HomeMy WebLinkAboutTurkey - PRM Site - Response to Draft MP Comments_2024-02-02_Restoration Systems, LLC
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Response to Draft Mitigation Plan Comments Dated 11/22/2023
Turkey Mitigation Site
Yadkin River Basin – CU 03040201 – Anson County
USACE Action ID No. SAW-2023-00121
DWR Project No. 2023-1113 v1
Comments Received (Black Text) & Responses (Blue Text)
USACE Comments (Erin Davis):
1. Page 2, Section 1.0 – Note total LF & acres don’t equate total credit. The impact 2:1 LF and acre totals aren’t
double the impact totals.
Response: Language has been clarified in the mitigation plan. The mitigation plan is a permittee-responsible
plan and offset of impacts is on a linear feet basis. Permittee impacts have been doubled and mitigation
proposed for this project more than offsets the doubled impact amount. Tables 14 and 15A have been updated
to include a credit summary of stream and wetland mitigation provided to offset the impact amount for Vulcan’s
Individual Permit, SAW-2020-00807.
2. Page 6, Table 2 – Please confirm the number of marsh treatment areas. Are perched culverts being upgraded or
removed?
Response: The total number of marsh treatments is 8, with a quantity added to the plan sheets. Most culverts
are being removed and those perched will have reinforced rock as well to allow for aquatic passage.
3. Page 7, Section 5 – Please add an existing vegetative community characterization subsection and include a list
of invasive species observed onsite.
Response: Subsection 5.7.1 onsite invasive species and a vegetation identification table have been added to the
plan, providing information for the existing vegetative community on the site as well as identified invasive
species.
4. Page 9, Section 5.4 – Please include the NCLSS soil investigation report and detailed drained soil delineation
map(s).
Response: Given wetland re-establishment credit is not necessary to meet the mitigation needs of the Impact
Site, re-establishment credit has been removed from the Mitigation Plan. Wetland mitigation will be
accomplished through wetland rehabilitation and enhancement of existing wetlands delineated and approved
in the jurisdictional determination. A NCLSS was involved in the jurisdictional delineation of the site and soils
were reviewed as a part of the jurisdictional determination submittal. Areas of drained hydric soil will remain
on figures for informational purposes, as we expect these areas to become jurisdictional because of stream and
vegetation restoration activities. Wetland monitoring gauges have been moved into wetland rehabilitation
areas as requested in comment 26b.
5. Page 10, Section 5.5 – Was potential suitable habitat for the for Schwineitz Sunflower assessed within the
proposed project area? TCB coordination?
Response: Yes, please refer to the Biological Analysis (Appendix D), along with pg. 11 of the Mitigation Plan for
tree clearing seasons (May 15 – Aug 15). We are actively coordinating with USFWS on these species.
6. Page 13, Tables 4 & 5 – Please add a table footnote clarifying that Stream SA4 and Wetlands 13, 15 and 16 are
not located within the proposed PRM Site.
Response: Completed.
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7. Page 14, Section 5.8 – It would be helpful to have an NCSAM and NCWAM results summary table.
Response: Understood, and in future plans, a summary table will be provided. For purposes of this submittal,
please refer to Appendix B.
8. Page 16, Section 5.12.3 – Reach SA4 is not located within the proposed PRM site. Is basing proposed and existing
conditions model on an offsite stream suitable for the PRM site design? Was an existing conditions model run
on any of the small drainage intermittent reaches within the project site?
Response: Yes, an existing conditions and proposed model is appropriate for this site. The SA4 reach is
immediately adjacent to the PRM site and applicable in regard to drainage area size, flow regime, geometry,
and overall stream functions. Please see Appendix G for the existing and proposed 2D H&H models.
Additionally, stable cross-sections were surveyed in the SA1 and SA4 drainage and were used as supplemental
data to merge with publicly available and published regional curve data used to establish design criteria. Please
see Appendix F, which includes maps in the USGS Stream Stats report. Both reference reach locations were in
similar sized drainage areas. SA3 is included in the appendix; however, it was considered an outlier and not
incorporated into the final mini-regional curve to establish design criteria.
9. Page 19, Section 6.1.1 – Based on observations from other mitigation sites, soil compaction and low soil fertility
can be issues for vegetation establishment and vigor along Priority 2 cut benches and side slopes. Please place
a monitoring veg plot within a proposed P2 cut area.
Response: Noted. Please refer to Section 6.1.2. Topsoil will be removed prior to rough grading and reutilized
in appropriate areas during construction to reach final design elevations and to enhance survival of vegetation
establishment. Section 8.1 has been updated to state that each monitoring year at least one random vegetation
plot will be located within a Priority 2 cut area.
10. Page 21, Section 6.2.2 –
a. Reach SA4 is not located within the proposed PRM site, please remove references.
Response: Completed.
b. Design Drawing No. 38 does not show braided headwater restoration, please confirm that this approach is
being proposed for SA11. If so, please show on design drawings.
Response: SA11 will not have a braided system. SA11 starts at an existing culvert that will be replaced by
floodplain culverts, as noted. The new floodplain culverts are outside of the easement. Culverts were added to
the design plan view and the notes.
11. Page 23, Section 6.2.5 – Vernal pools, ephemeral pools, storage depressions and constructed depressions are
mentioned throughout the plan. Do these features differ in proposed location, design and/or function? If more
than 0.5-ft microtopographic grading is proposed, please include a design drawing feature callout and detail
(specifying max. depth). Grading of any depressions within a proposed wetland credit area should have a max.
depth of less than 1-ft, except potentially for wetland establishment areas. Grading of depressions outside of
wetland areas but within the floodplain should be designed to seasonally dry for habitat value.
Response: Noted. Vernal pools, etc. will not be excavated more than 0.5-ft. This section has been updated
specifying a max depth of 0.5-ft, refer to detail 3/D2 with note added to the plans.
12. Page 23, Section 6.2.8 – Based on past mitigation project reviews, typically marsh treatment features have a
max. depth of 2 feet or less. A BMP with a 4-ft pool depth would be considered more of a wet pond feature.
Please confirm the total number of marsh treatment areas proposed for this project (Table 2 and Figure 9).
Response: The total number of marsh treatment areas is 8 and has been updated in the narrative and on the
figures. Pool depths have been adjusted to 2-ft.
13. Page 24, Section 6.2.10 – Related to the livestock removal, please note the proposed decommissioning of the
existing well onsite shown on Drawing No. 9.
Response: A sentence was added to this section and a note was added to the design plan set.
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14. Page 25, Table 9 – The scientific name of brown top millet is Urochloa ramose.
Response: The scientific name was corrected in the table.
15. Page 27, Table 11 – If green ash is substituted in, the total percent stems should be capped at 5% due to the risk
of high mortality from the emerald ash borer. Also please limit box elder and eastern cottonwood stem totals
to 10% since both species are known to be prolific and could affect community diversity.
Response: Table 11 has been updated to include the planting limits for these species are noted in the table.
16. Page 28, Section 8.0 – Please provide an as-built redline drawing set identifying deviations and field changes
from the approved design drawings, including planting plan.
Response: Noted.
17. Page 31, Sections 8.3 – Please include discussion of the installation and monitoring of flow and bankfull
measurement gauges within this hydrology monitoring section.
Response: This section has been updated to include discussion of monitoring stream flow and bankfull events.
18. Page 31, Section 8.4 –
a. Please specify the bankfull performance standard of four events in separate years.
Response: Bankfull events will be monitored via evaluation of water levels in the stream with flow gauges. The
bankfull performance standard has been specified in Section 8.4 to clarify that the bankfull events must occur
in four separate years.
b. Based on the design drawings, upper SA10 is the only reach proposed as braided headwater. The SA10
stream length included in Table 14 appears to only account for the single thread reach segment. Therefore,
a braided headwater performance standard and monitoring protocol is not required. However, annual
visual monitoring should be performed to verify stability of flow paths and note potential problem areas
(e.g., headcuts). Also, please note that if a braided headwater stream was proposed it would be required
to meet 30 days consecutive flow annually and would not be considered an ephemeral feature.
Response: A photo monitoring station will be included to verify stability over the life of the project. A total of
20 feet downstream of the braided system will be creditable, being it is the restored tie-in to SA3.
19. Page 32, Section 8.5 –
a. What is the distance from the site to the Wadesboro data station? Is an onsite rain gauge proposed?
Response The Wadesboro weather station is ~5.5-miles from the site. An onsite rain gauge is proposed to be
installed downstream from the crossing located on SA1.
b. Please confirm that the growing season start and end dates will not change once established in the as-built
report.
Response: Growing season dates will not change.
c. Annual maintenance inspections of monitoring equipment and quarterly data downloads are encouraged.
Performance standard success cannot be inferred if required data is not provided.
Response: Understood.
d. Please note that wetland hydrology is an annual performance standard.
Response: Noted.
20. Page 33, Section 8.6 –
a. Please include previous years’ data in vegetation and stream summary tables.
Response: Noted.
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b. Visual Documentation – Please provide an annual visual assessment of the project area and easement
boundary, invasive species cover, encroachments, etc. Please include fixed photo stations at each cross
section, gauge location and easement break stream crossing. Please also include fix photos stations on all
restoration reaches that don’t have a cross section and/or gauge (e.g., SA6, SA10) and at the marsh
treatment area upstream of SA6.
Response: Annual assessment of boundaries, etc. will be included in the annual monitoring report. Photo points
have been added to Figure 9.
21. Page 34, Table 13 – Annual management of invasive species is strongly encouraged.
Response: Understood.
22. Page 36, Section 12 – Please remove the “UMBI” reference.
Response: Completed.
23. Page 37-38, Tables 14 & 15 – Please add a column indicating the proposed mitigation credit ratio.
Response: Completed.
24. Page 38, Table 15 – Please include breakdown of each proposed wetland area with associated acreage in this
table or an additional table.
Response: Added Table 15b to page 42 of the Mitigation Plan.
25. Figure 4 – The Existing Wetlands included in legend are not shown on map, please add.
Response: Figure 4 was updated to show the existing wetlands.
26. Figure 9 –
a. Flow gauges on all intermittent restoration reaches should be located within the upper one-third of the
reach, please shift gauges on the map accordingly. Please relocate the flow gauge from SA1 to SA5. Please
add gauges to measure bankfull events on lower SA1 and lower SA3.
Response: The gauge positions on the figure have been adjusted.
b. Please be cognizant of proposed microtopography grading when selecting groundwater gauge locations.
Depressions and fill areas should be avoided. Locations should be representative of the larger wetland
credit area. Please add a gauge to Wetland 2 and Wetland 5 rehabilitation areas.
Response: Given wetland re-establishment credit is not necessary to meet the mitigation needs of the Impact
Site, re-establishment credit has been removed from the Mitigation Plan. Wetland monitoring gauges have been
moved into wetland rehabilitation areas as requested.
c. All wetland credit areas associated with vegetative uplift (enhancement, rehab, reestablishment,
establishment) should be monitored using either fixed veg plots or random transects during the 7-year
monitoring period.
Response: Understood. A total of 12 vegetation plots have been established and a total of 12 random transects
will be used during the annual monitoring period for all wetland areas, which will be moved annually for
documentation. See Figure 9 for details.
d. The agency site meeting minutes figure showed marsh treatment areas upslope of SA2 and SA8. Why were
these BMP locations cut from this plan?
Response: Marsh treatment areas were added to the plans above SA2 and SA8.
27. Appendix A – Please indicate that Reach SA4 Photos 13 – 24 are not located within the proposed PRM site.
Response: The SA4 watershed is not part of this mitigation plan. The photos have been removed.
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28. Appendix F –
a. Reach SA4 was used to develop the site-specific regional curve. Similar question as the existing/proposed
conditions model, is SA4 representative of the small drainage area intermittent reaches located within the
PRM site proposed for restoration?
Response: Yes, even though SA4 is not part of the mitigation plan, it is representative of other smaller drainage
area streams in the mitigation plan and can be used when determining design criteria for the project.
b. Please confirm the SA1 drainage area. Table 7 notes a 314-acre drainage area for SA1.
Response: The drainage area has been confirmed for SA1 and is 314.48 acres.
c. Why do the drainage areas change for SA1 and SA4 between the site data and ecoregion data?
Response: Ecoregion data table has been revised.
d. The drainage areas for the seven intermittent streams onsite range from 2.1 ac. to 10.5 ac., which is
considerably smaller than the ecoregion reference streams listed. Are there any concerns designing site
streams based on larger drainage area systems?
Response: There are no concerns when using this data to determine design criteria. This data was supplemental
data used in combination with published ecoregion data.
e. Please provide a map showing reference stream locations relative to the PRM site.
Response: Stable reference cross-sections within the project areas were used in conjunction with published
ecoregion reference reach data (see comment 8 above). These locations were on SA1 and SA4. Locations of
these areas are located in Appendix F in the USGS Stream Stats report.
29. Appendix H – General design drawing questions/comments:
a. The project grading plans only show log grade control structures. Adding woody material to stream and
wetland systems is generally encouraged, particularly as habitat enhancement. However, the use of only
log grade control structures can be a concern for long-term channel stability, particularly for intermittent
B-type channels with slope. Based on observations from other mitigation sites, log structures can be more
prone to rot quicker and pipe along intermittent channels affecting the grade control functionality. Please
discuss the structure selection process, including the evaluation of risks.
Response: All log structures will have footer logs or rocks as additional measures for stability to reduce risks of
piping and structure failure. The majority of the logs will be submerged and within base flow levels; therefore,
accelerated rotting is not a concern. Logs used during installation have low decomposition rates and are not
anticipated to rot for several years, upon which vegetation and channel stability will be at an equilibrium to
where structures are not the primary means of grade control. On the downstream ends of the logs where the
thalweg will be present, additional bank stabilization measures in the form of boulders or wood will also be used
for additional bank protection. As necessary, rocks will be incorporated around culvert outlet areas along with
riffles to provide additional instream habitat and roughness.
b. Log step pools are called out along proposed C-type channels. Typically, C-type channels are associated with
a riffle-pool sequence rather than a step-pool sequence. The plan narrative discusses riffle-pool morphology
and increasing increase riffle length and natural pool-to-pool spacing (Table 1), as well as using constructed
riffles, alluvial riffles, and log riffles along restored streams. The design drawing legend include only a
habitat enhancement riffle structure. But no riffles are shown or called out on the plan drawings. If riffle
structures are proposed, please indicate type(s) and locations on plan view drawings and add design details
as needed. Also, please specify min./max. riffle length.
Response: The C-type channels are designed as riffle-pool sequences. Logs used in the C-type channels are
primarily used for grade control to establish and encourage the pool habitat between longer riffles. Habitat
enhancement riffles function the same as constructed and alluvial riffles but incorporate additional wood into
them for aquatic and instream habitat, as well as provide additional roughness. It is anticipated that riffles will
be created between all pools in the C-type channels. Upstream and downstream riffle stations and elevations
are shown on the stream profiles and plan views. The habitat enhancement riffle detail (1/D5) is to be applied
in each riffle. Riffle lengths for all Rosgen B channels will be between 0.5 to 3.0 feet of the bankfull width and
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Rosgen C channels will be between 1.3 and 4.0 feet to bankfull width. A constructed riffle detail (4/D5) was
added to the plan sheets.
c. There are no meander bend bank treatments proposed. Are there any concerns about long-term bank
stability?
Response: There are no concerns regarding long-term stability since geometry is designed to a stable dimension,
profile, and plan views based on reference data and published regional curve data. Nonetheless, if during
construction meanders appear to be tight and additional stabilization is warranted until vegetation is
established, a series of optional bank stabilization structures are provided on the design plan sheets. They
include root wads (3/D3), toe wood with reinforced earth and live brush layering (1/D4), and bank boulders
(3/D5).
d. Is sufficient bedform diversity and instream habitat enhancement uplift expected from installing only log
step/vane structures?
Response: Yes, habitat enhancement riffles having a combination of rock, logs, and snags are proposed
throughout the entire project, which will create bedform diversity and micropools throughout the project.
30. Drawing No. 2 – A Floodplain Sill is noted under Special Notes. If proposed for this project, please include a
design detail and show of plan drawings.
Response: Detail sheets have been revised to indicate location of Floodplain Sills within structures.
31. Drawing No. 4 – In the legend, please rename Stream Rehabilitation to Stream Restoration to be consistent with
the project narrative and figures.
Response: Completed.
32. Drawing No. 7 – Please confirm the callout “grade irregular topography +/- 0.5 ft. along proposed stream
floodplain” includes backfilling existing stream channels. Also, please add a max. depth to the callout (applies
to subsequent drawings).
Response: The grading contours and cross sections show the backfilling of existing stream channels. This note
is to alert the selected contractor to apply some irregularities in the final grade to be consistent with natural
ground and to provide additional floodplain roughness. We don’t feel comfortable putting a max depth on this
as the grading is a mean elevation. Irregular topography grading allows for the final grade to be 0.5 feet lower
or higher of that mean.
33. Drawing No. 8 – Backfilling of the existing channel is shown as wetland establishment in one area and
reestablishment in another, seemingly based on the adjacent wetland type. For consistency all channel backfill
areas proposed for wetland credit should be considered establishment due to the required hydric soil
development of the fill material. This comment applies to MMO1, MM03 and MM06.
Response: All wetland establishment and re-establishment areas have been removed from the plans. Wetland
rehabilitation and enhancement are the only located creditable resources.
34. Drawing No. 10 and 23 – Will livestock have access to the stream within the easement break upstream and/or
downstream of the bridge? If fencing is proposed, please include an overall fencing plan with approximate
locations of proposed gates.
Response: No livestock will enter the conservation easement area. The area will be fenced and is shown on the
plan.
35. Drawing No. 11 – Please confirm that all areas of existing channel located outside proposed limits of grading will
be backfilled (applies to subsequent drawings).
Response: Grading has been updated to show backfill in existing channels.
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36. Drawing No. 17 – The site meeting minutes indicate light EI approach at top of SA2, which would indicate a
current level of function and some areas of stability. However, limits of grading are shown along this entire
reach. Were there any stream, bank or wetland areas assessed to be stable and to be avoided/protected during
construction?
Response: There are no stable areas in the upstream reach of SA2. The limits of grading will, however, attempt
to be minimized to reduce overall disturbance of adjacent wetland area during implementation. SA2 shows
signs of incision and disconnection from the original floodplain as seen by several of the cross-sections shown
on Sheet 52 of the design plan sheets. Overall substrate and bedform is very limiting as seen in the profile of
the existing channel (Sheets 17-20 of design plan sheets) showing very limited if any shallow and deep pools.
Other sections of the channel are not as progressed with degradation and a more settle enhancement approach
is proposed.
37. Drawing No. 28 – In the site visit meeting minutes DWR recommended a braided headwater approached for the
upper SA5 reach. Are there any concerns about upper SA5 having enough flow to support a single stem stream
and maintain channel features through the surrounding wetland? With the amount of excavation proposed
please elaborate on the justification of a stream restoration approach through the existing Wetland 2.
Response: SA5 was designed as a Rosgen B channel due to its valley constrictions, and the slope was on average
3.5%, which is not conducive for a braided channel. According to the proposed 2D H&H model, both the 2-year
and 10-year models show sufficient flows to maintain hydrology in the adjacent wetland. The stream has been
designed to reconnect the floodplain to allow for additional surface flows to overtop the channel, further
providing hydrology inputs into the wetland complex.
38. Drawing No. 37 – Are there any concerns about creating flow paths within an existing wetland having a drainage
effect on the wetland? If the flow paths are shallower and more dispersed than the existing stream channel,
would wetland reestablishment or establishment be expected to develop downslope of the wetland
rehabilitation area?
Response: There are no concerns of losing drainage of an existing wetland with creating flow paths through it
since the floodplain will be reconnected to the resource and have direct hydrological connections from both
surface and groundwater sources. The current mitigation plan does not claim wetland re-establishment and
wetland establishment as being creditable resources.
39. Drawing No. 38 –
a. Is the existing culvert called out proposed be removed? If so, should limits of grading be extended
upstream? If not, please include culvert dimensions. Typically, structures proposed to remain are excluded
from the conservation easement or identified as internal crossings. If this structure is proposed to remain
within the easement, future maintenance allowances need to be discussed with the long-term steward and
included in the CE agreement.
Response: Yes, existing culvert will be removed and replaced in its current location with floodplain culverts.
The culverts will be located outside of the easement. Culverts and limits of grading have been updated on the
plan sheet.
b. Please provide context for the callout “armor sides of pool as necessary”. Does this callout apply to only
this specific location?
Response: Comment has been updated for SA6 and SA11 to state, “Add bank boulders to sides of pools” in
applicable areas below culvert outlets.
40. Sheet 60 –
a. The proposed borrow area located between SA7 and SA1 is not consistent with conditions required for
wetland reestablishment. If excavation is proposed in this area, the wetland type will need to be changed
to establishment due to the soil disturbance and consequent time required for hydric soil development.
Response: Final borrow areas will not affect or encroach upon wetland mitigation areas and will not be lower
than adjacent wetlands. Wetland establishment and reestablishment areas have been removed from the
mitigation plan as all wetland mitigation will be derived from wetland rehabilitation and enhancement of
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existing wetlands. Final grade of borrow areas adjacent to wetland mitigation assets will match existing grades
of wetland areas to avoid any potential drainage effect.
b. Three of the four proposed borrow areas are located in the vicinity of existing and/or proposed wetland
areas. Please discuss the potential risk of lateral drainage effect that excavating a borrow area adjacent to
wetland may pose. How could this affect the function uplift proposed in adjacent wetland rehabilitation
and enhancement areas?
Response: No drainage effect is anticipated since the borrow areas will be graded at the end of construction to
match existing grades or be graded at a higher elevation than the wetlands or streams.
41. Drawing No. D1 –
a. Marsh treatment area – The plan drawings show no swales or flow paths from any of the proposed marsh
treatment outlets, please confirm. If swales or flow paths are added during construction, please callout on
redline drawings.
Response: There is no plan to construct designated flow paths out of the treatment area. They will flow over a
large woody debris area to reduce shear stress and spread flows into the restored resources.
b. Braided flow path – Please specify a flow path max. depth.
Response: These marsh treatments are very flashy as they receive the initial stormwater runoff pulse and as a
result the max flow path depth is variable.
42. Drawing No. D2 – The bridge crossing example photo appears heavily armored, potentially more than necessary
to retain the appropriate channel dimension. Please consider aquatic passage limitations during construction of
these proposed crossings.
Response: Acknowledged and understood. The bridge armoring will be constructed to not restrict aquatic
passage and flow conveyance.
43. Drawing No. D3 –
a. Clay channel plug – A 5-ft minimum channel plug length is much shorter than what is typically proposed on
mitigation projects, which can be up to a 50-ft min. length in the coastal plain. Are there any concerns about
the stability or flow risks of installing a narrow plug?
Response: There are no concerns with the stability of the plugs if sufficient clay and impervious materials are
used. The plug, however, has been increased to a length of 10 feet on the details. Rootwads are optional, but
highly recommended, if sufficient materials for the plug are not used during construction. Plugs will be used
everywhere the existing channel crosses the proposed restoration alignment.
b. Rootwad – If proposed, please show this structure on plan drawings.
Response: Rootwads were added to the detail and shown as an optional feature depending on the location of
the plug. Typically, rootwads will be installed if the plug is on an outside meander of the proposed alignment.
44. Drawing No. D4 –
a. Toe wood and live brush layering – This is a commonly used bank structure on mitigation projects. As
designed it can add wood to the system, enhance pool habitat, and provide bank stabilization. Please show
proposed locations of this structure on plan drawings.
Response: This is only an option to be used. If used, it will be shown on the plan view in the as-built report.
b. Log step pool – Please consider aquatic passage in the design and construction of step pools throughout
the project. A footer rock is not typically called out on log step details for mitigation projects. Is there any
concern about shifting or piping between the log and rock? What are the proposed dimensions of footer
rocks?
Response: With sand bed streams, footers are recommended under log structures to reduce piping under the
structures. Structures will be installed to allow for aquatic passage with the upstream end of the log being
installed lower creating a thalweg and low flow channel. Structure dimension tables are included on the detail
sheets. Proposed dimension for footer rocks are a minimum diameter of 2-ft, described in the notes of bank
boulders detail (3/D5).
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45. Drawing No. D5 –
a. The bank boulders example photo shows what appears to be boulders lining a straight segment of stream.
For this project, how and where would bank boulders potentially be used (e.g., reinforce meander bends)?
A long section of rock lined channel is generally not consistent with mitigation project design objectives in
this ecoregion.
Response: Bank boulders would only be used along pool sides near culvert outlets for additional bank
stabilization during high flow events.
b. Section 6.0 (page 19) notes that field conditions may result in structure substitutions and the addition of
boulder riffles and boulder cross-vanes. Please provide typical design details for these structures and
identify them as potential substitution structures.
Response: These are optional structures, but not anticipated unless determined they are warranted during
construction and will be documented in the as-built report. Details (Rock Constructed Riffle 4/D5 and Boulder
Cross Vane 1/D6) have been added to the plan sheets.
46. Drawing No. D6 –
a. Cascade – Please identify the max. pool depth.
Response: This detail has been removed.
b. Wetland cell – Where is this feature being proposed? Will these areas be seeded and planted with bareroot
stems?
Response: Wetland grading may be required in wetland rehabilitation areas where this detail shall be followed.
These areas will be seeded with a permanent wetland seed mix and planted with bareroot stems from the
piedmont/low mountain alluvial forest planting assemblage.
47. General Mitigation Plan Comment – Summary tables are an efficient tool to aid in agency plan review. Please
consider adding a project attribute table, essential morphology parameters table, and monitoring summary
table (see examples).
Response: Understood and will provide more tables for the next project.
48. The total endowment specified by BWI for $56,826 in Appendix J doesn’t match the total included by Davey/RS
in Section 11 for $50,529. It appears that the $50,529 is a carryover by Davey/RS from Hood Swamp mitigation
plan narrative, which should be reviewed and updated as needed.
Response: Our apologies on the oversight, the document was updated to reflect the correct endowment
amount detailed in Appendix J.
USACE Comments (Todd Tugwell):
1. I have not looked at the calculations for how the endowment amount was determined, but recommend that
RS/Davey lay out in some detail how they reached the requested endowment amount, including some basic line
items for annual or other expenses, capitalization rate, etc. In general, the bottom line is that if BWI is confident
that they can steward the site and it meets our expectations, that would address our main concerns.
Response: RS worked with BWI, and BWI has provided an updated commitment letter dated 1/30/2024.
DWR Comments (Maria Polizzi):
1. Can stream crossings be internal to the easement? Especially if these crossings are solely for agricultural access,
language could be added to the conservation easement agreement that would allow landowner access in these
locations. This would allow the long-term steward to handle all maintenance responsibilities.
Response: We understand and appreciate DWR’s (and the USACE’s) preference for internal crossings associated
with agricultural access. Conversations were had with the landowner, including us providing example language
used on previous mitigation sites for maintenance of internal crossings. However, the landowner did not want
to internalize the crossings. We will continue to pursue this option on future sites.
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2. Page 19, Section 6.1.1: The plan states that no soil compaction or fertility issues will result from the PRM
construction activities. Please provide more detail discussing how soil structure and fertility will be preserved.
Will low tire pressure equipment be used? What about haul roads or other high traffic areas?
Response: Section 6.1.1 has been updated to include discussion related to preservation of soil structure and
fertility. The section includes treatment approaches if soil structure and/or fertility issues are observed during
construction.
3. Page 22, Section 6.2.3: How will the stream bed elevation be raised? The plan states that it will be similar to the
Priority 1 approach, but Priority 1 is typically offline and constructs a new channel, rather than in-line for E1.
More information about the type of fill, construction strategy and stabilization plan would be helpful.
Response: Stream Enhancement Level I (EI) is only applied in SA2 for 309-linear feet. Fill material will be used
from excavating new channel in other areas nearby, re-used, and compacted in approximate 1-ft lifts to raise
the streambed elevation. The stream is currently incised with a head-cut and needs restored to historic
elevations. Overall dimension and profile will be restored, while channel pattern remains.
4. Pages 20-24, Section 6: Is the approach the same for all EII reaches, E1 reaches, etc? Generally, the mitigation
approach section is broken down by individual reach, rather than strategy type. Because different reaches often
require slightly different approaches (full buffer planting vs. minimal or supplemental planting, etc.), it is helpful
to have this more granular breakdown. If the approaches are exactly the same, this may not be necessary.
Response: Stream enhancement is only proposed on SA2 with two different levels proposed due to existing
conditions of impairment. Stream Enhancement Level I (EI) includes the headwaters of SA2 extending 309-linear
feet. Currently, there is a head-cut and the stream has incised, disconnecting itself from the historic floodplain.
The EI approach involves restoration of dimension and profile to raise the stream bed elevation and reconnect
the channel to its original floodplain. Overall pattern for this section of stream is stable and will be maintained.
Additional riparian buffer and supplemental plantings will then be installed. The downstream section of SA2
implements a stream enhancement Level II (EII) approach and extends 506-linear feet. This section of channel
has a stable dimension, pattern, and profile, therefore, only a riparian buffer and supplemental plantings will be
installed. The channels will also be excluded from livestock access.
5. Page 23, Section 6.2.8: The outlets of the marsh sills are described as “similar to a level spreader”. DWR is
concerned that this structure type may have issues long term. Level spreader structures often suffer from
preferential flow paths forming, causing piping. These have been a popular structure type in erosion control and
stormwater, however consistent monitoring and maintenance is anticipated in these instances. In recent years
they have also become less popular due to the frequency of failure and constant repair needs. Is there another
outlet structure that could be used that would have better long term stability without maintenance?
Response: The terminology of level spreader has been removed from the mitigation plan. The purpose of log
and large woody debris near the outlet of the marsh treatment is to create roughness to slow down water
exiting from the treatment area. The wood outlet will be compacted and dense to reduce preferential flow
paths and piping. The area will also be concentrated to direct flows from the marsh treatment area directly into
the restored channel down valley. This structure type has been implemented on other projects we have
designed and constructed and proven to be stable and effective, that said we will visually monitor these
structures to provide maintenance if required.
6. Page 24, Section 6.2.9: If the main culvert for each crossing will be constructed to pass the 10-year storm event,
what storm event will the incorporated floodplain culverts raise the overall crossing to?
Response: The floodplain culverts are in place to alleviate stress to the main culvert during out of bank events.
They are not designed for a specific storm event but serve as an additional measure to maintain stability of the
main culvert during these out of bank events. The bridge crossings will be installed high enough to allow for the
100-YR storm event to pass under it.
Page 11 of 13
7. Page 25, Permanent Seed Mix (Table 10):
a. Please note that some Lespedeza species are invasive. I am not familiar with this specific Lespedeza
(Lespedeza capitata), so please confirm that this variety is not invasive or remove it from the planting list.
Response: Lespedeza capitata is native to NC and offers the following benefits: is a high-value wildlife plant,
is adaptable to different soil types, is drought tolerant, and adds nitrogen to the soil.
https://plants.ces.ncsu.edu/plants/lespedeza-
capitata/#:~:text=Round%2Dheaded%20bush%20clover%20is,all%20areas%20of%20North%20Carolina
b. Elymus virginicus and Carex vulpinoidea are listed twice with different percentages for each listing.
Response: Those species were listed twice as we intended to present two permanent seeding tables. Table
10 has been updated to include 2 tables (10A Permanent Seed Mix – Sitewide for native Diversity, Pollinator
Benefits, & Stabilization and 10B Permanent Seed Mix – Marsh Treatments, Streamside, & Wetlands).
c. The total percentage of species planted greatly exceeds 100%. Please clarify how to interpret this table, if I
am misunderstanding, or update to reflect accurate percentages.
Response: Part of this was the two permanent seeding table were merged into one, which has been
updated. Table 10A percentages have been updated based on the removal of Cosmos bipinnatus and
Consolida ajacis and those percentages were allocated to other species. Table 10A and 10B both equal
100%.
d. Cosmos bipinnatus and Consolida ajacis are not native.
Response: Understood these species have been removed.
e. DWR appreciates the species diversity provided by this planting list.
Response: Thank you.
8. Page 30, Section 8.2: Please include a note that volunteer plants cannot be counted towards success criteria
until they have been present for at least two growing seasons.
Response: Mitigation plan has been updated.
9. Page 32, Section 8.5: A hydroperiod of 10% is proposed based on the Worsham soil series. Why is the Worsham
soil series selected as the representative series? Worsham is not listed at all on the NRCS soil survey map, and
no LSS soil survey report is included. A LSS report may be able to provide best professional judgement as to why
the NRCS soil survey may not accurately reflect site conditions and propose an alternative soil series that better
reflects this site.
Response: The soils were mapped by a NCLSS during the jurisdictional delineation of the project, however a soil
survey report was not generated. The mitigation plan has been updated to provide wetland mitigation through
wetland rehabilitation and enhancement of existing jurisdictional wetlands identified in the approved
jurisdictional determination. Hydrology is one of the functional uplifts that will be provided as a result of the
stream restoration activities. Worsham was selected as the representative soil series as it is within the Ultisol
soil order which is the soil order associated with the surrounding upland soils. Also, the Worsham soil series is
primarily located at the heads of drains which matches the landscape position of the wetlands observed at the
Project.
10. Page 33, Section 8.6: The conservation easement boundary should be walked and inspected regularly
(preferably every quarter), and highlights should be included in the annual report. If encroachments are
identified the report should include steps that have been (or will be) taken to resolve the issue.
Response: Noted. Section 8.6 has been updated to include Visual Reporting as a part of monitoring.
11. DWR seconds the USACE comments 1 and 23. Until mitigation credit ratios are proposed and agreed upon, the
total mitigation credit generated by the project cannot be determined.
Response: Tables 14 and 15A have been updated to include a mitigation ratio and credit summary of stream
and wetland mitigation provided to offset the impact amount for Vulcan’s Individual Permit, SAW-2020-00807
Page 12 of 13
12. Figure 8: Will the entire site be planted? Based on Figure 8 it appears so, but since a portion of the project is
currently forested, it was unclear whether these areas would be removed during construction and replanted, or
if any were able to remain. Please clarify.
Response: The entire site will be planted due to invasive species management that will be employed across the
site prior to restoration. Desirable species in areas that are currently forested will be preserved to the greatest
extent possible.
13. Figure 9: DWR requests an additional cross-section on the E1 section of SA2.
Response: An additional cross-section has been added to Figure 9.
14. Appendix G Drawings 1: Thank you for including these figures, they are very helpful visualizations.
Response: No problem.
15. Conservation Easement Overview Figure (Appendix): The arrows showing easement widths are very helpful, and
DWR appreciates the wider buffers to help reduce agricultural inputs.
Response: No problem.
Plan Sheets:
16. Design Plans Drawing 37:
a. Typically structures like a log step pool are not included in headwater valley restoration. The goal for these
channels is that stream movement can occur laterally over time, creating new braids, etc. By building a
structure, the channel becomes locked in place and this function is not able to occur as intended.
Response: This structure has been removed.
b. It appears that there is one wider, central channel in the braided headwater section. Is there a reason for
this? Would it be better to have all braids be a similar size?
Response: The plans have been updated and all braided channels are similar in size.
17. Drawing D1, Substrate Restoration Detail: The specification describes that course alluvium from the current
channel should be the preferred material for substrate restoration. However, the definition of course alluvium
includes material sized between 0.08 inches and 80 inches, which is a huge range. DWR does not feel that 80
inches would be appropriate for substrate replacement at this site. Please propose a more limited size range for
course alluvium that would be realistic for this project.
Response: The generalized substrate detail information has been removed and additional substrate information
was incorporated into the habitat enhancement riffle detail on Sheet D5. On-site alluvium shall be the preferred
substrate incorporated into riffles, however, if supplemental materials are needed, Class A (2-6”) would be used.
18. Drawing D2, Bridge Crossing: Remove general note 2. The crossing should be constructed in a dewatered
condition, and therefore alternatives to dry construction are not needed. DWR also agrees with the USACE
comment 42 and recommends minimizing stone application to only what is necessary to provide stability.
Response: Noted, consideration during construction per this recommendation will occur.
19. Drawing D5, Habitat Enhancement Riffle:
a. It appears that boulders line the channel on these riffle sections, which does not seem necessary from a
stability standpoint. DWR would encourage an alternative design that uses live stakes or other more natural
bank stabilization strategy.
Response: Detail has been updated to include erosion control matting and livestakes to stabilize banks.
b. Why is this specification is marked as “optional”? Consider adding specified locations to the plan where this
structure will be installed.
Response: Locations for habitat riffles will be determined during construction and locations will be included
as redlines on as-built drawings.
Page 13 of 13
20. Drawing D6, Cascade Riffle: Typically cascades are found in mountain streams where slopes are very steep. Is
there a reason why cascade riffles were selected for this project?
Response: Detail has been removed.
21. Drawing D6, Log/Rock Step Pool: Similar to the USACE comment 44b regarding Drawing D4, footer rocks are
typically not used with log structures and could lead to piping issues. Please provide additional justification for
this design or consider using footer logs for log-based structures.
Response: All log structures will have footer logs or rocks as additional measures for stability to reduce risks of
piping and structure failure. The majority of the logs will be submerged and within base flow levels; therefore,
rotting is not a concern. Logs used during installation have low decomposition rates and are not anticipated to
rot for several years, upon which vegetation and channel stability will be at an equilibrium to where structures
are not the primary means of grade control. On the downstream ends of the logs where the thalweg will be
present, additional bank stabilization measures in the form of boulders or wood will also be used for additional
bank protection. As necessary, rocks will be incorporated around culvert outlet areas along with riffles to
provide additional instream habitat and roughness.
22. Design Drawings Overall:
a. Thank you for including the photo examples of each specification. These are helpful.
Response: No problem.
b. DWR would appreciate if (at least) the design plans could be provided in hard copy in the future. DWR had
some difficulty viewing the engineering drawings due to their large size and complexity.
Response: Noted.