ditching. We will include more discussion regarding this potential site constraint in the text.

11. Pg. 33 Section 7.6- It was noted in Section 3.1.1 that cattle are located on adjacent parcels upstream of
Tributary 1. Do the cattle have access to the wooded buffer on Tributary 1A outside the easement or
are they fenced out? If so, add a discussion of potential issues that could arise on the Site from the
cattle access upstream. Noted that the Site does not propose any fencing.

There are no longer cattle being grazed on this adjacent property. The adjacent property has been sold,
and poultry houses have been constructed on the land. We have revised the mitigation plan to reflect this
change in land use.

12. Pg 38 Section 8.3- Please note that volunteer species must be present for at least two growing seasons
before counting toward meeting performance standards for monitoring year five and seven.

Comment noted. We have revised the mitigation plan to reflect this.

13. Pg 38 Section 9.0- Is that the “weather station” shown on Figure 12 the on-site rain gauge? There was
no mention of a rain gauge in this section.

Yes, the weather station includes a rain gauge. We will revise the mitigation plan to note that the weather
station also includes a rain gauge.

14. Pg 39 Section 9.4- Indicates cross sections will be installed on all Restoration and Enhancement I
reaches however, there is no cross section shown on the EI reach on Figure 12.

An appropriate number of cross-sections will be added to enhancement reach on Figure 12.

15. Figure 5: Please include the proposed easement boundary.

The figure has been revised to include the proposed easement boundary.

16. Figure 7: Please show drainage area acreages on the map.

The figure has been revised to include drainage area acreages on the map.

17. Figure 9- Please indicate the location of the perimeter ditch to be filled (as shown on the map in
Appendix A).

The figure has been revised to include.

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July 17, 2023
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18. Figure 11-

a. It’s unclear in the figure, text and design sheets where culverts will be replaced, in particular for
the road relocation above Tributaries 4 & 6. These crossings were discussed during the IRT
meeting. Please call out these locations on the figure and discuss in further detail in the narrative.
Does the road go through the top of the CE on Tributary 6? The line for the proposed reroute
appears to stop at the easement line but the note suggests it will be located above the easement.
Design sheets should also be updated accordingly.

The road will not go through the Conservation Easement on Tributary 6 but will be routed to the north
upstream of the conservation easement. We will update the figures, mitigation plan narrative and design
sheets accordingly to reflect this and describe the culvert placement in more detail, per your comment.

b. Update the ledger to read “Parent tracts” as opposed to “Project Site Tracts” for consistency.
What is the difference between what is labeled as the Project Site Tracts vs the Site_Boundary?
Both attributes are pink.

Ledger and figure have been revised.

c. Was there an option to include the crossing above Trib 1A Lower as an internal crossing? Internal
crossing are typically preferred so they are protected and managed in perpetuity as part of the CE.

The landowner would prefer to have this area separate from the conservation easement, so it has not been
included as an internal crossing. Please note that that there are no proposed credits for Trib1A Upper,
which we have included to provide connectivity and protection of Trib1A Lower.

19. Figure 12-
a. Please include the culvert/crossing photo point locations on this figure.

Figure has been revised.

b. Please include and label existing wetlands on this figure.

Figure has been revised.

c. Please install a flow gauge on Trib 1B. Additionally, please ensure flow gauges are located in the
upper third of all reaches. To help supplement flow data it would be beneficial to also install game
cameras.

Comment noted for location of flow gauge, location in upper third and suggestion for game cameras. We
will revise the mitigation plan to reflect these additions.

20. Appendix F- Uniform Act document- FNI indicated that a notification was sent to the property owner
and a copy of the notification was located in the Appendix. Please include the document as indicated.

Document has been included in the mitigation plan.

21. Design Sheets-

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July 17, 2023
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a. C13 and C16- Were there culverts being installed for the road relocation above Trib 4 and 6? Please
include culvert type and dimensions in callout. Also, please callout all easement breaks (internal
and external) on the profile views. And please include a typical culvert crossing detail.

Yes, there are culverts being installed for the road relocation above Tribs 4 and 6 and we will add the
requested information to the callout. We will also callout easement breaks on the profile views and
provide a typical culvert crossing detail.

b. Noticed a design sheet for Wetland A, C, D was not included. Is this because work is limited in this
area to mainly only removing drain tiles?

Yes, that is correct. Because the work in the proposed wetlands is minimal, it is depicted on the larger
scale sheets.

22. General Comment: Since this project is adjacent to active agricultural lands, signage will be important
to help establish boundaries for the landowner. We recommend using horse-tape or some other visual
barrier for the first few years of monitoring. To confirm, does the easement boundary line on Trib 1A
Upper follow the centerline of the stream or does it follow the lines of the parent parcel? It will be
important to install signage more frequently along this area due to the sinuous easement line. If the CE
does not overlap the parent parcel, and if possible, recommend installing signage in a straighter line
somewhere between the parent parcel and CE to avoid potential future encroachments.

The easement boundary line on Trib1A Upper roughly follows the lines of the parent parcel, which is also
approximately the centerline of the stream. We will install signage more frequently per your
recommendation.

Please let us know if additional information is needed for the IRT’s further review. Feel free to call me at
[phone] with any questions.

Sincerely,

Ian Jewell
Associate/Project Manager
EXPAND EASEMENT TO
COVER WOODED WETLAND
AREAS UPSTREAM OF TRIBS
1B AND 1C
EXPAND EASEMENT
ADJACENT TO WETLAND
EXPAND EASEMENT
ADJACENT TO WETLAND
EXPAND EASEMENT
ADJACENT TO WETLAND